Automated Three-Dimensional Measurement of Glenoid Version and Inclination in Arthritic Shoulders

A gender and size specific evaluation of Grammont-type inlay versus lateralizing onlay stem designs in achieving lateralization and distalization in reverse shoulder arthroplasty

INTRODUCTION

In reverse shoulder arthroplasty (RSA) new designs enable greater amounts of lateralization to prevent instability and scapular notching and increase range of motion, however, excessive lateralization leads to stress upon the acromion that can result in scapular spine fatigue fractures. Aim of this study was to gender- and size-specifically assess the influence of glenosphere size and different humeral designs on lateralization, distalization, and bony impingement-free range of motion (ROM) in patients undergoing RSA.

METHODS

Computed tomography scans from 30 osteoarthritic patients (f:15, m:15) and 20 cuff tear arthropathy patients (f:10, m:10) were used to virtually simulate RSA implantation. The efficacy of an inlay Grammont-type system vs. an onlay lateralizing system combined with different glenosphere sizes (36 mm vs. 42 mm) in achieving ROM, lateralization, and distalization was evaluated. Moreover, gender and patient's constitution were correlated to humeral size by radiologically measuring the best-fit circle of the humeral head.

RESULTS

A different amount of relative lateralization was achieved in both genders using large glenospheres and onlay designs. Latter yielded a higher ROM in all planes for men and women with a 42 mm glenosphere; with the 36 mm glenosphere, an increased ROM was observed only in men. The 155° inlay design led to joint medialization only in men, whereas all designs led to lateralization in women. When adjusting the absolute amount of lateralization to humerus' size (or patient's height), regardless of implant type, women received greater relative lateralization using 36 mm glenosphere (inlay: 1%; onlay 12%) than men with 42 mm glenosphere (inlay: -3%; onlay: 8%).

CONCLUSION

The relative lateralization achieved using onlay design is much higher in women than men. Small glenospheres yield greater relative lateralization in women compared to large glenospheres in men. Humeral lateralization using onlay designs should be used cautiously in women, as they lead to great relative lateralization increasing stress onto the acromion.

LEVEL OF EVIDENCE

Basic Science Study, Computer Modeling.

Three-dimensional analysis of biplanar glenoid deformities: what are they and can they be virtually reconstructed with anatomic total shoulder arthroplasty implants?

BACKGROUND

Descriptions of glenoid deformities in glenohumeral osteoarthritis (GHOA) have focused on the axial plane. Less is known regarding arthritic glenoids with higher amounts of superior inclination and little evidence exists to guide management of inclination or combined version-inclination deformity when performing anatomic total shoulder arthroplasty (aTSA). We hypothesized that biplanar deformities (BD) would be present in a higher proportion of GHOA patients than previously appreciated, and these deformities would be difficult to adequately reconstruct with contemporary aTSA implants.

METHODS

A retrospective query was performed of GHOA patients indicated for TSA 2012-2017 with a computed tomography (CT) scan within three months of surgery. Images were uploaded to three-dimensional (3D) software for automated measurements. Glenoids with superior inclination ≥10°, and retroversion ≥20° were considered to have BD. Walch classification was determined, and C-type glenoids were excluded. Rotator-cuff muscle cross-sectional area (CSA) was measured and fatty infiltration was graded. Glenoids with BD were virtually planned for aTSA with correction to neutral inclination and version, then with 5° superior inclination and 10° retroversion.

RESULTS

Two-hundred and sixty-eight shoulders in 250 patients were included; average age was 65 years, 67% male. There were no differences in inclination between Walch types (P = .25). Twenty-nine shoulders with BD were identified (11%). These deformities were not associated with age (P = .47) or gender (P = .50) but were skewed towards Walch B-type, specifically B2 (P = .03). Acromial index and posterior humeral head subluxation were higher in BD patients (P = .04, P < .001, respectively). Biplanar deformities had similar cuff CSA compared to those without but were less frequently associated with fatty infiltration of the subscapularis (P = .05). When correcting to neutral version and inclination, 41% BD could not be reconstructed. Of those that could, 94% required augmented implants. When correcting to 5° superior inclination and 10° retroversion, 10% could not be reconstructed. Of those that could, 58% required augmented implants. With partial correction, augment use was predicted by retroversion >26° (P = .009). Inclination did not predict augment use (P = .90). Final implant position commonly involved unseating in the posterosuperior quadrant and cancellous exposure in the anteroinferior quadrant.

CONCLUSIONS

This retrospective computed tomography (CT)-based study of 268 shoulders with GHOA found an 11% prevalence of BD. These deformities were commonly associated with Walch B2 wear patterns. Virtual aTSA planning showed a high failure rate (41%) when correcting to neutral version and inclination. Posteriorly augmented implants were frequently required, and often still involved unseating in the posterosuperior quadrant, increased cancellous exposure in the anteroinferior quadrant, and vault perforation.

Optimizing stability and motion in reverse shoulder arthroplasty with a 135° neck-shaft-angle: a computer model study of standard versus retentive humeral inserts

Background

There has been a trend to shift from a 155° and 145° neck-shaft-angle (NSA) to a more "anatomical" reverse shoulder arthroplasty with less distalization and a 135° NSA. Multiple studies have shown that a 135° NSA is beneficial for motion. There are some concerns about primary implant stability with a 135° NSA. When instability is detected, increasing the tension with thicker inlays or changing the NSA to 145° are possible solutions. A retentive 135° (Ret135) inlay may be an alternative to avoiding increased distalization; however, retentive liners are widely regarded as salvage options reducing range of motion (ROM) and avoided by most surgeons. The hypothesis of this study was that a retentive 135° insert of the tested implant system may not have drawbacks for impingement-free ROM compared to a standard 145° insert (Sta145).

Methods

In this computer model study, 22 computed tomographic scans (11 males/11 females) were used to create models with a constant humeral stem (Perform/Stryker) and +3 mm lateralized baseplate +36 mm glenosphere for females and +6 mm lateralized baseplate +39 mm glenosphere for males using Blueprint software (Imascap, Brest, France). A Ret135, standard 135° (Sta135), and Sta145 (+10°) insert were compared for adduction (ADD), extension (EXT), external rotation (ER), and internal rotation (IR) all with the arm at the side as well as for combined IR (CIR = EXT + IR) and combined notching relevant (CNR) ROM (EXT + ER + IR + ADD).

Results

Sta135 showed significantly better ROM for ER, IR, ADD, EXT, CNR ROM, and CIR compared to Ret135 (P < .05) and significantly better EXT and ADD compared to Sta145 (P < .0001). Comparison of Ret135 and Sta145 showed equivalent ROM performance, which was slightly better but nonsignificant for ADD (P = .16), EXT (P = .31), CNR ROM (P = .7), and CIR (P = .54) in favor of Ret135. Isolated IR (P = .39) and ER (P = .32) were slightly better but nonsignificant in favor of a Sta145.

Conclusion

For this implant system tested in a computer model, a 135° standard liner offers the best ROM. A 135° retentive liner maintains at least equivalent CIR and motion to prevent notching compared to a standard 145° liner. 135° retentive liners are more than salvage options and may help to prevent distalization and overtensioning by increased liner thickness.

Automatic quantification of scapular and glenoid morphology from CT scans using deep learning

OBJECTIVES

To develop and validate an open-source deep learning model for automatically quantifying scapular and glenoid morphology using CT images of normal subjects and patients with glenohumeral osteoarthritis.

MATERIALS AND METHODS

First, we used deep learning to segment the scapula from CT images and then to identify the location of 13 landmarks on the scapula, 9 of them to establish a coordinate system unaffected by osteoarthritis-related changes, and the remaining 4 landmarks on the glenoid cavity to determine the glenoid size and orientation in this scapular coordinate system. The glenoid version, glenoid inclination, critical shoulder angle, glenopolar angle, glenoid height, and glenoid width were subsequently measured in this coordinate system. A 5-fold cross-validation was performed to evaluate the performance of this approach on 60 normal/non-osteoarthritic and 56 pathological/osteoarthritic scapulae.

RESULTS

The Dice similarity coefficient between manual and automatic scapular segmentations exceeded 0.97 in both normal and pathological cases. The average error in automatic scapular and glenoid landmark positioning ranged between 1 and 2.5 mm and was comparable between the automatic method and human raters. The automatic method provided acceptable estimates of glenoid version (R2 = 0.95), glenoid inclination (R2 = 0.93), critical shoulder angle (R2 = 0.95), glenopolar angle (R2 = 0.90), glenoid height (R2 = 0.88) and width (R2 = 0.94). However, a significant difference was found for glenoid inclination between manual and automatic measurements (p < 0.001).

CONCLUSIONS

This open-source deep learning model enables the automatic quantification of scapular and glenoid morphology from CT scans of patients with glenohumeral osteoarthritis, with sufficient accuracy for clinical use.

Is preoperative 3D planning reliable for predicting postoperative clinical differences in range of motion between two stem designs in reverse shoulder arthroplasty

BACKGROUND

We aim to predict a clinical difference in the postoperative range of motion (RoM) between 2 reverse shoulder arthroplasty (RSA) stem designs (Inlay-155° and Onlay-145°) using preoperative planning software. We hypothesized that preoperative 3D planning could anticipate the differences in postoperative clinical RoM between 2 humeral stem designs and by keeping the same glenoid implant.

METHODS

Thirty-seven patients (14 men and 23 women, 76 ± 7 years) underwent a BIO-RSA (bony increased offset-RSA) with the use of preoperative planning and an intraoperative 3-dimensional-printed patient-specific guide for glenoid component implantation between January 2014 and September 2019 with a minimum follow-up of 2 years. Two types of humeral implants were used: Inlay with a 155° inclination (Inlay-155°) and Onlay with a 145°inclination (Onlay-145°). Glenoid implants remained unchanged. The postoperative RSA angle (inclination of the area in which the glenoid component of the RSA is implanted) and the lateralization shoulder angle were measured to confirm the good positioning of the glenoid implant and the global lateralization on postoperative X-rays. A correlation between simulated and clinical RoM was studied. Simulated and last follow-up active forward flexion (AFE), abduction, and external rotation (ER) were compared between the 2 types of implants.

RESULTS

No significant difference in RSA and lateralization shoulder angle was found between planned and postoperative radiological implants' position. Clinical RoM at the last follow-up was always significantly different from simulated preoperative RoM. A low-to-moderate but significant correlation existed for AFE, abduction, and ER (r = 0.45, r = 0.47, and r = 0.57, respectively; P < .01). AFE and abduction were systematically underestimated (126° ± 16° and 95° ± 13° simulated vs. 150° ± 24° and 114° ± 13° postoperatively; P < .001), whereas ER was systematically overestimated (50° ± 19° simulated vs. 36° ± 19° postoperatively; P < .001). Simulated abduction and ER highlighted a significant difference between Inlay-155° and Onlay-145° (12° ± 2°, P = .01, and 23° ± 3°, P < .001), and this was also retrieved clinically at the last follow-up (23° ± 2°, P = .02, and 22° ± 2°, P < .001).

CONCLUSIONS

This study is the first to evaluate the clinical relevance of predicted RoM for RSA preoperative planning. Motion that involves the scapulothoracic joint (AFE and abduction) is underestimated, while ER is overestimated. However, preoperative planning provides clinically relevant RoM prediction with a significant correlation between both and brings reliable data when comparing 2 different types of humeral implants (Inlay-155° and Onlay-145°) for abduction and ER. Thus, RoM simulation is a valuable tool to optimize implant selection and choose RSA implants to reach the optimal RoM.

