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VID1-00640-EN | A | Trochleoplasty - Indications and Methods

Philip Schöttle

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Trochleoplasty - Indications and Methods

I want to introduce and explain to you a little bit about trochlear dysplasia. The combination with patellofemoral instability and the treatment by trochlear plasty. I think the biggest question is when do we really have to perform a trochlear plasty? And when is it enough to stabilize the patella by an mpfl? Only if you focus that, then the apprehension sign and the j sign is, for me, the most important examination to decide if I have to go to perform a plasty or not. If, for example, you see this little girl who has a positive J sign at 40 degrees of flexion, when all of a sudden the patella pops out to lateral, then I see the MRI with a missing groove and there is a convex trochlea. And in the moment the normally shaped patella. Tesla. Has no engagement and no guidance anymore and is flying out to natural. The indication for a trochlea plasty is given. Why? If I only would do an mpfl, then eventually I could keep the patella in a centralized place, but I would increase the pressure onto the convex trochlea with a patellar edge, and that would be like bringing two convex things onto each other. First of all, the pressure increases and second of all, it could not stay stable anymore. So and at that point, I see the indication clearly given. I'm often asked about early degeneration. Or try this after performing a trochlear plasty and the question about the cartilage viability. And since 2002, when I perform this trochlear plasty in the technique more or less the same as you see today, I have not seen any drastic changes into degeneration. Iteration. So we had to replace on the other side. I've seen a lot of patients in the late 20s and early 30s who should have had a trochlear plasty in the age of 1820. They have been treated with a transfer of the tuberosity or a lateral lengthening, and they're ending up in such an early degeneration that in rather those patients I then have to treat with a partial replacement in patients with a dysplastic trochlea you have to imagine this is like playing bowling on a convex bowling lane. And when you throw the bowling ball, it cannot hit any pin. Why? Because it will fall to the right or to the left, and a transfer of the tuberosity will not be the solution, at least not as an isolated procedure, because this is only changing the starting point, and it makes no difference. Coming back to the example with a bowling lane if you throw from here or from there because the lane stays convex and the ball will fall off. As an additional procedure for getting the starting point more centralized. After creating a groove, it may be, and sometimes it has to be a very helpful additional procedure. With these five millimeters distance reamer, I can detach the cartilage from the underlying bone so easily. The next step is thinning the cartilage flap from the underlying bone to make it more malleable. You also can add a three millimeters distance guide, and then you can thin out the bone behind the cartilage flap. So in the end, it's really easy to mold it in the closing of the lateral retinaculum, which I recommend to open in a z-plasty to eventually gain some soft tissue. Distance should be performed in 70 degrees of flexion, because in 70 degrees of flexion the tension of the lateral retinaculum is the highest in the whole range of motion of the knee. Once this is performed in all trochlear plastics, I recommend to perform an additional mpfl reconstruction. The reason, therefore, is that the trochlear plasty is influencing the patella from ten degrees in flexion onwards, but close to extension. Even a normal trochlea has no stability function without a working mpfl, which is in all cases gone after the first patellofemoral dislocation. So don't be afraid performing this procedure. It is not like a last point or a last decision procedure. It's something you also can offer as a first time procedure. And with these new reamers, it's such a safe and reproducible intervention.

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