Intra- and inter-rater reliability of range of motion, muscle strength and proprioception measurements in patients with total shoulder arthroplasty.

Purpose: The purpose of this study is to evaluate the inter- and intra-reliability of measurements for shoulder range of motion, muscle strength, and proprioception in patients with shoulder arthroplasty, assessing both the prosthetic and healthy sides.

Methods: A test-retest design assessing intra- and inter-rater reliability within a single session of measurements for shoulder range of motion, strength, and proprioception. The study included 24 total shoulder arthroplasty patients, 12 months post-operative.

Results: Intraclass correlation coefficients (ICCs) for shoulder range of motion (ROM) and shoulder muscle strength measurements ranged from 0.73 to 0.94 for inter-rater reliability, reflecting moderate to excellent reliability. Weighted Kappa values for functional internal and external rotation showed moderate to almost perfect agreement, ranging from 0.57 to 0.85. For intra-rater reliability, ICCs values for ROM and muscle strength ranged from 0.86 to 0.97, reflecting good to excellent reliability and weighted kappa values showed moderate to perfect agreement, ranging from 0.52 to 1. Measurements for proprioception were largely unreliable, with ICCs ranging from 0 to 0.71.

Conclusion: Thus, the measurements demonstrate strong reliability for ROM and muscle strength, making it a valuable tool for clinical follow-up. The proprioception component, however, requires further research and development.