Knee Osteotomy: The Bone-Realigning Operation That Buys You Years

A knee osteotomy cuts and reshapes the shinbone or thighbone so that weight passes through the healthier side of the knee instead of the worn side, which can relieve pain and delay a replacement for several years. It is used when osteoarthritis has damaged just one side of the joint, and it works by correcting the alignment that put the extra load there in the first place¹.

I was never a candidate for this operation. By the time anyone was discussing surgery with me I was in my sixties, the wear was not confined to one side, and a replacement was the sensible answer. But I have sat in enough waiting rooms next to people in their forties and fifties, being told they were too young for a new knee and given no clear idea what else existed, to think this deserves a proper explanation rather than a passing mention. This guide, checked by a consultant orthopaedic surgeon, covers what an osteotomy is, who it suits, what the operation and recovery involve, and its honest trade-offs against a replacement.

What the operation does

Osteoarthritis often develops when the bones of the knee and leg do not line up well. That misalignment puts extra stress through either the inner (medial) or outer (lateral) side of the knee, and over time the extra pressure wears away the smooth articular cartilage protecting the bones¹. If you have bow legs, the load is concentrated on the inner side; if you are knock-kneed, on the outer.

An osteotomy attacks that mechanism directly. It has three goals: to transfer weight from the arthritic part of the knee to a healthier area, to correct the poor alignment, and to prolong the life of your own joint¹. Most osteotomies for knee arthritis are done on the shinbone to correct a bow-legged alignment overloading the inner compartment, an operation known as a high tibial osteotomy. The equivalent on the thighbone is usually done for a knock-kneed alignment, and the two can be combined.

Mechanically it is a wedge. The surgeon either opens a wedge on the inner side of the shinbone, filling it with bone graft or synthetic bone, or removes a wedge from the outer side and closes the gap¹. Either way the leg straightens, more load passes through the healthy side, and the worn side gets more space and less pressure. Our guide to bow legs, knock knees and knee arthritis explains the alignment side of this in more detail.

Who it suits, and who it does not

This is a narrow operation with fairly specific criteria, which is the single most common reason people are disappointed by the answer. Knee osteotomy is most effective for thin, active patients under the age of 60. Good candidates have pain on only one side of the knee, no pain under the kneecap, and knee pain brought on mostly by activity or by standing for a long period. They also need to be able to fully straighten the knee and bend it to at least 90 degrees before surgery¹.

People with rheumatoid arthritis are not good candidates, because the disease affects the whole joint lining rather than one overloaded compartment¹. If your arthritis is inflammatory rather than wear-driven, the answer lies elsewhere, as we explain in rheumatoid arthritis and the knee.

It is also worth knowing that osteotomy has become less common than it once was, because results from partial and total knee replacement have been so successful. It remains an option for many patients, especially young, active adults with a localised problem and a visible deformity that can be corrected¹. That is not a slight on the operation. It is the reason your surgeon may not raise it unless you fit the description.

The operation and the recovery

A knee osteotomy operation typically lasts between 1 and 2 hours, under either a general or a spinal anaesthetic¹. The surgeon plans the size of the wedge in advance from carefully aligned X-rays, makes an incision at the front of the knee starting below the kneecap, cuts along guide wires with an oscillating saw, places or removes the wedge, and fixes everything with a plate and screws.

The recovery is where this operation asks more of you than a replacement does. Most people go home 1 to 2 days after an osteotomy, then need crutches for several weeks, sometimes with a brace or a cast protecting the knee, because the osteotomy needs time to heal and that takes roughly 6 weeks¹. Your surgeon decides when weight can go through the leg, usually after a follow-up X-ray confirms the bone is uniting. Physiotherapy then works on range of movement and strength, and full activities are usually possible 3 to 6 months after surgery¹.

The risks are low but they are real: infection, blood clots, stiffness of the knee joint, injury to blood vessels or nerves, and failure of the osteotomy to heal, with a second operation occasionally needed if the bone does not unite¹. That last one has no equivalent in joint replacement surgery, and it is the risk worth asking about specifically, particularly if you smoke.

Osteotomy against a partial or total replacement

The honest comparison has losses on both sides. Pain relief is not as predictable after an osteotomy as after a partial or total knee replacement, and the recovery is longer and more difficult because you cannot put full weight through the leg straight away¹. Against that, once an osteotomy has healed there are no restrictions on physical activity, including high-impact exercise, which is not something anyone will say to you after a joint replacement.

The nearest surgical neighbour is a partial replacement, which resurfaces only the one damaged compartment and keeps the healthy bone and ligaments². The choice between them tends to turn on age, activity and how much deformity there is: a partial replacement is a more predictable pain solution, an osteotomy keeps your own joint surfaces and your own ligaments. We set the replacement options side by side in partial versus total knee replacement.

For most people, osteotomy relieves pain and delays the progression of arthritis in the knee, and it can allow a younger patient to lead an active life for many years. Many will still need a total knee replacement in the end; the osteotomy is an effective way to delay it¹. In some cases, having had one makes that later replacement more technically challenging, which is a fair thing to put to your surgeon directly.

Where it fits in the plan

An osteotomy does not replace the ordinary work of managing an arthritic knee. NICE guidance puts exercise and, where relevant, weight management at the centre of treatment for knee osteoarthritis for everyone, whatever surgery may or may not be coming³, and the joint keeps needing that afterwards. The condition itself is progressive wear of the joint surface, and no operation changes that fact about the rest of the joint⁴.

What an osteotomy does buy is time in your own knee, at an age when that is worth a great deal. If you are in your forties or fifties and being told you are too young for a replacement, this is one of the specific questions to raise: whether your wear is confined to one compartment, whether your alignment is correctable, and whether you meet the criteria. Our guides to alternatives to knee replacement, knee replacement for younger patients and the questions to ask your knee surgeon will help you have that conversation properly rather than leaving with a vague “not yet”. Whether an osteotomy is right for your knee is a judgement that needs your X-rays, your examination and your surgeon, not an article.