Comparison of Manual Two-dimensional and Automated Three-dimensional Methods of Assessing Shoulder Joint Morphology through Computed Tomography Images

Objective  To evaluate the interobserver agreement in the measurement of anatomical parameters of the shoulder using manual methods of two-dimensional (2D) computed tomography (CT) unformatted in the plane of the scapula and to compare them with the automated measurement obtained through the Blueprint (Wright Medical, Memphis, TN, United States) software, which uses reconstructed three-dimensional (3D) images. Methods  The present is a cross-sectional study in which 2D CT images of 38 patients with different diagnoses were used. The anatomical parameters were measured by the manual methods described by Friedman et al., the glenoid vault method, the Maurer et al. method, and shoulder subluxation according to Walch et al., by five independent qualified surgeons and compared with the parameters obtained through the Blueprint automated software. Results  Significant differences were found between the manual measurement version obtained through the Friedman et al. method and the automated version. The mean values found for inclination did not show statistically significant differences among the methods. The mean value found for subluxation showed significant differences between the average observed in the analyses performed by the automated method and those performed by the surgeons. Conclusion  The manual measurements of glenoid version and inclination performed by experienced surgeons are effective, and the vault method is superior to the Friedman et al. method in the analysis of severe glenoid deformities.

Can we screen opportunistically for low bone mineral density using CT scans of the shoulder and artificial intelligence?

OBJECTIVE

To evaluate whether the CT attenuation of bones seen on shoulder CT scans could be used to predict low bone mineral density (BMD) (osteopenia/osteoporosis), and to compare the performance of two machine learning models to predict low BMD.

METHODS

In this study, we evaluated 194 patients aged 50 years or greater (69.2 ± 9.1 years; 170 females) who underwent unenhanced shoulder CT scans and dual-energy X-ray absorptiometry within 1 year of each other between January 1, 2010, and December 31, 2021. The CT attenuation of the humerus, glenoid, coracoid, acromion, clavicle, first, second, and third ribs was obtained using 3D-Slicer. Support vector machines (SVMs) and k-nearest neighbours (kNN) were used to predict low BMD. DeLong test was used to compare the areas under the curve (AUCs).

RESULTS

A CT attenuation of 195.4 Hounsfield Units of the clavicle had a sensitivity of 0.577, specificity of 0.781, and AUC of 0.701 to predict low BMD. In the test dataset, the SVM had sensitivity of 0.686, specificity of 1.00, and AUC of 0.857, while the kNN model had sensitivity of 0.966, specificity of 0.200, and AUC of 0.583. The SVM was superior to the CT attenuation of the clavicle (P = .003) but not better than the kNN model (P = .098).

CONCLUSION

The CT attenuation of the clavicle was best for predicting low BMD; however, a multivariable SVM was superior for predicting low BMD.

ADVANCES IN KNOWLEDGE

SVM utilizing the CT attenuations at many sites was best for predicting low BMD.

Are glenoid retroversion, humeral subluxation, and Walch classification associated with a muscle imbalance?

BACKGROUND

The etiology of humeral posterior subluxation remains unknown, and it has been hypothesized that horizontal muscle imbalance could cause this condition. The objective of this study was to compare the ratio of anterior-to-posterior rotator cuff and deltoid muscle volume as a function of humeral subluxation and glenoid morphology when analyzed as a continuous variable in arthritic shoulders.

METHODS

In total, 333 computed tomography scans of shoulders (273 arthritic shoulders and 60 healthy controls) were included in this study and were segmented automatically. For each muscle, the volume of muscle fibers without intramuscular fat was measured. The ratio between the volume of the subscapularis and the volume of the infraspinatus plus teres minor (AP ratio) and the ratio between the anterior and posterior deltoids (APdeltoid) were calculated. Statistical analyses were performed to determine whether a correlation could be found between these ratios and glenoid version, humeral subluxation, and/or glenoid type per the Walch classification.

RESULTS

Within the arthritic cohort, no statistically significant difference in the AP ratio was found between type A glenoids (1.09 ± 0.22) and type B glenoids (1.03 ± 0.16, P = .09), type D glenoids (1.12 ± 0.27, P = .77), or type C glenoids (1.10 ± 0.19, P > .999). No correlation was found between the AP ratio and glenoid version (ρ = -0.0360, P = .55) or humeral subluxation (ρ = 0.076, P = .21). The APdeltoid ratio of type A glenoids (0.48 ± 0.15) was significantly greater than that of type B glenoids (0.35 ± 0.16, P < .01) and type C glenoids (0.21 ± 0.10, P < .01) but was not significantly different from that of type D glenoids (0.64 ± 0.34, P > .999). When evaluating both healthy control and arthritic shoulders, moderate correlations were found between the APdeltoid ratio and both glenoid version (ρ = 0.55, P < .01) and humeral subluxation (ρ = -0.61, P < .01).

CONCLUSION

This in vitro study supports the use of software for fully automated 3-dimensional reconstruction of the 4 rotator cuff muscles and the deltoid. Compared with previous 2-dimensional computed tomography scan studies, our study did not find any correlation between the anteroposterior muscle volume ratio and glenoid parameters in arthritic shoulders. However, once deformity occurred, the observed APdeltoid ratio was lower with type B and C glenoids. These findings suggest that rotator cuff muscle imbalance may not be the precipitating etiology for the posterior humeral subluxation and secondary posterior glenoid erosion characteristic of Walch type B glenoids.

Rate of incidental findings on routine preoperative computed tomography for shoulder arthroplasty

BACKGROUND

Incidental findings are commonly noted in advanced imaging studies. Few data exist regarding the rate of incidental findings on computed tomography (CT) for preoperative shoulder arthroplasty planning. This study aims to identify the incidence of these findings and the rate at which they warrant further work-up to help guide orthopedic surgeons in counseling patients.

METHODS

A retrospective review was performed to identify patients with available preoperative shoulder CT who subsequently underwent shoulder arthroplasty procedures at a single institution between 2015 and 2021. Data including age, sex, and smoking status were obtained. Radiology reports for CTs were reviewed for incidental findings and categorized based on location, tissue type, and/or body system. The rate of incidental findings and the rate at which further follow-up was recommended by the radiologist were determined.

RESULTS

A total of 617 patients was identified. There were 173 incidental findings noted in 146 of these patients (23.7%). Findings ranged from pulmonary (59%), skin/soft tissue (16%), thyroid (13%), vascular (9%), spinal (2%), and abdominal (1%) areas. Of the pulmonary findings, 50% were pulmonary nodules and 47% were granulomatous disease. Overall, the final radiology report recommended further follow-up for 50% of the patients with incidental findings.

CONCLUSIONS

Incidental findings are relatively common in preoperative CTs obtained for shoulder arthroplasty, occurring in nearly one-quarter of patients. Most of these findings are pulmonary in nature. Overall, half of the patients with incidental findings were recommended for further follow-up. These results establish population data to guide orthopedic surgeons in patient counseling. Level of evidence: III.

The Kouvalchouk procedure vs. distal tibial allograft for treatment of posterior shoulder instability: the deltoid "hammock" effect exists

BACKGROUND

In 1993, Kouvalchouk described an acromial bone block with a pedicled deltoid flap for the treatment of posterior shoulder instability. This procedure provides a "double blocking" effect in that the acromial autograft restores posterior glenoid bone loss and the deltoid flap functions as a muscular "hammock" resembling the sling effect of the conjoint in the Latarjet procedure. The primary aim of this study was to compare the Kouvalchouk procedure to distal tibial allograft (DTA) reconstruction for the management of posterior shoulder instability with associated bone loss, while the secondary aim was to evaluate the deltoid hammock effect.

METHODS

Ten upper extremity cadavers were evaluated using a validated shoulder testing apparatus in 0° and 60° of glenohumeral abduction in the scapular plane. Testing was first performed on the normal shoulder state and was followed by the creation of a 20% posterior glenoid defect. Subsequently, the Kouvalchouk and DTA procedures were conducted. Forces of 0N, 5N, 10N, and 15N were applied to the posterior deltoid tendinous insertion on the Kouvalchouk graft along the physiological muscle line-of-action to evaluate the 'hammock" effect of this procedure. Testing was additionally performed on the Kouvalchouk bone graft with the deltoid muscle sectioned from its bony attachment. For all test states, a posteriorly directed force was applied to the humeral head perpendicular to the direction of the glenoid bone defect, with the associated translation quantified using an optical tracking system. The outcome variable was posterior translation of the humeral head at an applied force magnitude of 30N.

RESULTS

The Kouvalchouk procedure with the loaded deltoid flap (10N: P = .039 and 15N: P < .001) was significantly better at reducing posterior humeral head translation than the DTA. Overall, increased glenohumeral stability was observed with increased force applied to the posterior deltoid flap in the Kouvalchouk procedure. The 15 N Kouvalchouk was most effective at preventing posterior humeral translation, and the difference was statistically significant compared with the 20% glenoid defect (P = .003), detached Kouvalchouk (P < .001), and 0N Kouvalchouk (P < .001). The 15 N Kouvalchouk procedure restored posterior shoulder joint stability to near normal levels, such that it was not significantly different from the intact state (P = .203).

CONCLUSIONS

The Kouvalchouk procedure with load applied to the deltoid was found to be biomechanically superior to the DTA for the management of posterior shoulder instability with associated bone loss. Additionally, the results confirmed the presence and effectiveness of the deltoid "hammock" effect.

Validation of mixed-reality surgical navigation for glenoid axis pin placement in shoulder arthroplasty using a cadaveric model

BACKGROUND

Mixed reality may offer an alternative for computer-assisted navigation in shoulder arthroplasty. The purpose of this study was to determine the accuracy and precision of mixed-reality guidance for the placement of the glenoid axis pin in cadaver specimens. This step is essential for accurate glenoid placement in total shoulder arthroplasty.

METHODS

Fourteen cadaveric shoulders underwent simulated shoulder replacement surgery by 7 experienced shoulder surgeons. The surgeons exposed the cadavers through a deltopectoral approach and then used mixed-reality surgical navigation to insert a guide pin in a preplanned position and trajectory in the glenoid. The mixed-reality system used the Microsoft Hololens 2 headset, navigation software, dedicated instruments with fiducial marker cubes, and a securing pin. Computed tomography scans obtained before and after the procedure were used to plan the surgeries and determine the difference between the planned and executed values for the entry point, version, and inclination. One specimen had to be discarded from the analysis because the guide pin was removed accidentally before obtaining the postprocedure computed tomography scan.

RESULTS

Regarding the navigated entry point on the glenoid, the mean difference between planned and executed values was 1.7 ± 0.8 mm; this difference was 1.2 ± 0.6 mm in the superior-inferior direction and 0.9 ± 0.8 mm in the anterior-posterior direction. The maximum deviation from the entry point for all 13 specimens analyzed was 3.1 mm. Regarding version, the mean difference between planned and executed version values was 1.6° ± 1.2°, with a maximum deviation in version for all 13 specimens of 4.1°. Regarding inclination, the mean angular difference was 1.7° ± 1.5°, with a maximum deviation in inclination of 5°.

