Usefulness of anterior column release for segmental lordosis restoration in degenerative lumbar kyphosis

Objective: Three-column osteotomies (3COs) for surgical correction of lumbar kyphosis show a strong correction capacity, but this procedure carries high morbidity rates. The anterior column release (ACR) technique was developed as a less invasive procedure. In this study the authors aimed to evaluate sagittal alignment restoration using ACR and to determine factors that affect the degree of correction.

Methods: This study included 36 patients (68 cases) who underwent ACR of more than one level for adult spinal deformity. Parameters for regional sagittal alignment included segmental lordosis (SL). The parameters for global sagittal alignment included pelvic incidence, lumbar lordosis, sacral slope, pelvic tilt, and sagittal vertical axis (SVA). In addition, the interdiscal height (IDH) and difference of interdiscal angle (DIDA) were measured to evaluate the stiffness of the vertebra segment. The changes in SL were evaluated after ACR and the change of global sagittal alignment was also determined. Factors such as the location of the ACR level, IDH, DIDA, cage height, and additional posterior column osteotomy (PCO) were analyzed for correlation with the degree of SL correction.

Results: Thirty-six patients were included in this study. A total of 68 levels were operated with the ACR (8 levels at L2-3, 27 levels at L3-4, and 33 levels at L4-5). ACR was performed for 1 level in 10 patients, 2 levels in 20, and 3 levels in 6 patients (mean 1.9 ± 0.7 levels per patient). Mean follow-up duration was 27.1 ± 4.2 months. The mean SL of the total segment was 0.4° ± 7.2° preoperatively and increased by 15.3° ± 5.5° at the last follow-up (p < 0.001); thus, the mean increase of SL was 14.9° ± 8.1° per one ACR. Global sagittal alignment was also improved following SL restoration with SVA from 101.9 mm to 31.4 mm. The degree of SL correction was correlated with the location of ACR level (p = 0.041) and was not correlated with IDH, DIDA, cage height and additional PCO.

Conclusions: This study demonstrated that the mean correction angle of SL was 14.9 per one ACR. The degree of disc space collapse and stiffness of segment did not affect the degree of correction by ACR.