Medical Student Mayo Clinic Alix School of Medicine Scottsdale, Arizona, United States
Case Diagnosis: Non-displaced Right Fibular Head Fracture
Case Description: A 45-year-old man presented with a 3-week history of posteromedial knee pain after a hyperextension-type injury while riding a One-wheel. Physical exam exhibited pain along the posteromedial knee with palpation, valgus testing, medial McMurray’s testing and exhibited guarding of his hamstrings. This appeared consistent with medial meniscus injury, MCL injury and/or proximal medial calf strain. Interestingly, on x-ray and MRI it was determined that there was an isolated non-displaced right fibular head fracture with no involvement of proximal tibiofibular joint or surrounding soft tissue.
Symptoms were treated conservatively with physical therapy, bracing, and activity limitations. After one month of conservative treatment, a curve beam CT indicated progressive healing and unchanged position of the fracture.
Discussions: An isolated fibular head fracture is rare but typically presents as an avulsion fracture and usually as a result of a motor vehicle accident. This case indicates an isolated fibular head fracture that is non-displaced, as a result of a hyperextension-type injury which has not previously been described. There is an unusual presentation with pain presenting posteromedially for this fibular fracture as opposed to the lateral aspect of the knee, which is more common. Guarding of the hamstrings may have been the clearest indication of the location of the injury due to the insertion of the biceps femoris onto the fibular head.
Conclusions: A non-displaced fibular head fracture may be considered in a differential diagnosis in a patient with a hyperextension-type injury with symptoms that may otherwise be attributed to a medial injury to the intra-articular tissue of the knee. In cases where more common injuries do not align well with the patient’s history and physical exam, we recommend that physicians rule-out this fracture with standard imaging modalities such as plain radiograph or MRI without contrast of the knee.
