This is the smaller lesion debate of microfracture versus autograft transfer. I'm Dr. Clay Nully from the University of Missouri. My disclosures are listed on the Academy website. As everyone knows, cartilage injuries are highly prevalent as there are over 2.5 million knee arthroscopy performed each year in the United States alone with around 450,000 focal cartilage defects identified. Cartilage injuries do not heal very well spontaneously due to a limited blood supply and the fact that the cells cannot migrate out of the zone of injury or out of the zone of repair very well. So, the treatment algorithms are often complex and frequently changing as new technology evolves. In addition, not every cartilage patient and not every cartilage lesion is the same. There are lesion-specific differences in size, whether it's solitary versus multifocal, whether there's not associated pathologies such as early osteoarthritis or inflammatory arthritis is present. There's different locations, whether it be on the tibial femoral side or the patellofemoral joint or a mixed pathology, and then there's the variations in subchondral involvement and whether or not there's subchondral edema or cystic lesions present or previous marrow stimulation procedure or previous procedures performed on the knee joint itself. And all of these things can influence the natural history and the way that we treat each of these lesions. There are a number of different educational instructional course lectures and manuscripts published on evaluation and different techniques in each way that we treat cartilage based on the location and pathology, in particular, this one in JBJS by Dr. Cole and colleagues is an excellent discussion of surgical management of articular cartilage defects in the knee. As always, we're discussing cartilage pathology, even small lesions. It's important to address concurrent procedures and pathology that may exist, including any sort of limb malalignment, which may require osteotomy, meniscus deficiency, which may require meniscus transplant, and ligamentous instability, which may require various forms of repair or reconstruction. In addition, cartilage procedures typically require various strict types of rehabilitation protocols, which may include non-weight bearing for a period of time for condylar defects. Weight bearing is tolerated, but locked in a brace for patellofemoral defects and various levels of range of motion. It's important to understand all the surgical options and to think ahead to the next surgery if necessary, and if there's another surgery potentially needed, and very important as always to manage expectations and counsel patients accordingly. There are many different things in the, quote unquote, cartilage armamentarium that we want to have available to us, but in this particular talk, we'll be talking about microfracture or marrow stimulation and autologous osteochondral transfer. Microfracture or marrow stimulation has been around for a prolonged period of time. The benefits of microfracture include it being technically easy and can be done all arthroscopically in a single stage procedure. It has good short-term outcomes in a number of studies and is adequate in low-demand patients. The limitations include that it sometimes has a complex rehab with restrictions in weight bearing in the early post-operative period and restrictions in return to play. There's multiple studies that have shown functional decline after 24 months. The procedure itself forms a fibrocartilage as opposed to true hyaline cartilage, and it may result in a bony overgrowth in the area, depending on the severity of the microfracture. If you're going to perform some form of marrow stimulation technique for these small lesions, the technique itself is important. Historically, we used to use large chondral picks and be very heavy-handed, hitting very hard, which would damage the subchondral plate and the subchondral bone. Studies have shown that that's not very good and that that actually can result in damage to the subchondral bone and significant subchondral edema and can create issues long-term. So it's important to use small tunnels and what has even been termed nanofracture with very small K-wires or very small drill bits or very small devices that have been developed to create small channels for the marrow stimulation and try and utilize minimal or no heat. So again, minimal drilling, thus minimizing the damage to the subchondral bone. It's important to know as well that if you do perform a microfracture or marrow stimulation, you have to be very careful with the lesion itself, as many studies have shown that the results of osteochondral oligraft transfer and autologous chondrocyte implantation after a microfracture, if those are needed, are much worse. The outcomes are much worse. And so you just need to know the backup plan if the marrow stimulation fails. For a small chondular lesion, it typically could still be an autograft transfer. For a larger chondular lesion, that's usually an osteochondral oligraft. And again, in the patellofemoral joint, if you do it, it may burn bridges to possible autologous chondrocyte implantation. So it may be more beneficial to choose to breathe it alone and possibly do an ACI biopsy in that setting. So why is microfracture becoming less and less prevalent, particularly among knee and articular cartilage surgeons? Well, there's been a number of studies that have shown poor outcomes