When is a knee replacement needed?
Written in association with:
Orthopaedic surgeon
Published: 22/01/2025
Edited by: Jessica Wise
A knee replacement is the surgical treatment for advanced osteoarthritis. It resurfaces damaged bone and cartilage in the knees with metal and plastic. In this article, Mr Hersh Deo, a consultant orthopaedic surgeon, explains why and how a knee replacement surgery is performed.
What are the symptoms of knee arthritis?
Osteoarthritis in any joint occurs when the normally smooth (articular) cartilage which covers the bone ends, wears away. This leaves the underlying bone exposed. When bone touches bone in a joint, this is known as advanced osteoarthritis (OA).
Symptoms of OA can get worse slowly over months and years and include:
Pain, especially when weight bearing and at night. Walking distance is reduced. Stiffness, when the movements become restricted Swelling, when the knee swells after activity Deformity, when the shape of the leg starts to change (e.g. bowing or knock knee)
When is a knee replacement needed?
There are many treatment options to treat early OA and these should be tried first before having a total knee replacement (TKR). These include:
Oral/topical painkillers Physiotherapy Knee brace Walking aids Knee injections Keyhole surgeryIf the pain or deformity gets worse despite these interventions and your scans show bone touching bone, then a knee replacement is required.
Who can get a knee replacement and what kinds are there?
You need to be reasonably fit and well and be motivated to mobilise after the operation. You will be seen by an anaesthetist at a pre-assessment clinic.
There are 2 types of knee replacement:
Partial knee replacement (also known as half knee replacement or unicompartment knee replacement (UKR))
The knee has 3 compartments. If 1 compartment becomes arthritic and the other 2 are normal — then instead of replacing the whole knee, just the affected compartment can be replaced. This leaves the internal structures and the normal compartments of the knee alone meaning that the knee feels more natural after the operation. The recovery and complications are less than that of a TKR.
Total knee replacement (TKR)
If 2 or more compartments are arthritic, then a total knee replacement is indicated. All of the joint surfaces are resurfaced, which means no more bone on bone when moving or using the knee — which improves pain, stiffness, deformity and long-term function.
What happens during knee replacement surgery?
A spinal anaesthetic with sedation is the best option. You can discuss this with the anaesthetist at the pre-assessment clinic and on the day of surgery.
The surgeon makes one long incision down the front of the knee. The damaged sections of bone are measured, removed and reshaped to fit the implants. These are made of metal or ceramic and are cemented onto the bone ends and compressed. A high-density plastic spacer is inserted between the metal implants. I will always resurface the underneath of the kneecap as well.
The layers are closed and bandaged.
What are the complications of knee replacement surgery?
Complications are rare after knee replacement. Commonest are:
Wound infection (1%) Blood clots (deep vein thrombosis (DVT)) Stiffness Damage to nerves and blood vessels
What is the recovery like after a knee replacement?
The spinal anaesthetic combined with local anaesthetic put into the knee at the time of surgery helps greatly with post-operative pain. You will be given regular painkillers after the operation and some to take home. There are no restrictions after a knee replacement. You can put as much weight through it as pain allows and start walking with the help of the physiotherapist on the day of surgery. Your walking ability will improve each day. You will be given crutches or sticks to go home with. You should try to move it as much as possible to avoid stiffness. Ice packs or sleeves help to reduce pain and swelling after the operation. The knee takes about 6 weeks to heal up from the inside. You will be able to start getting back to normal activities like work and driving around this time. The swelling can take 3 months to settle. At 6 months the knee should be moving well with little to no pain. By a year, it should be fully healed.
If you are considering a knee replacement, consult with aMr Deo via his Top Doctors profile. For more information, please visit www.deo-orthopaedics.co.uk