11 Oct Stature Lengthening : which nail, where and why?
We get a lot of questions with regards to which intramedullary lengthening nail and technique we use. Patients are often worried about the potential complication of getting a bony deformity when undergoing this surgery. At CLLC, we make sure that doesn’t happen.
Most people doing stature lengthening in north America are using the PRECICE 2.2 nail, which is made of titanium and communicates with a magnetic external remote control (ERC) to do the lengthening. What people don’t know, is that there are two different types of PRECICE nails, one called piriformis and one called trochanteric. The difference is where the insertion point is on for the nail in the proximal femur.
PIRIFORMIS ENTRY
TROCH ENTRY
The piriformis nail is a straight nail and so when lengthening down the femur bone, there is no deformity created. However, the femur bone is not perfectly perpendicular to the ground. It’s actually about 7 degrees (purple line) into valgus from the mechanical axis of your leg (blue line). That means that when you lengthen 8cm, you will be pushing the femur leg into a little bit more of that valgus (purple line). This is a completely acceptable and common way of doing stature lengthening and many surgeons do it this way and don’t feel that these few degrees make a big difference.
At the CLLC, we like to use the PRECICE trochanteric entry nail. This nail is 5 degrees bent at the entry point, for a few reasons.
- We want the leg to stay straight during the 8cm lengthening
- The trochanteric entry point can make patients recovery a lot easier and surgery less painful.
- The most important part of making sure that we don’t create deformity as we lengthen is where we place the bone cut (we will discuss this in a future blog).
The troch entry nail pushes the bone into very slight varus (2-3 degrees) at the location of the bone break so that as we lengthen, we don’t create valgus deformity. If you use a troch entry nail at the correct trochanteric entry location, there is no reason to worry about deformity.
IT is never indicated to use a piriformis nail at the trochanteric entry point, that’s how you can cause deformity.
Finally, we also want to be sure that we don’t change a patient’s natural rotation of their leg during this process. To be sure we maintain patient’s normal rotation, we use an external fixator during surgery. The external fixator is removed before the patient wakes up.
If you followed all that great! Hope that helped clarify some points on which nail, where and why!
