Preoperative planning for accurate glenoid component positioning in reverse shoulder arthroplasty

Use of computed tomography for shoulder arthroplasty: A systematic review

Introduction

The prevalence of total shoulder arthroplasties is on the rise annually. Improvements in implant quality, construct stability, and surgical techniques have notably enhanced post-operative results, prompting an expansion of indications for shoulder arthroplasty. Despite its high success rate, opportunities for enhancement remain, especially in preoperative planning and intraoperative execution. Advanced imaging technologies offer significant potential in optimizing implant placement, thus improving the longevity of the procedure. To our knowledge, a comprehensive review examining the impact of advanced imaging on shoulder arthroplasty has yet to be conducted. This systematic review aims to investigate the benefits of advanced imaging technologies in this context, focusing on their application in preoperative planning, osteoarthritis assessment, intraoperative adjustments, patient-specific instrumentation, and navigational aids.

Methods

This review utilized a comprehensive search of PubMed to identify relevant studies published from 2000 to 2024, focusing on the application of various imaging techniques in shoulder arthroplasty. The search was conducted by two authors and centered on plain radiography, CT scans, and MRI. The selection criteria included availability of full-text articles, English language, direct comparison of imaging techniques, and a focus on patient outcomes, including discussions on broader applications such as intraoperative navigation and patient-specific instrumentation development.

Results

Enhanced imaging techniques, particularly CT scans and MRIs, have been shown to significantly improve outcomes in shoulder arthroplasty. While plain radiographs remain standard, CT scans provide superior bony detail, crucial for evaluating glenoid wear and determining augmentation needs. Preoperative CT imaging has been demonstrated to enhance implant placement accuracy. Moreover, intraoperative technologies based on CT imaging, such as patient-specific instrumentation and navigation systems, contribute to better surgical results.

Conclusion

The benefits of CT imaging in shoulder arthroplasty significantly outweigh the associated costs. Current literature strongly supports the adoption of CT imaging in these procedures, particularly when used alongside modern operative technologies.

Intraoperative Navigation in Reverse Shoulder Arthroplasty: Advantages and Future Prospects

Intraoperative navigation is a novel technology that can provide real-time feedback to the surgeon during implantation and enhance the accuracy and precision of glenoid component positioning. Applications of intraoperative navigation systems have demonstrated increased precision in baseplate version and inclination, as well as improved baseplate screw placement, with fewer screws used and greater purchase length achieved when compared to standard instrumentation. Early clinical studies have shown favorable results, with significantly improved patient-reported and clinical outcomes and decreased complications. The implementation of intraoperative navigation is associated with a short learning curve and a minimal increase in operative time. Nevertheless, further research is necessary to substantiate the clinical benefit of navigation and evaluate its economic cost-effectiveness and impact on implant survival. Augmented reality and robotic-assisted surgery are additional emerging technologies that, while novel, hold the potential to further advance the field of shoulder arthroplasty.

Surgical management of biconcave glenoids: a scoping review

Biconcave (B2) glenoids, characterized by significant posterior glenoid bone loss and a biconcave wear pattern, are a challenging pathology in shoulder surgery. Significant bone defects present in B2 glenoids increases the risk of complications and rates of failure for operative patients with glenohumeral osteoarthritis. Diagnosing this entity is of pivotal importance, and can be accomplished with imaging and a comprehensive clinical investigation. There are no clear-cut guidelines for management, but options include hemiarthroplasty, anatomic total shoulder arthroplasty, and reverse shoulder arthroplasty. In recent years, modern techniques such as corrective reaming, bone grafts, and the use of augmented components have improved patient outcomes. Educating prospective patients is essential for reaching a shared management decision, setting appropriate expectations, and optimizing prognostic outcomes.

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.

Artificial Intelligence Machine Learning Algorithms Versus Standard Linear Demographic Analysis in Predicting Implant Size of Anatomic and Reverse Total Shoulder Arthroplasty

BACKGROUND

Accurate and precise templating is paramount for anatomic total shoulder arthroplasty (TSA) and reverse total shoulder arthroplasty (RSA) to enhance preoperative planning, streamline surgery, and improve implant positioning. We aimed to evaluate the predictive potential of readily available patient demographic data in TSA and RSA implant sizing, independent of implant design.

METHODS

A total of 578 consecutive, primary, noncemented shoulder arthroplasty cases were retrospectively reviewed. Demographic variables and implant characteristics were recorded. Multivariate linear regressions were conducted to predict implant sizes using patient demographic variables.

RESULTS

Linear models accurately predict TSA implant sizes within 2 millimeters of humerus stem sizes 75.3% of the time, head diameter 82.1%, head height 82.1%, and RSA glenosphere diameter 77.6% of the time. Linear models predict glenoid implant sizes accurately 68.2% and polyethylene thickness 76.6% of the time and within one size 100% and 95.7% of the time, respectively.

CONCLUSION

Linear models accurately predict shoulder arthroplasty implant sizes from demographic data. No significant statistical differences were observed between linear models and machine learning algorithms, although the analysis was underpowered. Future sufficiently powered studies are required for more robust assessment of machine learning models in predicting primary shoulder arthroplasty implant sizes based on patient demographics.

Experimental guide wire placement for total shoulder arthroplasty in glenoid models: higher precision for patient-specific aiming guides compared to standard technique without learning curve

BACKGROUND

Patient-specific aiming devices (PSAD) may improve precision and accuracy of glenoid component positioning in total shoulder arthroplasty, especially in degenerative glenoids. The aim of this study was to compare precision and accuracy of guide wire positioning into different glenoid models using a PSAD versus a standard guide.

METHODS

Three experienced shoulder surgeons inserted 2.5 mm K-wires into polyurethane cast glenoid models of type Walch A, B and C (in total 180 models). Every surgeon placed guide wires into 10 glenoids of each type with a standard guide by DePuy Synthes in group (I) and with a PSAD in group (II). Deviation from planned version, inclination and entry point was measured, as well as investigation of a possible learning curve.

RESULTS

Maximal deviation in version in B- and C-glenoids in (I) was 20.3° versus 4.8° in (II) (p < 0.001) and in inclination was 20.0° in (I) versus 3.7° in (II) (p < 0.001). For B-glenoid, more than 50% of the guide wires in (I) had a version deviation between 11.9° and 20.3° compared to ≤ 2.2° in (II) (p < 0.001). 50% of B- and C-glenoids in (I) showed a median inclination deviation of 4.6° (0.0°-20.0°; p < 0.001) versus 1.8° (0.0°-4.0°; p < 0.001) in (II). Deviation from the entry point was always less than 5.0 mm when using PSAD compared to a maximum of 7.7 mm with the standard guide and was most pronounced in type C (p < 0.001).

CONCLUSION

PSAD enhance precision and accuracy of guide wire placement particularly for deformed B and C type glenoids compared to a standard guide in vitro. There was no learning curve for PSAD. However, findings of this study cannot be directly translated to the clinical reality and require further corroboration.

