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

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).

The Accuracy of Three-Dimensional CT Scan Software in Predicting Prosthetic Utilization in Total Shoulder Arthroplasty

INTRODUCTION

Recent innovations in shoulder arthroplasty include three-dimensional (3D) CT software imaging that can be used to predict which prosthetic implants will be used intraoperatively. Correct prediction of the implants may optimize supply chain logistics for the surgeon, hospital, ambulatory surgery center, and the implant company. The purpose of this study was to examine a single surgeon's experience with this software to determine its predictive accuracy in determining which implants would be used intraoperatively.

METHODS

A retrospective review of patients undergoing total shoulder arthroplasty (TSA) performed by a single surgeon was performed. Inclusion criteria were patients undergoing anatomic (aTSA) or reverse (rTSA) TSA examined preoperatively with the 3D CT planning software. A chart review was performed to compare the accuracy of the preoperative plan in predicting the actual prostheses implanted at surgery.

RESULTS

Two hundred seventy-eight shoulders from 260 patients were included. One hundred fifty-one shoulders underwent aTSA, and 127 shoulders underwent rTSA. The surgeon was able to predict the type of arthroplasty (anatomic versus reverse) implanted in 269 of 278 (97%) shoulders. Using the 3D CT software, the surgeon was able to predict all the implants implanted in 68 shoulders (24%). For aTSA, 3D CT imaging successfully predicted all implants implanted in 43 shoulders (28%), glenoid implants implanted in 120 of 148 shoulders (81%), and humeral implants implanted in 54 shoulders (36%). For rTSA, 3D CT imaging successfully predicted all implants implanted in 26 shoulders (20%), glenoid implants implanted in 106 shoulders (83%), and humeral implants implanted in 39 shoulders (31%).

CONCLUSIONS

The 3D CT software combined with surgeon's judgment provided a high accuracy (97%) in determining the type of arthroplasty, a moderately high accuracy in determining the glenoid implants (81% to 83%), a low accuracy in determining humeral implants (31% to 36%), and a low accuracy in determining all prostheses used for each surgery (20% to 28%).

LEVEL OF EVIDENCE

LOE IV-Diagnostic Case Series.

Identification of threshold pathoanatomic metrics in primary glenohumeral osteoarthritis

BACKGROUND

An assessment of the pathoanatomic parameters of the arthritic glenohumeral joint (GHJ) has the potential to identify discriminating metrics to differentiate glenoid types in shoulders with primary glenohumeral osteoarthritis (PGHOA). The aim was to identify the morphometric differences and threshold values between glenoid types including normal and arthritic glenoids with the various types in the Walch classification. We hypothesized that there would be clear morphometric discriminators between the various glenoid types and that specific numeric threshold values would allow identification of each glenoid type.

METHODS

The computed tomography scans of 707 shoulders were analyzed: 585 obtained from shoulders with PGHOA and 122 from shoulders without glenohumeral pathology. Glenoid morphology was classified according to the Walch classification. All computed tomography scans were imported in a dedicated automatic 3D-software program that referenced measurements to the scapular body plane. Glenoid and humeral modeling was performed using the best-fit sphere method, and the root-mean-square error was calculated. The direction and orientation of the glenoid and humerus described glenohumeral relationships.

RESULTS

Among shoulders with PGHOA, 90% of the glenoids and 85% of the humeral heads were directed posteriorly in reference to the scapular body plane. Several discriminatory pathoanatomic parameters were identified: GHJ narrowing < 3 mm was a discriminatory metric for type A glenoids. Posterior humeral subluxation > 70% discriminated type B1 from normal GHJs. The root-mean-square error was a discriminatory metric to distinguish type B2 from type A, type B3, and normal GHJs. Type B3 glenoids differed from type A2 by greater retroversion (>13°) and subluxation (>71%). The type C glenoid retroversion inferior limit was 21°, whereas normal glenoids never presented with retroversion > 16°.

CONCLUSION

Pathoanatomic metrics with the identified threshold values can be used to discriminate glenoid types in shoulders with PGHOA.

Computer-Assisted Preoperative Planning and Patient-Specific Instrumentation for Glenoid Implants in Shoulder Arthroplasty

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Glenoid component positioning affects implant survival after total shoulder arthroplasty, and accurate glenoid-component positioning is an important technical aspect.

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The use of virtual planning and patient-specific instrumentation has been shown to produce reliable implant placement in the laboratory and in some clinical studies.

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Currently available preoperative planning software programs employ different techniques to generate 3-dimensional models and produce anatomic measurements potentially affecting clinical decisions.

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There are no published data, to our knowledge, on the effect of preoperative computer planning and patient-specific instrumentation on long-term clinical outcomes.

Simulation in shoulder arthroplasty education using three-dimensional planning software: the role of guidelines and predicted range of motion

AIM

To demonstrate how reverse shoulder arthroplasty (RSA) planning software could be used to improve how the trainees position glenoid and humeral implants and obtain optimal simulated range of motion (ROM).

METHODS

We selected four groups of five various level participants: medical student (MS), junior resident (JR), senior resident (SR), and shoulder expert (SE). Thereafter, the 20 participants planned five cases of arthritic shoulders for a RSA on a validated planning software following three phases: (1) no guidelines and no ROM feedback, (2) guidelines but no ROM feedback, and (3) guidelines and ROM feedback. We evaluated the final simulated impingement-free ROM, the choice of the implant (baseplate size, graft, glenosphere), and the glenoid implant positioning.

