Delayed Diagnosis of Osteonecrosis of the Femoral Head After a Minor Running Injury in a Healthy 28-Year-Old Man: A Case Report.

Osteonecrosis (avascular necrosis, AVN) of the femoral head in young adults is typically associated with high-energy trauma, corticosteroids, or alcohol abuse. Early disease is typically radiographically occult. We report a case of a previously healthy 28-year-old man who developed persistent right hip pain following a minimal twisting trauma while running. Initially obtained hip radiographs at an outside facility immediately following the trauma were interpreted as normal; the pain was considered to represent a soft tissue injury, and the patient underwent only a brief course of physical therapy and did not follow up further with the normal radiographs. However, the pain continued for seven months and was still preventing him from running. Therefore, the patient presented to our department, and a pelvic radiograph demonstrated mild osteoarthritic change of the right hip joint and features suspicious for osteonecrosis of the right femoral head. Further imaging with MRI confirmed osteonecrosis of the right femoral head with bone marrow edema, representing Ficat-Arlet stage II disease, with mild osteoarthritic change, chondromalacia, synovitis, and a large joint effusion in the right hip joint; no musculotendinous abnormalities were identified. The patient was referred to an orthopedic surgeon who recommended operative treatment. This case demonstrates that osteonecrosis of the femoral head can present in young healthy adults in the setting of seemingly trivial trauma, and normal early radiographs do not rule out the diagnosis. As a single case report, this does not establish causality.