Comparison of 3D computer-assisted planning with and without patient-specific instrumentation for severe bone defects in reverse total shoulder arthroplasty

BACKGROUND

Preoperative planning is an integral aspect of managing complex deformity in reverse shoulder arthroplasty (RSA). The purpose of this study was to compare the success of patient-specific instrumentation (PSI) and 3D computer-assisted planning with standard instrumentation (non-PSI) in achieving planned corrections of the glenoid among patients undergoing RSA with severe bony deformity requiring glenoid bone grafts.

METHODS

A retrospective case-control study was performed, including all patients that underwent RSA with combined bone grafting procedures (BIO-RSA or structural bone grafting) for severe glenoid deformity by a single study between June 2016 and July 2023. Patients were required to have preoperative and postoperative CT scans as well as preoperative 3D planning performed for inclusion. Patients were divided into two groups based on the use of 3D computer-assisted planning with or without PSI (PSI vs. non-PSI). The corrected inclination and version were measured by two separate reviewers on preoperative and postoperative 2D CT scans and compared to their corresponding preoperative planning goals utilizing bivariate analyses.

RESULTS

We identified 45 patients that met our inclusion criteria (22 PSI and 23 non-PSI). Preoperative inclination (mean ± SD) (PSI 10.12° ± 15.86°, non-PSI 9.43° ± 10.64°; P = .864) and version (PSI -18.78° ± 18.3°, non-PSI -17.82° ± 11.49°; P = .835) measurements were similar between groups. No significant differences in the mean deviation (error) between the postoperative and planned inclination (PSI 5.49° ± 3.72; non-PSI 6.91° ± 5.05; P = .437) and version (PSI 8.37° ± 5.7; non-PSI 5.37° ± 4.43; P = .054) were found between groups. No difference in the rate of outliers (>10° error) was noted in inclination (P = .135) or version (P = .445) between groups. Greater planned version correction was correlated with greater error when PSI was utilized (PSI r = 0.519, P = .013; non-PSI r = 0.362, P = .089).

CONCLUSION

Both PSI and 3D computer-assisted planning without PSI (non-PSI) appear to be useful techniques to achieve version and inclination correction among patients undergoing RSA with severe glenoid deformity required glenoid bone grafting with no clear superiority of one method over the other. Surgeons should be aware that when utilizing PSI, slightly greater error in achieving version goals may occur as version correction is increased.

[Reverse Shoulder Arthroplasty - Current Concepts]

Due to first promising long term outcome data, reverse shoulder arthroplasty experienced an immense increase of usage during the past decade. Moreover, the initial Grammont concept has constantly been refined and adapted to current scientific findings. Therefore, clinical and radiological problems like scapular notching and postoperative instability were constantly addressed but do still remain an area of concern.This article summarises current concepts in reverse shoulder arthroplasty and gives an overview of actual indications like cuff tear arthropathy, severe osteoarthritis, proximal humerus fractures, tumours, fracture sequelae as well as revision surgery and their corresponding clinical and radiological results.

The Value of Computed Tomography-Based Planning in Shoulder Arthroplasty Compared to Intra-/Interobserver Reliability of X-ray Planning

Background: Reversed total shoulder arthroplasty (RTSA) is an established surgery for many pathologies of the shoulder and the demand continues to rise with an aging population. Preoperative planning is mandatory to support the surgeon's understanding of the patient's individual anatomy and, therefore, is crucial for the patient's outcome. Methods: In this observational study, we identified 30 patients who underwent RTSA with two- and three-dimensional preoperative planning. Each patient underwent new two-dimensional planning from a medical student and an orthopedic resident as well as through a mid-volume and high-volume shoulder surgeon, which was repeated after a minimum of 4 weeks. The intra- and interobserver reliability was then analyzed and compared to the 3D planning and the implanted prosthesis. The evaluated parameters were the size of the pegged glenoid baseplate, glenosphere, and humeral short stem. Results: The inter-rater reliability showed higher deviations in all four raters compared to the 3D planning of the base plate, glenosphere, and shaft. The intra-rater reliability showed a better correlation in more experienced raters, especially in the planning of the shaft. Conclusions: Our study shows that 3D planning is more accurate than traditional planning on plain X-rays, despite experienced shoulder surgeons showing better results in 2D planning than inexperienced ones.

Effect of using a small baseplate on the radiological and clinical outcomes of reverse total shoulder arthroplasty in Asian patients

Aims

The aim of this study was to compare the clinical and radiological outcomes of reverse shoulder arthroplasty (RSA) using small and standard baseplates in Asian patients, and to investigate the impact of a mismatch in the sizes of the glenoid and the baseplate on the outcomes.

Methods

This was retrospective analysis of 50 and 33 RSAs using a standard (33.8 mm, ST group) and a small (29.5 mm, SM group) baseplate of the Equinoxe reverse shoulder system, which were undertaken between January 2017 and March 2021. Radiological evaluations included the size of the glenoid, the β-angle, the inclination of the glenoid component, inferior overhang, scapular notching, the location of the central cage in the baseplate within the vault and the mismatch in size between the glenoid and baseplate. Clinical evaluations included the range of motion (ROM) and functional scores. In subgroup analysis, comparisons were performed between those in whom the vault of the glenoid was perforated (VP group) and those in whom it was not perforated (VNP group).

Results

Perforation of the vault of the glenoid (p = 0.018) and size mismatch in height (p < 0.001) and width (p = 0.013) were significantly more frequent in the ST group than in the SM group. There was no significant difference in the clinical scores and ROM in the two groups, two years postoperatively (all p > 0.05). In subgroup analysis, the VP group had significantly less inferior overhang (p = 0.009), more scapular notching (p = 0.018), and more size mismatch in height (p < 0.001) and width (p = 0.025) than the VNP group.

Conclusion

In Asian patients with a small glenoid, using a 29.5 mm small baseplate at the time of RSA was more effective in reducing size mismatch between the glenoid and the baseplate, decreasing the incidence of perforation of the glenoid vault, and achieving optimal positioning of the baseplate compared with the use of a 33.8 mm standard baseplate. However, longer follow-up is required to assess the impact of these findings on the clinical outcomes.

Clinical and radiologic outcomes of Lima ProMade custom 3D-printed glenoid components in primary and revision reverse total shoulder arthroplasty with severe glenoid bone loss: a minimum 2-year follow-up

BACKGROUND

The purpose of this study is to report the clinical and radiologic outcomes of patients undergoing primary or revision reverse total shoulder arthroplasty using custom 3D-printed components to manage severe glenoid bone loss with a minimum of 2-year follow-up.

METHODS

Following ethical approval, patients were identified and invited to participate. Inclusion criteria were (1) severe glenoid bone loss necessitating the need for custom implants and (2) patients with definitive glenoid and humeral components implanted more than 2 years prior. Included patients underwent clinical assessment using the Oxford Shoulder Score (OSS), Constant-Murley score, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES), and the quick Disabilities of the Arm, Shoulder, and Hand questionnaire (QuickDASH). Radiographic assessment included anteroposterior and axial projections. Patients were invited to attend a computed tomography (CT) scan to confirm osseointegration. Statistical analysis used descriptive statistics (mean and standard deviation [SD]) and paired t test for parametric data.

