Bilateral neck of femur fractures are associated with high-energy trauma, electroconvulsive and pharamacoconvulsive therapy, and other convulsive seizures.

A 67-year-old woman with chronic renal failure developed a witnessed tonic–clonic seizure, lasting about 1 min. She was placed in the recovery position during the seizure and was not restrained. During the tonic phase, her hips were flexed and abducted. She sustained no external trauma during the seizure. On the fifth postseizure day, she was found to have bilateral subcapital neck of femur fractures (figure 1) and subsequently underwent successful bilateral hip hemiarthroplasty procedures (figure 2).

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Figure 1

Preoperative radiograph showing bilateral subcapital neck of femur fractures.

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Figure 2

Postoperative radiograph showing bilateral hip hemiarthroplasty implants.

Most bilateral seizure-induced hip fractures were previously related to electroconvulsive therapy, performed before muscle relaxants and general anaesthesia became routine during this procedure.1 ,2 Acetabular fractures with central dislocations become more likely if the hips are adducted. In this position, the joint reaction force is directed at the medial wall of the acetabulum, which then fractures. Further forceful contraction causes the femoral head to dislocate through the fractured acetabulum. By contrast, when the hips are flexed and abducted, the proximal femur impinges off the acetabular rim. This levering effect results in a fracture of the femoral neck.

Certain medical conditions that diminish bone strength further increase the possibility of hip fracture. Patients with chronic renal failure may develop renal osteodystrophy; hypocalcaemic tetanic convulsions in these patients may lead to proximal femur fracture. Elderly patients who cannot walk, and those on long-term corticosteroid therapy also have diminished bone strength and so are at increased risk. Additionally, transient osteoporosis can develop during pregnancy, increasing the risk of hip fracture during pregnancy-related seizures.

Neurologists are well aware of the risk of vertebral body fractures and posterior shoulder dislocations during convulsive seizures, but should also recognise the risk of fracture to the proximal femur and acetabulum. A displaced neck of femur fracture in a young adult represents a surgical emergency. Patients need early fracture reduction and fixation to try to avoid avascular necrosis of the femoral head. Failure to investigate postseizure hip or groin pain with early radiographs may delay diagnosis and result in osteoarthritis, poor functional outcome and total joint arthroplasty. This has important implications in younger adults where a major objective is the preservation of the native femoral head rather than joint replacement.