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Indications for varus and valgus osteotomy (part 2a of a course on realignment osteotomy)

There are three different types of patient that would be suitable for either a var-ising or a valg-ising osteotomy - and it is a spectrum.

The spectrum includes -

1. Mild degrees of joint surface damage within one compartment

Dr (mr) adrian wilson with patient

At one end of the spectrum may be someone who has pain following the resection of some or all of their shock-absorber (meniscal) cartilage, as well as some joint surface damage which may be relatively minor but is significant enough to cause medial or lateral knee pain. This kind of patient is most likely to benefit from an osteotomy. If they seek surgical help relatively early the degree of wear and tear within the knee may be relatively mild. When the osteotomy is preformed early, the weight-bearing load can be transferred from the problematic compartment to the good compartment and that may be the last time the patient needs to have any surgery on their knee.

That’s a very different problem to the pictures that we saw in part 1 of the bow legs and the knock knees.

In these early cases the signs might be very subtle, ie the patient may be in slight varus (bow-legged) alignment, and it is only when you do the long leg X-rays that you determine the true extent of their mal-alignment.

For instance, if you have a young patient with ongoing knee pain that hasn’t settled with conservative measures, or even arthroscopic chondral or meniscal surgery, then by carrying out an osteotomy, the painful knee compartment can be offloaded, thereby significantly improving their symptoms.

A knee osteotomy is a good pain relieving procedure for the younger, fit patient with localised knee arthritis. It allows that patient to keep their native knee and delay the need for knee replacement.

2. Protecting fragile surgery

The next major group includes patients who need advanced knee surgery and require the best possible environment for that surgery to work. For instance, if the patient has cartilage transplantation surgery, a microfracture, or a meniscal transplantation, and their knee is not well aligned, the surgery has a lower chance of success. So, getting the alignment right is crucial - either for straight-forward knee pain or when creating the best environment for other surgical procedures to succeed. Performing a cartilage transplant procedure in the medial compartment of a patient with varus mal-alignment (who already has very excessive forces going through their medial compartment) is unlikely to work. 

3. Osteotomy as part of management of an unstable knee

Dr (mr) adrian wilson and patient

Another important but less common indication for osteotomy surgery is in the very unstable knee. Here ligament surgery alone may not be sufficient and the knee may require realignment surgery to allow the required ligament reconstruction to work. The most common problem in this group of patients is severe valgus instability - where there may be a lateral collateral ligament deficiency or following a big posterolateral corner injury when the patient develops a varus thrust. Correcting the alignment from varus to slightly valgus would significantly increase the chance of the lateral/postero-lateral reconstruction working.

When looking at lateral (side-on) x-rays of the knee, the incline at the top of the tibia (tibial slope) can be calculated. If this slope is unusually steep, the femur will tend to roll off the back of the tibia and tends to ‘slide down the hill’. This would be very detrimental in a patient with ACL deficiency. So if a patient is ACL deficient, flattening the slope would improve their knee stability, as the tibia would be less likely to slide forwards on to the femur. In fact, the first surgeons that realised the importance of tibial slope were the veterinary surgeons who noted that just performing an osteotomy to flatten the tibial slope would more than stabilise the knees of ACL deficient greyhounds, making ligament reconstruction itself unnecessary. 

The reverse is true in PCL deficient patients (in whom the tibia has a tendency to go backwards under the femur when weight-bearing), who can regain much of their knee stability from an increase in their tibial slope alone (which shifts the tibia forward), without reconstructing the ligament itself. 

So the classic patient that you see is someone who presents in their 40s,  20 years following an untreated ACL rupture. As their knee has been ACL deficient and unstable for many years, they tend to have significant damage to their medial compartment, including meniscal and chondral/cartilage wear, which is now causing pain. So you’ve got to address two issues here. Firstly, you’ve got to offload the medial compartment and you do that by shifting the joint line in the coronal plane, into the healthy lateral compartment. Secondly, at the same time you can flatten the tibial slope in the side-on (sagittal) plane, thereby decreasing the tendency of the tibia to shift forward and stabilising the knee. So for an ACL deficient knee a flat slope is desirable and for a PCL deficient knee a steeper tibial slope is required. And by doing those relatively simple manoeuvres when you are actually carrying out your osteotomy you can radically improve the stability within the knee.

Bow legs with ligament damage

 

The patient on the left is a really good example.  He is a 48 year old businessman and he has been really sporty all his life. He ruptured both his ACL ligaments and has had failed attempts to reconstruct his ACLs.  He soldiered on to the point where he ground to a halt because of the arthritis that had developed in his knees as a result of ACL deficiency and instability. On his right side (on the left of the photo) he had a closing wedge HTO which I did for him 3 years ago – that is why it looks as if it is in slight valgus. At the time I wanted him to have his left knee done, but it wasn’t an ideal time for him to have further surgery as had just had a small child. So he has come back to me now three years later and said “Look, I am absolutely delighted with my right knee, I certainly don’t need anything further doing on it ligament wise you sorted that out – as well as making my knee stable you got rid of the pain, but what are you going to do about my left knee?” We call this a ‘windswept’ appearance – as we are looking at him his right knee is slightly valgus (left of photo) while his left knee (right of photo) is very varus. So what he needs is to have an osteotomy of his left knee to correct that – and again and I think what we will do is to repeat what we did before (as he has done so well) and just carry out the osteotomy bearing in mind his ACL deficiency would benefit from a flatter tibial slope at the time of the surgery. If he continues to have knee instability post osteotomy relatively it will be relatively straightforward to do an ACL reconstruction at some later stage. His pictures are really quite dramatic.

4. Terrible arthritis like extremes of bow legs and knock knees

This operation used to be done for people like the gentleman in Part 1a whose legs are very bow-legged and whose X-ray shows very arthritic knees medially.

Now, it used to be said that osteotomy was done for these patients and they didn’t do well – and they didn’t do well for all the reasons I have said before – the technique, the fixation device, the post-operative rehabilitation, the planning. Actually these patients now get very good results with osteotomy, and it is a very good alternative to a knee replacement but the indications for surgery have to be met. It was thought that osteotomy didn't work in severely arthritic knees,  and that you put patients through a big operation and bought them 2 or 3 years at best. In fact we are now seeing very good 5 and 10 year results with people with severely arthritic knees localised to one compartment who are having this operation.

In the severely arthritic patient like these, the aim of osteotomy surgery nowdays is to buy time and in most cases we would expect more than 10 years before a knee replacement is then required. In patients with less severe arthritis it may be the only treatment needed, putting off knee replacement altogether. Osteotomy should always be considered as an option in younger patients with localised knee arthritis.

With the digital pre-operative planning, improved surgical techniques and revolutionary new plates, osteotomy has become a highly successful and well-established treatment for the painful arthritic knee.

Updated: 02 May, 2013
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