Low-Level Laser Therapy for Osgood-Schlatter or Sever Pain in Youth Athletes

Effect of Low-Level Laser Photobiomodulation on Pain, Function, Ultrasound Findings, and Biochemical Markers in Youth Athletes With Osgood-Schlatter Disease or Sever Disease: A Randomized, Double-Blind, Sham-Controlled Trial

The goal of this clinical trial is to learn if low-level laser therapy (also called photobiomodulation) works to treat knee or heel pain in physically active children and adolescents with Osgood-Schlatter disease or Sever disease. It will also learn about the safety of this treatment. The main questions it aims to answer are:

1. Does low-level laser therapy lower pain more than a sham (placebo) laser treatment?
2. Does low-level laser therapy improve daily and sport-related function more than a sham laser treatment?
3. What medical problems, if any, do participants have during the study?

Researchers will compare active low-level laser therapy to a sham (placebo) laser treatment. The sham treatment looks and feels the same but does not deliver therapeutic light. This comparison will show whether the laser therapy works better than placebo.

Participants will:

• Complete screening and a baseline visit
• Be randomly assigned to active laser therapy or sham laser therapy
• Receive a series of treatment sessions over [2 weeks]
• Answer short questionnaires about pain and function at baseline and follow-up visits
• Have ultrasound imaging and/or provide blood or urine samples for research measurements

Both participants and the study team who assess outcomes will not know which treatment group each participant is in until the study ends.

Study Overview

• Status: Recruiting
• Conditions: Sever's Disease; Osgood-Schlatter Disease
• Intervention / Treatment: Device: Photobiomodulation (Low-Level Laser Therapy); Device: Sham Photobiomodulation (Sham Laser Treatment)

Detailed Description

This pilot randomized, placebo-controlled, double-masked clinical trial evaluates the feasibility and preliminary clinical signal of laser photobiomodulation (low-level laser therapy; LLLT) in youth athletes (10-17 years) with symptomatic lower-extremity apophyseal pathology, primarily consistent with Osgood-Schlatter disease and/or calcaneal apophysitis (Sever disease) confirmed clinically and by ultrasound.

Participants will be randomized 1:1 to active LLLT or sham LLLT. The intervention consists of 10 sessions over 2 weeks (5 sessions/week) delivered with a class 3B GaAlAs (Gallium-Aluminum-Arsenide) laser device using standardized parameters (near-infrared wavelength range; continuous mode; preset energy density; contact application over the symptomatic apophyseal region). Sham procedures are identical in appearance, session duration, and device operation but deliver 0 mW output.

The primary objective is feasibility (recruitment, retention, adherence, data completeness, safety). Secondary objectives are estimate-only between-group differences in pain and function at post-intervention and follow-up. Mechanistic measures (biomarkers and ultrasound features) are exploratory and used to inform the design of a future full-scale trial.

• Study Type: Interventional
• Enrollment (Estimated): 30
• 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
  • Pomeranian
    • Gdansk, Pomeranian, Poland, 80-210
      • Recruiting
      • Department of Immunobiology and Environment Microbiology, Debinki 7
      • Contact: Bartosz Wilczyński, PhD; Phone Number: +48 58 349 17 66; Email: bartosz.wilczynski@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 with at least 12 months of training history
• Has knee pain at the tibial tubercle (Osgood-Schlatter-type pain) and/or heel pain at the back of the heel (Sever-type pain)
• Pain is worse with activity and reproduced by pressing on the painful area
• Pain intensity is 3 out of 10 or higher on the Numeric Pain Rating Scale (NPRS) during the clinical visit and in the last week (0 = no pain, 10 = worst pain imaginable)
• Symptoms have been present for at least 2 weeks
• For heel pain consistent with Sever disease, the heel squeeze test is positive
• Ultrasound shows findings consistent with an apophyseal injury at the painful site
• Has no signs of acute illness or infection on the assessment day and during the previous 14 days (for example, fever or "flu-like" symptoms)
• A parent/guardian provides written informed consent
• The participant provides assent (agreement) to take part

Exclusion Criteria:

