Exercise Therapy and Physical Activity Modification for Patients With Sever's Disease

Sever's disease (calcaneal apophysitis) is a debilitating overuse injury to the calcaneal apophysis (growth plate) caused by repetitive traction stress on the growth plate. The condition occurs in 3.7 per 1,000 young patients, most commonly between ages 8-15 years old. Patients with Sever's disease experience months of heel pain with running and jumping activities, reduced quality of life, and struggle to participate in social and sports activities. Symptoms can progress from self-limiting to complete loss of function and may persist into adulthood, leading to early retirement from sport. Therefore, effective rehabilitation is essential to curb the substantial negative implications on physiological and psychological health that may continue into adulthood and contribute to healthcare utilization and global physical inactivity trends.

There is a lack of high-quality evidence to guide intervention for Sever's disease. Expert opinion maintains that pain and dysfunction resolve spontaneously when patients reach skeletal maturity. As a result, palliative interventions consisting of activity avoidance or cessation are often prescribed for symptom relief. At the tissue level, these passive strategies risk the healthy maturation of load-bearing tissues through physical activity (PA) in the most critical years of growth.Recent evidence of altered Achilles tendon structure in patients with Sever's disease suggests this condition may have lifelong implications. This underscores an immediate need to develop an evidence-based treatment strategy that supports tissue remodeling during this critical time of growth and encourages a physically active lifestyle in adulthood. Exercise therapy promotes tissue healing and is effective for patients with Achilles tendinopathy and other apophyseal injuries. Our pilot study determined that this treatment approach is feasible and safe for patients with Sever's disease and preliminary results support conducting a larger clinical trial to determine efficacy to improve clinical outcomes. We propose to conduct a 12-week randomized controlled trial to evaluate the effectiveness of a comprehensive tendon-loading protocol compared to a palliative control approach for treating Sever's disease. The experimental group (EXP) will receive a comprehensive intervention including a tendon-loading protocol and education on daily pain monitoring to allow continued sports participation within a tolerable pain range. The control group (CTL) will be instructed to participate in activities of daily life and sports as tolerated. Both groups will be provided gel heel cups and an activity diary. Both groups will be asked to don a wearable ActivPAL activity monitor for seven consecutive days after data collection at baseline, 6-, and 12- weeks. Our specific aims are: (1) To determine if the comprehensive intervention produces clinically meaningful improvement in symptom severity, lower extremity function, and psychosocial factors compared to palliative care over 12 weeks. (2) Evaluate changes in triceps surae and Achilles tendon morphology and mechanical properties over time. (3) Explore weekly PA volume and intensity at time of diagnosis and changes during intervention.

The experimental group will receive supervised progressive tendon-loading exercise therapy, pain-guided activity modification education, and feedback on daily activity. Both groups will receive gel heel cushion inserts for footwear.

Behavioral: Exercise

The control group will not receive progressive tendon-loading exercise. The control group will receive the same education as the experimental group, except the control group will be asked to participate in activities as tolerated and rest as needed. The control group will be asked to record the same activity diary as the experimental group, but will not receive feedback on their daily activity. Both groups will receive gel heel cushion inserts for footwear.

Other: Active Control

Therapeutic Achilles-tendon loading exercise; Activity modification using a Pain Monitoring Model

Conventional Clinician advice for pediatric overuse injury management.

Time frame: Baseline, 6 weeks, and 12 weeks after randomization.

The Victorian Institute of Sport Assessment-Achilles (VISA-A) will be used. Survey completed via participant interview at baseline. Survey completed online by participants for follow-up visits.

Time frame: Baseline, 6 weeks, and 12 weeks after randomization.

Participants will be instructed to keep their arms behind their back and jump as high as possible on a flat surface. Jump height will be measured in cm via the MuscleLab contact grid.

Time frame: Baseline, 6 weeks, and 12 weeks after randomization.

The drop CMJ is performed by standing on the edge of a 20cm box, then stepping off to land and immediately rebounding as high as possible. Jump height will be measured in cm via the MuscleLab contact grid.

Time frame: Baseline, 6 weeks, and 12 weeks after randomization.

