Knee examination

Introduction

Introduce yourself, confirm the patient’s name and date of birth. Explain the examination, obtain consent and a chaperone and then proceed to wash hands.

Ask whether the patient is in any pain, especially in the knee, and ask them to report if they have pain at any point of the examination. Expose both lower limbs entirely, allowing the patient to keep their undergarments on.

For all orthopaedic examinations remember: Look Feel Move Test.

Inspection

General inspection

Check if the patient is comfortable at rest. Assess their body habitus; obesity is an increased risk factor for disease of the weight bearing joints. Look around the bed for any walking aids.

There are 5 parts to inspection of the knee. It is recommended that you carry out the exercises which require standing first, before proceeding to examine the patient on the bed.

Assessment of gait

Ask the patient to walk 5m, first using any walking aids, and then without them, if it is possible.

Analysis of gait can help identify whether there are any symptoms of pain, weakness, limited range of movement, instability or discrepancy in leg length that you need to be aware of for the examination.

Antalgic gait: Also known in layman’s terms as a limp. The patient walks in a manner to avoid pain. They will have a shortened "swing phase" and will attempt to reduce weight bearing on the affected leg.

High stepping gait: Injury to the common peroneal nerve may occur with trauma to the knee. This will result in foot drop on the affected side as the patient is unable to dorsiflex at the ankle joint. Whilst walking, the patient will naturally attempt to compensate for this by raising their leg higher, resulting in a high stepping gait.

For other nerve-associated gaits, see the lower limb examination page for more details.

Closer inspection of the knee

Standing inspection

Ask the patient to stand still whilst you move 360o around the them to assess for knee alignment deformities and asymmetry, muscle wasting, swelling and scars.

A good acronym to remember what to look for is DAWSS. This stands for deformity, asymmetry, wasting, swelling or scars.

Alternatively, you can ask the patient to turn 90o at a time so that you do not need to circle them to inspect.

When performing an examination of both limbs, it is usually best practise to start by examining the “good” limb first, as this way you gain an appreciation for what is considered as “normal” for that patient.

Anterior view

Look for any knee malalignment issues such as:

Observe the quadriceps femoris muscle for any wasting. This may be due to injury or nerve damage, but most commonly occurs with underuse of the muscle. Finally check for any incisional or arthroscopic scars, which are present following knee surgery.

If you see a scar, identify its precise anatomical location, size, shape (if nonlinear), contour and appearance of surrounding skin.

Varus and valgus deformities are caused by pathologies affecting the menisci, such as osteoarthritis or a tear, or otherwise affecting nearby bone, such as trauma, infection, degenerative disease (such as Paget’s disease of the bone) or a growth plate injury suffered in childhood.

Lateral view

Knee hyperextension and fixed flexion deformities may be more easily observed from the side.

Posterior view

Observe surrounding muscles for any wasting. Again, check for any scars.

Closely inspect the popliteal fossa for any swelling, which could be due to a popliteal (Baker’s) cyst or popliteal aneurysm.


Popliteal cyst: A popliteal, or Baker’s cyst is a build-up of synovial fluid in a bursa in the posterior aspect of the knee. The most common cause is arthritis of the knee; however, it may also occur post-injury.

Popliteal aneurysm: A aneurysm affecting the popliteal artery. Under normal circumstances, the popliteal artery is usually quite difficult to palpate. If an aneurysm is present however, the artery will be strongly pulsatile.

Lying inspection

Set the bed at a 45o angle and ask the patient to lay down with their knees fully extended. Once again look for any muscle wasting and any knee malalignment issues such as a fixed flexion deformity; the patient will be unable to touch the back of the knee to the bed despite maximal effort. Perform a closer inspection for any swellings or scars. Anterior knee swelling may be due to a multitude of pathologies, osteoarthritis, rheumatoid arthritis, bursitis and gout to name a few.

Closely observe the skin for any bruising, a common finding following trauma, especially if there has been a cruciate ligament tear. Check the anterior aspect for any psoriatic plaques (dry, scaly, red/silvery skin). Eczematous rashes, if present, will be found on the skin folds of the posterior knee.

