Because of the presence of the femoral neck and the conversion of the femur into a hockey-stick shape, simple osteotomy of the upper end of the femur entails a number of complicated changes, which cannot be calculated by any simple table of relationships. To facilitate the calculations which are necessary in the performance of an upper femoral osteotomy, a mechanical model has been constructed.
The device here suggested provides a relatively easy method for determining, preoperatively, the exact site and angle of deviation for any abduction osteotomy of the femur. It permits the experimental study on a pelvic model of the effect of osteotomy in any given femur. It eliminates the necessity of cumbersome tables and immediately establishes the resultant of a number of variable factors to be considered in osteotomy. By appropriately adjusting the model to the measurements, as determined by roentgenograms, the postoperative result can be checked and adequate correction made before union has occurred at the site of osteotomy. The apparatus is simple to operate and both simple and inexpensive to construct.