Knee

Question 1

What is the general layout of the knee exam

Answer 1

WIPERQQ
Look (inspection and gait)
Feel
Move
Special tests
Conclusion, summary, and further tests

Question 2

What do you look for in the general inspection during the knee exam

Answer 2

body habitus, scars, wasting
objects: aids etc

closer knee inspection with patient standing and turn in 90 degree increments
- Anterior: bruising, swelling, psoriasis plaques, patella position, varus/valgus deformity, quadriceps deformity

• Lateral: extension/flexion abnormalities
• Posterior: wasting, scars, popliteal swelling

Then observe gait and then knee when patient is lying down

Question 3

What is important to check when looking for swelling of the knees

Answer 3

symmetry - evidence of asymmetry in the size of the knee joints may suggest unilateral swelling (e.g. effusion, inflammatory arthropathy, septic arthritis, haemarthrosis).

Question 4

What are the valgus and varus knee deformities

Answer 4

Valgus deformity of the knee: the tibia is turned outward in relation to the femur, resulting in the knees ‘knocking’ together.

Varus deformity of the knee: the tibia is turned inward in relation to the femur, resulting in a bowlegged appearance.

Question 5

What can cause extension abnormalities?

Flexion?

Answer 5

Extension abnormalities: knee hyperextension can occur secondary to cruciate ligament injury.

Flexion abnormalities: fixed flexion deformity at the knee joint may suggest the presence of contractures secondary to previous trauma, inflammatory conditions or neurological disease

Question 6

Give 2 possible causes of a swelling on the posterior aspect of the knee

Answer 6

Popliteal swellings: possible causes include a Baker’s cyst or popliteal aneurysm (typically pulsatile).

Question 7

What should you look for in the knee exam when assessing gait

Answer 7

Gait cycle
Range of movement
Limp
Leg length
Turning
Height of steps (high-stepping gait is associated with foot drop, which can be caused by peroneal nerve palsy (e.g. trauma, surgery).)

Question 8

What are the phases of the gait cycle

Answer 8

The gait cycle has six phases:

• Heel-strike: initial contact of the heel with the floor.
• Foot flat: weight is transferred onto this leg.
• Mid-stance: the weight is aligned and balanced on this leg.
• Heel-off: the heel lifts off the floor as the foot rises but the toes remain in contact with the floor.
• Toe-off: as the foot continues to rise the toes lift off the floor.
• Swing: the foot swings forward and comes back into contact with the floor with a heel strike (and the gait cycle repeats).

Question 9

What do you assess in the Feel section of the knee exam (5)

Answer 9

Temp
Quads bulk
Palpation of extended knee
Palpation of flexed knee
Assess for joint effusion

Question 10

How do you assess quadriceps bulk in the knee exam?

Why do you do this

Answer 10

To measure the circumference of the leg in the region of the quadriceps place a measuring tape around each leg at a point approximately 20cm above the tibial tuberosity.

Quadriceps wasting is commonly associated with knee joint pathology occurring secondary to disuse atrophy. Wasting will often be apparent on inspection, however subtle wasting may only be detectable by comparative measurement of leg circumference.

Question 11

How do you palpate the extended knee in the knee exam

Answer 11

With the patient’s leg straight and relaxed, systematically palpate the joint lines and surrounding structures of each knee joint.

1. Patella
2. Medial and lateral joint lines

Question 12

How do you assess the patella in the extended knee

Answer 12

1. Assess the medial and lateral border of the patella for tenderness by stabilising one side of the patella and palpating the other with a fingertip:

Tenderness may represent injury or patellofemoral arthritis.
If the patient appears apprehensive, developing tension in the muscles of the leg as you begin to mobilise the patella (typically in the lateral direction), it may suggest a history of recurrent patellar dislocation which the patient is anticipating (this can be formally assessed using the patellar apprehension test).

2. Palpate the patellar ligament for tenderness suggestive of tendonitis or rupture

Question 13

How do you assess the knee’s medial and lateral joint lines

Answer 13

1. Palpate the medial and lateral joint lines of the knee including the collateral ligaments for evidence of tenderness which may suggest:
   - Fracture
   - Meniscal injury (e.g. meniscal tear)
   - Collateral ligament injury (e.g. rupture)
2. Palpate the quadriceps tendon for tenderness suggestive of tendonitis or rupture.

Question 14

How would you perform the patella apprehension test?

(The patellar apprehension test is not usually performed in an OSCE, but it’s useful to understand how the test is carried out.)

