Lumbosacral osteotomy to correct PI-LL mismatch in the presence of abnormally high pelvic incidence

Study design A case report. Summary of background data It is important to achieve optimal sagittal balance in spinal deformity surgery by matching LL to PI. A Lumbar osteotomy to increase lordosis is often the method used to achieve this in adult patients. However, in patients with high PI with compensatory lumbar hyperlordosis, providing further lordosis does not address the root cause. The paper will describe a technique of lumbosacral osteotomy to address sagittal malalignment with associated coronal imbalance and pelvic incidence (PI)—lumbar lordosis (LL) mismatch. Methods A 16-year-old female patient presented with low back pain and right leg pain. Standing anteroposterior X-ray showed scoliosis with a Cobb angle of 34º and 5.7 cm of coronal imbalance. Lateral X-ray showed a sacralized L5 with a PI of 85º and LL of 47º. Pedicle subtraction osteotomy through the sacralized L5 addressed the malalignment secondary to a high PI-LL mismatch of 38º. Results Following alar resection, an osteotomy was performed below the L5 pedicles. The cranial parts including the superior endplate and intervertebral disc were removed. Osteotomy closure was achieved using the central rod technique. L5 incidence was reduced from 59º to 33º with reduced coronal malalignment. Back pain was significantly improved and PI-LL mismatch was improved to 10º two years post-operatively with no local loss of sagittal correction. Conclusions A lumbosacral osteotomy at the lumbosacral junction is useful to improve high PI – LL mismatch in patients with abnormally high PI with compensatory lumbar hyperlordosis.