Increased use of total shoulder arthroplasty for osteoarthritis and improved patient-reported outcome in Denmark, 2006-2015: a nationwide cohort study from the Danish Shoulder Arthroplasty Registry

Outcomes of patients undergoing anatomical total shoulder arthroplasty with augmented glenoid components - a systematic review

Background

Glenoid loosening is an issue in anatomic total shoulder arthroplasty (a-TSA). This has been attributed to abnormal glenoid anatomy, common among these patients. Different alternatives have been proposed to tackle glenoid bone loss and restore joint alignment with augmented glenoid implants being increasingly used to deal with this problem. This systematic review aims to evaluate the clinical and radiological outcomes of patients undergoing augmented glenoid a-TSAs. Our hypothesis was that augmented glenoid components will lead to good patient outcomes with a low incidence of complications and revision procedures.

Methods

MEDLINE, EMBASE, CENTRAL and CINHAL were searched from inception to February 2022 for information pertaining to outcomes of patients undergoing a-TSA with augmented glenoid implants.

Results

Eighteen studies reported on outcomes of 814 a-TSA (800 participants) with a mean follow-up of 3.7 years. Most studies (67%) were Type IV level of evidence. Almost 70% of participants underwent an a-TSA secondary to primary glenohumeral osteoarthritis. Most glenoids were type B2 (73%). Augmented glenoids material was mostly all-polyethylene (81%) with full wedge (45%) and stepped components (38%) designs being the most common. Most studies reported good clinical outcomes. 17 patients (4%) underwent a revision surgery.

Conclusions

Our review found that patients undergoing a-TSA with augmented glenoid components report good outcomes at short-to-mid-term follow-up. Further research is warranted to determine if such outcomes remain similar in long term.

Level of evidence

Level III, Systematic Review of Therapeutic Studies.

Total shoulder arthroplasty in France: An analysis of trends between 2009 and 2019 and projections to the year 2070

BACKGROUND

Over the past decades, total shoulder arthroplasty (TSA) procedures have steadily increased in the United States and Europe. In France, the number of shoulder surgeries rose by 24.5% between 2012 and 2018, but no study has yet analyzed TSA trends based on patient characteristics. Therefore, the aim of our study was to use the French healthcare database to (1) analyze growth trends based on the patient's sex, age, and comorbidity profile and (2) estimate the most appropriate incidence rate (IR) projections to the year 2070.

HYPOTHESIS

We hypothesize that in France, the upward trends are different for each sex and age group.

MATERIALS AND METHODS

This study was conducted in France from 2009 to 2019 based on the French healthcare database (SNDS), which contains all nationwide procedures. Patients were analyzed by sex, age group (<65 years, 65-74 years, ≥75 years), and comorbidity profile (4 levels). IR trends per 100,000 population were inferred by patient age, sex, and comorbidity using data from the French hospital discharge database (PMSI) and population forecasts and censuses from the French National Institute of Statistics and Economic Studies (INSEE). Linear, Poisson, logistic, and Gompertz projection models were created to forecast IRs to the year 2070.

RESULTS

Between 2009 and 2019, there was a sharper increase in IR in males (+155%; from 6.0 to 15.3) than in females (+118%; from 16.2 to 35.3) across all age groups. This increase was most significant in those younger than 65 years (+112%; from 2.3 to 4.9), in both males (+129%; from 2.1 to 4.8) and females (+99%; from 2.5 to 5.0). From 2012 to 2019, the proportion of patients with mild comorbidities increased by +92% (from 5,435 to 10,410 TSAs, i.e., from 56% to 61% of total procedures), unlike the other comorbidity profiles. All the projections modeled the data from 2009 to 2019 with minor deviations. However, the logistic projection was the most likely, with a 45% increase in the IR for the overall population by 2070 (from 17,175 to 25,338 TSAs), which will start to plateau in 2050.

CONCLUSION

The IR has risen sharply in the overall population, as in all age, sex, and comorbidity categories, with the most significant growth seen in the<65 and 65-74 age groups and a shift toward patients with milder comorbidities. According to our projections, the IR will continue to be more significant in older patients, except for males, for whom the IR for those 65 to 74 years old will exceed that of those 75 and older around 2030. In the longer term, the IRs follow a logistic trend, reaching a plateau around 2050. Therefore, an increase in healthcare burden is to be expected to meet the growing demand for TSAs.

LEVEL OF EVIDENCE

IV; Descriptive epidemiological study.