RESULTS

MS planning were significantly improved by the ROM feedback only. JR took the best advantage of both guidelines and ROM in final results. SR planning were less performant than SE into phase 1 regarding flexion, external rotation, and adduction (respectively - 10°, p = 0.03; - 11°, p = 0.003; and - 3°, p = 0,03), but reached similar results into phase 3 (respectively - 2°, p = 0.329; - 4°, p = 0.44; - 2°, p = 0.319). For MS, JR, and SR, we observed a systematic improvement in the agreement over the study course. The glenoid diameter remained highly variable even for SE. Comparing glenoid implant position to SE, the distance error decreased with advancing phases.

CONCLUSION

Planning software can be used as a simulation training tool to improve implant positioning in shoulder arthroplasty procedures.

Variability in total shoulder arthroplasty planning software compared to a control CT-derived 3D printed scapula

BACKGROUND

Two techniques exist from which all 3D preoperative planning software for total shoulder arthroplasty are based. One technique is based on measurements constructed on the mid-glenoid and scapular landmarks (Landmark). The second is an automated system using a best-fit sphere technique (Automated). The purpose was to compare glenoid measurements from the two techniques against a control computed tomography-derived 3D printed scapula.

METHODS

Computed tomography scans of osteoarthritic shoulders of 20 patients undergoing primary total shoulder arthroplasty were analyzed with both 3D planning software techniques. Measurements from a 3D printed scapula (Scapula) from the true 3D computed tomography scan served as controls. Glenoid version and inclination measurements from each group were blinded and reviewed.

RESULTS

In 65% (Automated) and 45% (Landmark) of cases, either inclination or version varied by 5° or more versus 3D printed scapula. Significant variability in version differences compared to the scapula group existed (p = 0.007). Glenoid version from the Scapula = 13.0° ± 10.6°, Automated = 15.0° ± 13.9°, and Landmark = 12.2° ± 7.8°. Inclination from Scapula = 5.4° ± 7.9°, Automated = 6.1° ± 12.6°, and Landmark = 6.2° ± 9.1°.

DISCUSSION

A high percentage of cases showed discrepancies in glenoid inclination and version values from both techniques. Surgeons should be aware that regardless of software technique, there is variability compared to measurements from a control 3D computed tomography printed scapula.

Assessing the Value to the Patient of New Technologies in Anatomic Total Shoulder Arthroplasty

BACKGROUND

Publications regarding anatomic total shoulder arthroplasty (TSA) have consistently reported that they provide significant improvement for patients with glenohumeral arthritis. New TSA technologies that have been introduced with the goal of further improving these outcomes include preoperative computed tomography (CT) scans, 3-dimensional preoperative planning, patient-specific instrumentation, stemless and short-stemmed humeral components, as well as metal-backed, hybrid, and augmented glenoid components. The benefit of these new technologies in terms of patient-reported outcomes is unknown.

METHODS

We reviewed 114 articles presenting preoperative and postoperative values for commonly used patient-reported metrics. The results were analyzed to determine whether patient outcomes have improved over the 20 years during which new technologies became available.

RESULTS

The analysis did not identify evidence that the results of TSA were statistically or clinically improved over the 2 decades of study or that any of the individual technologies were associated with significant improvement in patient outcomes.

CONCLUSIONS

Additional research is required to document the clinical value of these new technologies to patients with glenohumeral arthritis.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Glenoid bony morphology of osteoarthritis prior to shoulder arthroplasty: what the surgeon wants to know and why

Shoulder arthroplasty is performed with increasing frequency, and osteoarthritis is the most common indication for this procedure. However, the glenoid side of the joint is widely recognized as a limiting factor in the long-term durability of shoulder replacement, and osteoarthritis leads to characteristic bony changes at the glenoid which can exacerbate this challenge by reducing the already limited glenoid bone stock, by altering biomechanics, and by interfering with operative exposure. This article reviews the Walch classification system for glenoid morphology. Several typical findings of osteoarthritis at the glenoid are discussed including central bone loss, posterior bone loss, retroversion, biconcavity, inclination, osteophyte formation, subchondral bone quality, and bone density. The three primary types of shoulder arthroplasty are reviewed, along with several techniques for addressing glenoid deformity, including eccentric reaming, bone grafting, and the use of augmented glenoid components. Ultimately, a primary objective at shoulder arthroplasty is to correct glenoid deformity while preserving bone stock, which depends critically on characterizing the glenoid at pre-operative imaging. Understanding the surgical techniques and the implications of glenoid morphology on surgical decision-making enables the radiologist to provide the morphologic information needed by the surgeon.

A novel method for localization of the maximum glenoid bone defect during reverse shoulder arthroplasty

Background

Management of glenoid bone defects during reverse shoulder arthroplasty remains a challenge. The aim of our study was to preoperatively localize the maximal depth of glenoid bone defects in relation to glenoid reaming.

Methods

Thirty preoperative shoulder computed tomography scans were collected. Three assessors created standardized surgical plans, using 3-dimensional (3D) computed tomography–based Blueprint planning software in which the reaming axis was held constant at zero degrees of version and inclination. Each plan resulted in a 2-dimensional (2D) image of the reamer’s contact on the glenoid and a corresponding 3D representation of the glenoid bone defect. The position of the maximum glenoid defect was localized on both the 2D and 3D images. Descriptive statistics were calculated. The correlation between angles from 2D and 3D images was assessed, and intraclass correlation was used to assess inter-rater and intrarater reliability.

Results

Twenty-eight patients were included. The overall mean difference between 2D and 3D angles was 5.4° (standard deviation 5.2°). The correlation between 2D and 3D angles was almost perfect. Intraclass correlation results demonstrated near-perfect agreement. The maximal glenoid defect was within 5% of a circle (or +/- 9°) from perpendicular to the high-side ream line in 85.1% of comparisons and was within 10% of a circle in 97.6% of comparisons.

