osteoarthritis
OSTEOARTHRITIS

Osteoarthritis is a chronic progressive disease where there is degeneration & loss of articular cartilage that occurs together with new bone formation at the joint surfaces and margins, that causes pain and deformity.

The patient experiences pain, stiffness, decreased movement, inflammation and crepitus.

The pain is usually aggravated by pain and relieved by rest.

Principles of Therapy

  • Goals in treating patients with knee or hip OA include reducing joint pain & stiffness, maintaining & improving joint mobility, decreasing physical disability, improving quality of life, limiting progression of joint damage & keeping the patient knowledgeable on the nature of their disease & management
  • Used together with pharmacotherapy to decrease pain & improve functioning & quality of life
  • Drug therapy for pain management is most effective when combined with non-pharmacotherapy
  • Symptom management is achieved with pain medications which lead to improvement in functional status & disability

Pharmacotherapy

Oral Analgesics

Paracetamol

  • Oral analgesic of choice for patients with mild-moderate pain due to its safety & efficacy profile
  • Preferred analgesic drug for long-term use, but should be used with caution in patients with liver impairment
  • Pure analgesic with no disease-modifying property
  • Considered 1st prior to using NSAIDs or opioids
  • Drug of choice for analgesia in patient with impaired renal function

Nonsteroidal Anti-inflammatory Drugs (NSAIDs)

  • Used for treating acute pain due to anti-inflammatory & anti-nociceptive effect
  • Added to or substituted for Paracetamol or topical NSAIDs when it is ineffective or insufficient in relieving OA pain
  • 2nd-line for managing OA pain due to its relative toxicity
    • Any NSAID monotherapy may be used if patient is at low risk for both GI & CV diseases
    • For patients at high risk for cardiovascular diseases but with low GI risk, Naproxen or COX-2 selective NSAIDs may be considered
      • Celecoxib is preferred over non-selective NSAIDs for its lesser adverse effects
    • For patients at high risk for GI disease but with low CV risk, COX-2 selective NSAID alone or non-selective NSAIDs in combination with a proton pump inhibitor may be considered
    • Should be used for the shortest possible period of time at the lowest effective dose
    • In patients with both high CV & GI risk, NSAIDs therapy should be deferred
    • Increase to full anti-inflammatory doses only if lower doses do not provide adequate symptomatic relief
  • Combination with Paracetamol is effective in managing pain with lower NSAID dose & possible toxicity

Opioid

  • Eg Dihydrocodeine, Oxycodone, Tramadol
  • Acute pain can often be managed without opioids; 3 days or less & not greater than 7 days will often be sufficient for opiod prescription  
  • Recommended in patients with moderate-severe OA pain who have failed to respond to, or unable to tolerate pharmacologic & nonpharmacologic treatments & are unwilling or unqualified to undergo total joint arthroplasty
  • Not recommended for patients with hand OA
  • Non-narcotic opioids may be combined with Paracetamol to provide similar analgesic effect
  • If used for acute pain, the lowest possible effective dose & exact quantity of immediate-release opioids should be prescribed 
  • Narcotic opioids may be an option in managing patients with inadequate response or contraindications to other analgesics
    • May cause CNS depression or addiction & has lack of disease-modifying properties

Drugs for Neuropathic Pain

  • Eg Duloxetine
  • Studies have shown that Duloxetine significantly reduced pain & improved function in patients suffering from pain due to knee OA
  • Recommended for treatment of chronic musculoskeletal pain & discomfort caused by OA
  • Conditionally recommended for patients with knee OA who had treatment failure after initial therapy, & for symptomatic knee OA patients who had inadequate clinical response after nonpharmacologic & pharmacologic treatment who are unwilling or not qualified to undergo total joint arthroplasty

Topical Analgesics

  • Used as an adjunctive treatment in patients with knee or hand OA who have mild-moderate pain who do not respond to Paracetamol & do not want to use systemic therapy
  • Not recommended for hip OA
  • Capsaicin cream causes depletion of substance P neuropeptide causing decreased sensation in the local area; recommended for hand OA
  • Topical NSAIDs have similar efficacy with oral NSAIDs in treating patients with OA pain as shown by clinical trials
    • Produce high concentration of the drug at the local site with reduced systemic side effects
    • Recommended for knee or hand OA
  • Salicylate-containing products has a short-term benefit in decreasing pain by increasing local blood flow

