Extracellular matrix as an inductive template for temporomandibular joint meniscus reconstruction: a pilot study

Purpose: A device consisting of powdered porcine urinary bladder extracellular matrix (UBM-ECM) encapsulated within sheets of the same material was investigated as a scaffold for temporomandibular joint (TMJ) meniscus reconstruction.

Materials and methods: Five dogs underwent unilateral resection of the native meniscus and replacement with a UBM-ECM device. Necropsies were performed at 3, 4, 8, 12, and 24 weeks. Two additional dogs underwent bilateral resection of the meniscus with replacement with a UBM-ECM device on 1 side, leaving the contralateral side empty as a control. Necropsies were performed at 24 weeks for bilaterally treated animals.

Results: Macroscopically, the UBM-ECM implants were remodeled rapidly and were indistinguishable from newly deposited host tissue at all time points. Microscopically, remodeling was characterized by a dense infiltration of predominantly CD68(+) mononuclear cells and smooth muscle actin-positive fibroblast-like cells at early time points changing with time to a sparse population of smooth muscle actin-negative spindle-shaped cells resembling those of the native fibrocartilaginous TMJ meniscus. Furthermore, the remodeling process showed deposition of predominantly type I collagen, the density and organization of which resembled those of the native meniscus by the 24-week time point. Ingrowth of calsequestrin-positive skeletal muscle tissue was also observed at the periphery of the remodeled UBM-ECM device and was similar to that found at the attachment site of the native meniscus to the surrounding soft tissues. Histologic results were identical for samples excised from both unilaterally and bilaterally treated animals. No adverse changes in the articulating surfaces of the condyle or fossa were observed in UBM-ECM-implanted joints. In the bilaterally treated animals, the unimplanted control side was characterized by degeneration and pitting of the articulating surfaces of both the condyle and the fossa, with disorganized bands of fibrous connective tissue observed within the joint space.

Conclusion: Results of this study suggest that the UBM-ECM device provides an effective interpositional material while serving as an inductive template for reconstruction of the TMJ meniscus.