Conclusion

Using Blueprint planning software, we have demonstrated with almost perfect agreement among 3 assessors that when the reaming axis is held constant, the maximum glenoid bone defect is reliably located perpendicular to the glenoid ream line.

Advanced Templating for Total Shoulder Arthroplasty

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Longitudinal clinical and radiographic success of total shoulder arthroplasty (TSA) is critically dependent on optimal glenoid component position.

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Historically, preoperative templating utilized radiographs with commercially produced overlay implant templates and a basic understanding of glenoid morphology.

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The advent of 3-dimensional imaging and templating has achieved more accurate and precise pathologic glenoid interrogation and glenoid implant positioning than historical 2-dimensional imaging.

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Advanced templating allows for the understanding of unique patient morphology, the recognition and anticipation of potential operative challenges, and the prediction of implant limitations, and it provides a method for preoperatively addressing abnormal glenoid morphology.

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Synergistic software, implants, and instrumentation have emerged with the aim of improving the accuracy of glenoid component implantation. Additional studies are warranted to determine the ultimate efficacy and cost-effectiveness of these technologies, as well as the potential for improvements in TSA outcomes.

Does commercially available shoulder arthroplasty preoperative planning software agree with surgeon measurements of version, inclination, and subluxation?

BACKGROUND

Preoperative planning with commercially available imaging software in shoulder arthroplasty may allow for improved decision-making and more accurate placement of the glenoid component.

METHODS

A total of 81 consecutive shoulder computed tomography scans obtained for preoperative planning purposes for shoulder arthroplasty were analyzed by commercially available software from 4 companies (Blueprint: Wright Medical, Memphis, TN, USA; GPS: Exactech, Gainesville, FL, USA; Materialise: DJO, Vista, CA, USA; and VIP: Arthrex, Naples, FL, USA) and by 5 fellowship-trained sports medicine/shoulder surgeons. Inclination, version, and subluxation of the humerus were measured in a blinded fashion on axial and coronal sequences at the mid-glenoid. Surgeon measurements were analyzed for agreement and were compared with the 4 commercial programs.

RESULTS

Surgeon reliability was acceptable for version (intraclass correlation coefficient [ICC]: 0.876), inclination (ICC: 0.84), and subluxation (ICC: 0.523). Significant differences were found between surgeon and commercial software measurements in version (P = .03), inclination (P = .023), and subluxation (P < .001). Software measurements tended to be more superiorly inclined (average -2° to 2° greater), more retroverted (average 2°-5° greater), and more posteriorly subluxed (average 7°-10° greater) than surgeon measurements. In comparing imaging software measurements, only Blueprint was found to produce significantly different version measurements than surgeon measurements (P = .02).

CONCLUSION

Preoperative planning software for shoulder arthroplasty has limited agreement in measures of version, inclination, and subluxation measurements, whereas surgeons have high inter-reliability. Surgeons should be cautious when using commercial software planning systems and when comparing publications that use different planning systems to determine preoperative glenoid deformity measurements.

Three Dimensional Anthropometric Analysis of Glenoid Anatomy in Normal Indian Population

BACKGROUND

Shoulder unlike any other joint has a wide range of mobility and is important in day to day activities. Different ethnic groups vary in skeletal anatomy and anthropometry. Most of our knowledge on the shoulder-anatomy, surgical technique and prosthesis designs is based on western literature. There are few studies on the Indian population. Our aim is to study the anthropometry of glenoid based on 3D CT scan of the shoulder. Our objectives are to calculate glenoid height, width, version, inclination, analyse the data for differences between male and female, compare data with similar studies in India and other countries and study the impact on shoulder arthroplasty implant size.

MATERIALS AND METHODS

100 CT scans (male/female-50/50) of the Indian population are studied from our database. Glenoid measurements are calculated and analyzed.

RESULTS

The mean value of glenoid height is 32.9 ± 3.2 mm (27.6-41.7 mm), width 23.4 ± 2.62 mm (19.1-30.9 mm), version 0.07 ± 5.38° (- 11° to + 10.85°) and inclination 6.68 ± 5.49° (- 9.91° to + 20.75°). In our study glenoid is retroverted, superiorly inclined and height is more than width. The height and width are less than French and Americans but slightly more than the Japanese population.

CONCLUSION

There are significant differences in Indian glenoid measurements compared to other countries. Even the smallest size of shoulder arthroplasty glenoid component currently available in India is larger than the mean glenoid size of our study. As shoulder replacement surgeries are rising in India, we may have to bring changes in the implant design and surgical technique to suit our population.

Three-dimensional geometry of the normal shoulder: a software analysis

BACKGROUND

Three-dimensional (3D) geometry of the normal glenohumeral bone anatomy and relations is poorly documented. Our aims were (1) to determine the 3D geometry of the normal glenohumeral joint (GHJ) with reference to the scapular body plane and (2) to identify spatial correlations between the orientation and direction of the humeral head and the glenoid.

METHODS

Computed tomographies (CTs) of the normal, noninjured GHJ were collected from patients who had undergone CTs in the setting of (1) polytrauma, (2) traumatic head injury, (3) chronic acromioclavicular joint dislocations, and (4) unilateral trauma with a contralateral normal shoulder. We performed 3D segmentation and measurements with a fully automatic software (Glenosys; Imascap). Measurements were made in reference to the scapular body plane and its transverse axis. Geometric measurements included version, inclination, direction, orientation, best-fit sphere radius (BFSR), humeral subluxation, critical shoulder angle, reverse shoulder angle, glenoid area, and glenohumeral distance. Statistical correlations were sought between glenoid and humeral 3D measurements (Pearson correlation).