Answer 14

With the patient’s knee fully extended lateral pressure is applied to the patella whilst simultaneously slowly flexing the knee joint. The presence of active resistance from the patient is suggestive of previous patellar instability and dislocation (as the patient is apprehensive about it recurring).

Question 15

What can cause joint effusion (4)

Answer 15

Ligament rupture (e.g. anterior cruciate ligament),
septic arthritis,
inflammatory arthritis
osteoarthritis.

Question 16

What does the patella tap test for?

How is it performed?

Answer 16

The patellar tap test can be used to screen for the presence of a moderate-to-large knee joint effusion.

1. With the patient’s knee fully extended, empty the suprapatellar pouch by sliding your left hand down the thigh to the upper border of the patella.
2. Keep your left hand in position and use your right hand to press downwards on the patella with your fingertips.
3. If there is fluid present you will feel a distinct tap as the patella bumps against the femur.

Question 17

How do you assess for joint effusion in the knee exam

Answer 17

Patella tap
Sweep test

Question 18

What is the sweep test and how do you perform it

Answer 18

useful to identify small joint effusions that may not be obvious using the patellar tap method.

1. Position the patient supine with the leg relaxed and knee extended.
2. Empty the suprapatellar pouch by sliding your left hand down the thigh to the upper border of the patella.
3. Stroke the medial side of the knee joint to move any excess fluid across to the lateral side of the joint.
4. Now stroke the lateral side of the knee joint which will cause any excess fluid to move back across to the emptied medial side of the knee joint. This causes the appearance of a bulge or ripple on the medial side of the joint indicating the presence of effusion.

Question 19

What do you assess when feeling the flexed knee in the knee exam

Answer 19

Patella
Medial and lateral joint lines
Tibial tuberosity and head of fibula
Popliteal fossa

Question 20

What are you assessing for in the knee exam when you assess the medial and lateral joint lines

Answer 20

Palpate the medial and lateral joint lines of the knee including the collateral ligaments for evidence of tenderness which may suggest:

Fracture
Meniscal injury (e.g. meniscal tear)
Collateral ligament injury (e.g. rupture)

Question 21

What are you assessing when you feeling the tibial tuberosity and head of fibula in the knee exam

Answer 21

Palpate the tibial tuberosity (can easily be palpated as the protrusion located just inferior to the patella) for evidence of a bony elevation and tenderness which is typically associated with Osgood-Schlatter disease.

Palpate the head of the fibula for tenderness which is often associated with fracture.

Question 22

What is the function of the tibial tuberosity

Answer 22

Attachment site for the patellar ligament

Question 23

How do you assess the popliteal fossa in the feel part of the knee exam

Answer 23

With your thumbs placed on the tibial tuberosity, curl your fingers into the popliteal fossa and palpate for evidence of a swelling which may indicate the presence of a popliteal cyst (often referred to as a Baker’s cyst). A pulsatile mass in the popliteal fossa may represent a popliteal aneurysm.

Question 24

What is a key pathology you should be aware of when assessing the tibial tuberosity?

Give the epidemiology , presentation, and risk factors

Answer 24

Osgood-Schlatter disease (OSD)

involves inflammation of the patellar ligament at the tibial tuberosity (its insertion point) and most often affects males between the age of 10-15.

Typical presenting features include a painful bony elevation over the tibial tuberosity which is worsened with activity.

Risk factors include overuse, often due to sports that involve lots of running and jumping.

Question 25

What active knee actions should the patient do in the knee exam?

Give normal range of movement and associated instructions

Answer 25

Active knee flexion
Normal range of movement: 0-140°

Instructions: Ask the patient to flex their knee as far as they are comfortably able to – “Move your heel as close to your bottom as you can manage.”

Active knee extension
Normal range of movement: the leg should be able to lie flat (180°)

Instructions: Ask the patient to extend their knee, so that their leg is flat on the bed – “Straighten your leg out so that it is flat on the bed.”

Question 26

How do you assess passive knee flexion

Answer 26

Instructions: Whilst supporting the patient’s leg, flex the knee as far as you are able, making sure to observe for signs of discomfort.

(Normal range of movement: 0-140°)

Question 27

How do you assess passive knee extension

Answer 27

f the patient is able to lay their legs flat on the bed, they are already demonstrating a normal range of movement for knee extension. To assess for hyperextension:

1. On the leg being assessed, hold above the ankle joint and gently lift the leg upwards.
2. Inspect the knee joint for evidence of hyperextension, with less than 10° being considered normal. Excessive knee hyperextension may suggest pathology affecting the integrity of the knee joint’s ligaments.

