Musculoskeletal Disorders

Musculoskeletal Disorders

1. Osteoarthritis

   • Joint cartilage degeneration (wear&tear). Non inflammatory The most common form of arthritis
   • clinical features
     • stiffness & pain woth movement
     • transient morning stiffness <30min
     • deep localised ache in a joint
     • gradual onset of pain: exercise then at night & rest
       • increasing with disease duration
     • gait disturbane
     • joint swelling
     • Crepitus
       • cracks or creaks on movement
     • hips, knees, neck & hands
   • Risk factors
     • Age
       • 50% of &gt;65 have x-ray evidence of OA
     • Joint trauma or injury
     • abnormality in joint shape
     • Mechanical repetitive stress
     • Heredity
     • female
     • obesity
     • lack of exercise
   • Management
     • Non pharmacological
       • Patient education
       • wight loss
       • exercise, physiotherapy, hydrotherapy
       • appropriate foot wear
       • knee/ hip replacement
     • Pharmacological
       • Paracetamol
         • first-line therapy
       • NSAIDS
         • Act on the COX enzyme system. Inhibits synthesis of prostaglandins &amp; thromboxanes. Reversibly inhibits COX1 &amp; COX2 enzymes as well as thromboxane synthase. eg ibuprofen, diclofenac, naproxen Anti-inflammatory effect mainly due to inhibition of COX2. Therapeutic effects: 1. anti-inflammatory 2. anti-pyretic 3. analgesic
       • Corticostereoids
         • intra-articular corticostereoid injections

2. Gout

   • Painful inflammatory monoarthritis of joints & soft tissue due to deposition of sodium urate crystals in one or more joints.
     • raised uric acid in blood which crystallises out in joints/tendons and surrounding tissue
       • under excretion of uric acid (90%)
       • overproduction of uric acid (10%)
       • Uric acid - final product of purine metabolism
     • intermittent painful attacks
     • men
     • joints of the feet and ankle most commonly affected (podagra)
     • red, hot, swollen
   • Triggers
     • Trauma
     • Drugs eg diuretics, cytotoxics
     • alcohol abuse
     • Dietary excess
     • severe dieting
     • obesity
     • stress
   • Management
     • non-pharmacological
       • reduce alcohol intake
       • Avoid beer, stout, port and other fortified wines
       • avoid fructose
         • sugary soft drinks
         • fructose rich fruits
       • reduce weight
       • restrict intake of purine-rich foods
         • red meat
         • liver
         • kidneys
         • shellfish
         • yeast extract
       • include vegetable source of protein in diet
       • restrict overall protein intake
       • drink >2L of water daily
     • acute gout
       • NSAIDs
         • first line
         • diclofenac, naproxen
       • COXIBs
         • lower GI risks than NSAIDs
         • etericoxib
           • only COXIB licensed for gout
       • Colchicine
         • -factors (chemotactic) released which stimulates neutrophil migration into the joint -neutrophils engulf urate crystals &amp; release inflammatory mediators
         • MOA: reacts with tubulin & selectively inhibits microtubule assembly: reduces neutrophil migration into affected joint & phagocytosis
         • SE: GI (abdo pain & diarrhoea)
         • 500 mcg 2-4 times a day until symptom resolution
           • MAX 6mg/course
           • not to be repeated within 3 days
         • do not use in pregnancy!
         • drug of choice for
           • hypertension & HF (no fluid ret)
           • renal impairment
           • PUD
           • anti coagulant patients
       • Corticostereoids
       • Do not use aspirin at analgesic doses - can worsen gout
     • Chronic gout
       • prophylaxis initiated 2-3 weeks after acute attack
       • xanthine oxidase inhibitors
         • allopurinol
           • 1st choice
           • co administration of colchicine or NSAIDs for 1st 6mths
         • febuxostat
       • uricosurics
         • Sulfinpyrazone
         • increases excretion of uric acid in urine by inhibiting its reabsorption

3. Rheumatoid Arthritis

   • pathogenesis of RA 1.antigen presenting cell 2.activate T cells - produce interleukins &amp; gamma interferon 3.stimulates B cells to differentiate into plasma cells 4. stimulate macrophages - IL1 &amp; TNF-a (stimulate osteoclasts and fibroblasts) 5.autoantibodies (RF) produced from plasma cells 6.RF binds with IgG - immune complex - joint deposition 7.fibroblasts - produce enzymes - destroy joint collagen
   • chrinic, progressive symmetrical polyarthritis of 3 or more joints
     • small joints most likely eg hands & wrists
       • but may also affect: hips, elbows, shoulders, knees & ankles
     • autoimmune disease due to inflammation in the lining of membranes
       • mostly synovial joints
     • malaise, anorexia withs symmetrical tender & swollen joints
       • pain, swelling and stiffness in joints
     • diagnostic criteria: at least 4 of
       • early morning stiffness >1hr
       • arthritis of 3 or more joints
       • arthritis of the hand joints
       • rheumatoid nodules
       • x-ray changes typical for RA
       • serum rheumatoid factor
     • extra-articular features of RA
       • rheumatoid nodules
       • anaemia
       • peripheral neuropathy
       • kidney disease
       • lung disease
       • CV disease
     • degeneration of cartilage, bone and joint supporting structures
   • Management
     • non pharmacoloical
       • rest
       • physiotherapy
       • psychological support
       • occupational therapy
     • DMARDs
       • -reduce inflammation and delay progression of joint damage &amp; disability -preserve joint function -no evidence of superiority of one DEMARD over another
       • onset of effect: 4-16 weeks
         • full therapeutic response: 4-6mths
       • 1st line: METHOTREXATE
         • more rapid onset of action than other DMARDs
         • antifolate
           • inhibits dihydrofolate reductase
         • cytotoxic & immunosuppressant
         • 7.5-10mg/WEEK
           • max 20mg/week max SC 25mg/week
           • +folic acid on diff day
         • rapid absorption from gi
         • teratogenic
         • ADRs
           • GI
           • Liver
           • blood dyscrasias
           • pulmonary
         • monitoring
           • chest x-ray (last 6mths)
           • FBC, LFTs, U+E, creatinine
             • every 2 weeks until stable for 6 weeks then every 1mth
           • some patients: pulmonary function tests
       • sulfasalazine
       • hydroxychloroquine
       • leflunomide
       • gold salts
     • Biologicals
       • TNF-alpha: affects cellular function via action at specific membrane bound TNF receptors
         • anti TNF drugs neutralise the pro-inflammatory activity of TNF-alpha
           • only use if at least 2 DMARDs tried and failed!!
           • adalimumab
             • MOA: binds to TNF-alpa neutralising its activity
             • with MTX or alone
           • etanercept
             • MOA: competitive inhibitor of TNF-alpha at its receptor site
             • with MTX or alone
           • infliximab
             • MOA: binds to TNF-alpha neutralising its activity
             • must be given with MTX