Canine Meniscus Update

Meniscal injury in the dog is most commonly associated with cranial cruciate ligament (CrCL) insufficiency. The reported incidence varies from 33.2% to 77 %. In a recent study reporting a series of 1000 dogs treated for CrCL insufficiency, 33.2% of dogs presented with a meniscal tear diagnosed at the time of the first surgery. The sex distribution was 39.7% neutered males, 32.2% neutered females, 13.7% intact males and 13.4% intact females. Isolated meniscal tears are very rare but have been reported in Boxers, working dogs and in association with osteochondral lesions. When CrCL insufficiency is present, the medial meniscus is more commonly affected than the lateral meniscus. Lateral radial tears have been also reported with an incidence of 77%. Their significance is unknown as frequently are limited to the free axial edge. Another clinical presentation of meniscal injury is as a late complication of surgical management of the CrCL-deficient stifle joint. Postliminary medial meniscal tears may be a result of residual stifle joint instability and latent tears represent a failure of diagnosis at surgery. These tears may result in persistent lameness and require additional surgical treatment. The incidence of postoperative meniscal injury has been reported for several surgical techniques, and it varies between 2.8 % and 17.4 %. Clinical manifestation of postoperative meniscal injury is usually within the first 4 months after surgery, and in most cases requires surgical intervention. There are only a few large epidemiologic studies evaluating incidence and risk factors for meniscal injury in dogs. No association between meniscal injury and breed, sex and tibial plateau angle has been found. The existing clinical data suggest an increased incidence of meniscal tears in overweight dogs, and in dogs with chronic and complete CrCL ruptureThe menisci provide several vital functions in the stifle, including load bearing, load distribution, shock absorption and joint stability. Their wedge shape is ideal to act as a spacer between the femoral condyle and the tibial plateau, and when there are no compressive weight-bearing loads across the joint, limit contact between the articular surfaces. Under static-loading conditions, the menisci assume a significant load-bearing function in the stifle. The larger contact area allows the menisci lower the stress of the cartilage, protecting against mechanical damage to both the chondrocytes and extracellular matrix. Together, the menisci bear between 40% and 70% of the load across the stifle.