Your knee has two C-shaped pieces of cartilage – called the meniscus – that help to cushion the shinbone and thighbone and support the joint. Forcefully twisting or rotating your knee – for example, by pivoting or turning sharply – can tear your meniscus.
A torn meniscus is a common sporting injury particularly in contact sports or sports that involve sudden changes of direction, such as tennis and basketball. Heavy lifting, squatting or even kneeling can also cause a meniscus tear and, in older adults and people who are overweight, sometimes even simple movements can produce a torn meniscus.
There are different ways that the meniscus can tear. If it is due to a traumatic injury, the tear is normally vertical whereas a torn meniscus associated with joint degeneration due to ageing generally produces a horizonal tear. Sometimes the meniscus may become so seriously torn it is shredded.
Symptoms of a torn meniscus
A torn meniscus is a painful injury. You might experience a popping sensation and feel like your knee is giving way. It may be hard to straighten your knee fully. Sometimes it can lock when you try to move it due to a fragment of the torn meniscus becoming lodged inside the joint and preventing it from moving freely.
What is an arthroscopic meniscectomy?
An arthroscopic meniscectomy is a minimally-invasive surgical procedure that is used to treat a torn meniscus. It is generally performed if the knee has become locked or is so swollen that it is preventing everyday activities.
Arthroscopic meniscectomy involves using keyhole surgery (arthroscopy) to remove or repair the torn section of the meniscus. Only the outer section of the meniscus has a blood supply. If the tear occurs in this section then a surgical repair is likely to be successful. However, if the tear occurs in a section of the meniscus without a blood supply then it is unlikely to heal, therefore, removing the damaged area is recommended. In the immediate aftermath, arthroscopic meniscectomy carries a risk of infection and deep vein thrombosis.
Long-term outcomes of arthroscopic meniscectomy
A group of researchers at the University of Turin in Italy set out to explore longer-term outcomes of arthroscopic meniscectomy. They were keen to discover whether, 20 years after surgery, patients experienced poor clinical outcomes, including the need to undergo a total knee replacement. Their findings were published in The Knee on 8 January 2021.
Research study
The research team collected data for 225 patients aged between 18 and 50 years. The patients had all had a meniscal tear and undergone arthroscopic meniscectomy. Researchers looked at a range of factors including the patient’s age when they had surgery, the extent of the injury and how much repair/removal was required. They then considered 20-year outcomes using the Knee Injury and Osteoarthritis Outcome Score (KOOS) and whether the patient had undergone a total knee replacement.
They discovered that 10 patients needed a total knee replacement. The average time between undergoing an arthroscopic meniscectomy and total knee replacement was seven years. Researchers identified a number of significant factors that appeared to link meniscectomy with subsequent knee replacement. Patients aged between 40 and 50 – particularly women, those with knee misalignment, a lateral meniscectomy, advanced chondral lesions and those who underwent a total meniscectomy were at particular risk of poor clinical results or total knee replacement.
What are advanced chondral lesions?
Cartilage – or chondral – damage is called a lesion. Lesions are graded from one to four. A grade 1 lesion is a small tear in the top layer of the cartilage while a grade four lesion is a tear that goes all the way through the cartilage to the bone. The research study found that the more extensive the meniscal tear, the greater the chances of needing a total knee replacement in later life.
