Bilateral lower limb strategies used during a step-up task in individuals who have undergone unilateral total knee arthroplasty

Objective. The purpose of this study was to determine how bilateral lower limb joint function is altered by the combined effects of osteoarthritis and its treatment by total knee arthroplasty. Design. Lower limb joint work of age-matched healthy, control participants was compared to surgical and non-surgical limb work in individuals who had undergone total knee arthroplasty. Background. Research investigating outcomes following total knee arthroplasty has focussed primarily on the surgical knee, identifying deficits in surgical knee function. The existence of additional lower limb deficits and adjustments made by unaffected joints to complement these deficits, has yet to be examined. Methods. Joint moments, power and work were calculated using bilateral lower limb force and kinematic data collected during a step-up to heights of 11.25 and 20 cm. Results. Fifty percent of patients were unable to step onto the 20 cm step. At both step heights, when the surgical limb led the step-up, surgical knee work was less than controls. When the non-surgical limb led, deficits in non-surgical lead knee work were observed. In both cases, lead hip work increased. Conclusions. Work done by both surgical and non-surgical knees in a step-up task was lower than that done by healthy controls. This deficit was balanced by increased lead hip extensor work.