CONCLUSIONS

The mixed-reality navigation system used in this study allowed surgeons to insert the glenoid guide pin on average within 2 mm from the planned entry point and within 2° of version and inclination. The navigated values did not exceed 3 mm or 5°, respectively, for any of the specimens analyzed. This approach may help surgeons more accurately place the definitive glenoid component.

Premorbid glenoid anatomy reconstruction from contralateral shoulder 3-dimensional measurements: a computed tomography scan analysis of 260 shoulders

BACKGROUND

Total shoulder arthroplasty (TSA) aims to reconstruct the premorbid anatomy of a pathologic shoulder. A healthy contralateral shoulder could be useful as a template in planning TSA. The symmetry between the left and right shoulders in healthy patients remains to be proved. The purpose of this study was to compare the 3-dimensional anatomy of the glenoid between sides in a healthy population.

METHODS

A multinational computed tomography scan database was retrospectively reviewed for all healthy bilateral shoulders in patients aged between 18 and 50 years. One hundred thirty pairs of healthy shoulder computed tomography scans were analyzed, and glenoid version, inclination, width, and height, as well as glenoid lateral offset and scapula lateral offset, were measured. All anatomic measures were computed with Blueprint, validated 3-dimensional planning software. The intraclass correlation coefficient was determined for each measure between left and right shoulders. The minimal detectable change (MDC) was calculated using the following formula: MDC=2×1.96×Standarderrorofmeasurement.

RESULTS

The comparison between 130 pairs of healthy scapulae showed statistically significant differences in absolute values between right and left glenoid version (-5.3° vs. -4.6°, P < .01), inclination (8.4° vs. 9.3°, P < .01), and width (25.6 mm vs. 25.4 mm, P < .01), as well as scapula offset (105.8 mm vs. 106.2 mm, P < .01). Glenoid height was comparable between right and left shoulders (33.3 mm vs. 33.3 mm, P = .9). The differences between the means were always inferior to the MDC regarding glenoid version, inclination, height, and width, as well as scapula offset. Very strong intraclass correlation coefficients between the left and right shoulders were found for all evaluated paired measures.

CONCLUSION

Healthy contralateral scapulae are highly reliable to predict inclination, height, width, and scapula offset and are reliable to predict version of a given scapula. Paired right and left scapulae were not statistically symmetrical regarding mean glenoid version, inclination, and width, as well as scapula offset. Nevertheless, the reported differences were not higher than the MDC for this cohort, confirming that healthy contralateral shoulders can be a useful template in TSA preoperative planning.

The effect of eccentric glenoid reaming in reverse shoulder artrhoplasty for glenohumeral osteoarthritis

Background

The objective of this study was to evaluate the abilitiy of eccentric reaming in reverse total shoulder arthroplasty (RSA), in patients with glenohumeral osteoarthritis (GHOA), to correct preoperative glenoid retroversion and to compare with cuff tear arthopaty (CTA) cases.

Methods

Fifty-nine patients who underwent RSA with GHOA or CTA diagnosis between 2013 and 2022 and who had pre- and postoperative computed tomography scans were included in the study. Preoperative glenoid version and postoperative glenoid component versions of 17 patients with GHOA and 40 patients with CTA were measured by Friedman method.

Results

The median preoperative glenoid versions in GHOA and CTA groups were measured as 16° and 4° retroverted respectively (p < 0.01). The median postoperative glenoid component versions in GHOA and CTA groups were 5° and 3° retroverted respectively (p = 0.09). The version change differences between the two groups varied significantly (p < 0.01).

Conclusions

GHOA is related with higher preoperative glenoid retroversion compared to CTA. However; with eccentric glenoid reaming, adequate version correction and similar postoperative glenoid version can be achieved in GHOA compared to CTA when performing a RSA.

Level of evidence

Level III. Retrospective study. Treatment study.

Humeral head size predicts baseplate lateralization in reverse shoulder arthroplasty: a comparative computer model study

Background

In reverse shoulder arthroplasty (RSA), the ideal combination of baseplate lateralization (BL), glenosphere size (GS), and glenosphere overhang (GOH) with a commonly used 145° neck shaft angle (NSA) is unclear. This is the first study evaluating correlations of body height (BH), humeral head size (HS), glenoid height (GH), and association of gender with best glenoid configurations for range of motion (ROM) maintaining anatomic lateralization (aLAT) for optimized muscle length in 145° and less distalized 135° RSA.

Methods

In this computer model study, 22 computed tomographies without joint narrowing were analyzed (11 male/female). A standardized semi-inlay 145° platform stem was combined with 20 glenoid configurations (baseplate [B] 25, 25 + 3/+6 lateralized [l], 29, 29 + 3/6l combined with glenosphere 36, 36 + 2 eccentric [e], 36 + 3l, 39, 39 + 3e, 39 + 3l , 42, 42 + 4e). Abduction-adduction, flexion-extension, external rotation-internal rotation, total ROM (TROM), and total notching relevant (TNR) ROM were computed, best TROM models respecting aLAT (-1 mm to +1 mm) and HS/GH recorded. Second, the 145° models (Ascend Flex stem; Stryker, Kalamazoo, MI, USA) were converted and compared to a 135° inlay RSA (New Perform stem; Stryker, Kalamazoo, MI, USA) maintaining GOH (6.5-7 mm) and aLAT.

Results

Best 145° models had eccentric glenospheres (mean BL: 3.5 mm, GOH 8.8 mm, GS 38.1 mm, distalization 23 mm). The 135° models had concentric glenospheres, mean BL 3.8 mm, GOH 6.9 mm, GS 39.7 mm, and distalization 14.1 mm. HS showed the strongest positive correlation with BL in 145° and 135° models (0.65/0.79). Despite reduced GOH in smaller females with a 135° NSA, adduction, external rotation, extension, TNR ROM, and TROM were significantly increased (P = .02, P = .005, P = .005, P = .004, P = .003), abduction however reduced (P = .02). The same trends were seen for males.

Conclusion

HS is a practical measure in surgery or preoperatively, and the strong positive correlation with BL is a useful planning aid. Despite reduction of GOH, conversion to a less distalized 135° NSAinlay design is powerful to maintain and even significantly increase all components of TNR ROM (extension/external rotation/adduction) in small females with the drawback of reduced abduction which may however be compensated by scapula motion. Lateralization with a less distalized 135° RSA optimizes muscle length, may facilitate subscapularis repair, and maintains highest rigid body motion.

Scapular morphology variation affects reverse total shoulder arthroplasty biomechanics. A predictive simulation study using statistical and musculoskeletal shoulder models

Reverse total shoulder arthroplasty (RTSA) accounts for over half of shoulder replacement surgeries. At present, the optimal position of RTSA components is unknown. Previous biomechanical studies have investigated the effect of construct placement to quantify mobility, stability and functionality postoperatively. While studies have provided valuable information on construct design and surgical placement, they have not systematically evaluated the importance of scapular morphology on biomechanical outcomes. The aim of this study was to assess the influence of scapular morphology variation on RTSA biomechanics using statistical models, musculoskeletal modeling and predictive simulation. The scapular geometry of a musculoskeletal model was altered across six modes of variation at four levels (±1 and ±3 SD) from a clinically derived statistical shape model. For each model, a standardized virtual surgery was performed to place RTSA components in the same relative position on each model then implemented in 50 predictive simulations of upward and lateral reaching tasks. Results showed morphology affected functional changes in the deltoid moment arms and recruitment for the two tasks. Variation of the anatomy that reduced the efficiency of the deltoids showed increased levels of muscle force production, joint load magnitude and shear. These findings suggest that scapular morphology plays an important role in postoperative biomechanical function of the shoulder with an implanted RTSA. Furthermore a "one-size-fits-all" approach for construct surgical placement may lead to suboptimal patient outcomes across a clinical population. Patient glenoid as well as scapular anatomy may need to be carefully considered when planning RTSA to optimize postoperative success.

The arthroscopic double-button Latarjet does not modify the static posterior translation of the humeral head

INTRODUCTION

The Latarjet procedure treats anterior instability of the shoulder and is based on a triple anterior lock, where the conjoint tendon straps the lower third of the subscapularis muscle. Excessive posterior translation of the humeral head is a known risk factor for shoulder osteoarthritis. No in vivo study has investigated the effect of the bone block on the posterior static translation of the humeral epiphysis. The purpose of this study was to evaluate the effect of the bone block on the static posterior translation of the humeral head. The hypothesis was that this procedure increased this translation.

MATERIALS AND METHODS

This retrospective study included patients treated arthroscopically for anterior shoulder instability by a double-button Latarjet. An independent examiner analyzed the CT scans preoperatively, at 15 days, and at least 6 months postoperatively according to a standardized protocol. The analysis focused on the position of the bone block in the axial and coronal planes relative to the glenoid. The posterior translation was automatically calculated using the Blueprint© planning software.

RESULTS

Thirty-five patients were included with a mean age of 25 years (16-43), according to a 4M/1F sex ratio. The graft was perfectly flush to the subchondral bone in 63% (n=22) of cases and subequatorial in 91% (n=32). Preoperative posterior humeral translation was 52%. The mean immediate postoperative posterior humeral translation was 56%, and 57% at more than 6 months. The change in mean posterior humeral translation between preoperative/6 months was +0.94% [-20%; +12%] (p=0.29) and immediate postoperative/6 months +0.34% [-18%; +15%] (p=0.84). Gender, hypermobility and the axial position of the bone block did not influence the change in posterior humeral translation. The equatorial position of the bone block appeared to increase posterior humeral translation by +10%±5.2% [-0.427; 20.823] (p=0.07).

CONCLUSION

This work refutes our initial hypothesis. The change in static posterior humeral translation after arthroscopic Latarjet bone block remains stable at more than 6 months of follow-up. This procedure does not alter the anatomical position of the humeral head in relation to the glenoid. On the other hand, a more cranial positioning of the bone block could have an influence.

LEVEL OF EVIDENCE

IV.

Systematic review of computed tomography parameters used for the assessment of subchondral bone in osteoarthritis

OBJECTIVE

To systematically review the published parameters for the assessment of subchondral bone in human osteoarthritis (OA) using computed tomography (CT) and gain an overview of current practices and standards.

DESIGN

A literature search of Medline, Embase and Cochrane Library databases was performed with search strategies tailored to each database (search from 2010 to January 2023). The search results were screened independently by two reviewers against pre-determined inclusion and exclusion criteria. Studies were deemed eligible if conducted in vivo/ex vivo in human adults (>18 years) using any type of CT to assess subchondral bone in OA. Extracted data from eligible studies were compiled in a qualitative summary and formal narrative synthesis.

RESULTS

This analysis included 202 studies. Four groups of CT modalities were identified to have been used for subchondral bone assessment in OA across nine anatomical locations. Subchondral bone parameters measuring similar features of OA were combined in six categories: (i) microstructure, (ii) bone adaptation, (iii) gross morphology (iv) mineralisation, (v) joint space, and (vi) mechanical properties.

CONCLUSIONS

Clinically meaningful parameter categories were identified as well as categories with the potential to become relevant in the clinical field. Furthermore, we stress the importance of quantification of parameters to improve their sensitivity and reliability for the evaluation of OA disease progression and the need for standardised measurement methods to improve their clinical value.

Post-operative Baseplate Radiographic Evaluation Using Routine pre-Operative CT

Background

There is limited data evaluating post-operative component position and fixation in reverse shoulder arthroplasty (RSA). Therefore, the purpose of this study was to evaluate baseplate position and fixation using routine pre-operative CT and post-operative radiographs.

