The Effect of Additional Neurodynamic Intervention in Patients With Chronic Ankle Instability

Approximately 40% of acute ankle sprain would develop into chronic ankle instability (CAI). Chronic ankle instability is characterized by pain, repeated sprains and giving way. Recently, the pathomechanical impairment, sensory-perceptual impairment and motor-behavioral impairment have been documented in the chronic ankle instability model. Previous research revealed that compared to the control subjects, people with CAI had lower pressure pain threshold (PPT). This increased mechanosensitivity of the neural tissues around the ankle might account for pain and dysfunction in people with CAI. Also, the other study indicated that in subjects following ankle inversion sprain there is greater restriction of knee extension on the injured side compared to non-injured side in the slump test with the ankle plantar flexion and inversion, which may suggest the restriction in mobility of the common peroneal tract. However, the effects of neurodynamic intervention, which addresses the mechanosensitivity problems, in people with CAI are still unclear. Therefore, the aim of the study is to investigate the effect of additional neurodynamic intervention on the ankle range of motion, mechanosensitivity, balance performance and self-reported function.

Approximately 40% of acute ankle sprain would develop into chronic ankle instability (CAI). Chronic ankle instability is characterized by pain, repeated sprains and giving way. Recently, the pathomechanical impairment, sensory-perceptual impairment and motor-behavioral impairment have been documented in the chronic ankle instability model. Previous research revealed that compared to the control subjects, people with CAI had lower pressure pain threshold (PPT). This increased mechanosensitivity of the neural tissues around the ankle might account for pain and dysfunction in people with CAI. Also, the other study indicated that in subjects following ankle inversion sprain there is greater restriction of knee extension on the injured side compared to non-injured side in the slump test with the ankle plantar flexion and inversion, which may suggest the restriction in mobility of the common peroneal tract. However, the effects of neurodynamic intervention, which addresses the mechanosensitivity problems, in people with CAI are still unclear. Therefore, the aim of the study is to investigate the effect of additional neurodynamic intervention on the ankle range of motion, mechanosensitivity, balance performance and self-reported function. The investigators will recruit 40 patients with chronic ankle instability and compare the effect of two intervention groups (balance training alone, combined balance training and neurodynamic intervention for the common peroneal nerve) on ankle range of motion (ROM), active knee ROM, pressure pain threshold , Y balance test and Foot and ankle ability measure (FAAM). Independent test and Chi-square test are used to examine demographic data of the groups differences. Two-way repeated measures ANOVA is used to examine the intervention effect with the alpha level set at 0.05

The subjects will receive the balance training and neurodynamic intervention for the common peroneal nerve twice a week for 6 weeks.

The subjects will warm up to stretch the lower extremity for 5 minutes. The physical therapist will instruct the patient how to use the foot tripod within 5 minutes. And then, giving him or her balance training. At the first, the patient double legs stand on the ground to throw and catch a ball for 30 seconds, and then one leg stand on the ground to throw and catch a ball for 30 seconds. When finished, the patient can take 1 minutes rest. Second, the patient will finish the prescribed the task stand on different materials, which included the exercise mat, dynair, bosu and foam roller.

The physical therapist will give the patient neurodynamic intervention for the common peroneal nerve, which is performed slider the nerve 2 seconds. The slider technique is repeated 30 seconds for 4 times, each time can be take a rest 1 minutes. The physical therapist will instruct the patient how to use the foot tripod within 5 minutes. And then, giving him or her balance training. At the first, the patient double legs stand on the ground to throw and catch a ball for 30 seconds, and then one leg stand on the ground to throw and catch a ball for 30 seconds. When finished, the patient can take 1 minutes rest. Second, the patient will finish the prescribed the task stand on different materials, which included the exercise mat, dynair, bosu and foam roller.

Ask the person to face the wall and the tested foot in front, then the second toe and heel in the line is perpendicular to the wall. The contralateral limb is positioned behind the testing limb in a comfortable position and hands are placed on the wall in front to maintain stability. The gravity inclinometer is placed at the tibial tuberosity to measure the angle. The subjects will lunge forward trying to touch a vertical line on the wall with their knee, at the same time keeping heel contact with ground. Participants will perform three practice trials followed by 3 test trials and average the 3 tests.

