Lightning Podiums: Adult Spinal Deformity - Room 801A

Presented by: R. Haddas

Author(s):

R. Haddas(1), I. Lieberman(2)

(1) Texas Back Institute, Research Foundation, Plano, TX, United States
(2) Texas Back Institute, Plano, TX, United States

Abstract

Objective: To quantify the extent of change in sway associated with maintaining a balanced posture within the cone of economy (COE), in a group of adult degenerative scoliosis (ADS) patients' pre and post-surgery.

Background Context: Balance is defined as the ability of the human body to maintain its center of mass (COM) within the base of support with minimal postural sway. Sway is the movement of the COM in the horizontal plane when a person is standing in a static position. Spinal deformities comprise a variety of conditions that affect the normal spinopelvic alignment in the coronal and or sagittal planes. A variety of postural changes in the spine, pelvis and lower extremities are observed in ADS patients in their effort to compensate for the anterior shift in the gravity line. The ability of the human body to maintain the COM within the COE with minimal energy expenditure results from a complex interaction of supra- and infra-pelvic alignment parameters. These parameters are influenced by the flexibility of the spine and joints of the lower extremities, neuromuscular control, muscle strength, muscle endurance, and body habitus.

Methods: Fourteen ADS patients performed a series of functional balance tests a week before (Pre) and 3 months after (Post) surgery. The functional balance test was similar to a Romberg´s test in which the patients are required to stand erect with feet together and eyes opened in their self-perceived balanced and natural position for a full minute. All test subjects were fitted with 51 external reflective markers. Three-dimensional kinematic data was recorded at 100Hz using a 10 camera Vicon Video system. To establish the COE boundaries we first measured and then calculated the COM (middle COE ring) and head (top COE ring) displacements in the sagittal and coronal planes during the functional balance test using a custom algorithm. We further measured and calculated total sway amount by the overall length of the COM and head displacement line in the horizontal plane in all directions. Repeated measurements ANOVA was used to determine differences on COE dimensions and total sway during a balance test before and after surgical intervention.

Outcome Measures: COM and head sway in the sagittal and coronal planes and total sway amount.

Results: Surgical alignment statistically reduced COM total sway amount (Pre: 28.33 cm vs. Post: 22.07 cm; p=0.050), head sway in the sagittal direction (Pre: 1.10 cm vs. Post: 0.64 cm; p=0.041), and the base of support width (Pre: 0.33 cm vs. Post: 0.28 cm; p=0.047). Although they were not statistically significant, there was a trend toward smaller COM and head sway and displacements.

Conclusions: Surgical alignment in ADS patients reduced the sway and increased balance within the cone of economy when compared to the pre surgery condition. While most of the balance research in deformity patients is done focusing on the sagittal plane and based on a static imaging, our study provides the first effort to evaluate sway and global balance within the COE as a dynamic test before and after surgical intervention.