Meniscal
tears
Meniscal tears are a common clinical finding in dogs. Injuries usually involve the medial meniscus and typically occur following cranial cruciate rupture.
Meniscus
The stifle (knee) joint sits between the femur (thigh bone) and tibia (shin bone) however they are not very well designed to fit together. To improve the fit two c-shape structures sit in the joint called the menisci (or meniscal cartilage). They are made of a rubbery cartilage that, as well improving the fit of the joint, acts as a shock absorber. There is a medial meniscus on the inner side of the joint and a lateral meniscus on the outer side.
Meniscal Tears
In people, meniscal tear is a common sports injury with people who do a lot of twisting and turning, the meniscus can also degenerate over time. In dogs, while we do see isolated meniscal tears, the most common presentation is in dogs with cranial cruciate ligament rupture. Meniscal tears are identified in approximately 20%-77% of dogs with cruciate ruptures. When the stifle becomes unstable, as the tibia moves forwards and backwards, it is easy for the meniscus to get trapped and torn. Most commonly the medial meniscus is torn as it is more firmly attached to the tibia. Meniscal tears cause lameness on their own, and contribute to the lameness when seen in dogs with cruciate ruptures. Sometimes a popping or clicking noise/sensation is noted when the stifle is manipulated.
While you can detect meniscal tears using advanced imaging (MRI and CT) ref, the most common way to diagnose meniscal tears associated with cruciate ruptures in dogs is to look in the joint at the time of surgery at the time either via an arthrotomy (small opening in the joint capsule) or arthroscopically (using a keyhole camera). If the meniscus is normal, no further treatment is required. If a meniscal tear is diagnosed, generally they are treated by removing the torn portion (partial meniscectomy). Dogs with long term meniscal tears have been shown to get meniscal tears end up with a bit more osteoarthritis than those that don’t, but generally they cope well.
While you can detect meniscal tears using advanced imaging (MRI and CT) ref, the most common way to diagnose meniscal tears associated with cruciate ruptures in dogs is to look in the joint at the time of surgery at the time either via an arthrotomy (small opening in the joint capsule) or arthroscopically (using a keyhole camera). If the meniscus is normal, no further treatment is required. If a meniscal tear is diagnosed, generally they are treated by removing the torn portion (partial meniscectomy). Dogs with long term meniscal tears have been shown to get meniscal tears end up with a bit more osteoarthritis than those that don’t, but generally they cope well.
Late Meniscal Tears
In a small number of dogs that have a normal meniscus we recognise a problem called a late meniscal tear. This is a tear that occurs after the time of surgery. We see this in between 2%-22% depending on the procedure. Affected dogs tend to be doing well then go suddenly lame again. If a late meniscal tear is suspected it can be diagnosed by advanced imaging (CT or MRI) but they can be difficult to see, particularly if implants were placed at the time of surgery. In most cases the easiest way to diagnose a late meniscal tear is to look in the joint again, either via an arthrotomy (small opening in the joint capsule) or arthroscopically (using a keyhole camera), and remove the torn portion. Most dogs recover well from this procedure (ref).
If you have any questions about Meniscal Tears please speak to your vet.
If you have any questions about Meniscal Tears please speak to your vet.
References
McCready DJ, Ness MG. Systematic review of the prevalence, risk factors, diagnosis and management of meniscal injury in dogs: Part 1. [corrected]. J Small Anim Pract. 2016 Feb;57(2):59-66. doi: 10.1111/jsap.12433. Erratum in: J Small Anim Pract. 2016 Apr;57(4):221. PMID: 27168486.
McCready, D. J., & Ness, M. G. (2016). Systematic review of the prevalence, risk factors, diagnosis and management of meniscal injury in dogs: Part 2. The Journal of small animal practice, 57(4), 194–204. doi.org/10.1111/jsap.12462
