Sometimes it’s necessary to remove part of the femur (thigh bone) during a total hip replacement. This procedure is called a trochanteric osteotomy. It allows the surgeon better access to the hip joint. The piece of bone that is removed will be wired back in place.
In this article, orthopedic surgeons review the various wiring methods used to reattach the bone. Advantages and disadvantages of each one are discussed. Recommendations are made for the type of wire and knots to use for the best results.
There are three fixation systems used to reattach the trochanter to the femur. These include wires, cables, and cable grip systems. Each type of device is discussed in detail. The results of studies using each method are summarized.
The wire or cable must be able to keep the bone fragment in place until union takes place. At the same time, it must hold up under compressive, shear, and load forces.
For example, muscles that move the hip apply more than four times the patient’s body weight on the hip. This type of force occurs anytime a person goes up stairs or gets up out of a chair. Even with fixation, muscle contraction be strong enough to pull the bone segment away from the femur.
The authors suggest using 16-gauge wire with a square knot or knot twist. This provides the best strength for fixation to hold the bone in place and prevent migration. At the same time, this wiring method has a lower rate of breakage.
Nonunion is most often the result of limited experience of the surgeon and technical errors. Placement and tightening of the wire are key factors. To prevent breakage of the fixation device, surgeons give patients special instructions to follow. Certain movements such as active hip abduction (moving the leg away from the body) must be avoided.
Finally, patient selection is important to the success of the operation. Previous hip surgery and the presence of other hip or spine conditions are risk factors for a poor outcome. The surgeon must always choose the patient and the choice of fixation device carefully.