Prevention of restrictive adhesions in primary tendon repair by HA-membrane: experimental research in chickens.

Hyaluronic acid (HA) is a glycosaminoglycan polymer that has been found to have some beneficial effects on the prevention of adhesions in primary tendon repairs. The need for slow elimination preparations of HA has been identified. We have combined HA and carboxymethylcellulose (CMC) in order to get a slow elimination preparation of HA and studied its possible effect on primary tendon healing. A gel form of NaHe (19 mg/ml; mw: 6.5 x 10(6)) was mixed with Na CMC (degree of substitution: 0.8) under sterile conditions. A jelly like mixture was thinned and HA membrane was achieved after drying in the refrigerator. The right legs of Leghorn chickens (n = 30) were prepared under IM ketamine anaesthesia by making partial cuts (75%) of flexor profundus tendons at zone II in the second, third and fourth toes, and repaired using a modified Kessler type suture (5/0 nylon). HA-membranes were applied around the repair sites in the third toes while 0.5 ml of hyaluronic acid and saline were poured on to the repair sites in the second and fourth toes, respectively. Skin incisions were closed and the legs were splinted for 15 days. Biomechanical and histological controls were made at the first, second and third postoperative months. No wound dehiscence or exposure of repaired tendons was observed on the operated toes. After collection of samples by amputation at MP levels, two-phalanx free biomechanical assessment was done. The calculated peaks of differential joint motion were very similar to the corresponding non-operated contralateral toes in the HA-membrane treated group. The toe tip displacement curves also resembled the non-operated ones in this group. HA membrane was detected as blue particles on specimens taken at the 30th day following surgery. There were few adhesions in this group microscopically at the third month. Adhesions were similar in the HA treated group while dense adhesions were seen in the saline treated group. These findings suggest that HA membrane acting as a physicochemical barrier can prevent restrictive adhesions in primary tendon repairs.