Physical examination if knee pain

Physical examination:

• compare the painful knee with the asymptomatic knee (1)
  
  
• inspect the knee for any
  • deformities (fixed or reducible)
  • swellings (bony, articular, bursal or other soft tissue swelling)
  • muscle wasting
  • features of inflammation (erythema, warmth) (2)
    
    
• palpation may reveal effusion or tenderness
  • in case of an effusion
    • determine whether
  • the swelling is articular or extra articular
  • there are signs of infection or regional lymphadenopathy
  • there is any evidence of a poly-articular problem (2)
  • there is loss of the dimples either side of the patella
  • tenderness
    • joint line tenderness may be caused by meniscal tears (but is not pathognomonic for meniscal injury)
      • palpation of the anterior half of each meniscus can be improved by flexing the knee
      • palpation of the medial edge of the medial meniscus becomes easier with internal rotation of the tibia
      • palpation of the lateral meniscus is made easy by external rotation of the tibia (3)
        
        
• range of motion -
  • extend and flex the knee as far as possible - normal range is zero degrees in extension and 135 degrees in flexion (1)
    
    
• the following clinical tests (in the presence of an appropriate history) can be used to assess the injury to knee ligaments (4)
  • to detect anterior cruciate ligament (ACL) injury -
    • anterior drawer test
    • Lachman test
    • pivot shift test (best performed by an experienced practitioner) (4)
  • to detect posterior cruciate ligament (PCL) injury
    • posterior sag sign,
    • the posterior drawer test
    • the quadriceps active test
  • to detect medial collateral ligament (MCL) injuries - Valgus stress test
  • to detect lateral collateral ligament (LCL) injuries - Varus stress test (3)
    
    
• examine the hip joint
  • arthritis of the hip joint can result in referred pain to the knee (5)
• Other investigations:
  • X - ray
    • has a limited value in diagnosing acute non-traumatic knee pain
    • the necessity of x-ray for acute traumatic knee injury has been defined in the Ottawa knee rules (2). The rule states that the presence of any one or more of the following indicates for an X-ray of the knee to exclude a fracture:
      • aged 55 or older and/or
      • tenderness at the head of the fibula and/or
      • isolated tenderness of the patella and/or
      • inability to flex knee to 90 degrees and/or
      • inability to walk four weight-bearing steps at time of injury and at examination (4)
        
        
  • MRI - will provide information about soft tissue structures
    
    
  • FBC, ESR, CRP; uric acid if gout is suspected; blood and joint cultures - if infection is suspected (7)

Note:

• The Keele KNEST (knee pain screening tool) may be used as a reliable and valid tool in investigating the prevalence, severity and duration of knee pain and the use of health care related to knee pain in the community and primary care (6)

Reference:

• 1. Calmbach WL, Hutchens M. Evaluation of patients presenting with knee pain: Part I. History, physical examination, radiographs, and laboratory tests. Am Fam Physician. 2003;68(5):907-12.
• 2. Australian Acute Musculoskeletal Pain Guidelines Group 2003. Evidence-based management of acute musculoskeletal pain. Australian Government National Health and Medical Research Council
• 3. Malanga GA et al. Physical examination of the knee: a review of the original test description and scientific validity of common orthopedic tests. Arch Phys Med Rehabil. 2003;84(4):592-603
• 4. New Zealand Guidelines Group (NZGG) 2003. The diagnosis and management of soft tissue knee injuries: internal derangements. Best practice evidence-based guideline
• 5. Felson DT. Clinical practice. Osteoarthritis of the knee. N Engl J Med. 2006;354(8):841-8.
• 6. Jinks C et al. A brief screening tool for knee pain in primary care. 1. Validity and reliability. Rheumatology (Oxford). 200;40(5):528-36.
• 7. Houghton KM. Review for the generalist: evaluation of anterior knee pain. Pediatr Rheumatol Online J. 2007;5:8.