The Impact Of An Ankle Foot Orthosis On Gait Recovery In MS: Pilot Data

Background: Impaired muscle function is common in multiple sclerosis (MS) and can produce lower extremity weakness, resulting in difficulty walking.  Dorsiflexion weakness is especially common and often leads to the first sign of gait dysfunction in MS. This weakness is likely lesion-driven. However, it is possible that secondary weakness develops in the leg, particularly in calf muscle, as the result of faulty gait mechanics initiated by the dorsiflexion weakness. AFO prescription is common to address dorisflexion limitations in persons with MS. However, few studies have attempted to evaluate the impact of bracing on gait in MS and no consensus has been reached concerning benefit or optimal design. This study was designed to evaluate the effect of a hinged orthosis (Tamarack joint with adjustable check strap, TCS) on gait recovery in persons with MS.

Objectives: To investigate the impact of the TCS AFO on spatial and temporal gait parameters, electromyography (EMG), and walking endurance, in select individuals with MS.

Methods: This was a non-randomized, single group (N=15), repeated measures study.  The outcome measures for the study included: 1. Computerized gait analysis (GAITRite), 2. EMG of the anterior tibialis (AT), gastrocnemius (GN), and vastus lateralis (VL) muscles, 3. 6-Minute Walk Test (6MWT), and 4. 12-Item MS Walking Scale.  This study was 12 weeks long consisting of 5 training sessions and 3 testing periods.

Results: Preliminary gait analysis data on four subjects indicated a trend towards improvements in absolute step length and step length symmetry, stance symmetry, and gait velocity. Endurance was also markedly increased as measured by the 6MWT. EMG analysis revealed increased AT and GN activity with the AFO on vs. off. In addition, improved timing of the AT and GN was evident with the AFO on compared to no AFO. Also notable were marked improvements in perception of walking abilities as measured by the 12-Item MS Walking Scale.

Conclusions: Results from our preliminary analysis suggested that there is marked benefit of the TCS AFO on overall gait parameters, including step length and stance symmetry, as well as endurance. Patient perception of gait impairment was also less after use of the brace for the 12-week period. In addition, the orthosis design appeared to facilitate more typical muscle firing in the leg during gait, thus providing the opportunity for halting and potentially reversing the development of secondary weakness.