Biomechanical analysis of intrinsic tendon healing in vitro and the effects of vitamins A and E.

This in vitro study was designed to test the hypothesis that flexor tendons have an intrinsic capability to heal as judged by rigorously defined biomechanical criteria. Rabbit forepaw flexor tendons (n = 114) were transected and repaired in zone II and cultured in standard media or media supplemented with vitamin A or E. Tenorrhaphies were disrupted at 0, 2, 8, and 12 weeks after repair by fixed-speed tensiometry. The following parameters were calculated: true stress, true strain, and normalized energy absorption. Statistical analysis was by Student's t test. Peak stress (strength) increased equally in all groups over time (p less than 0.05), while normalized energy absorption (toughness) was markedly higher in the vitamin E-treated group after 2 weeks' incubation (p less than 0.05). These data represent the first biomechanical evidence of intrinsic tendon healing in vitro. Biomechanical methodology and vitamin effects are discussed in detail.