Evaluation of Success of Transport Disc Distraction Osteogenesis and Costochondral Graft for Ramus Condyle Unit Reconstruction in Pediatric Temporomandibular Joint Ankylosis

Abstract

The costochondral graft (CCG) is considered the reference standard for pediatric temporomandibular joint reconstruction. It has the disadvantages of unpredictable growth, donor site morbidity, and the need for intermaxillary fixation. It has been reported that transport disk distraction osteogenesis (TDDO) can result in the formation of a neocondyle and disc. We performed a randomized trial to measure and compare clinically relevant outcomes of ramus-condyle unit (RCU) reconstruction using CCG and TDDO for pediatric temporomandibular joint ankylosis (TMJA). In the present randomized controlled trial (block randomization with a variable block size), pediatric patients with unilateral, nonrecurrent TMJA aged 3 to 16years who had presented to our unit from December 2015 to June 2017 were enrolled. Instead of temporalis myofascial flap interposition, a buccal fat pad was used to fill the gap created by osteoarthrectomy. The primary outcome parameter was mouth opening. A mouth opening of at least 25mm at the median follow-up point was considered success. The secondary outcome parameters were occlusion, laterotrusion, protrusion, reankylosis, neocondyle, chin deviation, facial asymmetry, midline shift, and neo-disc formation. Data were analyzed using the independent t test and rank sum test. A total of 24 patients were enrolled in the CCG and TDDO groups (n=12 in each group). Trauma (40.9%) was the most common etiology with a slight male preponderance (59.09%). The mean age was 10.32±2.85years. The average distraction achieved in the TDDO group was 10.42mm. The median follow-up duration was 31.5months (range, 24 to 39months). The mean preoperative maximal incisal opening had improved from 8.5±4.1 and 9.5±7.1mm in the CCG and TDDO groups preoperatively to 35.7±2.7 and 34.4±8.9mm, respectively, at the median follow-up point (P<.005). RCU reconstruction with both modalities resulted in improvement in all the parameters; however, the intergroup comparison showed statistically non-significant differences. No reankylosis or open bite was found. The 3-hour delayed gadolinium-enhanced magnetic resonance imaging scan showed successful neo-disc formation. Similar success can be achieved in RCU reconstruction using either CCG or TDDO for pediatric TMJA. Both techniques have some advantages and disadvantages. RCU reconstruction using CCG or TDDO results in formation of a neocondyle, maintenance of occlusion, and correction of facial asymmetry.