Effects of Biceps Rerouting on In Vivo Glenohumeral Kinematics in the Treatment of Large-to-Massive Rotator Cuff Tears.

Background: Arthroscopic repair with the biceps rerouting (BR) technique has been determined to lead to promising clinical and biomechanical outcomes for treating large-to-massive rotator cuff tears (LMRCTs). However, the in vivo effects of BR on glenohumeral kinematics during functional shoulder movements have not been fully elucidated.

Purpose: To investigate whether BR provides a better restoration of shoulder kinematics compared with conventional rotator cuff repair (RCR).

Study design: Controlled laboratory study.

Methods: Patients who underwent either repair with the BR technique (BR group) or RCR alone (RCR group) for treating LMRCTs between January 2021 and May 2022 were enrolled. They underwent a 1-year postoperative kinematic evaluation of bilateral shoulders by performing scapular-plane abduction with a dual fluoroscopic imaging system. Glenohumeral translation in the superior-inferior (S-I) and anterior-posterior (A-P) directions was assessed in shoulder abduction at 10° increments. Moreover, the mean, maximum, minimum, and range of glenohumeral translation were calculated throughout the entire movement.

Results: A total of 9 patients were enrolled in each group for final analysis, and baseline characteristics were comparable between the groups. In the RCR group, compared with contralateral shoulders, the operative shoulders showed increased superior humeral head translation during lower abduction angles of 30° to 50° (all P≤ .004), with a greater maximum (P = .014) and a larger range (P = .002) for S-I translation throughout the entire movement. In the BR group, no significant differences between operative and contralateral shoulders were detected in any kinematic variables for S-I translation (all P≥ .132); however, the operative shoulders exhibited a larger maximum (P = .031), a smaller minimum (P = .008), and a larger range (P < .001) for A-P translation throughout the entire movement compared with the contralateral shoulders.

Conclusion: BR successfully reduced residual superior humeral head translation compared with conventional RCR and restored normal S-I glenohumeral kinematics in the treatment of LMRCTs. However, A-P glenohumeral kinematics was not fully restored after BR, and its effect on long-term clinical outcomes requires further investigation.

Clinical relevance: BR can be a promising technique to treat LMRCTs. However, its potential adverse effects on A-P glenohumeral kinematics should not be ignored, requiring further clinical evidence to determine long-term outcomes.