Traumatic ankylosis of the right temporomandibular joint: demonstration by 3D spiral CT

Clinical History

The patient presented with symptoms of right temporomandibular joint pain and restriction of movement. The patient was evaluated with sagittal CT scans with closed and open month and 3D spiral CT.

Imaging Findings

The patient presented with problems of chin motion during speaking and eating. There was also pain during movement of the temporomandibular joint. She had been involved in a traffic accident approximately 14 months previously and sustained damage to the right side of her face. Since than, her complaints had gradually increased. On physical examination, there was a slight facial asymmetry and restriction in the opening of the mouth.

CT examination was performed. Firstly, sagittal CT sections were taken with open and closed mouth. There was marked irregularity on the cortical surface of the mandible condyle and fossa temporomandibularis. The joint space was narrow and, on the sections taken with open mouth, no movement was detected on the right side when compared with the left side (Fig. 1). Secondly, axial spiral CT sections were taken with 3mm slice thickness. 3D spiral CT sections were formed from these thin sections with 30° rotation to the vertical plane and 10° rotation to the transverse plane. On these sections, it was clearly seen that the right temporomandibular joint showed bony ankylosis. There was complete loss of joint space when compared with the left side (Fig. 2).

Discussion

Temporomandibular joint (TMJ) ankylosis is a disabling condition of mastication. Hypomobility affects the surrounding structures as well as the TMJ. As early as 1938 Kazanjian classified TMJ ankylosis into two types: intra-articular and extra-articular ankylosis (1). The present classification includes bony, fibrous, fibro-osseous, complete and incomplete ankylosis (1).

The causes of TMJ ankylosis are trauma and local systemic infection. Trauma, which is the most important aetiological factor in causing TMJ, often results in haematoma, which eventually organises and ossifies. In some cases, excessive bone formation causes bony thickening in front of the tragus. The thickness of the bony block varies with the severity of the injury. Infection in this area is caused by otitis media, mastoiditis or haematogeneous infections. Other aetiological factors are rheumatoid arthritis, Paget's disease, ankylosing spondylitis, pseudohypoparatroidism, psoriasis and burns.

Intrinsic opening shows the severity of the ankylosis. Sagittal plane CT sections with open and closed mouth are crucial in the detection of joint movement and visualisation of articular surfaces. A 3D spiral CT section, obtained through thin axial CT sections, provides better anatomical information and contributes to the diagnosis.

Roentgenographic examination has long been a useful diagnostic tool for TMJ disease. The methods include TMJ tomography and panoromic radiography. 3D CT is one of the presurgical roentgenographic diagnostic tools and is reconstructed from two-dimensional CT scan images.

Differential Diagnosis List

Final Diagnosis

Bony ankylosis of the right temporomandibular joint

URL:	https://www.eurorad.org/case/1645
DOI:	10.1594/EURORAD/CASE.1645
ISSN:	1563-4086