The association between glenoid component design and revision risk in anatomic total shoulder arthroplasty

Bony integration of a hybrid glenoid component in anatomical shoulder arthroplasty : short-term CT scan analysis

Aims

Loosening of the glenoid component in the long term remains an important complication of the anatomical total shoulder arthroplasty (aTSA). The aim of this study was to explore the bony integration of a hybrid glenoid component based on an analysis of CT scans.

Methods

In a prospective multicentre study, patients who underwent primary aTSA, whose hybrid design of glenoid component included a fully-polyethylene flanged upper peg and a porous-coated titanium lower peg, and who were reviewed with CT scans between 12 and 24 months postoperatively, were included. Two independent observers reviewed the scans. Bony integration of the upper peg was scored as described by Arnold et al, and integration of the lower peg was scored as described by Gulotta et al. Perforation of the glenoid vault in any plane was also assessed.

Results

From an initial group of 120 aTSAs in 116 patients, 104 CT scans were analyzed in 100 patients (four bilateral shoulders, mean age 66 years (SD 11), 62 female and 38 male). Osteolysis around the upper peg was found in 32 patients (32 aTSAs; 31%). Of the remaining patients, 72 had a mean Arnold score of 5.6 points (SD 0.9), and 70 (67%) had perfect integration. The lower peg had a mean Gulotta score of 6.5 points (SD 1.4). There was perfect integration of the lower peg in 70 patients (70 aTSAs; 67%). A total of nine patients (nine aTSAs; 9%) had no bony integration at either peg. There was perforation of the glenoid in an anterior or posterior direction at the level of the upper peg in three and 28 patients, respectively. This occurred at the level of the lower peg in 11 and 18 patients, respectively. The inter- and intraobserver reliability was good (k = 0.782 and 0.86, respectively). No implant breakage occurred at a mean follow-up of 16 months (12 to 24). The clinical outcome was satisfactory at a mean follow-up of 32 months (24 to 35), as assessed by a visual analogue scale score for pain, the Constant-Murley score, Subjective Shoulder Value, and American Shoulder and Elbow Surgeons score.

Conclusion

Short-term CT scan analysis of a new hybrid anatomical glenoid component found perfect bony integration around the lower porous coated titanium peg in 90% of patients. The upper polyethylene flanged peg had bony integration in 70 patients (70 aTSAs; 67%). Longer follow-up is needed to analyze the rate of survival of this component. The short-term clinical outcome was satisfactory.

The Role of Inlay and Inset Glenoid Implants in Anatomic Total Shoulder Arthroplasty

Anatomic total shoulder arthroplasty is an established treatment for degenerative conditions involving the shoulder. One well-described complication of total shoulder arthroplasty is glenoid loosening, especially in younger and more active patients. As a result, several surgeons recommend against activities that may put patients at risk of implant failure after shoulder arthroplasty. Newer inlay and inset glenoid implants may have a role in treating arthritis in younger patients and may allow them to return to sports and high-impact activities, including weightlifting. These glenoid implants may also play a role in treating patients with notable glenoid deformity. However, more information is needed regarding their long-term outcomes.

A multicenter, randomized controlled trial comparing a second-generation uncemented trabecular metal-backed vs. cemented polyethylene glenoid component in total shoulder arthroplasty: 5-year results

BACKGROUND

Previously, we reported early (2-year) findings from a randomized controlled trial comparing a second-generation uncemented trabecular metal-backed (TM) glenoid vs. cemented polyethylene glenoid (POLY) in patients undergoing a total shoulder arthroplasty. The purpose of the current study is to report disease-specific quality of life, clinical, patient-reported, and radiographic outcomes at midterm (5-year) from this trial.

METHODS

Five surgeons from 3 centers participated. Patients 18-79 years with a primary diagnosis of glenohumeral osteoarthritis were screened for eligibility. Randomization to an uncemented TM or cemented POLY glenoid was performed intra-operatively after adequate bone stock was confirmed. Study intervals were baseline, 2- and 5-year postoperative. The primary outcome was the Western Ontario Osteoarthritis Shoulder (WOOS) quality of life score. Secondary outcomes included the American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form, EuroQol-5 Dimensions, and 12-Item Short Form Health Survey scores and clinical and radiographic examinations. Radiographic images were reviewed for metal debris according to Endrizzi. Mixed effects repeated measures analysis of variance for within- and between-group comparisons were performed.

RESULTS

Of the 104 patients who consented, 93 were randomized (46 TM; 47 POLY). There were no differences between groups at baseline (TM: mean age 66.5 years [standard deviation (SD) 6.4], 24 male and 22 female; and POLY: mean age 68.4 years [SD 5.5], 23 male / 24 female). Mean (SD) WOOS scores at baseline and 2 and 5 years were as follows: TM, 32 (21), 92 (13), and 93 (11); POLY, 27 (15), 93 (11), and 93 (10), respectively. No statistical or clinically relevant differences were noted with patient-reported outcomes between groups. Metal debris was observed in 11 (23.9%) patients, but outcomes were not negatively impacted, and debris severity was minor (grades 1 and 2). Complication rates were similar between groups (TM: 7 of 46 [15.2%], and POLY: 8 of 47 [17.0%]; P = .813). No aseptic glenoid failures were reported, but 1 patient in the TM group required revision because of infection.

