Unicompartmental knee replacement at Spire Harpenden Hospital

In some types of arthritis of the knee, only the medial (inside) part of the joint is affected. In this situation it is possible to replace the damaged part of the knee without resorting to a total knee replacement.

Initially, arthritis can be treated with painkillers, anti-inflammatories, physiotherapy and, in the earlier stages, arthroscopy (keyhole surgery) but as the knee progressively wears the only long-term treatment is to replace the damaged part of the joint.

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Our consultants have high standards to meet, often holding specialist NHS posts and delivering expertise in complex sub-specialty surgeries. Many of our consultants have international reputations for their research in their specialised field.

You will have a formal consultation with a healthcare professional. During this time you will be able to explain your medical history, symptoms and raise any concerns that you might have.

We will also discuss with you whether any further diagnostic tests, such as scans or blood tests, are needed. Any additional costs will be discussed before further tests are carried out.

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For more information on visiting hours, our food, what to pack if you're staying with us, parking and all those other important practicalities, please visit our patient information pages.

Our dedicated team will also give you tailored advice to follow in the run up to your visit.

The surgery involves removing a very small thickness of damaged bone from the inside part of the knee. Much less bone is removed than in a total knee replacement and only from one side of the knee. The partial knee replacement fits inside this prepared space and is fixed to the bone with cement.

The operation takes about an hour and involves an 8cm incision on the medial (inner) side of the kneecap. This small incision does not involve cutting any muscle or tendons (as with a total knee replacement), thus enabling quicker recovery from surgery.

The unicompartmental knee replacement comes in three parts. The femoral component is made of metal, is curved and highly polished. The tibial component is made of the same metal and has a flat upper surface. A plastic component, which is curved on the top and flat on the underside, sits on the flat tibial surface and can slide backwards and forwards. This mimics the meniscal cartilage in the normal knee. The upper part of this plastic insert articulates with the femoral component. This type of knee replacement is called a meniscal bearing and has the advantage of sharing the load through the knee over a large surface area, which helps to reduce wear and hence make the knee replacement last longer.

The day after the operation your exercise regime begins. With the aid of a physiotherapist you will get out of bed and begin to exercise your new knee replacement. With perseverance, you should be able to climb stairs by day 2 or 3 and go home the following day.

You will need to continue attending physiotherapy as an outpatient.  For most people it will take around 4 weeks to be walking reasonably. After three months you should be able to walk well without pain, climb stairs (leading with your operated leg) and be capable of a range of movement with your new knee from 0 degrees to at least 120 degrees.

We are committed to delivering excellent individual care and customer service across our network of hospitals, clinics and specialist care centres around the UK. Our dedicated and highly trained team aim to achieve consistently excellent results. For us it's more than just treating patients, it's about looking after people.

Important to note

The treatment described on this page may be adapted to meet your individual needs, so it's important to follow your healthcare professional's advice and raise any questions that you may have with them.