RESULTS

A total of 122 normal GHJs (64 men, 58 women, age: 52 ± 17 years) were studied. The glenoid BFSR was always larger than the humerus BFSR (constant factor of 1.5, standard deviation = 0.2). The mean glenoid version and inclination were -6° ± 4° and 7° ± 5°, respectively. Men and women were found to have significantly different values for inclination (6° vs. 9°, P = .02), but not for version. Humeral subluxation was 59% ± 7%, with a linear correlation with glenoid retroversion (r = -0.70, P < .001) regardless of age. There was a significant and linear correlation between glenoid and humeral orientation and direction (r = 0.72 and r = 0.70, P < .001).

CONCLUSION

The 3D geometry of the glenoid and humeral head present distinct limits in normal shoulders that can be set as references in daily practice: version and inclination are -6° and 7°, respectively, and humeral posterior subluxation is 59%; interindividual variations, regardless of the size, are relative to the scapular plane. There exists a strong correlation between the position of the humeral head and the glenoid orientation and direction.

The Characteristics of the Favard E4 Glenoid Morphology in Cuff Tear Arthropathy: A CT Study

Background: Cuff tear arthropathy (CTA) is characterized by superior migration of the humeral head with superior erosion of the glenoid. Rarely, humeral head migration can be anteroinferior with associated anterior erosion of the glenoid, a pattern described by Favard as the type E4 glenoid. The purpose of this retrospective imaging study was to analyze the 2D and 3D characteristics of the E4 glenoid. Methods: A shoulder arthroplasty database of 258 cuff tear arthropathies was examined to identify patients with an E4 type deformity. This resulted in a study cohort of 15 females and 2 males with an average age of 75 years. All patients had radiographs and CT scans available for analysis. CT-scan DICOM (Digital Imaging and Communications in Medicine) data were uploaded to a validated three-dimensional (3D) imaging software. Muscle fatty infiltration, glenoid measurements (anteversion, inclination), and humeral head subluxation according to the scapular plane were determined. Results: The mean anteversion and inclination of the E4 cohort were 32° ± 14° and −5° ± 2, respectively. The mean anterior subluxation was 19% ± 16%. All cases had severe grade 3 or 4 fatty infiltration of the infraspinatus, whereas only 65% had grade 3 or 4 subscapularis fatty infiltration. A significant correlation existed between glenoid anteversion and humeral head subluxation (p < 0.001), but no correlation was found with muscle fatty infiltration. The CT analysis demonstrated an acquired erosive biconcave morphology in 11 patients (65%) and monoconcavity in 6 patients (35%). Conclusion: The E4 type glenoid deformity in cuff tear arthropathy is characterized by an anterior erosion and anteversion associated with anterior subluxation of the humeral head.

The implications of the glenoid angles and rotator cuff status in patients with osteoarthritis undergoing shoulder arthroplasty

BACKGROUND

The success of shoulder arthroplasty, both reverse and anatomical, depends on correcting the underlying glenoid deformity especially in patients with an osteoarthritis. We hypothesized that the distribution of glenoid version and especially inclination are underestimated in the shoulder arthritis population, and also that superior glenoid inclination can be detected through 3-dimensional (3D) software program of computed tomography (CT) to a greater proportion in patients with rotator cuff insufficiency, but also in patients with osteoarthritis with an intact rotator cuff. Because of the influence of rotator cuff imbalance on secondary glenoid wear the values of the critical shoulder angle (CSA) and the fatty infiltration of the rotator cuff are further analyzed. The aim of our study is to determine; 1) the distribution of glenoid inclination and version; 2) the relationship between glenoid inclination, version, the critical shoulder angle (CSA) to the status of the rotator cuff; 3) the proportion of patients with both an intact rotator cuff and a superior inclination greater than 10°.

METHODS

A total of 231 shoulders were evaluated with X-ray images, 3-dimentional (3D) software program of computed tomography (CT), and magnetic resonance imaging. The cohort was divided into 3 groups according to their inclination angles and also grouped as intact-rotator cuff and torn-cuff group.

RESULTS

The median (min/max) values for the 231 shoulders were 8° (- 23°/56°) for the inclination angle, - 11°(- 55°/23°) for the version angle, and 31.5°(17.6°/61.6°) for the CSA. The majority of the glenoids were found to show posterior-superior erosion. Glenoid inclination angle and CSA were significantly higher in torn-cuff group when compared with intact-cuff group (P < 0.001, both). The rotator cuff tears were statistically significant in high inclination group than low inclination group and no inclination group (p < 0.001). In the high inclination group, 41 of 105 (39%) shoulders had an intact rotator cuff, in about 18% of all shoulders.

CONCLUSION

Our findings show that 3D evaluation of glenoid inclination is mandatory for preoperative planning of shoulder replacement in order to properly assess superior inclination and that reverse shoulder arthroplasty may be considered more frequently than as previously expected, even when the rotator cuff is intact.

LEVEL OF EVIDENCE

Level III.

Is preoperative planning effective for intraoperative glenoid implant size and type selection during anatomic and reverse shoulder arthroplasty?

INTRODUCTION

Preoperative 3D planning programs for anatomic (TSA) and reverse total shoulder arthroplasty (RSA) allow the analysis of glenohumeral joint pathoanatomy and templating for implant size selection and placement. The aim of this multicenter study was to compare the preoperative glenoid implant type and size planned to the final glenoid implant type and size used intraoperatively.

