The Possibility of the Activation of the Abductor Hallucis Muscle as a Result of the Toe-spread-out Exercise in Patients With Hallux Valgus and in People Without the Deformity: Clinical Trial.

The study design was based on an interventional model (clinical trial). The participants were assigned to two research groups (A - with diagnosis of hallux valgus and B- without the deformity) that received therapeutic intervention of the TSO exercise performed unilaterally. The unexercised feet could have caused a synergistic effect and falsified the results, thus the unexercised feet were excluded from the control group. Nevertheless, a small control group which did not undergo any hallux therapy was created to check if any changes in analysed parameters are actually related to the intervention. These control group patients were examined twice at an interval of 14 days.

The hallux deformities were assessed on the basis of X-ray images taken in weight-bearing conditions, in a standing position in the anterior-posterior projection. On all X-rays the hallux valgus angles (HVA) and the first intermetatarsal angles (FIA) were designated and measured by one radiologist.

Additionally, each patient with hallux valgus was assessed according to the Hallux Metatarsophalangeal-Interphalangeal scale (HMP-IP scale) developed by the AOFAS (American Orthopaedic Foot and Ankle Society).

The effects of the exercises were assessed using a comparison of the outcomes of two examinations: before and after therapy (research group A and B). For this purpose, a surface electromyographic examination (sEMG) recorded from the abductor hallucis (AbdH) muscle was performed. The following parameters of electromyography were analysed in three phases of TSO exercise: amplitude and frequency pattern. Additionally, the motor fibres of the tibial nerve and the sensory fibres of the sural nerve function in electroneurographic examination (ENG) and range of motion of hallux using goniometer were assessed.

The sEMG recorded from the AbdH muscle and the ENG were performed with the use of the KeyPoint System (Medtronic A/S, Skovlunde, Denmark) and appropriate to the type of neurophysiological studies and set of electrodes (surface electrodes, bipolar stimulating electrode, and grounding electrode).