Total joint replacement of the temporomandibular joint (TJR) can be associated with intraoperative and postoperative complications. We report herein the occurrence of a postoperative open bite malocclusion, the result of condylar hyperplasia affecting the non-operated joint at 1 year after unilateral total joint replacement.
Enhanced growth resembling activity of the condyle, accompanied by facial asymmetry, can be found in hemimandibular or condylar hyperplasia, even in adulthood.
Condylar hyperplasia is a postnatal growth abnormality, characterized by excessive unilateral growth resembling activity of the mandibular condyle, which results in facial asymmetry and bite defects. The disorder develops as a consequence of accelerated growth in adolescents, or due to its prolongation in adult patients. The disorder most commonly involves those aged between 10 and 30 years, with males and females equally affected (ratio 1:1). While the exact aetiology is unknown, genetic and hormone disorders contribute to its development, as well as trauma; it may develop in response to excessive stress on the condyle or an infection.
Clinical symptoms include facial asymmetry, and depending on the growth dynamics, various bite defects. These bite defects can be divided into two groups. The first comprises an open bite with an angular shift of the mandible and elongation of the mandibular arm on the affected side, chin centre deviation towards the affected side, and the development of a unilateral open bite on the same side; this is seen with vertical growth. The second involves the centre of the mandible and biting point shifting towards the unaffected side, resulting in cross bite; this is seen with rotational growth.
In condylar hyperplasia, the symptoms typical of temporomandibular joint (TMJ) involvement, i.e. sound phenomena, restricted mobility, and pain, are infrequent. In addition to clinical examination, the diagnosis of this condition also requires an X-ray image (which can confirm the skeletal abnormality) and a scintigraphy image; scintigraphy makes it possible to distinguish the active form of hyperplasia from the passive form. This then determines the type of treatment. For the active form, i.e. with continued growth activity, the primary treatment includes a high condylectomy (condylar shaving) during which up to 5 mm of cartilage and bone are shaved off the top of the condyle; this inhibits condylar growth. For the passive form, the only option is orthognathic and orthodontic correction of the mandibular abnormality.
We report the case of a 41-year-old male who was without systemic disease. At the age of 15 years he suffered a fracture of the left condyle. Following conservative treatment, ankylosis gradually developed in his left TMJ. At age 19 years he underwent open surgery for gap arthroplasty. In the course of the first postoperative year, the condition relapsed with restricted mandibular mobility. At the age of 41 years, the patient attended for examination due to mandibular mobility restricted to 11 mm (inter-incisal). In view of the fibro-osseous ankylosis in the left TMJ, resection of the ankylotic block was planned with subsequent total joint replacement.
The patient underwent the planned surgery, which involved resection of the ankylotic bone block, followed by joint replacement with a stock prosthesis (Biomet Inc., Jacksonville, FL, USA). The correct position of the jaws was secured by rigid intermaxillary fixation, which was removed on completion of the surgery. Following surgery, the patient confirmed a significantly improved condition; at 1 month postoperative he was able to open his mouth to 29 mm with deviation towards the left (the operated side).
At a check-up 12 months postoperative (February 2011), the patient indicated a shift of the mandible towards the left operated side and a modified bite. Objectively, the mandibular centre was shifted towards the operated side (with the bite point shifted by 5 mm); facial asymmetry due to the chin shift was observed. The inter-incisal mouth opening was recorded at 44 mm. The patient was X-rayed for a suspected implant failure. Implant failure was not demonstrated, however there was a change in shape of the condyle on the right side compared to the postoperative image; hyperplasia of the condyle was noted. Skeletal scintigraphy confirmed heightened osseous alteration of the right TMJ, i.e. on the non-operated side ( Fig. 1 ). Computed tomography (CT) images clearly showed advanced condylar hyperplasia on the right side ( Figs 2 and 3 ).
Over the course of the next 2 months, the growth continued to progress and the lower mandible shifted further to the left – the shift of the incisal point of the lower mandible was measured as 11 mm. For this reason, a high condylectomy was performed (condylar shaving), removing 5 mm of the right condyle and stopping the pathological growth (May 2011). Histopathological investigations showed a significant increase in hyperplastic cartilage, which had broadened the subchondral layer of bone. Osteochondroma and other tumours were excluded.
At the present time, 35 months after this last operation, the patient’s condition is stable, without any signs of further growth progression ( Fig. 4 ).