Professor Wilson explains the difficulties of examining the knee when it is acutely painful and swollen.

First published by knee surgeon Adrian Wilson in 2010, and reviewed August 2023 by Dr Sheila Strover (Clinical Editor)


Examining any knee needs to be tailored to the individual and the particular clinical scenario or problem -

  • For example, if a child walks into the consulting room one immediately starts to think about the paediatric knee and its association with, for instance, the hip and the spine, and the examination needs to be tailored very much in a specific way towards paediatric problems.
  • If someone sporty comes in, one immediately thinks of ligament instability, meniscal problems, chondral damage.
  • In an individual with a large swollen painful knee that has just flared up without any injury, one immediately thinks “Is this an infection or an inflammatory condition such as gout or the first presentation of an inflammatory arthropathy such as rheumatoid arthritis?”
  • In the elderly patient walking in with bandy legs, who is stiff and in significant pain, you tailor your examination towards the arthritic patient.


A good history together with a thorough clinical examination and some plain X-rays, will give you the answer about any individual’s knee problem in 95% of cases without the need for fancy scans and tests.


In the UK where I work there is a real tendency for individuals not to be properly assessed after an injury where an individual is running or walking, has a fall, a twist – and suddenly their knee becomes painful and swollen and they can’t weight-bear. In the UK, the most common place for a patient who has injured their knee to seek attention is either from General Practitioner (GP/family doctor) or via the emergency department (A&E). In A&E unfortunately you are unlikely to be seen by a doctor and much more likely to be seen by an A&E nurse, as there aren’t nowadays many doctors working in A&E! If you are lucky enough to see a doctor, that doctor is likely to be extremely junior. For anyone interested in the knee this is enough to drive one mad as there is a very simple message that if an individual falls over or twists their knee and have acute swelling (coming on suddenly) that needs to be taken very seriously and the patient needs to be thoroughly assessed to rule out major ligament injury or meniscal/chondral (cartilage) damage.

Well I don’t agree with this. To my mind if you are playing sport and you twist your knee – particularly if you hear a POP! And the knee suddenly swells which means there is bleeding inside the knee – you have torn you ACL until proven otherwise. You may also have torn other ligaments at the same time. Without proper management early on an easy problem to manage can become extremely difficult. If the swelling comes on more slowly, say overnight, then it is much more likely to be a meniscal tear or perhaps some joint surface damage and again this will be picked up by taking a thorough history in the early period after the injury.


Missed MCL injury - a common problem

A relatively common occurrence is to fall over and suffer a combination of injuries, and traditionally we have spoken about the ‘terrible triad’ of ACL, medial collateral ligament (MCL) and meniscal pathology. If you go to A&E with this diagnosis and the MCL injury is significant and missed, and you are not braced appropriately, then it’s much more likely that you are going to need to have surgical intervention for the medial collateral ligament injury. If, however, the medial collateral ligament injury was picked up, and that is relatively easy to do with clinical examination, then the knee needs to be braced in a slightly bent position, in which case 9 times out of 10 the ligament will heal uneventfully. Often patients have these injuries totally missed, and the patient can turn up as late as 18 months after the injury with chronic instability and then that is a major challenge for any knee surgeon.

At my hospital we regularly educate the nurses and doctors in A&E to encourage them to send the acutely swollen knees to our knee clinic where the patient can be seen by a knee specialist and the injuries as listed above – and which we will later talk about again – are picked up early and treated appropriately. Maybe we surgeons see a skewed population as we see the ones that don’t settle, but so many young people are coming into the clinic now aged 30+ finding that they have got chronic instability having had an injury five years before, and now they have wrecked their knee and are really beginning to run out of options.