Risk of prolonged postoperative opioid use after elective shoulder replacement: a nationwide cohort study of 5,660 patients from the Danish Shoulder Arthroplasty Registry

BACKGROUND AND PURPOSE

Several studies from the United States report an increased risk of prolonged opioid use after shoulder replacement. We aimed to determine the incidence and risk factors of prolonged opioid use after elective shoulder replacement in a nationwide Danish population.

METHODS

All primary elective shoulder arthroplasties reported to the Danish Shoulder Arthroplasty Registry (DSR) from 2004 to 2020 were screened for eligibility. Data on potential risk factors was retrieved from the DSR and the National Danish Patient Registry while data on medication was retrieved from the Danish National Health Service Prescription Database. Prolonged opioid use was defined as 1 or more dispensed prescriptions on and 90 days after date of surgery (Q1) and subsequently 1 or more dispensed prescriptions 91-180 days after surgery (Q2). Preoperative opioid use was defined as 1 or more dispensed prescriptions 90 days before surgery. Logistic regression models were used to estimate risk factors for prolonged opioid use.

RESULTS

We included 5,660 patients. Postoperatively 1,584 (28%) patients were dispensed 1 or more prescriptions in Q1 and Q2 and were classified as prolonged opioid users. Among the 2,037 preoperative opioid users and the 3,623 non-opioid users, 1,201 (59%) and 383 (11%) respectively were classified as prolonged users. Preoperative opioid use, female sex, alcohol abuse, previous surgery, high Charlson Comorbidity index, and preoperative use of either antidepressants, antipsychotics, or benzodiazepines were associated with increased risk of prolonged opioid use.

CONCLUSION

The incidence of prolonged opioid use was 28%. Preoperative use of opioids was the strongest risk factor for prolonged opioid use, but several other risk factors were identified for prolonged opioid use.

High revision rate of metal-backed glenoid component and impact on the overall revision rate of stemless total shoulder arthroplasty: a cohort study from the Danish Shoulder Arthroplasty Registry

BACKGROUND AND PURPOSE

There is controversy regarding the results of stemmed and stemless total shoulder arthroplasty (TSA) used for osteoarthritis. Therefore, we aimed to compare revision rates of stemmed and stemless TSA and to examine the impact of metal-backed glenoid components.

METHODS

We included all patients reported to the Danish Shoulder Arthroplasty Register from January 1, 2012 to December 31, 2022 with an anatomical TSA used for osteoarthritis. Primary outcome was revision (removal or exchange of components) for any reason.

RESULTS

3,338 arthroplasties were included. The hazard ratio for revision of stemless TSA adjusted for age and sex was 1.83 (95% confidence interval [CI] 1.21-2.78) with stemmed TSA as reference. When excluding all arthroplasties with a metal-backed glenoid component, the adjusted hazard ratio for revision of stemless TSA was 1.37 (CI 0.85-2.20). For the Eclipse stemless TSA system, the adjusted hazard ratio for revision of a metal-backed glenoid component was 8.75 (CI 2.40-31.9) with stemless Eclipse with an all-polyethylene glenoid component as reference.

CONCLUSION

We showed that the risk of revision of stemless TSAs was increased and that it was related to their combination with metal-backed glenoid components.

High rate of clinically relevant improvement following anatomical total shoulder arthroplasty for glenohumeral osteoarthritis

BACKGROUND

The minimal clinically important difference (MCID) is defined as the smallest meaningful change in a health domain that a patient would identify as important. Thus, an improvement that exceeds the MCID can be used to define a successful treatment for the individual patient.

AIM

To quantify the rate of clinical improvement following anatomical total shoulder arthroplasty for glenohumeral osteoarthritis.

METHODS

Patients were treated with the Global Unite total shoulder platform arthroplasty between March 2017 and February 2019 at Herlev and Gentofte Hospital, Denmark. The patients were evaluated preoperatively and 3 months, 6 months, 12 months, and 24 months postoperatively using the Western Ontario Osteoarthritis of the Shoulder index (WOOS), Oxford Shoulder Score (OSS) and Constant-Murley Score (CMS). The rate of clinically relevant improvement was defined as the proportion of patients who had an improvement 24 months postoperatively that exceeded the MCID. Based on previous literature, MCID for WOOS, OSS, and CMS were defined as 12.3, 4.3, and 12.8 respectively.