Methods

A retrospective analysis of a series consecutive patient who underwent primary RSA was performed. Pre-operative and post-operative glenoid retroversion and inclination were measured using radiographs aligned with projection silhouettes of 3D scapula models in Mimics software. Baseplate retroversion and inclination were measured followed by evaluating for the presence of radiolucent lines (RLLs).

Results

Twenty-four patients met inclusion criteria. The average age was 73.4 ± 10.7 years (range, 45-89 years). Radiographic follow-up was 3.4 ± 1.3 years. Post-operative glenoid baseplate retroversion was 2 ± 10 degrees (range, 30 to -9). Post-operative glenoid baseplate inclination was 3.8 ± 9.1 (range, -13 to 19). Five (21%) RSAs had baseplate retroversion >10 degrees. Follow-up radiographs revealed no RLLs around the baseplate, central post, or peripheral screws in any patient.

Conclusions

Pre-operative CT imaging enabled evaluation of baseplate component placement and fixation on post-operative radiographs. Baseplate version was within 10 degrees of neutral in 79% (19/24) of patients. No RLLs or loss of fixation were found in any cases.

Level of Evidence

Level IV: Diagnostic Study.

BIO-RSA vs. metal-augmented baseplate in shoulder osteoarthritis with multiplanar glenoid deformity: a comparative study of radiographic findings and patient outcomes

BACKGROUND

Reverse shoulder arthroplasty (RSA) requiring extensive reaming to address severe glenoid bone loss increases the risk of glenoid medialization and baseplate failure. We hypothesized that (1) metal-augmented baseplate prevents the medialization of the joint line and preserves glenoid bone stock similarly to bony increased-offset (BIO)-RSA and (2) bone graft viability and healing in BIO-RSA patients become compromised over time.

MATERIALS AND METHODS

Eighty-one patients (83 shoulders) underwent glenoid lateralization with bone (BIO-RSA group, 44) or metal-augmented baseplate (metallic increased-offset [MIO]-RSA group, 39) and a minimum follow-up of 24 months were included. The orientation and direction of glenoid erosion was identified and recorded using computerized 3D planning. Active range of motion, and the Western Ontario Osteoarthritis of the Shoulder (WOOS) index were assessed before arthroplasty and at the last follow-up visits. Radiographic changes around the glenoid and humeral components were assessed. Healing and thickness of bone graft were evaluated by predefined criteria. Postoperative global glenoid inclination (β angle) and retroversion were also measured.

RESULTS

Delta scores of active anterior elevation were higher in the MIO-RSA group (P = .027). The differences in the other planes of shoulder motion and in WOOS index scores between the groups were not significant. Preoperative glenoid retroversion was higher in BIO-RSA patients, and glenoid inclination was similar in both groups. Type B2 and B3 glenoids had a posterior-central (91%) and posterior-superior (90%) erosion with a mean posterior humeral head subluxation of 76% and 78%, respectively. The direction of erosion in type E2 and E3 glenoids was posterior-superior, with a mean posterior humeral head subluxation of 74%. The rate of high position of the glenosphere was higher in the BIO-RSA group (P = .022), whereas the values of β angle and postoperative retroversion were similar in the 2 groups. BIO-RSA group showed radiolucent lines <2 mm around the bone graft in 16 patients (36.4%) and decreased thickness in 15 (34.1%). Incomplete baseplate seating was found in 4 MIO-RSA patients (10%). We found higher rates of humerus condensation lines in MIO-RSA patients (P = .01) and higher rates of cortical thinning and tuberosity resorption in the BIO-RSA group (P = .027 and P = .004, respectively).

CONCLUSION

Metal-augmented glenoid is a suitable alternative to BIO-RSA to preserve bone and prevent the medialization of the joint line in arthritic glenoid with multiplanar glenoid deformity. Bone and metal augmentation provided satisfactory clinical outcomes. Bone graft resorption in BIO-RSA patients raise concern about the risk of baseplate loosening and requires further long-term studies.

Patients who have intraoperative deviations in their preoperative plan have inferior clinical and radiographic outcomes after anatomic total shoulder arthroplasty

BACKGROUND

Three-dimensional computed tomography preoperative planning has become adopted among shoulder arthroplasty surgeons. Prior studies have not examined outcomes in patients in whom the surgeon implanted prostheses that deviated from the preoperative plan compared with patients in whom the surgeon followed the preoperative plan. The hypothesis of this study was that clinical and radiographic outcomes would be equivalent between patients undergoing anatomic total shoulder arthroplasty that had a deviation in the components predicted in the preoperative plan and patients who did not have a change in the components predicted in the preoperative plan.

METHODS

A retrospective review of patients who had preoperative planning for anatomic total shoulder arthroplasty from March 2017 through October 2022 was performed. Patients were stratified into 2 groups: patients in whom the surgeon used components that deviated from those anticipated by the preoperative plan (changed group), and patients in whom the surgeon used all of the components anticipated by the preoperative plan (planned group). Patient-determined outcomes including the Western Ontario Osteoarthritis Index, American Shoulder and Elbow Surgeons score, Single Assessment Numeric Evaluation, Simple Shoulder Test (SST), and Shoulder Activity Level were recorded preoperatively, at 1 year, and at 2 years. Preoperative and 1-year postoperative range of motion was recorded. Radiographic parameters to assess restoration of proximal humeral anatomy included humeral head height, humeral neck angle, humeral centering on the glenoid, and postoperative restoration of the anatomic center of rotation.

RESULTS

A total of 159 patients had intraoperative changes to their preoperative plan, and 136 patients underwent arthroplasty without changes to their preoperative plan. The planned group had higher scores than the group that had a deviation in the preoperative plan for every patient-determined outcome metric at every postoperative time point with statistically significant improvements found in the SST and Single Assessment Numeric Evaluation at 1-year and the SST and American Shoulder and Elbow Surgeons score at 2-year follow-up. No differences were found in range of motion metrics between the groups. Patients who did not have a deviation in their preoperative plan had more optimal restoration of their postoperative radiographic center of rotation than patients who did have a deviation in their preoperative plan.

CONCLUSIONS

Patients who have intraoperative changes to their preoperative plan have (1) inferior postoperative patient-determined outcome scores at 1 and 2 years after surgery and (2) a larger deviation in the postoperative radiographic restoration of the humeral center of rotation than patients who did not have intraoperative changes from the initial plan.

Three-Dimensional Measurement of Proximal Humerus Fractures Displacement: A Computerized Analysis

Neer's classification for proximal humerus fractures (PHFs) uses 10 mm and 45° thresholds to distinguish displaced fragments. While this system was originally developed referencing 2D X-rays, fracture displacements occur in three dimensions. Our work aimed to develop a standardized and reliable computerized method for measuring PHF 3D spatial displacements. CT scans of 77 PHFs were analyzed. A statistical shape model (SSM) was used to generate the pre-fracture humerus. This predicted proximal humerus was then used as a "layer" to manually reduce fragments to their native positions and quantify translation and rotation in three dimensions. 3D computerized measurements could be calculated for 96% of fractures and revealed that 47% of PHFs were displaced according to Neer's criteria. Valgus and varus head rotations in the coronal plane were present in 39% and 45% of cases; these were greater than 45° in 8% of cases and were always associated with axial and sagittal rotations. When compared to 3D measurements, 2D methods underestimated the displacement of tuberosity fragments and did not accurately assess rotational displacements. The use of 3D measurements of fracture displacement is feasible with a computerized method and may help further refine PHF analysis and surgical planning.

Design of well-matched end-structure of anatomical proximal femoral locking plate based on computer-assisted imaging combined with 3D printing technology: a quality improvement study

BACKGROUND

The extramedullary locking plate system was the common internal fixation method for hip fractures. However, common plates were poorly matched to femur, which was because they were designed based on anatomical parameters of the Western populations. Therefore, the aim was to design an end-structure of the anatomical proximal femoral locking plate that closely matched the anatomy of the Chinese population.

MATERIALS AND METHODS

From January 2010 to December 2021, consecutive patients aged 18 years and older who underwent a full-length computed tomography scan of the femur were included. The end-structure (male and female model) of the anatomical proximal femoral locking plate was designed based on anatomical parameters of femurs that were measured in three-dimensional space using computer-assisted virtual technology. The match degree between the end-structure and femur were evaluated. Inter-observer and intra-observer agreement for the evaluation of match degree was assessed. The matching evaluation based on a three-dimensional printing model was regarded as the gold standard to assess the reliability.

RESULTS

A total of 1672 patients were included, with 701 men and 971 women. Significant differences were seen between male and female for all parameters of the proximal femur (all P <0.001). All match degree of end-structure was over 90%. Inter-observer and intra-observer agreement was almost perfect (all kappa value, >0.81). The sensitivity, specificity, and percentage of correct interpretation of matching evaluation in the computer-assisted virtual model was all greater than 95%. From femur reconstruction to completion of internal fixation matching, the process takes about 3 min. Moreover, reconstruction, measurement, and matching were all completed in one system.

CONCLUSIONS

The results showed that based on the larger sample of femoral anatomical parameters, a highly matching end-structure of anatomical proximal femoral locking plate for Chinese population could be designed with use of computer-assisted imaging technology.

The Real Post-Operative Range of Motion Differs from the Virtual Pre-Operative Planned Range of Motion in Reverse Shoulder Arthroplasty

INTRODUCTION

The purpose of this study was to analyze the real range of motion (RoM) measured in patients operated on for reverse shoulder arthroplasty (RSA) and compare it to the virtual RoM provided by the preoperative planning software.

HYPOTHESIS

There was a difference between virtual and real RoM, which can be explained by different factors, specifically the scapula-thoracic (ST) joint.

METHODS

Twenty patients with RSA were assessed at a minimum follow-up of 18 months. Passive RoM in forward elevation abduction, without and with manually locking the ST joint, and in external rotation with arm at side were recorded. The humerus, scapula, and implants were manually segmented on post-operative CTs. Post-operative bony structures were registered to preoperative bony elements. From this registration, a post-operative plan corresponding to the real post-operative implant positioning was generated and the corresponding virtual RoM analysis was recorded. On the post-operative anteroposterior X-rays and 2D-CT coronal planning view, the glenoid horizontal line angle (GH), the metaphyseal horizontal line angle (MH), and the gleno-metaphyseal angle (GMA) were measured to assess the extrinsic glenoid inclination, as well as the relative position of the humeral and glenoid components.

RESULTS

There were some significant differences between virtual and post-operative passive abduction and forward elevation, with (55° and 50°, p < 0.0001) or without ST joint participation (15° and 27°, p < 0.002). For external rotation with arm at side, there was no significant difference between planning (24° ± 26°) and post-operative clinical observation (19° ± 12°) (p = 0.38). For the angle measurements, the GMA was significantly higher (42.8° ± 15.2° vs. 29.1°± 18.2°, p < 0.0001), and the GH angle, significantly lower on the virtual planning (85.2° ± 8.8° vs. 99.5° ± 12.5°, p < 0.0001), while the MH was not different (p = 0.33).

CONCLUSIONS

The virtual RoM given by the planning software used in this study differs from the real post-operative passive RoM, except for external rotation. This can be explained by the lack of ST joint and soft tissues simulation. However, in focusing on the virtual GH participation, the simulation looks informative. Some modifications between the glenoid and humerus starting positions before running the motion analysis could be provided for making it more realistic and predictive of the RSA functional results.

