Volitional Limits Of Stability Deficits In Individuals With Lower Limb Amputation

Postural stability in below-the-knee (BTK) amputees, due to sensorimotor impairment, is associated with an increased rate of falls and reduced participation in activities of daily living. Traditional, target-based Limits of Stability (LoS) testing of dynamic balance has revealed reduced sway amplitude, though volitional self-selected excursion (VLoS) has not yet been studied in this population. PURPOSE: Provide the known assessment of VLoS in individuals with BTK amputation. METHODS: Four male adults (age 32.7 ± 11.4 yrs) with BTK amputation, otherwise healthy, minimum one year prosthesis-users and independently ambulatory, completed testing. Testing included two trials of VLoS, alongside completion of the Activities-Specific Balance Confidence (ABC) Scale. The ABC measures perceived confidence in performing daily tasks without becoming unsteady. For the VLoS protocol, participants moved their center of pressure about their base of support to maximal limits without lifting feet off a force plate measuring device. Overall and quadrant areas (cm2) from the second VLoS trial were considered. Pearson correlation tested the relationship between overall VLoS and ABC. Comparison of rear quadrant areas, prosthetic (PR) and non-prosthetic (NP) side, were conducted using paired t-tests. Due to the exploratory nature of this study, α was set to 0.10 to determine findings worth further exploration. RESULTS: A correlation (r = 0.92, p = 0.08) was found between the ABC scale and VLoS re-testing. Difference was found in back quadrant areas (PR = 24.5 ± 29.9, NP = 36.3 ± 36.9, p = 0.06). CONCLUSION: The correlation between the ABC and VLoS results may indicate the ability of BTK amputees to accurately assess their confidence in tasks that challenge dynamic balance. However, reduced area explored in the rear quadrant areas may indicate a lack of confidence in volitional movement in a rearward direction on their prosthetic side. Future studies are warranted to expand the overall knowledge of dynamic balance in BTK amputees.