Knee Exam

Knee Examination


 

Introduction

Careful examination of the knee can provide valuable information and help the physician determine when imaging studies may or may not be helpful.

Technique

  • Inspection: Observe both knees together. Note any asymmetry of the joint or quadriceps muscles.
  • Ask patient to lie supine. Whenever possible, ensure patient can lie comfortably with head back, legs straight, and toes up
  • Assess temperature by placing back of hand to shin then ipsilateral knee, repeated for both legs.
    • Commonly, the knee will feel cooler than the shin.
    • If knee feels warmer than shin, suspect inflammation.
    • Try the "crossover test" with one hand on one knee and one on the other knee. Decide if there's a temperature difference. Next, cross the hands to test the opposite knee. If there's a temperature difference, it will be exagerated by this maneuver.
  • Assess for fluid
    • Method 1: Gently press just medial of the patella, then move the hand in an ascending motion. Then press firmly on the lateral aspect of the knee.
      • Commonly, no fluid will be appreciated.
      • A medial aspect that 'bulges' out after lateral pressure (positive "bulge sign") is consistent with a moderate amount of fluid.
      • A medial aspect that does not bulge but tensely reflects lateral pressure is consistent with a large amount of fluid.
    • Method 2: Assess for fluid by placing one hand superior to the patella and with slight downward pressure milk the suprapatellar pouch which emptys into the knee joint. Next use the other hand to push to push on the patella. If there is an effusion, the patellar will bounce off the underlying bone (patella tap test).
      • A palpated or audible tap indicates a "ballotable" knee and is consistent with at least a moderate amount of fluid.
  • Assess for tendon pathology by firmly palpating the superior pole of the patella and then the inferior to assess patellar femoral syndrome.
    • Tenderness at the superior insertion is consistent with quadriceps tendon pathology.
    • Tenderness at the inferior insertion is consistent with patellar tendonitis, "Jumpers knee."
      • In the patient with direct patellar trauma & isolated patellar tenderness, an x-ray is indicated to evaluate for fracture.
  • Assess for cartilage pathology
    • Apley's grind test (patellar cartilage tear): By placing palm on patella and applying firm pressure while manipulating the patella in the sagittal plane. Crepitus is significant only when accompanied by tenderness, in which case it is consistent with patellar cartilage pathology.
    • McMurray test (meniscus cartilage tear):
      • Lateral meniscus tear: With patient supine, fully flex the knee, place forefingers on lateral side of joint line, then with applying valgus stress and internal rotation of leg, extend the knee looking for both pop/click and pain
      • Medial meniscus tear: With patient supine, fully flex the knee, place forefingers on medial side of joint line, then with applying varus stress and external rotation of leg, extend the knee looking for both pop/click and pain
  • Assess for laxity
    • While supine, ask patent to flex knee and set foot on examination table. Sit on the foot to immobilize it and grasp the head of the tibia with both hands and pull anteriorly.
      • Movement greater than 1cm (positive anterior drawer sign) is consistent with an anterior cruciate ligament (ACL) tear.
      • Do not attempt to elicit an anterior drawer sign with legs hanging; the extra degree of freedom will confound any findings.
      • Lachman test: flex the knee only 20-30 degrees (rather than 90 degrees in anterior drawer sign), then attempt to pull tibia anterior relative to the femur. If positive, a deficient ACL will demonstrate increase movement forward. This test is thought to be more sensitive than the anterior drawer sign.
    • Attempt to hyperextend knee by placing one hand superior to the patella and the other posterior to the heel. More than 2-3cm (i.e. able to place one or two fingers beneath the heel when leg is extended and flat) is abnormal.
    • With both hands, flex and extend the knee. Repeat while introducing medial and lateral rotation. Determine if any "locking" or "catching" is present.
    • With leg straight, apply valgus stress and varus stress to text deviation greater than a few centimeters.

Consult the Expert

Mark Genovese

Dr. Mark Genovese is certified in rheumatology and is actively involved in house staff training at Stanford University. He is involved in research including clinical trials and interventions in rheumatic diseases such as rheumatoid arthritis, psoriatic arthritis, & osteoarthritis.

Clinical Pearl

If a careful exam does not elicit significant pain or laxity, imaging studies are extremely unlikely to provide further useful information.