It is difficult for me to spell out the success rate (in numbers) for valgus intertrochanteric osteotomy. This is because the variables are more than just the valgus osteotomy vs cancellous screw fixation. The results in a given case of intra-capsular fracture neck femur depends on:
1. Ggeometry of fracture line; more horizontal the fracture line better the union rate.
2. Degree of displacement of fracture; greater the displacement of fracture greater the possibility of it going into a delayed union.
3. Time of surgery; delay in surgery causes possible damage to blood supply.
4. The blood supply of the femoral head; this occurs to a varying extent from 11 to 19%.
5. More than one of the above factors may be operational in a case.
Having said all the above, it is a good operation to do, as it changes the fracture line to a more horizontal configuration and it results in a better union rate. However, the procedure simple cancellous screw, does not do any such modification and it can be done only in a fresh case. Valgus osteotomy on the other hand can be done in fresh and old cases. The catch is valgus osteotomy is some what more technically demanding than cancellous screw fixation.