CONCLUSIONS

Our short-term (2-year) findings were maintained with longer follow-up. At 5 years postoperation, there were no statistically or clinically significant differences between an uncemented second-generation TM glenoid and a cemented polyethylene glenoid with respect to disease-specific quality of life or patient-reported outcomes. No glenoid implant failures were reported, and complication rates were similar between groups. Only one complication was glenoid related (1 infection in the TM group). Metal debris was observed in 23.9% of patients with a TM glenoid but did not negatively influence implant survival, patient-reported outcomes, or shoulder function.

Primary Total Shoulder Arthroplasty is Superior to Hemiarthroplasty for the Treatment of Glenohumeral Arthritis: Analysis of 5-year Outcomes in a Large Surgical Database

Background

Total shoulder arthroplasty (TSA) is the preferred treatment for glenohumeral arthritis refractory to nonoperative measures. However, some surgeons have argued for a role for hemiarthroplasty (HA) in the setting of a smooth glenoid that articulates appropriately with the humeral head. The purpose of this study is to evaluate long-term revision rates and short-term postoperative complications in patients undergoing either HA or TSA for glenohumeral arthritis.

Methods

A retrospective review of patients who underwent HA and TSA was conducted using a commercially available national database. Demographics, postoperative complications, risk factors, revision rates, and costs were analyzed using 2 sample t-tests, chi-squared tests, and multivariate logistic regressions.

Results

Patients were stratified by operation: (1) HA (n = 1615) or 2) TSA (n = 7845). Patients undergoing primary TSA had higher rates of prior ipsilateral rotator cuff repair and corticosteroid injections. At 2 years, patients who underwent HA, 3.0% of patients had revision surgery, compared to 1.6% of patients who underwent TSA (P = .002); at 5 years, 3.7% of the HA cohort (P < .0001) had revision surgery, compared to 1.9% of patients who underwent TSA.

Conclusions

Patients undergoing TSA or RTSA for glenohumeral arthritis had higher preoperative co-morbidities but had no difference in short-term complication rates with a lower risk of revision surgery at both 2-year and 5-year follow-up when compared to HA. Increasing age, female sex, hyperlipidemia, postoperative infection, shoulder instability, and thromboembolism all independently increased odds for revision shoulder arthroplasty for glenohumeral arthritis.

Level of evidence Level

III.

Developing a machine learning algorithm to predict the probability of aseptic loosening of the glenoid component after anatomical total shoulder arthroplasty: protocol for a retrospective, multicentre study

INTRODUCTION

Despite technological advancements in recent years, glenoid component loosening remains a common complication after anatomical total shoulder arthroplasty (ATSA) and is one of the main causes of revision surgery. Increasing emphasis is placed on the prevention of glenoid component failure. Previous studies have successfully predicted range of motion, patient-reported outcomes and short-term complications after ATSA using machine learning methods, but an accurate predictive model for (glenoid component) revision is currently lacking. This study aims to use a large international database to accurately predict aseptic loosening of the glenoid component after ATSA using machine learning algorithms.

METHODS AND ANALYSIS

For this multicentre, retrospective study, individual patient data will be compiled from previously published studies reporting revision of ATSA. A systematic literature search will be performed in Medline (PubMed) identifying all studies reporting outcomes of ATSA. Authors will be contacted and invited to participate in the Machine Learning Consortium by sharing their anonymised databases. All databases reporting revisions after ATSA will be included, and individual patients with a follow-up less than 2 years or a fracture as the indication for ATSA will be excluded. First, features (predictive variables) will be identified using a random forest feature selection. The resulting features from the compiled database will be used to train various machine learning algorithms (stochastic gradient boosting, random forest, support vector machine, neural network and elastic-net penalised logistic regression). The developed and validated algorithms will be evaluated across discrimination (c-statistic), calibration, the Brier score and the decision curve analysis. The best-performing algorithm will be used to create an open-access online prediction tool.

ETHICS AND DISSEMINATION

Data will be collected adhering to the WHO regulation on data sharing. An Institutional Review Board review is not applicable. The study results will be published in a peer-reviewed journal.