RESULTS

Eleven patients declined to participate. Five patients were deceased prior to study commencement, leaving 42 remaining patients in this analysis. Three patients had revision surgery before the 2-year follow-up; of these, 2 retained their custom glenoid components. Mean follow-up was 31.6 months from surgery (range 24-52 months). All 4 scores improved: OSS from a mean 15 (SD 8.4) to 36 (SD 12) (P < .001), Constant-Murley score from a mean 15 (SD 11.2) to 52 (SD 20.1) (P < .001), QuickDASH from a mean 70 (SD 21) to 31 (SD 24.8) (P = .004), and the ASES score from a mean 22 (SD 17.8) to 71 (SD 23.3) (P = .007). Radiologic evaluation demonstrated good osseointegration in all but 1 included patient.

CONCLUSION

The utility of custom 3D-printed components for managing severe glenoid bone loss in primary and revision reverse total shoulder arthroplasty yields significant clinical improvements in this complex cohort. Large complex glenoid bone defects can be managed successfully with custom 3D-printed glenoid components.

The Value of Computer-Assisted Navigation for Glenoid Baseplate Implantation in Reverse Shoulder Arthroplasty: A Systematic Review and Meta-Analysis

BACKGROUND

Glenoid baseplate malpositioning during reverse total shoulder arthroplasty can contribute to perimeter impingement, dislocation, and loosening. Despite advances in preoperative planning, conventional instrumentation may lead to considerable inaccuracy in implant positioning unless patient-specific guides are used. Optical navigation has the potential to improve accuracy and precision when implanting a reverse shoulder arthroplasty baseplate. This systematic review aimed to analyze the most recent evidence on the accuracy and precision of glenoid baseplate positioning using intraoperative navigation and its potential impact on component selection and surgical time.

METHODS

We conducted a systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria. The PubMed, Scopus, and EMBASE databases were queried in July 2022 to identify all studies that compared navigation vs. conventional instrumentation for reverse shoulder arthroplasty. Data of deviation from the planned baseplate version and inclination, the use of standard or augmented glenoid components, and surgical time were extracted. Quantitative analysis from the included publications was performed using the inverse-variance approach and Mantel-Haenszel method.

RESULTS

Of the 2,048 records identified in the initial query, only 10 articles met the inclusion and exclusion criteria, comprising 667 shoulders that underwent reverse total shoulder arthroplasty. The pooled mean difference (MD) of the deviation from the planned baseplate position for the clinical studies was -0.44 (95% confidence interval [CI], -3.26; p = 0.76; I2 = 36%) for version and -8.75 (95% CI, -16.83 to -0.68; p = 0.02; I2 = 83%) for inclination, both in favor of navigation. The odds ratio of selecting an augmented glenoid component after preoperative planning and navigation-assisted surgery was 8.09 (95% CI, 3.82-17.14; p < 0.00001; I2 = 60%). The average surgical time was 12 minutes longer in the navigation group (MD 12.46, 95% CI, 5.20-19.72; p = 0.0008; I2 = 71%).

CONCLUSIONS

Preoperative planning integrated with computer-assisted navigation surgery seems to increase the accuracy and precision of glenoid baseplate inclination compared with the preoperatively planned placement during reverse total shoulder arthroplasty. The surgical time and proportion of augmented glenoid components significantly increase when using navigation. However, the clinical impact of these findings on improving prosthesis longevity, complications, and patient functional outcomes is still unknown.

LEVEL OF EVIDENCE

Level III, systematic review and meta-analysis. See Instructions for Authors for a complete description of levels of evidence.

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.

Emerging Technologies in Shoulder Arthroplasty: Navigation, Mixed Reality, and Preoperative Planning

Shoulder arthroplasty is a rapidly improving and utilized management for end-stage arthritis that is associated with improved functional outcomes, pain relief, and long-term implant survival. Accurate placement of the glenoid and humeral components is critical for improved outcomes. Traditionally, preoperative planning was limited to radiographs and 2-dimensional computed tomography (CT); however, 3-dimensional CT is becoming more commonly utilized and necessary to understand complex glenoid and humeral deformities. To further increase accurate component placement, intraoperative assistive devices-patient-specific instrumentation, navigation, and mixed reality-minimize malpositioning, increase surgeon accuracy, and maximize fixation. These intraoperative technologies likely represent the future of shoulder arthroplasty.

Accuracy of Blueprint software in predicting range of motion 1 year after reverse total shoulder arthroplasty

HYPOTHESIS AND BACKGROUND

Blueprint 3-dimensional computed tomography software has a functionality that predicts impingement-free range of motion (ROM) with determination of the limits of ROM at which bone and/or prosthetic impingement occurs. To our knowledge, only 1 previously published study has assessed the ability of Blueprint software to predict actual postoperative ROM after reverse total shoulder arthroplasty (RTSA). The hypotheses of this study were that (1) mean Blueprint-predicted impingement-free ROM would be statistically similar to the mean actual ROM 1 year after RTSA and (2) there would be a correlation between Blueprint-predicted impingement-free ROM and the actual ROM 1 year after RTSA.

MATERIALS AND METHODS

A retrospective review of patients who underwent Blueprint planning prior to undergoing RTSA from March 2017 through May 2021 was performed. At 1-year follow-up, flexion, external rotation at the side, abduction, external rotation in the abducted position, internal rotation in the abducted position, and internal rotation behind the back were measured. The preoperatively predicted flexion, extension, abduction, external rotation, and internal rotation were recorded using Blueprint software. The group 1 analysis examined the predicted vs. actual ROM of all 127 patients regardless of whether intraoperative component modifications were made. The group 2 analysis examined the predicted vs. actual ROM of only the patients who did not undergo intraoperative changes that would affect the preoperative ROM prediction (n = 97). The group 3 analysis examined the predicted vs. actual ROM of group 2 combined with the 30 patients who underwent post hoc Blueprint planning modifications to account for the changes made intraoperatively (combined sample size of 127).

RESULTS

Of the 141 patients, 127 (90%) were available for 1-year follow-up. When the mean values of all 3 groups were examined, the actual ROM and predicted ROM were statistically significantly different (P < .0001) for flexion, external rotation, abduction, abduction-external rotation, and abduction-internal rotation. In group 1, a very weak or poor correlation was found between predicted internal rotation and actual abducted internal rotation (r = 0.19, P = .04). For all other ROM metrics in groups 1, 2, and 3, there were no correlations between predicted and actual ROM (P ≥ .07).

CONCLUSIONS

In its current state, preoperative Blueprint 3-dimensional computed tomography planning software is unable to accurately predict ROM 1 year after RTSA.

