Axial compression in femoral neck osteotomies. A biomechanic study in human cadaver hips

The risk of applying compression to a sliding-screw-plate osteosynthesis in the treatment of femoral neck fractures was evaluated in an experimental study of 40 femoral neck osteotomies. Ten pairs of bones from autopsied women between 70 years and 79 years of age were compared to 10 pairs of bones from autopsied women of more than 80 years of age. The compression was applied intermittently but measured continuously. The results showed a diphasic curve. When the maximum axial compression force was reached, any attempt to apply further compression resulted in a rapid fall in pressure at the site of the osteotomy. The median of the maximum axial compression force was 971 N, ranging from 275 N to 1756N. The maximum axial compression forces were significantly lower in bones from women of more than 80 years of age compared to bones from women in the seventh decade. The clinical implication of the study is that compression of femoral neck fractures by a sliding-screw-plate system may be hazardous in patients with brittle bone, e.g. women over 80 years of age.