Loosening and revision rates after total shoulder arthroplasty: a systematic review of cemented all-polyethylene glenoid and three modern designs of metal-backed glenoid

Short-term radiographic and clinical outcomes of patients treated with anatomic total shoulder arthroplasty using a modern-generation implant with a metal-backed glenoid component

BACKGROUND

A leading cause of anatomic total shoulder arthroplasty failure continues to be glenoid component loosening. Historically, metal-backed glenoids (MBGs) have shown decreased performance compared with polyethylene-backed glenoid (PEG) components. Previous studies have shown that MBG components have higher revision rates and shorter time to prosthetic failure compared with PEG components. However, the negative outcomes of many of these studies may have been linked to an examination of older generations of MBG implants, and do not account for newer technology. Thus, our study aims to assess the short-term radiographic and clinical outcomes of patients treated with anatomic total shoulder arthroplasty using the current and more modern generation of implants with a universal metal-backed glenoid component.

METHODS

We conducted a retrospective chart review of patients who had their primary anatomic shoulder replacement performed from 2017 to 2022 by a single surgeon, and used one of 2 currently available implants that incorporated a metal-backed glenoid component with a convertible baseplate. After the exclusion of those lost to follow-up, we included 26 patients in this study, 3 of whom underwent bilateral shoulder replacement surgery at staggered time intervals. The primary outcome measure was evidence of radiographic change via in-office X-ray reports. Analysis of radiographic changes was conducted for each postoperative visit, which was aimed for 2 weeks, 6 weeks, 12 weeks, 1 year, and annually thereafter. Secondary analysis tracked clinical progression and used Disabilities of the Arm, Shoulder, and Hand questionnaire (DASH) scores, range of motion evaluation, strength testing, and instability examination using evidence of apprehension and sulcus signs at each time interval.

RESULTS

In our study, radiographic changes at each time interval and the longest follow-up appointment demonstrated no evidence of hardware loosening of either the glenoid or the humeral component and no evidence of periprosthetic fracture or hardware failure of any kind for MBG implants. There were no revisions performed because of polyethylene wear. The overall average range of motion, strength, and DASH scores were improved at each postoperative visit.

CONCLUSION

Previous studies have suggested that TSA implants with MBG components may be inferior to PEG implants. However, the results of many of these studies may not be as representative of the current implant designs available today. Although additional studies are necessary to assess the long-term survivability of the implant and its effects on glenoid bone stock, our findings suggest that university MBG components have minimal complications, do not demonstrate loosening, and have acceptable outcomes in short-term follow-up.

Revision rate in metal compared to ceramic humeral head total shoulder arthroplasty and hemiarthroplasty

Aims

Metal and ceramic humeral head bearing surfaces are available choices in anatomical shoulder arthroplasties. Wear studies have shown superior performance of ceramic heads, however comparison of clinical outcomes according to bearing surface in total shoulder arthroplasty (TSA) and hemiarthroplasty (HA) is limited. This study aimed to compare the rates of revision and reoperation following metal and ceramic humeral head TSA and HA using data from the National Joint Registry (NJR), which collects data from England, Wales, Northern Ireland, Isle of Man and the States of Guernsey.

Methods

NJR shoulder arthroplasty records were linked to Hospital Episode Statistics and the National Mortality Register. TSA and HA performed for osteoarthritis (OA) in patients with an intact rotator cuff were included. Metal and ceramic humeral head prostheses were matched within separate TSA and HA groups using propensity scores based on 12 and 11 characteristics, respectively. The primary outcome was time to first revision and the secondary outcome was non-revision reoperation.

Results

A total of 4,799 TSAs (3,578 metal, 1,221 ceramic) and 1,363 HAs (1,020 metal, 343 ceramic) were included. The rate of revision was higher for metal compared with ceramic TSA, hazard ratio (HR) 3.31 (95% confidence interval (CI) 1.67 to 6.58). At eight years, prosthesis survival for ceramic TSA was 98.7% (95% CI 97.3 to 99.4) compared with 96.4% (95% CI 95.2 to 97.3) for metal TSA. The majority of revision TSAs were for cuff insufficiency or instability/dislocation. There was no significant difference in the revision rate for ceramic compared with metal head HA (HR 1.33 (95% CI 0.76 to 2.34)). For ceramic HA, eight-year prosthetic survival was 92.8% (95% CI 86.9 to 96.1), compared with 91.6% (95% CI 89.3 to 93.5) for metal HA. The majority of revision HAs were for cuff failure.