The heel-rise endurance test is performed barefoot while standing on a single leg on a slant board fixed at 10 degrees of dorsiflexion. Participants will be instructed to perform as many heel-rises as possible while maintaining a straight knee and a slight forward lean, lifting the heel as high as possible, to a metronome set at 60 beats/min (30 heel-rises/min). Participants will place only two fingers from each hand on the wall to maintain balance. The test will conclude when the participant is unable maintain the test cadence, elect to stop due to fatigue or pain, or perform consistent repetitions with compensation. A linear encoder will be taped to the posterior calcaneus, which records linear displacement (heel-rise height, cm) for each repetition. Total heel-rise work will be calculated in Joules by summing the displacement for each repetition, multiplied by body mass and the force of gravity.

Time frame: Baseline, 6 weeks, and 12 weeks after randomization.

B-mode ultrasound imaging (GE P9 Xdclear R4.5, GE Healthcare) will be used to assess the Achilles tendon cross-sectional area in short-axis images. CSA will be measured at the thickest portion of the free Achilles tendon.

Time frame: Baseline, 6 weeks, and 12 weeks after randomization.

Shear wave velocity (SWV) will be measured using Ultrasound Shear Wave Elastography. SWV is a measurement of resistance to deformation (stiffness) in tendon. Participants will be positioned prone, with legs past the mid-shank suspended over the edge of the exam table and feet resting against a custom wall-mounted slant board to fix the ankles at 15 degrees of dorsiflexion. The region of interest will be between the anterior-posterior borders of the Achilles tendon visualized on b-mode ultrasound imaging in longitudinal axis and centered over the thickest portion of the free Achilles tendon. This distance will be documented from the cephalad border of the Achilles tendon osteotendinous junction (calcaneal notch). In cases of uniform thickness, the ROI will be standardized to 2cm proximal to the calcaneal notch. The average of three trials will be analyzed.

Time frame: Baseline, 6 weeks, and 12 weeks after randomization.

The percentage of white to greyscale pixels (range 0-255) is calculated within a region of interest using the LAX Achilles tendon thickness images.

Time frame: 2 weeks before randomization, Baseline, 6 weeks, and 12 weeks after randomization.

Number of steps taken during waking hours measured using a wearable accelerometer- and inclinometer-based sensor (ActivPAL). Participants will wear the device continuously for 7 days at each study time point.

Time frame: 2 weeks before randomization, Baseline, 6 weeks, and 12 weeks after randomization.

Daily minutes/day spent sitting, standing, stepping, and being sedentary will be averaged for each participant across all valid days using a wearable accelerometer- and inclinometer-based sensor (ActivPAL4+). Participants will wear the device continuously for 7 days at each study time point. Additionally, daily minutes at a moderate-to-vigorous activity stepping cadence will be analyzed.

Time frame: Baseline, 6 weeks, and 12 weeks after randomization.

Assesses foot and ankle-related symptoms, function, participation, and quality of life

Time frame: Baseline, 6 weeks, and 12 weeks after randomization.

Not reported in this registry record.

Time frame: Baseline, 6 weeks, and 12 weeks after randomization.

Not reported in this registry record.

Time frame: 6 weeks, and 12 weeks after randomization.

"Please rate the overall change in your condition from the time that you began the study until now." Measured on an 11-point likert scale, where -5 is "A very great deal worse", 0 is "No change", and +5 is "A very great deal better".

Time frame: 6 weeks, and 12 weeks after randomization.

"On a scale of 0 - 100, please rate the use/function of your injured body part?" 0 is No Function/Unable to Use Injured Body Part, and 100 is ull Function/ Full use of Injured Body Part.

Time frame: 6 weeks, and 12 weeks after randomization.

"How satisfied are you with the current use/function of your injured body part?" 0-10 scale, where 0 is "Not satisfied" and 10 is "Very satisfied".

Time frame: 6 weeks, and 12 weeks after randomization.

"Considering all the activities and sports you do each day, how much you hurt, and what you can do with and without pain, are you satisfied with your current condition?" Yes/No answer.

Exercise Therapy and Physical Activity Modification for Patients With Sever's Disease: A Randomized Controlled Trial