Advanced 3D Visualization and 3D Printing in Radiology

Since the discovery of X-rays in 1895, medical imaging systems have played a crucial role in medicine by permitting the visualization of internal structures and understanding the function of organ systems. Traditional imaging modalities including Computed Tomography (CT), Magnetic Resonance Imaging (MRI) and Ultrasound (US) present fixed two-dimensional (2D) images which are difficult to conceptualize complex anatomy. Advanced volumetric medical imaging allows for three-dimensional (3D) image post-processing and image segmentation to be performed, enabling the creation of 3D volume renderings and enhanced visualization of pertinent anatomic structures in 3D. Furthermore, 3D imaging is used to generate 3D printed models and extended reality (augmented reality and virtual reality) models. A 3D image translates medical imaging information into a visual story rendering complex data and abstract ideas into an easily understood and tangible concept. Clinicians use 3D models to comprehend complex anatomical structures and to plan and guide surgical interventions more precisely. This chapter will review the volumetric radiological techniques that are commonly utilized for advanced 3D visualization. It will also provide examples of 3D printing and extended reality technology applications in radiology and describe the positive impact of advanced radiological image visualization on patient care.

Intraoperative and early postoperative complications of reverse shoulder arthroplasty: A current concepts review

Background

Reverse shoulder arthroplasty is a common procedure performed for a variety of shoulder pathologies.

Aims and objectives

This current concept review evaluates the intraoperative and early postoperative complications, with a specific focus given to neurological and vascular injury, fracture, dislocation and venous thromboembolism.

Conclusion

A detailed knowledge of potential complications will allow surgeons to mitigate risk and maximise outcomes.

The Reverse Shoulder Arthroplasty Angle in MRI: Impact of the Articular Cartilage in the Estimated Inclination of the Inferior Glenoid

Purpose

To describe the reverse shoulder arthroplasty angle (RSA angle) in magnetic resonance imaging (MRI) and compare the angle formed using bony landmarks (Bony RSA angle or B-RSA angle) with another angle formed using the cartilage margin as reference (Cartilage RSA angle or C-RSA angle).

Methods

Adult patients with a shoulder MRI obtained in our hospital between July 2020 and July 2021 were included. The C-RSA angle and B-RSA angle were measured. All images were independently assessed by 4 evaluators. Intraclass correlation coefficient (ICC) was determined for the B-RSA and C-RSA to evaluate interobserver agreement.

Results

A total of 61 patients were included with a median age of 59 years (17-77). C-RSA angle was significantly higher than B-RSA (25.4° ± 0.7 vs 19.5° ± 0.7, respectively) with a P-value <.001. The overall agreement was considered “good” for C-RSA (ICC = 0.74 [95% CI 0.61-0.83]) and “excellent” for B-RSA angle (ICC = 0.76 [95% CI 0.65-0.85]).

Conclusions

C-RSA angle is significantly higher than B-RSA angle. In cases without significant glenoid wear neglecting to account for the remaining articular cartilage at the inferior glenoid margin may result in superior inclination of standard surgical guides.

A Systematic Review of the Utility of Intraoperative Navigation During Total Shoulder Arthroplasty

Total shoulder arthroplasty (TSA) has been demonstrated to successfully recover function to shoulders impaired by arthrosis and rotator cuff insufficiency. Long-term survival depends on the correct positioning of glenoid components and secure bone fixation. Computed tomography (CT)-based intraoperative navigation has proven to be an effective technique for successful TSA procedures. This paper presents a review of CT-based intraoperative navigation considering its advantages and disadvantages. The crucial factors that contribute to the success of this technique are glenoid component positioning, operative duration, and screw selection, which are detailed in this review.

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°).

Description and Validation of the Anterior Glenoid Angle: A Novel MRI-Based Measure of Glenoid Morphologic Features and Version

The goal of this study was to establish a normal value for, and evaluate the reliability of, a new measurement of glenoid morphologic features using magnetic resonance imaging: the anterior glenoid angle. A total of 90 magnetic resonance imaging scans of patients without shoulder arthritis were reviewed. The anterior glenoid angle of each glenoid was measured by 4 blinded physicians. The images were randomized and measured again. Finally, the Friedman angle was measured on the same images for reference. Descriptive statistics and inter- and intraclass correlation coefficients were calculated. The mean anterior glenoid angle was 60.4°±3.6°. Of the measured values, 77% were between 56° and 64°. Intraobserver reliability was very good to excellent in single measure (range, 0.763-0.901) and mean measure (range, 0.865-0.948) comparisons. Interobserver reliability was very good to excellent in both single measure (0.769) and mean measure (0.964) comparisons. The mean Friedman angle was 10.2°. Correlation between the anterior glenoid angle and Friedman angle ranged from a moderate negative (-0.496) to a strong negative correlation (-0.711) among the observers. The mean anterior glenoid angle measured via magnetic resonance imaging scan was 60.4° in normal shoulders, and more than 75% of the values were within 4° of the mean. The anterior glenoid angle has excellent inter- and intrarater reliability without using computed tomography scan or including the entire scapula in the field of view. The anterior glenoid angle has a good to very good negative correlation with the Friedman angle because decreasing anterior glenoid angles indicate increasing retroversion. [Orthopedics. 2022;45(6):361-366.].

Navegação em cirurgia de artroplastia de ombro

The indication of shoulder arthroplasties has increased progressively. Accurate positioning of the components may have significant implications for clinical results. The navigation used to aid in the performance of anatomical and reverse total arthroplasties has provided greater precision in implant placement, especially on the glenoid. The development of the technique, material, and prosthesis design have shown encouraging results and led to a trend toward its expansion. In this way, we estimate a higher survival of the arthroplasties resulting from lower rates of dislocation and early loosening. We aim to describe the current technique and to present the results of the literature with navigation. However, comparative clinical studies with long term follow-up are necessary to prove the efficacy in the final results of total shoulder arthroplasties.

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.

Three dimensional patient-specific guides for guide pin positioning in reverse shoulder arthroplasty: An experimental study on different glenoid types

INTRODUCTION

Incorrect positioning is one of the main factors for glenoid component loosening in reverse shoulder arthroplasty and component placement can be challenging. This study aimed to assess whether Patient-Specific Instrumentation (PSI) provides better guide pin positioning accuracy and is superior to standard guided and freehand instrumentation methods in cases of glenoid bone deformity.

MATERIALS AND METHODS

Based on the Walch classification, five different scapula types were acquired by computed tomography (CT). For each type, two different surgeons placed a guide pin into the scapula using three different methods: freehand method, conventional non-patient-specific guide, and PSI guide. Each method was repeated five times by both surgeons. In these experiments, a total of 150 samples of scapula models were used (5 × 2 × 3 × 5 = 150). Post-operative CT scans of the samples with the guide pin were digitally assessed and the accuracy of the pin placement was determined by comparison to the preoperative planning on a three-dimensional (3D) model.

RESULTS

The PSI method showed accuracies to the preoperative plan of 2.68 (SD 2.10) degrees for version angle (p < .05), 2.59 (SD 2.68) degrees for inclination angle (p < .05), and 1.55 (SD 1.26) mm for entry point offset (p < .05). The mean and standard deviation errors compared to planned values of version angle, inclination angle, and entry point offset were statistically significant for the PSI method for the type C defected glenoid and non-arthritic glenoid.

