Arthroscopy & Meniscal Tears

The most common reason for a knee arthroscopy is to deal with a torn meniscus. Most meniscal tears which need surgery are treated with a simple debridement (or trim) of the torn portion of the meniscus. Other reasons for arthroscopy include: washing out an infection, removing loose bodies or sampling the lining of the joint as a biopsy. More complex procedures such as repair of meniscal tears, or cartilage defects or even cruciate ligament reconstructions can be done arthroscopically.

This varies according to what was actually done inside the knee. For most simple arthroscopic procedures with trimming of torn cartilage, weight bearing is allowed but with 2 weeks of taking it easy to let the portals heal. More complex procedures such as repairs or reconstructions may need time non-weight bearing or with other restrictions.

A meniscus is the shock absorbing cartilage in the knee. There are two, one on the medial side and one on the lateral side. They act as a cushion and almost like an adaptor between the flat top of the tibia (shin bone) and the curved end of the femur (thigh bone).

Like all injuries, menisci can be torn from a sudden major knee injury or from gradual wear and tear. For example, around half of ACL injuries have some sort of meniscal injury too. The other type of injury is a chronic wear and tear – an accumulation of minor injuries which eventually damage the meniscus.

Like skin wrinkling, meniscal wear is a normal part of ageing. Only tears which cause symptoms may need surgery. The typical symptoms from a meniscal tear are mechanical symptoms; clicking, clunking, a feeling of instability or the knee physically getting stuck.
The meniscus has a poor blood supply and so has a limited capacity for healing itself. Almost all symptomatic tears in younger patients with healthy knees do benefit from surgery. In older patients or those with worn out knees, some tears can be left alone while others which cause symptoms can benefit from surgery.

Some tears are repairable. This depends on the nature of the tear, where exactly it is and what the condition of the rest of the knee is like. Depending on the exact tear configuration and stability of the repair, sometimes a period of protection with crutches or even non-weight bearing for 6 weeks is needed. Because of this, most meniscal repairs are planned ahead of time. It is rare to go into surgery expecting to simply trim a meniscus but instead finding that it is repairable. There are many ways to fix a meniscus depending on the type and location of the tear. Common methods include using suture devices completely inside the knee, through tunnels in the bone, or through larger incisions on the knee.

Tears which are not repairable (the majority) are trimmed back to a stable base. Removing the whole meniscus (as was historically done) improved symptoms quickly but had a high risk of progressing to knee arthritis. Nowadays only the torn portion of the meniscus is removed, leaving behind as much meniscal tissue as possible as long as it is stable and functional. It is much like having a torn fingernail and just trimming the torn portion to make the edge smooth.

The trend has now moved away from arthroscopy for uncomplicated knee arthritis. Osteoarthritis is a wear and tear process where the cartilage in the knee wears aways. This includes the smooth cartilage on the ends of the bones as well as the meniscus. Unless there are obvious mechanical symptoms (clicking, clunking or locking) which can be attributed to a meniscal tear or loose cartilage flap, arthroscopy is unlikely to make a significant difference. Also, in the setting of arthritis, pain may persist even after a meniscal tear is dealt with as some of the pain may be coming from the arthritis rather than the torn meniscus.