Finally, observe the patellar alignment. Normally the patella is in the centre of the knee, but if it is found on off centre, it may be a sign of sublaxation, dislocation or patellar tracking disorder.

Patellar alignment will be assessed more sensitivity later, during palpation.

Patellar tracking disorder occurs when the patella deviates with knee flexion or extension. The deviation is most commonly lateral but may also be medial. The cause is multifactorial, and may be due to muscle imbalances, loose tendons, cartilage degeneration or a combination of these.

Assessment of quadriceps femoris bulk

Reduced bulk of the quadriceps femoris is very suggestive for knee pathology. Knee pain and/or weakness that limits its use will result in wasting. Using a measuring tap, identify a point roughly 20cm superior to the tibial tuberosity on one limb. Record the girth (circumference) of the quadriceps femoris muscle at this point and then repeat this on the other limb. If the girths are similar, this suggests either no, or bilateral pathology affecting both knees.

The tibial tuberosity is the bony prominence on the anterior aspect of the leg which acts as the distal attachment of the patellar ligament

Palpation

Assessment of temperature

Using the back of your hands, palpate both knees at the same time at two, separate locations. Crudely assess for any increase in temperature on either side, , as this may suggest an underlying inflammatory process such as septic arthritis, or reactive arthritis.

The locations at which you palpate are not of huge importance. Simply identify two points, such as above and at the level of the patella.

Septic arthritis is joint inflammation due to infection, most commonly by bacteria such as staphylococci, streptococci or Neisseria gonorrhoeae. The joint will be warm, painful and swollen, with the patient often having a fever. The joint pain can be so severe that the patient is unwilling to move it.



Reactive arthritis is a sterile joint inflammation which occurs due to a bacterial infection taking place elsewhere in the body. The infection will result in cross-reactivity resulting in a warm, painful and swollen joint. Often there will be multiple extra-articular features such as conjunctivitis or urethritis which are also due to cross-reactivity.

Joint palpation

During this part of the examination, remind the patient to report if they feel any pain. Ask the patient to flex their knees to 90o, and then palpate each knee in turn, starting with the “good” knee.

Joint line

Palpate medially to laterally along the joint line, carefully palpating the medial and lateral collateral ligaments. Tenderness in the joint line is very sensitive for injury to the menisci or the ligaments.

Patella

Next, starting superiorly, palpate the quadriceps tendon, the patella and the patellar ligament. Tenderness at any point may be due to numerous pathologies such as patellar tendinitis, prepatellar bursitis, plica syndrome or patellofemoral pain syndrome.

Move back to the patella and gently move it medially and laterally whilst watching the patient’s face for apprehension. If the patient suddenly reacts, by exclaiming, wincing or reflexively contracting their quadriceps, this suggests patella sublaxation, dislocation or patellar tracking disorder.

This last action is sometimes referred to as the “patellar apprehension test.”

Patellar tracking may also be identified by palpating the patella during flexion and/or extension.

Patellar tendinitis: Also known as jumper’s knee, patellar tendinitis is an overuse injury common in jumping sports such as basketball. There will be an insidious onset of pain, usually after activity.

Prepatellar bursitis: This is inflammation of the prepatellar bursa, most commonly caused by single or multiple traumatic instances affecting the knee. There will be marked swelling anterior to the patella in addition to knee tenderness.

Plica syndrome: A synovial plica is a piece of mesenchymal tissue present just posterior to the patella. It is normally resorbed during embryological development, but in a large number of individuals it remains, and is at risk of inflammation following trauma or repetitive movement of the joint. This is known as plica syndrome and will present with and swelling.

Patellofemoral pain syndrome: Also known as runner’s knee, patellofemoral pain syndrome occurs when there is increased pressure on the patellofemoral joint. This may be due to sport, such as running, muscle imbalances, malalignment of the patella or a combination of these. The patient will have , usually on activity, and joint crepitus.

