osteoarthritis of the knee

Etiology

• see osteoarthritis
• leg length inequality may be risk factor
• meniscectomy is a risk factor for early osteoarthritis of the knee
• obesity is the most modifiable risk factor
• weight bearing activity in persons with reduced leg muscle mass is associated with increased risk of knee osteoarthritis

Epidemiology

• prevalence of symptomatic osteoarthritis of the knee has increased from 1974 to 2004
  • 13% to 26% white females
  • 9% to 20% white males
  • 10% to 17% black females
  • 6% to 16% black males
• overall prevalence of radiologically defined osteoarthritis has not changed

Clinical manifestations

• pain after stressful or prolonged weight-bearing
• pain after climbing stairs
• pain is relieved by rest
• joint effusion after weight bearing may occur
• loss of range of motion
• varus or valgus angulation may occur with disease progression

Diagnostic criteria

• at least 3 of the following
  • age > 50 years
  • stiffness lasting < 30 minutes
  • crepitus
  • bony tenderness
  • bony enlargement
  • no palpable warmth

Laboratory

• joint aspiration of effusion
  • non-inflammatory fluid; WBC < 3000/uL
  • small, cool effusions need not be aspirated

Radiology

• X-ray of the knee (bilateral)
  • standing views appropriate to confirm diagnsosis
    • demonstrate joint space narrowing better than supine views
  • >70% of population >40 years of age with radiographic evidence of osteoarthritis
• MRI detects structural abnormalities consistent with osteoarthritis of the knee in most older people without radiographic evidence for knee osteoarthritis, regardless of the presence of pain

Complications

• increased risk for depression
  • risk increases with severity of knee osteoarthritis
• fatigue is strongest predictor of reduced activity

Differential diagnosis

• anserine bursitis
• patellofemoral pain syndrome
• tendonitis
• internal derangement of the knee
  • meniscus tear - synovial fluid: bloody effusion
  • osteonecrosis - plain radiograph, MRI if early
• inflammatory joint disease
  • rheumatoid arthritis
  • lupus arthritis
  • psoriatic arthritis
• crystalline arthropathy
  • gout
  • calcium pyrophosphate deposition (pseudogout)
• septic arthritis
• joint instability
• referred pain from the hip

