Jargon buster: how to understand knee conditions

The knee is a complex joint so it can be no surprise why it’s such a common problem. With so much information (and jargon) out there, it can be difficult to know where to start with your research. To help get you started we asked knee specialist, Mr Ed Tayton, to break down the medical terminology and give an insider’s guide to knee problems.

How to understand medical terminology around knees

Although medical terminology can appear confusing, I find it helpful to explain the origin of the words to patients. So for instance:


The first part “arthro” means joint, and “scopy” refers to a camera being used. A knee arthroscopy is therefore commonly called keyhole knee surgery, a surgical technique to examine and treat knee conditions.


The “plasty” part of this refers to the joint replacement. So a knee arthroplasty will refer to a total or partial knee replacement.


This is closely linked with arthroplasty, as an arthrotomy refers to opening up the joint for surgery. You would therefore perform a knee arthrotomy to complete a knee arthroplasty.

Unicompartmental knee replacement 

The term unicompartmental refers to a half, or partial, knee replacement being performed.

Tendons and ligaments

A simple way to differentiate the two is that the tendon attaches a muscle to a bone, and a ligament attaches a bone to a bone.


Two moon shaped bits of cartilage which act like shock absorbers and help protect the overlying joint articular cartilage in your knees.

Articular Cartilage

This is a substance which covers the end of each bone in the joint. It is a bit like the tread on a car tyre.

What’s involved in a knee arthroscopy?

A knee arthroscopy is what we call a “minimally invasive” procedure, in comparison to open surgery, such as a knee replacement. It involves making small incisions, and inserting a tiny camera into the knee, so surgery can be performed with only minimal access required. It is usually a daycase procedure, meaning you can leave hospital the same day following your operation.

The main advantages of keyhole surgery are:

  • It’s minimally invasive, so muscles won’t need to be cut
  • Shorter surgery time, usually around 30 minutes
  • Lower risk of infection, due to smaller holes
  • Pain control is generally better than open surgery
  • You will usually recover quicker than having open surgery. For a common procedure, such as to deal with a meniscal (cartilage) tear, you can expect it to take two weeks to return to a desk job and four to six weeks to get back to full labour.

How do you know if you have a knee problem?

If you have persistent pain or instability in your knee, it’s likely you need some treatment. Instability is usually caused by a ligament injury, so your knee may feel like it’s giving out on you when you walk, twist, turn or use stairs. It can also be difficult to balance properly. The other common symptom is knee pain, which has numerous causes, but a meniscal tear or knee arthritis are by far the most common conditions treated.

What are the best, and worst, sports for knees?

The worst sports for knees are impact sports. Typically, patients usually think of rugby when I say this but running, tennis and squash would all fall under this category. Consistent pounding, twisting and jumping can put a lot of strain on the joint, so I would advise against these sports if you have a knee problem.

The worst thing you can do is ignore knee pain and try to “run through it” – if you develop knee pain from an injury or when performing sports, you should stop and speak to a medical professional to advise you on the next steps.

On the flip side, cycling is pretty much the perfect sport if you have knee problems. There’s growing evidence that if you cycle consistently, this will help to keep your knee pain at bay. Swimming is also great, but be careful to avoid breast stroke as this puts a twist and added torsion on your knees. Instead, swimming front crawl is usually better as your joints are in line.

What are the main knee conditions?

There are many different knee conditions I see with patients, but they usually fall under one of these four broad categories:

1) Tendonitis (tendon inflammation)
2) Ligament injury/rupture, causing instability of the knee
3) Cartilage/meniscal injuries 
4) Degenerative conditions, such as arthritis.

What is a torn meniscus and arthritis?

To explain what these conditions are, it’s often helpful to use a car tyre and shock absorbers as an analogy.

On the ends of your leg bones in the knee you have a layer of joint lining (or articular) cartilage. This acts like tread on a car tyre, which gets thinner and thinner as you get older. Essentially when the tread runs out, you’ve run out of cartilage and this is arthritis. It is likely you will require a joint replacement (arthroplasty).

To protect the car tyres between your leg bones, sit your menisci. These are two moon shaped bits of cartilage which act like shock absorbers and help protect the overlying joint lining cartilage. The menisci have three main functions in the knee – protection, stability and lubrication of the joint.

It is possible to damage or tear your meniscus, and this is a common reason patients come to see a knee specialist with pain. It is usually caused by an injury such as a twist during sporting activity, but as you get older the meniscus gets stiff and brittle, meaning a much smaller force is required to damage it. Minor activity such as simply stepping off a curb awkwardly, or crouching down, can be enough to cause damage.

For all types of tear, surgery is usually needed although it depends on the patient as to whether it can be repaired or whether it should be surgically removed to resolve the issue. A knee arthroscopy would usually be performed to complete this procedure, so in this case it would be an “arthroscopic meniscectomy” (surgically removing torn part of the meniscus from the knee).

Getting an early diagnosis & effective treatment

If you develop acute knee pain, you should first consult your GP (or attend A&E if it’s a serious injury or emergency). Usual initial advice includes the standard RICE treatment (rest, ice, compression and elevation), and then a referral to physiotherapy, which can often take some time to organise. However, for a large number of patients this will never be enough to solve the issue. Therefore, getting an early and accurate diagnosis is key, so correct treatment can be initiated from the start. If the knee pain has not settled within a couple of weeks you should seek a knee specialist’s advice.

During an initial consultation, a careful look through the history and a thorough examination will be performed. This will indicate a condition but most patients require specialist investigation, usually in the form of an MRI scan, before a final diagnosis can be made.

Many knee conditions can be treated with conservative measures, such as physiotherapy, which is a good starting point. However, many injuries and conditions require early surgical intervention, hence the importance of an early and accurate diagnosis.

24th August 2017

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