Effects of knee pain relief in osteoarthritis on gait and stair-stepping.

Osteoarthritic knee pain affects patient mobility. Relief of knee pain in osteoarthritis has been reported to increase loading of the knee during gait, but it is unknown whether such pain relief enhances knee loading during more demanding activities such as stair-stepping. The gait of 19 patients and stair-stepping of 14 patients with painful medial compartment osteoarthritis of the knee was assessed before and after pain-relieving intraarticular injection of the knee and compared with those of 21 healthy control subjects. There were significant increases in gait velocity, cadence, maximum external knee adduction moment (indicating increased loading in the medial compartment of the knee), and maximum external hip adduction and ankle abduction moments immediately after the injection. With the exception of velocity and ankle abduction moment, these variables were returned to levels that were not statistically different from those of the control subjects. However, no significant differences were found during stair-stepping in the external adduction-abduction moments about the knee, hip, or ankle after injection. Furthermore, the postinjection magnitudes of these variables during stair-stepping were significantly less than those of the controls. Therefore, although the relief of knee pain is sufficient to enhance gait function in osteoarthritis of the knee, it is insufficient to enhance stair-stepping function.