RESULTS

Forty-nine patients with a Global Unite total shoulder platform arthroplasty were included for the final analysis. Mean age at the time of surgery was 66 years (range 49.0-79.0, SD: 8.3) and 65% were women. One patient was revised within the two years follow-up. The mean improvement from the preoperative assessment to the two-year follow-up was 46.1 points [95% confidence interval (95%CI): 39.7-53.3, P < 0.005] for WOOS, 18.2 points (95%CI: 15.5-21.0, P < 0.005) for OSS and 37.8 points (95%CI: 31.5-44.0, P < 0.005) for CMS. Two years postoperatively, 41 patients (87%) had an improvement in WOOS that exceeded the MCID, 45 patients (94%) had an improvement in OSS that exceeded the MCID, and 42 patients (88%) had an improvement in CMS that exceeded the MCID.

CONCLUSION

Based on three shoulder-specific outcome measures we find that approximately 90% of patients has a clinically relevant improvement. This is a clear message when informing patients about their prognosis.

[Revision surgery in reverse shoulder arthroplasty : Management of the most common complications]

BACKGROUND

In recent years, the number of reverse shoulder arthroplasty implantations has increased continuously and a higher number of revision surgeries due to complications can be expected in the future. Current data show a mean complication rate for RSA of around 4%. The most common complications are instability, infection, component loosening, and periprosthetic fracture.

TREATMENT OPTIONS

Revision surgery for RSA is challenging, and an individual treatment plan is necessary. For prosthetic instability, different operative or non-operative treatment options are available. Revision surgery for periprosthetic infection with replacement of the prosthesis is usually necessary for infection management. The treatment of periprosthetic fractures is based on techniques of general fracture treatment and depends on the fracture type. Knowledge of complications and risk factors may decrease complication rates in primary reverse shoulder arthroplasty in the future.

Revision Rates and Associated Risk Factors after Shoulder Arthroplasty

This study aims at answering the following questions (1) How high is the revision rate after osteoarthritis-, and rotator cuff-related compared to proximal humerus fracture (PHF)-related shoulder arthroplasty? (2) What are the associated risk factors for a revision after shoulder arthroplasty? Shoulder arthroplasty procedures occurring between 1 January 2009 and 31 December 2019 were identified from the Medicare database. First, revision rates for PHF patients and age- and sex-matched non-fracture patients, grouped into osteoarthritis-related and rotator cuff-related arthroplasty, were compared. Second, revision rates between total shoulder arthroplasty and hemiarthroplasty after PHF were compared. Semiparametric Cox regression was applied, incorporating 23 demographic, clinical, and socioeconomic covariates, to investigate risk factors for revision surgery. Between the considered time period from 2009 through 2019, a total number of 47,979 PHFs was identified. A shoulder arthroplasty procedure was performed in n = 2639 (5.5%, 95%CI: 4.8-6.1) of the cases. The five-year survivorship of the implant was 96.3 (95%CI: 93.8-97.9) after hemiarthroplasty and 96.1% (05%CI: 94.2-97.3) after total shoulder arthroplasty. To compare the revision rates, n = 14,775 patients with osteoarthritis and n = 4268 patients with rotator cuff arthropathy, who received a shoulder arthroplasty, served as a non-fracture control group. Patients receiving a rotator cuff-related arthroplasty were more likely to require a revision compared to patients treated for osteoarthritis (HR: 1.27, 95%CI: 1.04-1.44, p = 0.018). Identified significant risk factors for revision surgery after shoulder arthroplasty included age ≤ 75 years, male sex, and osteoporosis. High implant survival was found for hemiarthroplasty and total shoulder arthroplasty for the treatment of PHF in elderly patients. The risk of revision surgery was elevated in patients receiving a rotator cuff-related arthroplasty as well as in patients with osteoporosis, male patients and patients older than 75 years.

Agreement between the American Shoulder and Elbow Surgeons Society Standardized Shoulder Assessment score (ASES) and the Oxford Shoulder Score (OSS) in patients presenting with shoulder pathology: A cohort analysis of the Clinical Quality Registry for Outcomes in Shoulder and Elbow Pathology (CROSEP) registry

Background

The choice of patient-reported outcome measure (PROM) used in shoulder studies varies based on clinician's preference and location. This creates difficulties when attempting to compare studies which have used different PROMs as their outcome measure. This study aims to assess the agreement between the American Shoulder and Elbow Surgeons score (ASES) and the Oxford Shoulder Score (OSS), and identify factors associated with agreement.

