Transarticular fusion for treatment of cystic lesion arising from an odontoid fracture

Odontoid fractures are the most common upper cervical spine fracture. There are two mechanisms in which odontoid fractures occur, most commonly hyperflexion of the neck resulting in displacement of the dens anteriorly and hyperextension resulting in posterior dens displacement. Type 2 fractures are the most common and are associated with significant non-union rates after treatment. One possible consequence of an odontoid fracture is a synovial cyst, resulting in spinal cord compression, presenting as myelopathy or radiculopathy. Synovial cysts as a result of spinal fracture, usually of the facet joint, are most common in the lumbar region, followed by the thoracic and then cervical region; cervical cysts are rare. Fracture and subsequent cyst formation is thought to be related to hyper-motion or trauma of the spine. This is reinforced by the appearance of spinal synovial cysts most commonly at the level of L4/5; this being the region with the biggest weight-bearing function. The most common site of cervical cyst formation is at the level of C7/T1; this is a transitional joint subjected to unique stress and mechanical forces not present at higher levels. Treatment of a cervical synovial cyst at the level of the odontoid is challenging with little information available in the literature. The majority of cases appear to implement posterior surgical resection of the cyst, with fusion of adjacent cervical vertebrae to stabilise the fracture, resulting in restricted range of movement.

We describe a case concerning a 39-year-old female who presented with uncertain cause of odontoid fracture, resulting in a cystic lesion compressing the upper cervical spinal cord.

Minimal invasive surgery of C1/C2 transarticular fusion was successfully performed resulting in significant improvement of neurological symptoms in this patient. At 1-year follow-up, the cyst had resolved without surgical removal and this was confirmed by radiological measures.