Osgood-Schlatter disease: In Osgood-Schlatter disease there is inflammation of the patellar ligament at the tibial tuberosity. The disease most commonly affects males in their teenage years and can be precipitated by sports or overuse. The patient will present with knee pain which may be mild or severe depending on the level of inflammation.

Tibial tuberosity and popliteal fossa

Continue distally and palpate the tibial tuberosity. Tenderness here is common in Osgood-Schlatter disease.

Finally, palpate in the popliteal fossa for a popliteal cyst.

Testing for effusion

Ask the patient to extend their knees to 180o again.

Patellar tap test

The patellar tap test assesses for an effusion. Keep the knees extended and glide your hand down the patient’s thigh to squash the suprapatellar pouch. This pushes an effusion, if present, out of the pouch and behind the patella. Utilising two fingers of the other hand press downwards gently on the patella itself. In the absence of an effusion, there will be minimal movement before the patella comes in to contact with the femur. If an effusion is present however, the patella will bounce or tap, and the test will be positive.

Fluid displacement test (bulge/sweep/stroke test)

In the absence of an apparent patellar tap, a fluid displacement test should be performed to identify an effusion in the medial or lateral compartment. Stroke the medial aspect of the knee upwards, milking the fluid proximally into the suprapatellar pouch, and keep your hand in this position. This will empty the medial compartment. Next, using the other hand, milk the fluid laterally and then downwards into the lateral compartment. If the medial side refills, this is a positive indicator that an effusion is present.

Range of movement

Active movement

Test the active range of movement of each knee, remembering to start with the “good” knee.

Passive movement

Following this, passively move each knee joint individually with one hand, attempting to elicit maximum flexion and extension. Whilst doing so, palpate the knee joint with the other hand to feel for crepitus. Crepitus is common in the elderly and can be entirely normal. It may however be a symptom of osteoarthritis, especially if there is associated knee pain.

Special tests

Cruciate ligaments

Perform the following tests on each knee, starting with the “good” knee.

Posterior sag

Flex each knee by approximately 90o. Ask the patient to relax and observe each leg for any posterior movement of the tibia relative to the femur, this is known as a “posterior sag,” and suggests rupture (a tear) of the posterior cruciate ligament.

It is important to identify if a posterior sag if present, as it can lead to a false positive sign in the anterior drawer test.

Anterior drawer test

Place your thumbs on the lateral aspects of the tibial tuberosity and your fingers in the popliteal fossa. Rest your forearms on the patients shin and gently pull the tibia towards you, feeling for any anterior movement relative to the femur. A tiny amount of movement is normal, but pronounced anterior movement suggests laxity or rupture of the anterior cruciate ligament.

Resting your forearms on the patient’s shin allows you to operate your forearm as a lever, one that is anchored to the distal aspect of the patient’s leg.

If you find the above technique difficult you may alternatively wish to lightly sit on the patient’s legs, and then simply grip the tibial tuberosity as described above, without needing to worry about leverage.

Posterior drawer test

Keeping your hands and forearms in the same position, this time push the tibia away from you, feeling for any posterior movement relative to the femur. Again, a tiny amount of movement is normal, but pronounced posterior movement suggests laxity or rupture of the posterior cruciate ligament.

Lachman test (optional)

The Lachman test is an optional alternative test that tests for laxity or rupture of the anterior cruciate ligament.

Flex each knee to 30o. Using your dominant hand, hold on to the patient’s calf with one hand, keeping your thumb on the tibial tuberosity. Use the other hand to hold the distal thigh, keeping it in place. Using your dominant hand, pull the tibia towards you. Pronounced anterior movement suggests laxity or rupture of the anterior cruciate ligament.

The cruciate ligaments of the knee consist of the posterior and anterior cruciate ligaments. Their function is to stabilise the knee preventing anteroposterior displacement of the tibia relative to the femur. They are frequently injured in sporting injuries.

The origins of the cruciate ligaments of the knee can be remembered by the mnemonic “PMAL.” The PCL originates from the medial femoral condyle and the ACL originates from the lateral femoral condyle.

Collateral ligaments

From complete extension, flex the patient’s “good” knee by approximately 30o and hold the ankle in place in your axilla. If you are assessing the patient’s right knee first, hold their right ankle in your right axilla, and vice-versa if assessing the left knee first.

