Hello, this is Andrea Spiker from the University of Wisconsin. I'm going to be discussing biological augmentation of meniscus repairs. What are the current options and what is the existing evidence? Here are my disclosures, none of which are relevant to this talk. The meniscus is a very important structure for knee load transmission, load distribution, stability, shock absorption, and protection against cartilage degeneration. The meniscus is made up of type 1 and type 2 collagen and an abundance of proteoglycans which give it its viscoelastic properties. Meniscus tears are very common and have a higher occurrence in males compared to females, affecting those aged 20 to 29 years at the highest rate. Medial, lateral, and middle geniculate arteries, which are branches off the popliteal artery, provide the major vascularization to the inferior and superior aspects of each meniscus. The peripheral 10 to 30 percent of the medial meniscus border and the peripheral 10 to 25 percent of the lateral meniscus border are relatively well vascularized and referred to as the red-red zones. Unlike the red-red zone, where a tear can heal by fibrovascular scar tissue within 10 weeks, lesions in the avascular zone have poor healing potential due to the lack of clot formation, interference by synovial fluid, and constant motion. The avascular zones are referred to as the white-white zones or sometimes the red-white zone. With age, the meniscus loses its elasticity and microscopic loss of cellular elements can initiate tears. After an attempt at conservative management, our surgical options for meniscus tears include meniscectomy, meniscus repair, or meniscus replacement. In these next few minutes, I'm going to focus on meniscus repair and what biologic augmentations are available for potential improvement of meniscus repair success. Repairs of vertical longitudinal or red-red zone tears have demonstrated good results, thanks to good vascularity in these areas. However, for tears extending into the avascular zone, there has been reported to be a 25 percent failure rate in patients younger than 20 years old, and in older patients, this has been reported to be nearly 36 percent of failure rates. The mean reported failure rate is about 15 percent after meniscal repair. Biological augmentation is an attempt to facilitate healing, given the limitations we encounter due to poor vascularity. The overall goals are to promote cellular proliferation and matrix production at the site of the repair. These are the biological augmentation options I'll go through next. The goal of synovial rasping is to induce a blood clot containing growth factors. In animal models, multiple studies have demonstrated increased healing when compared to either no mechanical stimulation or in one study compared to a fibrin clot. The goal of needle traffination is to introduce blood from the periphery to the avascular zone with the use of needle perforations. In 1993, Fox et al. described success in 30 patients using this as an alternative to suture fixation. However, about 74 percent of the patients in this study had tears in the outer third periphery of the meniscus, which theoretically have a high rate of healing regardless of augmentation. There's also a concern that this can damage the structural collagen integrity of the meniscus. The goal of bone marrow stimulation through drilling or tapping the intercranular notch is to introduce bone marrow contents into the interarticular space. We know that with ACL reconstruction, tunnel drilling accomplishes this and results in improved healing rates of meniscus tears and repairs. Meniscal repairs with bone marrow stimulation have been shown in at least one study to have comparable healing rates to those performed with concomitant ACL reconstruction. The goal of external fibrin clot is to juxtapose autologous fibrin at the site of repair to augment healing. Early reports have demonstrated up to 95 percent healing, but currently there are no definitive comparative studies. By injecting PRP or platelet-rich plasma into the joint, the hope is to introduce autologous growth factors into the healing environment. There has not been a consensus as to whether the evidence supports PRP or whether PRP makes no difference in healing of meniscus repairs. Also, there is significant heterogeneity in the reporting and preparation of PRP, which makes evaluation of outcomes much more challenging. Mesenchymal stem cells or MSCs can be administered on a construct or can be injected into the knee and do appear to have good healing potential. However, more evidence is needed before these can be used regularly in the clinical setting. The goal of biomaterial augmentation is to place a scaffold over the meniscus repair to encourage healing. Fascial sheaths and electrospun nanofiber scaffolds have been described in the literature. For the latter, more safety data is needed before we can use these regularly in the clinical setting. So in summary, there are many options for biologic augmentation of meniscus repairs, and while these have shown promising results with limited evidence that biologic augmentation appears to improve healing, we still need more evidence before we can definitively claim that one method of biologic augmentation can improve healing of meniscus repairs. However, there are many options for biologic augmentation of meniscus repairs, and while we still need more evidence before we can definitively claim that one method of biologic augmentation is the gold standard. Thank you.

biological augmentation

meniscus repairs

knee load transmission

meniscus tears

surgical options