• Current pain episode started after an acute injury (for example, fall, collision, ankle sprain, or similar trauma)
• Prior surgery on the lower limb
• Known diagnosis of patellofemoral pain syndrome (pain around/behind the kneecap)
• Known patellar instability (recurrent kneecap dislocations or giving way)
• Known complex regional pain syndrome
• History of lower-limb fracture
• Ultrasound shows clinically important abnormalities in the assessed area that are not consistent with the target condition (for example, calcifications or other significant findings)
• Known chronic or systemic disease that may affect the musculoskeletal system (for example, inflammatory joint disease or other clinically significant chronic conditions)
• Received any of the following in the last 3 months: steroid injection, hydrodilatation, or laser therapy
• Used non-steroidal anti-inflammatory drugs (NSAIDs) (for example, ibuprofen, naproxen) within the last 14 days, or currently uses them
• Clinically important abnormal blood test results (complete blood count) that may affect safety or data validity
• Parent/guardian or participant does not agree to participate, or withdraws consent/assent

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Triple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Active Photobiomodulation (Low-Level Laser Therapy); Participants will receive active photobiomodulation (low-level laser therapy) applied to the symptomatic apophyseal region (tibial tubercle for Osgood-Schlatter-type pain and/or calcaneal region for Sever-type pain) using standardized device settings and application procedures. Treatment will be delivered in a series of sessions over the intervention period. All participants will also receive the same standardized conservative-care guidance (e.g., education and exercise/activity advice) provided to both study arms.	Device: Photobiomodulation (Low-Level Laser Therapy); Active photobiomodulation (low-level laser therapy) delivered using a laser device applied to the symptomatic apophyseal region (tibial tubercle for Osgood-Schlatter-type pain and/or calcaneal region for Sever-type pain). Sessions will be provided according to a standardized schedule and preset device parameters (wavelength/output/dose and application time) specified in the protocol.; Other Names: Low-Level Laser Therapy; Laser Photobiomodulation
Sham Comparator: Sham Comparator; Participants will receive sham (placebo) laser treatment using the same device appearance, positioning, contact, and session schedule as the active intervention, but without delivery of therapeutic light. The sham procedure is designed to maintain blinding. All participants will also receive the same standardized conservative-care guidance (e.g., education and exercise/activity advice) provided to both study arms.	Device: Sham Photobiomodulation (Sham Laser Treatment); Sham (placebo) photobiomodulation delivered with an identical device appearance and treatment routine (positioning, contact, and session duration) but without delivery of therapeutic light. The sham procedure is intended to maintain participant blinding and matches the active intervention schedule.; Other Names: Placebo Laser Treatment; Inactive Laser Treatment