Ask the person to face the wall and the tested foot in front, then the second toe and heel in the line is perpendicular to the wall. The contralateral limb is positioned behind the testing limb in a comfortable position and hands are placed on the wall in front to maintain stability. The gravity inclinometer is placed at the tibial tuberosity to measure the angle. The subjects will lunge forward trying to touch a vertical line on the wall with their knee, at the same time keeping heel contact with ground. Participants will perform three practice trials followed by 3 test trials and average the 3 tests.

Using the plastic universal goniometer to measure the pain pressure threshold (PPT) of the anterior talofibular ligament, calcaneofibular ligament, peroneal nerve, peroneal longus muscle and peroneal brevis muscle. Measure a total of three times, and take a 30 seconds rest interval each time. In the end, the investigators will take average of the 3 tests.

Using the plastic universal goniometer to measure the pain pressure threshold (PPT) of the anterior talofibular ligament, calcaneofibular ligament, peroneal nerve, peroneal longus muscle and peroneal brevis muscle. Measure a total of three times, and take a 30 seconds rest interval each time. In the end, the investigators will take average of the 3 tests.

Mechanosensitivity: Slump test with ankle plantar flexion and inversion to measure active knee range of motion

The subjects sit on the edge of the bed without touching ground with their feet. The physical therapist assists the subjects to maintain the neutral pelvis position. First, ask the subjects flex the neck, trunk, and finally flex the lumbar to tighten the back. Second, while the subjects plantar and invert the ankle, participants will do the knee extension movement and record the angle of knee motion. Participants will perform three practice trials followed by 3 test trials and average the 3 tests.

Mechanosensitivity: Slump test with ankle plantar flexion and inversion to measure active knee range of motion

The subjects sit on the edge of the bed without touching ground with their feet. The physical therapist assists the subjects to maintain the neutral pelvis position. First, ask the subjects flex the neck, trunk, and finally flex the lumbar to tighten the back. Second, while the subjects plantar and invert the ankle, participants will do the knee extension movement and record the angle of knee motion. Participants will perform three practice trials followed by 3 test trials and average the 3 tests.

The subjects will stand on Y-balance kit and reach their legs alternatively to anterior, posterolateral and posteromedial direction with dominant leg first, in sequence. The subjects will practice 6 times first to familiarize the test procedure, then the final three measurements were collected and normalized with subject's lower limb length for statistical analysis.

The subjects will stand on Y-balance kit and reach their legs alternatively to anterior, posterolateral and posteromedial direction with dominant leg first, in sequence. The subjects will practice 6 times first to familiarize the test procedure, then the final three measurements were collected and normalized with subject's lower limb length for statistical analysis.

The Foot and Ankle Ability Measures (FAAM) is a self-report measure that evaluate physical function of lower extremities musculoskeletal disorders. The measurement includes two parts, activities of daily living subscale of 21 items and sports subscale of 8 items. For each question, the subjects will chose the appropriate answer that most clearly describes their condition within the past week. It is based on the 4-0 scale. (4: no difficulty, 3: slight difficulty, 2: moderate difficulty, 1: extreme difficulty, 0: unable to do) If an activity in question is limited by something other than their foot or ankle, the patient is asked to record N/A. The sum of the scores in the two parts is less than ninety points, indicating that there is ankle instability

The Foot and Ankle Ability Measures (FAAM) is a self-report measure that evaluate physical function of lower extremities musculoskeletal disorders. The measurement includes two parts, activities of daily living subscale of 21 items and sports subscale of 8 items. For each question, the subjects will chose the appropriate answer that most clearly describes their condition within the past week. It is based on the 4-0 scale. (4: no difficulty, 3: slight difficulty, 2: moderate difficulty, 1: extreme difficulty, 0: unable to do) If an activity in question is limited by something other than their foot or ankle, the patient is asked to record N/A. The sum of the scores in the two parts is less than ninety points, indicating that there is ankle instability

Inclusion Criteria: History of at least two ankle sprains in the same leg, of which the first sprain is more than one year Leading to at least one interrupted day of desired physical activity The Cumberland Ankle Instability Tool (CAIT) ≦ 24 Slump test in ankle plantar flexion with inversion: positive Exclusion Criteria: Pregnancy Surgical treatments Previous fractures in either lower extremity Any concomitant lower extremity pathology, for example, vascular disease, osteoarthritis and rheumatoid arthritis Significant pain or injury to the lumbar or cervical spine Regular use of medication: anti-inflammatory drugs, painkiller, steroid or muscle relaxants Previous manual therapy or exercise interventions received on the lower extremity within the previous 3 months