Anatomic glenohumeral arthroplasty: State of the art

Anatomical total shoulder arthroplasty in its modern form where it reproduces the normal shoulder has been utilized clinically for more than half a century. As the technology and the designs have changed to recreate the humeral and glenoid sides of the joint, the sophistication of design has resulted in the growing number of cases annually worldwide. This increase is due in part to the increasing number of indications that the prosthesis can treat with successful results. On the humeral side, there have been design changes to better reflect the proximal humeral anatomy, and humeral stems are increasingly placed safely without cement. Platform systems which allow conversion of a failed arthroplasty to a reverse configuration without stem extraction is another design change. Similarly, there has been increasing utilization of short stem and stemless humeral components. Extensive experience with shorter stem and stemless devices, however, has yet to demonstrate the purported advantages of these devices, as recent studies have demonstrated equivalent blood loss, fracture rates, operative times, and outcome scores. Easier revision with these shorter stems remains to be definitively established, with only one study comparing the ease of revision between stem types. On the glenoid side, hybrid cementless glenoids, inlay glenoids, cementless all-polyethylene glenoids, and augmented glenoids have all been investigated; however, the indications for these devices remain unclear. Lastly, innovative surgical approaches to implanting shoulder arthroplasty and the use of patient specific guides and computerized planning, while interesting concepts, still await validation before they are utilized on a widespread basis. While reverse shoulder arthroplasty has been increasingly used to reconstruct the arthritic shoulder, anatomic glenohumeral replacement maintains a significant role in the armamentarium of the shoulder surgeon.

Use of Preoperative CT Scans and Patient-Specific Instrumentation May Not Improve Short-Term Adverse Events After Shoulder Arthroplasty: Results from a Large Integrated Health-Care System

Ongoing innovation leads to a continuous influx of new technologies related to shoulder arthroplasty. These are made available to surgeons and marketed to both health-care providers and patients with the hope of improving outcomes. We sought to evaluate how preoperative planning technologies for shoulder arthroplasty affect outcomes.

Methods

This was a retrospective cohort study conducted using data from an integrated health-care system's shoulder arthroplasty registry. Adult patients who underwent primary elective anatomic or reverse total shoulder arthroplasty (2015 to 2020) were identified. Preoperative planning technologies were identified as (1) a computed tomography (CT) scan and (2) patient-specific instrumentation (PSI). Multivariable Cox regression and logistic regression were used to compare the risk of aseptic revision and 90-day adverse events, respectively, between procedures for which technologies were and were not used.

Results

The study sample included 8,117 procedures (in 7,372 patients) with an average follow-up of 2.9 years (maximum, 6 years). No reduction in the risk of aseptic revision was observed for patients having either preoperative CT scans (hazard ratio [HR] = 1.22; 95% confidence interval [CI] = 0.87 to 1.72) or PSI (HR = 1.44; 95% CI = 0.71 to 2.92). Patients having CT scans had a lower likelihood of 90-day emergency department visits (odds ratio [OR] = 0.84; 95% CI = 0.73 to 0.97) but a higher likelihood of 90-day venous thromboembolic events (OR = 1.79; 95% CI = 1.18 to 2.74). Patients with PSI use had a higher likelihood of 90-day deep infection (OR = 7.74; 95% CI = 1.11 to 53.94).

Conclusions

We found no reduction in the risk of aseptic revision with the use of these technologies. Patients having CT scans and PSI use had a higher likelihood of venous thromboembolism and deep infection, respectively. Ongoing research with extended follow-up is being conducted to further examine the effects of these technologies on patient outcomes.

Level of Evidence

Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Comparing outcomes of central ingrowth peg vs. noningrowth pegged glenoid components during revision to reverse total shoulder arthroplasty

Background

One innovation to reduce glenoid loosening in total shoulder arthroplasty (TSA) is a large, central ingrowth peg. However, when bone ingrowth fails to occur, there is often increased bone loss surrounding the central peg which may increase complexity of subsequent revisions. Our goal was to compare outcomes between central ingrowth pegs and noningrowth pegged glenoid components during revision to reverse total shoulder arthroplasty.

Methods

In a comparative retrospective case series, all patients who underwent TSA-to-reverse TSA revision between 2014 and 2022 were reviewed. Demographic varibles as well as clinical and radiographic outcomes were collected. Ingrowth central peg and noningrowth pegged glenoid groups were compared using t-test, Mann-Whitney U, Chi-Square, or Fisher's exact tests where indicated.

Results

Overall, 49 patients were included: 27 underwent revision from noningrowth and 22 from central ingrowth components. Females more commonly had noningrowth components (74% vs. 45%, P = .04) and preoperative external rotation was higher in central ingrowth components (P = .02). Time to revision was significantly earlier in central ingrowth components (2.4 vs. 7.5 years, P = .01). Structural glenoid allografting was required more with noningrowth components (30% vs. 5%, P = .03) and time to revision in patients ultimately requiring allograft reconstruction was significantly later (9.96 vs. 3.68 years, P = .03).

Conclusion

Central ingrowth pegs on glenoid components were associated with decreased need for structural allograft reconstruction during revision; however, time to revision was earlier in these components. Further research should focus on whether glenoid failure is due to glenoid component design, time to revision, or both.