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Recruitment feasibility: proportion of eligible participants enrolled	Proportion enrolled among eligible candidates; threshold ≥80% within the recruitment window.	From first screening contact through completion of enrollment.
Retention feasibility: proportion completing post-intervention and follow-up assessments	Proportion with complete assessments at baseline and post-intervention; threshold ≤20% attrition.	Baseline to post-intervention (≈2 weeks) and baseline to follow-up (≈3 months).
Adherence feasibility: proportion of intervention sessions completed	Percentage of planned sessions completed (10 total); threshold ≥8/10 sessions and ≥80% adherence.	During the 2-week intervention period.
Data completeness feasibility: proportion of complete datasets for key clinical outcomes	Proportion of participants with complete NPRS/PGIC/PODCI; threshold ≥90% complete.	Baseline to follow-up (≈3 months).
Safety and tolerability: number and type of adverse events related to the intervention	Count and classification of adverse events temporally associated with treatment sessions.	During the 2-week intervention period.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Proportion of Participants Rated as Responders on the Patient Global Impression of Change (PGIC) at 2 Weeks	PGIC is a 7-point global change scale from "very much improved" to "very much worse." A responder is defined as "much improved" or "very much improved".	2 weeks
Proportion of Participants Rated as Responders on the Patient Global Impression of Change (PGIC) at 3 Months	PGIC is a 7-point global change scale from "very much improved" to "very much worse." A responder is defined as "much improved" or "very much improved."	3 months
Change From Baseline in Pain Intensity as Measured by the Numeric Pain Rating Scale (NPRS) at 2 Weeks	NPRS ranges from 0 to 10, where 0 = no pain and 10 = worst pain imaginable. Pain intensity refers to worst pain in the last 7 days. The metric is change from baseline to 2 weeks.	Baseline and 2 weeks
Change From Baseline in Pain Intensity as Measured by the Numeric Pain Rating Scale (NPRS) at 3 Months	NPRS ranges from 0 to 10, where 0 = no pain and 10 = worst pain imaginable. Pain intensity refers to worst pain in the last 7 days. The metric is change from baseline to 3 months.	Baseline and 3 months
Change From Baseline in Pediatric Function as Measured by the Pediatric Outcomes Data Collection Instrument (PODCI) at 2 Weeks	PODCI domain scores are standardized from 0 to 100, where higher scores indicate better function/well-being. The metric is change from baseline to 2 weeks	Baseline and 2 weeks
Change From Baseline in Pediatric Function as Measured by the Pediatric Outcomes Data Collection Instrument (PODCI) at 3 Months	PODCI domain scores are standardized from 0 to 100, where higher scores indicate better function/well-being. The metric is change from baseline to 3 months.	Baseline and 3 months
Change From Baseline in Knee Function as Measured by the KOOS-Child at 2 Weeks (Osgood-Schlatter Subgroup)	KOOS-Child subscale scores are transformed to a 0 to 100 scale, where higher scores indicate better knee status (fewer symptoms/better function). The metric is change from baseline to 2 weeks, assessed in the Osgood-Schlatter subgroup only.	Baseline and 2 weeks
Change From Baseline in Knee Function as Measured by the KOOS-Child at 3 Months (Osgood-Schlatter Subgroup)	KOOS-Child subscale scores are transformed to a 0 to 100 scale, where higher scores indicate better knee status. The metric is change from baseline to 3 months, assessed in the Osgood-Schlatter subgroup only.	Baseline and 3 months
Change From Baseline in Foot/Ankle Function (OxAFQ-C) at Post-intervention (2 weeks), Sever Subgroup Only	OxAFQ-C domains 0-100 (higher=better). Metric: change from baseline to ≈2 weeks. Assessed only in Sever participants.	Baseline and 2 weeks
Change From Baseline in Foot/Ankle Function (OxAFQ-C) at Follow-up (3 months), Sever Subgroup Only	OxAFQ-C domains 0-100 (higher=better). Metric: change from baseline to 3 months.	Baseline and 3 months

