The glenoid in total shoulder arthroplasty

Recent Advances in the Design and Application of Shoulder Arthroplasty Implant Systems and Their Impact on Clinical Outcomes: A Comprehensive Review

Purpose of Review

This narrative review comprehensively aims to analyze recent advancements in shoulder arthroplasty, focusing on implant systems and their impact on patient outcomes. The purpose is to provide a nuanced understanding of the evolving landscape in shoulder arthroplasty, incorporating scientific, regulatory, and ethical dimensions.

Recent Findings

The review synthesizes recent literature on stemless implants, augmented glenoid components, inlay vs onlay configurations, convertible stems, and associated complications. Notable findings include improved patient-reported outcomes with stemless implants, variations in outcomes between inlay and onlay configurations, and the potential advantages of convertible stems. Additionally, the regulatory landscape, particularly the FDA's 510(k) pathway, is explored alongside ethical considerations, emphasizing the need for standardized international regulations.

Summary

Recent innovations in shoulder arthroplasty showcase promising advancements, with stemless implants demonstrating improved patient outcomes. The review underscores the necessity for ongoing research to address unresolved aspects and highlights the importance of a standardized regulatory framework to ensure patient safety globally. The synthesis of recent findings contributes to a comprehensive understanding of the current state of shoulder arthroplasty, guiding future research and clinical practices.

Clinical and Radiologic Outcomes after Anatomical Total Shoulder Replacement Using a Modular Metal-Backed Glenoid after a Mean Follow-Up of 5.7 Years

Background: Glenoid wear is a common complication of anatomical total shoulder arthroplasty (aTSA) with a metal-backed glenoid (MBG), and the clinical and radiological results of historical implants are poor. The aim of this work was to evaluate the clinical and radiological results of 25 participants as well as the longevity after implantation of an anatomic shoulder prosthesis with a recent, modular cementless flat metal-backed glenoid component after a mean follow-up of 5.7 years. Methods: Clinically, the Simple Shoulder Test (SST), UCLA Activity Score (UCLA), and Constant Murley Score (CMS) were evaluated. Radiographically, the radiolucent lines (RLs), humeral head migration (HHM), and lateral glenohumeral offset (LGHO) were assessed. Survival was calculated with Kaplan−Meier curves and life-table analysis. Results: The mean CMS at follow-up was 46.2 points (range: 14−77; SD: 19.5). In terms of the SST score, the average value was 6.5 points (range: 1−10; SD: 3.5). The UCLA activity score showed a mean value of 5.9 points (range: 1−9; SD: 2.1). There were 17 revisions after a mean follow-up of 68.2 months (range: 1.8−119.6; SD: 27.9). HHM occurred in every patient, with a mean measurement of 6.4 mm (range: 0.5−13.4; SD: 3.9; p < 0.0001). The mean LGHO between the initial postoperative and follow-up images was 2.6 mm (range: 0−4.0; SD: 1.5; p < 0.0001). RLs were found in 22 patients (88%) around the glenoid and in 21 patients (84%) around the humeral head prosthesis. Conclusion: The clinical and radiographic outcomes after metal-backed glenoids were poor at 2.2 to 8.4 years of follow-up. We determined devastating survival in the majority of cases (68%), with mostly inlay wear (71%) as the main reason that led to revision surgery. The use of metalback genoids cannot be recommended based on the data of this study.

Finite element analysis to predict short and medium-term performance of the anatomical Comprehensive® Total Shoulder System

BACKGROUND

The number of Total Shoulder Arthroplasties (TSA) has increased in these last years with significant increase of clinical success. However, glenoid component loosening remains the most common cause of failure.

OBJECTIVE

In this study we evaluated the critical conditions to predict short and medium-term performance of the uncemented anatomical Comprehensive® Total Shoulder System using a finite element model that was validated experimentally.

METHODS

The finite element models of an implanted shoulder analysed included total shoulder components with pegs. The models were simulated in 3 phases of adduction: 45°, 60° and 90° to determine the most critical situation. Two different bone-implant fixation conditions were considered: post-surgery and medium term (2 years).

RESULTS

These show that the critical condition is for the shoulder in 90° adduction were the highest contact stress (70 MPa) was observed in the glenoid component. Relatively to the interface implant-bone strains, the maximum (-16000 µε) was observed for the short-term in the lateral region of the humerus. The highest micromotions were observed in the central fixation post of the glenoid component, ranging from 20 to 25 µm, and 325 µm in the lateral plane of the humeral component.

CONCLUSION

The predicted results are in accordance with clinical studies published and micromotions of the humeral component can be used to predict loosening and to differentiate shoulder implant designs.

