(64) Does the Lateral Pterygoid Muscle Reattach After Autogenous Ramus-Condyle Unit Reconstruction in Temporomandibular Joint Ankylosis Patients?

Abstract: Statements of the problem: The Kaban, Bouchard, and Troulis protocol is used for successful treatment of temporomandibular joint (TMJ) ankylosis. However, it is not known as to what happens to detached lateral pterygoid (LPM) and temporalis muscles (TM) after osteoarthrectomy and coronoidectomy (if done). The study aimed to evaluate the fate of LPM and TM, 6 months post TMJ ankylosis release and autogenous reconstruction using costochondral graft (CCG)/ transport disc distraction osteogenesis (TDDO). Materials and methods: A prospective study was implemented. The study sample consisted of TMJ ankylosis patients who gave consent for ramus-condyle unit (RCU) reconstruction with CCG/TDDO and agreed for MRI at 6-month follow-up. The primary outcome variable was LPM reattachment and its site. The secondary outcome parameters were neocondyle formed, temporalis reattachment, and its site, volume of LPM, laterotrusion and maximal incisal opening. Demographic variables (patient’s age at the time of surgery, gender) were also recorded.Method of data analysis, including as appropriate:-Sample size: The study sample had 12 subjects (mean age = 11 ± 3 years; M:F = 7:5).-Duration of study:Patients were followed up for 3 years.-Statistical methods:Quantitative data following normal and skewed distribution were compared by using independent t-test and rank-sum test respectively. P < .05 was considered statistically significant.-If subjective analysis, so stateResults of investigation: RCU reconstruction was done with CCG (n = 5) or TDDO (n = 7). Outcomes data:On MRI evaluation, the LPM and temporalis muscles showed reattachment at variable sites. Neocondyle formation was noticed on CBCT. A significant improvement in the mean MIO was noted from 9±4.8 mm preoperatively to 34.4 ± 6.09 mm at the follow-up (P < .01). The median ipsilateral and contralateral laterotrusion increased from 3 (0-13) to 10 (0-13) mm and 0 (0-7) to 2 (0-10) mm respectively.

Conclusions: LPM and temporalis showed spontaneous reattachment. The site of reattachment has a role in neocondyle and coronoid remodeling. However, a larger sample size and longer follow-up would provide a better evaluation of the role of muscle reattachment on bony regeneration/growth.References1. Kaban, Bouchard, Troulis. A protocol for management of temporomandibular joint ankylosis in children. J Oral Maxillofac Surg. 2009;67(9):1966-1978.2. Singh A, Roychoudhury A, Bhutia O, Yadav R, Bhatia R, Yadav P. Longitudinal changes in electromyographic activity of masseter and anterior temporalis muscles before and after alloplastic total joint replacement in patients with temporomandibular ankylosis: a prospective study. Br J Oral Maxillofac Surg. 2022;60(7):896-903. doi:10.1016/j.bjoms.2022.01.009

Follow-up MRI of Patient 1 (right TMJ ankylosis in which RCU reconstruction was done with CCG) shows lateral pterygoid reattachment at the medial slant of neocondyle.
Follow-up MRI of Patient 3 (right TMJ ankylosis in which RCU reconstruction was planned with TDDO, but patient did not come for distractor activation after 1.5 mm) shows lateral pterygoid reattachment at the tip of remodeled neocondyle
Table: Outcome variables of the study (n=12).