CONCLUSION

Using the PSI guide created by an image processing software tool for guide pin positioning showed advantages in glenoid component positioning over other methods, for defected and intact glenoid types, but correlation with clinical outcomes should be examined.

An overview of 3D printing and the orthopaedic application of patient-specific models in malunion surgery

As the emerging technology of three-dimensional (3D) printing impacts several facets of medicine, innovative techniques and applications are increasingly being incorporated into clinical workflows. Specifically, 3D printing technology has allowed for the individualization of patient care through the creation of printed surgical guides, patient-specific anatomical models, and simulation practice models. In this paper, we review the broad applications of 3D printing in orthopaedic surgery. The purpose of this paper is to help orthopaedic trauma surgeons understand 3D printing's emerging influence on the delivery of care as well as how to directly apply this technology to their practice. We aim to illustrate these principles through a specific example of a patient who presented for malunion surgery. A 3D printed model of a very complex traumatic scapula malunion was used to not only pre-surgically plan the reconstruction, but to also facilitate provider and patient education. This paper highlights the benefits of 3D printing and how trauma surgeons are uniquely positioned to apply this technology to improve patient care.

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.

Patient-specific guides in orthopedic surgery

The interest of patient-specific guides (PSGs) lies in reliable intraoperative achievement of preoperative planning goals. They are a form of instrumentation optimizing intraoperative precision and thus improving the safety and reproducibility of surgical procedures. Clinical superiority, however, has not been demonstrated. The various steps from design to implementation leave room for error, which needs to be known and controlled by the surgeon who is responsible for final outcome. Instituting large-scale patient-specific surgery requires management systems for guides and innovative implants which cannot be a simple extension of current practices. We shall approach the present state of knowledge regarding PSGs via 5 questions: (1) What is a PSG? Single-use instrumentation produced after preoperative planning, aiming exclusively to optimize procedural exactness. (2) How to use and assess PSGs in orthopedic surgery? Strict rules of use must be adhered to. Any deviation from the predefined objective is, necessarily, an error that must be identified as such. (3) Do PSGs provide greater surgical exactness? The contribution of PSGs varies greatly between procedures. Exactness is enhanced in the spine, in osteotomies around the knee and in bone-tumor surgery. In the shoulder, their contribution is seen only in complex cases. Data are sparse for hip replacement, and controversial for knee replacement. (4) What are the expected benefits of PSGs? As well as improving exactness, PSGs allow a lower radiation dose and shorter operating time. They also enable junior surgeons to train in techniques otherwise reserved to hyperspecialists. (5) How to include PSGs in everyday practice? As well as their potential clinical interest, PSGs involve deep changes in organization, equipment provision and economic model. LEVEL OF EVIDENCE: V; expert opinion.

Patient-specific Instrumentation Versus Standard Surgical Instruments in Primary Reverse Total Shoulder Arthroplasty: A Retrospective Comparative Clinical Study

Aims

Patient-specific instrumentation (PSI) in primary shoulder arthroplasty has been studied; results supported the positive impact of the PSI on the glenoid positioning. Nevertheless, no clinical outcomes have been reported. We compare the clinical outcomes of primary reverse total shoulder arthroplasty using PSI versus the standard methods.

Methods

Fifty-three patients with full records and a minimum of 24-months follow-up were reviewed, 35 patients received primary standard RSTA, and 18 patients received primary PSI RSTA. All patients were operated on in a single center. The median follow-up was 46 months (53 months in the standard group vs 39 months in the PSI group).

Results

There was an overall significant post-operative improvement in the whole cohort (P< 0.05). The standard group had more deformed glenoids (B2, B3, C&D) and significantly low preoperative constant score and forward flexion (P=0.02 & 0.034). Compared to the PSI group (all were A1, A2, B1 &one type D), there were no statistically significant differences in any clinical outcome postoperatively. PSI neither prolonged the waiting time to surgery (P=0.693) nor the intraoperative time (P=0.962). Radiologically, PSI secured a higher percentage of optimum baseplate position and screw anchorage; however, no statistical correlation was found.

Conclusion

In this series, both groups achieved comparable good outcomes. PSI did not achieve significantly better clinical outcomes than Standard after primary RSTA. Yet comparison has some limitations. PSI did not negatively impact the waiting time or the surgical time.

CT versus MRI planning for reverse geometry total shoulder arthroplasty

Introduction

Preoperative planning for Reverse Total Shoulder Arthroplasty (RTSA) using CT or MRI is well described.1, 2, 3, 4, 5, 6, 7 We aimed to compare pre-operative CT versus MRI measurement accuracy for predicting intra-operative glenoid implant sizing.

Methods

All patients with a preoperative CT or MRI undergoing RTSA at our tertiary referral center from October 2017 to February 2020 were included. Data was collected from theatre and implant registers. Glenosphere Width (GW) and Baseplate Central Screw Length (BCSL) were independently predicted from pre-operative CT or MRI imaging by 2 blinded senior authors. A sub-group analysis was also performed between trauma and non-trauma CT cases. SPSS v26 was used for statistical comparison between predicted and actual implants.

Results

71 data sets from 69 patients were included for analysis: 31 CT predictions and 40 MRI predictions. 61.3% of CT measured GW predictions were accurate compared to 82.5% of MRI predictions (p = 0.045). BCSL predictions were 77.4% and 70% accurate for CT and MRI respectively, without significant difference. There was no significant difference in sub-group analysis for trauma vs elective CT accuracy of BCSL or GW measurements.

Conclusion

MRI imaging may be superior to CT for predicting GW and no less accurate than CT for predicting BCSL in the elective setting. No difference in CT measurement accuracy was seen between trauma and elective settings. While simultaneously clearly defining shoulder soft tissue anatomy, MRI may also be the preferred modality for bony measurements during pre-operative planning for elective RTSA.

Tomographic Analysis of Positioning of Reverse Baseplates Positioning

Objective

To verify whether reverse baseplate positioning without the support of intraoperative three-dimensional technology is within the acceptable parameters in the literature and whether glenoid bone deformity (GBD) compromises this positioning.

Methods

Sixty-nine reverse shoulder arthroplasties were evaluated with volumetric computed tomography (CT). Two radiologists performed blinded CT scan analysis and evaluated baseplate position within 2mm of the inferior glenoid; the inclination and version of the baseplate in relation to the Friedman line; and upper and lower screw and baseplate metallic peg end point positionings. The patients were divided according to the presence of GBD for statistical analyses.

Results

The two radiologists concurred reasonably in their interpretations of the following analyzed parameters: baseplate position within 2mm of the inferior glenoid rim (97.1% and 95.7%), baseplate inclination (82.6% and 81.2%), baseplate version (69.6% and 56.5%), the upper screw reaching the base of the coracoid process (71% and 79.7%), the inferior screw remaining inside the scapula (88.4% and 84.1%), and the metallic peg of the baseplate considered intraosseous (88.4% and 72.5%).

