Anterior Column Realignment (ACR) in Adult Sagittal Deformity Correction: Technique and Review of the Literature

Study Design. The anterior column realignment (ACR) procedure was retrospectively reviewed. Objective. To review surgical technique, complication avoidance, case examples, and published results on ACR. Summary of Background Data. For surgical correction of sagittal imbalance, three column osteotomies (3CO) have traditionally been employed for large degrees of correction at a single segment. However, 3CO procedures are technically challenging and carry high morbidity rates. ACR was developed as a less invasive procedure for restoring segmental lordosis. Methods. The ACR surgical technique is reviewed. ACR involves either a lateral, trans-psoas or anterior retroperitoneal approach to sectioning the anterior longitudinal ligament/annulus and placing a hyperlordotic cage. ACR usually also involves a second stage posterior column osteotomy. Three case examples are presented. A review of literature on ACR papers was completed. Results. Twelve papers met inclusion criteria. Ten to 27° of segmental lordosis were reported with use of hyperlordotic cages. 19° increase in mean intradiscal angle was reported when ACR was combined with posterior column osteotomy, 13° more than lateral lumbar interbody fusion alone without a hyperlordotic implant. Reported complication rates ranged from 18 to 47%. The most common minor complications were transient hip flexion weakness (9.3%) and transient paresthesia or dysesthesia (12%). There were few reports of major complications, such as bowel perforation (n = 1) or vascular injury (n = 1). Motor deficit was reported in 11 of 75 cases, lower than reported rates for 3CO. Conclusion. ACR is an emerging, less invasive technique for correction of sagittal deformity ACR has similar restorative capacity as other techniques with same or lower complication rates. Level of Evidence: 4