Methods

Patients with shoulder pathology were identified from a multi-cohort observational practice registry. 1050 paired ASES and OSS pre-treatment scores were prospectively collected. Linear regression was performed to assess the agreement between the PROMs. Mixed-effects analysis of variance was performed to assess the influence of factors associated with agreement.

Results

Regression for mean total and mean function ASES and OSS demonstrated good fit (adjusted R2 57.7%, P < 0.001; and 63.9%, P < 0.001). Mean pain subscore demonstrated a poorer fit (adjusted R2 39.4%, P < 0.001). Crosswalks to convert between mean scores were produced with reasonable precision. Veterans RAND 12-Item Health Survey score, age and diagnosis cohort influenced agreement.

Conclusion

Mean total and mean function ASES and OSS scores agree well with each other. This allows for a more informed comparison of studies using either PROMs as their outcome measure.

Can the Single Assessment Numeric Evaluation (SANE) be used as a stand-alone outcome instrument in patients undergoing total shoulder arthroplasty?

BACKGROUND AND HYPOTHESIS

There is no consensus as to which patient-determined shoulder outcome scores should be considered when analyzing patient outcomes for either clinical or research purposes. Use of multiple patient-determined outcomes may be redundant and cause increased responder burden. To date, the Single Assessment Numeric Evaluation (SANE) has not been widely accepted as a stand-alone shoulder-specific outcome measure. The hypothesis of this study was that the SANE would correlate with and be equal or superior in responsiveness to other outcome measures that have been used in a stand-alone fashion in patients undergoing total shoulder arthroplasty (American Shoulder and Elbow Surgeons [ASES], Western Ontario Osteoarthritis of the Shoulder [WOOS], and Simple Shoulder Test [SST] scores). In addition, it was hypothesized that the SANE would be more relevant to each patient than the ASES assessment, further supporting the use of the SANE as a stand-alone shoulder-specific outcome measure.

METHODS

A retrospective review of a database of patients undergoing total shoulder arthroplasty was performed, in which the SANE score was recorded simultaneously with the ASES, WOOS, and/or SST score. Correlations were determined using the Pearson coefficient. Subgroup analysis was performed to determine whether correlations differed in (1) preoperative outcome and (2) postoperative outcome determinations. Responsiveness was determined by calculating the standardized response mean and the effect size of all scores. The relevance of the SANE and ASES assessments was examined using the scores of 150 consecutive patients to determine the number of questions on each assessment that were not answered.

RESULTS

Correlation was excellent for the SANE score and the ASES score (n = 1447, r = 0.82, P < .0001), WOOS score (n = 1514, r = 0.83, P < .0001), and SST score (n = 1095, r = 0.81, P < .0001). The correlation of preoperative scores was moderate and that of postoperative scores was strong-moderate when the SANE score was compared with all 3 other scores. All scores were highly responsive, with standardized response mean values of 2.2 for the SANE score, 2.3 for the ASES score, 1.4 for the WOOS score, and 1.6 for the SST score. The effect size of the SANE score was 2.9; ASES score, 2.9; WOOS score, 2.9; and SST score, 2.3. One hundred percent of the SANE questions were answered completely compared with 61% of the ASES questions (P < .0001).

CONCLUSION

In patients undergoing total shoulder arthroplasty, the SANE score highly correlated with the WOOS, ASES, and SST scores, which have been used as stand-alone shoulder-specific outcome measures. The SANE score may provide the same information as the WOOS, ASES, and SST score regarding outcomes with a significant reduction in responder burden. It is logical that the SANE can be used as a stand-alone instrument for patients undergoing total shoulder arthroplasty.

Study protocol: Prosthesis versus Active (ProAct) exercise program in patients with glenohumeral osteoarthritis - a multicenter, randomized controlled trial

BACKGROUND AND PURPOSE

Total shoulder arthroplasty (TSA) and shoulder exercises are both effective treatments for reducing pain and improving function in glenohumeral osteoarthritis. However, the effectiveness of TSA has not been compared with non-surgical treatment in a randomized controlled trial. We will examine whether TSA followed bystandard postsurgical rehabilitation is superior to a 12-week exercise program in patients with primary glenohumeral OA who are eligible for unilateral TSA.