Conclusion

The rate of all-cause revision was higher following metal compared with ceramic humeral head TSA in patients with OA and an intact rotator cuff. There was no difference in the revision rate for HA according to bearing surface.

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.

Stemless reverse humeral component neck-shaft angle has an influence on initial fixation

BACKGROUND

Stemless anatomic humeral components are commonly used and are an accepted alternative to traditional stemmed implants in patients with good bone quality. Presently, little literature exists on the design and implantation parameters that influence primary time-zero fixation of stemless reverse humeral implants. Accordingly, this finite element analysis study assessed the surgical implantation variable of neck-shaft angle, and its effect on the primary time-zero fixation of reversed stemless humeral implants.

METHODS

Eight computed tomography-derived humeral finite element models were used to examine a generic stemless humeral implant at varying neck-shaft angles of 130°, 135°, 140°, 145°, and 150°. Four loading scenarios (30° shoulder abduction with neutral forearm rotation, 30° shoulder abduction with forearm supination, a head-height lifting motion, and a single-handed steering motion) were employed. Implantation inclinations were compared based on the maximum bone-implant interface distraction detected after loading.

RESULTS

The implant-bone distraction was greatest in the 130° neck-shaft angle implantation cases. All implant loading scenarios elicited significantly lower micromotion magnitudes when neck-shaft angle was increased (P = .0001). With every 5° increase in neck-shaft angle, there was an average 17% reduction in bone-implant distraction.

CONCLUSIONS

The neck-shaft angle of implantation for a stemless reverse humeral component is a modifiable parameter that appears to influence time-zero implant stability. Lower, more varus, neck-shaft angles increase bone-implant distractions with simulated activities of daily living. It is therefore suggested that humeral head osteotomies at a higher neck-shaft angle may be beneficial to maximize stemless humeral component stability.

Anatomical shoulder replacements in young patients: A systematic review and meta-analysis

Introduction

Increasing numbers of young patients receive shoulder replacements. Greater information on outcomes is needed to inform implant choice. The aim of this study was to investigate the survivorship and clinical effectiveness of hemiarthroplasty and anatomical total shoulder arthroplasty (TSA) in patients younger than 65 years.

Method

A systematic review was performed of MEDLINE, EMBASE, CENTRAL, The Cochrane Database of Systematic Reviews and National Joint Registry reports. The primary outcomes were implant survival and change in perioperative shoulder scores.

Results

Meta-analysis of implant survivorship was performed of six studies reporting on 416 patients. Implant survival was 86.1% (72.1,100) at 10 years for hemiarthroplasty and 82.3% (64.6,100) for TSA. 20 year survival was 80.0% for hemiarthroplasty (72.5,87.4) and 75.0% (56.9,93.1) for TSA. Ten studies were included in the meta-analysis of shoulder scores, multiple instruments were used. The standardised mean difference between pre-operative and post-operative shoulder scores was 2.15 (1.95, 2.35) for TSA at 4.2-4.9 years, and 2.72 (1.98,3.47) for hemiarthroplasty at 3.8-6 years.

Conclusion

Over 80% of shoulder replacements last more than 10 years, and 75% last more than 20 years. Significant improvements in shoulder scores are shown at all time points.

Can convertible metal-backed glenoid components replace cemented polyethylene glenoid components in anatomical total shoulder arthroplasty?

BACKGROUND

Anatomical total shoulder arthroplasty (aTSA) has been used to manage degenerative diseases such as primary osteoarthritis. An increase in the use of this procedure has led to several developments in humeral and glenoid components to improve patient outcomes. This study aimed to compare clinical and radiological outcomes of the newly-introduced convertible metal-backed glenoid components with cemented polyethylene glenoid components in aTSA, and to determine whether the new component would be comparable to a conventional one for reducing the burden of future revision or conversion surgeries.

