Arthritis is not one disease — it's a general term for inflammation and damage within a joint, and the hip and knee are two of the joints affected most often. Understanding what's actually happening inside your joint is the first step to choosing the right treatment.
What is happening inside an arthritic joint?
Every joint is lined with smooth cartilage that lets bones glide against each other with almost no friction. In osteoarthritis — by far the most common type affecting the hip and knee — this cartilage gradually thins and roughens. As the cushioning wears away, bone can eventually rub against bone, which is what produces the deep, grinding pain patients describe on movement.
Rheumatoid arthritis works differently. It's an autoimmune condition where the body's immune system mistakenly attacks the joint lining (the synovium), causing inflammation that can damage cartilage and bone from the inside out over time. It tends to affect multiple joints symmetrically and often needs to be managed jointly with a rheumatologist alongside orthopaedic care.
The four stages of osteoarthritis
- Stage 1 (Minor): Small bone spurs, minimal cartilage wear. Usually no pain.
- Stage 2 (Mild): Visible bone spurs on X-ray, joint space still largely preserved. Occasional stiffness after rest, mild pain after long activity.
- Stage 3 (Moderate): Clear cartilage erosion, narrowed joint space. Pain during normal activity, stiffness after sitting, occasional swelling.
- Stage 4 (Severe): Cartilage largely gone, bone-on-bone contact. Significant pain even at rest, major restriction of movement.
Treatment by stage
Early to moderate arthritis
Most patients start here, and most don't need surgery at this stage. Options include:
- Activity and weight management to reduce load through the joint
- Physiotherapy to strengthen the muscles supporting the joint
- Anti-inflammatory medication, used carefully and for limited periods
- Corticosteroid or viscosupplementation injections to manage flares
- Bracing or walking aids to offload the joint during activity
Advanced arthritis
When non-surgical measures stop giving meaningful relief — when pain limits sleep, walking, or basic daily tasks — joint replacement becomes the conversation. This isn't a failure of the non-surgical approach; it's simply the point where the joint's own surfaces are too worn to restore with anything short of resurfacing them.
How joint replacement is decided
The decision to proceed with hip or knee replacement is based on three things together: how much the joint is worn on imaging, how much it's limiting your daily life, and whether non-surgical options have been genuinely tried. Age is a factor in planning implant longevity, but is rarely, by itself, a reason to delay or rush surgery.