LEVEL OF EVIDENCE

III.

Scapulohumeral rhythm in shoulders with reverse shoulder arthroplasty measured with a new portable three-dimensional scapular kinematics assessment system

BACKGROUND

Reverse shoulder arthroplasty (RSA) is a valid and increasingly popular treatment option in eccentric arthrosis and cuff arthropathy. We know that the deltoid is the motor of RSA. However, the role of scapular motion has been poorly documented in the literature. The aim of our study is to analyze and quantify the role of the scapular contribution in the functional outcome of patients undergoing RSA.

MATERIALS AND METHODS

Fourteen patients who underwent primary RSA were included in the study. In all cases, a reverse prosthesis with lateralizing stem was implanted. All patients underwent clinical examination, video recording, and motion analysis. X-ray and postoperative CT examinations were collected to evaluate positioning and any loosening. ShowMotion (NCS Lab srl, Modena, Italy) 3D kinematic tracking system was used to evaluate and measure the scapular motion in 3 planes.

RESULTS

All patients show substantial amount of posterior tilting and lateral rotation starting at 30° in forward elevation. A further difference is the anticipation of the retraction during the range of motion in the RSA side. The contribution of scapular motion in the RSA shoulder was greater than in the healthy shoulder. In patients with bilateral RSA, the contribution of scapular motion was higher in tilting and lateral rotation in the worse shoulder side in terms of range of motion. This means that to compensate for the loss of glenohumeral motion in RSA, more scapula-thoracic motion is needed to obtain the same thoraco-humeral elevation angle.

CONCLUSIONS

In the light of what has been measured, the post-RSA scapular kinematics has typical characteristics that must be achieved in order to obtain a good functional outcome. We can conclude that on the RSA side, the patients anticipate upward rotation both in flexion and abduction. The contribution of the upward rotation to elevation in the RSA group is therefore more significant. In addition to this, to facilitate elevation movements, there is an anticipation of the scapular retraction and a more prominent tilt resulting in different scapular kinematics. The analysis of scapular motion could be useful in the postoperative follow-up of patients undergoing RSA surgery and improve adaptative physiotherapy protocols. It potentially can even be included in future arthroplasty planning systems.

Can We Completely Trust in Automated Software for Preoperative Planning of Shoulder Arthroplasty? Software Update May Modify Glenoid Version, Glenoid Inclination and Humeral Head Subluxation Values

Background: The purpose of this study was to evaluate the impact of software updating on measurements of the glenoid inclination and version, along with humeral head subluxation performed by an automated 3D planning program. The hypothesis was that the software update could significantly modify the values of the glenoid inclination and version, as well as of the humeral head subluxation. Methods: A comprehensive pool of 76 shoulder computed tomography (CT) scans of patients who underwent total shoulder arthroplasty (TSA) or reverse total shoulder arthroplasty (RTSA) were analyzed with the automated program Blueprint in 2018 and again in 2020 after a software update. Results: A statistically significant difference of 8.1 ± 8.2 and 5.4 ± 7.8 (mean difference of −2.8 ± 5.0, p < 0.001) was indeed reached when comparing the mean glenoid inclination achieved with Blueprint 2018 and Blueprint 2020, respectively. The glenoid version, as well as the humeral head subluxation evaluations, were not significantly different between the two software versions, with mean values being −9.4 ± 8.9 and −9.0 ± 7.4 and 60.1 ± 12.6 and 61.8 ± 12.0, respectively (p = 0.708 and p = 0.115, respectively). In 22% of CT scans, the software update determined a variation of the glenoid inclination of more than 5° or 10°. Conclusion: The present study shows the software update of an automated preoperative planning program may significantly modify the values of glenoid inclination. Even though without a significant difference, variations were also found for the glenoid version and humeral head subluxation. Accordingly, these results should further advise surgeons to carefully and critically evaluate data acquired with automated software.

Three-dimensional morphometric analysis of glenoid in the Indonesian population and its clinical significance

Background

Understanding glenoid morphometry is important in shoulder prosthetic replacement surgery. In total and reverse shoulder arthroplasty, the size of the implants has to be determined according to the morphometry of the shoulder. However, there has been no known data on glenoid morphometry in the Indonesian population.

Methods

Seventy-four computed tomography scans of asymptomatic shoulders were obtained from the medical databases of a third referral hospital in Jakarta. Mimics Research 21.0 was used to reconstruct 3D models of the scapula from the DICOM files. The morphometry parameters included were glenoid fossa height (GFH), maximum glenoid fossa width (MGW), glenoid width at center of the glenoid fossa (CGW), vertical distance between maximum width and center (VDMC), glenoid version angle (GVA), glenoid inclination (GI), glenopolar angle (GPA), glenoid vault depth (GVD), coracoid length (CL), coracoid midpoint length (CML), coracoid tip height (CTH) and width (CTW), and coracoid midpoint height (CMH) and width (CMW).

Results

Our study found the average Indonesian GFH was 30.24 mm, the MGW was 24.03 mm, the CGW was 22.46 mm, the VDMC was 3.67 mm, the GPA was 42.76°, the GVD 18.8 mm, the GVA was 2.39° retroverted, the GI was 3.15° superiorly inclined, the CL was 37.76 mm, the CML was 18.89 mm, the CTW was 13.31 mm, the CTH was 8.52 mm, the CMW was 14.21 mm, and the CMH was 10.46 mm. All parameters except VDMC, GVA, and GI showed significant differences between male and female subjects Meanwhile, there was no significant difference in dimension and orientation of the glenoid and coracoid between the right and left shoulder.

Conclusion

Our study showed a lower value of MGW, GFH, and GVD compared to other Asian ethnicities. These results may be helpful in designing smaller prostheses suitable for Indonesian glenoids.

Finite element analysis of titanium anatomic plate and titanium reconstructive plate for treatment of extra-articular fractures of the scapula

BACKGROUND

Due to the lack of postoperative reporting outcomes and bio-mechanical studies, an optimal management of scapular fractures has not been well-established in clinical treatment, even though there are many options available. This study aimed to compare the stability of the new titanium anatomic and traditional titanium reconstructive plates for extra-articular scapular fractures through finite element analysis.

METHODS

Two models of scapular assembly were constructed, including one anatomic plate (AP model) and one reconstructive plate (RP model). After meshing, material parameter, and boundary condition settings, we applied four loading conditions to simulate forces acting on the scapula and osteosynthesis material. To evaluate the bio-mechanical properties, the equivalent von Mises stress, equivalent elastic strain, and total deformation were investigated.

RESULT

The stress and strain distribution of model AP has better performance than model RP, with more uniform and lower values. The maximum stress value of the scapula in model AP is smaller than that of the scapula in model RP (102.83 MPa vs. 166.71 MPa). The maximum stress of the anatomic plate is half that of the reconstructive plate (218.34 MPa vs. 416.01 MPa). The maximum strain of the scapula in model AP is smaller than that of the scapula in model RP (0.0071 vs. 0.0106). The maximum strain of the anatomic plate is half that of the reconstructive plate (0.0019 vs. 0.0037). The maximum displacement of each model is all at the acromion, with a similar value (2.2947 mm vs. 1.8308 mm).

CONCLUSIONS

With sufficient bio-mechanical stability, the anatomic plate to support scapular fracture fragments was superior to that of the reconstructive plate.

Accuracy of reverse shoulder arthroplasty angle according to the size of the baseplate

BACKGROUND

Glenoid inclination must be assessed precisely during preoperative planning for reverse shoulder arthroplasty (RSA) to position the glenoid baseplate correctly. We hypothesized that a more dynamic measurement method would better match the diversity of glenoid heights in the population and the variety of commercialized glenoid baseplates. Our purpose was to describe a new method to measure the RSA angle accounting for the baseplate size.

METHODS

Computed tomography scans of 50 shoulders that underwent RSA for primary osteoarthritis or cuff tear arthropathy between June 2019 and February 2020 were included (mean age, 76 years). Three variants of the RSA angle were measured: the RSA angle as originally described by Boileau et al, the relative RSA 25 angle (which simulates the implantation of a 25-mm baseplate), and the relative RSA 29 angle (which simulates the implantation of a 29-mm baseplate). Measurements in the 2-dimensional true reformatted scapular plane were made by 3 independent operators.

RESULTS

The mean R-S distance (ie, distance between point R [intersection of supraspinatus fossa line with glenoid surface] and point S [inferior border of glenoid]) was 24.2 ± 4.0 mm. The mean RSA angle was 20.3° ± 8.4°, whereas the mean relative RSA 25 angle was 19.3° ± 7.8° and the mean relative RSA 29 angle was 15.6° ± 7.6°. The mean difference between the RSA angle and the relative RSA 25 angle was 1.0° ± 4.1° (P = .16). The mean difference between the RSA angle and the relative RSA 29 angle was 4.7° ± 3.8° (P < .0001). In half of the shoulders in our series, the difference between the RSA angle and the RSA 29 angle exceeded 5°.

CONCLUSION

The RSA angle is a reproducible measure of the inclination of the inferior part of the glenoid that is reliable in most cases for glenoid baseplates of 24-25 mm in height. However, surgeons should be aware that the RSA angle may overestimate the superior orientation of the inferior glenoid for baseplates of different sizes or for small- or large-stature patients. In these cases, the relative RSA angle adapted to the size of the baseplate more accurately evaluates the inclination of the inferior glenoid.

Pre-operative arthritic glenoid assessment: 3D automated planning software versus manual multiplanar measurements of version and inclination

Background

Preoperative CT-based planning is established in shoulder arthroplasty surgery. Automated planning software has become available to assist the surgeon and may increase reliability and efficiency. This study aims to evaluate the reliability of an automated 3-dimensional (3D) planning software package (Blueprint™ v2.1.5, Wright Medical Ltd) in the assessment of the arthritic shoulder against manual multiplanar measurement (MM).

Methods

74 CT studies acquired for preoperative shoulder arthroplasty planning were reviewed on two occasions by four different evaluators, taking manual measurement (MM) of glenoid version and inclination adjusted with multiplanar reformation and adhering to modified Freidman and Maurier methods. 15 scans were not processed by Blueprint due to incompatible scanning protocols or severe scapular dysmorphia. 59 Blueprint measures were compared with the manual data.

Results

Version: Intra-observer reliability of glenoid version MM was excellent (mean ICC 0.92). Inter-observer reliability between all four readers was good (ICC 0.89). A Bland-Altman analysis of Blueprint versus MM for version measurements demonstrated a mean pair difference of -5.77 (95% CI -7.25 to 4.29). Inclination: Intra-rater and inter-rater reliabilities were good (ICC 0.85 and 0.80 respectively). Blueprint and MM values for inclination followed a more convergent pattern than for version. Bland-Altman analysis for inclination did not show substantial bias, with a mean pair difference of 1.4 (95% CI -0.1 to 2.9).

Conclusion

Manual preoperative planning for shoulder arthroplasty is time consuming and requires experience. Automated 3D planning offers a consistent tool to assist the surgeon, notwithstanding intra-operative anatomical and technical variation, and margin of error. Surgeons should as ever be mindful of the specifics of a given automated program and our data quantified a bias for retroversion which may be important for measures close to the thresholds for augmentation or customised implants.

