Biomechanical and histological analysis after tenotomy of the long head of the biceps in the rabbit shoulder model.

Tenotomy of the long head of the biceps tendon (LHBT) is gaining popularity in shoulder surgery. We evaluated biomechanical and histological changes after tenotomy in a rabbit LHBT tenotomy model to confirm that autotenodesis is a phenomenon that occurs after the procedure. Twenty-three rabbits were included. The right shoulder was harvested from 10 randomly selected rabbits. The shoulders were tested to determine the pullout strength of LHBT at the bicipital groove immediately after being tenotomized. The left shoulder of three of these rabbits also underwent histological analysis. The other 13 rabbits underwent LHBT tenotomy (tenotomy model). Six weeks post-operatively, 10 were assigned for biomechanical study, and three underwent histological analysis. The pullout strength and histology were compared with the immediate post-tenotomy data. The pullout strength of the immediate post-tenotomy (5.53 ± 2.22 N) was significantly (p < 0.001) less than the pullout strength of the 6 weeks post-tenotomy model (44.07 ± 7.75 N). On histological analysis, marked fibrosis was noted around the LHBT at the bicipital groove in the 6 weeks post-tenotomy model. Adhesion of the LHBT at the bicipital groove after tenotomy, which is called "autotenodesis," is a definite phenomenon that could help the tendon resist distal migration of the LHBT after tenotomy. These results support execution of biceps tenotomy in shoulder surgery.