General Session: Biomechanics
Presented by: R. Haddas - View Audio/Video Presentation (Members Only)
R. Haddas(1), I. Lieberman(2)
(1) Texas Back Institute, Research Foundation, Plano, TX, United States
(2) Texas Back Institute, Plano, TX, United States
Patients with adult degenerative scoliosis demonstrate an altered gait pattern. Such differences include decreased step length and reduced range of motion in the upper and lower extremities, asymmetry of trunk rotation and altered ground reaction forces. Spinal alignment surgery has been shown to improve function and quality of life as assessed by disease specific and generic health clinical outcome questionnaires. The purpose of this study is to evaluate the biomechanics of the lower extremities and spine during gait in patients with adult degenerative scoliosis before and after surgical intervention. Five subjects with symptomatic degenerative scoliosis who have been deemed appropriate surgical candidates underwent clinical gait analysis the week before surgery (Pre), one month (Post 1) and three months (Post 3) after surgery. Fifty-one reflective markers were incorporated to collect full body three-dimensional kinematics using 10 cameras. Ground reaction forces (GRFs) were measured using three parallel force plates. The patients walked at his/her self-selected speed along a 10 m walkway. Clinical gait analysis parameters were calculated from kinematic and kinetic data: these included spatiotemporal parameters, lower extremity and spine joint angle values at initial contact, as well as range of motion (ROM) and peak GRF. The data was analyzed with one way ANOVA with Bonferroni Post Hoc analyses to determine differences in walking patterns between times. Spinal alignment surgery improved the gait pattern in these adult deformity patients. A significantly faster walking speed (Post 1: 0.55 vs Post 3: 0.81 m/s p< 0.017) and cadence (Post 1: 71.59 vs Post 3: 96.28 steps/min p< 0.010) was measured at the three month post-surgery test in these patients in comparison to their pre-surgery and one month post-surgery data. Step time (Pre: 0.71 vs Post 1: 0.90 s p< 0.049; Post 1: 0.90 vs Post 3: 0.64 s p< 0.010) and stride time (Pre: 1.41 vs Post 1: 1.76 s p< 0.042; Post 1: 1.76 vs Post 3: 1.25 s p< 0.007) increased at one month after surgery, but dramatically decrease at three months after surgery. A diminished ankle eversion angle at initial contact (R Pre:6.90 vs Post 1:-5.41 deg p< 0.047; L Pre:6.93 vs Post 1:-5.91 deg p< 0.012) and more substantial neck side flexion ROM (Pre:1.77 vs Post 3:2.83 deg p< 0.031) was seen pre-surgery versus post-surgery. Pelvis ROM in the sagittal plane (Pre:2.67 vs Post 1:5.57 deg p< 0.050; Post 1:5.57 vs Post 3:2.30 deg p< 0.045) was found to be increased one month after surgery, but did decrease at three months after surgery. Peak GRF was seen to be lower (Pre:610 vs Post 3:311 N p< 0.050) post-surgery. Based on our preliminary results, surgical correction of spinal alignment on adult deformity patients improved spatiotemporal parameters, lower extremity and spine function and GRF. Clinical gait analysis reveals significant differences before and after spine surgery. Our results presented little or no improvement one month after surgery, but dramatic improvement three months after surgery. This may imply a rehabilitation effect or a post-operative pain inhibition effect. Formal gait and motion analysis can provide a true and consistent objective method to assess the impact of spinal deformity on function and changes after treatment.