Bilateral femoral neck fractures in pregnancy suggestive of transient osteoporosis of the hip in a patient with hyperparathyroidism: a case report

Atraumatic bilateral femoral neck fractures are rare, especially in younger patients and those without significant comorbidities. However, pregnant individuals appear to be at increased risk due to normal physiological changes in calcium balance, leading to transient osteoporosis of the hip. In these individuals, calcium and bone mineral density are generally decreased, reflecting the calcium demands of the developing fetus. Therefore, peripartum non-osteoporotic bilateral femoral neck fractures sustained remain a rare presentation. A 31-year-old patient presented with worsening hip pain; imaging studies revealed bilateral femoral neck fractures. A complicated birth requiring specialized maneuvers 11 months prior resulted in moderate hip pain, and a single step down from the bottom rung of a ladder approximately 7 months after the delivery initiated acute exacerbation of the hip pain. Orthopedic evaluation determined that the patient would benefit most from the surgical fixation of both femoral necks with an arthroplasty on the right and a dynamic hip screw on the left. Rheumatologic evaluation of the patient revealed no relevant risk factors for osteoporosis other than suboxone use, tobacco use, and low levels of vitamin D. A DXA scan was unremarkable, and interestingly, the only notable laboratory findings were markedly increased parathyroid hormone levels with a slight increase in calcium. Pregnant patients with high serum levels of parathyroid hormone might be at risk for atraumatic hip fractures regardless of serum calcium levels, particularly when maneuvers that put stress on the femoral neck are employed. This case demonstrates the importance of increased clinical suspicion of hip fractures and evaluation for hyperparathyroidism in a patient presenting with atypical hip pain immediately following labor.