Hi, my name is Cliff Willeman from Children's Healthcare of Atlanta. I'd like to discuss microfracture and OCD. Is this really an option? These are my disclosures. A bit about OCDs, they're most common in the males than females and occur in the adolescent age ranges of 10 to 15 years. The most common location in the knee is along the post-total lateral aspect of the medial femoral condyle. And again, stability guides treatment of these lesions. The Rock Group has devised a useful strategy using descriptors of these lesions to help guide the treatment. OCD treatment revolves around the lesion size with those being less than 2 to 3 square centimeters as proposed to being candidates for debridement and mirror stimulation or microfracture. Microfractures are typically used to describe those lesions in which there are full-thickness chondral defects and the subchondral plate is intact. Again, the treatment of these lesions and the cartilage of the knee revolves around the defect size with mild lesion sizes treated with mirror stimulation techniques more commonly and the larger lesions, more than 2 square centimeters, being treated with cartilage restoration techniques such as autologous chondrocyte implantation, now called Macy in the second generation, or fresh osteochondral allograft transplantation. Microfracture has been shown to benefit those lesions which are 2 square centimeters or smaller where the shoulders of the subchondral bone well support the microfracture site and this minimizes the symptoms from subchondral bone stimulation and overload. These lesions have shown the lowest likelihood of progression, but the problem is OCD lesions are rarely smaller than 2 centimeters squared. A bit about the basics of microfracture. It's a first-line treatment for small, full-thickness chondral defects. It's certainly attractive because it's minimally invasive. It's technically easy and it's of low cost. The principles are that we debride the chondral flaps down to the calcified cartilage layer. We remove the calcified cartilage layer. We want to have stable borders so the borders are vertical and there's no remaining delaminated cartilage. We then use an awl to place holes in the subchondral plate in a perpendicular orientation, 2 to 4 millimeters apart. This allows a clot to form containing mesenchymal stem cells to stimulate fibrocartilage formation. Again, fibrocartilage is largely type 1 cartilage and overall has shown inferior stiffness and wear characteristics compared to hyaline cartilage. Schematic showing the debridement and microfracture technique. So a curette is used to remove the chondral edges that are unstable until we have a vertical stable borders. Next, the calcified cartilage layer is removed and then an awl is used to place the subchondral puncture lesions. This allows a mesenchymal clot to form, allowing for differentiation into fibrocartilage. So again, microfracture in OCD is technically simple with good early results in small contained lesions, but in large lesions, the fibrocartilage really lacks integrity of the hyaline cartilage and shows inferior outcomes with deterioration over time and earlier radiographic changes consistent with osteoarthritis, again, leaving this with a limited application for the typical large lesion size of OCDs, which are larger than 2 square centimeters with associated bone loss. In 2009, though, earlier in the evolution of treatment of OCD, a prospective randomized study comparing osteochondral autologous transplants to microfracture was performed. This report on 47 patients less than 18 years of age. Again, the mean defect size was 3.2 square centimeters with a mean fall of 4.2 years. Both groups showed good early results, but at final follow-ups, the good to excellent results were present in 83% of the OATS patients, but only 63% of the microfracture patients. When we looked at achieving pre-injury athletic level at 4 years, again, 81% of the OATS patients achieved this versus only 14% of the microfracture. Then lastly, when you look at treatment failures, there was a 41% of the microfracture patients failed treatment versus none of the OATS patients. With any operation, it's useful to think about the potential for revision and the effect of the current operation may have on that. Tom Midas published using their extensive series of ACI patients with 522 defects and 321 patients. In the patients that had prior mirror stimulation versus those that different, there was a significant difference in failure rate in patients that subsequently had ACI. So 26% of the patients in the mirror stimulation group, those that had mirror stimulation before ACI had a failure versus 8% in the controls, controls being those that did not have prior mirror stimulation before ACI. So what are potential applications of microfracture in the treatment OCD? Well, it's a small narrow window. So those unstable small lesions with a shallow bony component, less than two centimeters square, I think more commonly may be useful in the partially healed OCD that has a small remaining unstable defect size. So you had a large lesion, maybe initially treated and there's healing and then at follow up, there's a small remaining unhealed chondral defect. You can see this after drilling as well. And so it's more common though, to consider techniques that restore both bone and cartilage loss for large lesions. In the salvageable case, it would consist of OCD repair. So debridement of the OCD bone bed with bone grafting and then refixation versus the unsalvageable large lesions in which osteochondral allograft transplantation or matrix autologous chondrocyte implantation with bone grafting are all great options to consider. Thank you very much.

microfracture

osteochondritis dissecans

knee injuries

fibrocartilage formation

cartilage restoration