Knee arthroscopy and meniscus tears

What the meniscus is

Each knee has two menisci, one on the inner side and one on the outer. They are two crescent-shaped rubbery cushions that absorb shock and spread the load between the thigh bone and the shin bone. Without them, cartilage wears out faster.

How a tear happens and what you feel

In younger people a tear usually comes from a sudden twist of the knee, often in sport. Later in life the meniscus is already worn and can tear with a simple movement, like a deep squat.

• Pain on the inner or outer side of the knee, mostly when twisting or squatting.
• Swelling that appears over the next hours or days.
• Locking: the knee gets stuck and will not straighten.
• A feeling that something catches inside the joint.

Types of tear

Not all tears are alike, and the type decides the treatment.

• Longitudinal tear. It follows the curve of the meniscus. At the outer edge, where there is blood supply, it can often be stitched.
• Bucket-handle tear. A large piece flips towards the centre of the knee and locks it. It needs treatment soon.
• Radial and flap tears. They cut across the meniscus or at an angle. The unstable part is usually removed.
• Degenerative tear. A frayed meniscus in a worn knee. Usually treated without surgery.

Meniscus root tears

The root is where the meniscus anchors to the bone. When it tears there, the meniscus loses its ability to spread load, like a barrel that has lost its hoop. The knee behaves almost as if it had no meniscus, and cartilage wear speeds up.

It often appears after the age of 50, with a sudden pain at the back of the knee during a deep squat. When the cartilage is still in good shape, fixing the root back to the bone is worth discussing.

Diagnosis

It starts with a clinical examination. An MRI scan shows the type and position of the tear, along with the state of the cartilage and ligaments. With that information we decide whether treatment without surgery is enough.

Is surgery always needed?

No. Degenerative tears without locking are often treated with physiotherapy, strengthening and a change in activity. Surgery is discussed when the knee locks, when symptoms persist despite treatment, or when the tear can be stitched and the meniscus is worth saving.

What treatment without surgery involves

• A few days of relative rest, ice and raising the leg while the knee is swollen.
• Physiotherapy focused on the quadriceps and the hip muscles.
• Avoiding deep squats and sudden twists for a while.
• Painkillers or anti-inflammatory medication for a short time, under medical guidance.
• In selected cases, an injection treatment into the joint.

We usually give it six to twelve weeks. If the knee calms down and does not lock, nothing more is needed.

Meniscus and osteoarthritis

In a worn knee, the MRI almost always shows a meniscus tear as well. That does not mean the tear is the cause of the pain.

Large studies have shown that in degenerative tears, keyhole removal of the meniscus gives no better result than a good physiotherapy programme. That is why it is not offered as a first choice. Arthroscopy has a place when there is a mechanical problem, meaning a knee that truly locks. If the wear is advanced, the conversation is about a knee replacement.

Arthroscopy: repair or partial meniscectomy

Arthroscopy is done through two or three small incisions. A camera shows the inside of the knee on a screen and the surgeon works with fine instruments.

• Meniscus repair: when the tear sits in a zone with good blood supply, the meniscus is stitched and kept. Recovery is slower, but the knee is protected in the long run.
• Partial meniscectomy: only the torn, unstable piece is removed. The return to activity is quicker.

The aim is to keep as much healthy meniscus as possible. The same technique is used for cartilage damage, for example with mosaicplasty (OATS).

The day of the arthroscopy

The operation is done under spinal or general anaesthesia and usually takes less than an hour. Through two or three incisions of a few millimetres, the surgeon checks the whole knee: menisci, cartilage and ligaments. The final call between repair and removal is made at that moment, based on what the camera shows.

Most people go home the same day, with instructions on ice, exercises and weight bearing.

What else is treated by arthroscopy

• Cartilage damage. Smoothing, microfracture or transfer of bone and cartilage plugs (mosaicplasty, OATS) for focal defects.
• Loose bodies. Small pieces of cartilage or bone that float in the joint and lock it.
• ACL tears. ACL reconstruction is done with the same technique.
• Synovitis and plicae. Inflammation or thickening of the joint lining that causes pain and swelling.

Recovery

After a partial meniscectomy most people walk comfortably within days and return to their activities within a few weeks. After a repair the knee is protected for some weeks with crutches and limited bending, and the return to sport takes a few months. The exact programme depends on the tear and is set by your surgeon.

Work, driving and sport

After a partial meniscectomy, desk work usually starts within a week and driving once you control the leg comfortably. Running returns in four to six weeks.

After a repair the programme is slower, to give the meniscus time to heal: crutches and limited bending for some weeks, and a return to pivoting sports in four to six months. Patience here protects your knee for the years ahead.

When to call straight away

Most aches after surgery are expected. Some signs, though, should not wait for the next appointment:

• Pain, swelling or warmth in the calf that was not there before.
• Chest pain or shortness of breath. In that case call 166 (or 112) at once.
• Fever, or a wound that turns red, feels hot or leaks fluid.
• A knee that suddenly swells a lot, or pain that grows instead of easing.

If you are not sure, call. One phone call too many bothers nobody.

Myths and facts

• Myth: “Every meniscus tear needs surgery.” Fact: Many, especially degenerative ones, are treated without an operation.
• Myth: “Better to take the whole meniscus out.” Fact: The more healthy meniscus stays, the better the cartilage is protected.
• Myth: “Arthroscopy cleans out arthritis.” Fact: It does not reverse wear and is not offered for that purpose.
• Myth: “I can walk, so I have no tear.” Fact: Most people walk normally. Symptoms show up on twisting and deep squatting.

What to ask your doctor

• What type of tear do I have and in which zone of the meniscus?
• Can it be stitched, or will a piece be removed?
• What state is my cartilage in?
• Is it worth trying physiotherapy first?
• When will I return to my work and my sport?

Common questions