Objective: To study the effect of botulinum toxin type A (BTX-A) injection in the rectus femoris on the decreased knee flexion during the swing phase of gait (stiff-knee gait) in people with stroke.
Design: Intervention study (before-after trial) with an observational design.
Setting: Outpatient rehabilitation clinic and gait laboratory.
Participants: Nineteen chronic hemiparetic adults presenting with stiff-knee gait.
Intervention: Injection of 200 U of BTX-A (Botox) into the rectus femoris.
Main outcome measures: Before and 2 months after BTX-A rectus femoris injection: Stroke Impairment Assessment Set (SIAS), Duncan-Ely test, and an instrumented gait analysis.
Results: Median SIAS score improved from 53 (range, 36-65) to 57 (range, 42-70) (signed-rank test, P=.005) and the Duncan-Ely score from 3 (range, 1-3) to 1 (range, 0-3) (P<.001). In gait analysis, mean (+/- standard deviation) maximum knee flexion improved from 26 degrees +/-13 degrees to 31 degrees +/-14 degrees during the swing phase (paired t test, P<.001), knee flexion speed at toe-off improved from 82 degrees +/-63 degrees to 112 degrees +/-75 degrees/s (P=.009), and knee negative joint power (eccentric muscular contraction) improved from -.27+/-.23 to -.37+/-.26 W/kg (P<.001). The 4 patients who almost did not flex the knee (<10 degrees) before the BTX-A rectus femoris injection did not improve after the injection. The other 14 patients who flexed the knee more than 10 degrees before the BTX-A rectus femoris injection decreased the walking energy cost from 5.4+/-1.6 to 4.6+/-1.3 J x kg(-1) x m(-1) (P=.006).
Conclusions: BTX-A rectus femoris injection may be beneficial in patients with a stiff-knee gait after stroke, particularly in patients with some knee flexion (>10 degrees).