Mandibular condylar fractures and acute atlanto-axial subluxation. Part 1 - A new clinical and nosographic evidence.

AIM: The aim of this study was to analyze the acute repercussions of condylar mandibular fractures on occipital-atlanto-axial joint.

METHODS: Twenty-five non-consecutive cases (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 considered. 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 cases of fractures of the mandibular condyle an acute alteration of the junctional atlanto-axial structures was present. In case of unilateral solitary condylar fractures the authors have observed an atlas rotation, homolateral to the side of the condylar fracture, independent from the level of the fracture (intra- or extracapsular). The rotation seems to be proportional to the entity of the condylar fragments dislocation on the horizontal plane and it causes a modification of the articular relations between atlas and axis (atlanto-axial subluxation) and between the atlas and the occipital bone. The authors have observed a constant derangement of the cranio-axial joint on the three planes of the space. In particular, on the vertical plane the CT reconstructions show on the right and left side a different height between the atlanto-axial articular spaces. The largest one is homolateral to the side of the condylar fracture. In case of unilateral condylar fractures associated with other mandibular fracture (homolateral or not) the authors have observed the same alterations of the occipital-atlo-epistropheal joint, but while on the horizontal plane the rotation of the atlas is always homolateral to the condylar fracture, on the vertical plane the largest atlanto-axial articular space is homolateral to the mandibular fracture with more dislocation of the fragments of fracture (usually the associated not homolateral mandibular fracture). In case of bilateral condylar fractures the authors have observed no alteration of the cranio-cervical joint. In the non-equivalent fractures, they have observed the atlas rotation on the horizontal plane and the junctional derangement on the vertical plane, homolateral to the condylar fracture with greatest dislocation. In the control group the loss of the physiological cervical lordosis has been observed. Alterations on the horizontal and vertical planes, as the rotation of the atlas, atlanto-axial subluxation or the joint derangement, instead, has never revealed.

CONCLUSIONS: The authors state that these results represent a new nosographic entity associated with the condylar mandibular fractures with important clinical, insurance and legal repercussions.