A comparison of dynamic stability between total hip arthroplasty individuals and healthy older adults during walking

Dynamic stability is required during walking to control the body's mass over the oscillating lower limbs. A loss of stability for an older individual could result in a fall leading to decreased mobility or even death. The center of mass (COM) of the body must be controlled over a narrow base of support (BOS), and the size of the BOS changes as the individual walks. This study included 32 volunteers ages 65 to 85. Dynamic stability was examined in the medial-lateral direction during the two phases of walking known as single limb support (SLS) and double limb support (DLS). SLS occurs when one foot is in contact with the ground, and DLS occurs when two feet are in contact with the ground. Sixteen individuals with total hip arthroplasty (THA) and 16 age-matched controls were examined while walking at their self-selected speed.; The hypotheses examined within-group differences of side during the SLS and DLS phases. For the individuals with THA, the within-group comparison showed no differences in the operated and the non-operated lower limbs during both the SLS and DLS phases of walking Comparison of the right and left lower limbs showed no differences for the healthy older adults during the SLS phase. During the DLS phase of walking, the healthy older adults showed a slight lateral lean of the COM toward the leading limb side. Temporal-spatial walking parameters and dynamic stability during the DLS phase were different between the two groups. The individuals with THA had a slower velocity with a decreased stride length and decreased cadence in comparison to the healthy older adults. The pattern of dynamic stability during the DLS phase was to hold the COM in the midline during a longer DLS phase. These findings support the theory that individuals with THA have a different proactive control strategy for dynamic stability during the DLS phase of walking in comparison to healthy older adults.