Unilateral spacer distraction of the subaxial cervical facet joint for the treatment of fixed coronal malalignment of the craniovertebral junction

INTRODUCTION: The standard treatment for a fixed coronal malalignment of the craniovertebral junction is an anterior and/or posterior column osteotomy (PCO) plus instrumentation. However, the procedure is very challenging, carrying an inherently high risk of complications even in experienced hands. This case series demonstrates the usefulness of an alternative treatment that adds a unilateral spacer distraction (USD) to the subaxial cervical facet joint to promote coronal realignment and fusion. MATERIALS AND METHODS: A single-center retrospective study of the patients with fixed coronal malalignment of the craniovertebral junction caused by different etiologies treated with USD in the concavity side with PCO in the convexity side of the subaxial cervical spine. Demographic characteristics and radiological parameters were collected with special emphasis on clinical and radiological measurements of coronal alignment of the cervical spine. RESULTS: From 2012 to 2019, four patients were treated with USD of the subaxial cervical spine complementing an asymmetrical PCO at the same level. The causes of coronal imbalance were congenital, tuberculosis, posttraumatic, and ankylosing spondylitis. The level of USD was C2–C3 in three patients and C3–C4 in one patient. A substantial coronal realignment was achieved in all four. One patient had an iatrogenic vertebral artery injury during the dissection and facet distraction and developed Wallenberg's syndrome with partial recovery. CONCLUSIONS: USD of the concave side with unilateral PCO of the convexity side in the subaxial cervical spine is a promising alternative treatment for fixed coronal malalignment of the craniovertebral junction from different causes.