METHODS

Two hundred patients (100 TSA and 100 RSA) with a mean age of 72 years who had undergone preoperative planning and subsequent shoulder arthroplasty (100 TSA and 100 RSA) were included. All preoperative plans were saved and were analyzed for arthroplasty type (TSA vs. RSA), implant type (augment vs. nonaugment), and size (ie, polyethylene size, polyethylene radius of curvature, glenoid baseplate diameter, baseplate post length, and baseplate lateralization). The preoperative plan was available during surgery and was compared to the final implants inserted by the surgeon.

RESULTS

There were no intraoperative conversions of TSA to RSA or vice versa. In patients planned for a TSA, complete concordance between the preoperative plan and final implant selection was 85%. A complete mismatch for TSA glenoid size, backside radius of curvature, and augmentation occurred in 2%. For RSA, complete concordance was found in 90% of cases. A complete mismatch for implant type, size, post length, and glenosphere size occurred in 3%.

CONCLUSION

A high concordance was found between preoperative 3D planning implant selection and the glenoid component inserted at surgery for TSA and RSA. This high concordance may assist with surgical preparedness, implant stocks, and possibly future implant production.

Templating in shoulder arthroplasty - A comparison of 2D CT to 3D CT planning software: A systematic review

BACKGROUND

Computed tomography (CT) utilizing computer software technology to generate three-dimensional (3D) rendering of the glenoid has become the preferred method for preoperative planning. It remains largely unknown what benefits this software may have to the intraoperative placement of the components and patient outcomes.

PURPOSE

The purpose of this systematic review is to compare 2D CT to 3D CT planning in total shoulder arthroplasty.

STUDY DESIGN

Systematic review.

METHODS

A systematic database search was conducted for relevant studies evaluating the role of 3D CT planning in total shoulder arthroplasty. The primary outcome was component placement variability, and the secondary outcomes were intra- and inter-observer reliability in the context of preoperative planning.

RESULTS

Following title-abstract and full-text screening, six eligible studies were included in the review (n = 237). The variability in glenoid measurements between 3D CT and 2D CT planning ranged from no significant difference to a 5° difference in version and 1.7° difference in inclination (p<0.05). Posterior bone loss was underestimated in 52% of the 2D measured patients relative to 3D CT groups. Irrespective of 2D and 3D planning (39% and 43% of cases respectively), surgeons elected to implant larger components than those templated. There was no literature identified comparing differences in time, cost, functional outcomes, complications, or patient satisfaction.

CONCLUSION

The paucity of evidence exploring clinical parameters makes it difficult to comment on clinical outcomes using different methods of templating. More studies are required to identify how improved radiographic outcomes translate into improvements that are clinically meaningful to patients.

Comparative study of glenoid version and inclination using two-dimensional images from computed tomography and three-dimensional reconstructed bone models

Background

This study was performed to compare glenoid version and inclination measured using two-dimensional (2D) images from computed tomography (CT) scans or three-dimensional (3D) reconstructed bone models.

Methods

Thirty patients who had undergone conventional CT scans were included. Two orthopedic surgeons measured glenoid version and inclination three times on 2D images from CT scans (2D measurement), and two other orthopedic surgeons performed the same measurements using 3D reconstructed bone models (3D measurement). The 3D-reconstructed bone models were acquired and measured with Mimics and 3-Matics (Materialise).

Results

Mean glenoid version and inclination in 2D measurements were -1.705º and 9.08º, respectively, while those in 3D measurements were 2.635º and 7.23º. The intra-observer reliability in 2D measurements was 0.605 and 0.698, respectively, while that in 3D measurements was 0.883 and 0.892. The inter-observer reliability in 2D measurements was 0.456 and 0.374, respectively, while that in 3D measurements was 0.853 and 0.845.

Conclusions

The difference between 2D and 3D measurements is not due to differences in image data but to the use of different tools. However, more consistent results were obtained in 3D measurement. Therefore, 3D measurement can be a good alternative for measuring glenoid version and inclination.

Preoperative glenoid considerations for shoulder arthroplasty: a review

Preoperative assessment of the glenoid in the setting of shoulder arthroplasty is critical to account for variations in glenoid morphology, wear, version, inclination, and glenohumeral subluxation.

Three-dimensional computed tomography (3D CT) scan assessment of the morphology of glenoid erosion allows for a more accurate surgical decision-making process to correct deformity and restore the joint line.

Newer technology has brought forth computer-assisted software for glenoid planning in shoulder arthroplasty and patient-specific instrumentation.

There have been promising early findings, although further evaluation is needed to determine how this technology impacts implant survivorship, function, and patient-reported outcomes.

Cite this article: EFORT Open Rev 2020;5:126-137. DOI: 10.1302/2058-5241.5.190011

Assessment of the Glenoid Morphology Based on Demographic Data in the Turkish Population

Purpose

In this study, our aim was to evaluate the glenoid version, height, and width measurements based on gender, side, age, height, and hand dominance in the Turkish population using computed tomography (CT) images.

Methods

In our study, CT images of 140 patients (62 females and 78 males; mean age: 39.6 years) who had no shoulder complaints were evaluated retrospectively. Glenoid version (GV), AP diameter (width), and SI diameter (height) on both shoulders were measured on the CT images. Correlations between patient gender, side, age, height, and hand dominance and the GV and size were evaluated.

