Osteoarthritis: What You Need to Know

At a Glance

About Osteoarthritis

Osteoarthritis is the most common joint disease worldwide and in South Africa. It is a progressive, degenerative condition affecting articular cartilage — the smooth tissue that covers the ends of bones within joints. As cartilage breaks down, bone surfaces make direct contact, causing pain, stiffness, and reduced range of motion. Unlike rheumatoid arthritis, OA is not primarily an inflammatory or autoimmune disease — it is mechanical and degenerative in origin, though inflammatory changes occur secondary to cartilage breakdown.

OA affects any joint but most commonly impacts the knees, hips, hands (particularly the base of the thumb and distal interphalangeal joints), and the spine (facet joints). Knee and hip OA are the primary drivers of joint replacement surgery in South Africa.

Risk Factors

• Age: The strongest risk factor. OA is rare before 40; highly prevalent after 65.
• Obesity: For every kilogram of body weight, the force on each knee is multiplied 3–6 times during walking. Weight loss is the most effective intervention for knee OA.
• Prior joint injury: Post-traumatic OA develops years after a significant joint injury. Young athletes with ACL tears carry lifetime knee OA risk.
• Sex: Women develop OA more commonly than men, particularly after menopause. Hormonal changes are implicated.
• Occupation: Physically demanding work with repetitive joint loading (farming, construction, nursing) accelerates OA.
• Joint dysplasia: Developmental hip dysplasia significantly increases lifetime risk of hip OA — elevated prevalence in certain SA populations.

Radiological Grading — Kellgren-Lawrence Scale

OA severity on X-ray is graded using the Kellgren-Lawrence (KL) scale: - KL 0: Normal - KL 1: Doubtful — minimal joint space narrowing; possible osteophytes - KL 2: Mild — definite osteophytes, possible narrowing - KL 3: Moderate — multiple osteophytes, definite narrowing, some sclerosis - KL 4: Severe — large osteophytes, marked narrowing, severe sclerosis, possible bony deformity

Surgery is typically considered from KL 3–4 when conservative management has failed.

Treatment Pathway

Step 1 — Non-Pharmacological Management

The most evidence-based interventions for OA are weight loss and exercise — not medication. For knee OA specifically, every 1kg of weight lost reduces knee joint load by 3–6kg per step. This is more effective for pain and function than most analgesics.

• Physiotherapy: Quadriceps strengthening is the single most evidence-based intervention for knee OA. Hip abductor strengthening for hip OA. Supervised exercise 3x/week is the target.
• Walking aids and assistive devices: Reduces joint loading and fall risk.
• Heat/cold therapy: Symptomatic relief.
• Occupational therapy: Adaptive strategies for daily activities.

Step 2 — Pharmacological Management

Topical agents (first-line): - Topical diclofenac gel: Effective for knee OA with minimal systemic absorption. Preferred over oral NSAIDs in older patients or those with renal or cardiovascular comorbidities.

Oral analgesics: - Paracetamol: First-line oral analgesic. Safe at therapeutic doses. Less effective than NSAIDs but preferred in frail or elderly patients. ~R60/month. - NSAIDs (ibuprofen, diclofenac, meloxicam, celecoxib): More effective than paracetamol for OA pain. Key risks: gastrointestinal (ulcers, GI bleeding), renal impairment, and cardiovascular effects. Selective COX-2 inhibitor celecoxib (~R350/month) has lower GI risk than non-selective NSAIDs. Add a proton pump inhibitor (omeprazole) when using oral NSAIDs in patients over 65 or with GI risk factors.

NSAID caution in comorbid conditions: Many OA patients also have hypertension and/or chronic renal disease. NSAIDs worsen blood pressure control and are nephrotoxic — they should be used at the lowest effective dose for the shortest duration, or avoided entirely in patients with CRD stage 3+.

Step 3 — Intra-Articular Injections

• Corticosteroid injections (triamcinolone): Rapid pain relief; effect lasts weeks to months. Maximum ~3–4 injections per year to avoid cartilage damage. ~R400 per injection (procedure fee additional).
• Hyaluronic acid viscosupplementation: Injected into the joint to supplement the natural hyaluronic acid in synovial fluid. More expensive (~R2,000 per course); evidence is mixed — some trials show benefit, systematic reviews less convincing.

Step 4 — Joint Replacement Surgery

When conservative management fails to control pain and maintain function, total joint replacement is the most effective intervention: - Total knee replacement (TKR): Removes the damaged joint surfaces and replaces them with metal and polyethylene prosthetic components. Highly effective — > 90% patient satisfaction at 10 years. Estimated cost: R120,000–R180,000 at a private hospital. - Total hip replacement (THR): Replaces the femoral head and acetabulum. Also very effective. Estimated cost: R130,000–R200,000.

Joint replacement is the definitive treatment for end-stage OA. It does not reverse OA — it replaces the joint entirely. Implants typically last 15–25 years, meaning younger patients (< 60) may require revision surgery.

Annual Cost Estimates

The Talk to Eldon Angle

OA itself does not drive scheme or plan selection. Conservative management costs R1,500–R12,000/year and is managed from d2d benefit and GP/specialist consultations. The financial decision point is joint replacement. Orthopaedic surgeons routinely bill above scheme rate — the gap between what a private orthopaedic surgeon charges and what the scheme pays can be R20,000–R60,000 for a single TKR. Gap cover with surgical sub-limit protection is the primary financial planning tool for OA patients who are joint replacement candidates. The advice is binary: before surgical candidacy, OA does not change the recommendation; at surgical candidacy, gap cover becomes important.

Sources

1. SA Rheumatology Association OA Clinical Guidelines 2023.
2. OARSI Guidelines for hip and knee OA management. Osteoarthritis Cartilage, 2024.
3. Kellgren JH, Lawrence JS. Radiological assessment of osteoarthritis. Ann Rheum Dis, 1957.

Ready to check your OA cover, especially if joint replacement is on the horizon? Run your AURA medical aid check