# Association Between Upper Limb Dysfunction and Six-Month Postoperative Pain Following Mini-Open Synovectomy for Lateral Epicondylitis: A Retrospective Cross-Sectional Study

## TL;DR

This study found that patient-reported disability, not grip strength, is linked to postoperative pain six months after surgery for lateral epicondylitis.

## Contribution

The study identifies patient-reported outcomes as a better predictor of chronic postoperative pain than mechanical measures.

## Key findings

- The PREE-J score was independently associated with six-month postoperative pain intensity.
- Grip strength did not significantly correlate with pain intensity.
- The model explained 50% of the variance in pain intensity without multicollinearity.

## Abstract

Background

Refractory lateral epicondylitis (LE) often requires surgical intervention; however, the extent to which postoperative upper limb dysfunction contributes to chronic pain remains unclear. In this study, we aimed to investigate the association between postoperative upper limb dysfunction and pain intensity at six months following mini-open synovectomy for LE.

Methods

This single-center, retrospective, cross-sectional study included 28 elbows that met the predefined eligibility criteria between January 2020 and December 2023. The primary outcome was pain intensity at six months postoperatively, assessed using an 11-point numeric rating scale (NRS). Upper limb function at the same time point was evaluated using the Patient-Rated Elbow Outcome Measure Japanese Version (PREE-J), the Japanese Orthopaedic Association Elbow Study Group score, grip strength, and elbow joint range of motion (ROM). Model assumptions were evaluated using residual diagnostics (including Q-Q plots and the Shapiro-Wilk test of standardized residuals). Univariate linear regression analysis was performed to examine the associations between each functional measure and pain intensity. A pre-specified multivariate linear regression model incorporating the PREE-J score and grip strength was subsequently fitted to evaluate their independent associations with the six-month NRS score.

Results

In the forced entry multivariable linear regression model, the PREE-J score was independently associated with the six-month NRS score, whereas grip strength showed no significant association. The model explained 50% of the variance in the pain intensity, with no evidence of multicollinearity.

Conclusions

At six months following mini-open synovectomy for LE, postoperative pain was independently associated with patient-reported disability as measured by the PREE-J, whereas grip strength was not significantly associated with pain intensity. Therefore, subjective functional impairment may more accurately reflect the postoperative pain burden, compared with isolated mechanical measures. A comprehensive functional assessment incorporating the PREE-J may facilitate the early identification of patients at risk of persistent pain and support the development of individualized rehabilitation strategies.