The Weight-Rearing Capacity of Structural Elements in Femoral Necks

1. Up to the age about 60 the resistance of the femoral neck to compression forces is the same on the left and the right side. After that age the mechanical resistance may decrease considerably on one side. This might be of clinical significance in the explanation of neck fractures.

2. The inferior cortical layer of the femoral neck has a weight-bearing capacity of 40 per cent in adults.

3. The superior cortical layer has a weight-bearing capacity of 20 per cent.

4. The superior and inferior cancellous tissue are of approximately equal value and each takes care of 15 per cent of the weight-bearing function.

5. If both cancellous layers are destroyed at the same time, the weight- bearing capacity is reduced by 30 per cent.

6. If the inferior compact layer and the inferior cancellous layer are eliminated or the superior cortical and trabecular system are removed, the weight-bearing capacity will be 50 per cent of normal.

7. The measurements sem to indicate that the trabecular tissue corresponds to a reinforcing system which helps to increase stability. It might be compared with cables in a bridge construction, the actual foundation of which is represented by the compact tissue.