Examination of the Knee

Question 1

How do we begin a knee examination?

Answer 1

When examining the knee, the patient should be wearing their underpants/shorts but should
remove their trousers, socks and shoes. Ensure that upper thigh is exposed so that you can
examine the quadriceps
• Wash your hands
• Introduction, identification and consent

Question 2

What are the key stages of the knee examination?

Answer 2

Inspection, 
Palpation, 
Move (assessing range of motion),
  Special tests,
 function, 
and completion

Question 3

What is involved in the inspection stage of the knee examination?

Answer 3

• With the patient standing, inspect from the front, side and behind for:
o Valgus deformity (knock-knees)
o Varus deformity (bow-legs)
o Genu recurvatum (knee hyperextension)
o Flexion deformity
o Swellings in the popliteal fossa e.g. Baker’s cyst
o Comment on the patient’s stance

• Position the patient supine on the couch with their hips and knees extended. Inspect
for:
o Symmetry
o Valgus and varus deformity
o Rashes e.g. psoriasis
o Scars
o Swelling, particularly in the medial fossa (the depression medial to the patella)
o Muscle wasting, particularly in the medial quadriceps (vastus medialis)
o Displacement of the patella
o Fixed-flexion deformity

Question 4

What is involved in the palpation (feel) stage of the knee examination?

Answer 4

• Assess the temperature using the dorsum of your hand in the mid-thigh, over the
patella and over the upper tibia. Normally the patellar region feels cooler than the
surrounding tissues. Compare both sides.
• Palpate around the borders of the patella for tenderness
• Palpate behind the knee for popliteal swellings or cysts
• Assess for an effusion by performing:
o The bulge test (cross-fluctuation): This test is particularly sensitive in picking
up a small effusion. Sweep the hand firmly up the medial fossa, over the
suprapatellar pouch and down the lateral fossa. The medial fossa may refill,
producing a bulge of fluid; and/or
o The patellar tap: With one hand, compress the suprapatellar pouch to empty it. Use 2 or 3 fingers of the other hand to ‘bounce’ the patella against the femur.
• Flex the knee up to 90° to open the joint line. Palpate the joint line and patellar tendon insertion (tibial tuberosity) for tenderness.

Question 5

How do we assess the range of motion in the knee?

Answer 5

Ask the patient to actively flex and extend his knee (normal range of flexion = 135°,
normal range of extension = 0°).
• Assess passive movement by placing one hand on the patient’s knee and flexing the
knee as far as possible with your other hand.
• Palpate for crepitus during passive flexion and extension.

Question 6

What are the special tests for the knee exam?

Answer 6

Posterior Sag test: Position the patient with the knee flexed to 90° and the foot flat on the bed. Inspect from the side. A posterior sag of the upper tibia, with a ‘step’ visible below the patellar, is suggestive of posterior cruciate ligament (PCL) damage.
• Anterior draw test: Position the patient with the knee flexed to 90° and the foot flat on the bed. Stabilise the leg using your own forearm – for infection control reasons you should not sit on the patient’s bed. With the fingers of both hands behind the knee and the patients hamstrings relaxed, place your thumbs over the tibial tuberosity and apply a forward pull. Significant movement indicates a positive draw test and suggests anterior cruciate ligament (ACL) damage.
• Lateral collateral ligament test: Flex the knee to 20°. Grasp the patient’s heel with one hand while exerting pressure against the inside of the knee with the other hand. The varus stress applied will cause lateral gaping in the laterally unstable knee. A small amount of lateral joint gaping is physiological and is the asymmetry of the gaping that constitutes the abnormal finding.
• Medial collateral ligament test: As above but apply a valgus stress against the lateral
aspect of the knee and assess for medial gaping.

Question 7

How do we assess function in the knee exam?

Answer 7

Ask the patient to walk. Observe the toeing angle. (This is the angle between the orientation of the foot and the direction the patient is walking. Normally the axis will be seen to point in a slightly lateral direction by 10-15°)
• Is there an antalgic (painful) gait? Is there any other abnormality?
Note: If you prefer, gait may be assessed at the beginning of the examination along
with stance

Question 8

How do we complete the knee exam?

Answer 8

Examine the ipsilateral hip and ankle. When examining the ankle, you should use the schema ‘look, feel, move’.
• Assess the neurological and vascular status of the limb (In the OSCE, unless you are given specific instructions to perform this assessment, you should simply state to the examiner that you would do so).
• Thank the patient and request them to redress
• Wash your hands

Question 9

What other tests should we consider in the Knee exam?

Answer 9

Lachman’s test: This test has higher sensitivity and specificity than the anterior draw test for detecting ACL laxity. However, the REMS national curriculum specifies that the anterior draw should be taught to medical students (1). Many orthopaedic surgeons will ask you to perform the Lachman’s test instead and in the OSCE, you may perform either test, depending on your personal preference. Flex the knee to 20°. Place one hand behind the tibia with your thumb on the tibial tuberosity. Grasp the patient’s thigh with your other hand and pull anteriorly on the tibia. You should feel a firm end-point as the anterior cruciate ligament (ACL) prevents forward translocation of the tibia on the femur. A soft end-point suggests ACL damage. If the patient’s thigh is too large, or your hand is too small, to stabilise the limb adequately, you may perform Lachman’s test with the patient’s thigh supported by the edge of the examination couch.

McMurray’s test: The test is designed to trap or catch a torn meniscus between the femoral condyle and the tibial plateau and should only be performed if the patient’s history is suggestive of a torn meniscus (In the OSCE, if you need to perform this test, you will be instructed to do so). Flex the patient’s hip to 90° and maximally flex the knee. Externally rotate the knee and, maintaining this rotation, move the knee gradually from the fully flexed position to the fully extended position. The test is repeated using internal rotation. A palpable, audible, or painful click over the medial or lateral joint line indicates a meniscal tear. The test is useful when positive but is unreliable when negative. It is difficult to perform on an acutely painful knee.