Three-Dimensional Scapular Border Method for Glenoid Version Measurements

Variations among methods to measure glenoid version have created uncertainty regarding which method provides the most consistent measurements of morphology. Greater deformity may also make accurate depiction of the native morphology more challenging. This study examined 4 current methods (Friedman, corrected Friedman, Ganapathi-Iannotti, and Matsumura) and an experimental scapular border-derived coordinate system method, to compare measurement inconsistencies between methods and reference systems and assess the impact of glenoid deformity on measured glenoid version.

Methods

Three-dimensional scapulae were created from computed tomography (CT) scans of 74 shoulders that had undergone arthroplasty (28 A2, 22 B2, 10 B3, and 14 C glenoids) and 34 shoulders that had not undergone arthroplasty. Glenoid version measurements were made in Mimics using the 4 methods. For the experimental method, scapulae were reconstructed, and 3 orthogonal global coordinate planes (GCPs) were derived from the medial and lateral borders. Version was measured as the angle between the sagittal reference plane and an anterior-posterior glenoid vector. The intraclass correlation coefficient (ICC) was calculated for the Friedman and corrected Friedman methods. Inconsistencies were assessed for all methods using the interquartile range, mean and standard deviation, and repeated-measures analysis of variance. Concordance correlation coefficients (CCCs) were calculated to assess agreement among the methods.

Results

Scapular plane-based methods (experimental, Friedman, and corrected Friedman) yielded an average version between -10° and -12°, with average measurement differences among these methods of <2°. Vault methods (Ganapathi-Iannotti and Matsumura) overestimated or underestimated version by an average of 5° to 7° compared with scapular plane-based methods, and showed significant differences of >12° when compared with each other. Scapular plane-based methods maintained consistency with increasing deformity.

Conclusions

The other methods of version measurement using the scapular planes as the reference were highly comparable with the corrected Friedman method. However, when the reference plane was the glenoid vault, version measurements were inconsistent with scapular plane-based methods, which is attributed to differences in the reference systems. In surgical planning, the coordinate system utilized will impact version measurements, which can result in variations in the planned surgical solutions. Additionally, as glenoid deformity increases, this variation resulting from the utilization of different coordinate systems is magnified.

3D-MRI versus 3D-CT in the evaluation of glenoid deformity in glenohumeral arthritis using Dixon 3D FLASH sequence

OBJECTIVE

To compare MRI with 3D reconstructions and 3D-CT with respect to assessment of glenoid wear in osteoarthritic shoulders.

METHODS

3D reconstructions were generated for CT and MR (utilizing the Dixon technique) imaging performed on 29 osteoarthritic shoulders. Two reviewers independently performed glenoid morphometric measurements and evaluated glenoid erosion. Mean differences between the two modalities were calculated. Inter-observer agreement was calculated using kappa coefficient.

RESULTS

The combined mean absolute difference (bias) in glenoid version between 3D-CT and 3D-MRI was 2.7° ± 1.6° (range 0.15-7.85, P value = 0.7). The combined mean absolute difference in glenoid inclination between 3D-CT and 3D-MRI was 6.8° ± 4.1° (range 0.8°-15.75°, P value = 0.17). No significant inter-reader variation in glenoid version and inclination measurements on 3D-CT and 3D-MRI was found (P > 0.05). The inter-reader reliability for both CT and MRI was high for Walch grading of glenoid bone loss (κ = 1, κ = 0.81, respectively).

CONCLUSIONS

3D-MRI is comparable to 3D-CT with respect to axial glenoid bone loss, as measured by glenoid version. However, for coronal bone loss estimation, measured by glenoid inclination, 3D-CT remains the gold standard. Thus, 3D-MR can be used as an alternative for preoperative assessment of glenoid version in arthritic shoulders.

Posteroinferior relevant scapular neck offset in reverse shoulder arthroplasty: key player for motion and friction-type impingement in a computer model

BACKGROUND

Range of motion (ROM) and prevention of notching remain a challenge for reverse shoulder arthroplasty (RSA). Both may be affected by the morphology of the scapula. The purpose of this study was to define anteroinferior (a) and posteroinferior (p) relevant scapular neck offset (RSNO) and to examine the hypothesis that pRSNO is significantly smaller than aRSNO, and influences rigid body motion (RBM). Adapting glenosphere implantation strategies may therefore be of value.

MATERIAL AND METHODS

In this computer model study, we used deidentified computed tomographic scans of 22 patients (11 male and 11 female; mean age: 72.9 years) with massive cuff tears without joint space narrowing. Eight RSA glenoid configurations were tested with a constant neck-shaft angle (145°). Two baseplate types (25 mm; 25 + 3 mm lateralized) and 4 glenospheres (GS) (36 mm; 36 +2 mm of eccentricity; 39 mm; 39 + 3 mm) were used. RSNO was defined as the standardized measurement of the horizontal distance from the inferior extent of the GS to the bony margin of the scapula after baseplate positioning (flush to inferior glenoid extent; neutral position: 0° inclination and 0° version-both software computed).

RESULTS

There was a highly significant difference between pRSNO and aRSNO for both genders (P < .001). pRSNO was always smaller than aRSNO. pRSNO was strongly correlated with external rotation (ERO: 0.84) and extension (EXT: 0.74) and moderately correlated with global ROM (GROM: 0.68). There was a moderately strong correlation between aRSNO and internal rotation (IRO: 0.69). pRSNO was strongly correlated with aRSNO, EXT, ERO, IRO, adduction (ADD) and GROM (0.82, 0.72, 0,8, 0.71, 0.82, 0.76) in female patients and with EXT and ERO (0.82, 0.89) in male patients. The median pRSNO allowing for at least 45° ERO and 40° EXT was 14.2 mm for men and 13.8 mm for women. For all patients and models, pRSNO ≥14 mm increased EXT, ERO, and GROM significantly compared with pRSNO <14 mm (P < .001). The combination of lateralization and inferior overhang (eccentricity) led to the most significant increase of pRSNO for each GS size (P < .001).

CONCLUSION

This is one of the first RSA modeling studies evaluating nonarthritic glenoids of both genders. The lateral scapular extent to glenoid relationship is asymmetric. pRSNO is always smaller than aRSNO for both genders and was a critical variable for EXT and ERO, demonstrating additional strong correlation with aRSNO, IRO, ADD, and GROM in female patients. pRSNO ≥14 mm was a safe value to prevent friction-type impingement. Combining increased glenosphere size, lateralization, and inferior overhang gives the best results in this computer-simulated setting.

Difference analysis of the glenoid centerline between 3D preoperative planning and 3D printed prosthesis manipulation in total shoulder arthroplasty

INTRODUCTION

Excessive version and inclination of the glenoid component during total shoulder arthroplasty can lead to glenohumeral instability, early loosening, and even failure. The orientation and position of the central pin determine the version and inclination of the glenoid component. The purpose of this study was to compare the differences in centerline position and orientation obtained using "3D preoperative planning based on the best-fit method for glenoid elements" and the surgeon's manipulation.

MATERIALS AND METHODS

Twenty-nine CT images of glenohumeral osteoarthritis of the shoulder were reconstructed into a 3D model, and a 3D printer was used to create an in vitro model for the surgeon to drill the center pin. The 3D shoulder model was also used for 3D preoperative planning (3DPP) using the best-fit method for glenoid elements. The in vitro model was scanned and the version, inclination and center position were measured to compare with the 3DPP results.

RESULTS

The respective mean inclinations (versions) of the surgeon and 3DPP were -2.63° ± 6.60 (2.87° ± 5.97) and -1.96° ± 4.24 (-3.21° ± 4.00), respectively. There was no significant difference in the inclination and version of the surgeon and 3DPP. For surgeons, the probability of the inclination and version being greater than 10° was 13.8% (4/29) and 10.3% (3/29), respectively. Compared to the 3DPP results, the surgeon's center position was shifted down an average of 1.63 mm. There was a significant difference in the center position of the surgeon and 3DPP (p < 0.05).

CONCLUSION

The central pin drilled by surgeons using general instruments was significantly lower than those defined using 3D preoperative planning and standard central definitions. 3D preoperative planning prevents the version and inclination of the centerline from exceeding safe values (± 10°).

Anatomical plane and transverse axis of the scapula: Reliability of manual positioning of the anatomical landmarks

Background

The aim of our study was to evaluate the accuracy of manual determination of the three key points defining the anatomical plane of the scapula, which conditions the reliability of planning software programs based on manual method.

Method

We included 82 scapula computed tomography scans (56 pathologic and 26 normal glenoid), excluding truncation and major three-dimensional artifact. Four observers independently picked the three key points for each case. Inter- and intra-observer agreement was calculated for each point, using the intraclass correlation method. The mean error (mm) between the observers was calculated as the diameter of the smallest sphere including the four chosen positions.

Results

Lower inter-observer agreement was found for the trigonum superoinferior position and for the glenoid center anteroposterior position. The mean positioning error between the four observers was 6.9 mm for the trigonum point, and error greater than 10 mm was recorded in 25% of the cases. The mean positioning error was 3.5 mm for the glenoid center in altered glenoid, compared to 1.8 mm for normal glenoid.

Discussion

Manual determination of an anatomical plane of the scapula suffers from inaccuracy especially due to the variability in trigonum picking, and in a lesser extent, to the variability of glenoid center picking in altered glenoid.

The Effect of Glenoid Version on Glenohumeral Instability

In recent years, an appreciation for the dynamic relationship between glenoid and humeral-sided bone loss and its importance to the pathomechanics of glenohumeral instability has substantially affected modern treatment algorithms. However, comparatively less attention has been paid to the influence of glenoid version on glenohumeral instability. Limited biomechanical data suggest that alterations in glenoid version may affect the forces necessary to destabilize the glenohumeral joint. However, this phenomenon has not been consistently corroborated by the results of clinical studies. Although increased glenoid retroversion may represent an independent risk factor for posterior glenohumeral instability, this relationship has not been reliably observed in the setting of anterior glenohumeral instability. Similarly, the effect of glenoid version on the failure rates of surgical stabilization procedures remains poorly understood.

Glenoid Bone Loss Determination: Validity and Reliability of the Constellation Technique Versus the Sagittal Best Fit Circle Technique

OBJECTIVE

To propose a new method for glenoid bone loss measurement, the constellation technique (CST); determine its reliability and accuracy; and compare the validity of CST with that of the conventional technique (CVT) and standard measurements for ratio calculation.

MATERIALS AND METHODS

Sixty shoulders with intact glenoids and no glenohumeral instability and arthritis underwent CT scans. Simulated osteotomies were conducted on the 3D models of glenoids at two cutting locations, expressed as clock face times (2:30-4:20; 1:30-5:00). Two experienced surgeons compared three methods for glenoid bone loss measurement; CVT (best-fit circle), CST ('5S' steps), and standard measurement. Eight undergraduates remeasured five randomly chosen shoulders with moderate to severe bone loss. Intraclass correlation coefficients (ICCs) were calculated for raters.

RESULTS

With a defect range between 2:30 and 4:20, all 60 glenoids demonstrated minimal bone loss (< 15%); while between 1:30 and 5:00, 42 shoulders were with moderate bone loss (15-20%), and 18 shoulders with severe bone loss (≥ 20%). For experienced raters, no significant differences were noted between protocos for all categories of bone loss (p ≥ 0.051), with good inter- and intraobserver reliability indicated by ICC. For novice raters, post hoc Tukey analysis found that CST was more accurate in one patient with a standard mean bone loss of 23.2% ± 1.9% compared with CVT.

