Sham no Better than Active Low-level Laser Therapy in Military Trainee Graduation Rates after Metatarsal or Tibial Stress Fractures- MHSRS 2026

d rhon, n parsons, t greenlee, e metzger, s hole, n hager

Abstract accepted for poster presentation at the 2026 Military Health System Research Symposium (MHSRS)

Background: Lower extremity stress fractures are one of the most consequential injuries in military service members, disproportionately affecting trainees. They represent a substantial source of morbidity, training disruption, and health care utilization, with incidents as high as 40% reported in trainees. The purpose of this study was to compare the effectiveness of active versus sham low-level laser therapy (LLLT) on graduation rates in military trainees with lower extremity stress fractures. The secondary aims were to compare pain and physical function outcomes.

Methods: Participants were trainees at the Medical Education and Training Campus, San Antonio, Texas, with an MRI-confirmed metatarsal and/or tibial stress fracture, enrolled between June 2023 and November 2024. All participants received standard-of-care treatment and were randomized to either active or sham LLLT. The primary outcome was on-time graduation at four months, and secondary outcomes included the Defense and Veterans Pain Rating Scale (DVPRS) and Lower Extremity Functional Scale (LEFS), also at four months. Changes in bone healing were assessed on magnetic resonance imaging from baseline to four months.

Results: The mean age (SD) was 23.7 (4.7) years, 54.4% female, and 80.6% in the US Army. In 46.6% of the cohort, both extremities were affected; tibia involvement was 69.9% and metatarsal 30.1%, with severity of stress fractures ranging from grade I to IV. Only 36.9% of participants graduated without delays. There was no statistically significant difference in graduation rates between sham or active treatment groups. Furthermore, sex, laterality, and stress fracture location did not predict successful graduation rates. Pain (mean difference[95CI] DVPRS -0.7312 [-2.308,0.8456]) and function (mean difference[95CI] LEFS 5.8101 [-8.0288,19.649]) were also not significantly different.

Conclusion: Graduation rates, pain intensity, and physical function did not differ significantly between military trainees who received LLLT and those who received sham. Given the substantial resource investment, the routine use of LLLT may impose unnecessary burdens on both trainees and healthcare systems and is not recommended.