PATIENTS AND METHODS

In this Nordic multicenter randomized controlled clinical trial, patients with glenohumeral osteoarthritis eligible for TSA will be allocated to either TSA followed by usual care or exercise only. The exercise intervention comprises 12 weeks of exercise with one weekly physiotherapist-supervised session. Based on the sample size calculation, the trial needs to include 102 patients. Duration and outcome:  Recruitment was initiated in April 2021 and is expected to be completed by the end of March 2024. Primary outcome is patient-reported quality of life, measured as total WOOS score 12 months after initiation of treatment. The key secondary outcomes include patient-reported pain intensity at rest and during activity; Disabilities of the Arm, Shoulder, and Hand score (DASH); the use of analgesics during the previous week; and adverse events.

TRIAL REGISTRATION

The trial is approved by the Central Denmark Region Committee on Biomedical Research Ethics (Journal No 1-10-72-29-21) and by the Danish Data Protection Agency (Journal No 1-16-02-199-21). ClinicalTrials.gov Identifier: NCT04845074.

Outcomes of shoulder arthroplasty by year of index procedure: are we getting better?

BACKGROUND

The purpose of this study was to determine whether postoperative patient-reported outcomes improved over time following anatomic total shoulder arthroplasty (TSA) and reverse total shoulder arthroplasty (RTSA).

METHODS

We performed a retrospective analysis of prospectively collected patient-reported outcomes from our institution's registry between 2008 and 2018 (N = 1899). American Shoulder and Elbow Surgeons (ASES) scores at a minimum of 2 years postoperatively were required. Univariable linear models were used to test the association between year of surgery and improvement in ASES scores at 2- and 5-year follow-up, as well as any association with age, sex, primary or revision surgery, hand dominance, American Society of Anesthesiologists classification, rotator cuff status, primary diagnosis, and Walch classification. Multivariable models were created to analyze ASES score improvement by index year while controlling for significant factors.

RESULTS

In the univariable analysis, 5-year ASES difference scores increased each year by a mean of 1.65 (P < .001; 95% confidence interval [CI], 0.75-2.55) for TSA, 2.50 (P = .014; 95% CI, 0.52-4.49) for RTSA, and 1.64 (P < .001; 95% CI, 0.81-2.47) for the overall population. Patient sex, American Society of Anesthesiologists classification, rotator cuff status, primary diagnosis, Walch classification, and revision procedures were also significant factors affecting ASES scores. On multivariable analysis controlling for these factors, 5-year ASES difference scores were still significantly associated with year of surgery, increasing each year by a mean of 2.20 (P < .001; 95% CI, 0.91-3.50) for TSA, 4.83 (P < .001; 95% CI, 1.17-8.49) for RTSA, and 1.66 (P < .001; 95% CI, 0.81-2.51) for the entire population.

CONCLUSION

Both anatomic TSA and RTSA patients reported increasing ASES difference scores at 5-year follow-up as time passed. These findings may indicate that advances in shoulder arthroplasty have resulted in better patient outcomes over time. Further research is needed to clarify which factors influence improvements in outcomes, particularly for revision procedures.

Limited value of current shoulder arthroplasty registries in evidence-based shoulder surgery: a review of 7 national registries

National shoulder arthroplasty registries are currently used to assess incidence, indication, type of prosthesis and revision, but they seem to lack sufficient information to lead to evidence based decision-making in shoulder surgery. There appears to be a large difference in registered parameters and outcome measurement per country. First we investigated whether existing registries have sufficient common datasets to enable pooling of data. Second, we determined whether known risk factors for prosthetic failure are being recorded. Through a non-systematic literature review studies on registries were analyzed for included parameters. Seven national registries were scrutinized for the data collected and these were classified according to categories of risk factors for failure: patient-, implant and surgeon related, and other parameters. This shows a large heterogeneity of registered parameters between countries. The majority of parameters shown to be relevant to outcome and failure of shoulder prostheses are not included in the studied registries. International agreement on parameters and outcome measurement for registries is paramount to enable pooling and comparison of data. If we intend to use the registries to provide us with evidence to improve prosthetic shoulder surgery, we need adjustment of the different parameters to be included.

