Knee examination

Table of Contents

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: 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. Baker’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), ‘knobbly knees’ (osteoarthritis)
Measure quadriceps muscle bulk: measure quadriceps diameter 20 cm 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

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

Special tests

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).

First check for foot pain, then flex knee to 90˚, 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).

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).

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).

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

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