Does Lateral Pterygoid Muscle Reattach After Ramus-Condyle Unit Reconstruction in Temporomandibular Joint Ankylosis Patients?

BACKGROUND

The removal of ankylotic bone requires detachment of lateral pterygoid muscle (LPM) from the ankylosed condyle. Whether spontaneous reattachment of LPM occurs or not following autogenous ramus-condyle unit (RCU) reconstruction in temporomandibular joint ankylosis (TMJA) is not yet known.

PURPOSE: The study purpose was to measure and compare the incidence of spontaneous LPM reattachment following 2 RCU reconstruction techniques-costochondral graft (CCG) and transport disc distraction osteogenesis (TDDO) and its implications on postoperative jaw motion.

STUDY DESIGN, SETTING, SAMPLE: A double-blind randomized clinical trial was implemented. Pediatric TMJA patients aged 3 to 16 years who consented for ankylosis release and RCU reconstruction were included. Patients were excluded if they had diagnosis other than TMJA, had bilateral/recurrent TMJA, underwent RCU reconstruction using modality other than CCG or TDDO, or did not give consent to come for follow-up/participate in this study.

PREDICTOR VARIABLE: The primary predictor variable was the RCU reconstruction method (CCG or TDDO).

OUTCOME VARIABLE: Primary outcome variables included the presence (yes/no) and anatomical site of LPM reattachment. Secondary outcomes were anatomic (reconstituted condyle formed, volume of LPM, temporalis muscle reattachment and its site) and functional (laterotrusion and maximal interincisal opening).

COVARIATES: The covariates included demographics (age, sex) and perioperative (ankylosis classification, etiology, magnetic resonance imaging evaluation time).

ANALYSES: Nonparametric continuous variables were analyzed using the Wilcoxon rank-sum test, categorical variables with the χ2 test, and within-group comparisons using the signed-rank test. A P value <.05 was considered statistically significant.

RESULTS

The study sample had 12 subjects (median age = 11.5 years (interquartile range (IQR) = 4.5); M:F = 7:5). RCU reconstruction was done with CCG (n = 5 (41.7%)) or TDDO (n = 7 (58.3%)). On magnetic resonance imaging evaluation at median 237 days, the LPM (n = 12/12,100%) and temporalis muscles (n = 11/11,100%) showed spontaneous reattachment. Different sites of LPM reattachment were noticed, ie, on reconstituted condyle neck [n = 3 (25%),CCG = 1 (20%),TDDO = 2 (28.6%)], on reconstituted condyle head [n = 4 (33.3%),CCG = 1 (20%),TDDO = 3 (42.9%); no resorption], and on ramal cut surface [n = 5 (41.7%),CCG = 3 (60%),TDDO = 2 (28.6%) (P = .8)], with lower ipsilateral side volume. At 3 years follow-up, an improvement in median maximal interincisal opening (Preoperative = 9.5 mm (IQR = 2.5),Follow-up = 35 mm (IQR = 6), (P = .002)) and laterotrusion (Ipsilateral:Preoperative = 3 mm (IQR = 10),Follow-up = 10 mm (IQR = 5), (P = .9); Contralateral:Preoperative:0 mm (IQR = 0),Follow-up = 2 mm (IQR = 5), (P = .01)) were noted.

CONCLUSION AND RELEVANCE: LPM showed spontaneous reattachment and resulted in improved laterotrusion. The site of reattachment has a role in reconstituted condyle and coronoid remodeling.