Biomechanical analysis comparing a traditional superior-inferior arthroscopic rotator interval closure with a novel medial-lateral technique in a cadaveric multidirectional instability model.

BACKGROUND Commonly performed arthroscopic rotator interval closure techniques that imbricate the rotator interval in a superior-inferior direction have been unable to reproduce the stabilizing effects of an open medial-lateral rotator interval imbrication. HYPOTHESIS The medial-lateral rotator interval closure will allow less inferior and posterior glenohumeral translation than the superior-inferior rotator interval closure, and the medial-lateral rotator interval closure will result in less loss of external rotation than the superior-inferior closure. STUDY DESIGN Controlled laboratory study. METHODS Eight match-paired cadaveric shoulders were stretched to 10% beyond the maximum range of motion in 0 degrees and 60 degrees of glenohumeral abduction to create a multidirectional instability model. Shoulders were then repaired using a superior-inferior rotator interval closure or an arthroscopic medial-lateral rotator interval closure with an anchor in the humeral head. Rotational range of motion, glenohumeral translation, and humeral head apex position were measured for intact, stretched, and repaired conditions in both 0 degrees and 60 degrees of glenohumeral abduction. RESULTS In 0 degrees of abduction, after both rotator interval closure techniques, external rotation decreased significantly (by 4.4%; P < .05) relative to the stretched state and was restored to the intact state. In 60 degrees of abduction, only the medial-lateral rotator interval closure restored range of motion to the intact state. In 60 degrees of abduction, the medial-lateral rotator interval closure was more effective in reducing posterior translation than was the superior-inferior closure (P = .03). CONCLUSION The medial-lateral rotator interval closure restored range of motion to the intact state better than the superior-inferior closure. Compared with the superior-inferior rotator interval closure, the medial-lateral closure significantly decreased posterior translation with the shoulder in abduction and external rotation. CLINICAL RELEVANCE Arthroscopic medial-lateral rotator interval closure with a suture anchor in the humeral head can be considered in the surgical treatment of patients with multidirectional instability, especially those with a component of posterior instability, without concern for excessive loss of range of motion.