34th Annual Scientific Meeting proceedings

The stifle menisci are critical to joint function. They enhance congruency between the femoral condyles and the tibial plateau, thereby increasing the surface area for load distribution and reducing mechanical stress within the joint. Additionally, they contribute to joint lubrication, stability, proprioception, and coordination of muscle contraction. The menisci also serve as primary passive restraints against cranial tibial translation.

Anatomically, the stifle menisci are two C-shaped fibrocartilaginous structures anchored within the femorotibial joint by ligamentous attachments to the tibia, the femur, and to each other. Their function relies heavily on these attachments at both ends of the C-shape, which allow them to deform under hoop stress and displace abaxially under load. If these attachments are compromised—such as through a meniscal release—this unique biomechanical function is impaired.

The medial meniscus, being more firmly anchored and less mobile than the lateral meniscus, is more susceptible to injury during cranial tibial translation. This often results in a bucket-handle tear of its caudal horn. Meniscal tears are most commonly associated with cranial cruciate ligament disease (CCLD)—one of the most frequent orthopedic conditions in dogs. While lateral meniscal injuries also occur, they are less well-documented and their clinical significance remains uncertain. However, they occur frequently without involvement of CCLD, but often have significant cartilage erosion in the lateral compartment of the stifle.

Only the abaxial 15–25% of the adult meniscus, known as the red-red zone, is vascularized. This vascular anisotropy significantly limits the healing potential of tears located in the avascular inner regions. Structurally, the meniscus has a triangular cross-section, with a thick abaxial rim that tapers to a thin, nearly translucent axial edge. On the microscopic level, the collagen type I fiber orientation varies by region, resulting in anisotropic dynamic mechanical properties (e.g., storage and loss moduli), as demonstrated in both human and bovine studies.

Treatment of meniscal injuries in veterinary medicine is largely based on expert opinion, as high-quality evidence remains limited. Currently accepted options for medial meniscal pathology in dogs include debridement of partial or complete tears of the caudal horn, or meniscal release via transection of the midbody or meniscotibial ligament. While caudal-pole hemimeniscectomy and meniscal release can provide short-term clinical improvement, long-term outcomes may include joint deterioration, as shown in canine models.

In human medicine, meniscal suturing is a well-established procedure, typically performed arthroscopically using commercially available instruments and implants, with variable success rates. Although meniscal suturing has been described in dogs, it is not widely adopted, and no standardized techniques have been established. The most commonly used method is the "inside-out" technique, in which a needle is passed arthroscopically through the damaged meniscal region into healthy tissue, and the suture is tied externally through a separate skin incision. This approach offers two key advantages: first, the needle can be placed under direct visual control at the precise location within the meniscus; second, the knot—challenging to perform and ideally positioned away from the meniscus to avoid irritation—can be tied externally.

The canine meniscus has been studied as an experimental model for human meniscal repair, with both open and arthroscopic techniques described in veterinary literature—though outcome data remain sparse. Only specific tear types are considered suitable for repair, particularly those involving the meniscocapsular junction, the caudal meniscotibial ligament, or parenchymal tears located within or adjacent to the vascular zone.

Osteochondral allograft transplantation, including the meniscus, has been successfully performed in dogs, though primarily in research settings and only occasionally in clinical practice. One ongoing challenge is donor availability; ideally, the donor should be a dog of similar size, both for ethical and practical reasons. Nevertheless, studies have shown that dogs receiving such grafts exhibit improved gait, reduced pain, decreased osteoarthrosis progression, and minimal complications.

In human medicine no clear superior technique to treat torn menisci has been identified. Same as in dogs tear location and morphology are highly affecting success rates when it comes to meniscal repair and regeneration. Augmentation techniques to enhance meniscal repairs aim to promote healing or tissue regeneration be modulating the biological environment. Most commonly approaches used include stimulation of bleeding and scar formation at the repair site, as well as the use of autologous blood products (such as platelet-rich plasma [PRP]), marrow stimulation techniques, fibrin clots, and cellbased therapies, such as bone marrow aspirate concentrate. No clear evidence is available to give clear guidelines. In human medicine is clinically available by also not broadly used.