Study design: Closing-opening wedge osteotomy (COWO) had been performed by the senior author (K.C.) since 1998. A study had been conducted to evaluate the efficacy of COWO since 2000.
Objective: Assess COWO for sagittal imbalance requiring more than 35 degrees lordotic correction at the level of osteotomy.
Summary of background data: Correction of sagittal imbalance commonly uses pedicle subtraction osteotomy or closing wedge osteotomy (CWO). Anatomic limitation of 1 vertebral body restricts CWO to approximately 35 degrees of lordosis at the osteotomized vertebra. Further movement often requires over 1 CWO to obtain adequate correction, but can also be achieved using COWO at a single level by fracturing the anterior vertebral cortex. The efficacy of COWO for the treatment of sagittal imbalance is unclear.
Methods: Eighty-three consecutive patients treated for sagittal imbalance with lumbar COWO with a minimum follow-up of 2 years were analyzed. Radiographic analysis included assessment of thoracic kyphosis, lumbar lordosis, lordosis through COWO site, sagittal translation at the site of osteotomy, and sagittal balance. Outcomes analysis used the Scoliosis Research Society questionnaire. Complications and radiographic findings were analyzed.
Results: The average increase in lordosis and improved sagittal balance were 81.9 degrees and 17.1 cm. Mean correction through the osteotomy site was 42.2 degrees (range, 31-55 degrees). Sagittal translation occurred in 40% of these patients. No vascular injury occurred. Although 3 patients developed lumbosacral pseudarthrosis, the COWO area was unaffected in all patients. Nine patients developed cephalad junctional kyphosis and 2 patients developed caudad junctional kyphosis. Most patients reported improvement in terms of pain, self-image, and function as well as overall satisfaction with the procedure.
Conclusion: COWO is a useful procedure for patients with sagittal imbalance requiring more than 35 degrees lordotic correction through the osteotomy site. A worse clinical result is associated with increasing patient comorbidities, pseudarthrosis in lumbosacral fusion, and junctional kyphosis.