The Toe-spread-out Exercise in Patients With Hallux Valgus and Without the Deformity
Condition: Hallux Valgus
MeSH terms: Hallux Valgus; Bunion
Study type: Interventional

Summary: 
      The effectiveness of conservative treatment of hallux valgus deformity has not been
      sufficiently explored yet. The aim of this study was to assess the effect of the
      toe-spread-out exercise on the amplitude and frequency pattern in a surface electromyographic
      examination in patients with hallux valgus and in people without the deformity. An additional
      objective is the assessment of nerve conduction in an electroneurography and the assessment
      of range of motion in a clinical examination.
    

Detailed description: 
      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).

      For the analysis of the bioelectrical activity of the AbdH the standard disposable Ag/AgCl
      surface electrodes with an active surface of 5mm2 were applied. The active electrode
      (cathode) was located on the belly muscle and the reference electrode (anode) was attached 3
      cm distally from the active electrode. For the purpose of the sEMG examinations, the time
      base on 80ms/D and sensitivity of the recording of 0.5mV/D were set. 10kHz upper and 20Hz
      lower filters of the recorder amplifier were used.

      The sEMG recordings were performed during three phases of the TSO exercise. The following
      parameters were analysed: amplitude of motor unit action potential (MUAP) measured in mV, and
      the frequency pattern of the MUAP recruitment of AbdH muscle activity. The sEMG tests with
      maintaining each phase of the TSO exercise were performed three times in order to obtain more
      objective results. The first test was treated as a training trial. The other two were taken
      into account to assess the amplitude and the frequency pattern. Only the trial with the
      highest amplitude and the most interference pattern was analysed as the result of the most
      effective recruitment of the MUAPs. The minimal and maximal amplitude values were
      automatically measured by the KeyPoint System after the marking of the MUAP amplitude peaks.
      An 'on-line' evaluation of the frequency of the MUAP recruitment during a maximal muscle
      contraction was a subjective visual assessment made by one experienced neurophysiologist. It
      was based on the following classification patterns presented by Buchthal et al. and by
      Stalberg and Falck: interference, intermediate, poor, and straight.

      In the ENG the following parameters of the CMAP (compound muscle action potential) from the
      tibial nerve and of the SNAP (sensory nerve action potential) from the sural nerve were
      analysed: amplitude (measured from a negative inflection to the baseline in mV or in µV),
      latency (measured in ms) and conduction velocity (measured in m/s). During the ENG the time
      base on 5ms/D and sensitivity of the recordings on 2mV/D were set. 10Hz upper and 10kHz lower
      filters of the recorder amplifier were used. In order to record the compound muscle action
      potentials (CMAP) evoked from the AbdH muscle, the same location of surface electrodes as in
      the EMG was used. The electrical stimulation of the tibial nerve was applied in two points:
      below the medial malleolus and in the popliteal fossa. The ground electrode was located in
      the plantar part of the foot. Single rectangular stimuli with duration of 0.2ms were
      delivered via bipolar electrode at 1Hz frequency while their intensity ranged from 30mA to
      the value evoking the supramaximal CMAP. For recordings of SNAP from the sural nerve
      antidromic and repetitive electrical stimulation with an intensity of 20 mA was required.
      Recording electrodes were placed near the lateral malleolus while the stimulation point was
      15 cm proximally at the external border of the Achilles tendon.

      A clinical examination with the use of a goniometer was performed in the supine position of
      the patient. The investigator measured the range of the motion of the plantar and dorsal
      flexion in the first metatarsophalangeal joint and plantar flexion in the hallux
      interphalangeal joint.
    

Intervention name(s): toe-spread-out exercise
Intervention type(s): Other
Intervention description(s): The therapeutic intervention lasted 14 days and focused on doing the TSO exercise. This exercise was performed unilaterally under the supervision of a qualified physiotherapist. The starting position of the TSO exercise was the sitting position with the knee joint and hip bent at 90 degrees. The exercise consisted of 3 consecutive phases: dorsiflexion of the toes keeping the metatarsal heads and the heel on the ground, moving the fifth toe down and in a lateral direction, moving the big toe down and abduction. The final position needs to be maintained for 5 seconds. The whole sequence was repeated 200 times a day.
Allocation: Non-Randomized
Intervention model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Treatment
Keywords: hallux valgus,; toe-spread-out exercise; abductor hallucis muscle; surface electromyography