Effectiveness of Foot Biomechanical Orthoses to Relieve Patients Suffering from Plantar Fasciitis: Is the Reduction of Pain Related to Change in Neural Strategy?

Plantar fasciitis is a cause of chronic pain under the heel and bottom of the foot. One of the treatments to reduce pain consists of using plantar orthoses to address specific imbalances during foot placement or gait. The aim of the present study was to determine if reduction of pain with a treatment based on plantar orthoses is related to changes in reflexes and muscle activity of the muscles of the lower limbs. Ten patients (51.0±3.5 years, 76.0±2.38 kg, 171.9±1.8 cm, 3 women and 7 men) with plantar fasciitis for less than 1 year were followed up during nine weeks. Soleus M, H, and V waves recorded at rest and during voluntary contraction and Root Mean Square-Electromyogram from four leg muscles recorded during walking and static position were analyzed in patients before and 3, 6, and 9 weeks after wearing orthoses. Pain level and gait and posture parameters were also analyzed. Results were compared to five healthy participants exhibiting no pain (30.6±2.1 years, 60.0±3.5 kg, 167.0±3.4 cm, 3 women and 2 men). Results indicated that pain was significantly reduced after 3 weeks. H(max)/M(max) and H(sup)/M(sup) ratios were significantly higher and M(Hmax)/M(max) and M(Hsup)/M(sup) were significantly lower in healthy participants compared to patients with plantar fasciitis. No difference in the V/M(sup) ratio was found between groups. Furthermore, all other measured locomotor, stabilometric, and electromyographic parameters remained unchanged throughout the entire protocol. The reduction of pain is not related to change in neural activity suggesting that, after 9 weeks of wearing plantar orthoses, patients are not yet cured and return to physical activity should be delayed.