Internal Fixation

Clinical Manifestations of Bilateral Femoral Neck Fractures

Bilateral femoral neck fractures are considered a rare entity in the general population. While these injuries are frequently linked to high-energy trauma, medical findings suggest they can also occur in association with metabolic or bone diseases, epilepsy, or other significant physiological stressors. The simultaneous fracturing of both femoral necks represents a distinct clinical challenge due to the unusual nature of the injury mechanism.

The clinical presentation of bilateral femoral neck fractures (BFNF) in adolescents presents unique orthopedic complexities. Unlike unilateral fractures, BFNF necessitates a comprehensive surgical strategy to stabilize both hip joints, often requiring simultaneous internal fixation. Orthopedic surgeons managing these cases must prioritize the preservation of the blood supply to the femoral head to mitigate the risk of avascular necrosis (AVN), a condition where bone tissue dies due to interrupted blood flow. In adolescent populations, the risk of AVN is a primary driver in surgical decision-making, as the long-term consequences of hip joint degradation are significantly more pronounced in younger patients than in adults.

Diagnostic protocols for these injuries typically involve a multi-modal imaging approach. While plain-film radiography serves as the initial screening tool to identify gross displacement, clinicians frequently employ Computed Tomography (CT) to evaluate the specific fracture morphology and the degree of cortical involvement. In cases where fractures appear stable on X-ray but clinical suspicion remains high, Magnetic Resonance Imaging (MRI) is utilized to detect bone marrow edema or subtle, non-displaced fracture lines that could lead to future instability.

Divergent Patient Profiles in Medical Literature

Medical reports highlight two distinct adolescent case studies involving these injuries, showcasing different underlying medical contexts. In one documented case, a 17-year-old male with cerebral palsy and developmental delays experienced a grand mal seizure. This patient had been receiving treatment with the antiseizure medication valproic acid for approximately 10 years. During the seizure, the patient sustained spontaneous bilateral femoral neck fractures.

The decade-long administration of valproic acid in this patient provides a significant clinical variable. Pharmacological research has investigated the correlation between long-term anticonvulsant therapy and bone mineral density (BMD). Studies published in neurological and orthopedic journals have noted that certain antiseizure medications can influence bone metabolism, potentially contributing to decreased bone mass. In a patient with cerebral palsy, where physical activity levels and bone loading may already be altered, the pharmacological profile of valproic acid may play a role in the skeletal vulnerability observed during seizure-induced stress.

A separate case study involves a 16-year-old boy who was previously described as healthy. This adolescent sustained simultaneous bilateral femoral neck fractures following a single, first-time seizure. Medical analysis identified the seizure as being secondary to hypocalcemia, a condition characterized by low calcium levels in the blood.

The metabolic trigger in this case involves acute calcium homeostasis disruption. Clinical literature identifies that rapid fluctuations in serum calcium can induce neuromuscular hyperexcitability and tetany. In the context of a first-time seizure, the sudden onset of intense, involuntary muscle contractions serves as the primary mechanical force. This case emphasizes that even in previously healthy adolescents, acute metabolic shifts can produce the physiological intensity required to cause spontaneous skeletal failure.

Seizure-Induced Mechanisms of Injury

The mechanical cause of these fractures involves the intense physical movements or muscle contractions characteristic of seizure activity. In the case of the 17-year-old, the seizure occurred in a patient already managing the physical limitations and sequelae of cerebral palsy. In the case of the 16-year-old, the seizure was driven by a sudden metabolic shift involving hypocalcemia.

Biomechanical analysis suggests that the tonic-clonic phase of a seizure generates significant axial loading and torsional stress on the femoral neck. The simultaneous, forceful contraction of the large muscle groups of the pelvic girdle—specifically the iliopsoas, rectus femoris, and gluteal muscles—creates a lever effect. This intense muscular activity can generate forces that exceed the structural threshold of the femoral neck, especially if the bone density is compromised by underlying medical conditions or long-term medication use.

These instances demonstrate that seizure-induced muscle activity can generate sufficient force to cause severe skeletal fractures without the requirement for external high-impact force. The medical community continues to study these cases to better understand the relationship between seizure-related muscle contractions and spontaneous bone failure in vulnerable or metabolically compromised populations.

Orthopedic Management and Surgical Considerations

Surgical intervention for adolescent bilateral femoral neck fractures focuses on internal fixation to maintain anatomical alignment and promote healing. Standard orthopedic protocols often utilize multiple cannulated screws to stabilize the fracture site. For adolescents, surgeons aim to avoid total hip arthroplasty (hip replacement) whenever possible, as preserving the native joint and the growth plate is critical for long-term skeletal development. However, the dual nature of these fractures complicates the postoperative period, requiring carefully managed weight-bearing protocols and intensive physical therapy to prevent non-union or malunion of the bone.

Consult your healthcare provider for any medical concerns or questions regarding seizure management and bone health.