Conclusion

Reverse baseplate positioning without intraoperative three-dimensional technology is within the acceptable parameters of the literature, except for baseplate version and upper screw position. GBD did not interfere with baseplate positioning in reverse shoulder arthroplasty.

The Glenoid Vault Outer Cortex a new more accurate radiological reference for shoulder arthroplasty

Introduction: Correct positioning of the glenoid component is an important determinant of outcome in shoulder arthroplasty. We describe and assess a new radiological plane of reference for improving the accuracy of glenoid preparation prior to component implantation – the Glenoid Vault Outer Cortex (GvOC) plane. Methods: One hundred and five CT scans of normal scapulae were obtained. Forty six females and 59 males aged between 22 and 30 years. The accuracy of the GvOC plane was then compared against the current “gold standard” – the scapular border (SB). Measurements of glenoid inclination, version, rotation, and offset were obtained using both the GvOC and SB planes. These were then compared to actual values. Results: The mean difference between version obtained using the GvOC plane and the actual value was 1.8° (−2 to 5, SD 1.6) as compared to 6.7° (−2 to 17, SD 4.3) when the SB plane was used, (p < 0.001). The mean difference between estimates of inclination obtained using the GvOC plane and the actual were 1.9° (−4 to 6, SD 1.6) as compared to 11.2° (−4 to 25, SD 6.1) when the SB plane was used, (p < 0.001). Conclusions: The GvOC plane produced estimates of glenoid version and inclination closer to actual values with lower variance than when the SB plane was used. The GvOC may be a more accurate and reproducible radiological method for surgeons to use when defining glenoid anatomy prior to arthroplasty surgery.

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.

Impact of preoperative 3-dimensional planning and intraoperative navigation of shoulder arthroplasty on implant selection and operative time: a single surgeon's experience

BACKGROUND

Preoperative 3D planning and intraoperative navigation for shoulder arthroplasty has recently gained interest because of the potential to enhance the surgeon's understanding of glenoid anatomy and improve the accuracy of glenoid component positioning. The purpose of our study was to assess the impact of preoperative 3D planning on the surgeon's selection of the glenoid component (standard vs. augmented) and compare duration of surgery with and without intraoperative navigation.

METHODS

We retrospectively analyzed 200 consecutive patients who underwent shoulder arthroplasty. The first group of 100 patients underwent shoulder arthroplasty using standard 2D preoperative planning based on standard radiographs and computed tomographic scans. The second group of 100 patients underwent shoulder arthroplasty using 3D preoperative planning and intraoperative navigation. Type of glenoid component and operative time were recorded in each case.

RESULTS

For the group of patients with standard preoperative planning, only 15 augmented glenoid components were used, whereas in the group of patients with 3D preoperative planning and navigation, 54 augments were used (P < .001). The operative time was 11 minutes longer for the procedures that used intraoperative navigation, compared with those that did not (P < .001). This difference diminished as the surgeon became more proficient with the navigation technique.

CONCLUSION

Use of preoperative 3D planning changes the surgeon's understanding of the patient's glenoid anatomy. In our study, using 3D planning increased the likelihood that the surgeon selected an augmented glenoid component compared with 2D planning. Intraoperative navigation slightly lengthened the duration of surgery, but this became insignificant as part of a learning curve within 6 months.

Intersurgeon and intrasurgeon variability in preoperative planning of anatomic total shoulder arthroplasty: a quantitative comparison of 49 cases planned by 9 surgeons

BACKGROUND

Preoperative planning software is widely available for most anatomic total shoulder arthroplasty (ATSA) systems. It can be most useful in determining implant selection and placement with advanced glenoid wear. The purpose of this study was to quantify inter- and intrasurgeon variability in preoperative planning of a series of ATSA cases.

METHODS

Forty-nine computed tomography scans were planned for ATSA by 9 fellowship-trained shoulder surgeons using the ExactechGPS platform (Exactech Inc., Gainesville, FL, USA). Each case was planned a second time between 4 and 12 weeks later. Variability within and between surgeons was measured for implant type, size, version and inclination correction, and implant face position. Interclass correlation coefficients, Pearson, and Light's kappa coefficients were used for statistical analysis.

RESULTS

There was considerable variation in the frequency of augment use between surgeons and between rounds for the same surgeon. Thresholds for augment use also varied between surgeons. Interclass correlation coefficients for intersurgeon variability were 0.37 for version, 0.80 for inclination, 0.36 for implant type, and 0.36 for implant size. Pearson coefficients for intrasurgeon variability were 0.17 for version and 0.53 for inclination. Light's kappa coefficient for implant type was 0.64.

CONCLUSIONS

This study demonstrates substantial inter- and intrasurgeon variability in preoperative planning of ATSA. Although the magnitude of differences in correction was small, surgeons differed significantly in the use of augments to achieve the resultant plan. Surgeons differed from each other on thresholds for augment use and maximum allowable residual retroversion. This suggests that there may a range of acceptable corrections for each shoulder rather than a single optimal plan.

Intraoperative navigation and preoperative templating software are associated with increased glenoid baseplate screw length and use of augmented baseplates in reverse total shoulder arthroplasty

Background

Preoperative templating software and intraoperative navigation have the potential to impact baseplate augmentation utilization and increase screw length for baseplate fixation in reverse total shoulder arthroplasty (rTSA). We aimed to assess their impact on the (1) baseplate screw length, (2) number of screws used, and (3) frequency of augmented baseplate use in navigated rTSA.

Methods

We compared 51 patients who underwent navigated rTSA with 63 controls who underwent conventional rTSA at a single institution. Primary outcomes included the screw length, composite screw length, number of screws used, percentage of patients in whom 2 screws in total were used, and use of augmented baseplates.

Results

Navigation resulted in the use of significantly longer individual screws (36.7 mm vs. 30 mm, P < .0001), greater composite screw length (84 mm vs. 76 mm, P = .048), and fewer screws (2.5 ± 0.7 vs. 2.8 ± 1, P = .047), as well as an increased frequency of using 2 screws in total (35 of 51 patients [68.6%] vs. 32 of 63 controls [50.8%], P = .047). Preoperative templating resulted in more frequent augmented baseplate utilization (76.5% vs. 19.1%, P < .0001).

Conclusion

The difference in the screw length, number of screws used, and augmented baseplate use demonstrates the evolving role that computer navigation and preoperative templating play in surgical planning and the intraoperative technique for rTSA.

3D CT scan-based study of glenoid morphology in Indian population: Clinical relevance in design of reverse total shoulder arthroplasty

BACKGROUND

The knowledge of normal anatomy of glenoid in a population has relevance in terms of comparison with other regional and national population. Furthermore, it could enable clinicians to judge whether the available sizes of reverse total shoulder arthroplasty (RTSA) prosthesis could provide optimal fit for the glenoid in Indian patients.

METHODS

We evaluated consecutive 200 3-dimensional chest CT scans of 50 male and 50 female patients which included both shoulder joints and done for non-orthopaedic diseases at a tertiary care institute. The glenoid height, width, and version were measured using commercially available computer program.

