[Evaluation of a simple test for shoulder function in patients with surgically treated rotator cuff injuries]

To assess overall shoulder function a simple examination of the range of motion and strength may not be sufficiently representative. because the shoulder in its daily use is often required for repetitive activities, fatigue at an early stage could be a sign of disturbed shoulder function. Therefore the shoulder function test (SFT) was created to incorporate the factor time into shoulder assessment. With this study the SFT was evaluated for its clinical use in the prospective follow-up of a series of patients operated on for rotator cuff tears.

Using forward flexion, the patient had to lift a 500-g weight onto a shelf placed at a height which he could reach with his extended arm. The achieved height (5 levels possible) and the time he needed for 5 repetitions were recorded. The SFT value was calculated by division of the time required by the level of the reached shelf. Thus, a lower SFT score represents a better shoulder function. This was tested on 45 patients prior to rotator cuff repair and at 3, 6 and 12 months postoperatively. As validation the SF-36 and the Constant score were evaluated in parallel. Construct, criterion, content and discriminative validity and responsiveness were calculated Results: At all assessments the SFT correlated with the Constant score (r = - 0.47 to r = - 0.62) and the SF-36 (r = - 0.26 to r = - 0.61) demonstrating construct validity. As criterion validity the SFT correlated with the reported pain (r = 0.34 to r = 0.61), patients' self-estimation (r = 0.38 to r = 0.59) and doctors' estimation of the patients shoulder function (r = 0.36 to r = 0.54). Known groups validity was positive as the SFT could differentiate between shoulders with and without rotator cuff tears. The SFT demonstrated a good responsiveness with significant improvement (p = 0.01) after rotator cuff repair.

Repetitive forward flexion is an important function of the shoulder in daily activities. The SFT allows a reliable and valid quantitative measurement of this function. In order to improve functional assessment of the shoulder and scoring we would recommend using this patient- and function-orientated test in combination with the Constant score to document the current status of shoulder function.