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change From Baseline in Ultrasound Features of the Symptomatic Apophysis at 2 Weeks	Musculoskeletal ultrasound of the index symptomatic apophyseal site using a standardized acquisition protocol (high-frequency linear probe; fixed patient position). Predefined features will be graded on ordinal scales and summed into a prespecified composite "ultrasound severity score" (higher = greater abnormality). Features include: (1) apophyseal fragmentation/irregularity, (2) tendon insertion thickening, (3) hypoechogenicity, (4) bursal fluid/soft-tissue swelling. Metric: change in composite score from baseline to 2 weeks.	Baseline and 2 weeks
Change From Baseline in C-Reactive Protein at 2 Weeks	Serum concentration of C-reactive protein (CRP), measured using enzyme-linked immunosorbent assay (ELISA) per protocol. Metric: change from baseline to 2 weeks. Unit of measure: per ELISA kit manufacturer instructions (e.g., mg/L); values will be converted to a single standard unit for CRP prior to analysis.	Baseline and 2 weeks
Change From Baseline in Interleukin-6 at 2 Weeks	Serum concentration of interleukin-6 (IL-6), measured using enzyme-linked immunosorbent assay (ELISA) per protocol. Metric: change from baseline to 2 weeks. Unit of measure: per ELISA kit manufacturer instructions (e.g., pg/mL); values will be converted to a single standard unit for IL-6 prior to analysis.	Baseline and 2 weeks.
Change From Baseline in Tumor Necrosis Factor-Alpha at 2 Weeks	Serum concentration of tumor necrosis factor-alpha (TNF-α), measured using enzyme-linked immunosorbent assay (ELISA) per protocol. Metric: change from baseline to 2 weeks. Unit of measure: per ELISA kit manufacturer instructions (e.g., pg/mL); values will be converted to a single standard unit for TNF-α prior to analysis.	Baseline and 2 weeks.
Change From Baseline in C-Terminal Cross-Linked Telopeptide of Type II Collagen at 2 Weeks	Serum concentration of C-terminal cross-linked telopeptide of type II collagen (CTX-II), measured using enzyme-linked immunosorbent assay (ELISA) per protocol. Metric: change from baseline to 2 weeks. Unit of measure: per ELISA kit manufacturer instructions (e.g., pg/mL or ng/mL); values will be converted to a single standard unit for CTX-II prior to analysis.	Baseline and 2 weeks
Change From Baseline in Type II Collagen Cleavage Neoepitope at 2 Weeks	Serum concentration of type II collagen cleavage neoepitope (C2C), measured using enzyme-linked immunosorbent assay (ELISA) per protocol. Metric: change from baseline to 2 weeks. Unit of measure: per ELISA kit manufacturer instructions (e.g., pg/mL or ng/mL); values will be converted to a single standard unit for C2C prior to analysis.	Baseline and 2 weeks.
Change From Baseline in C-Propeptide of Type II Procollagen at 2 Weeks	Serum concentration of C-propeptide of type II procollagen (CPII), measured using enzyme-linked immunosorbent assay (ELISA) per protocol. Metric: change from baseline to 2 weeks. Unit of measure: per ELISA kit manufacturer instructions (e.g., pg/mL or ng/mL); values will be converted to a single standard unit for CPII prior to analysis.	Baseline and 2 weeks.
Treatment Expectancy and Credibility (TEC-C / TEC-P) at Baseline (Pre-intervention)	Treatment expectancy and credibility will be assessed in the child and parent/caregiver using pediatric versions of the Treatment Expectancy and Credibility measure (TEC-C and TEC-P). The child and caregiver complete the questionnaires independently (without influence on each other's responses). Scores are derived per instrument instructions (higher scores indicate greater expectancy/credibility).	Pre-intervention (baseline), prior to the first treatment session and prior to functional testing.
Change From Baseline in Cartilage Oligomeric Matrix Protein at 2 Weeks	Serum concentration of cartilage oligomeric matrix protein (COMP), measured using enzyme-linked immunosorbent assay (ELISA) per protocol. Metric: change from baseline to 2 weeks. Unit of measure: per ELISA kit manufacturer instructions (e.g., ng/mL); values will be converted to a single standard unit for COMP prior to analysis.	Baseline and 2 weeks.
Change From Baseline in Procollagen Type I N-Terminal Propeptide at 2 Weeks	Serum concentration of procollagen type I N-terminal propeptide (PINP), measured using enzyme-linked immunosorbent assay (ELISA) per protocol. Metric: change from baseline to 2 weeks. Unit of measure: per ELISA kit manufacturer instructions (e.g., ng/mL); values will be converted to a single standard unit for PINP prior to analysis.	Baseline and 2 weeks
Change From Baseline in Beta C-Terminal Telopeptide of Type I Collagen at 2 Weeks	Serum concentration of beta C-terminal telopeptide of type I collagen (β-CTX), measured using enzyme-linked immunosorbent assay (ELISA) per protocol. Metric: change from baseline to 2 weeks. Unit of measure: per ELISA kit manufacturer instructions (e.g., pg/mL or ng/mL); values will be converted to a single standard unit for β-CTX prior to analysis.	Baseline and 2 weeks.
Change From Baseline in Tartrate-Resistant Acid Phosphatase 5b at 2 Weeks	Serum concentration or activity of tartrate-resistant acid phosphatase 5b (TRAP-5b), measured using enzyme-linked immunosorbent assay (ELISA) per protocol. Metric: change from baseline to 2 weeks. Unit of measure: per ELISA kit manufacturer instructions (e.g., U/L or ng/mL); values will be converted to a single standard unit for TRAP-5b prior to analysis.	Baseline and 2 weeks
Change From Baseline in Osteocalcin at 2 Weeks	Serum concentration of osteocalcin, measured using enzyme-linked immunosorbent assay (ELISA) per protocol. Metric: change from baseline to 2 weeks. Unit of measure: per ELISA kit manufacturer instructions (e.g., ng/mL); values will be converted to a single standard unit for osteocalcin prior to analysis.	Baseline and 2 weeks.
Change From Baseline in Bone-Specific Alkaline Phosphatase at 2 Weeks	Serum bone-specific alkaline phosphatase (BAP), measured per protocol (assay name per project documentation; if "Ostase/Ostease" is the assay, write it exactly as used by the lab). Metric: change from baseline to 2 weeks.	Baseline and 2 weeks.
Change From Baseline in Total Serum Calcium at 2 Weeks	Total serum calcium concentration, measured using laboratory assay per protocol. Metric: change from baseline to 2 weeks. Unit of measure: per laboratory assay (e.g., mmol/L or mg/dL); values will be converted to a single standard unit for total serum calcium prior to analysis if required.	Baseline and 2 weeks.
Change From Baseline in 25-Hydroxyvitamin D at 2 Weeks	Serum 25-hydroxyvitamin D (25(OH)D), measured using laboratory assay per protocol. Metric: change from baseline to 2 weeks. Unit of measure: ng/mL (or nmol/L) per laboratory assay; values will be converted to a single standard unit for 25(OH)D prior to analysis if required.	Baseline and 2 weeks.
Change From Baseline in 1,25-Dihydroxyvitamin D at 2 Weeks	Serum 1,25-dihydroxyvitamin D (1,25(OH)₂D), measured using laboratory assay per protocol. Metric: change from baseline to 2 weeks. Unit of measure: pg/mL (or pmol/L) per laboratory assay; values will be converted to a single standard unit for 1,25(OH)₂D prior to analysis if required.	Baseline and 2 weeks.
Change From Baseline in Bone-Specific Alkaline Phosphatase at 2 Weeks	Serum concentration or activity of bone-specific alkaline phosphatase (BAP), measured using enzyme-linked immunosorbent assay (ELISA) per protocol (assay name per project documentation, if applicable). Metric: change from baseline to 2 weeks. Unit of measure: per ELISA kit manufacturer instructions (e.g., U/L or µg/L); values will be converted to a single standard unit for BAP prior to analysis.	Baseline and 2 weeks.

