Individualized Rehabilitation for Osgood-Schlatter or Sever Pain in Youth Athletes (LEAP-REHAB)

Feasibility, Clinical Response, and Exploratory Predictors of an Individualized Load-Based Rehabilitation Pathway in Youth Athletes With Osgood-Schlatter Disease or Sever Disease: A Prospective Single-Arm Interventional Study

The goal of this clinical trial is to learn if a 12-week individualized rehabilitation program is feasible and helpful for children and adolescents with lower-extremity apophyseal pain, including Osgood-Schlatter-related knee pain and Sever-related heel pain. It will also learn about how well participants follow the program, whether the program can be delivered as planned, and whether pain, function, and sports participation improve during rehabilitation.

The main questions it aims to answer are:

1. Can this rehabilitation program be delivered with good attendance, good home-exercise adherence, and complete follow-up data?
2. Do pain, function, and sports participation improve during the rehabilitation period?
3. Which baseline clinical, functional, ultrasound, maturity, or biomarker features may help explain who responds better to rehabilitation?

All participants will receive the same overall rehabilitation framework. The program includes education, pain and load monitoring, an activity-ladder approach, symptom-guided exercise progression, motor-control training, basic strength exercises, and gradual return to running, jumping, landing, and sport-specific activities. Exercises are individualized according to symptoms, current activity level, movement quality, treatment tolerance, and clinical judgement.

Participants will:

1. Attend baseline and follow-up physiotherapy assessments.
2. Receive an individualized rehabilitation plan with education, pain and load monitoring, and home exercises.
3. Complete home exercises and keep a short symptom and activity log.
4. Attend in-person physiotherapy review visits during the rehabilitation period.
5. Answer questionnaires about pain, function, perceived change, and sports participation during follow-up.

Study Overview

• Status: Not yet recruiting
• Conditions: Sever's Disease; Osgood-Schlatter Disease; Apophyseal Pain
• Intervention / Treatment: Behavioral: Individualized Load-Based Rehabilitation Pathway

Detailed Description

This study evaluates a 12-week individualized rehabilitation pathway for youth athletes with current or previous lower-extremity apophyseal pain, including Osgood-Schlatter-related knee pain and Sever-related heel pain. The study is designed as a prospective, single-arm interventional feasibility study with exploratory clinical-response and predictor analyses.

The rehabilitation pathway includes a standardized core framework delivered to all participants. The core components are education, pain and load monitoring, activity modification, symptom-guided progression, home-exercise prescription, basic strength exposure, motor-control training, and gradual return to sport-related loading. The main clinical emphasis is on improving load tolerance and movement quality during tasks relevant to youth sport, such as squatting, single-leg control, step or split-squat patterns, calf-loading tasks, landing, deceleration, running, and sport-specific activities.

The intervention is individualized pragmatically rather than by formal treatment allocation rules. Exercise selection and progression are adjusted according to each participant's symptoms, current participation level, irritability, movement quality, tolerance of the prescribed exercises, response after exercise, and clinical judgement. Baseline clinical and functional tests may include measures of range of motion, muscle strength, movement quality, ultrasound features, maturation, and biomarkers. These measures are used for participant characterization, safety monitoring, and exploratory predictor or moderator analyses. They are not used as a deterministic algorithm for assigning participants to separate treatment modules.

All participants receive the same overall rehabilitation pathway, but the exact exercise variants, starting level, loading dose, rate of progression, and temporary regressions may differ between participants. The rehabilitation program includes in-person physiotherapy visits at baseline and planned review time points, together with a home exercise program. Participants and families receive instructions on how to monitor pain, symptoms, and sport exposure, and how to respond if symptoms increase.

Progression is guided by symptom response and movement quality rather than by fixed timelines alone. Pain during exercise, symptom response after the session and the next day, perceived exertion, and visible movement quality are used to decide whether to maintain, progress, regress, or temporarily pause selected exercises or activity levels. Participants are instructed to report relevant symptom worsening, limping, swelling, new pain, or adverse events to the physiotherapy team.

