Measurement Of Cancellous Bone Strength And Difference Between Femoral Head With Femoral Neck Fracture And Non-traumatic Osteonecrosis In Male Patients

Objective:Cancellous bone mass and bone quality of men with Femoral neck fracture and non-traumatic femoral head necrosis were measured by several usual evaluation to obtain the paremeter of bone strength.Then we investigated the differences of bone strength between Chinese men with femoral neck fractures and non-traumatic femoral head necrosis to figure out the impacts of bone mass and bone quality on femoral neck fractures, interpret the partial inherent factors of the phenomenon that patients with femoral neck fracture on clinical were proned to fracture comparing with patients of femoral head necrosis and comprehend the relationship of avascular necrosis and bone mass, bone quality indirectly. It might offer the scientific basis for further study of the pathogenesis of femoral head necrosis.Methods:Human femoral heads were obtained from 30 male patients with femoral neck fracture (n=13, mean age 64±9.73 years, age 48-82 years) and non-traumatic femoral head necrosis (n=17, mean age 61.94±13.26, ages 28-75 years) according to medical history, X-ray examination and pathological diagnosis. The femoral head was taken in two hours after hip replacement, then three 6×6×7mm sized cancellous bone were divided from the femoral head in fixed positions after removing cortical, numbered it. The DXA, micro CT, ash weight, mechanical experiments were performed to obtain parameters as bone mass, micro-structural parameters, inorganic and organic parameters and biomechanical parameters. The the differences in bone mass and bone quality of fracture group and the necrosis group were analyzed for the bone mechanical strength differences between the two different diseases.Results:Compared the femoral neck fracture group with the avascular necrosis group, there was a significantly decreased in area bone mineral density of trabecular bone(0.16±0.04 VS 0.20±0.05 mg/mm2), volume bone mineral density (193.75±83.88 VS 298.05±17.63 mg/mm3), trabecular number (1.46±0.30 VS 1.74±0.40#/mm3), bone volume fraction (0.22±0.07 VS 0.33±0.09%), the maxium compressing force (152.43±106.25 VS 426.56±243.15 N) (P<0.05) while the surface area volume ratio (13.94±3.34 VS 11.04±3.12 mm-1), fatigue compress height (2.12±1.64 VS 0.98±1.34 mm) increased significantly (P<0.05). Trabecular thickness, trabecular spacing, structure model index, degree of anisotropy, trabecular connectivity density, volume bone mineral content, volume collagen content, percentage of ash content, percentage of collagen content were not found significances.Conclusion:It showed that decreased inherent bone strength was another factor of increased risk incident of fracture besides the additional force. The increase bone mass and bone quality in non-traumatic femoral head necrosis group indicated that avascular necrosis had less influence in bone strength, it might explain the reason of non-traumatic femoral bone necrosis accompanied with little femoral neck fracture on clinic.