Efficacy of Botulinum Toxin Injections in the Rectus Femoris to Treat Stiff Knee Gait Following Acquired Brain Injury

Overview

Stiff knee gait is a common gait dysfunction following acquired brain injury. This gait deviation is characterized by reduced knee flexion during swing phase of the gait cycle and adversely impacts safe foot clearance. Stiff knee gait is an inefficient gait pattern and slows walking speed, limiting one's ability to adapt walking to community mobility demands. Fall risk is increased with this gait problem due to low or ineffective foot clearance. Common compensatory strategies are employed, such as circumduction, hip hiking or vaulting, during ambulation. The purpose of this study is to examine both the immediate (one month post-injection) and longer-term (4 months post-injection) effects of botulinum toxin injections to the rectus femoris (RF) on gait function in persons with brain injury. This study is clinically important to help inform rehabilitation professionals regarding treatment decisions for management of inefficient and often unsafe stiff knee gait problems following brain injury. Research Questions: * Is there a statistically significant difference in mean peak knee flexion between the experimental and control group? * Is there a statistically significant difference in mean peak knee velocity during the preswing and initial swing phases of gait between the experimental and control group? * Is there a statistically significant difference in gait function (based on 6-Minute Walk time and temporal distance measures) between the experimental and control group?

Pathophysiologic factors that may contribute to stiff knee gait in persons with brain injury are muscle hypertonicity of the quadriceps muscles, hip flexor weakness, and over activity of the gastrocsoleus muscles in terminal stance(1). Kerrigan et al (2) reported that hyperactivity of the Rectus Femoris (RF) during swing phase was a key contributor to this dynamic swing phase deficit in adults with spastic paresis. Overactivity of the RF muscle during early swing phase has also been identified as a major contributor to stiff knee gait dysfunction in children with cerebral palsy (3). Recognition of the role of RF over-activity in stiff knee gait in the cerebral palsy population has led to surgical and medical interventions aimed to minimize this constraint on swing phase mechanics, such as RF transfers, RF release, and Botulinum toxin injections (BTX-A)(4,5). Research in the cerebral palsy population supports the application of these interventions to improve knee flexion during swing phase and improve overall gait function and efficiency (6). The applicability of these directed interventions for stiff knee gait, particularly the less invasive BTX-A injections to RF, has not been well examined in adults with spastic paresis. Two research groups (7,8) examined the immediate effects of a motor branch block of RF in persons post-stroke with stiff knee gait and reported improved maximum knee flexion and mean knee flexion velocity during preswing and swing phase following the block. Very few studies9,10 to date examined the short-term effects of BTX-A injection to RF on gait function and energy cost during walking in persons post-stroke who ambulated with stiff knee gait. Stoquart and colleagues9 found that at two months following BTX-A injections, subjects had improved maximum knee flexion during swing phase and improved knee flexion velocity during toe off. Energy cost improved only in that subset of subjects who had greater than 10 degrees of knee flexion during swing phase prior to BTX-A injections. The results of this prospective observational study provided initial support for the efficacy of BTX-A intervention for stiff knee gait in adults post-stroke, however, the authors only examined the short-term effects of this intervention(9). Also, this study had limitations in its methodology, as gait function pre- and post-BOTOX® intervention was assessed using an automated treadmill as opposed to gait analysis during overground walking at self selected gait speed. Further research is needed to determine if there is longer-term benefit of BTX-A injections to RF on gait function in the brain injury population. Research Design: * Double-blind randomized controlled trial * Subjects will be randomly assigned to experimental or control group * The experimental group will receive BTX-A injection to rectus femoris (RF) followed by usual care * The control group will receive saline injection to RF followed by usual care * Subjects and researchers will be blinded to group assignment * Three-dimensional computerized gait assessments will be conducted pre-treatment (within 2 weeks prior to BOTOX®/placebo injection), 1 month post and 4 months post-injection