at long-term follow-up, but especially poor outcomes in the athletic population, which is what we're oftentimes treating with some of these defects when we perform the index knee arthroscopy. So this was a well-known study published in the American Journal of Sports Medicine that showed 58% of subjects returned to play in the NBA for greater than one season, but 33% or one third of NBA players that had a microfracture performed were unable to return to competition, which is a high number for a very otherwise high-level athlete. So in general, the overall trend has been away from microfracture for full-thickness articular cartilage lesions. Jack Burt wrote a nice editorial commentary about abandoning microfracture in the knee entirely in the Arthroscopy Journal. I wrote a somewhat similar Inside Anna E. newsletter discussing the case against microfracture and being mostly a historical type of procedural choice with the exception of small defects, such as what we're talking about here, and patients that have relatively low demands and overall low expectations in terms of their activity level in the future or with their daily activities. So how about autologous osteochondral transfer, or what people typically term as osteochondral autograft transfer? It's a transfer of cartilage and bone to the defect site. The indications are grade 3 or grade 4 articular cartilage defects. The ideal lesion size is less than 1.5 centimeters squared, as there's only so much autograft articular cartilage that can be taken before you start to rob Peter to pay Paul. The harvest sites are typically the far superior lateral or medial trochlea, or the superior lateral aspect of the intercondylar notch, as you see pictured in the image on the bottom right. There are many benefits to an autograft transfer. First and foremost, it's mature, high-length cartilage, as opposed to the fibrocartilage you get with a marrow stimulation or microfracture. There's excellent bone and tissue incorporation, as it's an autograft tissue. It can be performed in a single-stage procedure, and it is relatively quick recovery. The limitations of an autograft transfer are that there is limited donor site availability. Again, you're not going to rob Peter to pay Paul, so that makes there be size limitations, and so it's really only indicated for some of these smaller lesions, like we've been talking about. There can be donor site morbidity, but you can sometimes bone graft or backfill the donor site to try and decrease that potential morbidity. The topography and curvature of the condyles in particular, but also the trochlea, as another example, oftentimes have mismatch, which can lead to graft incongruity, and the procedure itself can be technically difficult, whether you're doing it arthroscopically or whether you're doing it open or whether you're doing a mosaoplasty-type procedure, which utilizes multiple small plugs stacked on top of each other, as you see in the picture at the bottom right. What are the outcomes with osteochondral autograft transfer? Really overall, they're pretty good. This is a systematic review. You can see of the transplant outcomes, a total of nine studies, 607 patients. The results showed that osteochondral autograft transfer was most appropriate for lesions less than two centimeters squared, that the patients were able to return to sport as early as six months post-op, and when it was compared versus microfracture, the autograft transfer had superior clinical results and superior rate of return to sport and maintenance of sport function versus a microfracture procedure. This is another study published in the Journal of Bone and Joint Surgery with Aaron Kritsch as the lead author. This has 96 patients with femoral condyle or trochlear defects, half and half treated with osteochondral autograft mosaoplasty, and the other half with microfracture, average age pretty similar, and the results showed that osteochondral autograft transfer had significant improvement in marks activity at two-, three-, and five-year follow-ups, and patients treated with an osteochondral autograft retained superior level of athletic activity versus the microfracture cohort. So in conclusion, when it comes to microfracture and marrow stimulation, in 2021, it's relatively rare indications, really only for very small lesions and low-demand patients, and technique is very important if you are going to perform a marrow stimulation procedure. You want to create very small tunnels or channels, in other words, quote-unquote, a nanofracture type of technique, and don't violate the subchondral bone, and therefore creating edema in the subchondral bone. Also not an ideal procedure in young athletes, and not an ideal procedure for the patellofemoral joint. Versus autograft transfer or osteochondral autograft transfer, which is ideal for lesions less than 1.5 to 2 centimeters squared, it's really ideal most for femoral condylar defects to match the topography, and it's somewhat more difficult, not impossible, but more difficult in the patellofemoral joint, but is an ideal procedure for these smaller, isolated osteochondral full thickness defects. Thank you for your attention and for attending the course. As always, please feel free to contact me anytime, and reach out either via email or via social media using whatever account you prefer. Thank you.

cartilage injuries

microfracture

autograft transfer

rehabilitation protocols

patient expectations