Histological evaluation of full thickness skin as an interpositional graft in the rabbit craniomandibular joint

The purpose of this study is to determine the histological fate of the full thickness skin graft when placed into the temporomandibular joint using a rabbit model.

Fourteen New Zealand white rabbits were used and divided into 3 groups. Two rabbits were used as controls (Group A) whereby a sham operation was undertaken with an incision made and immediately repaired without breaching the joint space of the left craniomandibular joint (CMJ). In 6 rabbits (Group B), the joint capsule of the left CMJ was surgically breached but the articular disc was preserved and the wound was repaired. The remaining 6 rabbits (Group C) also had the left CMJ surgically exposed with preservation of the articular disc and the interpositional placement of a full thickness skin graft that was taken from the skin of their necks. All grafts were placed above the articular disc and head of condyle in the superior joint space and firmly secured to the surrounding tissues with nonresorbable sutures. The rabbits were sacrificed at 1, 3, and 5 months after surgery and the left CMJs were histologically prepared and examined under light microscopy.

The condylar head in the regions where the disc was present appeared to closely resemble that of the control rabbits. However, where the disc was breached by inadvertent surgical trauma (Group B), the underlying condyle showed an irregular outline with increased fibrosis and a marked reduction in mature cartilage. In the subarticular bone there was increased osteoblast and osteoclast activity reflecting high bone activity indicative of a remodeling rather than a degenerative process. The interpositional skin grafts in all experimental animals (Group C) were found adjacent to the condyle on the lateral aspect rather than above the condylar head where it was originally sutured in place. Significant atrophy and reduction in the number and size of the skin appendages such as sweat glands and hair follicles was found within the grafted skin of all experimental animals (Group C) compared with normal skin. All the grafts showed evidence of epidermoid inclusion cysts.

The full thickness skin graft is not a suitable interpositional material for the TMJ because of the high risk of epidermoid cyst formation and the propensity for lateral displacement of the graft even when sutured into the appropriate intra-articular position.