Young patients with hip fracture: a population-based study of bone mass and risk factors for osteoporosis.

Introduction: Hip fracture in young patients is rare. The present study was aimed to clarify the comorbidity pattern and reveal relevant risk factors for osteoporosis and fracture in this patient group.

Materials And Methods: Using electronic diagnosis registers and lists of the operating theatres for the Oslo hospitals, patients with new hip fracture during two 1-year periods from May 1994 through April 1995 and from May 1996 through April 1997 were identified. All patients age 20-49 years at the time of fracture were included (n=49), and a detailed medical history was recorded. Thirty-two of the patients volunteered for examination and completed a questionnaire and interview to reveal risk factors for osteoporosis. Data from the Oslo Health Study served as reference material. Bone mineral density (BMD) was measured using dual x-ray absorptiometry, and Z-scores were calculated using healthy subjects from Oslo as reference.

Results: Of the patients identified, the median age was 40 years (range 25-49), and 63% were men. In 65% of the patients, the fracture occurred after a fall at the same level, in 16% it occurred after a fall from a higher level, and in 18% it occurred in a traffic accident. Twenty percent of the patients had a history of alcohol or drug abuse, 39% had neuromuscular diseases, and 12% had endocrine diseases. The patients examined had significantly more risk factors for osteoporosis than the reference population. The BMD expressed as Z-score for L2-4 was -1.0+/-0.9 (mean +/- SD; p<0.001), for femoral neck was -1.5+/-1.0 (p<0.001), and for total body was -1.3+/-1.1 (p<0.001). BMD was significantly lower than in controls for patients sustaining low-energy and high-energy trauma. There was a negative correlation between the total number of risk factors and BMD for lumbar spine (r=-0.35, p<0.05), femoral neck (r=-0.37, p=0.04), and total body (r=-0.55, p=0.001), respectively.

Conclusions: The majority of the young patients with hip fracture have a history of low-energy trauma, comorbidity predisposing for falls or decreased bone strength, as well as several risk factors for osteoporosis. The BMD was significantly lower than in the reference population regardless of the trauma mechanism.