Average Indian Glenoid Sizes Are Smaller than All Commercially Available Glenoid Components: A Systematic Review

Background

Despite the variability in glenoid sizes geographically, most of the currently available commercial glenoid component designs are based on the glenoid parameters of the Caucasian population which may not be suitable for the Indian population due to a mismatch between the prosthesis and native anatomy. The aim of the present study is to systematically review the literature to determine the average glenoid anthropometric parameters in the Indian population.

Methods

A comprehensive literature search was conducted using preferred reporting items for systematic reviews and meta-analyses guidelines in the PubMed, EMBASE, Google Scholar, and Cochrane Library databases from the date of inception to May 2021. Any observational study conducted on the Indian population measuring the glenoid diameters, glenoid index, version, inclination, or any other glenoid measurements were included in the review.

Results

A total of 38 studies were included in this review. The glenoid parameters were assessed on intact cadaveric scapulae in 33 studies, on 3DCT in three studies, and 2DCT in one study. The pooled average of glenoid dimensions are as the following- the superoinferior diameter or height was 34.65 mm, anteroposterior1 diameter or maximum width was 23.72 mm, anteroposterior2 diameter or maximum width of the upper part of the glenoid was 17.05 mm, the glenoid index was 67.88, and the glenoid version was 1.75-degree retroversion. Males were having a mean height of 3.65 mm and maximum width of 2.74 mm larger than the females. A subgroup analysis revealed no significant difference between different parts of India in glenoid parameters.

Conclusion

The glenoid dimensions in the Indian population are smaller compared to the average European and American populations. The average glenoid maximum width of the Indian population is 1.3 mm smaller than the minimum glenoid baseplate size available in reverse shoulder arthroplasty. Glenoid components specific to the Indian market need to be designed to reduce glenoid failure attributable to the above findings.

Level of evidence

III.

Glenoid Prosthesis Design Considerations in Anatomic Total Shoulder Arthroplasty

Total shoulder arthroplasty is an increasingly popular option for the treatment of glenohumeral arthritis. Historically, the effectiveness of the procedure has largely been determined by the long-term stability of the glenoid component. Glenoid component loosening can lead to clinically concerning complications including pain with movement, loss of function, and accumulation of debris which may require surgery to revise. In response, there has been a push to optimize the design of the glenoid prosthesis. Traditional contemporary glenoid components use pegs for fixation and are made entirely of polyethylene. Variations on the standard implant include keeled, metal-backed, hybrid, augmented, and inlay designs. There is a wealth of biomechanical and clinical studies that report on the effectiveness of these different designs. The purpose of this review is to summarize existing literature regarding glenoid component design and identify key areas for future research. Knowledge of the rationale underlying glenoid design will help surgeons select the best component for their patients and optimize outcomes following TSA.

Short-term clinical and radiographic outcomes of a hybrid all-polyethylene glenoid based on preoperative glenoid morphology

BACKGROUND

The primary purpose of this study was to compare 2-year anatomic total shoulder arthroplasty (TSA) functional and radiographic outcomes between Walch type A and B glenoids treated with an all-polyethylene glenoid designed for hybrid fixation with peripheral cement and central osseous integration. The secondary purpose was to evaluate outcomes based on central peg technique. The hypotheses were that there would be no difference in short-term radiographic or functional outcome scores based on preoperative glenoid morphology or central peg technique.

METHODS

We performed a multicenter retrospective review of patients who underwent TSA with the same hybrid all-polyethylene glenoid and had minimum 2-year follow-up. Patient-reported outcomes and radiographic outcomes were analyzed based on preoperative Walch morphology and central peg technique. Radiographic analysis included preoperative glenoid morphology; preoperative and postoperative glenoid version, glenoid inclination, and posterior humeral head subluxation; and postoperative glenoid radiolucencies according to the Wirth and Lazarus classifications.

RESULTS

A total of 266 patients with a mean age of 64.9 ± 8.2 years were evaluated at a mean of 28 months postoperatively. Postoperatively, there were significant improvements in all functional outcome measures (P < .001), range-of-motion measures (forward elevation, external rotation at 0°, external rotation at 90°, internal rotation by spinal level, and internal rotation at 90°; P < .001), and strength measures (Constant, external rotation, and modified belly press; P < .001). There were no clinically meaningful differences in functional outcomes or statistically significant differences in radiographic appearance between Walch type A and B glenoids. Subgroup analysis revealed that glenoids with a cemented central peg had the worst radiographic outcomes based on Lazarus scoring.

CONCLUSION

Patients undergoing TSA with a hybrid in-line pegged glenoid have excellent clinical outcomes at short-term follow-up regardless of preoperative glenoid morphology. Different central peg techniques do not appear to play a significant role in the risk of glenoid component lucencies at 2 years postoperatively.

Comparison of Reverse and Anatomic Total Shoulder Arthroplasty in Patients With an Intact Rotator Cuff and No Previous Surgery

INTRODUCTION

This study's purpose is to compare clinical and radiographic outcomes of primary anatomic total shoulder arthroplasty (aTSA) and primary reverse total shoulder arthroplasty (rTSA) patients with osteoarthritis (OA) and an intact rotator cuff with no previous history of shoulder surgery using a single platform TSA system at a minimum follow-up of 2 years.

