Examination of the Knee Joint
- Introduce yourself to the patient
- Wash your hands
- Briefly explain to the patient what the examination involves
- Ask the patient to remove their bottom clothing, exposing the entire knee
- Offer the patient a chaperone, as necessary
Always start with inspection and proceed as below unless instructed otherwise; be prepared to be instructed to move on quickly to certain sections by the examiner.
Whilst the patient is standing:
- Assess patient gait. Common gaits include:
- Antalgic: produced from weight bearing on painful leg. The stance-phase is shortened, producing the characteristic ‘limping’ patient.
- Trendelenberg: weakness of the hip abductors (gluteus medius + minimus). This is general examination finding, rather than a sign of knee pathology.
- Assess symmetry and for deformity
- Level of patellae bilaterally
- Genu varum (or bowlegged), where the tibia is angulated medially in relation to the femur
- Genu valgum (or knock-kneed), where the tibia is angulated laterally in relation to the femur
- Assess quadriceps muscle bulk
- These waste rapidly (within weeks) in knee disease
Ask the patient to lie supine on the bed
- Assess for:
- Skin changes (e.g. erythema from septic arthritis)
- Scars (e.g. previous arthroplasty or arthroscopy)
- Swellings, including joint effusions, inflamed bursa (typically pre-patellar and infra-patella bursae), parameniscal cysts, or Baker’s cysts
- Assess temperature, comparing both sides
- Start at the mid-thigh and work to the mid-shin
- Palpate the extensor mechanism:
- Start with quadriceps muscle and quadriceps tendon, feel around the patella and the patella ligament, and then press over the tibial tuberosity
- Check for a joint effusion
Assessing for Joint Effusion
Two methods can be used to assess for joint effusion in the knee:
- The Sweep Test – Milk the suprapatella pouch, keeping the hand firmly pressed on the distal thigh, to ensure all fluid is pushed and retained within the knee joint. Use the other hand to concurrently ‘sweep’ away fluid from the medial gutter. With the initial hand still in place, ‘sweep’ the lateral gutter from distal to proximal, and whilst doing this, look closely at the medial gutter – if you see a bulge, this indicates a small joint effusion
- The Patella Tap Test – As above, empty the suprapatellar pouch, and with the other hand, press firmly down an the patient’s patella. You will feel its undersurface ‘tapping’ against the trochlea of the distal femur. This is a crude test for a large joint effusion, although these can also be apparent on inspection.
- Palpate the origin and insertion of the MCL and LCL
- Palpate the menisci
- Flex the knee to 90 degrees and palpate across the medial and lateral joint lines
- Palpate the popliteal fossa:
- With the knee still flexed, palpate for masses posterior to the knee, such as Baker’s cysts or popliteal aneurysms
- Straight leg raise*
- Place your hand around 30cm off the bed and ask the patient to kick it, keeping their leg straight, demonstrating the integrity of the extensor mechanism
- Check for hyperextension (most knees extend to ~5 degrees beyond neutral)
- Place your fist under the patients heel and ask them to push their knee in to the couch
- Check range of flexion
- place your hand over their anterior knee and ask them to flex as far as they can, also noting any crepitus
*You will occasionally be faced with a patient that is in too much pain to perform this; in these cases, lift their leg a few centimetres from the bed and support their knee and foot, before letting go of their foot, whilst still supporting their knee, and ask them to keep their leg straight
Assess the stability of the knee ligaments:
- Assess the ACL:
- Lachmann’s Test*
- Flex the knee to 30 degrees. Place one hand on the distal femur and one hand on the proximal tibia. Firmly pull the tibia anteriorly, whilst stabilising the femur with the contralateral hand.
- Feeling for (i) laxity (that is greater than the contralateral side) and (ii) absence of a solid end point
- Anterior drawer test
- Flex the knee to 90 degrees and sit on the patient’s foot. With both hands, grasp the proximal tibia at the level of the tuberosity. Pull firmly anteriorly, also assessing for laxity and end point
*Lachmann’s test is seen as a more sensitive test to ACL disruption than the anterior draw test
- Assess the PCL:
- Posterior drawer test
- Flex the knee to 90 degrees and sit on the patient’s foot. With both hands, grasp the proximal tibia at the level of the tuberosity. Push firmly posteriorly, assessing for laxity and end point
- Assess the MCL and LCL, using the stress tests
- Flex the knee to 30 degrees and hold the ankle between your arm and torso
- Place hands on opposing sides of the knee and firmly push the knee in to (i) valgus stress and (ii) varus stress. Note pain and laxity with this manouvre.
N.B McMurray’s test is no longer recommended to assess meniscal damage
Complete the Examination
Thank the patient and allow them to redress. Remember, if you have forgotten something important, you can go back and complete this.
State to the examiner that to complete your examination you would also like to examine the joint above and below (hips and ankles), the contralateral knee, and reviewing any relevant imaging available.