Fracture of the articular eminence Report of a case
Olga Keith, Geoffrey M. Jones, J o n a t h a n P. S h e p h e r d University Department of Oral Medicine, Surgery and Pathology, Bristol Dental Hospital and School, England
O. Keith, G. M. Jones, J. P. Shepherd. Fracture o f the articular eminence. Report o f a case. Int. J. Oral MaxiIlofac. Surg. 1990; 19: 79-80. Abstract. A case o f c o m p o u n d fracture of the articular eminence is presented. T h e injury was sustained as a result o f direct t r a u m a w h i c h also caused a m a n d i b u l a r symphyseal fracture. M a n a g e m e n t comprised repositioning a n d supp o r t of the fractured f r a g m e n t by m e a n s o f sutures a n d the application o f intermaxillary fixation. T h e r e was no l o n g - t e r m limitation o f m a n d i b u l a r m o v e m e n t n o r was there neurological or hearing deficit as a result o f either injury or treatment.
Fractures involving the t e m p o r o m a n d i b u l a r j o i n t ( T M J ) are well d o c u m e n t e d a n d those affecting the condyle m a y be i n t r a - c a p s u l a r (condylar head) o r extra-
capsular (condylar neck a n d subcondylar) 5. F r a c t u r e s a f f e c t i n g the glenoid fossa m a y also occur 2'll, giving rise to bleeding f r o m the external a u d i t o r y me-
Key words: articular eminence; trauma; TMJ. Accepted for publication 26 October 1989
atus. Occasionally the condyle is displaced into the meatus, or even into the middle cranial fossa 6,8. The p u r p o s e o f this p a p e r is to r e p o r t an i n t r a - c a p s u l a r fracture involving only the articular eminence, such a case has n o t been rep o r t e d previously.
Fig. 1. Photograph showing pre-auricular laceration and fractured articular eminence (AE). PD = parotid duct; FN = facial nerve; FL = fracture line.
A 19-year-old male was admitted to hospital following a road traffic accident in which he was a rear-seat passenger. He had sustained a severe head injury, a fracture of the right parasymphyseal region of the mandible and a deep vertical laceration affecting the left pre-auricular area. Radiographs also showed an undisplaced spiral fracture of the left ramus. A C T scan revealed that small haemorrhages had occurred around the midbrain; but no abnormality of the skull base was reported. It was suspected that the laceration had severed the left parotid duct and branches of the facial nerve. The head injury was such that it was impossible to investigate either cranial nerve function or the integrity of the parotid duct. The left pre-auricular laceration was approximately 7 cm in length and extended inferiorly and anteriorly from the hairline through the masseter muscle and the anterior part of the superficial part of the parotid gland (Fig. 1). At operation an intact branch of the facial nerve was observed, passing across the upper aspect of the wound. The parotid duct was also seen to be largely intact in the lower part of the wound, although a minute perforation was detected. In the deepest part of the laceration a mobile fragment of bone was identified, approximately 0.5 cm × 0.5 cm in size, corresponding to the inferior aspect of the zygomatic process, and attached to the skull base by perios-
Keith et al.
teum. The head of the condyle was identified posteriorly, and the fragment was confirmed to be the articular eminence of the temporal bone. The articular tubercle was stabilised with chromic catgut sutures and the symphyseal fracture was immobilised by the application of intermaxillary fixation. This also resulted in positioning the condyles in the glenoid fossae, thus preventing further trauma to the healing eminence. The wound was closed in layers. The intermaxillary fixation was removed at 5 weeks and the mandibular fracture was found to be stable and the occlusion satisfactory. As the patient's neurological state improved, it became apparent that there was weakness of the facial nerve possibly due to transection of the nerves within the original wound.Concentric needle electrode sampling of the left orbieularis oculi and orbieularis otis muscles revealed no evidence of fibrillation potentials at rest. It was also possible to evoke clear motor responses when stimulating the facial nerve. The conclusion from these investigations was that there was no gross lower motor neurone abnormality and that the weakness was probably of upper motor neurone origin. There was no evidence of restricted mandibular movement, taste disturbance or hearing deficit on discharge or at 3 and 6 months...
Discussion The anatomy of the T M J dictates that a fracture of the articular eminence may be accompanied by damage either to chorda tympani, or to the anterior malleolar ligament. The T M J capsule, whose attachments extend over the eminence will be damaged in all cases. The chorda tympani passes medial to the superior joint space after its exit from the skull via the petrotympanic fissure, relaying taste sensation from the anterior two thirds of the tongue 6. Stretching o f the anterior malleolar ligament, at the point where it merges with the capsule and spheno-mandibular ligament inferiorly, may result in tearing of the postero-superior quadrant of the tympanic m e m b r a n e and an 80% reduction in hearing s . Any capsular damage may lead to scarring and subsequent limitation of movement. In the case presented here, radiological investigation o f the area including plain, tomographic and computerised tomographic views gave little useful in-
formation. N o attempt was m a d e to rigidly immobilise the fractured eminence, and this was followed by excellent healing. Interestingly, neither eminectomy 1°,1z,13, nor eminence augmentation 2,15, have been reported to be followed by particular complications, except for occasional facial nerve damage and intra-cranial perforation, and it is therefore not surprising that healing was uneventful. It seems likely, however, that early mobilisation might prevent long-term restriction of mandibular movements even in the presence o f constant trauma from the condyle during normal mandibular movements. For this reason it may have been more appropriate in this case to treat the mandibular fracture by small plate osteosynthesis so avoiding the use of intermaxillary fixation. CAWOOD1 in 1985 compared 50 successive cases o f mandibular fracture treated by small plate osteosynthesis with 50 successive cases treated by intermaxillary fixation. The test group recovered normal m o u t h opening within 4 weeks, whereas recovery of m o u t h opening in the control group was much slower a n d still incom~ plete after 15 weeks. With regard to the facial nerve involvement, nerve conduction studies showed that the weakness was probably due to an upper m o t o r neurone abnormality. I f the nerve had been found to be damaged at operation, then nerve exploration would have been indicated. T h o u g h there is controversy about the correct timing of the surgical repair of peripheral nerves 3'9, primary repair must be carried out within 7 days and ideally within 24 h of trauma. In this case, the eminence articularis fracture was c o m p o u n d through the pre-auricular skin, and easily detected. Whilst this fracture does not appear to have been reported previously, it may be that many such injuries remain undetected due to difficulties with radiography and the presence of more major injuries which tend to 'mask' this fracture.
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