Arthroplasty – Anterior vs. Posterior Hip Replacement

Transcript

Today we’re gonna go through the differences in specifics between anterior and posterior hip replacement surgery, and go through exactly what we do to perform these different procedures. First of all, anterior just means the front of the body, versus posterior means the back of the body. And so that’s where we put our incisions. So in an anterior approach, our incision is located more in the front of the thigh versus a posterior approach, which is more in the buttocks area as shown here in this diagram. So from a posterior approach, the incision is made over the gluteus maximus muscles, which are spread out. Then you reveal the external rotation muscles overlying the poster hip capsule, and these muscles have to be taken down to reveal the hip in order to perform the hip replacement from a posterior approach. These muscles are then repaired back to the hip, but often will just scar in from an anterior approach. We avoid all of the muscle cutting by going in between the interval between these two muscles here. The front muscle on the front is called the rectus. It’s part of the quadriceps mechanism. And over here, it’s called the TFL or the tensor fascia lata muscle. We go in between these two muscles, spreading open those muscles, and revealing the hip underneath from an anterior approach. We avoid all the muscles in the back by going in between the interval between the rectus and TFL muscles. The rectus is part of the quadriceps mechanism and the TFL is this confluence of muscles on the side of your hip. We go in between that interval there, spreading open the muscles with my retractors allowing us to identify the hip and the hip capsule just underneath these muscles. We perform the whole hip replacement through this interval.

And then simply when we’re done, we let go, allowing the muscles to return back to their native state. Once we get down to the hip, it’s a hip replacement, regardless of whether we come in from an anterior or posterior approach. Essentially, what that means is that we make a cut in the middle of the femoral neck in order to take out the entire diseased ball that’s inside your hip. That allows us to expose the pelvis on the other side of your hip. The first thing we do is we take these circular cheese graters, we call them reamers, that take out all the arthritis that’s inside the pelvis. The pelvis is then shaped to accept the acetabular component. This is a model, but the real one’s made of titanium. It has small little holes in that acetabular component, which allow your bone to grow into this implant over time, that implant is fit with a scratch fit inside the pelvis and is grown in in time.

It typically takes about three months for this in-growth process to occur. Inside this cup is a polyethylene or a plastic component that’s specifically engineered to withstand wearing out over time. Then we’re able to focus on the femoral component. We make a trough down the middle of the femoral to accept this femoral component. This is also a model, but the real one’s made of titanium as well. It also has this small ingrowth surface, which allows the bone to grow into this component as well. It’s a nice snug fit after we’re all finished, and completely secure. Then we put a ceramic ball on top and we put you back together. This bearing surface, or the parts that are moving are, is a ceramic on plastic bearing. We perform the entire surgery using x-ray guidance, which helps to ensure that the components are placed in exactly the precise way that I want them to. In addition to evaluation to the other leg, to make sure we have the same lengths compared with the contralateral side.