METHODS

Medical records of fifty patients who underwent aTSA with at least two years of follow-up were retrospectively reviewed. Eighteen patients received convertible metal-backed glenoid components with vitamin E1-coated liner (MB group), while thirty-two patients received conventional cemented polyethylene glenoid components (PE group). Pre- and postoperative clinical and radiological outcomes (acromion-greater tuberosity angle [AGA] and humeral lateral offset [LO]) at final follow-up were assessed. Radiolucent lines (RLLs) and loosening around the humeral and glenoid components were also evaluated.

RESULTS

Clinical outcomes improved after surgery in both groups (all p < 0.001). The arc of rotation measured by AGA improved postoperatively in both groups (all p < 0.001), and AGA and LO were not different according to the type of glenoid components (all p > 0.05). Overall complication rates including RLLs of PE and MB groups were 43.8% (14/32) and 16.7% (3/18), respectively (p = 0.031). Although the PE group had more RLLs than did the MB group (p < 0.05), related symptoms and/or glenoid implant loosening were not observed in both groups. Subscapularis failure occurred in two patients in the PE group and in one in the MB group.

CONCLUSION

The convertible metal-backed glenoid implant with vitamin E1-coated liner may be a good alternative for considering the potential for an easier conversion to reverse total shoulder arthroplasty.

Comparison of clinical outcomes of revision reverse total shoulder arthroplasty for failed primary anatomic vs. reverse shoulder arthroplasty

Background

Both anatomic total shoulder arthroplasty (aTSA) and reverse total shoulder arthroplasty (RTSA) are being increasingly performed. In the event of a complication necessitating revision, RTSA is more commonly performed in both scenarios. The purpose of this study was to compare clinical outcomes between patients undergoing revision RTSA for failed primary anatomic versus reverse total shoulder arthroplasty.

Methods

We performed a retrospective review of a prospective single-institution shoulder arthroplasty database. All revision RTSAs performed between 2007 and 2019 with a minimum 2-year clinical follow-up were initially included. After excluding patients with a preoperative diagnosis of infection, an oncologic indication, or incomplete outcomes assessment, we included 45 revision RTSAs performed for failed primary aTSA and 15 for failed primary RTSA. Demographics, surgical characteristics, active range of motion (external rotation [ER], internal rotation, forward elevation [FE], abduction), outcome scores (American Shoulder and Elbow Surgeons score, Constant Score, Shoulder Pain and Disability Index, Simple Shoulder Test, and University of California, Los Angeles score), and the incidence of postoperative complications was compared between groups.

Results

Primary aTSA was most often indicated for degenerative joint disease (82%), whereas primary RTSA was more often indicated for rotator cuff arthropathy (60%). On bivariate analysis, no statistically significant differences in any range of motion or clinical outcome measure were found between revision RTSA performed for failed aTSA vs. RTSA. On multivariate linear regression analysis, revision RTSA performed for failed aTSA vs. RTSA was not found to significantly influence any outcome measure. Humeral loosening as an indication for revision surgery was associated with more favorable outcomes for all four range of motion measures and all five outcome scores assessed. In contrast, an indication for revision of peri-prosthetic fracture was associated with poorer outcomes for three of four range of motion measures (ER, FE, abduction) and four of five outcome scores (Constant, Shoulder Pain and Disability Index, Simple Shoulder Test, University of California, Los Angeles). A preoperative diagnosis of fracture was associated with a poorer postoperative range of motion in ER, FE, and abduction, but was not found to significantly influence any outcome score. However, only two patients in our cohort had this indication. Complication and re-revision rates after revision RTSA for failed primary aTSA and RTSA were 27% and 9% vs. 20% and 14% (P = .487 and P = .515), respectively.

Conclusion

Clinical outcomes of patients undergoing revision RTSA for failed primary shoulder arthroplasty did not significantly differ based on whether aTSA or RTSA was initially performed. However, larger studies are needed to definitively ascertain the influence of the primary construct on the outcomes of revision RTSA.

Radiologic midterm results of cemented and uncemented glenoid components in primary osteoarthritis of the shoulder: a matched pair analysis

INTRODUCTION

Cemented all-polyethylene glenoid components are considered the gold standard in anatomic shoulder arthroplasty. New designs of cementless metal backed glenoid components showed promising early and midterm results. The aim of this matched-pair analysis was to compare the radiologic results of two cemented glenoid components and a cementless glenoid component in patients with primary osteoarthritis (OA).