METHODS

A total of 370 aTSA patients and 370 rTSA patients matched for age, sex, and length of follow-up from an international multi-institutional Western Institutional Review Board approved registry with a minimum 2-year follow-up were reviewed for this study. All patients had a diagnosis of OA, an intact rotator cuff, and no previous shoulder surgery. All patients were evaluated and scored preoperatively and at latest follow-up using six outcome scoring metrics and four active range of motion measurements.

RESULTS

Mean follow-up was 41 months, and the mean age was 73 years. Preoperatively, the rTSA patients had lower outcome metrics and less motion. Postoperatively, aTSA and rTSA patients had similar clinical outcomes, motion, and function, with the only exception being greater external rotation in aTSA exceeding the minimal clinically important difference. Pain relief was excellent, and patient satisfaction was high in both groups. Humeral radiolucent lines were similar in both groups (8%). Complications were significantly higher with aTSA (aTSA = 4.9%; rTSA = 2.2%; P = 0.045), but revisions were similar (aTSA = 3.2%; rTSA = 1.4%; P = 0.086).

CONCLUSION

At a mean of 41 month follow-up, primary aTSA and rTSA patients with OA and an intact rotator cuff with no previous history of shoulder surgery had similar clinical and radiographic outcomes. Greater external rotation was noted in aTSA patients at follow-up. However, aTSA patients had a significantly greater rate of complications compared with rTSA patients. rTSA is a viable treatment option in patients with an intact rotator cuff and no previous shoulder surgery, offering similar clinical outcomes with a lower complication rate.

LEVEL OF EVIDENCE

Level III.

Mechanical behavior of hybrid glenoid components compared to all-PE components: a finite element analysis

Purpose

The purpose of this finite element study was to compare bone and cement stresses and implant micromotions among all-polyethylene (PE) and hybrid glenoid components. The hypothesis was that, compared to all-PE components, hybrid components yield lower bone and cement stresses with smaller micromotions.

Methods

Implant micromotions and cement and bone stresses were compared among 4 all PE (U-PG, U-KG, A-KG, I-KG) and 2 hybrid (E-hCG, I-hPG) virtually implanted glenoid components. Glenohumeral joint reaction forces were applied at five loading regions (central, anterior, posterior, superior and inferior). Implant failure was assumed if glenoid micromotion exceeded 75 µm or cement stresses exceeded 4 MPa. The critical cement volume (CCV) was based on the percentage of cement volume that exceeded 4 MPa. Results were pooled and summarized in boxplots, and differences evaluated using pairwise Wilcoxon Rank Sum tests.

Results

Differences in cement stress were found only between the I-hPG hybrid component (2.9 ± 1.0 MPa) and all-PE keeled-components (U-KG: 3.8 ± 0.9 MPa, p = 0.017; A-KG: 3.6 ± 0.5 MPa, p = 0.014; I-KG: 3.6 ± 0.6 MPa, p = 0.040). There were no differences in cortical and trabecular bone stresses among glenoid components. The E-hCG hybrid component exceeded micromotions of 75 µm in 2 patients. There were no differences in %CCV among glenoid components.

Conclusions

Finite element analyses reveal that compared to all-PE glenoid components, hybrid components yield similar average stresses within bone and cement. Finally, risk of fatigue failure of the cement mantle is equal for hybrid and all-PE components, as no difference in %CCV was observed.

Level of evidence

IV, in-silico.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40634-022-00494-8.

Survivorship of Anatomic Total Shoulder Arthroplasty

Anatomic total shoulder arthroplasty provides pain relief and improved quality of life for patients suffering from glenohumeral arthritis. The 10-year survival rate for these implants has been most recently reported at 96%. As the number of shoulder arthroplasties per year increases, it is important to evaluate factors associated with failure. Patient-specific variables such as age, sex, medical comorbidities, a history of previous shoulder surgery, and rotator cuff integrity can influence implant survival. Both surgeon and hospital volume have been shown to affect perioperative outcomes. Implant design and glenoid pathoanatomy are important structural considerations because both have a causal relationship with survivorship. Modifiable factors, such as smoking, body mass index, and alcohol or opioid consumption, should be addressed preoperatively when possible. Modifiable factors that pertain to surgery are equally as important; it is the responsibility of the surgeon to be aware of the reported outcomes for varying implants and technique-related pearls and pitfalls. For those perioperative factors that are nonmodifiable, it is prudent to counsel patients accordingly because these individuals may be more likely to require an eventual revision procedure.

