Knee examination

Introduction

• Wash hands
• Introduce self
• Ask Patient’s name, DOB and what they like to be called
• Explain examination and obtain consent
• Expose to underwear/shorts
• General inspection: patient, e.g. age, pain/discomfort, signs of trauma; around bed, e.g. mobility aids, splint

Look

• Gait: speed, stability, gait cycle phases, limb position/movement

Inspect standing and lying:

• Deformities of joint/bones/alignment: varus/valgus deformities, fixed flexion deformity, patellar alignment, joints effusions, ‘knobbly knees’ (osteoarthritis)
• Skin: scars, sinuses, swellings, rashes (e.g. psoriatic plaques)
• Muscles: measure quadriceps circumference 20cm above tibial tuberosity; compare with contralateral side

Feel

Ask about any pain and then start by examining the normal side with the patient supine.

• Skin: palpate general area for temperature and soft tissue swelling/tenderness
• Joint: flex patient’s knee to 90˚ (and look for tibial lag), then feel along joint line (quadriceps tendon → patella → patella tendon → tibial tuberosity → tibial plateau → femoral epicondyles and over course of medial collateral ligament and lateral collateral ligament → popliteal fossa). Note any swelling, synovial thickening and tenderness.
• Effusion tests – test with knee extended

Patella tap test

• Empty suprapatellar pouch
• Tap patella with index and middle finger tips
• Positive test = patella taps femur then floats back up (moderate-large effusion)

Fluid displacement (stroke) test

• Empty suprapatellar pouch
• Then systematically stroke around the knee starting from the inferomedial position, up the medial side (drains medial compartment), then down the lateral side to end in the inferolateral position
• Positive test = visible bulge of fluid on medial surface (small effusion)

A patient presents to ED with chest pain and this trace. What would you do?

Interpretation management

Covered in OSCE Stations

Move

Test active then passive movements, keeping one hand on the knee to feel for crepitus.

• Flexion (140˚)
• Extension (0˚)
• Passively raise leg at ankle and look for knee hyperextension (up to 10˚ normal; greater in collagen disorder/ hypermobility)

Special tests

Collateral ligaments

Hold the patient’s ankle/lower leg in one hand and their knee in the other. Apply varus and valgus knee forces to the knee. This stresses lateral and medial collateral ligaments respectively. Test at 0˚ and 30˚ of knee flexion. (You can hold their foot between your elbow and your side.) Look/feel for excessive movement (collateral ligament laxity).

Drawer test

Flex knee to 90˚. With your hands around their upper tibia (thumbs on tibial plateau), pull anteriorly (anterior lag = anterior cruciate ligament laxity); then push posteriorly (posterior lag = posterior cruciate ligament laxity).

Lachman’s test

With the patient’s knee flexed to 30˚, hold one hand on top of their thigh and the other on their posteromedial proximal tibia. Pull tibia anteriorly (more sensitive for anterior cruciate ligament laxity).

McMurray’s test

Fully flex the patient’s knee. Use one hand to externally rotate their foot and hold it over to the contralateral side of the patient. Then apply varus force to knee with the other hand, while extending the knee joint (stresses medial meniscus). Then test the opposite side (stresses lateral meniscus). Positive test = painful click felt or heard (meniscal tear).

Apley’s grind test

With patient prone and knee flexed to 90˚, apply axial load to the knee and rotate foot (pain = meniscal damage)

Grading knee ligament injuries

• Grade 1: pain but knee stable

• Grade 2: pain and laxity 

• Grade 3: very lax (no end point)

Function

• Squat test

To complete

• Thank patient and restore clothing
• ‘To complete my examination, I would examine the hips and the ankles, and perform a distal neurovascular examination.’
• Summarise and suggest further investigations you would consider after a full history

Common knee pathology

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Viva questions

Please list some causes of a knee effusion

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The ‘unhappy triad’ also known as a ‘blown knee’ refers to which three injuries?

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A patient presents with a red, hot and swollen knee, what are your differentials?

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Anterior lag on the anterior drawer test would indicate which pathology?

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What is a bursa and how does a bursitis develop?

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Some OSCE stations

1. Normal knee exam
2. Osteoarthritis
3. More here!