I first want to thank Isha for the opportunity to join this webinar and present the Colorado University PAO technique. Conceptually, the COPO is a treatment strategy rather than a paired gastrootomy technique alone. It is based on a holistic approach to the heat, which includes pre-arthroscopic treatment of intrategular pathology and impingement, followed then by minimally invasive to incision interlocking gastrootomy, which enables immediate weight-bearing and rapid recovery. We all see and appreciate the natural history of dysplasia if not treated, whether macro or micro, clinical instability is a one-way ticket pathology. But let's go back and quickly review some of the basics that were presented here before. A stable retroversion can present in many shapes and forms. We can see it with folks that have deep, overly-covered socket, but also with shallow, unstable ones. The key factor to appreciate is that version is a relative value. We can have anti-verted deep or stable loom, same way we may see shallow socket that is retroverted. It is all about the relationship between the anterior and the posterior walls. But before we determine if a hip is anti- or retroverted, we must make sure that the x-ray was taken appropriately without pelvic rotation or tilt, and preferably with a patient weight-bearing. Change in tilt, as seen here, can change the way that stable loom will present itself to us, eliminating signs like crossover or ischial spine. We also want to make sure that we measure the LCE appropriately, accounting for the true weight-bearing that stable loom is defined by OGATA. Other indirect signs, such as labral size or cartilage thickness, can also assist in appreciating instability versus other functional abnormalities as the possible source of pain for the patient. But if we go back to retroversion and dysplasia, we can see that it's not an uncommon phenomenon. The key again is to appreciate that the presence of retroversion and dysplasia is not due to too much anterior coverage, but due to not enough posterior coverage, altering the normal relationship between the two. Trimming the rim in these cases will just exacerbate the instability. The reason that the reverse is in parentheses here is because most of these cases also lack lateral coverage, while the need to correct only anterior coverage without adding more lateral one is not that common. So how do we know if a patient can do well with a scope-only strategy? We first have to look at the before-surgery parameters, the bony architecture of the femoral index of the loom, the gender of the patient, the level of laxity, previous surgery's outcome, the labral size and the cartilage thickness and damage pattern on MRI, range of motion characteristics, and obviously impingement. During the surgery itself, during the scope, we want to look at the ease of destruction, the type of cartilage flat that we encounter, labral size and tear pattern, and the ligament and tear status. The main parameter to consider after surgery is if it didn't work. So we learn as a community when it doesn't work, and started in the past few years to shy away from trying to fix everything through the lens of the arthroscope. With that in mind, which cases would prompt clear bony correction strategy? The three main ones are deficient lateral or anterolateral coverage and congruency, excessive version, and excessive torsion. The lateral coverage is an easy one. We have MPL-validated parameters that jump out of the X-ray for that one. Antero coverage, however, especially when the lateral center edge angles seem within normal range, requires more attention to details. However, the CT can help us here with more precise angles and better representation of deficient antero coverage. You can see the normal and the abnormal one. Back in the X-ray now, we can actually appreciate retro and antiversion even without a CAT scan using the neck axis distance. This would then correspond with what we see inside the hip during arthroscopy with deficient antero horn of the socket. Now you can see all three together. Posterior coverage can also be assessed on X-ray the same way, and this will correspond with the 3D images on CT or axial CATs. The next piece in the puzzle would be the shape of the extabular roof. A flat or upslope sore seal can also direct us towards a true pathology. Those would represent instability signs. Next step would be to review the other side of the equation, the femoral anatomy. Torsion is the position of the femoral neck in relation to the femoral condyles, different than diversion being the position in relation to the pelvis itself, which changes obviously in IR or ER of the hip. Retro-antetorsion of the femur have significant effects on how the joint would function and can be protective from or amplify instability or impingement characteristics. Bedside patient's range of motion can tell us a lot about this parameter, and assist during PAO surgery on range of motion assessment is a key. We also showed that the effect of torsion outweighed the effect of CAM impingement on internal rotation. And the CAM lesion in these cases doesn't even come into play. So PAO is a combined stage procedure. First, the arthroscopy, which treats pain sources within the joint, FAI and intra-articular pathology. Thereafter, would come the PAO or the DFO or combined, treats the bone-immune alignment. During the scope, we want to be reassured that the patient is heading in the right direction. Every finding should be expected or explained. Ease of distraction or the size of the labrum are important factors to look at. During arthroscopy, we also have to respect the dynamic stabilizer and maintain a small capsulotomy, which will be repaired at the conclusion of the surgery. The inside-out technique was developed specifically for unstable patients, when no re-impriming is