Delamination rates of tissue flaps used in articular cartilage repair.

A popular strategy in the treatment of articular cartilage lesions involves the introduction of cell suspensions into the defect void and its closure with a periosteal flap (autologous chondrocyte transplantation technique). We applied this methodology in goats and discovered that all sutured flaps (n = 6 animals) became detached from nonimmobilized joints during the recovery period. The purpose of this study was to ascertain whether postoperative restriction of joint movement could prevent the delamination of flaps. Partial-thickness defects were created in the knee joint cartilage of 27 goats. These defects were then filled with a fibrin matrix and covered with periosteal (n = 6) or fascial (n = 21) flaps, which were sutured with simple, interrupted stitches to the surrounding tissue. The joints were immobilized by means of a modified Robert Jones bandage for periods of 2-6 weeks, after which time they were inspected for the absence or presence of flaps. In four animals, joint immobilization for 3 weeks was followed by free movement for a similar period. Four of the six periosteal flaps and two of the 21 fascial ones became delaminated after the period of immobilization. In the four goats permitted 3 weeks of free joint movement following a similar period of joint immobilization, all flaps (which had been retained up to the end of the immobilization period) became detached. These findings indicate that joint immobilization hinders the delamination of flaps but that this restriction of movement must be sustained for an undefined period of time. The nature of the tissue used for flaps also influences their rate of retention by immobilized joints.