Plantar Heel Pain: Multisegment Foot Motion and Muscle Function, FFI Translation, and Evaluation of Treatments (Subproject1) Effectiveness of Strengthening Exercise Program on Symptoms in Patients With PHP (Subproject3)

(Subproject 1) "Plantar heel pain (PHP)" or "plantar fasciitis" is one of the major foot problems which can occur in any age group. It is a commonly encountered musculoskeletal problem that can cause disability, activity limitation, discomfort, and affect the quality of life. It involves pain and inflammation of the plantar fascia, which runs across the bottom of the foot and connects the heel bone to toes. PHP frequently found in active workers aged between 25 and 65 years with the highest incidence in people aged between 40 and 60 years.

However, very few studies investigated the alterations of the multisegmental foot motions and muscle functions in patients with PHP. To prescribe the relevant program of treatment and reduce the risk of symptoms chronicity, it is necessary to have an in-depth understanding of changing mechanisms in patients with PHP. To explain how the symptoms occur in patients with PHP, foot function is another aspect that should be determined. One of the popular questionnaires determining foot function is the Foot Function Index (FFI) questionnaire. It has been proved to have good reliability and validity and has been translated into several languages. To be able to use the international standard questionnaire, it is necessary to translate the FFI into Thai. This can be implemented in Thailand and be able to compare the findings of the interventional effect internationally. In addition, very few studies reported the effectiveness of the treatment program for patients with PHP. Among previous evidences, the controversial findings existed. Thus, the intervention program should be evaluated for obtaining the effective treatment for this population.

(Subproject 3) The objectives of the study will be General Objective is to investigate the effectiveness of strengthening exercise program on symptoms in patients with plantar heel pain.

Specific Objectives is to compare the effectiveness between physical therapy treatment program with strengthening exercise and with stretching exercise on foot function score, pain at worst score, plantar fascia thickness, muscles strength, ankle motion, and gait parameters in patients with plantar heel pain among baseline, after 4th and 8th of treatments, and after 1st and 2nd month of self-home based exercise.

(Sub-project 1) Procedure

Each participant will attend data collection on a single occasion and allocate into the healthy or patients with PHP with the selection criteria before enrollment. They will dress with short pants which researcher prepare. Before testing, the NORAXON TeleMyo Receiver will be synchronized with the forceplate and video. The real-time signal of motion, EMG, and force data will simultaneously synchronize and present on the screen.

EMG preparation

The skin will be prepared over the sites for electrode placements by shaving, lightly abrading, and cleaning with 70% alcohol prior to electrode application. The electrodes will place 20 mm center to center interelectrode space over the site in each muscle. Interelectrode impedance is less than 10 kiloohm. The elastic adhesive tape is used to fixed electrodes to control movement artefacts. Participants will perform reference contractions to check the placement and cross-talk of the electrodes between EMG signals from different muscles prior to data collection.

EMG placement

Muscle activation will be measured by electromyography (TeleMyo DTS Telemetry, NORAXON USA Inc.) at a sampling frequency of 1000 Hz in order to quantify the dynamic muscle function of the lower extremity. Surface electrodes will be placed according to recommendations of the European Recommendations for Surface Electromyography (SENIAM). Pairs of wet-gelled bipolar Ag-AgCl Dual surface electrodes (Ag/AgCl NORAXON Dual electrodes 20 mm spacing) are selected for surface EMG sensor. The location and orientation of electrode placements are localized in the supine position by the same researcher. The electrode will be placed on Peroneus longus (PL) which will be placed at 1/4 on the line between the tip of the fibular and tip of the lateral malleolus. Tibialis anterior (TA) electrode will be placed at 1/3 on the line between the tip of the fibular and tip of the medial malleolus. Gastrocnemius medial head (GM) and Gastrocnemius lateralis (GL) electrodes will be placed on the largest bulb of the muscle at medial head. All exact position of the muscles will confirm by their actions.

Maximum Voluntary isometric contraction (MVIC) test

Participants perform 5 seconds MVIC against manual resistance in each of the muscle for 3 times. The PL and TA will be assessed in supine lying position and gastrocnemius will be assessed in standing position. Participants will perform the action of each muscle against manual resistance from researcher and equipment. The peak amplitude of EMG signal in each trial will be selected and will be averaged from 3 seconds over the EMG. The peak mean amplitude of the 3 trials for each muscle will be used for normalization.

Anthropometric data assessment

Anthropometric data will be obtained from each subject for calculating the kinematic and kinetic data. It includes body height, body weight, leg length, and joint widths of the knee and ankle. Leg length is the distance between anterior superior iliac spine (ASIS) and medial malleolus. The knee width is the distance between medial and lateral condyles across the knee joint. The ankle width is the distance between medial and lateral malleoli.

Marker placement

The lower body markers of Plug-in-Gait will be used in the study to observe lower extremity motion data during walking. The model consists of left and right anterior superior iliac crests, left and right posterior superior iliac crests, left and right knees, left and right thighs, left and right ankles, left and right tibias, left and right toes, left and right heels. Right back marker will be used for the markers auto-label process in order to discriminate the left or the right.

Foot model

The markers will be placed on foot bony prominence following the Oxford Foot Model to obtain multisegmental foot motion during walking. The Oxford Foot Model has been used in previous studies to determine the multisegmental foot motion (35, 36) and proved to be validated and reliable (35, 36).

