Knee Special Tests

Question 1

Lachmann’s test

Answer 1

Lachman’s test is an alternative test assessing for laxity or rupture of the anterior cruciate ligament (ACL).

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 2

Patella Tap Test

Answer 2

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 3

Patella Sweep Test

Answer 3

Can be 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 4

Anterior Draw Test

Answer 4

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 5

Posterior Draw test

Answer 5

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 6

Varus Stress Test

Answer 6

The 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 7

Valgus Stress Test

Answer 7

The medial collateral ligament (MCL) assessment involves the application of a valgus force to assess the integrity of the MCL 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 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 8

McMurrays Test (medial Meniscus)

Answer 8

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 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 9

McMurrays Test (Lateral Meniscus)

Answer 9

McMurray’s test for assessing the lateral meniscus
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.