Neural factors, such as spasticity, or an increase in the sensitivity of the myotatic reflex, can contribute significantly to calf muscle stiffness. Likewise, non-neural factors, such as immobilization and age-induced changes in the mechanical properties of muscle and connective tissue, are known to increase resistance to joint movement and to contribute to the limited DF-PROM. Both neural and non-neural factors can impair ankle motion, resulting in balance impairments during standing or gait. Limited DF-PROM can alter foot positioning in weight bearing, resulting in hyperextension of the knee, and decreased ability to shift the center of gravity (COG) during standing and gait. A variety of interventions, such as stretching and joint mobilization, have been attempted to attenuate the effects of limited DF-PROM and to reduce further deterioration in patients post stroke. Both stretching and joint mobilization have been proven effective for improving ankle passive range of motion in patients with stroke; however, there is a limit to the durability of the effect and improvements in functional ability. For this reason, improvements in joint range of motion (ROM) must be accompanied by gains in muscle strength to improve functional ability. This is especially true for patients with hemiplegia who are not capable of weight bearing symmetrically and require additional training, including repetitive and continuous weight bearing on the paretic lower limb.
Adequate ankle motion for normal gait ranges from 10° to 15° of dorsiflexion passive range of motion (DF-PROM) to allow the tibia to move over the talus. However, limited ankle mobility is a common impairment in patients with stroke whose DF-PROM has been shown to be approximately half of that in healthy subjects. As a result, these patients have impaired dynamic balance in standing or gait. Mulligan first proposed mobilization with movement (MWM) as a joint mobilization technique. Talocrural MWM to facilitate DF-ROM is performed by applying a posteroanterior tibia glide over a fixed talus while the patient actively moves into a dorsiflexed position while standing. Talocrural MWM has been applied to chronic ankle instability and has been proven effective in improving DF-PROM and standing balance. Subtalar MWM to facilitate DF-ROM is performed by bringing foot to dorsiflexion-abduction-eversion by flexing patient' knee.
The effects of subtalar MWM have not been investigated in patients with stroke. Therefore,the purpose of the present study is to examine the effects of subtalar MWM on muscle strength, balance, functional performance, and gait parameters in patients with chronic stroke.