The rehabilitation pathway uses an activity-ladder approach to guide return to participation. Sport participation and load exposure are monitored separately, because a participant may tolerate some parts of training while still being unable to tolerate higher-load tasks such as sprinting, jumping, landing, rapid deceleration, or match play. Return to sport is therefore progressed stepwise and individualized to symptom response.

The study also includes exploratory responder and predictor analyses. Baseline clinical features, symptom irritability, functional performance, ultrasound findings, maturity-related variables, and selected biomarkers may be examined as potential predictors or moderators of clinical response. These analyses are exploratory and are not intended to establish causal treatment effects between subgroups.

This rehabilitation study is methodologically linked to the separately registered pilot sham-controlled photobiomodulation trial in youth athletes with apophyseal pain (NCT07446517). Participants who complete that trial may enter this rehabilitation study through a post-trial pathway. Other eligible participants may enter the rehabilitation study directly after baseline assessment. The present study is registered separately because the rehabilitation intervention, timing of entry, and clinical questions differ from those of the photobiomodulation trial.

• Study Type: Interventional
• Enrollment (Estimated): 45
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Bartosz Wilczyński, PhD; Phone Number: +48 732 414 195; Email: bartosz.wilczynski@gumed.edu.pl

Study Locations

• Poland
  • Debinki 7
    • Gdansk, Debinki 7, Poland, 80-210
      • Department of Immunobiology and Environment Microbiology
      • Contact: Bartosz Wilczyński; Phone Number: +48 58 349 17 66; Email: immunobiol@gumed.edu.pl

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Aged 10 to 17 years
• Participates in organized sport and has at least 12 months of sport participation or training history
• Has current lower-extremity apophyseal pain consistent with Osgood-Schlatter-related knee pain and/or Sever-related heel pain, or has previous Osgood-Schlatter-related or Sever-related symptoms with a residual or low-irritability presentation relevant to rehabilitation
• Meets criteria for at least one pre-specified rehabilitation entry pathway:

post-trial rehabilitation entry after completion of the separate photobiomodulation trial, or direct-entry rehabilitation with active apophyseal symptoms, or direct-entry rehabilitation with previous Osgood-Schlatter-related or Sever-related symptoms and a low-irritability or residual presentation

For participants entering with active symptoms:

• pain is located at the tibial tubercle region and/or the calcaneal apophyseal/heel region
• pain is aggravated by activity, loading, or sport participation
• pain is reproducible on clinical examination or the clinical history is consistent with the target condition

Participant and parent/caregiver are willing to take part in the rehabilitation program, including in-person visits, home exercises, symptom/activity monitoring, and follow-up assessments.

A parent or legal guardian provides written informed consent, and the participant provides assent when applicable.

Exclusion Criteria:

• Current pain episode started after an acute traumatic injury that better explains the symptoms
• Clinical presentation suggests a condition other than the target rehabilitation condition, including a major alternative knee or heel diagnosis requiring different management
• Lower-limb surgery that would substantially affect rehabilitation planning, safety, or interpretation of outcomes
• Known serious musculoskeletal, neurological, rheumatological, inflammatory, autoimmune, metabolic, or other systemic disease that may affect safe participation or interpretation of outcomes
• Any medical or developmental condition that would prevent safe participation in exercise-based rehabilitation
• Current symptoms requiring urgent medical assessment or management outside the rehabilitation pathway
• Inability to understand study instructions or complete study procedures with parent/caregiver support
• Parent/caregiver or participant does not agree to participate or withdraws consent/assent

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: Individualized Load-Based Rehabilitation Pathway; Participants receive a 12-week individualized rehabilitation pathway for current or previous lower-extremity apophyseal pain, including Osgood-Schlatter-related knee pain and Sever-related heel pain. The intervention includes education, pain and load monitoring, activity modification, symptom-guided exercise progression, motor-control training, basic strength exercises, and gradual return to sport-related loading. All participants receive the same overall rehabilitation framework, but the starting level, exercise variants, dose, progression, and temporary regressions are adjusted according to symptoms, current activity level, movement quality, treatment tolerance, response after exercise, and clinical judgement. Participants may enter after completion of a separate photobiomodulation trial, by direct entry with active symptoms, or by direct entry with previous symptoms and a low-irritability or residual presentation. These entry routes are not treatment arms.

