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Knee examination

Introduction

  • Wash hands
  • Introduce self
  • Ask Patientโ€™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: look for limp and movement restriction; assess knee movements during different phases of gait; check for normal heel-strike/toe-off
  • Standing inspection: alignment (patella/legs), varus/valgus deformities, fixed flexion deformity, recurvatum (hyperextension), popliteal swelling (e.g. Bakerโ€™s cyst, popliteal aneurysm)
  • Supine close inspection: skin (scars/arthroscopic portals, bruising, erythema, psoriatic plaques), joints (swelling, effusions), alignment (patella, tibia), position (fixed flexion deformity), โ€˜knobbly kneesโ€™ (osteoarthritis)
  • Measure quadriceps muscle bulk: measure quadriceps diameter 20 cm above tibial tuberosity; compare with contralateral side
Valgus and varus

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 patientโ€™s knee to 90หš (and look for tibial lag), then feel along joint line (quadriceps tendon โ†’ patella โ†’ patella tendon โ†’ tibial tuberosity โ†’ tibial plateau โ†’ femoral epicondyles and over course of medial collateral ligament and lateral collateral ligament โ†’ popliteal fossa). Note any swelling, synovial thickening and tenderness.
  • Effusion tests โ€“ test with knee extended

Cross fluctuation test

  • Empty suprapatellar pouch by applying pressure with one hand
  • Hold your other hand just below the patella and alternate compressions each side
  • Positive test = impulses transmitted from side to side (large effusion)

Patella tap test

  • Empty suprapatellar pouch, then sharply tap patella with index finger
  • Positive test = patella sinks, striking femur, then comes back up (moderate effusion)

Bulge 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 = ripples on medial surface (small effusion)

Move

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

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

Special tests

Collateral ligaments

Hold the patientโ€™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 0หš and 30หš of knee flexion. (You can hold their foot between your elbow and your side.) Look/feel for excessive movement (collateral ligament laxity).

Drawer test

First check for foot pain, then flex knee to 90หš, sit on the side of their foot, and hold upper tibia with thumbs on tibial tuberosity and fingers in popliteal fossa. Pull anteriorly (anterior lag = anterior cruciate ligament laxity); then push posteriorly (posterior lag = posterior cruciate ligament laxity).

Lachmanโ€™s test

With the patientโ€™s knee flexed to 30หš, 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).

McMurrayโ€™s test

Warn patient this test may cause pain. Flex knee as much as possible. 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).

Patellofemoral apprehension test

Flex knee while pressing patella laterally. If patella is unstable, patient will anticipate dislocation and stop you.

Apleyโ€™s grind test

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

Grading knee ligament injuries

โ€ข Grade 1: pain but knee stable

โ€ข Grade 2: pain and laxity 

โ€ข Grade 3: very lax (no end point)

Function

  • Squat test

To complete

  • Thank patient and restore clothing
  • โ€˜To complete my examination, I would examine the hips and the ankles, and perform a distal neurovascular examination.โ€™
  • 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!

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