A new model for experimental tendon adhesions in the chicken

A minimally invasive model using a manual abrader to induce adhesions in the chicken's central digit is described. The flexor synovial sheath and the profundus tendon were abraded with access through small flaps at the level of the proximal and distal phalanges of the avian long toes. The birds were divided into two groups according to the severity of the induced trauma. Group I birds received an abrasion injury and were euthanized to allow biomechanical testing 5 weeks postoperatively. Group II birds had a more severe abrasion and were euthanized similarly and tested 5 weeks after surgery. Results were compared with nonsurgical controls. Long toe function was evaluated weekly by measuring (1) the range of active flexion of each interphalangeal joint, resolved to total angular range; (2) the grasping ability on graded-diameter perches; and (3) the flexion deficit of the long toe. Postmortem biomechanical properties of the adhesions were measured. There was a significant difference between the unoperated controls and abraded digits of both groups in all parameters (p < 0.001). There was, in addition, a marked change in most of the measured parameters between groups I and II. In group I digits the functional and biomechanical deficit was less than group II. In summary, this animal model of long-segment abrasive injury to the tendon and sheath is a simple and reproducible method to generate adhesions and can be used for the evaluation of treatment modalities for adhesion prevention.