The reduction in quadriceps femoris muscle activation is considered to be one of the major mechanisms involved in pathological motion patterns in patients with osteoarthritis (OA) of the knee. These activation deficits are, at least in part, reversible after total knee arthroplasty (TKA). The purpose of this study was to investigate the effects of TKA on motion patterns in patients with OA of the knee.
50 patients with knee OA were investigated prior and at 33 +/- 8 months after unilateral TKA. The control group comprised 17 healthy volunteers matched to the study group with respect to age. The gait analysis was performed with an optoelectronic motion analysis system (Elite(R), Italian).
Step length, step duration and velocity increased after surgery (p < 0.05), but remained lower than the values of the controls (p < 0.05). Extension angles in stand and swing phase remained unchanged and significantly lower when compared to control values (p = 0.01, p = 0.04). Flexion angles in swing (p = 0.02) and stand phase (p = 0.01) increased on the operated side and were significantly higher than the flexion angle in the control group (p = 0.02, p = 0.03). Reextension in stand phase, which was investigated for quantification of functional range of motion, increased bilaterally after surgery (p < 0.01), but remained lower than the reextension of the controls (p </= 0.01).
Although a significant improvement of pathological motion patterns in patients with OA of the knee after unilateral TKA occurred, a deficit persisted 33 +/- 8 months after surgery. The improvement of functional range of motion in stand phase was only caused by increased flexion. No influence was found with gait analysis on extension after TKA.