Results

The right shoulder had a mean GV of −0.93 ± 7.80 degrees and the left shoulder had a GV of −0.88 ± 6.63 degrees (p > 0.05). The mean AP diameter of the glenoid was 26.57 ± 3.02 mm in the right shoulder and 26.33 ± 3.01 mm in the left shoulder (p > 0.05). The mean AP diameter of the glenoid was 26.57 ± 3.02 mm in the right shoulder and 26.33 ± 3.01 mm in the left shoulder (p > 0.05). The mean AP diameter of the glenoid was 26.57 ± 3.02 mm in the right shoulder and 26.33 ± 3.01 mm in the left shoulder (p > 0.05). The mean AP diameter of the glenoid was 26.57 ± 3.02 mm in the right shoulder and 26.33 ± 3.01 mm in the left shoulder (p > 0.05). The mean AP diameter of the glenoid was 26.57 ± 3.02 mm in the right shoulder and 26.33 ± 3.01 mm in the left shoulder (p > 0.05). The mean AP diameter of the glenoid was 26.57 ± 3.02 mm in the right shoulder and 26.33 ± 3.01 mm in the left shoulder (p > 0.05). The mean AP diameter of the glenoid was 26.57 ± 3.02 mm in the right shoulder and 26.33 ± 3.01 mm in the left shoulder (p > 0.05). The mean AP diameter of the glenoid was 26.57 ± 3.02 mm in the right shoulder and 26.33 ± 3.01 mm in the left shoulder (

Conclusion

Hand dominance had an effect on the glenoid version, while patient gender, age, and height had an effect on the glenoid size. The glenoid width in the Turkish population was similar to that of the European and American populations, and the glenoid height was similar to that of the Asian population. Our GV values were similar to those of the Asian population and more anteverted compared to the Western population. We believe that our findings will be useful in preoperative planning and in the production of implants for our population.

Automated three-dimensional measurements of version, inclination, and subluxation

BACKGROUND

Preoperative planning software has been developed to measure glenoid version, glenoid inclination, and humeral head subluxation on computed tomography (CT) for shoulder arthroplasty. However, most studies analyzing the effect of glenoid positioning on outcome were done prior to the introduction of planning software. Thus, measurements obtained from the software can only be extrapolated to predict failure provided they are similar to classic measurements. The purpose of this study was to compare measurements obtained using classic manual measuring techniques and measurements generated from automated image analysis software.

METHODS

Ninety-five two-dimensional computed tomography scans of shoulders with primary glenohumeral osteoarthritis were measured for version according to Friedman method, inclination according to Maurer method, and subluxation according to Walch method. DICOM files were loaded into an image analysis software (Blueprint, Wright Medical) and the output was compared with values obtained manually using a paired sample t-test.

RESULTS

Average manual measurements included 13.8° version, 13.2° inclination, and 56.2% subluxation. Average image analysis software values included 17.4° version (3.5° difference, p < 0.0001), 9.2° inclination (3.9° difference, p < 0.001), and 74.2% for subluxation (18% difference, p < 0.0001).

CONCLUSIONS

Glenoid version and inclination values from the software and manual measurement on two-dimensional computed tomography were relatively similar, within approximately 4°. However, subluxation measurements differed by approximately 20%.

Clinical relevance of augmented statistical shape model of the scapula in the glenoid region

OBJECTIVE

To illustrate (a) whether a statistical shape model (SSM) augmented with anatomical landmark set(s) performs better fitting and provides improved clinical relevance over non-augmented SSM and (b) which anatomical landmark set provides the best augmentation strategy for predicting the glenoid region of the scapula.

METHODS

Scapula SSM was built using 27 dry bone CT scans and augmented with three anatomical landmark sets (16 landmarks each) resulting in three augmented SSMs (aSSM_proposed, aSSM_set1, aSSM_set2). The non-augmented and three augmented SSMs were then used in a non-rigid registration (regression) algorithm to fit to six external scapular shapes. The prediction error by each type of SSM was evaluated in the glenoid region for the goodness of fit (mean error, root mean square error, Hausdorff distance and Dice similarity coefficient) and for four anatomical angles (critical shoulder angle, lateral acromion angle, glenoid inclination, glenopoar angle).

RESULTS

Inter- and intra-observer reliability for landmark selection was moderate to excellent (ICC>0.74). Prediction error was significantly lower for SSM_{non-augmented} for mean (0.9 mm) and root mean square (1.15 mm) distances. Dice coefficient was significantly higher (0.78) for aSSM_proposed compared to all other SSM types. Prediction error for anatomical angles was lowest using the aSSM_proposed for critical shoulder angle (3.4°), glenoid inclination (2.6°), and lateral acromion angle (3.2°).

CONCLUSION AND SIGNIFICANCE

The conventional SSM robustness criteria or better goodness of fit do not guarantee improved anatomical angle accuracy which may be crucial for certain clinical applications in pre-surgical planning. This study provides insights into how SSM augmented with region-specific anatomical landmarks can provide improved clinical relevance.

Pyrocarbon interposition shoulder arthroplasty in young arthritic patients: a prospective observational study

BACKGROUND

We evaluated survival and midterm results of pyrocarbon interposition shoulder arthroplasty (PISA) in arthritic patients younger than 65 years.

METHODS

Fifty-eight PISAs (InSpyre; Tornier-Wright, Bloomington, MN, USA), implanted in 56 patients between 2010 and 2015, were prospectively observed. The mean age at surgery was 52 ± 13 years. The cause was primary osteoarthritis (18), fracture sequelae (16), post-instability arthritis (15), aseptic necrosis (3), inflammatory disease (2), and failed hemiarthroplasty (4); 34 shoulders (61%) had previously undergone surgery. Glenoid erosion was assessed in 4 grades according to the Sperling classification. Humeral erosion was also assessed in 4 grades. Multivariate analysis was used to determine predisposing risk factors for both humeral and glenoid erosion.

