II. Risk Factors

  1. Femal gender
  2. Older age
    1. Affects one third of those over age 65 years
  3. Obesity (Body Mass Index >30 mg/kg)
  4. Occupation
    1. Prolonged squatting or kneeling
    2. Lifting more than 25 kg regularly
    3. Walking more than 2 miles per day
  5. History of comorbid inflammatory joint disease
    1. Septic Knee Joint
    2. Gouty Arthritis
    3. Rheumatoid Arthritis
  6. Previous Knee Injury (e.g. Meniscal tear)

III. Symptoms: General

  1. Less than 30 minutes of morning knee stiffness resolving with activity
  2. Chronic progressive Knee Pain
  3. Mild Joint Swelling
  4. Crepitation on knee range of motion
  5. Provocative
    1. Standing or weight bearing
    2. Stair climbing
  6. Palliative
    1. Rest
  7. Findings suggestive of advanced cases
    1. Instability symptoms
    2. Genu Valgum (knock knee)
    3. Genu Varum (bow leg)
      1. More common due to medial meniscus more often affected

IV. Signs

  1. Mild Knee Effusion
  2. Minimal synovial thickening
  3. Atrophy of Muscles surrounding knee
  4. Restricted knee range of motion (active and passive)

VI. Diagnosis

  1. Clinical criteria
    1. Age over 50 years
    2. Bony enlargement
    3. Bony tenderness
    4. Crepitation
    5. No palpable warmth
    6. Stiffness less than 30 minutes
  2. Lab criteria
    1. Erythrocyte Sedimentation Rate (ESR) <40 mm/h
    2. Rheumatoid Factor <1:40
    3. Synovial Fluid clear, viscous with white count <2000 per uL
  3. Imaging criteria
    1. Osteophytes present
  4. Interpretation
    1. Knee Pain and 3 clinical criteria
      1. Test Sensitivity: 95%
      2. Test Specificity: 69%
    2. Knee Pain and either lab criteria or 5 clinical criteria
      1. Test Sensitivity: 92%
      2. Test Specificity: 75%
    3. Knee Pain and osteophytes on xray and either lab criteria or 5 clinical criteria
      1. Test Sensitivity: 91%
      2. Test Specificity: 86%
  5. References
    1. Altman (1986) Arthritis Rheum 33:1039-49 [PubMed]
    2. Wu (2005) Semin Arthritis Rheum 35(3): 197-201 [PubMed]

VII. Labs

  1. Synovial Fluid examination
    1. Indication: Nontraumatic monarticular effusion
    2. Findings
      1. White Blood Cells <200 per mm3 (<2000 in a flare)
      2. Fluid color is clear and minimally turbid
  2. Rheumatologic evaluation
    1. See Osteoarthritis

VIII. Radiology: Knee XRay

IX. Management

X. Management: Referral Indications

  1. Systemic Rheumatic disease
  2. Significant functional deterioration
  3. Septic Arthritis or Osteomyelitis
  4. Primary malignancy or metastases
  5. Safety concerns (e.g. recurrent falls)
  6. Pain and Disability refractory to conservative care

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Related Studies

Ontology: Osteoarthritis, Knee (C0409959)

Definition (MSH) Noninflammatory degenerative disease of the knee joint consisting of three large categories: conditions that block normal synchronous movement, conditions that produce abnormal pathways of motion, and conditions that cause stress concentration resulting in changes to articular cartilage. (Crenshaw, Campbell's Operative Orthopaedics, 8th ed, p2019)
Concepts Disease or Syndrome (T047)
MSH D020370
ICD10 M17 , M17.9
SnomedCT 239873007, 201893003, 156493004, 201908002, 239856005
English Knee osteoarthritis NOS, Osteoarthritis NOS, of knee, Osteoarthritis, Knee, Knee Osteoarthritides, Knee Osteoarthritis, Osteoarthritides, Knee, osteoarthrosis of knee, osteoarthritis of knee (diagnosis), osteoarthritis of knee, osteoarthrosis of knee (diagnosis), OSTEOARTHRITIS SUSCEPTIBILITY 6, OS6, OSTEOARTHRITIS OF KNEE, Osteoarthritis of knee, unspecified, Osteoarthritis, Knee [Disease/Finding], knee osteoarthritis, Osteoarthritis;knee, knee osteoarthrosis, Gonarthrosis, Knees, Osteoarthritis Of, Knee, Osteoarthritis Of, Osteoarthritis Of Knee, Osteoarthritis Of Knees, Osteoarthritis NOS, of knee (disorder), OA - Osteoarthritis of knee, Osteoarthritis of knee, Degenerative joint disease of knee, Knee DJD, Osteoarthritis of knee (disorder), Osteoarthrosis of knee, Osteo arthritis knees, OA knee, Knee osteoarthritis, Osteoarthritis knee, Osteoarthritis knees, osteoarthritis of the knee
Dutch knie osteoartritis, osteoartritis knie, osteoartritis nek, osteoartritis knieën, Gonartrose, Gonarthrosis, Artrose van de knie, Knieartrose, Osteoarthritis van de knie
French Arthrose des genoux, A du genou, Ostéoarthrite des genoux, Gonarthrose, Arthrose du genou
German Osteoarthritis des Knies, Osteoarthritis Knie, OA Knie, Gonarthrose, Arthrose, Knie, Osteoarthrose, Knie
Italian Osteoartrite delle ginocchia, Osteoartrite de ginocchio, Gonartrosi, Osteoartrite del ginocchio
Portuguese Osteartrite do joelho, Osteartrite dos joelhos, Osteoartrite do Joelho
Spanish Osteoartritis de las rodillas, Artrosis de rodilla, OA de rodilla, Artrosis de rodillas, Osteoarthritis NOS, of knee, artrosis, SAI, de rodilla (trastorno), artrosis, SAI, de rodilla, artrosis de la rodilla (trastorno), artrosis de la rodilla, artrosis rotuliana, Osteoartritis de la Rodilla
Swedish Knäartros
Czech gonartróza, osteoartritida kolenní, Osteoartritida kolene, Osteoartritida kolen
Finnish Polviartroosi
Japanese ヘンケイセイヒザカンセツショウ, ヒザカンセツOA, ヘンケイセイシツカンセツショウ, 変形性膝関節症, 膝関節OA, シツカンセツOA
Polish Choroba zwyrodnieniowa stawu kolanowego
Hungarian Térdízületi arthrosis, Térdek arthrosisa, Térd arthrosis, Térd OA
Norwegian Kneartrose, Kneleddsartrose, Artrose i kneet, Degenerativ knelidelse