Biomechanical and psychological factors that distinguish fallers from non-fallers : a comparative study of transtibial amputees and able bodied individuals

Transtibial amputees are at a higher risk of falling than age-matched able-bodied individuals. In order to make recommendations for falls prevention and treatment programmes, it is important to have a sound understanding of the underlying biomechanical function in persons at high risk of falling. While biomechanical differences between fallers and non-fallers have been identified in older adults, no research to date has specifically compared amputee fallers and non-fallers. The aim of this thesis was to undertake a biomechanical comparison of amputee and able-bodied fallers and non-fallers performing activities of daily living. A secondary aim was to investigate the effect of falls on balance confidence and quality of life and to determine whether a relationship existed between functional and psychological measures according to a person’s falls history. Twenty participants (11 transtibial amputees and 9 controls) took part in several studies including a kinematic and kinetic analysis of level walking, stair ascent and descent using a 3-step staircase. They also completed the Sensory Organisation Test (SOT) and Motor Control Test (MCT) on the NeuroCom EquiTest and their postural control was measured in static and dynamic conditions. Participants completed the MFES and SF-36 psychological instruments aimed at quantifying balance confidence and perceived quality of life, respectively. The first study investigated how falls were monitored by physiotherapists and the use of outcome measures in amputee rehabilitation in England. Shortcomings were identified in amputee rehabilitation in that physiotherapists did not monitor falls incidence regularly among their amputee patients and that there was no consensus on the types of recommended outcome measures. The second study explored the biomechanical differences between fallers and non-fallers during level walking and the findings indicated that the amputee fallers had a significantly larger vertical GRF with respect to body weight during loading on the affected limb (p=0.01) and consequently loaded their affected limb significantly more than the non-fallers (p = 0.03). The opposite finding was reported in the control group, where the non-fallers had significantly greater load rates compared to the fallers (p=0.02). The amputee fallers also had significantly different power profiles at the hip (power absorption in stance, p=0.01) and the ankle (power generation in pre-swing, p=0.04) during the transition from double to single support on the affected leg. In the third study, biomechanical differences were examined during stair ascent revealing that the fallers walked significantly faster up stairs than the non-fallers (p=0.05) in the amputee groups, while the opposite was observed in the control groups (p=0.03). Kinematic differences were revealed, such as significantly increased knee ROM in both groups of fallers when compared to their non faller counterparts (p=0.04 and p=0.05 for the amputee and control groups, respectively). The amputee fallers had significantly larger vertical GRF peaks (p=0.01 and p=0.00, respectively), decay rate (p=0.01), ankle plantarflexor moment (p=0.01) and knee joint powers (power absorption in pre- and mid-swing, p=0.00 and p=0.01, respectively) on the intact limb compared to the non-fallers. A forth study exploring gait patterns during stair descent revealed that some amputees used a modified stepping strategy during stair locomotion by adopting a ‘step to’ pattern. The fifth study used computerised dynamic posturography with the Neurocom Equitest to understand how fallers and non-fallers maintained postural control under static and dynamic conditions. The results demonstrated that the amputee fallers scored significantly better on the equilibrium score on the SOT when visual and somatosensory input was inaccurate (p=0.05) (indicating less postural sway). The amputee fallers also bore significantly more weight through their affected limb during destabilising backwards and forwards translations, while the amputee non-fallers bore more weight through their intact limb (