Corner Osteotomy as the more Advanced Approach to Deformity Correction in Adult Spinal Deformity: A Retrospective Comparative Study Between Two Osteotomy Techniques.

Study Design: A retrospective study.

Objective: To investigate the usefulness of corner osteotomy (CO) in patients with adult spinal deformity (ASD) by comparing with pedicle subtraction osteotomy (PSO) for lordosis correction.

Summary Of Background Data: PSO remains a valuable procedure for patients with ASD, but it has a limit to obtaining correction angles exceeding 45° in patients with a large pelvic incidence or with previous spinal fusion surgeries. Theoretically, CO can exceed the limitation of PSO and can achieve a wide range of correction angles. However, no study has analyzed the clinical data and usefulness of CO.

Methods: This study included 115 patients (mean age 71.1 y, mean follow-up period 78.9 mo) with ASD who underwent deformity correction using PSO or CO. Comparative analysis was performed on spinopelvic parameters including segmental angle (SA) around the osteotomy site, and clinical and surgical assessment between the PSO and corner groups.

Results: In the corner group, the postoperative SA (35° vs. -39.3°, P=0.004) and the degree of SA correction (34.8° vs. 39.7°, P=0.004) were greater, and a broader range of SA correction was also possible (18-51° vs. 18-61°). Although the operative time was longer in the corner group (316.8 min vs. 342.3 min, P=0.014), the estimated blood loss (EBL) was lower (2841.3 mL vs. 2465.4 mL, P=0.032). There was no difference in major complication rates, but the frequency of rod fracture (RF) was lower in the corner group (36/27 vs. 1/51, P<0.05).

Conclusion: CO showed a greater SA correction and achieved a broader range of SA correction angles than PSO with no difference in the incidence of major complications. In addition, the EBL and the frequency of RF were lower. Based on these results, we expect that CO can serve as a promising surgical alternative to PSO for spinal deformity correction among patients with ASD.