Question 28

What are the special tests you should do in the knee exam (7)

Answer 28

Cruciate ligament assessment (posterior sag sign, anterior/posterior drawer test, Lachman’s)

Collateral ligament assessment (varus and valgus stress tests)

Menisci (McMurray’s tests)

Question 29

What does the posterior cruciate ligament do

Answer 29

responsible for preventing backward displacement of the tibia or forward sliding of the femur. As a result, if the PCL is ruptured the tibia can sag posteriorly in relation to the femur and this is what is known as the ‘posterior sag sign’.

Question 30

How can you screen for the posterior sag sign

Why is it important to do this first

Answer 30

To screen for the posterior sag sign make sure the patient is relaxed and ask them to flex their knee to 90º with their foot placed flat on the bed. Inspect the lateral aspect of the knee joint for evidence of posterior sag.

It is important to identify this sign before proceeding to the anterior drawer test, as a posterior cruciate ligament tear can result in a false positive anterior drawer sign. This is because an anterior movement of the tibia will occur during the anterior drawer test due to the tibia moving from a posteriorly subluxed position back to its neutral position. This relocation of the tibia to its neutral position may then be misinterpreted as excessive anterior movement secondary to anterior cruciate ligament laxity or rupture.

Question 31

Describe the anterior drawer test (6 steps)

Answer 31

The anterior drawer test is used to assess the integrity of the anterior cruciate ligament.

1. Position the patient supine on the clinical examination couch with their knee flexed to 90º.
2. Wrap your hands around the proximal tibia with your fingers around the back of the knee joint.
3. Rest your forearm down the patient’s lower leg to fix its position.
4. Position your thumbs over the tibial tuberosity.
5. Ask the patient to keep their legs as relaxed as tense hamstrings can mask pathology.
6. Pull the tibia anteriorly and feel for any anterior movement of the tibia on the femur. With healthy cruciate ligaments, there should be little or no movement noted. Significant movement may suggest anterior cruciate ligament laxity or rupture.

Question 32

Describe the posterior drawer test (6)

Answer 32

1. Position the patient supine on the clinical examination couch with their knee flexed to 90º.
2. Wrap your hands around the proximal tibia with your fingers around the back of the knee joint.
3. Rest your forearm down the patient’s lower leg to fix its position.
4. Position your thumbs over the tibial tuberosity.
5. Ask the patient to keep their legs as relaxed as tense hamstrings can mask pathology.
6. push the tibia posteriorly. With healthy cruciate ligaments, there should be little or no movement noted. Significant posterior movement may suggest posterior cruciate ligament laxity or rupture.

Question 33

What is Lachman’s test

Answer 33

Lachman’s test is an alternative test assessing for laxity or rupture of the anterior cruciate ligament (ACL). This test is rarely required in an OSCE scenario, with the anterior drawer test being the preferred method of ACL assessment.

Question 34

How do you perform Lachman’s test

Answer 34

1. Flex the patient’s knee to 30°.
2. Hold the lower leg with your dominant hand with your thumb on the tibial tuberosity and your fingers over the calf.
3. With the non-dominant hand, hold the thigh just above the patella.
4. Use the dominant hand to pull the tibia forwards on the femur while the other hand stabilises the femur.

Significant anterior movement of the tibia on the femur suggests ACL laxity or rupture.

Question 35

What is the origin and insertion of the ACL

What is its primary purpose

Answer 35

ACL originates from deep within the notch of the distal femur and inserts in the anterior region of the intercondylar area of the tibia.

Its primary purpose is to stabilise the knee joint by preventing anterior tibial subluxation (i.e. prevent anterior displacement of the tibia relative to the femur)

Question 36

What is the origin and insertion of the PCL

What is its primary purpose

Answer 36

PCL originates from the lateral edge of the medial femoral condyle and attaches in the posterior region of the intercondylar area.

Its primary purpose is to stabilise the knee joint by preventing posterior tibial subluxation (i.e. prevent posterior displacement of the tibia relative to the femur).

Question 37

Describe a typical mode of injury to ACL and PCL

Answer 37

ACL injury (i.e. rupture) typically occurs when a patient lands on a leg and then quickly pivots in the opposite direction resulting in a valgus twisting injury (e.g. in football).

PCL injury typically occurs secondary to hyperflexion of the knee joint (e.g. a fall onto a flexed knee).