Behavioral: Individualized Load-Based Rehabilitation Pathway; This intervention is a 12-week individualized rehabilitation program for youth athletes with current or previous lower-extremity apophyseal pain, including Osgood-Schlatter-related knee pain and Sever-related heel pain. The program includes education, pain and load monitoring, activity modification, symptom-guided exercise progression, motor-control training, basic strength exercises, and gradual return to sport-related loading. All participants receive the same overall rehabilitation framework. The starting level, exercise variants, dose, progression, and temporary regressions are adjusted according to symptoms, current activity level, movement quality, treatment tolerance, response after exercise, and clinical judgement. Progression is guided by pain during exercise, symptom response after the session and the next day, perceived exertion, and movement quality, rather than by fixed timelines alone.; Other Names: Activity-Ladder Rehabilitation; Symptom-Guided Rehabilitation Program; Load-Tolerance Rehabilitation Program

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Home Exercise Adherence During the Rehabilitation Period	Proportion of participants achieving the pre-specified home-exercise adherence target, defined as completing home exercises during at least 70% of study weeks.	From rehabilitation entry through completion of the rehabilitation period (approximately 12 weeks)
Retention: Proportion of Participants Completing Follow-Up Assessment	Proportion of enrolled participants who complete the planned follow-up assessment at the end of the rehabilitation period.	From rehabilitation entry to end-of-study follow-up (approximately 12 weeks)
Safety: Number and Type of Adverse Events During Rehabilitation	Count and classification of adverse events temporally associated with the rehabilitation program, including symptom flare requiring modification, new musculoskeletal injury, or other clinically relevant problems during study participation.	From rehabilitation entry through completion of the rehabilitation period (approximately 12 weeks)
Feasibility of Rehabilitation Delivery: Proportion of Participants Completing the Planned In-Person Rehabilitation Review Visits	Proportion of participants who complete the planned in-person physiotherapy review visits during the 12-week rehabilitation period. Successful completion will be defined as attendance at the minimum planned core visit set, including baseline rehabilitation entry and at least the planned follow-up review visits required by the protocol.	From rehabilitation entry through completion of the rehabilitation period (approximately 12 weeks)
Intervention Fidelity: Proportion of Rehabilitation Visits Delivered According to Protocol	Proportion of in-person rehabilitation visits in which the required protocol elements were delivered and documented. Required elements include pain and load monitoring, review of symptoms and activity exposure, exercise review, progression or regression decision, and home-program update.	From rehabilitation entry through completion of the rehabilitation period (approximately 12 weeks)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change From Baseline in Worst Pain During the Last 7 Days as Measured by the Numeric Pain Rating Scale (NPRS)	NPRS ranges from 0 to 10, where 0 = no pain and 10 = worst pain imaginable. The main metric will be change in worst pain in the last 7 days from baseline to follow-up.	Baseline and approximately 12 weeks
Change From Baseline in Knee Function as Measured by the Knee Injury and Osteoarthritis Outcome Score for Children (KOOS-Child) in the Osgood-Schlatter Subgroup	The Knee Injury and Osteoarthritis Outcome Score for Children (KOOS-Child) is a child-reported knee-specific questionnaire. Subscale scores are transformed to a 0 to 100 scale, where higher scores indicate better knee status, fewer symptoms, and better function. The primary metric will be change from baseline to approximately 12 weeks in the overall KOOS-Child score in the Osgood-Schlatter subgroup.	Baseline and approximately 12 weeks
Change From Baseline in Foot/Ankle Function as Measured by the Oxford Ankle Foot Questionnaire for Children (OxAFQ-C) in the Sever Subgroup	The Oxford Ankle Foot Questionnaire for Children (OxAFQ-C) is a child-reported measure of foot and ankle function. Domain scores are transformed to a 0 to 100 scale, where higher scores indicate better foot and ankle function and lower symptom impact. The metric is change from baseline to approximately 12 weeks in the overall OxAFQ-C score in the Sever subgroup only.	Baseline and approximately 12 weeks
Return-to-Sport Status at Follow-Up	Return-to-sport status will be classified using pre-specified participation categories describing the participant's current level of sport involvement, ranging from restricted participation to full return to sport without planned limitations. Status will be recorded as an ordinal category at follow-up to describe sport participation during and after rehabilitation.	Approximately 12 weeks
Proportion of Participants Reporting Meaningful Improvement on the Patient Global Impression of Change (PGIC) at Approximately 12 Weeks	PGIC is a 7-point scale of overall perceived change, ranging from very much improved to very much worse. Meaningful improvement is defined a priori as a rating of "much improved" or "very much improved." This outcome will be reported as the proportion of participants meeting that threshold at approximately 12 weeks.	Approximately 12 weeks
Proportion of Participants Requiring Rehabilitation Regression or Temporary Exercise Modification During the Rehabilitation Period	This outcome will be reported as the proportion of participants who require at least one clinically indicated regression or temporary modification of the rehabilitation program during the 12-week period. Regression or modification may include reducing exercise dose, reducing range of motion, reducing external load, simplifying the exercise variant, temporarily pausing a selected exercise, or modifying sport-related activity because of symptom worsening, reduced movement quality, adverse next-day response, or other clinical concerns.	From rehabilitation entry through completion of the rehabilitation period (approximately 12 weeks)

