Viability and Volumetric Analysis of Free Autogenous Dermis Fat Graft as Interpositional Material in TMJ Ankylosis: A Long-Term MRI Study.

Abstract

Dermis fat graft has shown good clinical results as an interpositional material in temporomandibular joint (TMJ) ankylosis and prevents heterogeneous calcification following gap arthroplasty. However, survival of the graft and volume retention is still debatable. The main purpose of our study was to assess the viability of the graft, tissues changes associated with the graft and volume retention using magnetic resonance imaging (MRI). Fifteen patients with TMJ ankylosis underwent gap arthroplasty followed by placement of abdominal dermis fat graft and were randomly divided into two groups. Group 1 was subjected to MRI analysis of the graft at 3-6 months and Group 2 was analyzed at 1-2 years post-operatively. The graft was evaluated using T1- and T2-weighed images along with fat suppression (FS) sequences in all the three planes and the volume was also calculated. Both Group 1 (7 patients and 11 joints) and Group 2 (8 patients and 13 joints) showed the presence of viable fat on T1 and T2 images, confirmed by FS images. Minor tissue changes were observed at the center of the graft in 5 patients of Group 1 and 3 patients of Group 2. Average volume of the graft was 4.154 cm3 at 3-6 months and 4.269 cm3 at 1-2 years, respectively, and when compared to the original volume of the graft (4.583 cm3 in Group 1 and 4.712 cm3 in Group 2), the difference was statistically insignificant (p > 0.005). MRI shows long-term survival of autogenous dermis fat graft without significant volumetric reduction. This along with positive clinical results make dermis fat an excellent choice as an interpositional material for TMJ ankylosis.