Examination of the Knee Joint

Original Author: Mike Bath
Last Updated: September 23, 2016
Revisions: 7

Introduction

  • 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.


Inspection

Whilst the patient is standing

  • Assess patient gait
    • Antalgic gait produced from weight bearing on painful leg, shortening the stance phase on the affected limb
  • 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 muscle bulk
    • Quadriceps muscle wastes rapidly in joint disease

Ask the patient to lie supine on the bed

  • Assess for scars, swellings, and skin changes

Palpation

  • Assess temperature, comparing both sides
    • Start at mid-thigh and work to mid shin
  • Check for joint swelling
    • Patellar tap assesses for large effusions.
      • Extend the knee and empty the suprapatellar pouch by pushing down from above the knee
      • Tap over the patella for any signs of effusion
    • Bulge test assesses for smaller effusion if no response from the patellar tap
      • Stroke the medial side upwards to empty the medial compartment then stroke the lateral side downwards
      • Any effusion present will cause the medial compartment to refill
  • Feel for tenderness around the knee
    • Start with quadriceps muscle and quadriceps tendon
    • Feel around the patella and the patella ligament
    • Press over the tibial tuberosity
    • Flex the knee to 90 degrees and palpate across the medial and lateral joint line, feel for pain over medial and lateral collateral ligaments
    • Feel in the popliteal fossa for swellings/masses (e.g. Baker’s cyst, popliteal artery aneurysms)

Movement

  • Straight leg raise, checking for continuity of the extensor mechanism (quadriceps muscles, quadriceps tendon, patella and patella tendon)
    • An inability to straight leg raise may represent pathology of part of the mechanism (e.g. quadriceps tendon rupture)
  • Assess passive movement, checking for crepitus, pain, and range of movement
    • Flexion and extension
  • Assess active movement, assessing muscle strength
    • Flexion and extension against resistance

Special Tests

Assess the stability of the knee ligaments

  • Anterior and posterior drawer test, assessing for the ACL and PCL respectively
    • Flex the knee to 90 degrees
    • Pull the tibia anteriorly in relation to the femur for anterior drawer test
    • Push the tibia posteriorly in relation to the femur for posterior drawer test
      • Normal for both is movement of a cm or two with a firm end point, excess laxity or lack of an end point may indicate ACL/PCL rupture respectively (always compare to the contralateral side)
  • Lachman’s test can be used as a more specific test for the ACL
    • Flex the knee to 30 degrees and cradle the calf and lower leg in one hand taking the weight of the leg
    • With the other hand push gently down on the thigh whilst pulling up the lower leg with the other hand
  • Varus and Valgus stress tests will assess the collateral ligaments
    • Flex the knee to 30 degrees and hold the ankle between your arm and torso
    • Place hands on opposing sides of the knee, pushing and pulling to test laxity

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.

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