Collaborators and Investigators

• Sponsor: Medical University of Gdansk
• Investigators: Principal Investigator: Bartosz Wilczyński, Medical University of Gdansk

Study record dates

Study Major Dates

• Study Start (Estimated): May 20, 2026
• Primary Completion (Estimated): April 5, 2027
• Study Completion (Estimated): April 5, 2029

Study Registration Dates

• First Submitted: March 31, 2026
• First Submitted That Met QC Criteria: April 7, 2026
• First Posted (Actual): April 9, 2026

Study Record Updates

• Last Update Posted (Actual): May 20, 2026
• Last Update Submitted That Met QC Criteria: May 16, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Rehabilitation; Knee Pain; Physical Therapy; Exercise Therapy; Return to Sport; Heel Pain; Youth Athletes; Osgood-Schlatter Disease; Sever's Disease; Load Management; Apophyseal Pain
• Additional Relevant MeSH Terms: Bone Diseases; Musculoskeletal Diseases; Osteochondrosis
• Other Study ID Numbers: KB/591/2025-2026-REHAB; 71-01428 (Other Identifier: Young Creator of Science" grant program, Excellence Initiative - Research University, Medical University of Gdańsk)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: De-identified individual participant data (IPD) that underlie the results reported in publications from this study will be made available to qualified researchers. Shared data may include baseline characteristics, rehabilitation entry pathway, intervention exposure variables, adherence and fidelity measures, clinical outcomes, and adverse events, together with a data dictionary. Data will be shared after publication of the primary results and will remain available for at least 5 years.
• IPD Sharing Time Frame: The study protocol will be made openly available through the Open Science Framework (OSF). De-identified individual participant data, the statistical analysis plan, and analytic code will be made available after publication of the primary study results and will remain available for at least 5 years after publication.
• IPD Sharing Access Criteria: The study protocol will be openly accessible through OSF. De-identified individual participant data, the statistical analysis plan, and analytic code will be available to qualified researchers upon reasonable request and approval of a methodologically sound proposal. Data will be shared only for non-commercial research purposes and after signing a data use agreement.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ANALYTIC_CODE

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No