Do I need a knee replacement yet?

The X-ray does not decide it

Picture two patients. One has an X-ray with almost no joint space left, walks into clinic without a stick and manages the stairs at home. The other has moderate changes on the film and has not slept through the night in months. The second is much closer to a knee replacement than the first.

An X-ray shows how much cartilage has gone and where. It cannot show how much the knee hurts, and the two often disagree. I use the film to plan, and what you tell me about your days and nights to decide.

Signs it may be time

One of these on its own seldom tips the balance. Three or four together usually do.

• Pain at night or at rest. Pain on walking is what arthritis does. Pain that wakes you, or that is there while you sit, means the knee has gone past what simpler treatment can settle.
• A shrinking world. You plan outings around where you can sit down, you have stopped walking to the market or the gurdwara, or you have handed over jobs you used to do yourself.
• Stairs and chairs. Getting up from a low chair, using an Indian-style toilet or climbing stairs has become the hardest part of the day.
• The leg is changing shape. It bows further each year, or the knee will no longer straighten fully.
• The simpler treatments have had a fair try and have stopped working, or now help only for a few weeks at a time.

What to try first

Before an operation is discussed, most knees deserve a proper go at the treatments below. Proper means a few months, with someone checking how the exercises are being done. A fortnight of videos does not count.

• Strengthening the thigh. The quadriceps takes load off the knee with every step, and stronger thigh muscles reduce arthritic pain. Exercise has the best evidence of anything on this list.
• Weight. Every kilogram you lose takes several off the knee each time you take a step. Five kilograms is a difference people notice.
• Painkillers, used sensibly. An anti-inflammatory gel rubbed into the knee is a good start. Anti-inflammatory tablets help more but need care with the stomach, kidneys and blood pressure, so take them on advice and not for months unsupervised. Paracetamol on its own helps little.
• A steroid injection can calm a bad flare for weeks to a few months. It is for getting through a bad spell, and it is not repeated every few weeks.
• A stick in the opposite hand. It takes a surprising amount of weight off the knee.

No injection, oil, supplement or machine regrows cartilage in an arthritic knee. Some of them ease pain for a while. If you are offered one as a cure, ask what it is expected to do and for how long.

When the whole knee is not worn

Not every arthritic knee needs a full replacement. Two other operations suit particular knees, and they should be on the table before you agree to one.

• A partial knee replacement resurfaces only the worn side, when the rest of the knee and its ligaments are sound. Roughly one knee in four that needs replacing is suitable. It is a smaller operation, and the knee often feels more like your own afterwards.
• A high tibial osteotomy straightens a bowed leg so your weight passes through the healthier side of the knee. It suits a younger, active patient, roughly under fifty-five, and can put a replacement off for a decade or more.

Standing X-rays and an examination of the ligaments decide which of these your knee could have. If the answer is a full replacement, I will show you on your own X-rays why.

Does waiting cost anything?

For most people, no. A knee replaced in two years does as well as one replaced now, in most cases, and arthritis seldom becomes an emergency. That should take some pressure off the decision.

There are exceptions, and they are why a knee that is being watched should still be seen from time to time:

• A leg that bows further each year. The more it bends, the tighter the ligaments on the inner side become and the harder the correction is.
• A knee losing the ability to straighten. A knee that cannot straighten before the operation is harder to get straight after it.
• Thigh muscles wasting because the leg is being spared. Recovery depends on those muscles, and keeping them now is easier than rebuilding them later.
• Your general health. If diabetes, heart trouble or weight are slowly getting worse, the operation may be safer now than in five years.

Age by itself is a reason neither to wait nor to hurry. A fit seventy-five-year-old can do very well. A forty-five-year-old will probably wear out a first knee and need it redone, so the alternatives above are tried harder first.

How I approach it

Knee replacement was the main subject of my arthroplasty fellowship, at Lilavati, Sir HN Reliance and Breach Candy Hospitals in Mumbai and at Max Superspeciality Hospital, Mohali. Plenty of the patients I see about an arthritic knee leave without a date for surgery. They leave with a plan for the next few months and a clear idea of what would change the answer.

When it is time, it is generally obvious to both of us. If you have been told you need a replacement and are not sure, a second opinion before a joint replacement explains what to bring and what to ask. If you are weighing up the technique, what a robot can and cannot do goes through it.

Bring your most recent standing X-rays, a list of what you have tried and for roughly how long, and your medicines. What happens at your first consultation covers the rest.

Further reading

• NICE: Osteoarthritis in over 16s, diagnosis and management (NG226), 2022. The UK guideline, including what to try before surgery.
• NHS: Osteoarthritis.
• NHS: Knee replacement.
• American Academy of Orthopaedic Surgeons, OrthoInfo: Unicompartmental knee replacement.

Common questions