Knee examination

Question 1

Special tests in knee examination?

Answer 1

Posterior sag sign (PCL)
Anterior draw test (ACL)
Posterior draw test (PCL)
Valgus stress test (MCL)
Varus stress test (LCL)
McMurrays test

Question 2

What does posterior sag sign indicated?

Answer 2

The posterior cruciate ligament (PCL) is 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 3

How to perform posterior sag sign test?

Answer 3

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.

Question 4

What test must be performed before the anterior draw test and why?

Answer 4

Posterior sag test

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 5

What is the anterior draw test and how is it performed?

Answer 5

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 6

What is the posterior drawer test and how is it perfromed/?

Answer 6

The posterior drawer test is used to assess the integrity of the posterior 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. 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 7

How to perform varus stress test + findings?

Answer 7

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 8

How to perform valgus stress test + findings?

Answer 8

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 9

How to perform McMurray’s test (right knee)?

Answer 9

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. - testing for medial meniscus tare

5, 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. - testing for lateral meniscus tare

The presence of a click and discomfort in 4/5 is suggestive of a meniscal tear.

Question 10

Completion of knee examination?

Answer 10

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).

Question 11

LOOK section of knee examiantion?

Answer 11

Obeseve gait cycle -
Front: quadriceps bulk, knee swelling and deformity, foot swelling
Side: knee flexion, foot arches, toe deformity
Behind: Gluteal muscle bulk, popliteal swellings, hindfoot abnormalities

Question 12

FEEL section of knee examination

Answer 12

Joint temp
Palpation with leg straight: quadriceps tendone, patella and boarders, patella tendon
Patella tap - large effusions
Patella swipe - small effusions
Palpation with knee flexed: patella tendon, tibial tuberosity, medial joint lines, lateral joint lines, head of fibula, collateral ligamanets, popliteal fossa
MEASURE AND COMPARE QUADRICEPS TENDONS

Question 13

Active movements in the knee o/e?

Answer 13

Active flexion and extension - compare both knees

Question 14

Normal range ove movement of flexion and extension of the knee?

Answer 14

0-140 degrees

Question 15

Passive movements of the knee on examination ?

Answer 15

Flex and extend while feeling for creptis

Hyperextension (lift foot)

Question 16

How far should the knee be able to hypextend passively?

Answer 16

Less than ten degrees

Question 17

What is a valgus deformity of the knee?

Answer 17

the tibia is turned outward in relation to the femur, resulting in the knees ‘knocking’ together

Question 18

What is a varus deformity of the knee?

Answer 18

The tibia is turned inward in relation to the femur, resulting in a bowlegged appearance.

Question 19

What might cause quadriceps wasting?

Answer 19

Disuse atrophy or a lower motor neuron lesion.

Question 20

What might hyperextension of the knee suggest?

Answer 20

Cruciate ligament injury

Question 21

What might fixed flexion deformity at the knee joint suggest?

Answer 21

Fixed flexion deformity at the knee joint may suggest the presence of contractures secondary to previous trauma, inflammatory conditions or neurological disease.

Question 22

Causes of popliteal swelling?

Answer 22

Bakers cyst

Popliteal aneurysm

Question 23

What should be observed when the patient is walking?

Answer 23

Cycle - toe-off, heel strike
Range of movement
Limping - pain, weakness, joint instability
Leg length - discrepency might signify joint pathology
Height of steps - peroneal nerve palsy - high stepping gait (foot drop)

Question 24

Where should you measure quadricep muscle circumfrance?

Answer 24

Aprox 20cm above the tibial tuberosity

Question 25

Causes of joint effusion?

Answer 25

Ligament rupture (ACL)
Septic arthritis
Inflammatory arthritis
OA

Question 26

WHat is bony elevation and tenderness of the tibial tuberosity associated with?

Answer 26

Osgood-Schlatter disease

Question 27

Clinical features of knee OA?

Answer 27

Pain, may radiate to thigh and hip, exacerbated by exercise and relived by rest
Bilateral disease
Associated joint stifness - reduced ROM
Joint swelling in severe cases
Crepitus in severe cases
Eveidence of muscle wasting
Reduced ROM

Question 28

Management of OA of knee?

Answer 28

Conservative: weigh loss, ex, smoking cessation, analgesia, physio
Surgical: if conservative not enough - TKR or unicondylar knee replacement

Question 29

Special clinical features of patellofemoral osteoarthritis?

Answer 29

Anterior knee pain

Worse with activites putting pressure on the patellar such as climing stairs

Question 30

Diagnosis of knee OA?

Answer 30

Plain film radiograph:

- Lateral, AP, (Skyline for patellar involvement)

Question 31

Clinical features of ACL injury?

Answer 31

Unable to weight bear
Rapid joint swelling
Significant pain
Instablilty
Positive anterior draw test (following negative posterior sag)

Question 32

Management of ACL tare?

Answer 32

Conservative treatment involves rehabilitation, which utilises strength training of the quadriceps to stabilise the knee
In the emergency setting, inpatient admission is rarely required; the patient can often partially weight bear and a cricket pad knee splint can be applied for comfort.
Surgical reconstruction of the ACL involves the use of a tendon or an artificial graft
This is not performed acutely but following a period of ‘prehabilitation’, whereby the patient will engage with a physiotherapist for a period of months prior to the surgery

Question 33

Investigation of ACL tare?

Answer 33

A plain film radiograph of the knee (AP and lateral) should be taken to exclude bony injuries, any joint effusion, or a lipohaemarthrosis present. A Segond fracture (bony avulsion of the lateral proximal tibia) is pathognomic of ACL injury.

An MRI scan of the knee is gold-standard to confirm the diagnosis (>90% sensitivity), also picking up any associated meniscal tears*

Question 34

MCL tare clinical features?

Answer 34

Medial joint line pain
Swelling
Increased laxity in valgus stress test

Question 35

Investigating MCL tare?

Answer 35

Any patient following trauma with significant knee pain and swelling should have a plain film radiograph to exclude any fracture.

The gold-standard investigation to confirm the diagnosis for an MCL tear is via MRI scanning, delineating the exact extent and grade of the tear.

Question 36

Management of MCL tear?

Answer 36

Grade I Injury: Rest, Ice, Compression, and Elevation (RICE) with analgesia (typically NSAIDs) as the mainstay. Strength training as tolerated should be incorporated, with an aim to return to full exercise within around 6 weeks.
Grade II Injury: Analgesia with a knee brace and weight-bearing/strength training as tolerated. Patients should aim to be able to return to full exercise within around 10 weeks
Grade III Injury: Analgesia with a knee brace and crutches, however any associated distal avulsion then surgery is considered. Patients should aim to be able to return to full exercise within around 12 weeks.

Question 37

How to perform Lachman’s test?

Answer 37

Lachman’s test involves placing the knee in 30 degrees of flexion and, with one hand stabilising the femur, pulling the tibia forward to assess the amount of anterior movement of the tibia compared to the femur. The other knee is then examined for comparison.