Comparison of Temporomandibular Joint Reconstruction With Custom (TMJ Concepts) Vs. Stock (Biomet) Prostheses

Comparison of Temporomandibular Joint Reconstruction with Custom (TMJ Concepts) vs. Stock (Biomet) Prostheses

Matt Zieman, Stuart McKenzie, DMD, MD and Patrick J Louis, DDS, MD

The prostheses used today for alloplastic replacement of the temporomandibular joint (TMJ) were just recently developed over the last two decades. Currently, there is limited research on the efficacy of TMJ prosthetic systems when compared to each other. This study aims to compare the differences in maximal incisal opening (MIO) and pain levels in patients treated with custom TMJ prostheses made by TMJ Concepts and stock prostheses made by Biomet.

            This retrospective review analyzed 36 patients that were treated with complete TMJ reconstruction at the University of Alabama at Birmingham from 2005-2012. IRB approval for the review was obtained prior to starting. Only patients with recorded measurements for MIO and pain both before and after surgery were included in this study. Also, any patient that had previously been treated with TMJ replacement was excluded due to the relatively poorer outcomes seen in patients with 2 or more TMJ replacements.¹ The difference in MIO measurements and pain scores from pre-surgery to the last follow-up visit were compared for each patient treated with the TMJ Concepts and Biomet systems. The data was analyzed using standard mean and range calculations, and the two systems were compared using a two-tailed t-test with unequal variance.

            Of the 36 patients, 30 were female (83.3%) and 6 were male. Twenty patients were treated with the Biomet TMJ replacement system (55.5%) and 16 with the TMJ Concepts system. The average age of the patients was 47 (range 29-70 years old) and the average time from date of surgery to last follow-up was 2.83 years for the TMJ Concepts group and 2.65 years for the Biomet group.  In regards to MIO, there was a slight increase (2.56mm) within the TMJ Concepts group when comparing pre-surgery and last follow-up measurements. Within the Biomet system, there was a slight decrease (-0.85 mm) in MIO measurement before and after surgery. Neither group showed a significant difference in MIO when compared within each system nor was there a significant difference in MIO between the two systems before and after treatment. In regards to pain, there was a significant decrease (-4.75) between pre-surgical pain and pain recorded at the last follow-up within the TMJ Concepts system. Within the Biomet system, there was no statistically significant decrease in pain score (-3.30) despite the heavy trend in pain reduction. Also, there was no significant decrease in pain reduction between the two replacement systems reviewed in this study.

            Severe degeneration of the TMJ resulting in pain and loss of function are frequent indications for total joint replacement. Early prostheses used for TMJ replacement frequently resulted in postoperative complications including severe pain, condylar resorption, and foreign body reactions among other problems. The newer systems have been extensively researched and have shown to have better success, yet there is little in the literature comparing custom vs. stock prostheses. ^1,2 Within the limitations of this study, it has been shown that there is no significant difference in MIO and pain scores after total joint replacement with a custom manufactured prosthesis compared to a stock prosthesis.

References:

¹Wolford LM, Mehra P. Custom-made total joint prostheses for temporomandibular joint reconstruction. Proc (Bayl Univ Med Cent). 2000;13(2):135-138.

²Lee SH, Ryu DJ, Kin HS, et al. Alloplastic total temporomandibular joint replacement using stock prosthesis: a one-year follow-up report of two cases.