Evaluation of clinical and radiographic outcomes after total shoulder arthroplasty with inset Trabecular Metal-backed glenoid

BACKGROUND

Trabecular Metal (TM)-backed glenoid implants were introduced for their theoretical ability to increase osseointegration while minimizing wear and the risk of loosening in total shoulder arthroplasty (TSA). Initial follow-up studies of TM-backed glenoids demonstrated high rates of metallic debris formation around the implant site, raising concerns about longevity. More recent data suggest that metallic debris formation may be less prevalent than previously reported and that the implants may have positive long-term outcomes regardless of debris. The goal of our study was to assess the clinical and radiographic outcomes at mid-term follow-up of TSA using a TM-backed glenoid implant placed with full backside support using an inset technique. We hypothesized that our clinical and radiographic outcomes would be good using this technique.

METHODS

We retrospectively reviewed the charts of 39 patients who underwent 41 TSA procedures with a Zimmer Biomet TM-backed glenoid component performed by a single surgeon between January 2010 and March 2016. After exclusions for death unrelated to surgery and loss to follow-up, 35 patients (37 shoulders) with minimum 2-year clinical follow-up were included in the study. The glenoids were all placed in an inset fashion with full backside support. Clinical, patient-reported, and radiographic outcomes were analyzed.

RESULTS

The average follow-up period was 7.2 years (range, 2-11 years). At final follow-up, average shoulder elevation was 153° ± 22° and average external rotation was 53° ± 12°. The average American Shoulder and Elbow Surgeons score was 86.8 ± 19.0, and the average visual analog scale score was 1.3 ± 2.4. Metallic debris was found in 9 shoulders (27%), and radiolucency was observed around the glenoid components in 13 shoulders (39%) on the final postoperative radiographs. Metallic debris and radiolucency findings were low in severity, with average grades of 0.32 (standard deviation, 0.54) and 0.39 (standard deviation, 0.50), respectively. There were no reoperations.

CONCLUSION

This study of 37 shoulders undergoing TSA with a TM-backed glenoid demonstrated 100% implant survivorship at an average follow-up of 7 years. Clinical outcomes were excellent despite the occurrence of some metallic debris formation. The findings suggest that a TM-backed glenoid component implanted in an inset fashion to achieve full backside support can provide good clinical and patient-reported outcomes in TSA patients at mid-term follow-up and suggest that continued consideration of the role of TM-backed glenoids and the optimal technique for implantation may be warranted.

Conversion of anatomic total shoulder arthroplasty to reverse shoulder arthroplasty using a unique hybrid glenoid component: technique and preliminary results

Background

Degenerative arthritis of the shoulder is a common condition that is successfully treated with anatomic total shoulder arthroplasty (TSA). Rotator cuff disease has evolved as a leading cause of failure of anatomic TSA, requiring revision to reverse shoulder arthroplasty (RSA). This revision procedure can be extremely complex, particularly if removal of a well-fixed glenoid component is necessary. This case series outlines the technique and preliminary clinical results of conversion of anatomic TSA to RSA utilizing both modular humeral and hybrid glenoid components.

Methods

From July 2017 to December 2019, the senior author (PMC) performed 84 consecutive anatomic TSA procedures utilizing a modular humeral arthroplasty system and a unique hybrid glenoid component. Three cases (3/84, or 3.6%) required conversion from anatomic TSA to RSA because of postoperative traumatic rotator cuff failure. All modular revision cases were performed without humeral stem removal and with utilization of the existing, well-fixed hybrid glenoid central titanium peg as the foundation for glenoid component revision. Preoperative and postoperative American Shoulder and Elbow Surgeons scores, visual analog scale pain scores, forward flexion, and patient satisfaction were analyzed in this modular revision group. In addition, several perioperative variables including operative time, blood loss, and length of stay were compared between this modular revision group and a nonmodular anatomic TSA to RSA revision comparative cohort.

Results

At an average follow-up of 24 months, average active forward flexion, postoperative American Shoulder and Elbow Surgeons scores, and visual analog scale pain scores improved significantly compared with preoperative scores in the modular revision group. All three patients were satisfied with their outcome. The average total operative time (109 minutes vs. 154 minutes, P = .02), blood loss (183 cc vs. 500 cc, P = .08), and length of hospital stay (26.3 hours vs. 36.6 hours P < .05) were lower in the modular revision group than those in a nonmodular revision cohort.

Conclusion

Revision of anatomic TSA to RSA utilizing a modular humeral system and a convertible hybrid glenoid component that does not require removal of a well-fixed central titanium peg which serves as the foundation for glenoid component revision was performed efficiently, safely, and successfully in three cases. This technique results in significantly improved clinical outcomes when revision to RSA is needed while potentially decreasing perioperative complications in the revision setting.