METHODS

Sixty shoulders were clinically and radiologically evaluated after a mean follow-up of 59 months. Mean patient age was 70.4 years at surgery. Based on the design of the glenoid component (keel, peg, MB), 3 groups with, respectively, 20 shoulders were formed according to the matching criteria time of follow-up, patient age and gender. RLL and osteolysis in anteroposterior and axillary X-ray images were quantified and combined in a radiologic score (R-Score). Higher scores expressed worse radiologic outcomes. Further radiological parameters such as lateral glenohumeral offset (LGHO) and subluxation index were measured according to Walch. The functional results were documented using the age and gender normalized Constant-Murley score.

RESULTS

Postoperative R-Score was highest in pegged components (peg: 5.7, keel: 2.4, MB: 1.6; p < 0.001) when combining both radiographs and after separate analysis of anteroposterior radiographs. MB glenoids had the lowest R-score in axillary radiographs (peg: 2.2, keel: 1.4, MB: 0.6; MB vs. keel: p = 0.004, MB vs peg: p < 0.001). RLL were more common (p = 0.004) and severe (p = 0.005) in pegged glenoids (RLL incidence: 77.8%, RLL-score: 2.5) than in MB glenoids (RLL incidence: 30%, RLL-score 0.7) and tended (p = 0.084) to have a higher RLL-score than keeled glenoids (RLL incidence: 63.2%, RLL-score:1.4). Both the osteolysis score (keel vs. peg: p < 0.001, MB vs. peg p < 0.001) and the incidence of osteolysis (keel vs. peg: p = 0.008, MB vs peg: p = 0.003) were significant higher in pegged glenoids (peg: osteolysis score: 3.2, osteolysis incidence: 100%; keel: osteolysis score: 1.0, osteolysis incidence: 63.2%, MB: osteolysis score: 0.9, osteolysis incidence: 60%), while the osteolysis score in axillary images was lowest for MB glenoids (peg: 1.2, keel: 0.9, MB: 0.4; peg vs. MB: p = 0.009, keel vs. MB: p = 0.047). Osteolysis in the central axillary zone was least common in MB glenoids (peg: 50%, keel: 47.4%, MB: 15%; peg vs. MB p = 0.035, keel vs. MB p = 0.041). LGHO was highest in MB glenoids (peg: 54.1, keel: 54.5, MB: 57.8; p < 0.001) but did not increase radiographic loosening (r = 0.007; p = 0.958). Preoperative posterior humeral head subluxation seemed to affect incidence of RLL negatively (pre-op posterior decentered 64.3%, pre-op centered 31.9%; p = 0.201) but did not reach statistical significance.

CONCLUSION

Pegged glenoid components had a concerning rate of RLL and osteolysis. MB glenoid components had a better outcome in axillary radiographs concerning RLL and osteolysis. Increased LGHO did not increase radiographic loosening.

LEVEL OF EVIDENCE

Retrospective comperative treatment study Level III.

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.

The addition of preoperative three-dimensional analysis alters implant choice in shoulder arthroplasty

BACKGROUND

The primary objective of the present study was to investigate how preoperative imaging modalities including 3D computed tomography (CT) scans with preoperative planning software affect implant choice for shoulder arthroplasty.

METHODS

X-ray, uncorrected 2D CT scans, and 3D CT scans from 21 patients undergoing primary arthroplasty were reviewed by five shoulder surgeons. Each surgeon measured glenoid version, inclination and humeral head subluxation, and then selected an anatomic or reverse shoulder arthroplasty implant based only on these imaging parameters. Each surgeon virtually positioned the implant. Agreement between surgeons and changes in plan for individual surgeons between imaging modalities were assessed.

RESULTS

Average measurements of native version, inclination, and subluxation were similar across all imaging modalities with very good interobserver reliability. Overall, there was a high rate of variability in choice of implant depending on imaging modality. Agreement on implant selection between surgeons improved from 68.6% using x-ray to 80.0% with 3D CT. Introducing age added significant variability, reducing agreement on implant choice to 61.0% with 3D CT.

CONCLUSIONS

The use of preoperative 3D planning changes implant choice in nearly one-third of cases compared to plain radiographs and improves surgeon agreement on implant choice compared to x-ray and 2D CT.Level of evidence: 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.

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.

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.

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.