RESULTS

At a mean follow-up of 47 ± 15 months, survival rate was 90%. Six patients (10%) required conversion to reverse total shoulder prosthesis for painful glenoid erosion (n = 2) and humeral erosion with greater tuberosity stress fractures (n = 4). The mean Constant score and subjective shoulder value significantly increased from 36 ± 14 points to 70 ± 15 points and 32% ± 14% to 75% ± 19%, respectively (P < .001). Humeral medialization was observed in 78% of the cases with increased pain score. Uncorrected anteroposterior implant subluxation (12 cases) was associated with lower Constant score (50 points vs. 72 points; P = .02) and lower subjective shoulder value (53% vs. 78%; P = .002). On multivariate analysis, no risk factors for glenoid or humeral erosion were found.

CONCLUSION

At midterm follow-up, PISA does not protect from progressive glenoid erosion and can lead to greater tuberosity erosion and stress fractures. Longer follow-up is required to see whether PISA survival will be superior to that of hemiarthroplasty.

Magnetic Resonance Imaging Correlates With Computed Tomography for Glenoid Version Calculation Despite Lack of Visibility of Medial Scapula

PURPOSE

To assess the accuracy of measuring glenoid version on magnetic resonance imaging (MRI) in the presence of varying amounts of the medial scapula body as compared with the gold standard of glenoid version measured on computed tomography (CT) imaging, including the entire scapula in a cohort of young patients with shoulder instability and without glenohumeral arthritis.

METHODS

A retrospective review was performed on instability patients with preoperative MRI and CT imaging. Measurements of available scapular width and glenoid version were performed using the Cobb angle method to measure the angle between the plane of the glenoid fossa to Friedman's line on axial images. Intra- and interrater reliability analysis was performed using intraclass correlation coefficients to assess agreement between MRI and CT measurements. Paired t tests were used to compare measurement differences between MRI and CT.

RESULTS

Thirty-two patients with both MRI and CT scans were assessed. Intra- and inter-rater assessment revealed strong agreement for scapular width measurement. For glenoid version measurement, intra-rater agreement was excellent and inter-rater agreement was moderate on CT and good on MRI. The mean available scapular body width was 24.7 mm longer on CT as compared with MRI (95% confidence interval 17.5-31.9, P < .0001; 109.8 ± 8.2 mm vs 85.1 ± 16.9 mm, respectively), with MRI having an average of 78.2% (±17.6%) of the CT scapular width shown on CT. No significant difference in glenoid version was found between MRI and CT (95% confidence interval -0.87 to 1.75, P = .499; MRI -2.57° vs CT -2.13°).

CONCLUSION

MRI provided significantly shorter available scapular widths when compared with CT imaging in a cohort of patients with glenohumeral instability and without arthritis. However, this failed to produce a significant difference of ≥5° in measured glenoid version compared with CT measurements when 75% (8 cm) of the scapular width was present on MRI. Measuring glenoid version on MRI does not appear to be significantly affected when the entirety of the medial border of the scapula is not included in the imaging field.

LEVEL OF EVIDENCE

Level III; study of diagnostic test.

The reverse shoulder arthroplasty angle: a new measurement of glenoid inclination for reverse shoulder arthroplasty

BACKGROUND

Avoiding superior inclination of the glenoid component in reverse shoulder arthroplasty (RSA) is crucial. We hypothesized that superior inclination was underestimated in RSA. Our purpose was to describe and assess a new measurement of inclination for the inferior portion of the glenoid (where the baseplate rests).

METHODS

The study included 47 shoulders with rotator cuff tear arthropathy (mean age, 76 years). The reverse shoulder arthroplasty angle (RSA angle), defined as the angle between the inferior part of the glenoid fossa and the perpendicular to the floor of the supraspinatus, was compared with the global glenoid inclination (β angle or total shoulder arthroplasty [TSA] angle). Measurements were made on plain anteroposterior radiographs and reformatted 2-dimensional (2D) computed tomography (CT) scans by 3 independent observers and compared with 3-dimensional (3D) software (Glenosys) measurements.

RESULTS

The mean RSA angle was 25° ± 8° on plain radiographs, 20° ± 6° on reformatted 2D CT scans, and 21° ± 5° via 3D reconstruction software. The mean TSA angle was on average 10° ± 5° lower than the mean RSA angle (P < .001); this difference was observed regardless of the method of measurement (radiographs, 2D CT, or 3D CT) and type of glenoid erosion according to Favard. In Favard type E1 glenoids with central concentric erosion, the difference between the 2 angles was 12° ± 4° (P < .001).

CONCLUSION

The same angle cannot be used to measure glenoid inclination in anatomic and reverse prostheses. The TSA (or β) angle underestimates the superior orientation of the reverse baseplate in RSA. The RSA angle (20° ± 5°) needs to be corrected to achieve neutral inclination of the baseplate (RSA angle = 0°). Surgeons should be aware that E1 glenoids (with central erosion) are at risk for baseplate superior tilt if the RSA angle is not corrected.

Influence of Radiographic Viewing Perspective on Glenoid Inclination Measurement

Introduction

The purposes of this study were to determine (1) whether glenoid inclination (GI) could be accurately measured on plain radiographs as compared to a gold-standard 3-dimensional (3D) measure and (2) whether GI could be reliably measured on plain radiographs.

