Thanks very much. I'm Ben Hayworth from Boston Children's Hospital. I'll be discussing PROs for Osteochondral Allograft Transplantation in the Skeletally Immature Knee. OCA is a technique of cartilage resurfacing utilizing transplanted cadaveric combined bone and cartilage grafts. First introduced in 1908, it's been in routine use in the U.S. for 30 to 40 years, with over 200 cartilage or osteochondral defect surgeries performed annually. Historical frozen grafts and preservation mediums have been replaced by fresh grafts due to studies showing long-term chondrocyte survivorship improvement. Ideal patients are young and active patients, including athletes, with studies suggesting improved return to sport if patients are under 25 with symptoms less than one year. Those with open growth plates are reasonable candidates as well as closed growth plates, though trochlear lesions may require adjustments to avoid effects on the physis anteriorly. Chondular lesions are more common than trochlear or patellar lesions, and large chondral defects or osteochondral defects associated with osteochondritis dissecans or OCD of the knee, as well as traumatic osteochondral fractures or occasionally focal osteonecrosis. Sizing tends to be greater than 20 by 10 millimeters. Other techniques can be used for lesions smaller than this, and contained or uncontained lesions, which tend to have poor results with Oates and Macy, are candidate lesions. These tend to be failed prior cartilage resurfacing techniques, failed prior OCD fixation, or potentially unsalvageable or unfixable primary OCD lesions. It's ideal for osteochondritis dissecans and the most common indication in adolescent patients due to not requiring size constraints, having relatively quicker recovery or rehab, and being a structural solution addressing underlying bone and cartilage problems. Some literature suggests shallower plugs are better, but one must replace the full thickness of the abnormal subchondral bone with an OCD, so deeper plugs between 7 and 10 millimeters do quite well. Disadvantages, there's some question of the long-term results with a fairly minimal research into this area, and bone healing by a creeping substitution allows the host bone to replace the donor bone. It's a question of the viability of the chondrocytes due to transplantation as well as impaction forces, and this requires time and a matching process with grafts lasting up to 28 days. It's a question of cost and insurance coverage in some systems, and is technically demanding with a learning curve, and some studies suggesting a reoperation rate up to 30 percent, with longer-term studies at six to eight years suggesting failure rate of around 10 percent. Who shouldn't get an OCA? Contraindications may include obese patients greater than 35 BMI, those with instability or concomitant ligament injuries, those staged or combined procedures can be performed. Severe or uncorrectable malalignment, though for correctable malalignment, staged or combined procedures such as hemipitheoidesis or guided growth for the skeletally immature and osteotomy for the skeletally mature should be performed. Other patients potentially doing poorly are those with risk factors for poor bony healing, such as smokers, those on corticosteroids or diabetes, severe or diffuse AVN, those with metabolic bone disorders, and those with severe joint disorders such as diffuse OA or inflammatory arthritis. Here is a case of correction with an osteotomy that did well. This is in the realm of correctable malalignment. Some illustrative cases, here's a 17-year-old male baseball player with bilateral lateral femoral condyle OCDs with a pre-op MRI showing global central collapse of the subchondral bone following drilling and fixation procedure approximately a year prior, so failed healing. In terms of donor site preparation, you can see the Z retractors with this lateral peripatellar arthrotomy to provide optimal exposure and place a perpendicular guide wire with use of a cannulated reamer to prepare the bone bed. Graft preparation includes a proprietary workstation with a corresponding sizer to the reamer and then graft extraction with use of a saw and optimization of the graft, which generally includes lavage to remove host bone factors. Here's a graft appearance post-extraction. You can see an arrow showing the transverse saw cut to remove the graft. Graft placement or impaction should leave a flush articular surface by palpation at all points in the graft as seen here. Here's a post-op CT at six months showing deep bony healing. With a patient ready for impact forces. A second case of a 15-year-old male soccer player in medial femoral condyle OCD that had previously undergone drilling two years with pain. An MRI revealed an involuted center of a large lesion with macerated cartilage. Ideal given the size for a subchondral allograft with donor site preparation. Here are arrows showing that macerated cartilage. And the perpendicularly placed guide wire allowing for the reamer to have optimal exposure to avoid trauma to the patella or the meniscus. And then measurements of the deep portion of the graft are performed at four points so that the corresponding graft prep allows for the same heights at those four points. And then ronjuring of the sharp bony edges of the deep portion of the graft allows for smooth initial insertion and start of the impaction. A post-op CT at six months shows a slight imperfection of the perpendicularity of the graft despite a good clinical result which underscores the importance of this portion of the procedure both at the time of reaming as well as the time of graft preparation. Third case of a 16-year-old male lacrosse player with lateral femoral condyle OCD. Underwent OCD drilling and fixation with many implants and deep curettage and bone grafting. This failed and the patient underwent a MACI. With failure of the MACI due to poor incorporation of the morselized bone graft which is part of the MACI sandwich technique showing that larger lesions with deep involvement of bone may not be ideal for MACI with arrows showing gross failure of the graft due to failed incorporation of the bone graft. This underwent osteochondral allograft as a salvage technique though one can see this is partially uncontained so two headless compression screw screws were placed for fixation as backup for the press fit technique. This showed good stability and good healing with a future second look arthroscopy showing good maintenance of the margins of the lesion. There's expanding technology in osteochondral allograft with new options arriving each year such as off-the-shelf pre-cut plugs in various sizes and oval-shaped unicondylar grafts or plugs, rehabilitation calls for touchdown weight bearing for the first six weeks with early range of motion from week 6 to 12 weight bearing is initiated with stationary bike and early strengthening from months 3 to 6 advanced strengthening and a CT scan is favored by some to assess the deep bony healing at four and a half or six months post-op if there's advanced healing progression to impact strengthening running and agilities with return to sport between six and nine months. Thanks very much.

Osteochondral Allograft Transplantation

Skeletally Immature Knee

cadaveric combined bone and cartilage grafts

osteochondritis dissecans

graft viability issues