The Shoulder Arthroplasty Smart Score Correlates Well With Legacy Outcome Scores Without a Ceiling Effect

Does achieving clinically important thresholds after first shoulder arthroplasty predict similar outcomes of the contralateral shoulder?

BACKGROUND

Patients are increasingly undergoing bilateral total shoulder arthroplasty (TSA). At present, it is unknown whether success after the first TSA is predictive of success after contralateral TSA. We aimed to determine whether exceeding clinically important thresholds of success after primary TSA predicts similar outcomes for subsequent contralateral TSA.

METHODS

We performed a retrospective review of a prospectively collected shoulder arthroplasty database for patients undergoing bilateral primary anatomic (aTSA) or reverse (rTSA) total shoulder arthroplasty since January 2000 with preoperative and 2- or 3-year clinical follow-up. Our primary outcome was whether exceeding clinically important thresholds in the American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) score for the first TSA was predictive of similar success of the contralateral TSA; thresholds for the ASES score were adopted from prior literature and included the minimal clinically important difference (MCID), the substantial clinical benefit (SCB), 30% of maximal possible improvement (MPI), and the patient acceptable symptomatic state (PASS). The PASS is defined as the highest level of symptom beyond which patients consider themselves well, which may be a better indicator of a patient's quality of life. To determine whether exceeding clinically important thresholds was independently predictive of similar success after second contralateral TSA, we performed multivariable logistic regression adjusted for age at second surgery, sex, BMI, and type of first and second TSA.

RESULTS

Of the 134 patients identified that underwent bilateral shoulder arthroplasty, 65 (49%) had bilateral rTSAs, 45 (34%) had bilateral aTSAs, 21 (16%) underwent aTSA/rTSA, and 3 (2%) underwent rTSA/aTSA. On multivariable logistic regression, exceeding clinically important thresholds after first TSA was not associated with greater odds of achieving thresholds after second TSA when success was evaluated by the MCID, SCB, and 30% MPI. In contrast, exceeding the PASS after first TSA was associated with 5.9 times greater odds (95% confidence interval 2.5-14.4, P < .001) of exceeding the PASS after second TSA. Overall, patients who exceeded the PASS after first TSA exceeded the PASS after second TSA at a higher rate (71% vs. 29%, P < .001); this difference persisted when stratified by type of prosthesis for first and second TSA.

CONCLUSIONS

Patients who achieve the ASES score PASS after first TSA have greater odds of achieving the PASS for the contralateral shoulder regardless of prostheses type.

Prognostic value of the Walch classification for patients before and after shoulder arthroplasty performed for osteoarthritis with an intact rotator cuff

BACKGROUND

The Walch classification is commonly used by surgeons when determining the treatment of osteoarthritis (OA). However, its utility in prognosticating patient clinical state before and after TSA remains unproven. We assessed the prognostic value of the modified Walch glenoid classification on preoperative clinical state and postoperative clinical and radiographic outcomes in total shoulder arthroplasty (TSA).

METHODS

A prospectively collected, multicenter database for a single-platform TSA system was queried for patients with rotator cuff-intact OA and minimum 2 year follow-up after anatomic (aTSA) and reverse TSA (rTSA). Differences in patient-reported outcome scores (Simple Shoulder Test, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form, Shoulder Pain and Disability Index, visual analog scale for pain, Shoulder Function score), combined patient-reported and clinical-input scores (Constant, University of California-Los Angeles shoulder score, Shoulder Arthroplasty Smart Score), active range of motion values (forward elevation [FE], abduction, external rotation [ER], internal rotation [IR], and radiographic outcomes (humeral and glenoid radiolucency line rates, scapula notching rate) were stratified and compared by glenoid deformity type per the Walch classification for aTSA and rTSA cohorts. Comparisons were performed to assess the ability of the Walch classification to predict the preoperative, postoperative, and improved state after TSA.

