Analysis of temporomandibular joint ankylosis caused by condylar fracture in adults.
OBJECTIVE
To analyze the main causes of temporomandibular joint (TMJ) ankylosis from condylar fracture in adults through a retrospective study.


METHODS
The history and computed tomographic (CT) scans of patients diagnosed with ankylosis caused by mandibular condyle fracture treated in a closed fashion from 2010 to 2012 were reviewed in the department of oral surgery. According to the relation between the stump of the ramus and the TMJ fossa, condylar fractures were divided into 3 grades: grade 0, in which the ramus stump is in the fossa but without contact to it; grade 1, in which the stump of the ramus is in the fossa and attached to it; and grade 2, in which the stump of the ramus is laterally displaced out of the fossa. Other factors, such as type of condylar fracture, displacement of the fractured fragment, position of the disc, and the presence of concomitant mandibular fractures, also were analyzed for ankylosis development.


RESULTS
Of the 51 patients diagnosed with TMJ ankylosis, 13 patients (24 ankylosed joints) had full CT scans from injury to ankylosis, which showed that all condylar fractures were intracapsular fractures (ICFs), with sagittal fractures comprising 70%. Regarding the relation between the stump of the ramus and the TMJ fossa, no joints were classified as grade 0 (0%), 10 joints were classified as grade 1 (41.7%), and 14 joints were classified as grade 2 (58.3%). All discs were displaced with the fracture fragment, and the posterolateral retrodiscal tissue was torn. Among the condyle fractures leading to ankylosis, 77% featured symphysis fractures with widening of the mandibular arch.


CONCLUSIONS
The relation between the ramus stump and the TMJ fossa plays an important role in the prognosis of condylar fracture. Grade 0 is less likely to cause ankylosis; grade 1 is more likely to cause ankylosis and is the relative indication for surgery; and grade 2 is the strongest predictor of ankylosis and is the absolute indication for surgery. Other risk factors are sagittal ICFs and combined mandibular fractures with widening of the mandibular arch.
Associate Professor, Department of Oral Surgery, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Key Laboratory of Stomatology, Shanghai, China.
Dongmei
D
He
Resident, Department of Oral Surgery, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Key Laboratory of Stomatology, Shanghai, China.
Yihua
Y
Cai
Professor, Department of Oral Surgery, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Key Laboratory of Stomatology, Shanghai, China. Electronic address: dongmeihe119@yahoo.com.
Chi
C
Yang
D000293:Adolescent; D000328:Adult; D000844:Ankylosis / Q000209:etiology*; D003724:Dental Arch / Q000293:injuries; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D004204:Joint Dislocations / Q000145:classification / Q000150:complications; D008297:Male; D008335:Mandibular Condyle / Q000293:injuries* / Q000473:pathology; D008337:Mandibular Fractures / Q000145:classification / Q000150:complications*; D008875:Middle Aged; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors; D013701:Temporal Bone / Q000473:pathology; D019224:Temporomandibular Joint Disc / Q000293:injuries; D013705:Temporomandibular Joint Disorders / Q000209:etiology*; D014057:Tomography, X-Ray Computed / Q000379:methods; D055815:Young Adult