L5 pedicle subtraction osteotomy: indication, surgical technique and specificities.

PURPOSE: To evaluate the radiographic, functional outcomes, complications and surgical specificities of L5 pedicle subtraction osteotomy for fixed sagittal and coronal malalignment.

METHODS: A retrospective cohort of consecutive patients with prospectively collected data. Ten patients who underwent PSO at L5 were eligible for a 2-year minimum follow-up (average, 4.0 years). Patients were evaluated by standardized upright radiographs. Preoperative and postoperative radiographies, surgical data and complications were collected.

RESULTS: All surgeries were revision surgeries. The mean lumbar lordosis before surgery was - 22.5° (range, 8° to - 33°) and improved to - 58.5° (range, - 40° to - 79°). The sagittal vertical axis demonstrated a preoperative mean sagittal malalignment of 13.7 cm (range 3.5 to 20 cm), with correction to 4.6 cm postoperatively. Three patients required additional surgery at the latest follow-up for rod breakage.

CONCLUSIONS: PSO of L5 can be a safe and effective technique to treat and correct fixed sagittal imbalance and provide biomechanical stability. The high complication rate mandates a careful assessment of the risk/benefit ratio of such a major surgery. Most patients are satisfied, particularly when sagittal balance is achieved.