Ankylosis of the temporomandibular joint

True ankylosis of the temporo-mandibular joint must be differentiated from other reasons why a patient is unable to open his mouth properly. It can be treated by various methods. It is the purpose of this paper to (a) Present various cases with different disorders that had lead to a restricted mouth opening and (b) Report upon the long-term post-operative results achieved by having applied various treatment options for true ankylosis of the temporomandibular joint (TMJ).

In 40 patients a true ankylosis was treated surgically by applying one of the two protocols: Either by interposing silastic sheetings or by implanting a TMJ prosthesis made of metal and consisting of 2 parts, a condylar head and a temporal fossa. Twenty patients could be followed up after 113 months on average - 13 patients of these have been treated by interposition of silastic and 7 have received endoprostheses. In 7 other patients, different reasons were found inhibiting freely opening the mouth. Congenital bony ankylosis of upper and lower alveolar processes, congenital or acquired bony fusion of the coronoid process with the zygomatic arch and/or temporal bone, acquired ankylosis between mandible and lateral pterygoid plate, ossifying myositis, or fibrosis of masticatory muscles following tumour irradiation. Not all of these could be operated upon and not all of these could be followed up. However, all patients operated upon followed a strict postoperative physiotherapeutic regimen.

Long-term follow-up maximum interincisal distances (MiDs) were callipered: 34mm (mean; min. 22, max. 52) following silastic sheeting; 18mm (mean; min. 10, max. 23) following endoprosthesis implantation. In the one of the two patients who could be followed up after ankylosis of the coronoid with the temporal bone, the MiD measured 49mm 1 year postoperatively. In that one of the two patients who could be operated because of a unilateral bony fusion between the mandible and the pterygoid plate, MiD was only 26mm 8 years postoperatively. And in the one of the two males who could be followed up 8 years after operation of myositis ossificans, MiD measured 50mm.

There are several possible reasons why a patient cannot open his mouth widely. Six of these have been touched upon, 4 of these have been operated upon. For true ankylosis silastic (sheeting or blocks) is felt to be the best material for interposition following osteotomy. Postoperative physiotherapy is a conditio sine qua non - it is the second most important part for every type of treatment for ankylosis.