Perform the varus and valgus stress test on that knee.

Both of the collateral ligaments can be tested with the patient’s ankle nested in the same axilla. Do not drop the ankle or swap its position between tests.

Varus stress test

Apply a varus stress on the knee to assess the integrity of the lateral collateral ligament. The directions to do this will be described for the right knee, where the patient’s right ankle will be nested in your right axilla. When testing the left knee, simply switch the positions of your hands:

  1. 1. Place your right hand such that the base of your palm is on the medial aspect of the knee.
  2. 2. Place your left hand a little lower on the lateral side, such that the palm is on the lateral calf, and the fingers are palpating the lateral collateral ligament.
  3. 3. Apply an outwards force using your right hand and an inwards force with the left, continuing to palpate the ligament whilst doing so.
  4. 4. Assess for any pain or gapping of the tibia away from the femur. If either are present, this suggests lateral instability.
“Gapping” will feel like an opening of the joint line. If present, there is instability on that side, suggesting laxity or injury of the corresponding collateral ligament.

Your hands should not be bearing the weight of the limb. This is the role of your axilla which should be tightly gripping the ankle.

Valgus stress test

Apply a valgus stress on the knee to assess the integrity of the medial collateral ligament. Again, the directions to do this will be described for the right knee, where the patient’s right ankle will be nested in your right axilla. When testing the left knee, simply switch the positions of your hands:

  1. 1. Place your left hand such that the base of your palm is on the lateral aspect of the knee.
  2. 2. Place your right hand a little lower on the medial side, such that the palm is on the medial calf, and the fingers are palpating the medial collateral ligament.
  3. 3. Apply an inwards force using your left hand and an outwards force with the right, continuing to palpate the ligament whilst doing so.
  4. 4. Assess for any pain or gapping of the tibia away from the femur. If either are present, this suggests medial instability.

The lateral and medial collateral ligaments connect the femur to the tibia providing lateral and medial stability respectively. They are most commonly injured due to trauma and will present with pain, swelling and instability on the corresponding side of the knee.

The lateral collateral ligament is most commonly injured by a blow to the inside of the knee pushing it outwards, whereas the medial collateral ligament is injured by a blow to the outside of the knee, pushing it inwards.

Repetition on the opposing side

Relax the “good” knee back on the bed in full extension. Passively flex the patient’s “bad” knee by approximately 30o and hold the ankle in place in your corresponding axilla (for example, left ankle in your left axilla). Repeat varus and valgus stress tests to assess the collateral ligaments on that knee.

For all ligament assessments, you may find that there is a natural degree of laxity. This is why you always test the “good” knee first, so you can compare to what is normal.

Menisci

Actively flex the “good” knee to full flexion. Then perform the McMurray test twice to assess the lateral and medial menisci.

The following tests can cause large amounts of pain and discomfort, so in an OSCE scenario, offer to perform the tests before actually doing so.

McMurray test – Lateral meniscus

Perform McMurray test to assess the integrity of the lateral meniscus. The directions to do this will be described for the right knee. When testing the left knee, simply switch the position of your hands.

  1. 1. Hold the (right) ankle with your right hand.
  2. 2. Place your left hand on the knee, with your thumb on the medial aspect and your fingers palpating the lateral joint line.
  3. 3. Using your left hand, apply a slow outwards force on the knee, thus applying a varus stress. Ensure that your fingers are still palpating the joint line.
  4. 4. Simultaneously with step 3, using your right hand, slowly internally rotate the leg whilst extending the limb at the knee joint.
  5. 5. If there is pain or you feel a “click” on the lateral joint line, this is a positive finding, and suggests a tear in the lateral meniscus.
Recall that the anatomical leg is the area between the knee and the ankle.

You are effectively positioning the lower limb into the cross-legged position, whilst internally rotating the leg at the same time.

McMurray test – Medial meniscus

After testing the integrity of the lateral meniscus, flex the knee back to the starting position of full flexion and perform McMurray test once again to assess the integrity of the medial meniscus. You do not need to reposition your hands.

