Partial knee replacement: who it suits, risks and recovery

The knee has three compartments: the inner side, the outer side and the joint behind the kneecap. When arthritis wears out only one of them, a partial replacement can swap that area for metal and plastic and keep the rest of your own knee, including the ligaments.

It is not suitable if arthritis is widespread, if the ligaments are not working, or if the knee is badly stiff or deformed. NHS guidance describes it as a smaller operation with a faster recovery than a total replacement.

Before any knee replacement, the trust leaflet expects non-surgical measures to have been tried: medicines, weight loss where relevant, physiotherapy, exercise and walking aids.

Doing the basic leg exercises before surgery makes the early days easier, and the teams that write these leaflets encourage it. At pre-assessment you will be checked for heart, lung and kidney problems, have swabs and bloods, and be told when to stop eating and drinking.

Set up the house before you go in: a firm chair with arms, a clear path, a place to sit with the leg up, and any help you will need with shopping or stairs.

• Ask which of your regular medicines to continue.

• Stop smoking if you can: it affects wound healing and infection risk.

• Pack loose clothing, supportive shoes and your walking aid if you already use one.

The surgeon replaces the worn surfaces of the thigh bone and shin bone on one side with metal parts and a plastic spacer between them, leaving the opposite side alone. NHS information gives about one to two hours for knee replacement surgery generally.

You are encouraged to start moving early, often on the day of surgery. Staying in hospital may be short: the Worcestershire leaflet says leaving the same day is possible, though some people stay longer. Going home depends on walking safely, managing stairs and having acceptable pain control.

The trust leaflet lists blood clots, infection, lasting pain or stiffness, nerve or blood vessel injury, and the possibility of needing to convert to a total replacement. It gives a 6-7% revision rate at 10 years. NHS pages describe knee-replacement complications as uncommon for most people without giving numbers.

Because the rest of the knee is retained, arthritis can progress in the other compartments over time, which is one reason a later conversion may be needed.

Worcestershire gives full recovery in about six to twelve weeks, a return to hobbies at six to ten weeks, stitch removal around 14 days and compression stockings for at least six weeks. NHS guidance says return to work after knee replacement is often around six to twelve weeks, and discharge usually one to four days after surgery.

These ranges are typical and vary. Your surgeon and physiotherapist override any page, including this one.

• A swollen, hard, hot, red or tender calf: contact your GP or NHS 111 straight away.

• Spreading redness, discharge or fever around the wound.

• Chest pain or sudden breathlessness: call 999.

• A knee that suddenly cannot bear weight or feels unstable.

• Am I a good candidate for a partial replacement, and what is the chance you will switch to a total one on the day?

• How many of these operations do you do each year?

• What would revision involve if it were needed?

• How will my physiotherapy be arranged?

Both routes use similar implants and techniques. Differences lie in waiting times, choice of surgeon and the extent of aftercare. Some surgeons do more partial replacements than others, so asking about experience is reasonable in either setting.