Vertebral subluxation during three-column osteotomy in surgical correction of adult spine deformity: incidence, risk factors, and complications.

PURPOSE: To investigate incidence, risk factors, and complications of vertebral subluxation (VS) during three-column osteotomy in surgical correction of adult spine deformity.

METHODS: Adult spine deformity patients who underwent three-column osteotomies including VCR, PSO, and other modified types from March 2000 to December 2014 in our center were retrospectively reviewed. The following parameters were measured pre- and postoperatively: Cobb angle of main curve, global kyphosis, sagittal vertical axis, and kyphosis flexibility. Radiographic parameters between groups (VCR vs. PSO and subluxation vs. non-subluxation) were compared.

RESULTS: 171 ASD patients were recruited, 18 of which (10.5%) developed sagittal vertebral subluxation at the osteotomy site. 5 of 18 patients (27.8%) developed neurological complications after surgery. For these five patients, two patients got partial recovery, and three got complete recovery at 2-year follow-up. 116 patients underwent PSO, 12 of which (10.3%) developed sagittal vertebral subluxation. In 55 patients receiving VCR, 6 (10.9%) developed sagittal vertebral subluxation. No significant difference was noted between the two groups (P > 0.05). The mean age of VS group was larger than that of non-VS group (46.2 vs. 34.2, P < 0.05). VS group had less kyphosis flexibility (11 vs. 23%, P < 0.05). More patients in VS group had preoperative sagittal VS as compared to non-VS group (77.8 vs. 20.9%, P < 0.05). VS group had more neurological complications than non-VS group (25 vs. 5.4%, P < 0.05).

CONCLUSION: VS occurred in one-tenth of patients receiving three-column osteotomies, one-fourth of which would develop neurological deficits. Older age, rigid kyphosis, and the pre-existence of VS were risk factors for developing VS.