To define the forefoot segment, markers will be placed on the most distal, medial aspect of the first metatarsal shaft, the most proximal and distal lateral aspects of the fifth metatarsal shaft, and midway between second and third metatarsal heads. For the rearfoot segment, markers will be placed on sustentaculum tali, lateral calcaneus, heel (distal part of the calcaneus), posterior proximal calcaneus and a peg marker will be placed on posterior calcaneus between the heel and proximal calcaneus markers. For the tibial segment, markers will be placed on medial malleolus, lateral malleolus, anterior aspect of tibial crest, tibial tuberosity and head of fibula.

Prior to comparing the foot and ankle kinematic data between patients with PHP and normal healthy, repeatability of data will be assessed by intraclass correlation coefficient (ICC) values among trials of walking for ensuring the data can be acceptable, especially in the pathologic condition of the foot as PHP.

Gait measurement

Participants will walk on the 8-meters walkway until they familiar with the environment of the laboratory. Then, gait data will be collected for 3 success trials at their comfortable speed. Motion data will be collected at 100 Hz and will be filtered by using the Butterworth filtering technique at 5 Hz. Averaged data of EMG and motion from 3 trials will be used for further analysis.

(Sub-project 3)

This study will recruit patients with Plantar heel pain (PHP) from the Physical Therapy Center, Faculty of Physical Therapy, Mahidol University. The eligible participants will be screened and recruited following the inclusion and exclusion criteria. The participants will be screened according to the criteria. Purposes, procedures, and possible risks of the study will be explained to the participants. Prior to participating in the study, they will sign in the informed consent. The participants will be allocated into the group of intervention, which is the experimental (strengthening) group and the control (stretching) group, according to the stratified randomization technique. The participants will be assessed all outcomes for the baseline; pain at worst, FFI, plantar fascia thickness, muscle strength, ankle range of motion and gait measurement.

After that, all participants will be received the same conservative treatment (therapeutic ultrasound, tissue mobilization, and joint mobilization) by the experienced physician. Then, the participants will be instructed to do the exercise following the program of their allocated group. The experimental group will be performed toe flexor muscle exercise, ankle evertor muscles exercise, and high-loading strength training, but the control group will be performed the gastrocnemius muscle, soleus muscle and plantar fascia stretching. All participants will be treated for 8 times (2 times per week) and perform the home-based exercise program three times a day. After the treatment end, the participants will continue their home-based exercise for 2 months. The home-based exercise protocol will be prescribed by the physical therapist.

The assessment of all outcomes data will perform for 5 times; 1) baseline, 2) after 4th and 3) 8th of treatments, and 4) after 1st and 5) 2nd month of self-home based exercise. The researcher who evaluates the outcome data will be blinded to the group of participant. They will be involved only in the admission, randomization, physical examination, and discharge. All physical therapists will be undergoing the meeting and practical session to clarify the study protocol and treatment guidelines. To ensure the participants able to do home program exercise properly, the understanding and compliance will be checked by phone call and record the number of exercise in the logbook.

The statistical significance will be estimated at probability (p-value \< 0.05). The descriptive statistic will be used to analyze the demographic and baseline characteristics of the participants. The Kolmogorov- Smirnov Goodness of Fit test will be tested the data distribution. The baseline data will be compared between groups to investigate the difference by using the independent t-test and Mann-Whitney U test for normal and non-normal distribution of data. The outcome measurements are the VAS score, FFI score, gait parameter, plantar fascia thickness, muscle strength, and ankle ROM will be analyzed by the two-way repeated ANOVA among baseline, after 4th and 8th of treatments, and after 1st and 2nd month of self-home based exercise. If the data are not normally distributed, Friedman test will be used to compare the mean differences.

Eligibility Criteria:
(Sub-project 1) Inclusion criteria

Patients with PHP:

* Age between 20 - 80 years
* History of PHP for at least 1 month before enrollment
* Pain or tenderness on palpation of the medial calcaneal tubercle or the proximal plantar fascia
* Occurring at least one of the following complaints: pain on the first step in morning or after prolonged sitting, pain on prolonged standing, or pain when running
* Thickness of the plantar fascia of 4.0 mm or greater assessing by US diagnosis

Healthy:

* No past or present history of PHP or foot pain Exclusion criteria
* Any coexisting painful musculoskeletal conditions of lower extremity; achilles or tibialis posterior tendinopathy, acute ankle sprain, tarsal tunnel syndrome, heel pad syndrome
* Any fracture or surgery history in lower extremity and foot within 6 months
* Lumbar radiculopathy or central or peripheral neuropathy
* Systemic arthritis such as rheumatoid arthritis
* Neurological or vascular compromise of the foot related to diabetes
* Have a history of steroid injection within 6 months
* Leg length discrepancy more than 1 centimeter
* Currently taking pain medication

(Sub-project 3)

Inclusion criteria:

* Age between 20 - 80 years
* History of PHP for at least 1 month before enrollment
* Pain or tenderness on palpation of the medial calcaneal tubercle or the proximal plantar fascia
* Occurring at least one of the following complaints: pain on the first step in morning or after prolonged sitting, pain on prolonged standing, or pain when running
* Thickness of the plantar fascia of 4.0 mm or greater assessing by US diagnosis

Exclusion criteria:

* Any coexisting painful musculoskeletal conditions of lower extremity; achilles or tibialis posterior tendinopathy, acute ankle sprain, tarsal tunnel syndrome, heel pad syndrome
* Any fracture or surgery history in lower extremity and foot within 6 months
* Lumbar radiculopathy or central or peripheral neuropathy
* Systemic arthritis such as rheumatoid arthritis
* Neurological or vascular compromise of the foot related to diabetes
* Have a history of steroid injection within 6 months
* Leg length discrepancy more than 1 centimeter
* Pregnancy
* Administer other intervention programs or taking pain medication
* Unable to perform the treatment exercise program