CC
A 62-year-old male presents to your office with a complaint of a limited mouth opening for the past several years.
Mandibular hypomobility can be caused by disorders that are intra- or extraarticular (pseudoankylosis). Intraarticular disorders are further classified based on the type of tissue involved (fibrous, bone, or mixed). There is no gender predilection in temporomandibular joint (TMJ) ankylosis. There is, however, a bimodal age distribution. Whereas growing patients most often develop ankylosis because of an exaggerated healing response to trauma, older adults typically develop ankylosis after longstanding degenerative joint pathologies or iatrogenic procedures.
HPI
The patient was involved in a motor vehicle crash a couple of years ago during which he suffered multiple facial fractures. He underwent open reduction and internal fixation of his panfacial fractures, including his parasymphysis. He also had bilateral condylar fractures that were treated with closed reduction. Shortly after surgery, he was never able to regain his premorbid mouth opening. He reports his range of motion (ROM) continued to slowly decrease over the next couple of years until he was no longer able to open his mouth. His limited ROM has led to difficulties eating, speaking, and maintaining oral hygiene. In growing patients, ankylosis can also lead to facial asymmetry because the normal mandibular growth is perturbed.
The development of ankylosis can often be insidious with slow but progressive and relentless limitations in ROM.
PMHX/PDHX/medications/allergies/SH/FH
The patient has well-controlled hypertension but otherwise has a noncontributory medical history.
In the setting of trauma, patients may often be very young and without any underlying comorbidities.
Patients with degenerative joint diseases and systemic arthritides may often develop ankylosis because of their disease progression or iatrogenic surgical insults. They can present with associated myofascial pain disorders, as well as signs and symptoms in other joints affected by their disease process. Infection is also a very common etiological factor in the development of ankylosis, and any septic joint arthritis would need to be treated aggressively to reduce the incidence of this complication.
Examination
The patient appears well and is in no apparent distress.
He is orthognathic in appearance and has balanced facial proportions. There is no pain to palpation of his joints or his masticatory muscles. Palpation of the joints does not reveal any underlying masses. There is a severe limitation in his ROM with a maximal incisal opening of 4 mm and a hard-end feel. The neurosensory examination results are normal.
The intraoral examination is quite limited because of the severely restricted mouth opening. There are signs of poor oral hygiene, including caries, retained roots, and plaque and calculus build-up.
Imaging
The panoramic radiograph is an invaluable screening tool, particularly in patients with TMJ dysfunction. It is quick and inexpensive and provides a gross overview of the joint anatomy. Large sclerotic lesions, advanced degenerative changes, and ankylotic bone masses can all be readily seen on a panoramic radiograph. Existing hardware and malunions of facial bones can also corroborate a history of trauma.
For a more thorough appreciation of the bony architectural changes, a medical-grade computed tomography (CT) scan with 1-mm thickness of slices is the study of choice. Contrast is not necessary if a neoplastic or infectious process has been ruled out. Although magnetic resonance imaging may be useful in diagnosing a fibrous ankylosis, it provides no additional information in bony ankylosis.
In our patient, the panoramic radiograph reveals significant pathology in both joints, which we can presume to be the result of bony ankylosis from bilateral condylar head fractures ( Fig. 71.1 ).
The CT images reveal the true extent of the joint destruction. There is an absent joint space with fusion of the mandibular condyle to the glenoid fossa. The medial extent of bone can represent an old malunion of a condylar head fracture or heterotopic bone ( Fig. 71.2 ).
Given the increased risk of injuring vital structures when operating in an area of aberrant anatomy, a CT angiogram was also ordered to evaluate the relationship of the ankylotic bone masses with surrounding vascular structures. This knowledge can be invaluable when planning surgery ( Fig. 71.3 ).
Labs
The patient underwent routine preoperative laboratory work, including a complete blood count and a basic metabolic panel. Additional laboratory work and investigations are dictated by underlying comorbidities and often at the discretion of the preoperative clinic after a full history and physical examination.
In the event of a systemic arthritis, a referral to a rheumatologist would be prudent for a thorough evaluation at time of consultation.
Assessment
The patient was diagnosed with a complete bony ankylosis of his bilateral TMJs.
In fibrous ankylosis, the joint space is occupied by a dense fibrous scar that ultimately replaces the articular disk. Bony ankylosis develops from longstanding fibrous ankylosis and is more destructive. The most common cause is trauma. It is theorized that an intraarticular hematoma, along with scarring and excessive bone formation, leads to progressively limited mandibular ROM. This manifest itself as an initial loss of translation, then eventual rotation, and finally a severe restriction in opening after the condyle fuses to the glenoid fossa. Other causes of ankylosis include infectious arthritis, systemic autoimmune arthritides, and iatrogenic surgical procedures.
Treatment
The treatment objectives in the patients with ankylosis are to restore mouth opening and to prevent or reduce the risk of reankylosis. In growing patients, one faces the additional challenge of attempting to restoring symmetric mandibular growth.
Treatment is begun by performing a gap arthroplasty, which includes resection of the ankylotic bone and creation of a critical sized defect of 2 cm to reduce the risk of reankylosis. An ipsilateral coronoidectomy is always performed, and a contralateral one should be considered if the ROM remains restricted after the gap arthroplasty and ankylosis release.
Reconstruction of the TMJ differs in a growing patient versus an adult. In a growing patient, distraction osteogenesis or costochondral grafts (CCGs) are the currently acceptable treatment options. The CCG is the autogenous graft of choice for reconstruction of the condyle because of its similarity in shape and potential for continual growth. Alloplastic joint reconstruction is a matter of controversy because of lack of growth. As a result, one would have to consider either replacement of the joint or orthognathic surgery as the patient continues to grow.
In adults, custom-made alloplastic joints are the gold standard. Historically, these were done in two stages. Gap arthroplasty, postoperative CT scanning, and creation of a stereolithic model for joint fabrication used to be the workflow. Now with improvements in virtual planning and the accuracy of surgical templates and guides, treatment can almost always be performed in one stage. During single-stage surgery, you need to prepare the glenoid fossa and ramus of the mandible to receive the custom components. This is performed using cutting guides and templates ( Fig. 71.4 ).
