The effects of immobilisation and exercise on tendon healing

Methods: 32 rats were randomised into: (1) sham operated (sldn incision only), (2) division only (surgical transection of the Achilles tendon), (3) "dummy" ex-fix (Achilles tendon division and K-wires through the femur, proximal tibia, calcaneus and metatarsals), (4) rigid exf i x (K-wires fixed by two triangular frames). 20 rats were randomised into: ( 1 ) normal cage activity group, (2) exercise group (15 min/day swimming). Functional recovery was evaluated in an objective blinded fashion from hind paw prints (the Achilles Functional Index: AFI). The mechanical properties of the healing Achilles tendon constructs were evaluated on day 15.