Knee Replacement: What Actually Happens, Step by Step

Knee replacement (also called knee arthroplasty) is usually recommended when the cartilage in the knee has worn down enough that pain, stiffness, or swelling are limiting everyday activities — walking, climbing stairs, or even sleeping — despite a fair trial of medication, injections, and physiotherapy.

In the surgery itself, the damaged surfaces of the joint are resurfaced with smooth metal and plastic components — not the whole leg, just the worn parts of the joint. Modern robotic and computer-navigation-assisted techniques allow the implant to be positioned with a high degree of precision, which can mean a more natural-feeling knee and a more predictable recovery.

Most patients are up and walking, with support, within a day of surgery. A structured physiotherapy plan over the following weeks focuses on regaining bend, straightening the knee fully, and rebuilding the muscle strength around the joint — this rehab work matters just as much as the surgery itself for a good long-term result.

Not everyone with knee arthritis needs a replacement. It's usually considered once conservative treatment genuinely isn't keeping up with the pain — and even then, the decision is made together, based on your goals and how the joint is actually affecting your life.