Definition - Slowly progressive degenerative disease characterised
by the gradual loss of articular cartilage
Risk Factors - age >50 years
- female gender
- obesity
- genetic factors
- physical/manual occupation
- knee malalignment
- high BMD ?
Differential diagnosis Epidemiology - About 8.5 million people in the UK have OA
- OA is common in women and becomes more common with advancing age
- 2% of women with a mean age of 71 develop
radiographic knee OA every year, compared with 1.4% of men
- 1% of
women develop symptomatic knee OA every year, compared with 0.7% of men
- The prevalence of currently recorded
diagnosis of knee OA in patients >45 years old is 1.1%
- The
estimated prevalence of all those who had had knee OA diagnosed at some point was 5.5%
Aetiology - Exact aetiology for OA is
unknown:
- Age, hereditary predisposition,
female gender, and obesity are associated with increased risk of OA
- Articular congenital deformities or trauma to the joint also enhance
the risk of developing OA
- High BMD and low oestrogen
status, such as in post-menopausal women, may be associated with higher
risk of knee and hip OA
- The above factors might lead to a joint
environment that is susceptible to trauma and to external mechanical
stressors that are exacerbated by certain physical activities
- Local
mechanical factors further facilitate the progression of the disease
- Periarticular muscle weakness
- Misalignment
- Structural joint abnormality (i.e., meniscal tear)
Clinical features - Pain
- Functional difficulties
- Knee, hip, hand, or spine involvement
- Bony deformities
- Limited range of motion
- Malalignment
- Tenderness
- Crepitus
- Stiffness
- Shoulder, elbows, wrists, or ankles involvement
- Effusion
- Antalgic gait
Pathophysiology Investigations- Xray
- new bone formation (osteophytes), joint space narrowing, and subchondral sclerosis and cysts
- CRP and ESR
- OA is a clinical diagnosis, but inflammatory markers should be ordered
if inflammatory arthritis is a possible differential
- For example, in
an older patient who presents with a knee effusion.
- MRI
- MRI is not indicated for the diagnosis of simple OA in most joints. It
is used to rule out other aetiologies for hip or knee pain, such as
avascular necrosis.
- => Cartilage loss, bone marrow lesions, and meniscal tears
Managementa) conservative- Approaches depend on site of OA and include patient education
- Exercise programmes, physiotherapy and occupational therapy, quadriceps-strengthening exercises, knee braces, correct footwear, and patellar bracing or taping for patellofemoral pain
- Proper use of a cane in the contralateral hand to the affected hip or knee can also reduce pain and improve function.
b) medical - Local analgesics should be used as first-line therapy
- Capsaicin, methylsalicylate cream, or topical NSAIDs
- Paracetamol should be added if local therapies alone fail to control symptoms.
- Intra-articular corticosteroid injections
- Suitable for acute exacerbation of symptoms
- Especially effective for knee pain
- The beneficial effect is temporary and usually lasts for a few weeks, but it varies among patients
- Further NSAIDs / opioids
c) surgical- Replacement surgery is appropriate for OA of the hip and knee
- Osteotomy is suitable for knee OA
- Arthroplasty, osteotomy, and arthrodesis are options for thumb OA
Prognosis- OA is a chronic slowly progressive disease and is almost ubiquitous
with advancing age
- A combination of different
modalities of treatment can provide adequate pain control and preserve
function and quality of life for many patients
- Despite treatment, most
patients usually continue to have some degree of pain and functional
limitation affecting their desired activities and quality of life
- Complications of medication, particularly NSAIDs, are also problematic
- In patients who fail to respond to medical and non-medical therapies,
total joint replacement provides good long-term pain relief for most
people
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