Prospective Evaluation of Gait and Trunk Range of Motion (Rom) Following Anterior or Posterior Spinal Fusion in Adolescent Idiopathic Scoliosis (AIS)

Information provided by

Lawrence G. Lenke, MD

The Jerome J. Gilden Professor of Orthopedic Surgery

Co-Chief Pediatric & Adult Spinal, Scoliosis & Reconstructive Surgery

Keith Bridwell, MD

Orthopaedic Surgeon

Washington University School of Medicine

Introduction: Recently, several studies have compared the radiographic and clinical outcomes of thoracic AIS surgery on those patients undergoing anterior vs posterior fusion. However, comparison of functional outcomes have not been reported.

Purpose: To prospectively compare changes in gait and spine ROM between AIS patients undergoing either an anterior or posterior instrumented spinal fusion.

Methods: Thirty-one subjects with single or double thoracic (Lenke Types 1&2) AIS curves surgically treated (15 Posterior & 16 Anterior) were tested preop and at 24 months postop. Reflective markers were placed at right and left acromion processes, C7, S2 and right and left anterior superior iliac spines. A 6 camera video system recorded the patient's gait and trunk ROM during maximum lateral flexion, forward flexion and rotation. ANOVA procedures were used to assess changes between operative conditions and groups (p<0 .05).

Results: For the posterior group, the average preop thoracic curve was 59º (range 50º to 77º) and at 2-year followup was 31º(range 15º to 47º). For the anterior group, the preoperative main thoracic curve was 54º (range 40º to 82º), decreased to an average of 29º (range 18º to 42º) at 2-year follow-up. An average of 4 fewer levels were fused and the lowest instrumented vertebra was 1 level higher in the spine for the anterior group.

Results: (see table below) Gait results showed no change in gait speed and coronal and sagittal plane kinematics, regardless of group. Transverse plane motion during gait was reduced in both groups. Spinal ROM results indicated motion loss in all three planes (*p<.05), regardless of group with the Posterior group having less postoperative range of motion than the anterior group (^p<.05). Unlinking surgical approach from the number of fused levels and the lowest instrumented vertebra with a subset of subjects also indicated less postoperative ROM for the posterior group (p<.05).

Discussion: The radiographic results were similar for % correction obtained in both groups. The anterior patients were fused with fewer levels and overall slightly shorter than the posterior group. Gait results were unchanged between both groups and did not show any differences. ROM results favored the anterior approach over the posterior approach, however, it should be noted that both groups had decreased postoperative range of motion.

Conclusions: Although spinal ROM was decreased in both groups at 2 years postoperative, the anterior group had significantly more motion in their spine than the posterior group even after accounting for the lesser number of fusion levels by the anterior approach.