Effectiveness of Strengthening Exercise Program Compare With Foot Orthoses in Patients With Plantar Heel Pain

Plantar heel pain (PHP), normally known as plantar fasciitis, is a common encountered musculoskeletal problem in the foot that can cause activities limitation, difficulty, and discomfort especially while standing and walking. It involves pain and inflammation of the plantar fascia, which runs across the bottom of the foot and connects the heel bone to toes. Approximately 10% of the American population have inferior heel pain in their lifetime, and 80% in these patients were diagnosed as the PHP.

According to Sullivan's study, they identified the musculoskeletal factors in PHP and found that the ankle evertors, peroneus brevis and longus muscles, and toe flexors, flexor hallucis longus and brevis muscles, flexor digitorum longus and brevis muscles were weaker than the normal. Moreover, previous studies reported that the patients with PHP frequently have weakness of the tibialis posterior muscle.

Since the presence of PHP involved with the deviation of lower-extremity biomechanics, foot orthoses have been the common intervention used as a part of the conservative treatment. The previous cadaveric study provided helpful information regarding the mechanism of foot orthoses; the researchers explained that foot orthoses could reduce plantar fascia strain during stance phase by lifting the medial longitudinal arch and decreasing abnormal foot pronation. Therefore, custom-fitted orthoses should be used to provide individual comfort, maintain the height of medial longitudinal arch, and also protect the excessive tensile strain of the plantar fascia.

Therefore, the present study interested to compare the effectiveness of home based strengthening exercise program and the low-cost CFO on pain intensity, foot function, and lower-extremity biomechanics during walking in patients with PHP.

PHP can be presented with a high prevalence in both athletic and non-athletic populations. Diagnosis of the PHP based on patients' history and physical examination. To obtain the correct diagnosis of the PHP, subjective and objective physical examinations should be performed.

PHP is believed that it occurs from the excessive cumulative strain of the plantar fascia enthesis or the insertion of the plantar fascia. This excessive strain resulted in repetitive microtrauma or inflammatory condition. Sullivan in 2015, studied musculoskeletal and activity factors that associated with PHP. The results showed that the impairments in patients with PHP have a high association with high body mass index (BMI), decrease in ankle dorsiflexion range of motion (ROM), and weakness of ankle evertors and toe flexors muscles. Therefore, these factors may have a high chance to induce the recurrence of PHP.

The PHP management could be approached either surgical or non-surgical treatment. The previous studies showed conflict and fewer evidences ineffectiveness of the treatment for PHP. Moreover, approximately 18 - 50% of patients with PHP who received conservative treatment still presenting their symptoms and pain in 2 years after diagnosis and 30% have recurrent PHP. From the above-mentioned review, there are few studies investigating the effect of strengthening exercise for the foot and ankle muscles on PHP.

The weakness of foot and ankle muscles may lead to recurrent symptoms of PHP due to insufficient muscle function, co-contraction of muscles, and foot joints position during walking. Thus, peroneus brevis and longus muscles, tibialis posterior muscles, flexor hallucis longus and brevis muscles, flexor digitorum longus and brevis muscles should be strengthening.

As described in American clinical practice guideline, customized foot orthoses (CFO) could be used to provide short-term management (3 months) for pain reduction and foot function improvement. Among all conservative options, CFO is routinely used in clinical practice and widely recommended.

Eligibility Criteria:
Inclusion Criteria:

* Reaching the specific criteria of PHP including (15)

  * A complaint of tenderness from the palpation of the medial calcaneal tubercle and the medial aspect of the proximal portion of the plantar fascia, or pain along the plantar fascia at medial longitudinal arch side
  * The presence of heel pain immediately during the first few steps of walking in the morning or after prolonged period of inactivity; and gradually decreased throughout the day with ordinary walking; and worsened with prolonged activity
* Having the symptom of heel pain for at least 6 weeks, indicating the chronic condition (29)
* Having maximum level of pain intensity during last week using visual analog scale (VAS) ranging from 3 to 6 mm

Exclusion Criteria:

* Having BMI more than 30 kg/m2 (40)
* Having leg length difference more than 1 cm (30)
* Unable to perform the exercise program
* Having positive sciatica test, indicating the L5-S1 nerve root irritation
* Having history of lower extremity fracture
* Having history of lower extremity surgery
* Having been diagnosed with gout, diabetic neuropathy, rheumatoid arthritis, systemic lupus erythematosus (SLE), cancer, infection disease and tumor