Abstract
Background: There is a relative paucity of studies examining how the superior capsule reconstruction (SCR) may alter the kinematics of the glenohumeral joint capsule itself, specifically with respect to rotation and translation in the anterior-posterior and superior-inferior planes. This then raises the possibility that the SCR may be having unintended consequences on glenohumeral kinematics. The purpose of this study was to quantify the glenohumeral joint kinematics following fascia lata SCR (FL-SCR). We hypothesized that the FL-SCR will not restore the glenohumeral joint kinematics to the intact condition. Methods: Eight fresh cadaver shoulders were studied using a custom shoulder testing system. Rotational range of motion (ROM) was measured with 2.2Nm of torque. Glenohumeral kinematics throughout the ROM were then measured at 0, 20, and 40 glenohumeral abduction. Anterior-posterior translation and superior-inferior translation from loading with 10, 15, and 20N in each direction was also measured. There were 3 testing conditions: (1) intact rotator cuff, (2) massive rotator cuff tear (MCT), and (3) MCT with FL-SCR. A repeated measures analysis of variance with a Bonferroni correction was used for statistical analysis. Results: The total ROM was increased with MCT at 0, 20, and 40 degrees of abduction. FL-SCR restored total ROM to the intact state. FL-SCR shifted the humeral head inferiorly compared to the intact condition at 0 degrees of abduction. MCT resulted in increased anterior-posterior and superior-inferior translation; FL-SCR restored translation to intact levels. Conclusion: FL-SCR restores glenohumeral translations but alters glenohumeral kinematics in that it shifts the humeral head inferiorly compared to the intact rotator cuff state at low levels of abduction. © 2024 Journal of Shoulder and Elbow Surgery Board of Trustees