 So there are various techniques for dorsal decompression and fixation. So it was just that one of the great players in spine surgery, at least in Germany, harms. He is really one of the earliest fixation experts. He already stated in the 80s that with the standard methods, the ALIF and the P-LIF, there are some disadvantages. With the ALIF everybody knows it. They have potential vessel injury. It may be a two-stage surgery in May. There may be some other problems in the P-LIF. Perhaps maybe a one-stage surgery. But to bring in the cages, you have to retract the dura with some, perhaps, disadvantages. And he was thinking, well, what to do better? And this is a comparison of how the techniques work. This is the P-LIF, you know, very good. You can make it from both sides after a good decompression and bring in small cages bilaterally. But his idea was to prevent mobilization of the dura, to prevent tearing of the dura. And he developed this approach, which is after removal of the joint, you have quite nice access in the axilla of the nerve root and the dura that you don't need any mobilization of the nerve root or the neural structures. This is the P-LIF, you know, very well. And this is the cage, which is a kind of banana-shaped cage, which is brought in a bit around the corner. What you do, you make a standard pedicle screw placement. There's no difference in it. And you may already make a rod on one side because it's the one-sided approach to make a slight distraction that might help in the surgery later. So we don't have an O-arm. It's not very popular in Germany because it's quite expensive and takes a lot of space. We have this 3D C-arm, which can provide not exactly a CT scan quality, but it's quite good. We're working with this system about 10 years and it's adopted to the metronic software. The skin incision depends on the work what you want to do. You need a spine clamp and a neural navigation. And it's just about pedicle screw placement. It's always about experience. So when I do something like this, I'm happy about the navigation, but I'm sure you do it without. It's always a matter of patient safety and your personal experience. So I like to use navigation for that. And it saves in general O-R time. And it saves in our hands a lot of radiation times because spine surgery is very intensive in the exposition of X-ray. So what you do after the placement of the pedicle screws, you may bring in a rod or not. It depends on your beginning. It takes too much space, but it may be possible. And you resect first the inferior, then the superior part of the joint. And after you've done that, you have exposed already the nerve root and the disc. If there's a stenosis of the spinal canal, then of course you can do just a decompression to both sides in that fashion I showed it to you. But there are people who just have a slight instability without major decompression and then this exposure is good enough to remove the disc. You can make a disc removal. You have to remove the end plates with curates with different angled forceps. These are these kind of curates. So I think you get it from any company. It's just from their manual. And after you remove the end plates, you make a bit of distraction to bring in the cage. In general, we use some graft from the iliac crest because especially later the ventral ossification is very important. And after you have brought in the spongiosa, then you can bring in the cage. And you can do it either with a rod instrumentation and distraction or you can use this instrument and you bring in this cage, which should perfectly sit. And after you brought in this cage, which is in the middle or posterior part, ideally, then you put in some distraction so that you re-establish the lodosis and there's a good fitting of the cage. And you can, of course, use some additional spongiosa. It's up to you. And you can do this telive with decompression, without decompression. You can make a laminatec to me. You can do a selective intrac decompression. And there are even minimal invasive variations of that. I think in new surgery in India there had been a major publication a couple of years ago where they did a mini telive or minimal invasive where you make a percutaneous implantation of the screws and where you can make, with a mini incision, the selective intrac decompression. Or there are also these X-LIF variations where you make it extremely lateral. There are several variations of that. And the advantages are... Anatomy is you're used to it. And if you don't have to make a laminatec to me, you can do it on one side. It's really have a shorter OR time, less exposure of all the bone in the neural structures. It's quite good. The only thing is if you're not used to it or if you are too reluctant, there may be some disadvantages for fusion. That means perhaps you make from one side incomplete disc removal. And if you have a bilateral symptomatic, for example, use the noses of the pheramen, it may be in a quad for the decompression. But we did it now over, I would say, eight, nine years and we are quite happy. So the only thing is, of course, there are contraindications, bilateral pain. If it's only minor disc generation or if there's a cathodic changes in the axis. So you can't do this minimal or less invasive procedure. You have to do a vertebral removal or a cage or stuff like that. But we make quite good experience with that. And we use it always a lot for the decided if it has to be operated. And even you can do a telivariation in the thoracic spine where you may sacrifice a nerve root, which is possible. And especially an elderly patient who are not suitable for an anterior approach, you can really sacrifice one or two disc roots and make a vertebral disc replacement or you can make an expanded cage from the dorsal lateral approach. This is possible. This kind of technique is always the same. Thank you.