required. Label repair technique in dysplastic patients should avoid rim trimming, as there is no pincer to resect. This will reduce the rates of capsule label adhesions and yield better vector of pull for improved suction seal. This technique can also be used with multiple anchors. Some dysplastic patients have an inverted labrum with large gap between the labrum and the femoral head when off traction, suggesting no functional suction seal. This can actually be seen well on MRI as a blunted tissue lacking the common triangular shape. It is correlated with the upsloping sore seal and can be corrected with labral advancement technique using an inside-out labral repair technique. But we first must check it off traction in every single case. In cases of deficient labrum, reconstruction may be indicated. Appreciation of cartilage damage is also a key in these cases, differentiating between inside-out and outside-in pathomechanisms. If we're in for a simple FAI surgery and encounter an inside-out instability type flap, we should start looking for reasons. Whether there was an anteversion that we overlooked, excessive torsion, hyperlaxity. Cartilage flaps are debrided and microfracture performed to set the patient for optimal cartilage healing part of the PAO. It's seen here during second look for scar tissue removal. At times, cartilage autograft is also required. Many patients with hip dysplasia present with large subchondral cystic changes. These are decompressed and grafted with bone patty. Finally, CAM impingement, which is very common in dysplastic patients, is reduced, taking into consideration future improved coverage, femoral torsion, and preoperative range of motion. So now we're ready for the next stage, the PAO. So what are the goals of the PAO surgery? On the patient's end, obviously reduce pain, improve function, prevent or postpone total hip replacement, reasonable recovery with regards to pain and disability, minimal complications hopefully, early return to life and sports. On the surgeon's end, or how do we reduce the stress here? Reasonable learning curve, safe, reproducible, low complication rate, reduce admission time, reduce surgical time, and obviously good outcome. Well, the COPO is based on the GANS and the BIPO. The GANS and the BIPO are the two most common techniques currently utilized worldwide. The GANS or the Bernese is by far the most popular one globally. The COPO is a method combining the best of both of these worlds in a minimally invasive package. Nine out of 10 patients are young females, obviously, in dysplasia. So concealed incision and aesthetics are a major consideration. Here are the osteotomy lines of both the GANS in red and the COPO in yellow and blue. The blue line is the part of the osteotomy, which is cut via the posterior incision, the COPO. The yellow line is the anterior incision osteotomy. On the top left, you can see the sciatic nerve on top of the short external rotators. The rotators are then split, not cut, exposing the subcutaneoid fossa. The sciatic nerve is protected and the ischium is cut using a precision saw, and the curved osteotome then is used to extend the cut quite proximally. Seeing, protecting the sciatic nerve during the ischial cut is a key factor. The angle of the cut is wide and smooth, enabling easier manipulation once fragment is free. This is especially important in retroversion cases because it is generally easier to move the fragment into retroversion than to antibody it. The patient is then rolled to the supine position without changing the grapes, and the pubic ramus is cut just media to the tudor plane to get good surface. Connecting the osteotomy line is relatively fast and simple because there is very short portion of the bone left to be cut, and this portion is far away from the nerve. Using external fixator, the correction is achieved and fixed. The osteotomy also generates favorable bone-ear position for rapid weight-bearing and healing. Also, there is no need to detach the rectus or cut the AIS during the PAO as it is not usually a step during the Bernese as seen here. I found out that many folks, especially athletes, don't like the associated reduction in flexion or pinch after the PAO moves the AIS forward, and I now regularly shave the piece of bone and reattach the rectus femoris. These are different examples of patients treated with the CUPAO from high-level athletes to unique cases from extreme dysplasia to very fine correction after failed scope strategy. Some would require fixation of an os and valgus of various producing osteotomies, while some cases would require the rotational osteotomy just to maintain physiological range of motion. So you can see here one year after bilateral scope and PAO, this is one of the top climbers in the world, 13 weeks after one side scope, just days before she did the other side. In the past five and a half years, I've done close to 400 CUPAOs, and the demographic of the first 200 cases can be seen here in this JBJS paper. You can see here the demographics, obviously the majority of the patients are female with long duration of symptoms, and a quarter of the cohort had broken genital lines. Concomitant DFO was performed in about 10% of the cohort for both successive ante or retroversion of the femur. The pre-surgery lateral center edge angle was about 18 degrees and improved to 32 post-PAO. Only 6% of the patients required transfusion, in addition to blood returned to them via the cell saver. Average bleeding improved, by the way, over time as the technique was refined, and now it averages about 400 CC per case. Nanodegenerative hip scores kept on improving over the first two years to reach a score that tops the results reported for soft tissue procedures for borderline dysplasia patients by all studies. Thank you.

COPO

hip dysplasia

PAO surgery

surgical technique

successful cases