Unilateral lateral mass-facet fractures with rotational instability: new classification and a review of 39 cases treated conservatively and with single segment anterior fusion.

OBJECTIVE

This study examined the clinical and radiologic results of cervical spine injuries associated with a unilateral lateral mass-facet fracture (ULMFF) in an attempt to clarify the fracture pattern and treatment strategies using single-level anterior fusion.

METHODS

From July 2003 to June 2006, adult patients, who had sustained ULMFFs of the middle cervical spine, were reviewed retrospectively. The fractures were classified into six subtypes using roentgenogram and computed tomography imaging with three-dimensional analysis. Initially, 15 patients without severe translation and kyphosis were treated with external immobilization and 24 patients were treated surgically with anterior fusion. The fusion state and spinal alignment were evaluated at the follow-up visits.

RESULTS

Thirty-nine patients had 27 lateral mass fractures and 14 facet joint fractures. The lateral mass fractures were divided into the following four subtypes: unilateral spondylolithesis in 16, separation fracture in 5, comminution type in 4, and split type in 2. Facet fractures with/without facet dislocation were observed in seven patients. Twelve patients who received conservative management required delayed fusion due to persistent pain and late instability. Overall, 36 patients, with the exception of three cases with a successful result by external immobilization, underwent surgery using single-level anterior fixation with anterior plating. A poor radiologic outcome was observed in eight patients after the procedure. Five cases showed incomplete reduction or a failure of the reduction. Three cases had adjacent instability and malalignment despite the early fusion observed due to short-segment fusion in the separation type.

CONCLUSION

This retrospective review of ULMFF showed that nonsurgical treatment is usually unsuccessful, and early single-level anterior arthrodesis has a favorable outcome. However, exclusive two-level stabilization or pedicle screw fixation needs to be considered in the separation type.