Septic Arthritis of an Atlantoaxial Facet Joint with Normal Inflammatory Markers: Case Report and Literature Review

Septic arthritis of the atlantoaxial facet joint is extremely rare. Contiguous spread to the median atlantoaxial joints with subsequent dens erosion can lead to atlantoaxial instability. Misleading normal inflammatory markers can result in delayed diagnosis and catastrophic consequences.

A 56-year-old man presented with right-sided neck pain that had lasted for 2 days. He did not have fever or chills, and his serum C-reactive protein and erythrocyte sedimentation rate were normal. The patient was diagnosed with acute neck strain and treated conservatively. The pain continued for the next 3 weeks; cervical spine radiographs demonstrated normal findings with the exception of degenerative changes. The patient was treated with physical rehabilitation for the presumed neck strain and degenerative changes of the cervical vertebrae. Worsening neck pain and stiffness prompted a magnetic resonance imaging study obtained 5 weeks after the initial presentation, which showed an epidural collection with septic arthritis of the right facet and median atlantoaxial joints. Computed tomography demonstrated severe dens erosion. Surgical evacuation of the abscess and occipitocervical fusion were performed. Pathologic evaluation of tissue obtained during surgery demonstrated the presence of an infection, and Streptococcus anginosus grew from cultures.

Infection must be considered in the differential diagnosis for neck pain when imaging findings are suggestive of an infectious process, even in an afebrile patient with normal C-reactive protein and erythrocyte sedimentation rate levels. Magnetic resonance imaging and computed tomography can play a critical role in such cases, potentially leading to a more timely diagnosis.