Comparison of mediolateral (V-shaped) vs. anteroposterior dominant rotator cuff tears: the anteroposterior tear width contributes more to postoperative retears than mediolateral length when the tear size area is similar.

Background: Tear size is a significant prognostic factor following rotator cuff repair. However, no study has investigated which dimension of the tear, the mediolateral (ML) or anteroposterior (AP), more significantly influences the outcome when the product of the 2 dimensions, the tear size area, is similar.

Methods: A retrospective cohort study was conducted with patients who underwent arthroscopic full-thickness rotator cuff tear (FTRCT) repair. Two contrasting groups were derived from preoperative tear dimensions. The ML dominant (MLD) group consisted of 45 FTRCTs with the ML tear dimension at least 1.5 times larger than the AP, and retraction exceeding the humeral head apex. The AP dominant (APD) group included 35 FTRCTs with an inverse proportion of the dimensions and retraction short of the humeral head apex. Demographic data, preoperative and postoperative magnetic resonance imaging, clinical scores, and strength were compared between the groups.

Results: The mean follow-up was 26.7 and 32.2 months in the MLD and APD groups, respectively. The tear size in area (MLD vs. APD, 521.0 vs. 523.4 mm, P = .960) and the discrepancy between ML and AP dimensions (2.0 vs. 1.9, P = .597) were similar. However, the MLD group demonstrated significant female predominance (P = .003), dominant arm involvement (P = .007), a higher incidence of pathologic subacromial spurs (P = .016), narrower acromiohumeral distance (P < .001), shorter residual tendon (P < .001), and advanced supraspinatus muscle atrophy (P = .005). Other baseline parameters were comparable between the groups. At the 1-year postoperative magnetic resonance imaging, the MLD group demonstrated a significantly lower retear rate (4.4% vs. 31.4%, P = .001). Nevertheless, clinical scores and strength at the last follow-up did not significantly differ.

Conclusion: In a similar tear size area, the greater AP width contributes more than the ML length in causing a retear. Female predominance, dominant arm involvement, subacromial spurs, shorter residual tendon, and supraspinatus muscle atrophy were more demonstrated in MLD tears. Surgeons should be aware that healing may be poor in APD tears despite less retraction.