A Comparison of Revision Rates for Osteoarthritis of Primary Reverse Total Shoulder Arthroplasty to Primary Anatomic Shoulder Arthroplasty with a Cemented All-polyethylene Glenoid: Analysis from the Australian Orthopaedic Association National Joint Replacement Registry

BACKGROUND

There has been decreased use of anatomic total shoulder arthroplasty (aTSA) because reverse TSA (rTSA) is increasingly being used for the same indications. Although short-term studies generally have not found survivorship differences between these implant designs, these studies are often small and their follow-up is limited to the short term. Likewise, the degree to which patient characteristics (such as gender, age, and American Society of Anesthesiologists [ASA] score) may or may not be associated with survivorship differences calls for larger and longer-term studies than is often possible in single-center designs. Large national registry studies may be able to help answer these questions.

QUESTIONS/PURPOSES

By analyzing a large Australian registry series of primary aTSAs with cemented all-polyethylene glenoids and rTSA for osteoarthritis (OA), we asked: (1) Is the revision risk for OA higher for aTSA with all-polyethylene glenoids or for rTSA, adjusting for patient characteristics such as age, gender, ASA score, and BMI? (2) Is the patient's gender associated with differences in the revision risk after controlling for the potentially confounding factors of age, ASA score, and BMI?

METHODS

In this comparative, observational registry study performed between January 1, 2015, and December 31, 2019, all primary aTSAs with all-polyethylene glenoids and rTSA for OA as determined by the treating surgeon and reported to our national registry formed two groups for analysis. The study period was set to time-match for the collection of ASA score and BMI in 2012 and 2015, respectively. Our registry enrolls more than 97% of all shoulder arthroplasties undertaken in Australia. There were 29,294 primary shoulder arthroplasties; 1592 hemiarthroplasties, 1876 resurfacing and stemless shoulders, 269 stemmed, and 11,674 reverse shoulder arthroplasties were excluded for other diagnoses. A total of 1210 metal-backed glenoids in stemmed aTSA for OA were excluded. A total of 3795 primary aTSAs with all-polyethylene glenoids and 8878 primary rTSAs for OA were compared. An aTSA with an all-polyethylene glenoid and rTSA were more likely to be performed in women (56% and 61% of patients, respectively). The mean age was 69 ± 8 years for aTSA with all-polyethylene glenoids and 74 ± 8 years for rTSA. One aTSA for OA was performed in a patient with an unknown glenoid type. The ASA score (n = 12,438) and BMI (n = 11,233) were also recorded. The maximum follow-up was 5 years for both groups, and the mean follow-up was 2.6 ± 1.4 years for aTSA with all-polyethylene glenoids and 2.1 ± 1.4 years for rTSA. The endpoint was time to revision (all causes), and the cumulative percent revision was determined using Kaplan-Meier estimates of survivorship (time to revision) and HRs from Cox proportional hazard models that were adjusted for age, gender, ASA score, and BMI category.

RESULTS

Overall, there were no differences in the 4-year cumulative percent revision between the groups; the 4-year cumulative percent revision was 3.5% for aTSA with all-polyethylene glenoids (95% CI 2.9%-4.2%) and 3.0% for rTSA (95% CI 2.6%-3.5%). There was an increased risk of revision of rTSA compared with aTSA using all-polyethylene glenoids in the first 3 months (HR 2.17 [95% CI 1.25-3.70]; p = 0.006, adjusted for age, gender, ASA score, and BMI). After that time, there was no difference in the rate of revision, with the same adjustments. In the first 3 months, men undergoing rTSA had a higher rate of revision than men with aTSA using all-polyethylene glenoids (HR 4.0 [95% CI 1.72-9.09]; p = 0.001, adjusted for age, BMI, and ASA). There was no difference between men in the two groups after that time. Women with aTSA using all-polyethylene glenoids were at a greater risk of revision than women with rTSA from 3 months onward (HR 2.77 [95% CI 1.55-4.92]; p < 0.001, adjusted for age, BMI, and ASA), with no difference before that time.

CONCLUSION

Given the absence of survivorship differences at 4 years between rTSA and aTSA, but in light of the differences in the revision risk between men and women, surgeons might select an aTSA with an all-polyethylene glenoid to treat OA, despite the current popularity of rTSA. However, there are survivorship differences between genders. Future studies should evaluate whether our comparative findings are replicated in men and women undergoing aTSA with all-polyethylene glenoids and rTSA for primary diagnoses such as rheumatoid arthritis or post-traumatic arthritis, and whether there are functional differences between the two implant designs when used for OA.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Two-year results of a multi-centre, randomized controlled trial comparing a second-generation uncemented trabecular metal-backed versus cemented polyethylene glenoid component in total shoulder arthroplasty

Aims

To report early (two-year) postoperative findings from a randomized controlled trial (RCT) investigating disease-specific quality of life (QOL), clinical, patient-reported, and radiological outcomes in patients undergoing a total shoulder arthroplasty (TSA) with a second-generation uncemented trabecular metal (TM) glenoid versus a cemented polyethylene glenoid (POLY) component.

