Knee Exam

Knee Exam

General

  • Wash your hands upon entering the room
  • Introduce yourself and the exam to the patient in a way that the patient will understand
  • Patient should initially be standing for the gait examination. Afterwards, the patient should be supine on a flat bed
  • Drape the patient so both legs are exposed. Ensure that the groin remains draped

Vital Signs

Vital signs should be measured on every patient. They include:

  • Blood pressure
  • Heart rate
  • Respiratory rate
  • Temperature
  • Oxygen saturation may also be included

Gait Inspection

 A gait inspection should be conducted as part of the knee exam

  • With the patient standing still, inspect the legs for the following:
    • Valgus deformity (knock knees)
    • Varus deformity (bow legged)
    • Genu recurvatum (hyperextension of the tibiofemoral joint)
  • Ask the patient to walk to the end of the examining room and back. Examine for the following gait abnormalities:
    • Antalgic gait

Inspection

Ask the patient to lie supine on the examining table

Ensure that both legs remain exposed but the groin remains covered. Examine for the following - it is important to compare both knees for symmetry:

  • Patient's General Appearance
    • Does the patient appear to be in pain?
  • Masses, Scars, Lesions
    • Examine for evidence of trauma, previous knee surgery
  • Joint Swelling
    • Examine for swelling in the knee joint. Compare both sides
  • Erythema
    • Examine for areas of erythema
  • Muscle Atrophy/Hypertrophy
    • Examine the legs for evidence of atrophy/hypertrophy
  • Bony Abnormalities
  • Baker's Cyst
    • As the patient to stand, and examine the posterior aspect of the knee for evidence of a Baker's cyst.

Tests for Effusion

There are three techniques for detecting an effusion:

  • Bulge Sign (for small effusions)
    • Sweep one hand up the medial aspect of the knee to force fluid into the suprapatellar pouch
    • After pausing for a moment, sweep the hand down the lateral aspect of the joint, beginning at the suprapatellar pouch, and keeping the hand below the level of the patella
    • If fluid is present, the sweep downward will force fluid back into the joint space and will be seen as a buldge on the medial aspect of the joint. For this reason, keep your eyes focused on the medial aspect of the joint
    • Try to minimize the amount of soft tissue movement to prevent a "false positive" sign.
    • Caution: False negatives can occur with large effusions
  • Patellar Tap (for large effusions)
    • Apply pressure to the suprapatellar compartment
    • Press gently on the patella with your other hand
    • Positive test - hear a 'click' or feel the patella tap against the underlying femoral condyles
  • Ballottement (for large effusions)
    • Apply pressure to the suprapatellar compartment
    • Palpate the medial and lateral compartments with your thumb and index fingers of the other hand
    • Positive test - fluid can be felt by your fingers and can be shifted from the medial to the lateral compartment, and back

Palpation

Before palpating, ask the patient if they have any areas of tenderness. Take caution when palpating tender areas.

  • Temperature
    • Run your hands down the patient's leg, feeling for temperature
      • Normal - the knee is cooler than the rest of the leg
      • Abnormal - the knee is warm. This suggests inflammation
  • Joint Line Tenderness
    • Flex the patient's knee to 90o
    • Palpate the tibial tuberosity, then palpate superiorly along the patellar tendon to the joint line
    • Palpate down the joint line medially and laterally for tenderness

 

Range of Motion

There are two components to testing range of motion in the knee:

  • Active Range of Motion
    • Ask the patient to bring their heel to their buttock, then fully extend
    • Normal = 120o flexion, full extension
  • Passive Range of Motion
    • Grasping the patient's heel, passively flex and extend the patient's leg at the knee
    • As you flex and extend, palpate the kneecap and joint line for crepitus

Special Tests

There are special tests for the stability of the ligaments within the knee. They are as follows:

  • Anterior Drawer Test for the Anterior Cruciate Ligament (ACL)
    • Flex the patient's knee to 90o
    • Stabilize the patient's leg by pressing your forearm against the patient's tibia
    • Grasp the patient's leg below the knee and apply a posterior to anterior force
    • Positive test - the tibia displaces anteriorly

Figure: Posterior Drawer Technique (arrow represents direction of force)

  • Posterior Drawer Test for the Posterior Cruciate Ligament (PCL)
    • Flex the patient's knee to 90o
    • Stabilize the patient's leg by pressing your forearm against the patient's tibia
    • Grasp the patient's leg below the knee and apply an anterior to posterior force
    • Positive test - the tibia displaces posteriorly

Figure: Posterior Drawer Technique (arrow represents direction of force)

  • Test for Medial Collateral Ligament (MCL) Instability
    • Slightly flex the knee so it is not locked
    • Apply a valgus strain to the leg
    • Positive test - excessive valgus deformity upon application of strain

Figure: Test for MLC Instability (Arrow represents direction of force)

  • Test for Lateral Collateral Ligament (LCL) Instability
    • Slightly flex the knee so it is not locked
    • Apply a varus strain to the leg
    • Positive test - excessive varus deformity upon application of strain

Figure: Test for LCL Instability (Arrow represents direction of force)