TEMPOROMANDIBULAR-JOINT DISC REPLACEMENT MADE BY TISSUE-ENGINEERED GROWTH OF CARTILAGE

Objective: To test the effectiveness of the new technique of tissue-en gineered growth of cartilage, temporomandibular joint (TMJ) disc repla cements were created by seeding dissociated chondrocytes on synthetic, three-dimensional, bioresorbable polymer constructs of a predetermine d anatomic shape, incubating the cell-polymer constructs in vitro, and transplanting them into test animals. Materials and Methods: Twelve h ighly porous and bioresorbable cell-transplantation devices in the sha pe of TMJ discs were created using biodegradable polylactid and polygl ycolic acid fibers. Bovine articular cartilage was dissociated into ch ondrocytes and the cells were allowed to attach to the three-dimension al polymer scaffolds and multiply in vitro. After 1 week, the cell-pol ymer constructs were implanted subcutaneously into nude mice. The neoc artilage was assessed by magnetic resonance imaging (MRI) techniques, gross inspection, histology, and biomechanical and biochemical analysi s after 12 weeks. Results: All implants seeded with chondrocytes showe d gross evidence of histologically organized hyaline cartilage. The sc affolds maintained their specific shape. They not only showed appropri ate intrinsic stability during neomorphogenesis of cartilage in vitro and in vivo, but also seemed to guide the growth of cartilage. The pre sence of sulfated glycosaminoglycans was shown by aldehyde fuchsin alc ian blue staining of the specimens. Type II collagen, considered to be indicative of cartilage formation, was found in the specimens tested. MRI showed signal characteristics similar to those of hyaline cartila ge. Analysis of neocartilage force/displacement curves and aqueous pha se compliance using a closed compression chamber suggested that the ab ility of the constructs to resist deformation was similar to that of n ative donor cartilage. Conclusion: The technology of tissue-engineered growth of cartilage on individually designed scaffolds may have many applications not only in reconstructive surgery of the TMJ, but also i n craniomaxillofacial, plastic, and orthopedic surgery.