Materials and Methods

Digitally reconstructed radiographs (DRRs) were made from 3D computed tomography reconstructions of 68 normal cadaver scapulae. DRRs were made in a variety of viewing angles. Inclination was measured on these DRRs. These measurements were also made using a gold-standard 3D method. Measurements were made by 2 orthopedic surgeons and 1 surgeon twice, to calculate interrater and intrarater intraclass correlation coefficients (ICCs).

Results

The gold-standard 3D β was 83 ± 5° (72°–98°). On neutral plain radiographs, the mean ± standard deviation 2D β angle was 80 ± 6° (range, 66°–99°). With regard to accuracy, the 2D β angle was significantly different from the 3D β angle, with the 2D β underestimating the 3D β by 5° (95% confidence intervals −1 to 12). With regard to reliability, interrater ICCs for 2D β with a neutral viewing angle was 0.79. Two-dimensional β varied widely with viewing angle from 0.24 to 0.88. Interrater ICCs for the 3D method was 0.83 (0.60–0.92). Intrarater ICCs for all 3 techniques were high (>0.91).

Conclusions

Two-dimensional radiographic GI measurement is not accurate, as it underestimates the 3D value by an average of 5° when compared to the gold-standard 3D measurement. GI 2D measurement reliability varies with viewing angle on plain radiographs and thus to accurately and reliably measure inclination 3D imaging is necessary.

Multilevel glenoid morphology and retroversion assessment in Walch B2 and B3 types

OBJECTIVE

A major factor that impacts the long-term outcome and complication rates of total shoulder arthroplasty is the preoperative posterior glenoid bone loss quantified by glenoid retroversion. The purpose of this study was to assess if glenoid retroversion varies significantly at different glenoid heights in Walch B2 and B3 glenoids.

MATERIALS AND METHODS

Patients with B2 and B3 glenoid types were included following retrospective review of 386 consecutive CT shoulder studies performed for arthroplasty preoperative planning. True axial CT reconstructions were created using a validated technique. Two readers independently measured the glenoid retroversion angles according to the Friedman method using the "intermediate" glenoid at three glenoid heights: 75% (upper), 50% (equator), and 25% (lower). The variances between the three levels for a given patient were calculated.

RESULTS

Twenty-nine B2 and 8 B3 glenoid types were included. There was no significant difference in variance of glenoid version among the three levels in B2 or B3 groups. The mean variance in retroversion degree between equator-lower, upper-equator, and upper-lower glenoid was - 0.4, 0.3, and - 0.2 for B2; and - 0.2, 1.9, and 1.9 for B3 glenoid, respectively. The level of inter-reader agreement was fair to good for variance at equator-lower, and good to excellent for upper-equator and upper-lower glenoid.

CONCLUSIONS

Glenoid version can be accurately measured at any level between 25 and 75% of glenoid height for Walch B2 and B3. We recommend that the glenoid equator be used as the reference to assure consistent and reliable version measurements in this group of patients.

Three-dimensional characterization of the anteverted glenoid (type D) in primary glenohumeral osteoarthritis

BACKGROUND

The Walch classification describes glenoid morphology in primary arthritis. As knowledge grows, several modifications to the classification have been proposed. The type D, a recent modification, was defined as an anteverted glenoid with or without anterior subluxation. Literature on the anteverted glenoid in primary osteoarthritis is limited. The purpose of this study, therefore, was to analyze the anatomic characteristics of the type D glenoid on radiographs and computed tomography (CT).

METHODS

The shoulder arthroplasty databases from 3 institutions were examined to identify patients with primary glenohumeral osteoarthritis and glenoid anteversion (≥5°), with or without anterior subluxation. The type D study cohort consisted of 18 patients (3% of the osteoarthritis cohort) and was a mean of 70 years old, with 11 women and 7 men. All radiographs were reviewed, and computed tomography Digital Imaging and Communications in Medicine (National Electrical Manufacturers Association, Rosslyn, VA, USA) data were analyzed on validated 3-dimensional imaging software. Rotator cuff fatty infiltration, glenoid measurements (anteversion and inclination), and humeral head subluxation according to the scapular plane were determined.

RESULTS

In the study cohort, the mean glenoid anteversion was 12° (range, 5°-24°), the mean inclination was 0°, and the mean anterior subluxation was 38% (range, 6%-56%). Eight patients (44%) had a biconcave glenoid with a posterosuperiorly positioned paleoglenoid and an anteroinferiorly positioned neoglenoid, and 10 patients had a monoconcave glenoid. Fatty infiltration of the rotator cuff muscles never exceeded Goutallier stage 2.

CONCLUSION

The type D glenoid is an addition to the original Walch classification and is characterized by glenoid anteversion (≥5°), anteroinferior humeral head subluxation, and absence of severe subscapularis fatty infiltration.

A Methodological Review of 3D Reconstruction Techniques in Tomographic Imaging

Computer Vision has provided immense support to medical diagnostics over the past two decades. Analogous to Non Destructive Testing of mechanical parts, advances in medical imaging has enabled surgeons to determine root cause of an illness by consulting medical images particularly 3-D imaging. 3-D modeling in medical imaging has been pursued using surface rendering, volume rendering and regularization based methods. Tomographic reconstruction in 3D is different from camera based scene reconstruction which has been achieved using various techniques including minimal surfaces, level sets, snakes, graph cuts, silhouettes, multi-scale approach, patchwork etc. In tomography limitations of image aquisition method i-e CT Scan, X Rays and MRI as well as non availability of camera parameters for calibration restrict the quality of final reconstruction. In this work, a comprehensive study of related approaches has been carried out with a view to provide a summary of state of the art 3D modeling algorithms developed over the past four decades and also to provide a foundation study for our future work which will include precise 3D reconstruction of human spine.