Mechanical complications and fractures after reverse shoulder arthroplasty related to different design types and their rates: part I

The initial reverse shoulder arthroplasty (RSA), designed by Paul Grammont, was intended to treat rotator cuff tear arthropathy in elderly patients. In the early experience, high complication rates (up to 24%) and revision rates (up to 50%) were reported.The most common complications reported were scapular notching, whereas clinically more relevant complications such as instability and acromial fractures were less commonly described.Zumstein et al defined a 'complication' following RSA as any intraoperative or postoperative event that was likely to have a negative influence on the patient's final outcome.High rates of complications related to the Grammont RSA design led to development of non-Grammont designs, with 135 or 145 degrees of humeral inclination, multiple options for glenosphere size and eccentricity, improved baseplate fixation which facilitated glenoid-sided lateralization, and the option of humeral-sided lateralization.Improved implant characteristics combined with surgeon experience led to a dramatic fall in the majority of complications. However, we still lack a suitable solution for several complications, such as acromial stress fracture. Cite this article: EFORT Open Rev 2021;6:1097-1108. DOI: 10.1302/2058-5241.6.210039.

Intermediate to long term results of stemless metaphyseal reverse shoulder arthroplasty: A five to nine year follow-up

BACKGROUND

Shoulder arthroplasty incidence is increasing as is the volume of revision surgeries. Revision surgery is easier if humeral bone stock is preserved with minimal bone defects and osteolysis. This has led to an increased focus on the development of various short stemmed and stemless implants which provides stable fixation whilst preserving humeral bone stock.

PURPOSE

To review the medium to long term clinical and radiological outcomes, complications and survival rates of a stemless reverse shoulder prosthesis.

PATIENTS AND METHOD

Patients with a minimum follow-up of 60 months following a reverse stemless shoulder arthroplasty were deemed eligible. Clinical and radiological data on twenty-one patients operated between 2009 and 2014 were recorded prospectively. Survivorship and patient recorded symptoms with the end point of revision surgery were recorded.

RESULTS

Mean follow-up of 78 months (60-114 months). Mean range of active elevation was 136° (80-170°). Mean range of active abduction and active external rotation was 122° (70-170°) and 47° (10-75°) respectively. Mean Oxford score improved from 12 pre-operatively to 44 at final follow up (p < 0.0001). Mean Constant Murley Score improved from 18 to 72 (p < 0.0001). Mean ADLEIR score of 13 pre-operatively increased to 32 post-operatively (p < 0.0001). Notching was seen in 23.5% of cases and no radiolucent areas were observed around the glenoid component. There were two cases of post traumatic peri-prosthetic fractures that were managed conservatively and one case of deep-seated infection that required a washout. The survivorship at the most recent follow-up was 100%.

CONCLUSION

The advantages of bone preservation with the stemless metaphyseal prosthesis combined with encouraging medium to long term clinical and radiological results are very promising, particularly with the improved post-operative patient satisfaction scores. This is the first study that reports the results with a minimum of 5 year follow-up and has the longest mean follow-up period.

CLINICAL RELEVANCE

The reverse stemless shoulder prosthesis is an effective and reliable option for elective shoulder arthroplasty.

Minimal Clinically Important Differences (MCID) for the Western Ontario Osteoarthritis of the Shoulder Index (WOOS) and the Oxford Shoulder Score (OSS)

Background

The minimal clinically important difference (MCID) is an important instrument in the interpretation of changes in patient-reported outcome measures (PROM). To our knowledge, no MCID of the Western Ontario Osteoarthritis of the Shoulder Index (WOOS) score has ever been reported and no studies have reported an MCID for the Oxford Shoulder Score (OSS) based on patients with glenohumeral osteoarthritis, treated with an anatomical total shoulder arthroplasty (aTSA). The aim of this study was to determine MCID for WOOS and OSS in a cohort of patients with glenohumeral osteoarthritis treated with an aTSA.

Methods

All patients treated with an aTSA for glenohumeral osteoarthritis at our institution between March 2017 and February 2019 were included. Each patient completed the WOOS and the OSS preoperatively and one year postoperatively. At one year, the patients were asked to rate their overall improvement on a 7-point scale. We used an anchor-based method as our primary method to calculate the MCID, supported by two different distribution-based methods.

Results

A total of 45 primary aTSA were included. The MCID of WOOS was 12.3 according to the anchor-based method and 14.2 and 10.3 according to the two distribution-based methods. The MCID of OSS was 4.3 according to the anchor-based method and 5.8 and 4.3 according to the two distribution-based methods.

Conclusion

The anchor-based method is considered superior to the distribution-based method, and therefore we advocate to use this as MCID. For patients with glenohumeral osteoarthritis treated with an aTSA, the MCID values were 12.3 points for WOOS and 4.3 points for OSS. To our knowledge, this is the first study to report a MCID value for WOOS and the first study to report a MCID value for OSS in this subgroup of patients.