Remnant Tendon Preservation Enhances Rotator Cuff Healing: Remnant Preserving Versus Removal in a Rabbit Model

Purpose To assess whether anatomic repair preserving remnant tendon tissue can enhance tendon‐to‐bone healing biomechanically and histologically in a rabbit rotator cuff tear model. Methods In this controlled laboratory study, bilateral infraspinatus tenotomy from the greater tuberosity, with remnant tendon on the footprint, was performed in 26 New Zealand white rabbits. An open transosseous technique was used to perform bilateral infraspinatus tendon repair 1 week later. Preservation and removal of the remaining tendon were performed on the left and right sides, respectively. Seven rabbits each were killed humanely for biomechanical testing and 6 rabbits each were killed humanely for histologic evaluation at 4 and 12 weeks. Results Significantly superior biomechanical properties were shown in the remnant tissue–preservation group at 4 and 12 weeks in terms of maximum load (89.6 ± 24.3 N vs 68.2 ± 20.7 N at 4 weeks, P  = .048; 120.8 ± 27.5 N vs 93.3 ± 25.1 N at 12 weeks, P  = .035) and stiffness (25.3 ± 3.4 N/mm vs 17.7 ± 5.2 N/mm at 4 weeks, P  = .009; 26.7 ± 5.2 N/mm vs 19.4 ± 5.2 N/mm at 12 weeks, P < .001). Improved bone‐tendon interface histologic maturity scores (14.8 ± 0.9 vs 8.2 ± 1.5 at 4 weeks, P  = .027; 16.8 ± 0.7 vs 10.5 ± 1.4 at 12 weeks, P  = .027) and large metachromasia areas (0.117 ± 0.053 mm 2 vs 0.032 ± 0.017 mm 2 at 4 weeks, P  = .022; 0.14 ± 0.046 mm 2 vs 0.037 ± 0.016 mm 2 at 12 weeks, P  = .007) were obtained in the preservation group compared with the removal group at 4 and 12 weeks. Conclusions This study showed that preserving remnant tissue in anatomic repair can significantly improve rotator cuff healing compared with remnant tissue removal on the footprint in terms of biomechanical properties, bone‐tendon interface histologic maturity scores, and metachromasia at 4 and 12 weeks after repair in a rabbit rotator cuff tear model. Clinical Relevance The results suggest that preservation of remnant tissue on the footprint containing the native bone‐tendon interface, when present, may be a better option for rotator cuff healing in rotator cuff repair surgery.