Management

• weight reduction via calorie restriction
  • weight reduction via diet & exercise in obese or overweight patients results in small improvements in knee pain of uncertain clinical significance
  • weight reduction with favorable effect of development & progression of knee osteoarthritis in obese patients
• avoidance of pain-inducing activities
• pharmaceuticals (also see osteoarthritis)
  • acetaminophen of no benefit
    • less effective than NSAIDs
    • no better than placebo
  • NSAIDs - diclofenac most effective agent on U.S. market
    • NSAIDs associated with greater loss of medial minimum joint space width compared with other drugs
    • avoid oral NSAIDS in patients with coronary artery disease, heart failure, chronic renal failure & peptic ulcer disease
  • topical diclofenac
    • efficacy similar to oral diclofenac with adverse effect profile similar to placebo (except for application reactions)
    • American College of Rheumatology recommends topical NSAIDs rather than oral NSAIDs for elderly (>= 75 years of age) regardless of whether or not they are doing well on oral NSAIDs
    • associated with more skin reactions
      • considerably more expensive than oral NSAIDs
    • placebo effect of topical application
  • topical salicylates
    • efficacy poor to moderate
  • topical capsaicin 0.025% applied QID
    • poor to modest efficacy
  • oral methotrexate once weekly (6-week escalation 10 to 25 mg weekly)
    • reduction in pain & stiffness at 6 months
    • subcutaneous methotrexate not evaluated
  • weekly semaglutide reduces pain, improves physical function in patients with obesity & knee osteoarthritis
  • nerve & joint injections
    • glucocorticoid joint injection
      • exclude infection with joint aspiration & synovial fluid analysis if signs of inflammation
      • predictors of response difficult to identify - effusion noted as possible predictor to response - injection under ultrasound guidance may improve likelihood of response - triamcinolone equivalent to methylprednisolone
      • benefit modest at best; of no benefit
      • may hasten cartilage loss
      • max once every 4 months
      • in patients with type-2 diabetes, extended-release triamcinolone associated with less hyperglycemia than immediate-release triamcinolone
    • intramuscular joint injection of glucocorticoid may be as effective as intra-articular injection
    • hyaluronic acid injections not recommended
      • osteoarthritis not responding to other treatment
      • better than intra-articular saline
      • no better than glucocorticoid injection
      • does not hasten cartilage loss
      • ineffective, expensive
      • clinicians not following recommendations
    • glucocorticoid injections are as safe as hyaluronic acid injections & disease progression is similar
    • intra-articular saline better than oral NSAIDs
    • glucocorticoid joint injection prior to exercise therapy of no benefit
    • placebo effect of injection > topical placebo > oral placebo
    • studies on intra-articular stem cell injections of poor quality
    • ultrasound-guided genicular nerve block
      • 3 injections of 5.7 mg celestone chronodose (1 ml) & 0.5% bupivacaine (3 ml) to the inferomedial, superomedial, & superolateral genicular nerves may improve osteoarthritis pain for 12 weeks
  • serotonin norepinephrine reuptake inhibitors (SNRI)
    • duloxetine, venlafaxine (low-certainty evidence)
    • duloxetine reduces knee pain & improves physical function in mild-moderate osteoarthritis
    • no significant benefit of duloxetine in end-stage osteoarthritis
  • joint effusion: spironolactone 25 mg PO QD for 2 weeks may be effective
  • use of beta-blockers is associated with less arthragias & less use of opioids & other analgesics for symptomatic large-joint osteoarthritis
  • tramadol of minimal benefit with significant adverse effects
  • opiates as a last resort
  • glucosamine, chondroitin sulfate (see GAIT trial)
    • MKSAP19 says do not use
    • some clinical trials have found benefit
    • may reduce cartilage loss in some regions of the knee
    • combined chondroitin sulfate & glucosamine as effective as celecoxib
    • no better than placebo
    • safety profile equivalent to placebo
    • not recommended; not useful
    • pharmaceutical-grade chondroitin sulfate 800 mg/day as effective as celecoxib
  • only celecoxib & glucosamine sulfate of long-term benefit, albeit small benefit
  • colchicine 0.5 mg QD may reduce need for total knee arthoplasty
  • turmeric may be of some benefit in reducing knee pain
    • long-term benefit unlikely
  • of no benefit
    • vitamin D of no benefit
    • zoledronate of no benefit
    • biologic agents of no benefit
    • botulinum toxin of no benefit
    • platelet-rich plasma of no benefit
• aerobic exercise may be useful
  • no specific exercise program proven superior
  • supervised exercise 3 times a week
    • improve aerobic capacity, quadriceps strength, or lower extremity performance
  • walking may be beneficial in rehabilitation {20-30 minutes at least once a week}
  • walking exercise may be useful for patients for mild or intermittent symptoms
  • moderate intensity aerobic exercise may not be achievable in some elderly patients
  • self-management program including low-impact aerobic exercise
  • physical activity reduces risk of disability
  • Low-to-moderate physical activity might be protective
  • daily walking may delay functional limitations
  • land-based exercise of benefit in terms of reduced knee pain & improvement in physical function
    • benefit sustained >= 2-6 months after cessation
  • stepwise program may benefit less motivated patients
    • step 1: internet-based exercise program
    • step 2: non-responders at 3 months: biweekly telephone coaching to address barriers to physical activity
    • step 3: non-responders at 6 months: in-person physical therapy
  • internet-base exercise therapy convenient & effective in reducing pain & increasing function
• quadriceps-strengthening activities - twice weekly
  • high-intensity strength training no better than low-intensity strength training or an attention control in adults with knee osteoarthritis
  • individualized self-directed strengthening & physical activity with automated text messaging encouraging adherence reduces pain & improves function
  • strength training to increase leg muscle mass may be of benefit
• orthotics:
  • correction of pronation of foot can relieve knee pain
  • stable, supportive shoes better for pain than flat, flexible shoes
  • lateral wedge sole inserts not effective for varus deformity of knee
• physical therapy 3 times per week for 4 weeks for patients not responding to therapy
  • physical therapy may benefit patients with substantial comorbidities
  • physical therapy better than glucocorticoid injection
  • physical therapy better than saline injections, but difference not significant
• weight loss, physical activity, & self-management education
  • delivery of patient-specific osteoarthritis treatment recommendations to primary care providers through electronic medical record in combination with telephone-based patient intervention focused on weight management, physical activity, & cognitive behavioral therapy for pain management of benefit
• Tai Chi as effective as physical therapy
• cognitive behavioral therapy (CBT)
  • beneficial for patients with osteoarthritis & insomnia
  • (CBT) may be useful for patients intolerant of NSAIDs
• raised seating alleviates forces across the knee & hip
• use of a cane
• knee brace may provide symptomatic relief
  • valgus bracing for medial knee OA
  • no evidence to support the use of valgus knee braces
• special biomechanical shoes
  • cost is considerable, overall clinical value is unclear
• acupuncture can help patients with OA of the knee
  • effective for patients with chronic pain due to osteoarthritis
  • can improve short & long-term physical function
  • can provide only short-term pain relief
  • not recommended
  • statistically significant benefits are small & do not meet thresholds for clinical relevance
  • long-term benefit unklikely
• cooled radiofrequency ablation on 4 genicular nerves may provide pain relief in for patients with refractory knee osteoarthritis
  • genicular nerve block with anthesthetic/glucocorticoid may provide short-term pain relief diminishing over 12 weeks
• unproven therapies
  • insufficient data to recommend electrotherapy (TENS)
  • omega-3 fatty acids without benefit
    • low-dose fish oil (0.45 g EPA + DHA daily, blended with high-oleic acid sunola oil) may be of benefit
    • krill oil (2000 mg/day) of no benefit
  • coenzyme Q10 without benefit
  • unloading shoes of no benefit
  • platelet-rich plasma does not improve knee pain or slow disease progression
  • arthroscopic lavage, debridement, closed lavage
  • cupping therapy
• surgery
  • arthroscopic surgery
    • indications:
      • degenerative meniscal tear
        • osteoarthritis with joint buckling, joint instability or locking, or symptomatic mechancal disorder
    • in most cases not indicated
  • arthroplasty (knee replacement)
    • may improve pain, activities of daily living, & quality of life at 1 year at the cost of increased risk for venous thromboembolism (RR=4)
  • high tibial osteotomy (individuals too young for knee replacement)
  • allograft meniscal transplantation (new technique 1998)
  • knee cartilage repair (MACI)
  • arthroscopic lavage, debridement not indicated
  • reduces cardiovascular risk possibly due to increased exercise capacity & decreased NSAID use
  • implantable shock absorber superior to high tibial osteotomy
• no intervention favorably changes natural course of knee OA

More general terms

• osteoarthritis (OA)

Additional terms

• knee
• knee pain
• patellofemoral pain syndrome; chondromalacia patella (PFPS)
• pes anserine bursitis
• tendonitis (tendon injury)

Patient information

osteoarthritis of the knee patient information