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Knee Examination

Knee joint

Knee joint

Introduction

Knee examination is an important clinical skill, and knee problems are a common presenting complaint to general practice and emergency departments. Knee examination is also a common OSCE station.

The knee is a hinge joint, but it depends on external structures for its stability, including the cruciate and collateral ligaments, and the menisci.

Like moth orthopaedic examinations, a typical knee examination follows the Look, Feel, Move pattern.
As with all examinations – first ask the patient’s consent including explaining the need for and process of the examination.

Inspection (look)

First of all, uncover the knee joint (best if the patient wear shorts or underwear). Remember to uncover both knees so as to use the unaffected knee for comparison.
Start with the patient standing, and look for:
Ask the patient to lie supine (on their back) on the examination couch and look for:
Skin changes
  • Discolouration
  • Wounds (including old surgical scars)
  • Gross deformity
Soft tissue changes
  • Swelling – the three main causes of swollen knee are:
    • Bony swellings
    • Synocial thickening
    • Fluid collection e.g. in inflammation. Can be generalised (effusion), or localised (inflamed bursa).
    • Chronic diseases that can cause a swollen knee are:
    • Check the character and location of the swelling:
      • Localised – likely bursitis
      • Generalised – likely other cause
      • Translumination? – indicates presence of fluid
    • Quadriceps bulk – quadriceps often wasted in painful chronic knee conditions. You may want to measure the circumference and compare to the other leg, or compare over time. In these cases you shoulder measure 10cm above the patella.
    • Why do muscles waste in joint disease? – it is not solely due to lack of use of the muscle! The exact mechanism is not clear, however, it is thought that there is secondary nerve changes in the nerves around a diseased joint that mean the muscle wastes very quickly (perhaps within days!)
Bony changes

Palpate (feel)

The patient should be laid down on the couch. The angle of the backrest is not particularly significant. The knee should be full extended unless otherwise stated.

Move

Flexion and extension

Examining knee stability

Here we essentially examine the collateral and cruciate ligaments.
Collateral ligaments
Flex the knee to about 20’. Hold the ankle with one hand and the thigh with the other.

Cruciate ligaments

Lachman’s Test – assesses the anterior cruciate ligament 🎥
Anterior Draw test – assesses the anterior cruciate ligament
Posterior Draw test – assesses the posterior cruciate ligament

Meniscus tests

McMurray’s Test 🎥
With this test your are trying to trap the meniscus between the tibia and the condyle of the femur. Normally, this will not be possible, but if there is meniscal damage, it may be possible, and you will be able to feel crepitus, and to elicit pain.
With your left hand, palpate the medial joint line. Also use this hand to hold the thigh firmly in place.
Hold the ankle heel your right hand, and externally rotate the foot (everted), whilst applying varus pressure to the leg.  Now flex and extend the knee, feeling for crepitus in the joint.
Repeat the exam for the lateral meniscus – this time inverting the foot, and applying valgus pressure to the leg.
normally this test will elicit no pain, but in meniscal injury the patient may experience pain. A positive test may also be elicited if there is a clicking or popping sensation felt by the patient or examiner in the knee. It is important to FEEL for abrasions and crepitus in the joint as you are doing this – and in some cases the crepitus may also be audible. It is likely to be very painful if there is meniscal pathology!
Apley’s compression test 🎥
  • Lie the patient prone
  • Flex the knee to 90 degrees
  • Apply axial loading to the foot, whilst rotating the tibia
  • A positive test is indicated by pain, clicking or popping sensation in the joint, or restriction of rotation
  • A positive test indicates likely meniscal injury

Further special tests

Prone lying test

Quadriceps weakness

References

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