Intra-articular Injections

  • Indicated only if non-pharmacotherapy & systemic therapies have failed or are contraindicated
  • Corticosteroids
    • Indicated for fast & short-term relief of pain & swelling of joints
    • Synovial fluid is 1st aspirated from the joint to reduce swelling & it allows a higher concentration of the drug at the site of action with a lower risk of systemic side effects
    • Large joints should not be injected for >3x/year & smaller joints for >4x/year
    • Interval of injections to the same joint should not be shorter than 3 month
  • Hyaluronic acid
    • A naturally occurring substance that contributes to the elasticity & lubrication of synovial & cartilage within the joints
    • Used primarily for its long-term reduction in pain intensity & improvement of joint mobility
    • Study showed greater benefit for knee OA from 8 weeks extending up to 26 weeks, as compared to corticosteroids

Other Drugs

Chondroitin & Glucosamine

  • Naturally present in the articular cartilage that acts on its formation & repair
    • Suggested as a disease-modifying OA drug by some clinical studies
  • Requires 4 weeks of therapy before symptom improvement is noted
    • Should discontinue after 6 months of use if no apparent response is noted

Diacerein

  • Metabolized to rhein, it stimulates prostaglandin E2 synthesis while inhibiting production of interleukin- 1
  • Clinically modest but statistically significant improvement in pain resulting from hip or knee OA

Avocado-Soybean Unsaponifiables (ASU)

  • A combination of 1/3 avocado oil & 2/3 soya oil, used as a dietary supplement
  • Possibly reduces pain & stiffness during walking & other daily activities, & improves joint function in patients with OA

Non-Pharmacological Therapy

Exercise

  • Eg quadriceps muscle strengthening, resistance training, aerobic or flexibility exercises
  • Important in the management strategy of patients with OA for both prevention & treatment of symptoms
  • Should be individualized according to the patient’s needs, abilities & preferences
  • Improves general physical health, reduces risk for development of chronic diseases & helps in weight control
    • May also improve patient’s overall quality of life through its psychological & social benefits
    • Helps to improve physical functioning & reduce pain in patients with knee OA through increase muscle strength, range of motion, aerobic capacity & endurance
  • Land & aquatic exercises are both recommended for patients with symptomatic knee & hip OA
    • The choice between land & aquatic exercises depend on the patient’s preference & ability
    • Aquatic exercises are preferred for patients with hip OA because of lesser stress to the joints due to buoyancy
  • Tai chi is recommended for patients with knee OA
    • Several studies have shown pain improvement in patients practicing tai chi as compared to those with out exercise

Weight Reduction

  • Patients with symptomatic OA, esp of the knee & hip, should be encouraged to lose minimum of 5% of their body weight & maintain their weight at a lower level with an appropriate program of dietary modification & exercise

Physical Therapy

  • Eg range of motion exercises, soft tissue mobilization, muscle strengthening & stretching
  • Employed in addition to active exercise programs that aims to relieve pain & stiffness, & improve joint movement & overall function

Thermotherapy

  • Involves application of heat or cold to manage symptoms of OA
  • Cold therapy is most effective during acute flare of OA which reduces inflammation & pain, blocks nerve impulses & muscle spasms to the joint
    • Applied in the affected area for 20 minutes, 5 days/week for 2 weeks
  • Heat therapy applied for 15-20 minutes may reduce pain & stiffness by promoting relaxation, joint flexibility & blood flow to the joint

Mechanical Interventions

Assist Devices

  • Jar openers, key turners & pull tabs are recommended for patients with hand OA

Splints

  • Conditionally recommended for patients with trapeziometacarpal joint OA

Knee Braces

  • May increase stability, support weak muscles & joints, & redistribute weight load to the joint
    • May also help decrease the risk of falling
  • Limited evidence support its use in knee or hip OA

Patellar Taping

  • May be used for short-term, intermittent treatment of knee OA by stabilizing the knee joint & distributing stress & joint pressure
  • Medially directed patellar taping is recommended for knee OA

Wedge Insoles

  • May be used to provide pain relief & improve ambulation in patients with knee OA
  • Medially-wedged insoles - conditionally recommended for patients with lateral compartment OA
  • Laterally-wedged subtalar strapped insoles - conditionally recommended for patients with medial compartment OA

Walking Aids

  • May be used by patients with knee or hip OA

Alternative Therapy

Acupuncture

  • Conditionally used for knee OA patients with chronic moderate to severe pain who are unwilling or not qualified for knee arthroplasty
  • May be used as an adjunct for symptomatic relief of pain & improvement of knee function by triggering the endogenous opioid pathways

Transcutaneous Electrical Nerve Stimulation (TENS)

  • Non-invasive therapy that relieves pain by inhibiting the transmission of painful stimuli
  • Provides short-term relief of OA knee pain, reduces stiffness & improves range of motion
    • Effects last for 4 weeks
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