Methods

Five fellowship-trained surgeons from three centres participated. Patients aged between 18 and 79 years with a primary diagnosis of glenohumeral osteoarthritis were screened for eligibility. Patients were randomized intraoperatively to either a TM or POLY glenoid component. Study intervals were: baseline, six weeks, six-, 12-, and 24 months postoperatively. The primary outcome was the Western Ontario Osteoarthritis Shoulder QOL score. Radiological images were reviewed for metal debris. Mixed effects repeated measures analysis of variance for within and between group comparisons were performed.

Results

A total of 93 patients were randomized (46 TM; 47 POLY). No significant or clinically important differences were found with patient-reported outcomes at 24-month follow-up. Regarding the glenoid components, there were no complications or revision surgeries in either group. Grade 1 metal debris was observed in three (6.5%) patients with TM glenoids at 24 months but outcomes were not negatively impacted.

Conclusion

Early results from this RCT showed no differences in disease-specific QOL, radiographs, complication rates, or shoulder function between uncemented second-generation TM and cemented POLY glenoids at 24 months postoperatively. Revision surgeries and reoperations were reported in both groups, but none attributed to glenoid implant failure. At 24 months postoperatively, Grade 1 metal debris was found in 6.5% of patients with a TM glenoid but did not negatively influence patient-reported outcomes. Longer-term follow-up is needed and is underway.

Cite this article: Bone Jt Open 2021;2(9):728–736.

Glenoid Component Loosening in Anatomic Total Shoulder Arthroplasty: Association between Radiological Predictors and Clinical Parameters-An Observational Study

The mechanisms of glenoid component loosening in anatomic total shoulder arthroplasty (aTSA) are still unclear, and it remains undetermined which specific radiographic features are associated with clinical outcomes. Patients with primary osteoarthritis who underwent aTSA with a stemless implant and a pegged glenoid between January 2011 and December 2016 were extracted from a local registry. Anteroposterior radiographs were evaluated at six, 12, 24 months, and five years post-TSA for lateral humeral offset (LHO), joint gap (JG), acromiohumeral distance (AHD), and radiolucency (modified Franklin score); 147 patients were included. Mixed-model linear regression was used. Both constant score (CS) and subjective shoulder value (SSV) markedly decreased at five years follow-up compared to one year (p < 0.001 for both). AHD, LHO, and JG all showed a consistent and statistically significant decline over time, with the joint gap decreasing by half. Consistently, smaller JG and AHD were correlated with lower SSV (p = 0.03 and p = 0.07, respectively). Massive loosening was associated with a 14.5 points lower SSV (p < 0.01). Finally, narrowing of the JG was significantly correlated with increased radiolucency (p < 0.001) and tended toward worse SSV (p = 0.06). In summary, radiographic parameters displaying medialization and cranialization after aTSA with a cemented pegged glenoid are useful predictors of impaired shoulder function.

Is preoperative glenoid bone mineral density associated with aseptic glenoid implant loosening in anatomic total shoulder arthroplasty?

Background

Aseptic loosening of glenoid implants is the primary revision cause in anatomic total shoulder arthroplasty (aTSA). While supported by biomechanical studies, the impact of glenoid bone quality, more specifically bone mineral density (BMD), on aseptic glenoid loosening remains unclear. We hypothesized that lower preoperative glenoid BMD was associated with aseptic glenoid implant loosening in aTSA.

Methods

We retrospectively included 93 patients (69 females and 24 males; mean age, 69.2 years) who underwent preoperative non-arthrographic shoulder computed tomography (CT) scans and aTSA between 2002 and 2014. Preoperative glenoid BMD (CT numbers in Hounsfield unit) was measured in 3D using a reliable semi-automated quantitative method, in the following six contiguous volumes of interest (VOI): cortical, subchondral cortical plate (SC), subchondral trabecular, and three successive adjacent layers of trabecular bone. Univariate Cox regression was used to estimate the impact of preoperative glenoid BMD on aseptic glenoid implant loosening. We further compared 26 aseptic glenoid loosening patients with 56 matched control patients.

Results

Glenoid implant survival rates were 89% (95% confidence interval CI, 81–96%) and 57% (41–74%) at 5 and 10 years, respectively. Hazard ratios for the different glenoid VOIs ranged between 0.998 and 1.004 (95% CI [0.996, 1.007], p≥0.121). Only the SC VOI showed significantly lower CTn in the loosening group (622±104 HU) compared with the control group (658±88 HU) (p=0.048), though with a medium effect size (d=0.42). There were no significant differences in preoperative glenoid BMD in any other VOI between patients from the loosening and control groups.

Conclusions

Although the preoperative glenoid BMD was statistically significantly lower in the SC region of patients with aseptic glenoid implant loosening compared with controls, this single-VOI difference was only moderate. We are thus unable to prove that lower preoperative glenoid BMD is clearly associated with aseptic glenoid implant loosening in aTSA. However, due to its proven biomechanical role in glenoid implant survival, we recommend extending this study to larger CT datasets to further assess and better understand the impact of preoperative glenoid BMD on glenoid implant loosening/survival and aTSA outcome.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-020-03892-0.