Updated: 9/28/2018

Knee Osteoarthritis

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Review Topic
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Evidence
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Introduction
  • Definition degenerative disease of synovial joints that causes progressive loss of articular cartilage 
  • Epidemiology
    • incidence
      • hip OA (symptomatic)
        • 88 per 100,000 per year
      • knee OA (symptomatic)
        • 240 per 100,000 per year
  • Risk factors 
    • modifiable
      • articular trauma
      • occupation, repetitive knee bending
      • muscle weakness
      • large body mass
      • metabolic syndrome 
        • central (abdominal) obesity, dyslipidemia (high triglycerides and low-density lipoproteins), high blood pressure, and elevated fasting glucose levels.
    • non-modifiable
      • gender
        • females >males
      • increased age
      • genetics
      • race
        • African American males are the least likely to receive total joint replacement when compared to whites and Hispanics 
  • Pathophysiology
    • pathoanatomy 
      • articular cartilage 
        • increased water content
        • alterations in proteoglycans 
          • eventual decrease in amount of proteoglycans
        • collagen abnormalities 
          • organization and orientation are lost
        • binding of proteoglycans to hyaluronic acid
      • synovium and capsule
        • early phase of OA
          • mild inflammatory changes in synovium
        • middle phase of OA
          • moderate inflammatory changes of synovium
          • synovium becomes hypervascular
        • late phases of OA
          • synovium becomes increasingly thick and vascular
      • bone
        • subchondral bone attempts to remodel 
          • forming lytic lesion with sclerotic edges (different than bone cysts in RA)
        • bone cysts form in late stages
        • osteophytes form through the pathologic activation of endochondral ossification mediated by the Indian hedgehog (Ihh) signaling molecule 
  • Cell biology
    • proteolytic enzymes
      • matrix metalloproteases (MMPs)
        • responsible for cartilage matrix digestion
          • examples
            • stromelysin
            • plasmin
            • aggrecanase-1 (ADAMTS-4)
      • tissue inhibitors of MMPS (TIMPs)
        • control MMP activity preventing excessive degradation
        • imbalance between MMPs and TIMPs has been demonstrated in OA tissues
      • inflammatory cytokines
        • secreted by synoviocytes and increase MMP synthesis
          • examples
            • IL-1
            • IL-6
            • TNF-alpha
  • Genetics
    • inheritance
      • non-mendilian
    • genes potentially linked to OA
      • vitamin D receptor
      • estrogen receptor 1
      • inflammatory cytokines
        • IL-1
          • leads to catabolic effect
        • IL-4
        • matrilin-3
        • BMP-2, BMP-5
Classification
 
Kellgren & Lawrence (based on AP weightbearing XRs)
Grade 0
 • no joint space narrowing (JSN) or reactive changes
Grade 1
 • possible osteophytic lipping + doubtful JSN
Grade 2
 • definite osteophytes + possible JSN
Grade 3
 • moderate osteophytes + definite JSN + some sclerosis + possible bone end deformity
Grade 4
 • large osteophytes + marked JSN + severe sclerosis + definite bone end deformity
 
