Chance Fracture Pattern Presenting in Proximal Junctional Failure.

INTRODUCTION

We present a case series of proximal junctional failure due to a Chance-type fracture.

METHODS

This is a retrospective review of patients who developed proximal junctional kyphosis because of Chance-type proximal junctional failure after spinal fusion for adult spinal deformity.

RESULTS

Fifteen patients were identified (4M:11F). The average age was 61.4 years (range, 39 to 77). The mean time to fracture identification was 25.4 days (range, 3 to 65). The average number of levels instrumented was 6.7 (range, 2 to 17). No patients had antecedent trauma before fracture onset. In 67% of cases with a lumbar upper instrumented vertebra (UIV), there was overcorrection of lumbar lordosis (LL) and/or lower LL. The five cases with a lower thoracic UIV had undergone notable correction of preoperative thoracolumbar junction kyphosis. 14 of 15 patients were treated with extension of fusion. Pedicle screws at the fracture level were salvaged by changing to an anatomic trajectory.

CONCLUSION

Continued pain at 6 to 12 weeks with radiographs showing an increased proximal junctional angle and cephalocaudal pedicle widening at the UIV should raise suspicion for this unique fracture pattern. A CT scan is recommended. Low bone density, LL and/or lower LL overcorrection, and selection of lower thoracic UIV in the setting of notable thoracolumbar junction correction may contribute to fracture risk.