Return to Golf After Shoulder Arthroplasty: A Systematic Review

BACKGROUND

The number of golfers aged ≥65 years has increased in recent years, and shoulder arthritis is prevalent in this age group. Guidelines for return to golf (RTG) after shoulder arthroplasty have not been fully established.

PURPOSE

To review the data available in the current literature on RTG after shoulder arthroplasty.

STUDY DESIGN

Systematic review.

METHODS

A systematic review based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines was performed. Two independent reviewers searched PubMed, Embase, and the Cochrane Library using the terms "shoulder,""arthroplasty,""replacement," and "golf." The authors sought to include all studies investigating RTG after total shoulder arthroplasty (TSA), shoulder hemiarthroplasty (HA), and reverse shoulder arthroplasty (RSA). Outcomes of interest included indications for shoulder arthroplasty, surgical technique, rehabilitation protocol, amount of time between surgery and resumption of golf activity, and patient-reported outcome measures.

RESULTS

A total of 10 studies were included, 2 of which reported on golf performance after shoulder arthroplasty. The other 8 studies described return to sports after shoulder arthroplasty with golf-specific data for our analysis. Three studies that included patients who underwent TSA reported RTG rates ranging from 89% to 100% after mean follow-up periods of 5.1 to 8.4 months. Two studies included patients who underwent TSA and HA and reported RTG rates of 77% and 100% after mean intervals of 5.8 and 4.5 months, respectively. Two studies included patients who underwent RSA, with RTG rates of 50% and 79% after mean postoperative intervals of 5.3 and 6 months, respectively. One study included only patients undergoing HA, with an RTG rate of 54% and a mean RTG time of 6.5 months. Varying surgical procedures and baseline patient characteristics precluded our ability to draw conclusions regarding surgical technique, rehabilitation protocol, or patient-reported outcome measures among studies reporting these data.

CONCLUSION

Most patients who undergo a shoulder arthroplasty procedure can expect to resume playing golf approximately 6 months after the index procedure. The rate of return may be lower after RSA and HA as compared with anatomic TSA. The data presented in our review can help physicians counsel patients who wish to continue golf participation after a shoulder arthroplasty procedure.

Baseplate Options for Reverse Total Shoulder Arthroplasty

PURPOSE OF REVIEW

Baseplate fixation has been known to be the weak link in reverse total shoulder arthroplasty (RTSA). A wide variety of different baseplates options are currently available. This review investigates the recent literature to present the reader with an overview of the currently available baseplate options and modes of fixation.

RECENT FINDINGS

The main elements that differentiate baseplates are the central fixation element, the size of the baseplate, the shape, the backside geometry, whether or not an offset central fixation exists, the number of peripheral screws, and the availability of peripheral augmentation. The wide array of baseplate options indicates that no particular design has proven superiority. As such, surgeons should be aware of their options and choose an implant that the surgeon is comfortable with and one that best suits the individual patient anatomy. With the growing number of RTSA procedures and registries with long-term follow-up, future investigations will hopefully delineate the ideal baseplate design to optimize survivorship.

Difference in glenoid retroversion between two-dimensional axial computed tomography and three-dimensional reconstructed images

Background

The glenoid version of the shoulder joint correlates with the stability of the glenohumeral joint and the clinical results of total shoulder arthroplasty. We sought to analyze and compare the glenoid version measured by traditional axial two-dimensional (2D) computed tomography (CT) and three-dimensional (3D) reconstructed images at different levels.

Methods

A total of 30 cases, including 15 male and 15 female patients, who underwent 3D shoulder CT imaging was randomly selected and matched by sex consecutively at one hospital. The angular difference between the scapular body axis and 2D CT slice axis was measured. The glenoid version was assessed at three levels (midpoint, upper one-third, and center of the lower circle of the glenoid) using Friedman’s method in the axial plane with 2D CT images and at the same level of three different transverse planes using a 3D reconstructed image.

Results

The mean difference between the scapular body axis on the 3D reconstructed image and the 2D CT slice axis was 38.4°. At the level of the midpoint of the glenoid, the measurements were 1.7°±4.9° on the 2D CT images and −1.8°±4.1° in the 3D reconstructed image. At the level of the center of the lower circle, the measurements were 2.7°±5.2° on the 2D CT images and −0.5°±4.8° in the 3D reconstructed image. A statistically significant difference was found between the 2D CT and 3D reconstructed images at all three levels.

Conclusions

The glenoid version is measured differently between axial 2D CT and 3D reconstructed images at three levels. Use of 3D reconstructed imaging can provide a more accurate glenoid version profile relative to 2D CT. The glenoid version is measured differently at different levels.

Comparison of Clinical Outcomes After Anatomic Total Shoulder Arthroplasty and Reverse Shoulder Arthroplasty in Patients 70 Years and Older With Glenohumeral Osteoarthritis and an Intact Rotator Cuff

INTRODUCTION

As the indications for reverse shoulder arthroplasty (RSA) expand beyond traditional cuff tear arthropathy, the role of RSA in elderly patients with glenohumeral arthritis and an intact rotator cuff remains unclear.

