Defining Recovery Trajectories after Shoulder Arthroplasty: A Latent Class Analysis of Patient Reported Outcomes.

Abstract Background Patients undergoing total shoulder arthroplasty (TSA) can have varying levels of improvement after surgery. As patients typically demonstrate a non-linear recovery trajectory, advanced analysis investigating the degrees of variation in outcomes is needed. Latent class analysis (LCA) is a mixed/multilevel model that estimates random slope variance to evaluate heterogeneity in outcome patterns among patient sub-groups and can be used to outline differing recovery trajectories. The purpose of this study was to determine recovery trajectory patterns after TSA and to identify factors that predict a given trajectory. Methods Data from a prospectively-collected single institutional database of patients undergoing anatomic and reverse TSA were utilized. Patients were included if they had American Shoulder and Elbow Surgeons (ASES) scores preoperatively, as well as postoperative scores at 6 weeks, 6 months, 1 year, and 2 years. Patients were excluded if they underwent a revision procedure or hemiarthroplasty, or for prior infection. LCA was used to subdivide the patient cohort into subclasses based on postoperative recovery trajectory. This was performed for all patients, as well as anatomic TSA and reverse TSA as separate groups. Unpaired Student’s t-tests, analysis of variance (ANOVA), and Fisher’s exact test were used to compare classes based on factors including age, body mass index (BMI), sex, preoperative diagnosis, and type of arthroplasty. Results A total of 244 TSAs were included in the final analysis – 89 anatomic TSA and 155 reverse TSA. In the combined group, LCA modeling revealed three patterns for recovery – Resistant Responders had low baseline scores (ASES 50) with excellent final results (ASES > 75). For anatomic TSA, we identified Delayed Responders with moderate baseline scores and a delayed response before ultimately achieving moderate final results, Steady Progressors with moderate baseline scores and a steady progression to achieve moderate final results, and High Performers who had moderate baseline scores and excellent final results. For reverse TSA, we identified Late Regressors with low baseline scores and poor final results, Steady Progressors with moderate baseline scores and moderate final results, and High Performers with moderate baseline scores and excellent final results. Conclusions Patients recover in a heterogenous manner following TSA. Through LCA we identified different recovery trajectories for patients undergoing anatomic TSA and reverse TSA.