Factors Influencing Outcome After Shoulder Arthroplasty (FINOSA Study): Protocol of a Prospective Longitudinal Study With Randomized Group Allocation.

Background: There is an increasing need for evidence-based postoperative rehabilitation strategies to optimize patient outcome. Knowledge of potential prognostic factors could steer the development of rehabilitation protocols and could result in better treatment outcomes and higher patient satisfaction.

Objective: This study aimed to investigate which potential prognostic factors predict baseline shoulder pain and function and its evolution in the first 2 years following surgery, in patients with total shoulder arthroplasty. The secondary objective is to investigate which potential prognostic factors predict baseline quality of life and its evolution in the first two years following surgery.

Methods: To reach the aims of this project, a prospective longitudinal study, running from January 2020 to March 2025, will be carried out with a follow-up of 48 months. Patients will be randomized based on sling wear. We will study factors such as shoulder function, patient expectations, psychosocial factors, lifestyle factors, sling wear, soft tissue integrity, and physiotherapy treatment. Test moments will take place preoperatively, at 6 weeks, 12 weeks, 6 months, 12 months, and 24 months. Descriptive statistics will be used to describe the patient population characteristics. Based on literature review, expert opinion, and univariate analyses, potential prognostic factors will be chosen as covariates. A mixed regression model for repeated measures will be used to assess both the evolution of the Shoulder Pain and Disability Index within persons from baseline over time and the differences in evolution between participants. Correlation analyses will be used to investigate associations between the other outcome measures such as the Constant and Murley Score, shoulder range of motion, shoulder muscle strength, and proprioception, and the primary outcome measure, the Shoulder Pain and Disability Index score. Potential prognostic factors not included in the model will be presented in a descriptive manner.

Results: Data collection started in January 2020. In April 2023 the sample size was reached. Data collection will end in April 2025. Analyses will follow when data collection is completed.

Conclusions: Knowledge of potential prognostic factors will have implications toward better rehabilitation strategies of patients after total shoulder arthroplasty.

Trial registration: ClinicalTrials.gov NCT04258267; https://clinicaltrials.gov/study/NCT04258267.

International registered report identifier (irrid): DERR1-10.2196/56522.