Effect of poly-DL-lactide resorbable film on postoperative muscle adhesion of the knee joint in rabbits

AIM: Previously, the use of silica gel for knee joint is effective for reducing the muscle adhesion so as to prevent the stiffness of knee joint, but secondary operation is needed to fetch the film. This study was to observe the effect of anti-adhesion poly-DL-lactide (PDLLA) resorbable film on reducing the muscle adhesion of knee joint. METHODS: The experiment was accomplished in the animal laboratory in the Third People's Hospital Affiliated to College of Medicine, Shanghai Jiao Tong University between March and August in 2006. Thirty New Zealand adult male rabbits were randomly separated into treatment group and control group, each containing 15 animals. In the treatment group, the lamellar muscles and most of the synovium at femoral rectal muscle close to the whirbone were removed through a medial incision of left knee joint in rabbits, and then were impaired. An anti-adhesion PDLLA resorbable film with suitable size (0.8 cm×1.2 cm) was placed at the impaired part. After that, the rabbit knee joint was fixed at 90° with cast for three weeks, the observation persisted until eight weeks later when all the rabbits were sacrificed under anesthesia. In the control group, the anti-adhesion membrane was not placed. Before impairment, three weeks and eight weeks after impairment, the passive flexion angles of knee joint were tested. The local adhesion of knee joint, pathological changes of tissue surrounding the muscle, and the absorption of anti-adhesion membrane were all detected eight weeks later. RESULTS: ①Eight weeks later, the severe adhesion of tissue nearby the knee joint was detectable in the control group, showing dense fibrils and limitations on passive activity of knee joint. In the treatment group, the adhesion was lighter and no stiffness was found.②Major thick and dense collagen fibers formed in the control group 8 weeks later, and the adhesion occurred in the cortical bone or muscular tissue. While the collagen fibers arrayed loosely and rarely in the treatment group, without the presence of compact adhesion.③Three and eight weeks after impairment, the flexion angles in the treatment group was significantly less than those in the control group (P < 0.01). And the angles in both groups were also significantly reduced 8 weeks later compared with 3 weeks later (P < 0.01). CONCLUSION: The application of PDLLA anti-adhesion resorbable film can make some effects on reducing adhesion and preventing stiffness of joint after impairment of muscle.