Lower limb prosthesis users are known to be at a substantially increased fall risk compared to able-bodied individuals. The interaction between increased fall risk, reduced balance confidence and high prevalence of a fear of falling often leads to restricted mobility and loss of independence. Critically, the cause of these falls and the role that inherent balance plays in fall risk is poorly understood. This study proposes to identify key differences in balance and mobility between older below-knee prosthesis users and able-bodied individuals. By further understanding the differences between these groups and relationships between fall risk and various outcome measures, intervention techniques can be developed to improve functional balance. An improvement in upright balance will reduce the occurrence of falls and fall related injuries in this veteran population, as well as increase their participation in daily activities and improve their quality of life.

Previous studies have shown that persons with transtibial amputations (TTA) are at a substantially increased risk of falling as compared to able-bodied age-matched controls and have reduced confidence in their balance, both contributing to their restricted mobility and daily activity. This risk increases with progressing age, as aging affects musculoskeletal and somatosensory systems that are vital to controlling upright balance (i.e., maintaining the body center-of-mass (BCoM) within the limits of the base-of-support) and are already compromised in persons with TTA. An important consequence of elevated fall incidence is an increased risk of fall-related injuries that may lead to lost participation and independence. The effects of reduced sensory-motor function on upright balance in older adults has been extensively studied and led to development of effective assessment tools and intervention strategies to minimize fall risk. However, the dearth of similar studies and relatively poor understanding of the effects of additional complications from TTA on upright balance have significantly hampered progress towards addressing this important concern for Veterans with TTA. Consequently, this limits knowledge of predictive factors of falls among these prosthesis users and for informing therapeutic interventions that enhance functional balance. Therefore, the primary objective of this research is to develop an improved understanding of the sensory-motor mechanisms underlying upright balance and fall risk in older Veterans with TTA. The proposed study will compare differences between two age- and gender-matched groups: 1) older unilateral prosthesis users and 2) able-bodied controls.

Inclusion Criteria:

Inclusion criteria for the recruitment of subjects with below knee amputation include:

• Transtibial amputation
• Daily use of their clinically-prescribed prosthesis for ambulation without an assistive device
• Classified as Medicare Functional Classification Level K2- defined as a patient who "has the ability or potential for ambulation with the ability to traverse low-level environmental barriers such as curbs, stairs, or uneven surfaces - a typical community ambulator"
• Experience walking with a prosthesis for at least one year
• Residuum and amputated side in good condition (e.g., no adherent scars, lesions, ulcers, infections)
• Normal or corrected vision
• Able to walk a 10 m distance and stand quietly for 40 seconds without undue fatigue or health risk

Inclusion criteria for the recruitment of able-bodied controls include:

• Normal or corrected vision
• Able to walk a 10 m distance and stand quietly for 40 seconds without undue fatigue or health risk
• Suffered one or no falls in the previous 12 months

Exclusion Criteria:

Exclusion criteria for all recruited subjects (i.e., limb loss and control) include:

• Musculoskeletal (apart from amputation in the case of amputee subjects) and/or vestibular pathologies that would affect balance and/or stability
• Currently on medication that might affect proprioception and/or balance (e.g., drugs that are ototoxic, such as certain Aminoglycosides and pain killers)
• Cognitive deficits that preclude understanding of the instructions required to conduct the test

Older ambulatory individuals with or without unilateral below-knee amputation

12 months prospectively

Any untoward or unfavorable medical occurrence in a participant, including any abnormal sign (for example, abnormal physical exam or laboratory finding), symptom, or disease, temporally associated with the participant's participation in the research, whether or not considered related to the participant's participation in the research.