To report the clinical findings and results of the surgical treatment of the spinal pseudarthrosis in ankylosing spondylitis patients.

We reviewed 24 destructive vertebral lesions in 15 patient with ankylosing spondylitis who underwent pseudarthrosis repair and/or correction of kyphotic deformity. We assessed the clinical, laboratory, pathological and radiological findings. We performed anterior interbody fusion with or without Smith-Petersen osteotomy (SPO) at the level of pseudarthrosis. Pedicle subtraction osteotomy (PSO) was performed additively at lumbar spine in severe kyphotic patients. Clinical outcomes and complications were assessed.

Traumatic history and inflammatory reaction were not universal findings. Histopathological specimens showed fibrous degeneration with sclerotic bony spicules and mild chronic inflammation. We performed AIF with SPO in 12 kyphotic patient with additional PSO in 6 patients. Posterior interbody fusion was performed in non-kyphotic patients. Radiolographic results demonstrated solid union of pseudarthrosis at average 4.2 months after operation and sagittal imbalance was improved from 24 cm to 4.2 cm at follow up. The subjective satisfactions of the patients at the last follow up were excellent or good in all of the cases.

The principal etiology of pseudarthrosis in ankylosing spondylitis thought to be a mechanical weakness of unfused segment. Most of patients have had good clinical results by surgical stabilization of destructed anterior column with or without correction of deformity in combination with SPO and PSO.