Mandibular condylar fractures and acute atlanto-axial subluxation Part 2 A physiopathological factor for the cervical spine sprain.

AIM: The aim of this study was to analyze the physiopathology of the acute cervical injure in the event of mandibular condylar fractures. METHODS: As in the Part 1, 25 non-consecutive cases of condylar mandibular fractures (16 males and 9 females, mean age: 22.96/range 14-36 years) observed and treated in the Maxillofacial Surgery Department of the University of L'Aquila, have been studied. Types of fractures examined included: unilateral: 19 cases (solitary: 12; associated with other mandibular fractures: 7, homolateral: 2); bilateral: 6 cases (equivalent: 2, not equivalent: 4). A control group was constituted of 10 patients, 5 males and 5 females, aged from 19 to 24 years (mean range: 21.6) suffering from acute isolated cervical distorsion (whiplash). The study has been performed by means of the analysis of X-ray and computed tomography (CT)-CT/3D of the mandibular condylar regions, the occipital-atlanto-axial structures and the cervical region. RESULTS: In all the patients the following constant alterations that link up with these fractures have been observed: the rotation of atlas, the atlanto-axial subluxation and the derangement of the occipital-atlanto-epistropheal joint, homolateral to the side of the mandibular condylar fracture. The cervical spine shows the constant loss of physiological lordosis with hinge between C3 and C4. In the whiplash, as the authors have been able to assess in the control group, there are no alterations of occipital-atlanto-axial joint and the kinetic vector is placed on the longitudinal plane. In the mandibular condylar fractures the kinetic mechanism is completely different regarding the whiplash. The point of entry is the chin and the kinetic vector is oriented down-up, sometimes oblique in the opposite side. Subsequently the kinetic force is transmitted throughout the mandibular structure and causes the condylar or bicondylar fracture. The kinetic vector is placed before on the vertical plane, then on the horizontal plane and later on the vertical plane. Therefore the dynamics of the crash cannot cause the swaying of the head as in the whiplash. Indeed in the mandibular condylar fractures the authors have observed the cervical distortion with the loss of lordosis on the sagittal plane without whiplash and also a constant derangement of the cranio-cervical joint and the atlanto-axial subluxation. CONCLUSIONS: These results allow to delineate a different physiopathological mechanism: in the event of mandibular condylar fractures, the sprain of the cervical spine seems to be caused by the acute atlanto-axial subluxation.