Photobiomodulation Therapy for the Treatment of Lower Extremity Stress Fractures in a Military Training Setting

The goal of this clinical trial is to compare photobiomodulation therapy (PBMT) in addition to standard of care in the treatment of tibial and metatarsal bone stress injuries in a military training setting.

Participants will all receive usual care and also be randomized to either active or sham photobiomodulation therapy. Effectiveness will be assessed based on time to return to duty and measures of pain and function.

* Participants will receive care for a maximum of 6 weeks.
* Participants will have follow-up through 4 months (or graduation/dismissal from training, whichever comes first).

Trainees with a diagnosis of medial tibial or metatarsal bone stress injuries/stress fracture will be recruited. Patients that consent and enroll will be randomized to receive standard of care physical therapy with (1) photobiomodulation therapy (PBMT) or (2) sham PBMT. Patients will receive treatment 3x per week for up to 6 weeks. The primary outcome will be the time to return to duty. Secondary outcomes will include additional time points (3-week, 6-week, 4-month) and Patient-Reported Outcomes Measurement Information System (PROMIS®) measures of pain and function, lower extremity imaging and various other measures outlined in the "Outcome Measure" section. Participants will be asked to report any mineral supplementation and to record daily activity in a log. Survival analysis will be used to evaluate return to duty between treatment arms with censoring beyond 4 months.

Longitudinal hierarchical/multilevel models with random effects will be used to evaluate differences between treatment arms for the relevant outcome measures. Sensitivity analyses will be conducted predicting change in measures at the final follow-up relative to baseline, and will use linear generalized additive models.

Eligibility Criteria:
Inclusion Criteria:

* between ages 17-64 (inclusive) years old
* Currently completing Advanced Individual Training (AIT) training at Fort Sam Houston and at least 6 weeks prior to graduation
* Clinical diagnosis of metatarsal or medial tibial bone stress injury/stress fracture (unilateral or bilateral) by a healthcare provider based on accepted diagnostic criteria, with diagnostic imaging confirmation
* Able to read and understand English language for consent purposes
* Able to commit to study intervention and follow-up

Exclusion Criteria:

* Stress fracture to tibia that is not medial (e.g., anterior) or any location other than 5th metatarsal or medial tibia
* Has already become a severe non-union bone stress injury/fracture
* Received dry needling within the past 4 weeks
* Received Platelet Rich Plasma (PRP) injection, corticosteroid injection, or prolotherapy within the past 3 months
* Diagnosis of neuropathy affecting sensation to pain
* Current or chronic sciatica (lumbosacral radiculopathy) resulting in chronic or intermittent lower extremity pain, numbness, or tingling (all below the knee)
* Current or previous diagnosis of eating disorder (e.g., bulimia nervosa, anorexia nervosa, disordered eating, or other eating disorder not specified)
* Diagnosis of porphyria (light induced allergy) or photosensitive eczema
* Diagnosis of autoimmune disease (e.g., Lupus)
* Albinism
* Current use of anti-inflammatory steroids due to increased risk of Bone Stress Injury (BSI) with the past two weeks
* Current use of medications associated with sensitivity to heat or light in the past five days (e.g., amiodarone, chlorpromazine, doxycycline, hydrochlorothiazide, nalidixic acid, naproxen, piroxicam, tetracycline, thioridazine, voriconazole)
* Previous or current (within the past 2 years) use of Depo Provera
* Current use of pacemaker
* Tattoo in the area of treatment due to sensitivity to Photobiomodulation Therapy (PBMT)
* Concurrent participation in another research study receiving treatment for metatarsal or medial tibial bone stress injury/stress fracture
* Currently pregnant or plan to become pregnant during intervention period (safety of PBMT not established in pregnancy)
* Current diagnosis or symptoms of amenorrhea (≥ 6 months without a menstrual period) or oligomenorrhea (only 4-9 menstrual periods in a year)