Abstract
Postural stability (PS) is closely associated with quality of life and falls in the elderly. Recent work has demonstrated impaired gait and increased falls in patients with ASD, suggesting impaired postural stability due to biomechanical constraints of the spinal deformity. However, while previous studies have investigated the effect of spinal malalignment on static balance, no previous work has specifically focused on postural stability or dynamic balance in patients with ASD, nor the sensorimotor contribution to instability. Computerized dynamic posturography (CDP) is a widely used diagnostic and prognostic tool for assessment of postural instability in diseases of gait and imbalance such as Parkinson's disease, osteoarthritis, and vestibular dysfunction.
The objective of our study was to assess postural stability of patients with adult spinal deformity (ASD) using cCDP and (1) compare with published normative controls, (2) determine the relationship between fall status and postural stability, and (3) determine the relationship between quality of life and postural stability in ASD
Prospective analysis of postural stability using CDP.
Eleven consecutive patients with severe adult spinal deformity who were seen and evaluated in an outpatient clinic.
Equilibrium scores (ES) during Sensory Organization Testing (SOT) across 6 conditions with varying sensorimotor deprivation, motor latency during Motor Control Testing (MCT), and a history of falls in community setting.
Eleven patients with ASD were prospectively enrolled. Inclusion criteria: coronal cobb (CC)≥20°, Pelvic incidence-lumbar lorodsis (PI-LL) >10°, sagittal vertical axis (SVA) ≥5 cm, pelvic tilt (PT)≥25°, and thoracic kyphosis (TK)≥60°. Exclusion criteria: inability to stand, presence of confounding neurological conditions. PS was determined using two randomly assigned tests with CDP: (1) SOT to evaluate the voluntary use of sensory information; and (2) motor control test (MCT) to assess involuntary postural reactions in response to external perturbations. Patient performance was compared to age-gender matched controls. QOL metrics included SRS-22 and SF-36
Mean age was 65±4.6, and 6/13 (46%) were female. Mean PI-LL was 31.2±12.7, PT 32.8±8.0, SVA 11.8±6.3 cm, TK 27.3±16.6, and CC 14.5±16.7. Four patients reported falling in the previous 6 months (36%). Those patients who self reported falling in past 6 months demonstrated significantly lower SOT (Conditions 2–6, p<.04) and SRS scores (p=.003). ASD patients demonstrated significantly lower SOT scores (Conditions 2–6, p<.03), and greater latency of limb reaction time during backward translation (p=.0379) compared to age-matched controls-consistent with a higher global instability and elevated risk of falls. Mediolateral sway (predictor of falls) was correlated with TK in the eyes open and eyes closed conditions (p<.04).
ASD patients demonstrate impaired postural stability and dynamic balance compared to normal controls. Further, postural stability and QOL metrics correlated with self-reported falls. These findings suggest that ASD patients have drastically altered balance, which predisposes these patients to elevated risk of falls and injury as well as decreased ambulatory confidence and quality of life.