Bilateral Femoral Neck Stress Fractures in a Patient with Severe Coxa Vara, Morbid Obesity and Osteomalacia: A Case Report

Femoral neck stress fractures are rare and encompass 5% of all stress fractures among the young people. The bilateral cases are very rare. Coxa vara deformity and morbid obesity are some of the predisposing factors for bilateral stress fractures. The decline of neck-shaft angle will result in an increase and concentration of stress force in femoral neck giving rise to fracture. This report introduced a 35-year-old man with severe coxa vara deformity with an angle of 100 neck-shaft who had a bilateral femoral neck stress fracture and severe obesity [body mass index (BMI) > 35 kg/m2]. The femoral neck stress fracture was a tension-type occurred due to stress in coxa vara. Based on laboratory findings, his vitamin D deficiency was severe (8.9 ng/mL) but his PTH and phosphorus levels were normal. Regarding vitamin D deficiency and previous femoral deformity, the possibility of osteomalacia in adolescence period was raised. Bilateral valgus sub-trochanteric osteotomy and fixation with a dynamic hip screw (DHS) were performed. After three months, the patient restored his walking ability and weight bearing. Valgus sub-trochanteric osteotomy and fixation with DHS are useful methods in coxa vara deformity concomitant with stress fractures and can modify the neck-shaft angle.