EXAMINATION OF THE KNEE


PRELIMINARY STUFF

  • The exam will be limited in cases of acute injury or inflammation
  • Examine the good knee (one without complaints) first, you're less likely to miss stuff
  • Encourage the pt to be precise about the location of the pain-In the knee, the perceived location usually corresponds to the location of the problem
  • Pain from complete tears of knee ligaments may be much less than with incomplete tears
  • In cases of injury, the mechanism suggests what's been damaged (see below)

  • I. Examination of skin-Abrasions may indicate direction of traumatic forces & also possibility of infection

    II. Gait
  • Abductor lurch-Pelvis drops on side where foot is in the air, opposite side of weakened gluteal muscles (indicates involvement of hip, e.g. fx or deformity of femoral neck or sup. gluteal nerve dysfunction)
  • If abductor lurch is present, then do Trendelenburg test (stand behind pt while s/he raises one leg; Pelvis drop on other side is a positive test)
  • Knee thrust-View from in front, look for medial or lateral buckling of the knee on heel strike. Indicates erosion of medial (with lat. buckling) or lat (with medial buckling) articular cartilages from osteoarthritis
  • III. Deep knee bend
  • Note at what degree of flexion pain occurs and whether it occurs on the way down, the way up, or both.
  • Pain at the bottom of the knee bend suggests tear of posterior horn or either meniscus
  • Pain on rising but not on the way down suggests a patellar origin of the pain
  • IV. Muscular contours & tone--thigh and calf

    V. Hip Exam for range of motion (hip pain can be referred to knee)

    VI. Vascular exam (foot pulses)-knee pain can represent intermittent claudication.

    VII. LE neurologic exam-To look for signs of spinal/nerve root problem

    VIII. The knee exam proper
    1. Inspection
      1. Note any asymmetry including of musculature
      2. Note any mass/swelling
        1. If present, note any signs of inflammation
        2. Swelling right anterior to patella = prepatellar bursa
        3. Diffuse swelling with loss of contours (e.g. hollows med & lat to patella) suggests fluid in joint space--see below for tests for this
      3. If patellae face outward, suggests instability or fem. neck anteversion
      4. Note "Q angle" (between quadriceps and patellar tendons)-Should be 15-20'
    2. Range of motion (active and passive)
      1. Crepitus on passive ROM testing suggests OA
      2. Flexion
        1. Normal maximum flexion is about 150'
        2. Test with pt supine; flex hip and knee simultaneously
        3. Deficit of passive flexion can be from to either intrinsic or extrinsic causes, e.g. effusion, femur fx
        4. Pain on complete flexion (passive) is usually from patellofemoral articulation
      3. "Extensor lag" = can't actively extend fully but full ROM with passive extension-Suggests rupture or tear of extensor tendons
      4. Check for recurvatum (hyperextension) on passive extension by holding pt's heels above level of table with pt. supine. Up to 20' is nl if bilat. Any unilat. recurvatum is abnormal (suggests ACL tear, especially if accompanied by noticeable extern. rotation of tibia)
      5. Causes of reduced passive extension ROM:
        1. Hamstring contracture
        2. Joint effusion
        3. Adhesions from previous injury, e.g. of cruciate ligament
        4. Meniscal tear (torn bit stuck between articular surfaces)
        5. Patellar pain syndromes
        6. If present, do "bounce test": With pt. supine hold heel in palm of hand above level of table; bounce it upward causing knee to flex and then abruptly jerk it upward, extending the knee. A normal knee will snap suddenly but painlessly into extension. A + bounce test is a soft stop--the knee slides softly into not-quite-full extension, often with pain. Suggests meniscal tear but can be other loose body in joint space sometimes seen with effusion.
    1. Palpation and other maneuvers
      1. Palpate for tenderness: Patella, retinaculum, quadriceps and infrapatellar tendons, tibial tubercule (Osgood-Schlatter's)
      2. Check patellar side-side mobility with knee extended; should be about 2cm each way (if reduced, suggests patellofemoral OA or adhesions; if increased, suggests instability)
      3. Joint margins (between femoral condyles and tibial plateau)
        1. Best examined at 90' flexion;
        2. Firm, compressible swellings in a pt > 50 yrs may represent menisceal cysts which occur as part of degeneration of the meniscii
        3. Tenderness truly in the joint line may represent a tear of either a meniscus or a coronary ligament (which hold the meniscii to the tibia laterally)
      1. The collateral ligaments
        1. Palpate their points of attachment for tenderness; Ligamental sprains usually present with well-localized pain and tenderness.
        2. Apply valgus/varus stress on knee and observe for pain-Do it with knee in 30' flexion because at full ext., ACL/PCL help support the knee against varus & valgus stresses
      2. The meniscii
        1. Joint line tenderness can suggest menisceal injury
        2. McMurray's test-Sensitivity 52% and specificity of 97%-With patient supine and knee and hip flexed to 45', place one hand on patient's ankle and one on the knee.  Proceed as below; an audible or palpated "click" is a positive sign for injury to the corresponding meniscus
          1. With patient supine and knee and hip flexed to 45', place one hand on patient's ankle and one on the knee.  Proceed as below; an audible or palpated "click" is a positive sign for injury to the corresponding meniscus
          2. To test the medial meniscus, apply valgus stress, externally rotate the tibia, and slowly extend the knee.
          3. To test the lateral  meniscus, apply varus stress, internally rotate the tibia, and slowly extend the knee.
        3. Thessaly test-Sensitivity and specificity of 90% and 95% respectively
          1. With patient standing, grasp pt's hands and instructs pt to stand on affected leg with foot flat on floor and flex unaffected knee to 45', then internally & externally rotate the affected knee three times.  Patient report of pain, or sensation of locking or clicking, is a positive test.
      3. The cruciate ligaments
        1. Anterior drawer test (place anterior shearing force on tibia and see if it moves forward--nl is <5mm excursion; more suggests ACL tear) In addition to excusion, look for obliteration of usual sulcusbelow the patella, and feel for the "endpoint"--sudden jolt when ligament becomes taut and excursion ceases. Lack of endpoint is the most specific clinical test for ACL tear. n.b. with a PCL tear can get a false + anterior drawer test because the initial position of the tibia is recessed and you're pulling it into normal anatomic position. Checking for the endpoint avoids this pitfall.
          Lachman's test--an anterior drawer test with the knee in 30' flexion instead of 90' flexion--more sensitive
          Posterior drawer test (place posterior shearing force on tibia--analagous to anterior; tests for PCL tear)
          Pivot shift test--pt. supine, 30' flexion; apply valgus strain and slowly extend knee; a shift suggests ACL damage
      4. Bursae--prepatellar (housemaid's), infrapatellar (Madonna's), semimembranosus (just inf. to the posteriomedial joint line--this is common), pes anserinus (a conjoint tendon of 3 hamstring muscles; the bursa is on med. side of the knee, inferior to joint line), iliotibial tract bursa (at lateral femoral condyle)
      5. Popliteus tendon--insertion is at lat. fem. condyle; sprain is suggested by tenderness here, pain worse with internal tibial rotation, and pain running downhill)
      6. Synovial reflection--on femoral condyles. Check for thickening which may indicate an inflammatory arthropathy
      7. Test for joint effusion
        1. Balottement of patella--milk suprapatellar bursa proximal-to-distal, then place 2 fingers on patella and press downward sharply, feeling for "tap" or patella on femur, which suggests joint effusion
      8. Popliteal fossa--Examine wiht patient  in prone position; check for masses and tenderness e.g. Baker's cyst, aneurysm, or tumor
    (Sources include Core Content Review of Family Medicine, 2012)