Disclosures: Ella C. D’Amico, MD: No financial relationships or conflicts of interest

Case Diagnosis: 17-year-old male lacrosse player with multifocal bone stress injuries.

Case Description or Program Description: A 17-year-old male lacrosse player with a history of depression and acne vulgaris on isotretinoin presented during his fall off-season with one year of insidious onset bilateral knee pain. After the summer off, his pain resumed with fall training, but he continued to play. Pain was sharp, exacerbated with activity, and improved with rest. It localized to the anteromedial knee and was worse on the left. He denied trauma, swelling, locking, or weakness. On examination, he had mild tenderness to palpation at the left medial patellar facet only. No effusion. Ligamentous and meniscal examination maneuvers were negative. There was dynamic valgus with single leg squat bilaterally. He began physical therapy for patellofemoral pain, but his symptoms progressed. MRI showed multifocal bone stress injuries in the left distal femur and proximal tibia (fracture line present) and right distal femur and proximal fibula.

Setting: Outpatient Sports Medicine Clinic

Assessment/Results: He was non-weight bearing for eight weeks in a wheelchair with resolution of pain and initiation of isometric exercises before being cleared for weight-bearing and progressive strengthening. He was referred to endocrinology where workup revealed vitamin D insufficiency and an appropriately low PTH in the setting of calcium supplementation. DEXA and bone scan were age-appropriate. He was prescribed calcium and vitamin D supplements. Isotretinoin had been discontinued given improved acne.

Discussion (relevance): Bilateral stress injuries are rare and additionally unusual in a healthy teenager. While studies show that isotretinoin leads to impaired osteoblast and osteoclast function and decreased fracture healing, a literature review reveals no case reports of stress fracture related to the medication. Studies also suggest isotretinoin attenuates vitamin D efficacy, further explaining fracture risk in our patient with vitamin D insufficiency.

Conclusions: Bone stress injury should be considered in patients with focal musculoskeletal pain on isotretinoin.

Level of Evidence: Level V

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/multifocal-bone-stress-injuries-in-a-17-year-old-male-lacrosse-player-on-isotretinoin-a-case-report/