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Osteoarthritis

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Overview

Osteoarthritis (OA) is a degenerative joint disorder whose prevalence increases with age. It’s also known as the “wear and tear” of joints.

It most commonly affects the knee, hip, proximal interphalangeal (PIP) and distal interphalangeal joints (DIP), and the spine – particularly in the lumbar and cervical regions.

OA in other joints such as the ankle and wrist is rarer and more suspicious of underlying aetiology e.g. crystal arthropathy/trauma.

Epidemiology

  • OA is the most common form of arthritis and is more common in women than men
  • Its prevalence increases with age and is more common in people >50yrs

Risk Factors & Associations

  • >50yrs
  • Female sex
  • Family history of OA
  • Obesity
  • Physically demanding occupation
  • Sports
  • Trauma/injury
  • Hypermobility

Presentation

Patients present with joint pain that is worse on activity and relieved with rest:

  • Common joints are:
    • Knees
    • Hip
    • Hands
    • Lumbar spine
    • Cervical spine
  • Morning stiffness that lasts <30 minutes
  • May have a history of long-term physical labour
  • Hand OA usually affects the proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints
    • OA spares the metacarpophalangeal (MCP) joints. If the MCP joints are affected, rheumatoid arthritis should be considered
    • OA in other joints such as the ankle and wrist is rarer and more suspicious of underlying aetiology e.g. crystal arthropathy/trauma.
  • OA may have local tenderness over the joint line
  • Knee locking or giving way
  • Bony deformities may be seen (see signs on examination)
  • Active and passive range of movement may be reduced and painful

Signs on examination

  • Squaring of the base of the thumb (first carpometacarpal joint) is a sign of hand OA
  • In advanced knee OA: new bone formation causes bony swellings around the knee joint
    • Enlargement of the DIP joints – Heberden nodes
    • Enlargement of the PIP joints – Bouchard nodes
  • There may be palpation of crepitus during movement of the joint
  • There may be small effusions
  • There may be joint line tenderness
  • Patients may have an abnormal gait

Diagnosis

OA can be clinically diagnosed if all three of the following apply:

  • ≥45yrs
  • Activity-related joint pain
  • No morning stiffness/stiffness <30mins

Imaging is not routinely performed unless there are atypical features:

  • History of recent trauma
  • Prolonged joint stiffness
  • Rapid worsening of symptoms
  • Deformity
  • The presence of a hot, swollen joint
  • Concerns about infection/malignancy

X-ray findings

If an x-ray is performed, it may show features remembered with LOSS:

  • Loss of joint space
  • Osteophytes
  • Subchondral sclerosis
  • Subchondral cysts

Differential Diagnoses

Rheumatoid arthritis (RA)

  • Usually a symmetrical small joint polyarthritis affecting the MCP and PIP joints and may spare the DIP joints
  • RA is associated with prolonged morning stiffness (>30 minutes)
  • Joint pain and stiffness are worse with rest and improve with movement
  • There can also be evidence of systemic upset, such as fatigue, low mood, and fever

Psoriatic arthritis

  • May have associated psoriatic skin lesions, but these are not necessary
  • May present with symmetrical or asymmetrical arthritis and be similar to RA
  • Joint pain and stiffness are worse with rest and improve with movement
  • Nail changes such as pitting and onycholysis are present

Trochanteric bursitis (greater trochanteric pain syndrome)

  • There is tenderness over the lateral aspect of the hip which is absent in OA

Gout and pseudogout

  • The onset of pain is more acute (usually over a few hours)
  • During an attack, the joint is hot, erythematous, and tender
  • Gout classically affects the first metatarsophalangeal joint
  • Pseudogout typically affects the wrist, shoulders, and knee

Avascular necrosis

  • More common in the hip and knee joints and presents over months with pain
  • There is usually a risk factor for its development, such as long-term corticosteroid use and chemotherapy

Management

Overview

All patients should be given lifestyle advice, help with weight loss (if appropriate), and therapeutic exercises aimed at muscle strengthening and general aerobic fitness.

  • 1st-line: paracetamol and topical NSAIDs for OA of the hand or knee
  • 2nd-line: oral NSAID/COX-2 inhibitor + proton pump inhibitor
  • Consider intra-articular corticosteroid injections (these provide relief for 2-10 weeks)
  • Consider short-term courses of low-dose opioids
  • Refer for joint replacement surgery:
    • Decisions are generally made on a case-by-case basis and referral should be made before the person has severe functional limitation/pain
    • If joint problems are causing a significant impact on a patient’s quality of life and initial treatments have been unsuccessful, then a referral for joint replacement surgery would be appropriate

Complications

  • Joint deformity (Heberden’s and Bouchard’s nodes)
  • Functional impairment (e.g. difficulty walking)
  • Problems with performing tasks at work
  • Gastrointestinal bleeds and renal impairment due to NSAID use

Prognosis

In general:

  • Hand OA has a generally good prognosis and interphalangeal joint involvement usually becomes asymptomatic after a few years, however, involvement of the CMCs is associated with a poorer prognosis
  • Hip involvement is associated with a poorer prognosis and many people require a hip replacement within 5 years of being diagnosed
  • Knee involvement has a variable prognosis. Some people improve, some remain the same, and some have progressively worsening OA.

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