Double-Layer Rotator Cuff Repair: Anatomic Reconstruction of the Superior Capsule and Rotator Cuff Improves Biomechanical Properties in Repairs of Delaminated Rotator Cuff Tears.

BACKGROUND: Delamination in rotator cuff tears has been identified as a prognostic factor for negative outcome after repair, with a reported prevalence between 38% and 88%. PURPOSE: To compare biomechanical properties of 3 repair techniques for delaminated rotator cuff tears. STUDY DESIGN: Controlled laboratory study. METHODS: Eighteen fresh-frozen cadaveric shoulders were used to evaluate rotator cuff footprint reconstruction, contact area and pressure, displacement under cyclical loading, and load to failure of 3 double-row repair configurations: double-row suture repair with medial row knots (medially knotted bridge, mkB); knotless double-row repair using suture tapes (knotless bridge, klB); and knotless double-row, double-layer-specific repair (double-layer, DL). Dynamic pressure sensors were used to assess contact patterns at the footprint region in 0°, 30°, and 60° of glenohumeral abduction and 5 rotational positions (0°, 30° of internal rotation, 30° of external rotation, 60° of internal rotation, 60° of external rotation). Optical markers were used to document whole tendon and individual layer displacement after rotator cuff repair under cyclical loading for 200 cycles (10 N to 100 N at 1 Hz). Specimens were then loaded monotonically to failure at a rate of 33 mm/min. RESULTS: Mean contact area and footprint restoration were highest in the DL group at 60° of glenohumeral abduction for all rotational positions (mkB mean ± SD, 195.4 ± 54.3 mm2, 66.7% ± 19.7%; klB, 250.6 ± 34.9 mm2, 76.2% ± 10.3%; DL, 318.4 ± 36.6 mm2, 109.1% ± 24.0%; P < .001). The double-layer-specific repair showed the least displacement under cyclical loading (mkB mean ± SD, 0.53 ± 0.18 mm; klB, 0.79 ± 0.37 mm; DL, 0.31 ± 0.24 mm; P = .029), most closely resembling the native tendon. Peak loads at failure were comparable between repair groups (mkB mean ± SD, 366.92 ± 70.59 N; klB, 280.05 ± 77.66 N; DL, 398.35 ± 109.04 N; P = .083). CONCLUSION: Anatomic restoration of the superior capsular and tendon insertion in delaminated rotator cuff tears with a double-layer-specific repair configuration demonstrated superior footprint restoration with increasing abduction, while providing construct displacement comparable to the native tendon under cyclical loading. Peak load at failure was comparable between repair constructs. CLINICAL RELEVANCE: The prevalence and clinical importance of delaminated rotator cuff tears have long been underestimated. Anatomically correct individual reconstruction of the superior capsule and rotator cuff could restore near-native biomechanics and potentially reduce the risk of rotator cuff repair failure.