The meniscal cartilages (the menisci) are two C-shaped wedges of elastic cartilage sitting inside the knee, in between the bones, like rubber washers. They act as load sharers, shock absorbers and secondary stabilisers in the knee, and they probably also have a role in proprioception (reflexes), lubrication of the joint and nutrition of the articular cartilage. The medial meniscus sits inside the inner (medial) side of the knee. The lateral meniscus sits inside the outer (lateral) side of the knee.
The menisci are put under immense pressure in the knee with movements, particularly with impact and twisting on a bent knee. Meniscal tears are one of the most common injuries that a knee surgeon will see, and they frequently occur in association with sports such as football, netball, squash and skiing. In addition, as you get older the meniscal cartilages begin to become progressively more degenerate, and they start to lose some of their elasticity and become weaker, more friable and more liable to tear. Degenerate meniscal tears are common in people over the age of 40. About 50% of degenerate meniscal tears occur spontaneously, without any history of any trauma; with the other 50% there is often a history symptoms after a minor twist, or even after just squatting or kneeling (e.g. with gardening or with cleaning the floor).
Meniscal tears can cause a whole batch of symptoms, and this can include all or some of the following:-
- giving way
The pain associated with a meniscal tear is often a deep, dull, constant achy pain plus intermittent sudden sharp pains. The sharp pains tend to come on particularly if you twist on the knee. The pain is normally located over the inner (medial) side of the knee for a medial meniscal tear, and the outer (lateral) side of the knee for a lateral meniscal tear. Tears of the back part of a meniscus (the posterior horn) are very common, and with these the pain is often around the back of the knee (posteriorly), and frequently more difficult to localise precisely. Also, with posterior horn meniscal tears there is often pain with forced deep flexion of the knee, e.g. with deep squats.
Meniscal tears are often associated with swelling of the joint, which is called an ‘effusion’. With acute meniscal tears from a specific accident, the swelling tends to be only small to moderate (but not large, as occurs after a ligament injury such as an ACL tear). Also, the swelling often comes on not immediately (or within the first few minutes) after the accident (as is the case with an ACL tear), but instead people tend to notice the swelling later that evening or sometimes not until the following day. With the less acute knee, there might be intermittent swelling that is only noticeable after episodes of attempted exercise. The swelling from an effusion affects the whole joint and is therefore widespread and diffuse, not localised to just one spot around the knee. The synovial capsule of the knee extends above the patella at the front of the knee, and it is often here (in the suprapatellar region, just above the kneecap) that the effusion is most obvious and apparent.
Painless clicking or crunching in a knee is normally due to roughness of the articular cartilage on the joint surfaces or due to small bits of soft tissue from the lining of the knee catching as the joint moves. Painless clicking is not normally a worry or concern, as long as it’s not associated with other specific symptoms such as giving way or locking. Painful clicking, however, is a sign that there is probably something torn or unstable inside the knee joint – and therefore this is a symptom that should be taken seriously and that should prompt further investigation of the joint.
If you can feel something catching inside the knee, then again – this is a significant symptom that implies that there is something torn, unstable or loose inside the knee … and this does justify further investigation.
Broadly speaking, there are two general types of giving way. If the knee feels generally wobbly and unstable, if you have no confidence on it and if the joint gives way (i.e. the knee ‘gives out’ and you either fall or stumble) intermittently, then this is quite often due to ligamentous instability i.e. there is a ligament (most frequently the ACL) inside the knee that is torn. If, however, the knee is OK most of the time, but intermittently there is a sudden sharp pain and a feeling of giving way, particularly with twisting or turning on the knee, then this is more often due to a torn meniscal cartilage. Giving way is a serious symptom, as not only is there a risk that you might fall over and hurt yourself, but every time a knee gives way there is the very real risk of further damage being caused inside the knee. Patients with giving way of a knee are very likely to need further investigation and quite probably surgery.
Locking is where you go to straighten your knee but something gets caught/trapped inside the joint, preventing you from being able full extend (straighten) the joint. Sometimes locking is an intermittent thing, and if the knee is ‘wiggled’ around then there might be a clunk inside the joint, with something ‘going back into place’, after which the knee can then be straightened again. Locking implies strongly that there is something significant either torn and unstable or actually loose inside the knee – and the most common causes are an unstable meniscal cartilage tear or a loose piece of bone and/or cartilage. If a knee is fixed in a locked position then it is not appropriate to just leave the joint or just try physiotherapy treatments … a locked knee needs an MRI scan ASAP (within days at most, not weeks) and almost certainly a knee arthroscopy to actually sort out whatever inside the knee is causing the locking.
The best investigation by far to show up a potential suspected meniscal cartilage tear is MRI scanning.
If a knee looks arthritic, then it’s appropriate to get a set of X-rays. If the X-rays confirm significant arthritis in the joint, then there might not be any real need for an MRI scan as well – as if there is significant arthritis and the patient has meniscal-type symptoms in their knee, then you can almost guarantee that there will also actually be a degenerate meniscal tear in the joint as well as the arthritis, as well as rough, unstable or loose bits of articular cartilage damage.
- Shoe inserts, orthotics or stupid bits of bobbly rubber stuck on the sole of your shoe cannot cure a meniscal tear!
- Physiotherapy, osteopathy or any other kind of manual therapy cannot cure a meniscal tear!
- Knee injections (steroid or hyaluronic acid) cannot cure a meniscal tear!
- The only proper treatment for a meniscal tear is a knee arthroscopy (keyhole surgery).
Not all meniscal tears necessarily need a knee arthroscopy --- the decision as to whether or not to have a knee arthroscopy depends on the severity of your symptoms, the degree of any functional restriction, what job/sports you do (and at what level) and what your expectations/demands might be. Any meniscal tear that is causing significant symptoms or functional restriction and that is either not getting better with time or that is actually getting worse, is going to need a knee arthroscopy.
Knee arthroscopy is a relative small day case operation, performed under a general anaesthetic. A telescope and probe are passed into the knee joint through two small (5mm) incisions at the front of the knee. The whole of the inside of the knee is inspected, and damaged areas can be probed. When a meniscal tear is found, then this will either be stitched back together and repaired or, if the tear is not repairable, then it will be trimmed smooth and stable with a partial meniscectomy.
CLICK HERE for more information about knee arthroscopy
CLICK HERE for information about meniscal trimming
CLICK HERE for further information about meniscal repair