Home / Conditions / Knee osteoarthritis
The smooth cartilage lining the knee gradually wears thin, and the joint becomes painful and stiff. It is the commonest reason for a painful knee after fifty. The wear cannot be reversed, but most people manage it well for years before surgery is ever worth considering.
Knee arthritis progresses slowly, over years, and what helps depends on the stage. Most people are at the early or moderate stage, where the knee is managed rather than operated on.
| Early | Moderate | Advanced | |
|---|---|---|---|
| What you notice | Stiffness after sitting, an ache after activity | Pain walking and on stairs, swelling at times | Pain at rest and at night, the knee may bow |
| What the X-ray shows | Little, or nothing obvious | The joint space narrowing, small bone spurs | Bone close to or on bone |
| What usually helps | Exercise, weight, and pain relief when needed | The same, plus a brace or an injection | If the rest has stopped working, a knee replacement |
| Surgery? | No | Rarely | Worth considering |
The X-ray and the pain do not always match. Some knees look badly worn on X-ray and hurt little; others look mild and hurt a lot. Treatment follows how the knee is affecting your life, not the picture alone — which is why nobody should be told they need a replacement on the strength of an X-ray by itself.
The ends of the thigh bone and shin bone are covered in smooth cartilage that lets them glide. In osteoarthritis that layer thins and roughens, the gap between the bones narrows, and the bone edges grow small spurs.
What a picture cannot show is why it hurts. Cartilage itself has no nerves, so the pain comes from the bone beneath it, the joint lining and the tissues around it. That is part of why the X-ray and the pain can disagree.
It also explains why the inner side of the knee usually wears first: more of your weight passes through it with every step. When the wear is confined to that side, a brace that shifts the load outwards can help, and a partial replacement of just that side is sometimes possible.
Treatment builds up in steps, and most people never reach the last one. The early steps are not a waiting room for surgery — for many knees they are the whole answer.
Strengthening the thigh muscles supports the knee and reduces pain, and it is the best-supported treatment short of surgery. Keep moving: walking, cycling and swimming help, and resting the knee for long periods tends to make it stiffer and weaker, not better.
Losing even a modest amount of weight makes a real difference, because each kilogram lost takes several kilograms of load off the knee with every step. Swapping high-impact activity for lower-impact exercise protects the joint without stopping you moving.
A brace that shifts load away from the worn side helps some knees. A steroid injection can ease a flare, though the relief usually lasts weeks rather than months. Lubricating injections are also used, but the evidence for them is mixed. Pain relief has its place, used to keep you active rather than instead of it.
When pain limits walking, sleep or daily life despite all of the above, a knee replacement is worth considering — partial where the wear is confined to one side, total where it is not. A keyhole “washout” of an arthritic knee, by contrast, has not been shown to help and is not offered for osteoarthritis alone.
Knee osteoarthritis here is seen by Dr Kelvin Tan Guoping, an orthopaedic surgeon whose subspecialty is hip and knee. He is a Fellow of the Royal College of Surgeons of Edinburgh, holds a Master of Medicine in orthopaedics, and is an Adjunct Assistant Professor at NUS. He consults in English, Mandarin, Teochew and Hokkien.
The worn cartilage does not grow back. But the pain and stiffness can very often be improved a great deal, and many people keep a knee that works well for years with exercise, weight management and the right pain relief.
Usually not. Stronger muscles support the knee and reduce pain, and resting it for long periods tends to make it stiffer. Choose lower-impact exercise, and ease off only if a particular activity leaves it much worse the next day.
A steroid injection can calm a flare, typically for weeks rather than months. Lubricating injections help some people, but the evidence is mixed. Neither changes the wear itself, so they work best alongside exercise rather than instead of it.
No. Many people with knee osteoarthritis never need one. A replacement is considered only when pain limits daily life despite everything else, and the decision is yours to make with the full picture.
Often, over time, osteoarthritis affects both knees, unless it followed an injury or a problem in just one. The same measures — strength, weight and staying active — help protect both.
No. Bring any knee X-rays you have, ideally standing ones, and a sense of what the knee is stopping you from doing.
Bring any X-rays, and a sense of what the knee is stopping you from doing. That shapes the plan more than the X-ray does.
