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 tend on repairs. The need for slow elimination preparations of HA has been ident ified. We have combined HA and carboxymethylcellulose (CMC) in order to get a slow elimination preparation of HA and studied its possible effect on pr imary tendon healing. A gel form of NaHe (19 mg/ml; mw: 6.5 x 10(6)) was mixed with Na CMC (degre e 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 ana esthesia by making partial cuts (75%) of flexor profundus tendons at zone I I in the second, third and fourth toes, and repaired using a modified Kessl er type suture (5/0 nylon). HA-membranes were applied around the repair sit es 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 i ncisions were closed and the legs were splinted for 15 days. Biomechanical and histological controls were made at the first, second and third postoper ative months. No wound dehiscence or exposure of repaired tendons was observed on the ope rated toes. After collection of samples by amputation at MP levels, two-pha lanx free biomechanical assessment was done. The calculated peaks of differ ential joint motion were very similar to the corresponding non-operated con tralateral 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 sur gery. There were few adhesions in this group microscopically at the third m onth. 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.