In this presentation, I will be discussing how I perform a trochleoplasty and any considerations for trochleoplasty in kids. I will actually start with that portion of the discussion. At this point in time, there is one article in the literature from Nellitz et al in AJSM in 2018. It involved 18 patients who were skeletally immature and underwent trochleoplasty. They did not find growth or rest for any of those patients. However, it's important to note that they felt all of those patients were within two years of completing growth. So at this point in time, there is no literature support for performing trochleoplasty in very skeletally immature patients. It should also be noted that in trochlear dysplastics, the proximal aspect of the trochlea tends to be very close or overlaps the physis. And so the physis, specifically the anterior aspect of the distal femoral physis, is at risk for injury with trochleoplasty. So at this point in time, I am not performing that on skeletally immature kids. This video will demonstrate the technique. In this case, the patient has already undergone a medial arthrotomy with the patella subluxed laterally. In this particular patient, there was a concomitant tibial tubercle osteotomy also performed. However, in most patients, I do not perform a concomitant tibial tubercle osteotomy, and we can still get good exposure to the trochlea. To begin with, the first step once the trochlea is exposed is to incise the periosteum exactly at the lateral, medial, and superior edges of the trochlea. It should be noted that it is important to take the periosteum all the way down to the flexion point, which is decided based on the size and shape of the trochlea, and specifically the areas that are flat. We want to make sure that we get distal to the areas that are flat. Then a periosteal elevator is used to elevate the periosteum on all three sides of the trochlea. It should be noted that care must be taken particularly at the superior aspect because there are undulations underneath the periosteum that cannot be well visualized. Ideally, the periosteum is reflected in mass so that it then can be repaired later on. I use two or three K-wires to help retract the periosteum, and it is important to make sure that these are placed, generally speaking, between 1 and 2 centimeters away from the articular surface in order to have enough room to remove a portion of the cortical bone and not jeopardize either the hold of the K-wires or of the subsequent fixation later on. Obviously when placing the K-wires, one must be careful that you don't penetrate once you reach the posterior cortex. I usually do place the K-wire into or just gently through the posterior cortex. T-retractors in the medial and lateral gutters are also very helpful in terms of the exposure. Once the trochlea has been fully exposed, it should be noted that we do try to keep the cartilage moist throughout the procedure. We then turn our attention to removing a window of cortical bone on all three sides. Initially, a quarter or half inch osteotome is used to penetrate through the cortex immediately adjacent to the chondral edge, and to the degree that we can, we try to place the osteotome in such a way that it penetrates parallel to the subchondral bone or articular surface. Once the penetration has been carried out immediately adjacent to the trochlear surface, we then place another penetration through the cortical bone between five millimeters and a centimeter, either medial, lateral, or proximal. It tends to be that there is more bone removed proximal, and then it comes down into a wedge shape at the distal flexion point. All of that cortical bone is then removed with a ronger, and then we also use the ronger to remove as much cancellous bone immediately deep to the subchondral bone throughout the trochleoplasty exposure. Once we remove as much of the cancellous bone as possible with the ronjure we turn our attention to using this instrument which is a tip and side cutting bur. So we advance the bur in and then move side to side in order to help facilitate removal of the cancellous bone under the subchondral plate. Should be noted that this guide has the tip which is placed right on the articular surface so you know the depth of the drilling. This can be either five or three millimeters. It is important to make sure that the osteotomy deep to the subchondral bone is carried all the way to the flexion point distally and that at that flexion point it's carried all the way across medial to lateral. Depending upon the shape of the trochlea sometimes this needs to be approached both from the medial and lateral sides and then meet in the middle but it's important to make sure that the central and distal aspect is adequately burred out in order to help with the flexion of the trochlea. All of the reamings and the cortical bone are retrieved and maintained for packing underneath the subchondral bone once the fixation of the trochleoplasty has been carried out. In some cases the cancellous bone will still be prominent or have one small area that's prominent and therefore an osteotome is used to help shape that in order to adequately reduce the trochlea and have good contact across the entire exposed bone deep to the trochlea. You can see how that is reducing nicely. Once it is felt to be mobile enough then we set about fixing the trochleoplasty. An initial anchor is placed in the distal aspect of the trochlea just proximal to the notch. Three number one PDS sutures are used for a total of six strands. Three strands are maintained on each side and then brought to another anchor proximally. The placement of these anchors is evaluated and typically with this technique one is placed oblique and lateral and one is placed mostly central. You can see the one here placed central and now we'll be placing the oblique lateral. Note the tip there by moving the eyelet of the anchor all the way down to the first anchor It allows for the sutures to then lay flat. It removes any overlap of the sutures so that there is not an excessive pressure point in one small area but distributes the forces evenly across the suture. Once the implants are in place and the trochlea is adequately reduced, the wound is irrigated and then we set about filling the undersurface of the subchondral bone. Typically laterally will close down nicely but the medial side will still have some opening so this is packed with the reamings and the cancellous bone deep first working superficial and then the cortical bone that had been maintained is wedged in at the edge of the trochlea. Then free needles are used to take the sutures and pass them deep to the periosteum in order to pull the periosteum back to the edge of the trochlea. Typically the medial and lateral sides are not perfectly covered but they will fill back in with periosteum as well. You can see how the periosteum is nicely brought back to the trochlear edge. Closure and any other concomitant procedures are carried out and that is how I perform a trochleoplasty. Thank you.

trochleoplasty

surgical procedure

trochlear dysplasia

skeletally immature patients

subchondral bone