Question 38

What is the varus stress test

Describe (6 steps)

What are possible results

Answer 38

AKA lateral collateral ligament (LCL) assessment involves the application of a varus force to assess the integrity of the LCL of the knee joint.

The instructions below are for examining the right knee, use the opposite hands if assessing the left knee.

1. Extend the patient’s knee fully so that the leg is straight.
2. Hold the patient’s ankle between your right elbow and side.
3. Position your right palm over the medial aspect of the knee.
4. Position your left palm a little lower down over the lateral aspect of the lower limb, with your fingers reaching upwards to palpate the lateral knee joint line.
5. Push steadily outward with your right palm whilst pushing inwards with the left palm.
6. Whilst performing this manoeuvre, palpate the lateral knee joint line with the fingers of your left hand.

With healthy collateral ligaments, there should be no abduction or adduction possible.

If there is LCL laxity or rupture your fingers should be able to feel a palpable gap caused by the lateral aspect of the joint opening up secondary to the varus force being applied

Question 39

What is the valgus stress test

Describe (6 steps)

What are possible results

Answer 39

AKA medial collateral ligament (MCL) assessment

The instructions below are for examining the right knee, use the opposite hands if assessing the left knee.

1. Extend the patient’s knee fully so that the leg is straight.
2. Hold the patient’s ankle between your right elbow and side.
3. Position your left palm over the lateral aspect of the knee.
4. Position your right palm a little lower down over the medial aspect of the lower limb, with your fingers reaching upwards to palpate the medial knee joint line.
5. Push steadily inward with your left hand whilst pushing outwards with the right hand.
6. Whilst performing this manoeuvre, palpate the medial knee joint line with the fingers of your right hand.

With healthy collateral ligaments, there should be no abduction or adduction possible.

If there is MCL laxity or rupture your fingers should be able to feel a palpable gap caused by the medial aspect of the joint opening up secondary to the valgus force being applied.

Question 40

What are the special tests for collateral ligaments in the knee exam

Answer 40

valgus and varus stress tests

further collateral ligament assessment (If after varus/valgus stress tests the knee appears stable you can further assess the collateral ligaments by repeating this test with the knee flexed at 30°. At this position, the cruciate ligament is not taught so minor collateral ligament laxity can be more easily detected.

Question 41

How do you assess the menisci in the knee exam

Answer 41

McMurray’s test is used to assess the menisci for evidence of a meniscal tear. This test is not usually expected in an OSCE scenario as it can cause significant pain and even meniscal injury if performed incorrectly. It is important however to have an awareness of how and why the test is performed.

Question 42

How do you do McMurray’s test for the medial meniscus

Answer 42

1. With the patient supine on the clinical examination couch, passively flex the knee being assessed as far as is possible.
2. Hold the patient’s right knee with your left hand, with your thumb over the medial aspect and fingers over the lateral aspect of the joint lines.
3. Hold the patient’s right foot by the sole using your right hand.
4. Create valgus stress on the knee joint with your left hand by applying outward pressure as if trying to abduct the leg at the hip whilst fixating and externally rotating the foot. At the same time slowly extend the knee joint.

The presence of a click and discomfort is suggestive of a medial meniscal tear

Question 43

How do you do McMurray’s test for the lateral meniscus

Answer 43

The instructions below are for examining the right knee, use the opposite hands if assessing the left knee.

1. With the patient supine on the clinical examination couch, passively flex the knee being assessed as far as is possible.
2. Hold the patient’s right knee with your left hand, with your thumb over the medial aspect and fingers over the lateral aspect of the joint lines.
3. Hold the patient’s right foot by the sole using your right hand.
4. Create varus stress on the knee joint with your left hand by applying inward pressure as if trying to adduct the leg at the hip whilst fixating and internally rotating the foot. At the same time slowly extend the knee joint.

The presence of a click and discomfort is suggestive of a lateral meniscal tear.

Question 44

What are the menisci

How are they usually injured and how does this present

Answer 44

two crescent-shaped pads of fibrocartilagenous tissue which function to stabilise the knee joint and distribute friction between the femur and tibia.

Injury to the menisci can occur secondary to sudden twisting of the knee (e.g. in football) which tears the meniscal tissue.

Typically symptoms of meniscal injuries include sudden-onset pain, a popping sensation, locking and instability of the knee joint.

Question 45

What further assessments should you suggest at the end of the knee exam

Answer 45

Neurovascular examination of both lower limbs.
Examination of the joints above and below (e.g. ankle and hip).
Further imaging if indicated (e.g. X-ray and MRI).