Radiographical and Clinical Outcomes of Posterior Column Osteotomies in Spinal Deformity Correction.

STUDY
DESIGN: Prospectively enrolled, retrospectively analyzed case series.
OBJECTIVE: To evaluate a large series of pediatric patients/patients with adult spinal deformity undergoing surgery with posterior column osteotomies (PCOs). SUMMARY OF BACKGROUND DATA: Osteotomies of the posterior column (Smith-Petersen or Ponté) are used to reduce kyphosis, increase lordosis, or increase spinal flexibility. However, little focused evidence exists regarding the efficacy and safety of this technique.
METHODS: A total of 128 consecutive patients underwent posterior spinal fusion with PCOs with minimum 2-year follow-up. Seventy-five were primary surgical procedures; 53 were revisions. Data were collected from hospital charts, clinic notes, radiographs, and standardized questionnaires (Scoliosis Research Society-30 and Oswestry Disability Index).
RESULTS: A total of 128 patients aged 37.6 ± 21 years underwent 518 PCOs (mean, 4.0 ± 2.2 yr) with 14.4 ± 3 mean instrumentation levels, with 3-year (range, 2-6.8 yr) average follow-up. PCOs were used for kyphosis correction in 49%, scoliosis correction at the apex of a curve in 13%, and both in 38%. One hundred six patients had complete radiographical data available for evaluation. Mean kyphosis correction per PCO was 8.8° ± 7.2°, varying with patient age (10.2° for those younger than 21 yr vs. 7.7° for those 21 yr or older, P < 0.0001) and region of the spine: thoracolumbar (T10-L2) 11.6°, lumbar (L2-S1) 9.4°, midthoracic (T6-T10) 7.2° and proximal thoracic (T1-T6) 3.6°. With PCOs at the apex of a curve, the maximum coronal Cobb decreased from 66° ± 21° to 31° ± 14° (P < 0.0001). Average estimated blood loss was 1419 ± 887 mL, correlating with greater age (P < 0.0001) and more instrumented levels (P < 0.0001), but not with the number of PCOs (P = 0.32). Complications occurred in 31 (24.2%) patients, including 4 radiculopathies (none attributable to PCOs). Complications did not correlate with the number of PCOs (P = 0.5). Six (4.7%) patients had loss of spinal cord monitoring or a failed wake-up test that could be attributed to overcorrection with PCOs, but none had postoperative deficits. Oswestry Disability Index scores improved (34.4 ± 17 to 23.6 ± 18, P < 0.0001), as did normalized Scoliosis Research Society-30 scores (63.7 ± 13 to 76.4 ± 15, P < 0.0001).
CONCLUSION: Patients in this series undergoing posterior spinal fusion with PCOs achieved overall favorable outcomes for spinal deformity correction. The number of PCOs did not correlate with increased estimated blood loss or complications. The main technical concern was overcorrection, but neurological consequences associated with overcorrection were identified by intraoperative spinal cord monitoring and wake-up tests, and no patients experienced permanent neurological deficits related to PCOs. LEVEL OF EVIDENCE: 4.