Roderick M Holewijn1, Idsart Kingma2, Marinus de Kleuver3, Noël L W Keijsers4. 1. Department of Orthopedic Surgery, VU University Medical Center, Amsterdam Movement Sciences, De Boelelaan 1117, Amsterdam, 1081 HV, The Netherlands. Electronic address: rm.holewijn@vumc.nl. 2. Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, De Boelelaan 1105, Amsterdam, 1081 HV, The Netherlands. 3. Department of Orthopedic Surgery, Radboud University Medical Center, Mailbox 9101, 6500 HB, Nijmegen, The Netherlands. 4. Sint Maartenskliniek Research, Sint Maartenskliniek, Mailbox 9011, 6500 GM, Ubbergen, The Netherlands.
Abstract
BACKGROUND CONTEXT: Patients with adolescent idiopathic scoliosis (AIS) perform surprisingly well after spinal correction and fusion. It was previously hypothesized that, during gait, certain mechanisms compensate for the loss in spinal motion. Still, previous studies could not identify such compensatory mechanisms in the lower body. PURPOSE: This study aims to test the hypothesis of a compensatory increased motion of the distal unfused part of the spine during gait after posterior spinal correction and fusion. STUDY: This is a prospective gait study. PATIENTS AND METHODS: Twelve patients with AIS were included. Sets of three VICON skin markers were used to measure the 3D motion of the proximal part of the fusion in relation to the pelvis (PFP) and the distal part of the fusion in relation to the pelvis (DFP). By doing so, PFP represents the motion of the fused and unfused parts of the spine, and DFP represents the motion of the unfused part of the spine. Measurements were performed preoperatively and 3 and 12 months after posterior spinal correction and fusion. RESULTS: Surgery resulted in a decrease in PFP transversal plane range of motion (ROM) (8.3° vs. 5.9°, p=.006). No compensatory increase in the ROM of DFP could be identified. Actually, DFP transversal plane ROM also decreased (8.2° vs. 5.6°, p=.019). No improvement over time was observed when comparing the 3- and 12-month postoperative measurements. CONCLUSIONS: The hypothesis of a compensatory increase in motion of the distal unfused segments after spinal fusion for AIS is a much researched and controversial topic. This study is the first to study this hypothesis in such detail during gait and could not demonstrate such increase.
BACKGROUND CONTEXT: Patients with adolescent idiopathic scoliosis (AIS) perform surprisingly well after spinal correction and fusion. It was previously hypothesized that, during gait, certain mechanisms compensate for the loss in spinal motion. Still, previous studies could not identify such compensatory mechanisms in the lower body. PURPOSE: This study aims to test the hypothesis of a compensatory increased motion of the distal unfused part of the spine during gait after posterior spinal correction and fusion. STUDY: This is a prospective gait study. PATIENTS AND METHODS: Twelve patients with AIS were included. Sets of three VICON skin markers were used to measure the 3D motion of the proximal part of the fusion in relation to the pelvis (PFP) and the distal part of the fusion in relation to the pelvis (DFP). By doing so, PFP represents the motion of the fused and unfused parts of the spine, and DFP represents the motion of the unfused part of the spine. Measurements were performed preoperatively and 3 and 12 months after posterior spinal correction and fusion. RESULTS: Surgery resulted in a decrease in PFP transversal plane range of motion (ROM) (8.3° vs. 5.9°, p=.006). No compensatory increase in the ROM of DFP could be identified. Actually, DFP transversal plane ROM also decreased (8.2° vs. 5.6°, p=.019). No improvement over time was observed when comparing the 3- and 12-month postoperative measurements. CONCLUSIONS: The hypothesis of a compensatory increase in motion of the distal unfused segments after spinal fusion for AIS is a much researched and controversial topic. This study is the first to study this hypothesis in such detail during gait and could not demonstrate such increase.