Here is a slide on my disclosures. I don't have any disclosures relevant to this talk So as a far as my approach to over and under resection, I think maybe a better title to this talk would have been Know the common bony resection mistakes and learn how to avoid them in order to get it right the first time but with that in mind and Knowing that we can't and I think can you guys look up at the screen? So knowing that we can't always get it right the first time I think that today I will try to talk about Why it's important to address the bone and femoral acetabular impingement we'll talk about the dangers of over and under resection in both the Acetabulum and on the femoral head neck junction, and then we'll talk about Some of the approaches that we have to address bony over and under resection of both the acetabulum in the femoral head neck junction Although I will be brief on that part because in all reality we don't have very many good options for that So what is it that we're trying to accomplish with bony resection? Well on the acetabular side, we are attempting to get rid of pincer impingement so pincer impingement with excess bone on the acetabulum causes abutment of the labrum against the femoral head neck junction and this causes Compression and then labral tearing the other diagnoses on the acetabular side that can be addressed our coxa Profunda or a deep acetabular socket that's defined typically by a lateral center at a jingle of greater than 40 degrees and Then the act of actually burying the acetabulum side Allows for a bony bleeding bed Which can help us when we're trying to get the labrum to heal back to that hip socket now on the femoral head neck junction side What we're trying to do here is get rid of the cam lesion so the cam lesion Causes impingement of the labrum tissue which results in labral tearing and adds additional stress to the chondral labral junction cartilage By resecting the cam we can actually normalize articular cartilage stress and can theoretically decrease the risk of progression to osteoarthritis We've seen that with greater reduction in cam height this results in improved functional outcome scores post-operatively and then conversely if There is inadequate camera section this results in lower outcome scores post-operatively in a recent study the authors showed that there was actually a six times higher return to sport odds if The post-operative alpha angle was less than or equal to 46 degrees compared to athletes with alpha angles above 46 degrees Another reason that we can't ignore the cam lesion is that we know severe arts Acetyl or cartilage damage and labral disease can be predicted by higher alpha angles So what happens if you resect too little bone on the acetabulum? Well, if you leave the hip with coxa profunda again defined as a lateral center of jangle greater than 40 degrees Patients will have less improvement than those with normal acetabular coverage, but in general with pincer resection Similar results are shown to those with normal acetabular coverage So basically if you leave too much acetabulum bone you do too little acetabular resection It's probably no big deal Now what if you resect too much bone off the acetabulum well resecting greater than four millimeters of acetabular rim increases contact pressures at the base of the acetabulum significantly and Unfortunately surgeons are not great at executing the plan degree of acetabular resection in this study the mean difference between planned and actual arc of acetabular resection was 19 degrees so off by quite a bit and If you respect too much acetabulum you can cause iatrogenic hip dysplasia and Unfortunately, we only have one solution for that and that is this surgery the peri-acetabular osteotomy so in the PAO we Cut the acetabulum completely free from the rest of the hip socket And then we rotate the acetabulum and fix it in place to restore any resected rim that should not have gone away Now what about on the cam side? What happens if you resect too little bone well under resection of the cam is the number one reason for a revision hip arthroscopy So we definitely want to address it And we've also found that alpha angles greater than 55 degrees after surgery are associated with lower hip joint survivability and less successful functional outcomes But what about too much bony resection off the cam? Well one of the big things to keep in mind is the blood supply to the femoral head and specifically the superior Retinacular arteries and terminal branches of the deep medial femoral circumflex artery which are the blood supply to the femoral head So if these are damaged this can result in a vascular necrosis requiring a subsequent hip replacement We also worry about femoral neck fracture this has been reported in up to about 2% of all femoral plasties and If the resection depth is greater than about 18 to 30 percent or If there are certain clinical risk factors including older age greater bone resection or increased femoral offset these can lead to a higher risk of femoral neck fracture, which as we know is also a catastrophic consequence Now over a section of more than 5% of the diameter of the femoral head predicts inferior clinical outcomes and higher rates of conversion to total hip replacement and One of the reasons that these outcomes may be less after over resection is the loss of the labral suction seal as seen here in deep flexion when the hip articulates with an area that has been over resected Now what do we do to treat cam over resection? Well, that's a really good question And we don't have a good answer for that there have been dermal allograft Descriptions to try to fill that gap Other allografts such as semitendinosus have been used to try to fill that graft or that defect as well Dr. Philippon has published two-year outcomes on 13 patients Showing that a remplisage of the iliotibial band can sometimes help fill that defect And so as far as my approach with acetabular resection I think we really have to be extremely conservative with the acetabular rim if you resect too much Acetabulum, we're going to give the patient dysplasia if you resect too little at acetabulum. It's probably not a problem We know that pincer in the native hip is protective of the acetabular cartilage So maybe it's better to leave that alone and remember that one millimeter of rim a section Results in about two degrees change in the center edge angle And this is only measuring the lateral most aspect of the acetabulum there might also be anterior or posterior undercoverage as well Now, what about the camera section? I think my approach is very similar to that described by dr. Aoki and dr. Salada basically making Outlining your camera section distal to where you think you need to take it so that you're not over resecting and then with the use of fluoroscopy bringing that Resection up smoothing things out very slowly because you can always take more bone, but you can never put it back So here's an example of a patient who presented To my clinic after having a hip arthroscopy elsewhere. You can see in addition to the capsular defect with the very clear Visible psoas tendon that this patient unfortunately had an intact labrum But very significant over resection of the cam and this is a difficult problem to solve So in summary bony resection is an important component of maximizing patient outcomes after hip arthroscopy And while we do know that cam impingement Residual impingement is the leading cause of revision hip arthroscopy I think we still need to tread very lightly and perhaps err on the side of under resection if The acetabulum is over resected that buys the patient a PAO and if the cam is over resected Well, we still don't have a good answer for how to solve that problem Thank you

bony resection

hip arthroscopy

pincer impingement

acetabulum

cam lesion