Collaborators and Investigators

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

Study record dates

Study Major Dates

• Study Start (Actual): March 1, 2026
• Primary Completion (Estimated): February 1, 2027
• Study Completion (Estimated): February 1, 2029

Study Registration Dates

• First Submitted: February 1, 2026
• First Submitted That Met QC Criteria: February 28, 2026
• First Posted (Actual): March 3, 2026

Study Record Updates

• Last Update Posted (Actual): March 17, 2026
• Last Update Submitted That Met QC Criteria: March 14, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: Photobiomodulation; Low-Level Laser Therapy; Apophysitis; Heel Pain; Osgood-Schlatter Disease; Traction Apophysitis; Tibial Tubercle Pain
• Additional Relevant MeSH Terms: Bone Diseases; Musculoskeletal Diseases; Osteochondrosis; Therapeutics; Laser Therapy; Phototherapy; Low-Level Light Therapy
• Other Study ID Numbers: KB/591/2025-2026; 71-01428 (Other Identifier: Young Creator of Science" grant program, Excellence Initiative - Research University, Medical University of Gdańsk); DEC-2025/09/X/NZ7/01758 (Other Grant/Funding Number: National Science Centre, Poland (NCN) - MINIATURA 9 // Narodowe Centrum Nauki (NCN) - MINIATURA 9)

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 trial, along with a data dictionary, will be made available to qualified researchers. Data will include baseline characteristics, group allocation (coded), outcome measures, and adverse events. Data will be shared after publication of the primary results and will remain available for at least 5 years. Access will be provided upon reasonable request and approval of a methodologically sound proposal, with a signed data use agreement, and only for non-commercial research purposes. Supporting documents (protocol and statistical analysis plan) will be shared.

Drug and device information, study documents

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