611 - Distal Diaphyseal Femoral Fracture in a Young Female Marathon Runner

Right transverse diaphyseal femur fracture and right medial meniscus tear. 

Case Description: A 33-year-old female with a past medical history of anxiety and ADHD presented to the emergency department (ED) with a one-day history of severe atraumatic right knee pain sustained while completing a marathon. She was initially diagnosed with a quadriceps tendon rupture at an onsite medical station and urgent care despite successfully completing a quadriceps set exercise, and was denied radiographic imaging. Her ED assessment revealed an inability to bear weight on her right leg, limited knee extension, a normal neurological exam, and no malignancy or metabolic abnormalities. Diagnostic imaging revealed a transverse multi-fragment fracture through the distal shaft of her right femur and a vertical tear through the knee cartilage. She underwent a retrograde intramedullary nailing procedure the next day and was discharged without complication. A post-procedural DEXA scan two weeks post-surgery showed age-appropriate bone mineral density (BMD) and normal trabecular architecture, with no signs of bone fragility.

Discussions: Diaphyseal femur fractures in young female athletes are rare, typically arising from accidental trauma or repetitive mechanical strain. Well-established risk factors for diaphyseal fractures include the female athlete triad (low BMD, menstrual dysfunction, inadequate calorie intake), metabolic bone disease, and sudden increases in training volume. Additionally, diaphyseal fractures most commonly occur at the anterior shaft of the femur. The fracture’s unusual location and absence of common risk factors make this case rare, emphasizing the need for careful clinical assessment to avoid delays in diagnosis.

Conclusions: This case underscores the importance of maintaining a high index of suspicion for atypical orthopedic injuries in initial assessments, even in patients with unremarkable medical histories.