CONCLUSION

The CST turned the key step of glenoid defect evaluation from deciding an en face view to determining the glenoid inferior rim. The protocol is simple, accurate, and reproducible, especially for novice raters.

Stem size prediction in shoulder arthroplasty with preoperative 3D planning

INTRODUCTION

Three-dimensional surgical planning software provides virtual reconstructions of the shoulder with automated joint indices for a preoperative case assessment. The aim of this single center study was to evaluate the concordance between the preoperatively selected humeral components and the final implants used in shoulder arthroplasty.

METHODS

129 cases who had undergone anatomic (n = 16) or reverse shoulder arthroplasty (n = 117) using the same type of uncemented short stem implant and were included for review in this study. The type of arthroplasty, stem size, stem inclination, tray-offset and liner-thickness were noted preoperatively and compared to the final implant specifications used in surgery.

RESULTS

The type of arthroplasty matched the surgical plan in 99.2% of cases, as one case was converted from RSA to TSA. The concordance of planned to implanted stem size was 44.2% and the planned size was in range of one adjacent size in 87.6% of cases. Stem inclination in TSA matched the surgical plan in 50% of cases. Tray offset in RSA was predicted correctly in 65% and liner-thickness matched the surgical plan in 98.3% of cases.

CONCLUSION

Despite a low degree of concordance of planned to implanted stem sizes of 44.2%, the choice of stem size was found to be in range of one adjacent size in 87.6% of cases. Further investigations of other contributing factors are necessary to increase the accuracy of the preoperative selection of humeral implants.

LEVEL OF EVIDENCE

level IV, retrospective case study.

Anatomic measurement of osseous parameters of the glenoid

The angle and position of the scapular glenoid are important in shoulder mechanics, the interpretation of diseases, and planning shoulder replacement surgery. In total shoulder replacement, understanding the bony parameters of the glenoid is also of considerable guiding significance for designing implant size and improving material adaptability. To compare glenoid parameters measured from skeletal scapula specimens with those measured by 3D modeling of CT scanning images, analyze correlations between these data, and draw conclusions to guide clinical treatment of shoulder joint injury and total shoulder joint replacement. The data of manual and CT measurements from the same Chinese dry glenoid was compared. Three-dimensional measurement data were collected from the Japanese population and compared with the Chinese population data generated in this study. There were no significant differences between manual measurement and CT measurement in the inclination angle, glenopolar angle, anteroposterior transverse diameter, upper to lower vertical diameter, and depth of the glenoid (P = 0.288, 0.524, 0.111, 0.194, and 0.055, respectively). Further, there were no significant differences between Japanese and Chinese glenoid bones in the upper and lower vertical diameters or anteroposterior transverse diameters (P > 0.05). There were no significant differences between CT and manual measurements, suggesting that the CT method may provide measurements very close to the actual specimen size. This result, however, indicated that the measurer should be careful when measuring the depth of the glenoid.

Comparison of Simulated Low-Dose and Conventional-Dose CT for Preoperative Planning in Shoulder Arthroplasty

BACKGROUND

Shoulder computed tomography (CT) is commonly utilized in preoperative planning for total shoulder arthroplasty. Conventional-dose shoulder CT may expose patients to more ionizing radiation than is necessary to provide high-quality images for this procedure. The purpose of this study was to evaluate the utility of simulated low-dose CT images for preoperative planning using manual measurements and common preoperative planning software.

METHODS

Eighteen shoulder CT scans obtained for preoperative arthroplasty planning were used to generate CT images as if they had been acquired at reduced radiation dose (RD) levels of 75%, 50%, and 25% using a simulation technique that mimics decreased x-ray tube current. This technique was validated by quantitative comparison of simulated low-dose scans of a cadaver with actual low-dose scans. Glenoid version, glenoid inclination, and humeral head subluxation were measured using 2 commercially available software platforms and were also measured manually by 3 physicians. These measurements were then analyzed for agreement across RD levels for each patient. Tolerances of 5° of glenoid version, 5° of glenoid inclination, and 10% humeral head subluxation were used as equivalent for preoperative planning purposes.

RESULTS

At all RD levels evaluated, the preoperative planning software successfully segmented the CT images. Semiautomated software measurement of 25% RD images was within tolerances in 99.1% of measurements; for 50% RD images, within tolerances in 96.3% of measurements; and for 75% RD images, within tolerances in 100% of measurements. Manual measurements of 25% RD images were within these tolerances in 95.1% of measurements; for 50% RD images, in 98.8% of measurements; and for 75% RD images, in 99.4% of measurements.

CONCLUSIONS

Simulated low-dose CT images were sufficient for reliable measurement of glenoid version, glenoid inclination, and humeral head subluxation by preoperative planning software as well as by physician-observers. These findings suggest the potential for substantial reduction in RD in preoperative shoulder CT scans without compromising surgical planning.

CLINICAL RELEVANCE

The adoption of low-dose techniques in preoperative shoulder CT may lower radiation exposure for patients undergoing shoulder arthroplasty, without compromising image quality.

A comparative analysis of titanium anatomic plate and titanium reconstructive plate for treatment of extra-articular fractures of the scapula (Miller types IIb, IIc, and IV)

BACKGROUND

Because of the irregular shape of the scapula and the different types of fractures, a standard internal fixation device is lacking in clinical practice, even though there are many options available. This study aimed to compare the therapeutic efficacy of titanium anatomic and reconstructive plates for extra-articular fractures of the scapula (Miller types IIb, IIc, and IV).

METHODS

A retrospective study of 41 patients who underwent treatment for extra-articular fractures of the scapula between March 2017 and March 2020 was conducted. Patients were divided into 2 groups based on the fixation device: titanium anatomic plate group (20 patients) and titanium reconstructive plate group (21 patients). After follow-up for 12-18 months, the general characteristics, perioperative characteristics, postoperative follow-up findings, and imaging data of the 2 groups were compared.

RESULTS

The surgical procedures were uneventful in both groups. The anatomic plate group significantly outperformed the reconstructive plate group with respect to surgical duration and intraoperative blood loss (P < .001). At 3-month postoperative follow-up, the Constant-Murley score (P = .026), shoulder flexion range of motion, and shoulder abduction range of motion in the anatomic plate group were all significantly better than those in the reconstructive plate group (P < .001). The postoperative Western Ontario Shoulder Instability scores of the 2 groups were similar. Imaging showed functional recovery and stable and reliable fixation in both groups. Time to bone union was similar in both groups (9.10 ± 1.25 weeks in anatomic plate group and 9.24 ± 1.41 weeks in reconstructive plate group, P = .742). No complications occurred in any patient, such as fixation failure, instability, or bone nonunion.

CONCLUSION

Surgeons should favorably consider titanium anatomic plates for the treatment of extra-articular scapular fractures owing to their clear efficacy associated with a shorter surgical time, less intraoperative blood loss, better fixation, and rapid short-term functional recovery.

Anatomic Total Shoulder Arthroplasty: Component Size Prediction with 3-Dimensional Pre-Operative Digital Planning

Background

The rate, complexity, and cost of total shoulder arthroplasty (TSA) continues to grow. Technology has advanced pre-operative templating. Reducing cost of TSA has positive impact for the patient, manufacturer, and hospital. The aim of this study was to evaluate the accuracy of implant size selection based on 3-D templating. Our hypothesis was that pre-operative templating would enable accurate implant prediction within one size.

Methods

Multicenter retrospective study of anatomic TSAs templated utilizing 3-D virtual planning technology. This program uses computed tomography (CT) scans allowing the surgeon to predict component sizes of the glenoid and humeral head and stem. Pre-operative templated implant size were compared to actual implant size at the time of surgery. Primary data analysis utilized unweighted Cohen's Kappa test.

Results

111 TSAs were analyzed from five surgeons. Pre-operative templated glenoid sizes were within one size of actual implant in 99% and exactly matched in 89%. For patients requiring a posterior glenoid augment (n = 14), 100% of implants were within one size of the template and 93% matched exactly. For stemless humeral components (n = 87) implanted, 98% matched the pre-operative template within one size with 79% exactly matched. For stemmed components (n = 24), 88% of cases were within one size of the preoperative plan and exactly matching in 83%. Humeral head diameter matched within one size of the pre-operative template in 84% of cases and exactly matched in 72%.

Conclusion

Pre-operative 3-D templating for TSAs can accurately predict glenoid and humeral component size. This study sets the groundwork for utilization of pre-operative 3-D templating as a potential method to reduce overall TSA costs by managing cost of implants, reducing inventory needs, and improving surgical efficiency.

Preoperative planning of baseplate position in reverse shoulder arthroplasty: Still no consensus on lateralization, version and inclination

INTRODUCTION

In the context of reverse shoulder arthroplasty, some parameters of glenoid baseplate placement follow established golden rules, while other parameters still have no consensus. The assessment of glenoid wear in the future location of the glenoid baseplate varies among surgeons. The objective of this study was to analyze the inter-observer reproducibility of glenoid baseplate 3D positioning during virtual pre-operative planning.

METHOD

Four shoulder surgeons planned the glenoid baseplate position of a reverse arthroplasty in the CT scans of 30 degenerative shoulders. The position of the glenoid guide pin entry point and the glenoid baseplate center was compared between surgeons. The baseplate's version and inclination were also analyzed.

RESULTS

The 3D positioning of the pin entry point was achieved within ± 4 mm for nearly 100% of the shoulders. The superoinferior, anteroposterior and mediolateral positions of the baseplate center were achieved within ± 2 mm for 77.2%, 67.8% and 39.4% of the plans, respectively. The 3D orientation of the glenoid baseplate within ± 10° was inconsistent between the four surgeons (weak agreement, K=0.31, p=0.17).

DISCUSSION

The placement of the glenoid guide pin was very consistent between surgeons. Conversely, there was little agreement on the lateralization, version and inclination criteria for positioning the glenoid baseplate between surgeons. These parameters need to be studied further in clinical practice to establish golden rules. Three-dimensional information from pre-operative planning is beneficial for assessing the glenoid deformity and for limiting its impact on the baseplate position achieved by different surgeons.

LEVEL OF EVIDENCE

III. Case control study.

What is the deviation in 3D preoperative planning software? A systematic review of concordance between plan and actual implant in reverse total shoulder arthroplasty

BACKGROUND

Three-dimensional (3D) preoperative planning software for reverse total shoulder arthroplasty (rTSA) has been implemented in recent years in order to increase accuracy, improve efficiency, and add value to the outcome. A comprehensive literature review is required to determine the utility of preoperative 3D planning software in guiding orthopedic surgeons for implant placement in rTSA. We hypothesize that implementation of 3D preoperative planning software in the setting of rTSA leads to high concordance with minimal deviation from the preoperative plan.

METHODS

A comprehensive and iterative literature review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) using the PubMed, Embase, OVID Medline, Scopus, Cinahl, Web of Science, and Cochrane databases for original English-language studies evaluating the impact of preoperative planning software usage on rTSA outcomes published from January 1, 2000, to present. Blinded reviewers conducted multiple screens. All included studies were graded based on level of evidence, and data concerning patient demographics and postoperative outcomes were extracted.

