A 58-year-old man with long-standing rheumatoid arthritis presents with C1–C2 instability (atlantoaxial subluxation) confirmed on MRI showing >3.5 mm anterior atlanto-dens interval and spinal cord compression. He has neck pain with myelopathic signs. The definitive surgical treatment is:

• A Soft cervical collar and physiotherapy
• B Halo vest immobilisation for 12 weeks
• C Posterior C1–C2 fusion (atlantoaxial arthrodesis) ✓
• D Anterior odontoid screw fixation

Explanation

Rheumatoid atlantoaxial subluxation with myelopathy and >3.5 mm atlanto-dens interval (or >5 mm posterior atlanto-dens interval indicating cervicomedullary compression) requires surgical stabilization. Posterior C1–C2 fusion (atlantoaxial arthrodesis) using techniques such as Harms technique (polyaxial screws C1 lateral mass + C2 pedicle screws with rod) is the gold standard; it directly addresses the instability and protects the cord. Halo vest is a temporizing measure, not definitive. Odontoid screw fixation is for acute type II odontoid fractures, not rheumatoid erosive disease. Conservative measures are inadequate once myelopathy is present.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.