RESULTS

1008 TSAs were analyzed including 576 aTSA and 432 rTSA. Comparison of outcomes between Walch glenoid types resulted in 15 pairwise comparisons of 12 clinical outcome metrics, yielding 180 total Walch glenoid pairwise comparisons for each clinical state (preoperative, postoperative, improvement). Of the 180 possible pairwise Walch glenoid type and metric comparisons studied for aTSA and rTSA cohorts, <6% and <2% significantly differed in aTSA and rTSA cohorts, respectively. Significant differences based on Walch type were seen after adjustment for multiple pairwise comparisons in the aTSA cohort for FE and ER preoperatively, the Constant score postoperatively, and for abduction, FE, ER, Constant score, and SAS score for pre- to postoperative improvement. In the rTSA cohort, significant differences were only seen in abduction and Constant score both postoperatively and for pre- to postoperative improvement. There were no statistically significant differences in humeral lucency rate, glenoid lucency rate (aTSA), scapular notching rate (rTSA), complication rates, or revision rates between Walch glenoid types after TSA.

CONCLUSION

Although useful for describing degenerative changes to the glenohumeral joint, we demonstrate a weak association between preoperative glenoid morphology according to the Walch classification and clinical state when evaluating patients undergoing TSA for rotator cuff-intact OA. Alternative glenoid classification systems or predictive models should be considered to provide more precise prognoses for patients undergoing TSA for rotator cuff-intact OA.

Quantifying success after reverse total shoulder arthroplasty: the substantial clinically important percentage of maximal possible improvement

BACKGROUND

Changes in preoperative to postoperative outcome scores are often used to quantify success after reverse total shoulder arthroplasty (rTSA). However, ceiling effects associated with many outcome scores limit the ability to differentiate success among high-functioning patients. The percentage of maximal possible improvement (%MPI) was introduced to simplify and better stratify patient success. The primary purpose of this study was to define the %MPI thresholds associated with substantial clinical improvement following primary rTSA and compare the rates of success as defined by those achieving the substantial clinical benefit (SCB) compared to the 30% MPI for different outcome scores.

METHODS

A retrospective review was performed of an international shoulder arthroplasty database between 2003 and 2020. All primary rTSAs performed using a single implant system with a minimum 2-year follow-up were reviewed. Preoperative and postoperative outcome scores were evaluated for all patients to calculate improvement. Six outcome scores were assessed: the Simple Shoulder Test (SST), Constant, American Shoulder and Elbow Surgeons (ASES), University of California Los Angeles (UCLA), Shoulder Pain and Disability Index (SPADI), and Shoulder Arthroplasty Smart (SAS) scores. The proportion of patients achieving the SCB and 30% MPI was determined for each outcome score. Thresholds for the substantial clinically important %MPI (SCI-%MPI) were calculated using an anchor-based method for each outcome score and stratified by age and sex.

RESULTS

Of total, 2573 shoulders with a mean follow-up of 47 months were included. Outcome scores with known ceiling effects (SST, ASES, UCLA, SPADI) had higher rates of patients achieving the 30% MPI compared to scores without ceiling effects (Constant, SAS). However, scores without ceiling effects had higher rates of patients achieving the SCB. The SCI-%MPI differed among outcome scores, and mean values were 47% for the SST, 35% for the Constant score, 50% for the ASES score, 52% for the UCLA score, 47% for the SPADI score, and 45% for the SAS score. The SCI-%MPI increased in patients older than 60 years (P < .001) except for the SAS and Constant scores. SCI-%MPI was greater in females for all scores assessed except the Constant and SPADI scores (P < .001 for all). The higher SCI-%MPI thresholds in these populations mean that these patients required a greater fraction of the MPI to have substantial improvement.

CONCLUSION

The %MPI judged relative to patient-reported substantial clinical improvement offers an alternative method to quickly assess improvements across patient outcome scores. Given considerable variation in the %MPI corresponding to substantial clinical improvement, we recommend utilizing score-specific estimates of the SCI-%MPI to gauge success when evaluating patients undergoing primary rTSA.