RESULTS

Nine articles met inclusion criteria (1 level II, 3 level III, and 5 level IV articles), including 415 patients and 422 shoulders. Of the patients who underwent rTSA, 235 were female and 140 were male, although 3 studies (n = 40) did not report sex breakdowns for rTSA patients. The average age was 72.7 years. Four studies (79 shoulders) reported implant final position as mean deviation from planned version and planned inclination. Six studies (n = 236) reported screw angle deviation, fixation, length, and concordance. Concordance with the preoperative plan was measured in 3 studies (n = 178), resulting in complete concordance of 90% (n = 100), arthroplasty type concordance (rTSA vs. TSA) of 100% (n = 100), and glenosphere size concordance between 93% (n = 100) and 88% (n = 76). For screw length concordance, baseplate screw matched by 81% (n = 76) and 100% (n = 2), and upper (n = 35) and lower (n = 35) screw length concordance was observed as 74% and 69%, respectively. The use of preoperative planning (n = 178) was associated with low deviation from preoperative plan, more 2-screw fixations, and longer average screw length in comparison with an unplanned cohort.

CONCLUSION

The use of preoperative planning software in the setting of rTSA results in minimal deviation from preoperative plan. High levels of concordance in screw angle, screw length, and glenosphere size were observed. Further prospective studies should be conducted to further substantiate these results.

Automatic surgical planning based on bone density assessment and path integral in cone space for reverse shoulder arthroplasty

PURPOSE

Reverse shoulder arthroplasty (RSA) is an effective surgery for severe shoulder joint diseases. Traditionally, the preoperative planning procedure of RSA is manually conducted by experienced surgeons, resulting in prolonged operating time and unreliable drilling paths of the prosthetic fixation screws. In this study, an automatic surgical planning algorithm for RSA was proposed to compute the optimal path of screw implantation.

METHODS

Firstly, a cone-shaped space containing alternative paths for each screw is generated using geometric parameters. Then, the volume constraint is applied to automatically remove inappropriate paths outside the bone boundary. Subsequently, the integral of grayscale value of the CT is used to evaluate the bone density and to compute the optimal solution. An automatic surgical planning software for RSA was also developed with the aforementioned algorithms.

RESULTS

Twenty-four clinical cases were used for preoperative planning to evaluate the accuracy and efficiency of the system. Results demonstrated that the angles among the prosthetic fixation screws were all within constraint angle(45°), and the stability rate of the planned prosthesis was 94.92%. The average time for the automatic planning algorithm was 4.39 s, and 83.96 s for the whole procedure. Repetitive experiments were also conducted to demonstrate the robustness of our system, and the variance of the stability coefficient was 0.027%.

CONCLUSIONS

In contrast to the cumbersome manual planning of the existing methods for RSA, our method requires only simple interaction operations. It enables efficient and precise automatic preoperative planning to simulate the ideal placement of the long prosthetic screws for the long-term stability of the prosthesis. In the future, it will have great clinical application prospects in RSA.

SciKit-SurgeryGlenoid, an Open Source Toolkit for Glenoid Version Measurement

Correct understanding of the geometry of the glenoid (the socket of the shoulder joint) is key to successful planning of shoulder replacement surgery. This surgery typically involves placing an implant in the shoulder joint to restore joint function. The most relevant geometry is the glenoid version, which is the angular orientation of the glenoid surface relative to the long axis of the scapula in the axial plane. However, measuring the glenoid version is not straightforward and there are multiple measurement methods in the literature and used in commercial planning software. In this paper we introduce SciKit-SurgeryGlenoid, an open source toolkit for the measurement of glenoid version. SciKit-SurgeryGlenoid contains implementations of the 4 most frequently used glenoid version measurement algorithms enabling easy and unbiased comparison of the different techniques. We present the results of using the software on 10 sets of pre-operative CT scans taken from patients who have subsequently undergone shoulder replacement surgery. We further compare these results with those obtained from a commercial implant planning software. SciKit-SurgeryGlenoid currently requires manual segmentation of the relevant anatomical features for each method. Future work will look at automating the segmentation process to build an automatic and repeatable pipeline from CT or radiograph to quantitative glenoid version measurement.

Risk of penetration of the baseplate peg in reverse total shoulder arthroplasty for an Asian population

PURPOSE

Baseplate positioning may affect clinical outcome after reverse total shoulder arthroplasty (RTSA). The aim of this study was to evaluate the risk of penetration of the baseplate peg in RTSA.

METHODS

Forty-four patients with rotator cuff arthropathy or massive rotator cuff tears were included. Using their computed tomography data, ten insertion patterns of the baseplate pegs were simulated. First, in the axial plane, the baseplate was placed perpendicular to the Friedman axis (Friedman placement) and parallel to the glenoid surface (glenoid placement). Second, each of these placements were classified into the following groups: The baseplate peg was placed 2 mm anterior to the long axis of the glenoid (group A2), 1 mm anterior (group A1), on the long axis (group C0), 1 mm posterior (group P1), and 2 mm posterior (group P2). Cases in which the baseplate peg was within the scapular neck were defined as non-penetration, and the non-penetration rates among each group were evaluated and compared between sexes, and their relationship with patient height was evaluated.

RESULTS

In both the Friedman and glenoid placements, the non-penetration rate was significantly higher in groups A2 (68.2% and 70.5%) and A1 (65.9% and 65.9%) compared with groups P1 (18.2% and 29.5%) and P2 (9.1% and 13.6%; p < 0.001) and in males than in females (p < 0.05). Furthermore, the non-penetration rate tended to be higher as the patient's height increased.

CONCLUSIONS

It is recommended that the baseplate peg be placed anterior to the long axis of the glenoid.

Variability and reliability of 2-dimensional vs. 3-dimensional glenoid version measurements with 3-dimensional preoperative planning software

BACKGROUND

Preoperative planning for total shoulder arthroplasty (TSA) may change according to the measured degree of glenoid version. Both 2-dimensional (2D) and 3-dimensional (3D) computed tomographic (CT) scans are used to measure glenoid version, with no consensus on which method is more accurate. However, it is generally accepted that 3D measurements are more reliable, yet most 3D reconstruction software currently in clinical use have never been directly compared to 2D. The purpose of this study is to directly compare 2D and 3D glenoid version measurements and determine the differences between the two.

METHODS

CT scans were performed preoperatively on 315 shoulders undergoing either anatomic or reverse TSA. 2D measurements of glenoid version were obtained manually using the Friedman method, whereas 3D measurements were obtained using the Equinoxe Planning Application (Exactech Inc.) 3D-reconstruction software. Negative version values indicate retroversion, whereas positive values indicate anteversion. Two observers collected the 2D measurements 2 separate times, and intra- and interobserver measurements were calculated. Groups were compared for variability using intraclass correlation coefficients (ICCs), and for differences in sample means using Student t tests. Additionally, samples were stratified by version value in order to better understand the potential sources of error between measurement techniques.

RESULTS

For the 2D measurements, intraobserver variability indicated excellent reproducibility for both observer 1 (ICC = 0.928, 95% confidence interval [CI] 0.911-0.942) and observer 2 (ICC = 0.964, 95% CI 0.955-0.971). Interobserver variability measurements also indicated excellent reproducibility (ICC = 0.915, 95% CI 0.778-0.956). The overall 2D version measurement average (-4.9° ± 10.3°) was significantly less retroverted than the 3D measurement average (-8.4° ± 9.1°) (P < .001), with 3D measurements yielding a more retroverted value 73% of the time. When stratified on the basis of version value with outliers excluded, there was no significant difference in the distribution of high-error samples within the data.

DISCUSSION

There was excellent reproducibility between the 2 observers in terms of both intra- and interobserver variability. The 3D measurement techniques were significantly more likely to return a more retroverted measurement, and high-error samples were evenly distributed throughout the data, indicating that there were no discernable trends in the degree of error observed. Shoulder surgeons should be aware that different glenoid version measurement strategies can yield different version measurements, as these can affect preoperative planning and surgeon decision making.

The Use of Preoperative Planning to Decrease Costs and Increase Efficiency in the OR

Background

Shoulder arthroplasty (SA) incurs up to $1.8B per year in societal costs. With the increasing demand for SA and the steady decrease of annual reimbursements for orthopedic procedures, it has become crucial to control costs. In SA, there has been an interest in using preoperative planning software to improve accuracy in positioning and implant selection, ultimately optimizing outcomes. However, the use of preoperative planning to increase efficiency has not been studied. The purpose of this study was to determine if preoperative planning could increase efficiency and decrease costs in the operating room.

Methods

This retrospective review included 94 patients who underwent shoulder arthroplasty and had a CT scan with a preoperative plan by a single orthopedic surgeon between 2017 and 2020. The patients were divided based on the use of the preoperative plan during surgery. Group 1 included 65 patients with a preoperative plan used during surgery, and group 2 included 29 patients without a preoperative plan utilized during surgery. Average preparation time, surgical time, time in the operating room, the number of trays sterilized, and postoperative outcomes were analyzed between the two groups. Subanalysis was done to find a statistical difference in the cost of sterilization for both groups.

Results

The cohort had 55% males, with an average age of 71 years and an average BMI of 29.9. There were no significant differences between the groups for age, BMI, or ASA class. There was no significant difference between groups in preparation time (group 1: 53.3 min, group 2: 53.1 min P = .924), surgical time (group 1: 119.7 min, group 2: 111.9 min; P = .25), or time in the OR (group 1: 183.2 min, group 2: 173.2 min; P = .156). There was a statistical difference in the number of trays (5 vs. 8; P < .01) and cost of sterilization between groups ($487.30 vs. $842.86; P < .01). No correlation between the number of trays and preparation time (group 1: −0.05, group 2: −0.28) or trays and surgical time was found for either group (group 1: r = −0.31, group 2: r = −0.22). There were no significant differences in postoperative outcomes between the groups.

Conclusion

While preoperative planning did not reduce time in the OR for shoulder arthroplasty, it was correlated to a significant reduction in the number and cost of sterilized trays with comparable postoperative outcomes.

Walch B2 glenoids. 2D vs 3D comparison of humeral head subluxation and glenoid retroversion

Background

The posterior subluxation and glenoid version in Walch B2 glenoids are routinely assessed by 2-dimensional (2D) computed tomography (CT). Different methods of calculation are used to analyze these parameters. Alternatively, the rising use of 3-dimensional (3D) planification tools in arthroplasty requires the clarification if the 3D measurements are equivalent to 2D. The aim of this study was to compare B2 glenoids characteristics between 2D CT assessment method and 3D automated software method.

Methods

CT scans from patients who underwent a shoulder arthroplasty were identified. In the 2D method, measurement of glenoid version was determined. Measurement of the humeral head subluxation (HHS) (scapula axis method) was determined by the percentage of the humeral head posterior to the Friedman line (scapula axis). Three-dimensional analysis allowed an automated segmentation of the humerus and scapula, definition of scapular planes, and determination of glenoid version and HHS.

Results

Fifty-one CT scans met inclusion criteria. The intraobserver and interobserver reliability of the 2D retroversion (RV) and 2D HHS intraclass correlation coefficient was excellent (intraclass correlation coefficient>0.9).The median RV was 16° [12-20] in 2D and 19° [16-23] in 3D (P < .0001). The median subluxation was 71% [66-75] in 2D and 81% [78-86] in 3D (P < .0001). Linear regression analysis demonstrated low positive correlation between RV and subluxation in 2D and 3D (R² = 0.31 and R² = 0.23, respectively).

Discussion/Conclusion

The assessment of version and HHS in Walch B2 glenoids between 2D CT and a 3D planification were significantly different. Low correlation between RV and HHS was observed (2D and 3D assessment).