METHODS

This retrospective cohort study included 135 patients who underwent RSA or total shoulder arthroplasty (TSA) at a single tertiary orthopedic center between 2005 and 2015 and were 70 years of age or older at the time of surgery. All patients had preoperative advanced imaging confirming an intact rotator cuff but active forward elevation less than 90°. Complications, reoperations, and patient survival were recorded from the medical record. Patient-reported outcomes (Pain visual analog scale, Satisfaction Score, American Shoulder and Elbow Surgeons [ASES], and Western Ontario Osteoarthritis of the Shoulder [WOOS]) and patient-reported range of motion were collected at a minimum of 2 years after procedure.

RESULTS

There was no significant difference in complication rate or revision surgery rate between patients undergoing TSA and RSA (complications 13.7% versus 12.1%, P = 0.810; reoperations 6.9% vs 3.0%, P = 0.418). There were no differences in patient-reported outcome measures between the two groups. Mean pain visual analog scale scores were low in both groups (0.72, SD 1.93 for TSA and 0.31, SD 0.72 for RSA). Satisfaction scores were high (86.1, SD 23.3 for TSA and 91.8, SD 9.0 for RSA, P = 0.286). Mean ASES and WOOS scores were also high in both groups (86 [SD 15.6] for TSA and 83 [SD 12.6] for RSA for ASES [P = 0.400] and 86 [SD 18.3] for TSA and 89 [SD 10.2] for RSA for WOOS [P = 0.400]). One hundred percent of subjects following RSA and 98% of subjects following TSA rated their forward elevation as full or nearly full (>135°) (P = 0.516).

DISCUSSION

Given the good clinical outcomes after both TSA and RSA, there may be an increased role for RSA in this elderly cohort to provide effective treatment of glenohumeral osteoarthritis.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

CT scan evaluation of glenoid bone and pectoralis major tendon: interest in shoulder prosthesis

Introduction: The shoulder arthroplasty brings satisfaction to patients in terms of quality of life and indolence. However whether anatomic implant or reverse, it does not escape from the loosening of the glenoid component. Moreover, optimal implantation is required to ensure the functional outcome without shortening of the arm. The purpose of this study is obtain CT scan evaluation of the glenoid bone stock in order to optimize glenoid component implantation and obtain a reference to determine optimal humeral component placement in case of humeral proximal fracture.

Materials and methods: Between 2010 and 2011 we have analyzed 200 intact shoulder’s CT. We measured maximal and minimal width in the transverse plane of the glenoid, the distance from the pectoralis major (PM) tendon to the humeral head, the greater tubercle, change of curvature and the anatomical neck.

Results: Mean maximum width was 27.4 ± 3.4 mm and mean minimum width was 15.5 ± 2.8 mm. Distances between upper edge of PM tendon to: humeral head, greater tubercle, change of curvature and anatomical neck were respectively: 67.6 ± 9.98 mm, 57.8 ± 10.3 mm, 28.7 ± 9 mm, and 34.2 ± 9.7 mm.

Conclusion: Our study has produced an assessment of glenoid bone stock for optimal positioning of the glenoid implant but also to obtain a reference to determine the ideal location of the humeral component in the case of proximal humerus fracture.

Porous metals and alternate bearing surfaces in shoulder arthroplasty

Total shoulder arthroplasty (TSA) provides an effective solution for the treatment of glenohumeral arthritis. However, long-term outcomes have been limited by glenoid component aseptic loosening and polyethylene (PE) wear. Previous attempts to improve glenoid fixation with metal-backed glenoids resulted in inferior results. Newer component designs that contain porous metal allow for biological ingrowth of the prosthesis, potentially improving longevity and overall outcomes. Porous metal can also improve humeral component fixation, obviating the need for cement and simplifying revision surgery. Advances such as highly cross-linked polyethylene (HXLPE), vitamin E-doped HXLPE, and alternate bearing surfaces like ceramics and pyrolytic carbon have proven to provide superior wear characteristics in other joint replacements and may prove beneficial in the shoulder as well.

Soft tissue balancing in total shoulder replacement

Total shoulder arthroplasty is now capable of recreating near anatomic reproduction of native bony shoulder anatomy, but the function and longevity of anatomic shoulder replacement is dependent on a competent soft tissue envelope and adequate motoring of all musculo-tendinous units about the shoulder. Balancing the soft tissues requires understanding of the anatomy and pathology, as well as technical skills. The advent of reverse shoulder biomechanics has brought with it special requirements of understanding of the soft tissue elements still left in the shoulder despite major rotator cuff deficiency.