RESULTS

Mean age of the patents was 38.6 ± 13.8 years (range, 19-59 years). The mean glenoid height was 33.9 ± 3.1 mm and maximum glenoid width was 24.2 ± 2.1 mm. Mean glenoid version in the study population was a retroversion of 3.47 ± 4.7°. The maximum glenoid width of 45% female and 15% male patients was less than 25 mm which is the diameter of smallest available glenoid baseplate among the commonly used RTSA systems.

CONCLUSIONS

The normal glenoid size of a large cohort of Indian population studied was smaller than that reported in cohorts from western countries. The glenoid width of substantial proportion of patients, especially female patients, was less than the diameter of smallest available glenoid baseplate. Clinical studies are needed in future in Indian patients undergoing RTSA to evaluate the glenoid bone-baseplate mismatch and ascertain the necessity of development of smaller size glenoid baseplate for optimal prosthesis fit in Indian patients.

Vault perforation after eccentric glenoid reaming for deformity correction in anatomic total shoulder arthroplasty

BACKGROUND

The management of glenoid deformity during anatomic total shoulder arthroplasty remains controversial. In this study, we evaluate variable correction of glenoid deformity by eccentric reaming. We hypothesize that partial correction of modified Walch B/C-type glenoid deformities can achieve 75% bone-implant contact area (BICA) with a reduced vault perforation risk compared with complete correction.

METHODS

Fifty shoulder computed tomographic scans with glenohumeral osteoarthritis were retrospectively evaluated. The Tornier BluePrint v2.1.5 software simulated 3 eccentric reaming scenarios including no, partial, and complete deformity correction. Each scenario was evaluated at 4 BICAs and using 3 implant fixation types. Three-dimensional surface representations were used to evaluate medialization and vault perforation.

RESULTS

The patients had mean glenoid retroversion and inclination of 18.5° and 8.8°, respectively, and mean posterior humeral head subluxation of 76%. With 75% BICA, the 3 fixation types had glenoid vault perforation in 6%-26% and 26%-54% of cases for partial and complete glenoid deformity correction, respectively. The central and posterior-inferior implant components were most likely to perforate across all scenarios.

DISCUSSION

Eccentric reaming for glenoid deformity correction increases the risk of vault perforation. Severe glenoid deformity required increased medialization to achieve 75% BICA. Pegged implants have increased chances of perforation compared with a keeled design; the central and posterior-inferior components were most likely to perforate during deformity correction.

CONCLUSION

Partial deformity correction of modified Walch B/C-type glenoid deformities can achieve 75% BICA while reducing the risk of vault perforation compared with complete correction at the time of anatomic total shoulder arthroplasty.

3D printing in shoulder surgery

Three-dimensional (3D) printing is a novel modality with the potential to make a huge impact in the surgical field. The aim of this paper is to provide an overview on the current use of 3D printing in shoulder surgery. We have reviewed the use of this new method in 3 fields of shoulder surgery: shoulder arthroplasty, recurrent shoulder instability and orthopedic shoulder traumatology. In shoulder arthroplasty, several authors have shown that the use of the 3D printer improves the positioning of the glenoid component, even if longer clinical follow-up is needed to determine whether the cost of this system rationalizes the potential improved functional outcomes and decreases glenoid revision rates. In the treatment of anterior shoulder instability, the literature agrees on the fact that the use of the 3D printing can: enhance the dept and size of bony lesions, allowing a patient tailored surgical planning and potentially reducing operative times; allow the production of personalized implants to restore substantial bone loss; restore glenohumeral morphology and instability. In orthopedic trauma, the use of 3D printing can be helpful to increase the understanding of fracture patterns, facilitating a more personalized planning, and can be used for resident training and education. We can conclude the current literature regarding the use of 3D printed models in orthopedic surgery agrees finding objective improvements to preoperative planning and to the surgical procedure itself, by shortening the intraoperative time and by the possibility to develop custom-made, patient-specific surgical instruments, and it suggests that there are tangible benefits for its implementation.

Reverse Total Shoulder Arthroplasty: Technique, Decision-Making and Exposure Tips

PURPOSE OF REVIEW

The goal of this review is to introduce surgical decision-making pearls for reverse shoulder arthroplasty and describe optimization of surgical exposure for reverse shoulder arthroplasty.

RECENT FINDINGS

While the technology of reverse shoulder replacement and the associated prosthetic options have expanded, the principles involved in successfully exposing the humerus and glenoid in arthroplasty remain the same. Reverse shoulder replacement should be considered in arthroplasty situations with rotator cuff disease, deformity, bone loss, and instability as part of the diagnosis. Optimal exposure in reverse shoulder arthroplasty can be obtained by (1) releasing deltoid adhesions, (2) removal of humeral osteophytes, (3) generous humeral head cuts, (4) thorough humeral and glenoid capsular release and (5) optimal glenoid retractor placement. Neuromuscular paralysis can also aid glenoid exposure.

Reverse Shoulder Arthroplasty for B2 Glenoid Deformity

In shoulder osteoarthritis, the B2 glenoid presents challenges in treatment because of the excessive retroversion and posterior deficiency of the glenoid. Correction of retroversion and maintenance of a stable joint line with well-fixed implants are essential for the successful treatment of this deformity with arthroplasty. Reverse shoulder arthroplasty offers several key advantages in achieving this goal, including favorable biomechanics, a well-fixed baseplate, and proven success in other applications. Techniques such as eccentric reaming, bone grafting, and baseplate augmentation allow surgeons to tailor treatment to the patient’s altered anatomy. Eccentric reaming is favored for correction of small defects or mild version anomalies. Current trends favor bone grafting for larger corrections, though augmented components have shown early promise with the potential for expanded use. With overall promising results reported in the literature, reverse shoulder arthroplasty is a useful tool for treating older patients with B2 glenoid deformities.

Reliability of a novel 3-dimensional computed tomography method for reverse shoulder arthroplasty postoperative evaluation

Background

Long-term function and survival of reverse shoulder arthroplasties (RSAs) are reliant on component positioning and fixation. Conventional postoperative analysis is performed using plain radiographs or 2-dimensional (2D) computed tomography (CT) images. Although 3-dimensional (3D) CT would be preferred, its use is limited by metal artifacts. This study proposes a new 3D CT method for postoperative RSA evaluation and compares its interobserver reliability with conventional methods.

Materials and methods

Preoperative and postoperative CT scans, as well as postoperative radiographs, were obtained from 18 patients who underwent RSA implantation; the scapula, implant, and screws were reconstructed as 3D CT models. The postoperative 3D scapula and implant were imported into preoperative coordinates and matched to the preoperative scapula. Standardized scapula coordinates were defined, in which the glenoid baseplate version and inclination angle were measured. The percentage of screw volume in bone was measured from a Boolean intersection operation between the preoperative scapula and screw models. Four independent reviewers performed the measurements using 3D CT and conventional 2D methods. Intraclass correlation coefficients (ICCs) were used to compare the reliability of the methods.