The directions to do this will be described for the right knee. When testing the left knee, simply switch the position of your hands.

  1. 1. Continue to hold the (right) ankle with your right hand.
  2. 2. Place your left hand on the knee, with your thumb palpating the medial joint line and your fingers on the lateral aspect.
  3. 3. Using your left hand, apply a slow inwards force on the knee, thus applying a valgus stress. Ensure that your thumb is still palpating the joint line.
  4. 4. Simultaneously with step 3, using your right hand, slowly externally rotate the leg whilst extending the limb at the knee joint.
  5. 5. If there is pain or you feel a “click” on the medial joint line, this is a positive finding, and suggests a tear in the medial meniscus.
Note that you do not need to swap hands when testing each meniscus. However, if you are unable to effectively palpate the joint line with your thumb alone, you may feel free to do so.

The menisci of the knee are two pieces of cartilage which provide cushioning between the femoral condyles and the tibia. They can be ruptured during due to trauma causing a sudden twisting of the knee. Risk factors include osteoarthritis and age.

The patient will present with pain, swelling and knee instability, commonly with the feeling that your knee is about to “give way”.

Repetition on the opposing side

Relax the “good” knee back on the bed in full extension. Perform the McMurray test twice on the other knee to assess the lateral and medial menisci.

Remember to use opposing hands so that the procedure is easier to perform.

An alternative to the McMurray test is the Apley grind test. This is a more sensitive test but requires the patient to be prone.

Completion

Conclude your examination and offer to help the patient get dressed. Wash your hands. Offer to take a full history, examine the hip and ankle, look at any old radiographs and assess the neurovascular status of each lower limb.

Interactive markscheme


When assessing each other, please click on each list item as you go along. Doing so will turn the list item green. Make careful note of any steps missed at the end.
We recommend completing any examination or procedure in under 10 minutes, but you can adjust the timer to suit your needs.
:

  1. Introduction: “Hello, I’m SimpleOSCE and I am a medical student. I've been asked to examine your knee today, would that be ok? Can I confirm your name and DOB? Thank you.”
  2. "For the purpose of this examination the examiner will act as a chaperone."
  3. Ask if the patient is in any pain and identify which is their “good” and “bad” knee.
  4. Wash your hands.
  5. For all steps, where appropriate, examine the “good” knee first.
  6. Assess the patient’s body habitus and inspect around the bed for any paraphernalia.
  7. Inspection ("look")

  8. Ask the patient to walk 5m and assess gait.
  9. With the patient standing, inspect all sides of the knees for deformities, asymmetry, muscle wasting, swellings or scars (DAWSS).
  10. Ask the patient to lie down on the bed and extend their legs. Continue your inspection and look for patellar tracking.
  11. Measure the girth of the quadriceps femoris muscles.
  12. Palpation ("feel")

  13. Using the back of your hands, crudely assess the temperature of each knee.
  14. Bend the knee to 90o and palpate the joint line.
  15. Palpate the quadriceps femoris tendon, the patella, the patellar ligament, the tibial tuberosity and the popliteal fossa.
  16. Conduct the patellar tap and fluid displacement tests to check for an effusion.
  17. Movement ("move")

  18. Assess active knee flexion and extension.
  19. Assess passive flexion and extension whilst carefully palpating for crepitus.
  20. Special tests ("test")

  21. Bend the patient's knee and observe for posterior sag.
  22. Perform the anterior drawer test or Lachman’s test to assess the anterior cruciate ligament.
  23. Perform the posterior drawer test to assess the posterior cruciate ligament.
  24. Test for collateral ligament stability by performing the varus and valgus stress tests.
  25. Offer to perform the McMurray test on each knee.
  26. Thank the patient and ask if they need help getting dressed. Wash your hands again.
  27. "To complete my assessment I would like to examine the hip and ankle joints, look at any old knee radiographs and assess the neurovascular status of each lower limb."
  28. Present findings.
  29. Patient manner: Enquire about pain at all appropriate points of the examination.
Overall: 0/28