Long-term follow-up after arthroplasty for pediatric temporomandibular joint ankylosis performed before the critical period of mandibular growth: A case report

INTRODUCTION AND IMPORTANCE: Pediatric temporomandibular joint (TMJ) ankylosis can lead to significant difficulties in opening the mouth, as well as stunted mandibular growth resulting in a small mandible and facial asymmetry. For pediatric TMJ ankylosis, the ideal time to perform TMJ mobilization in order to achieve standard mandibular growth is unclear. CASE PRESENTATION: An 11-year-old boy with limited mouth opening was referred to our hospital. The patient had previously sustained a fracture of the left articular process of the mandible. Clinical examination revealed bony ankylosis of the left TMJ, and the condylar head was dislocated anteromedially. The bony ankylosis was removed at the age of 12 years. Mouth-opening exercises were started postoperatively. His mouth opening recovered without the development of severe facial asymmetry, and the dislocated condylar process served as a new joint and provided good jaw function until the most recent follow-up at the age of 21 years. CLINICAL DISCUSSION: It is practical to perform surgical intervention after the child has achieved some growth and at a time when the surgery would not interfere with jaw development because the mouth opening can be improved by postoperative physical therapy. No interpositional implant was used because strict postoperative mouth opening exercises and the displaced condylar process, which was maintained to almost normal TMJ structure, were expected to preserve the gap between the ramus and the zygomatic arch. CONCLUSION: Surgical intervention in the appropriate growth period is important to prevent the sequelae of mandibular growth suppression due to pediatric TMJ ankylosis.