Results

The 3D CT method showed excellent reliability (ICC > 0.75) in baseplate inclination (ICC = 0.92), version (ICC = 0.97), and screw volume in bone (ICC = 0.99). Conventional 2D methods demonstrated poor reliability (ICC < 0.4). For radiographs, inclination showed poor reliability (ICC = 0.09) and the screw percentage in bone showed fair reliability (ICC = 0.54). Version was not measured with plain radiographs. For 2D CT slice measurements, inclination showed poor reliability (ICC = 0.02), version showed excellent reliability (ICC = 0.81), and the screw percentage in bone showed poor reliability (ICC = 0.28).

Conclusion

The new 3D CT-based method for evaluating RSA glenoid implant positioning and screw volume in bone showed excellent reliability and overcame the metal-artifact limitation of postoperative CT and 3D CT reconstruction.

Accuracy of patient-specific instrumentation in shoulder arthroplasty: a systematic review and meta-analysis

Background

There has been significant recent emphasis on the use of patient-specific instrumentation (PSI) in shoulder arthroplasty. However, clinical data are lacking to support the increased time and expense associated with PSI. Our purposes were to determine whether PSI significantly improves implantation accuracy during total shoulder arthroplasty (TSA) and to analyze available techniques and correlation with clinical outcomes. We hypothesized that PSI may improve glenoid component position radiographically but without correlation with clinical outcomes.

Methods

The MEDLINE, Scopus, Embase, and Cochrane Library databases were queried. Included articles reported use of any preoperative or intraoperative PSI techniques, models, or guides to assist with TSA prosthesis implantation. The primary outcomes were mean deviation from the preoperative plan in version (in degrees), inclination (in degrees), and entry-point offset on the glenoid (in millimeters).

Results

Among the included articles, 518 TSA procedures (352 anatomic and 166 reverse) were performed. The mean postoperative errors in both version and inclination angles were 5° or less in 20 articles (90.9%) using PSI. Meta-analysis revealed no statistically significant differences in version error (P > .999, I ² = 64.6%), inclination error (P = .702, I ² = 82.2%), or positional offset (P = .777, I ² = 85.7%) between PSI and standard instrumentation. No data regarding patient-reported outcome measures, range of motion, strength, or glenoid component loosening and longevity were reported.

Conclusions

Meta-analysis revealed no significant differences in accuracy between PSI and standard instrumentation. Although PSI may possess the potential to improve TSA techniques, further investigations regarding long-term clinical outcomes, impact on operating room time, and cost-effectiveness are warranted before PSI can be routinely recommended over conventional instrumentation.

Novel 3-dimensionally printed patient-specific guide improves accuracy compared with standard total shoulder arthroplasty guide: a cadaveric study

Background

Patient-specific instrumentation (PSI) systems for total shoulder arthroplasty (TSA) can improve glenoid component placement, but may involve considerable expense and production delays. The purpose of this study was to evaluate a novel technique for in-house production of 3-dimensionally printed, patient-specific glenoid guides. We hypothesized that our PSI guide would improve the accuracy of glenoid guide pin placement compared with a standard TSA guide.

Methods

We randomized 20 cadaveric shoulders to receive pin placement via the PSI guide (n = 10, study group) or standard TSA guide (n = 10, control group). PSI guides were designed to fit each glenoid based on 3-dimensional scapular models constructed from computed tomography scans. A presurgical plan was created for the guide pin trajectory in neutral version and inclination based on individual scapular anatomy. After pin placement, 3-dimensional models from repeated computed tomography scans were superimposed to calculate deviation from the presurgical plan for each specimen.

Results

Inclination deviation was significantly lower in the PSI group than in the standard guide group (1.5° ± 1.6° vs. 6.4° ± 5.0°, P = .009). The glenoid entry site exhibited significantly less deviation in the PSI group (0.8 ± 0.6 mm vs. 2.1 ± 1.2 mm, P = .008). The average production cost and time for the PSI guides were $29.95 and 4 hours 40 minutes per guide, respectively.

Conclusions

The PSI guide significantly improved the accuracy of glenoid pin placement compared with the standard TSA guide. Our PSI guides can be produced in-house, inexpensively, and with substantially reduced time compared with commercially available guides.

Three-dimensional measurement of glenoid dimensions and orientations

BACKGROUND

Asians generally have smaller stature than Europeans and Americans, and currently available implants used in reverse shoulder arthroplasty might not fit smaller bony anatomies. However, few articles have reported glenoid geometry in the Asian population. The purpose of this study was to measure the dimensions and orientations of the glenoid from three-dimensional computed tomography reconstructions of elderly Japanese subjects.

METHODS

This study included 100 shoulders (50 males and 50 females with >50 years of age). The mean age was 67 ± 7 years for both sexes, and the mean height was 167 ± 7 cm for males and 154 ± 6 cm for females. Three-dimensional scapular models were created from computed tomographic images, and the glenoid height, glenoid width, glenoid version, glenoid inclination, vault depth, and vault width were measured.

RESULTS

The mean glenoid height and width were 38.6 and 29.4 mm for males and 33.1 and 24.4 mm for females, respectively. Both retroversion and superior inclination were approximately 3° in both sexes. The glenoid vault was deeper in the posterior region with the maximum depth of 26.1 and 23.6 mm in males and females. The vault width was narrower in the anterior region with the anterior width of 2.5 mm at 15 mm medial from the glenoid face in females.

CONCLUSION

Glenoids of Japanese females are small compared to currently available baseplates for reverse shoulder arthroplasty. These results may be helpful to aid design in smaller baseplates that better fit the anatomic geometry of the Asian glenoid.

Thoughts on a new surgical assistance method for implanting the glenoid component during total shoulder arthroplasty. Part 1: Statistical modeling of the native premorbid glenoid

INTRODUCTION

The aim of this study was to identify points on the scapula that can be used to predict the anatomy of the native premorbid glenoid.

MATERIAL AND METHODS

Forty-three normal scapulas reconstructed in 3D and positioned in a common coordinate system were used. Twenty points distributed over the blade of the scapula (portion considered normal and used as a reference) and the glenoid (portion considered pathological and needing to be reconstructed) were captured manually. Thirteen distances (X) between two points not on the glenoid and 31 distances (Y) between two points of which at least one was on the glenoid were then calculated automatically. A multiple linear regression model was applied to calculate the Y distances from the X distances. The best four equations were retained based on their coefficient of determination (R²) to explain a point on the glenoid being reconstructed (p<0.05). In the first scenario, the glenoid was modeled assuming it was completely destroyed. In the second scenario, only the inferior portion of the glenoid was worn.

RESULTS

For a completely destroyed glenoid, the mean error for a chosen distance for a given point on the glenoid was 2.4 mm (4.e-3mm; 12.5mm). For a partially damaged glenoid, the mean error was 1.7mm (4.e-3mm; 6.5mm) for the same distance evaluated for a given point on the glenoid.

DISCUSSION/CONCLUSION

The proposed statistical model was used to predict the premorbid anatomy of the glenoid with an acceptable level of accuracy. A surgeon could use this information during the preoperative planning stage and during the actual surgery by using a new surgical assistance method.