Surgical management of remote, isolated type II odontoid fractures with atlantoaxial dislocation causing cervical compressive myelopathy.

Objective: The remote (more than 6 mo after injury) and isolated (not associated with any other cervical spinal fractures) Type II fractures of the odontoid (RI IIO) are unique in being inherently unstable and prone to malunion or nonunion, leading to cervical compressive myelopathy. The present study discusses their surgical management.

Methods: Nineteen patients with RI IIO with atlantoaxial dislocation (AAD) causing compressive myelopathy were treated. Their preoperative disability was graded as Grade I: neurologically intact (presented with hyperreflexia and mild spasticity; n = 3); Grade II: independent with minor disability (n = 7); Grade III: partially dependent for daily needs (n = 6); and Grade IV: totally dependent (n = 3). They were classified as irreducible AAD caused by 1) malunited fracture of the odontoid (n = 2), 2) fixed anterolisthesis of the anterior arch of a C1-fractured odontoid complex (n = 3), and 3) fixed retrolisthesis of the anterior arch of a C1-fractured odontoid complex (n = 1); and reducible AAD caused by 1) mobile AAD (n = 11) and 2) hypermobile AAD (n = 2). The patients with irreducible AAD underwent a transoral decompression and posterior fusion; those with a malunited fracture underwent surgery immediately, whereas those with fixed anterolisthesis or retrolisthesis were initially placed in cervical traction. The patients with reducible AAD underwent a direct posterior fusion. In the patient with "hypermobile" AAD, a proper alignment of the fractured segment of the odontoid relative to the body of the axis in a neutral position of the neck was ensured before the posterior fusion was performed.

Results: At follow-up (mean, 15.37 +/- 9.67 mo), three patients in Grade I maintained their neurological status. Of the seven patients in Grade II and six in Grade III, five had improved to Grade I, and eight were in Grade II. The three patients in Grade IV improved to Grade I, II, and III, respectively.

Conclusion: The patients with RI IIO may be divided into five groups on the basis of their differing management protocols. There is a considerable risk of delayed myelopathy unless surgical reduction and stabilization are performed. Posterior stabilization is the preferred option in dealing with these fractures. Despite the presence of severe neurological deficits and the prolonged duration of symptoms, a significant neurological improvement usually occurs after surgery.