Presentation
  • History
    • identify age, functional activity, pattern of arthritic involvement, overall health and duration of symptoms
  • Symptoms
    • function-limiting knee pain 
      • effect on walking distances
    • pain at night or rest
    • activity induced swelling 
    • knee stiffness
    • mechanical 
      • instability, locking, catching sensation
  • Physical exam
    • inspection
      • body habitus
      • gait
        • often an increased adductor moment to the limb during gait 
      • limb alignment    
      • effusion
      • skin (e.g. scars)
    • range of motion
      • lack of full extension (>5 degrees flexion contracture)
      • lack of full flexion (flexion <110 degrees) 
    • ligament integrity 
Imaging
  • Radiographs
    • recommended views
      • weight-bearing views of affected joint 
    • optional views
      • knee
        • sunrise view  
        • PA view in 30 degrees of flexion  
    • findings
      • pattern of arthritic involvement
        • medial and/or lateral tibiofemoral, and/or patellofemoral
      • characteristics  
        • joint space narrowing 
        • osteophytes
        • eburnation of bone
        • subchondral sclerosis 
        • subchondral cysts
Studies
  • Histology 
    • loss of superficial chondrocytes
    • replication and breakdown of the tidemark
    • fissuring
    • cartilage destruction with eburnation of subchondral bone
Treatment
  • Nonoperative
    • non-steroidal anti-inflammatory drugs 
      • indications
        • first line treatment for all patients with symptomatic arthritis
      • technique
        • Non-steroidal anti-inflammatory drugs (first choice)
          • selection should be based on physician preference, patient acceptability and cost
          • duration of treatment based on effectiveness, side-effects and past medical history
      • outcomes
        • AAOS guidelines: strong evidence for    
    • tramadol
      • indications
        • treatment option for patients with symptomatic arthritis
      • technique
        • weak opioid mu receptor agonist
          • good evidence for mid term (8-13 weeks) improvement in pain and stiffness over placebo
      • outcomes
        • AAOS guidelines: strong evidence for
    • rehabilitation, education and wellness activity 
      • indications 
        • first line treatment for all patients with symptomatic arthritis
      • technique 
        • self-management  and education programs
        • combination of supervised exercises and home program have shown the best results
          • these benefits lost after 6 months if exercises are stopped
      • outcomes
        • AAOS guidelines strong evidence for  
    • weight loss programs
      • indications
        • patients with symptomatic arthritis and BMI > 25
      • technique
        • diet and low-impact aerobic exercise
      • outcomes
        • AAOS guidelines: moderate evidence for
    • controversial treatments
      • acupuncture
        • AAOS guidelines: strong evidence against 
      • viscoelastic joint injections
        • AAOS guidelines: strong evidence against 
      • glucosamine and chondroitin
        • AAOS guidelines: strong evidence against
      • needle lavage
        • AAOS guidelines: moderate evidence againnst
      • lateral wedge insoles
        • AAOS guidelines: moderate evidence against
  • Operative
    • high-tibial osteotomy 
      • indications
        • younger patients with medial unicompartmental OA
      • technique
        • valgus producing proximal tibial oseotomy
      • outcomes
        • AAOS guidelines: limited evidence for
    • unicompartmental arthroplasty (knee) 
      • indications
        • isolated unicompartmental disease
      • outcomes
        • TKA have lower revision rates than UKA in the setting of unicompartmental OA
    • total knee arthroplasty
      • indications
        • symptomatic knee osteoarthritis
        • failed non-operative treatments
      • techniques
        • cruciate retaining vs. crucitate sacrificing implants show no difference in outcomes
        • patellar resurfacing 
          • no difference in pain or function with or without patella resurfacing
          • lower reoperation rates with resurfacing
        • drains are not recommended
 
 

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(OBQ09.181) According to the latest recommendations made by the AAOS in their clinical guidelines for the treatment of osteoarthritis (OA) of the knee, which of the following nonoperative treatment modalities has the weakest supporting evidence for the treatment for knee osteoarthritis? Review Topic

QID: 2994
1

Weight loss

1%

(23/3221)

2

Activity modifications

1%

(26/3221)

3

Quadriceps strengthening

4%

(136/3221)

4

Intra-articular hyaluronic acid injections

88%

(2838/3221)

5

Intra-articular corticosteroid injections

6%

(191/3221)

ML 2

Select Answer to see Preferred Response

PREFERRED RESPONSE 4

(OBQ13.241) Which of the following non-operative treatments for osteoarthritis has the best evidence to support its use? Review Topic

QID: 4876
1

Combination of supervised and home exercise programs

84%

(3169/3794)

2

Hyaluronic acid injections

3%

(96/3794)

3

Lateral heel wedge

1%

(33/3794)

4

Acetaminophen

12%

(441/3794)

5

Glucosamine

1%

(33/3794)

ML 2

Select Answer to see Preferred Response

PREFERRED RESPONSE 1

(OBQ13.31) Which of the following statements is true about racial disparities in total joint arthroplasty? Review Topic

QID: 4666
1

The rate of surgical intervention for African American males is lower than white or Hispanic males

88%

(3489/3987)

2

The rate of surgical intervention for Hispanics is higher than that for whites

2%

(61/3987)

3

The rate of surgical intervention for white males is lower than for African American males

4%

(143/3987)

4

There is no difference in the rate of surgical intervention between whites, Hispanics, or African Americans

5%

(215/3987)

5

The rate of surgical intervention is equal for Hispanic and white males

1%

(56/3987)

ML 1

Select Answer to see Preferred Response

PREFERRED RESPONSE 1

(OBQ11.201) Which of the following treatment recommendations lacks Level 1 supporting evidence (Grade A Recommendation) according to the the American Academy of Orthopaedic Surgeons (AAOS) Guidelines for Treatment of Knee Arthritis (OA)? Review Topic

QID: 3624
1

Recommend patients be encouraged to participate in low-impact aerobic fitness exercises

4%

(113/2800)

2

Recommend against glucosamine and/or chondroitin sulfate or hydrochloride for patients with symptomatic OA of the knee

25%

(698/2800)

3

Recommend for arthroscopic partial meniscectomy as an option in patients with symptomatic OA of the knee who also have primary signs and symptoms of a torn meniscus

56%

(1568/2800)

4

Recommend for weight loss in patients who are overweight (as defined by a BMI>25)

6%

(164/2800)

5

Recommend against performing arthroscopy with debridement or lavage in patients with a primary diagnosis of symptomatic OA of the knee

9%

(246/2800)

ML 4

Select Answer to see Preferred Response

PREFERRED RESPONSE 3
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