Surgery of the Foot & Ankle

Mark S. Davies FRCS (Orth) Consultant Orthopaedic Surgeon, The London Foot & Ankle Centre at the Hospital of St John & St Elizabeth, London
Original: 01/02/2002
Reviewed: 17/04/2014
Next review due: 17/04/2017

Rheumatoid arthritis is a disease which affects 1-2% of the population. Approximately 15% of patients who have the disease will have pain and/or swelling affecting the feet as their first symptom. It is, contrary to popular belief, more common for the disease to first manifest itself in the form of foot problems than hand problems.

Rheumatoid arthritis is much more common in females than males and although it can develop at any age it most commonly presents between the ages of 40-60. This means that some patients with rheumatoid arthritis have the disease for well over half their life. During the progress of the disease up to 90% of patients will develop foot problems. This has major implications for mobility and even such mundane things as finding a pair of shoes to wear. The main problems with rheumatoid arthritis and foot involvement relate to pain, swelling and deformity. It does not take much pain, swelling or deformity to make it impossible to wear a shoe at all. However, unfortunately "rheumatoid feet" are often even more uncomfortable out of shoes than in shoes. 

Whenever a patient has a foot problem, whether or not it is associated with rheumatoid arthritis, there are realistically only five options as far as treatment is concerned.

These are: 
  • Ignore it
  • Modify footwear
  • Medication (tablets and/or injections)
  • Physiotherapy and
  • Surgery

As a general rule most rheumatoid patients have multiple joints that are painful and are often very stoical about their condition. The mainstay of management remains medical and there are many medications which can have a dramatic effect on the quality of life of these patients. These drugs are mainly good at suppressing inflammation and in doing so are good at alleviating pain. However, the inflammatory process can not be totally halted and when the disease process is aggressive joint damage will often follow. This leads to a different kind of pain, which relates to derangement of the joints. This is so-called mechanical pain i.e. pain that results from physical damage to the joint. Not surprisingly the weight-bearing joints of the lower limb are particularly prone to mechanical pain and, when affected, have a major effect on mobility. That is not to say that upper limb joint damage is not debilitating but it rarely affects mobility, unless of course crutches etc are being used.

Whilst the knee and the hip joints can be replaced with relative ease, it is not possible to replace all the joints of the foot. When the foot and/or ankle is affected by rheumatoid arthritis usually both feet are involved and multiple joints as well. Including the ankle there are 33 joints in a foot and only two of them lend themselves to joint replacement: the ankle and the big toe joint. This means that there are plenty of joints which can be the source of pain and are not suitable for replacement. In the hindfoot and the midfoot the mainstay of orthopaedic surgical treatment is fusion i.e. permanent joining of the two bones on either side of the joint. Unfortunately there is no such thing as bone glue and therefore achieving union i.e. solid fusion, involves holding the joint rigidly with screws (or less optimally with staples). The two bones then have to join together and this takes approximately 3 months. In many rheumatoid patients the bones are relatively soft, due to a combination of drugs (such as steroids) plus relative disuse. This all means that the foot has to be immobilised in a plaster of Paris for the three months and the patient may have to be non weight-bearing. If there is significant upper limb involvement this can make crutches almost impossible to use, so that for three months a wheelchair may be required, or the use of a K" trolley: www.walk-aid.co.uk/. If a patient's house does not lend itself to wheelchair access she/he may need to be hospitalised for the duration of cast immobilisation. Given that following any foot operation it takes a good six months to recover function, if both feet are operated upon consecutively it takes about a year to get over the surgery. It should be clear from the above that foot surgery is not to be entered into lightly.

For reasons that are not easily explained, foot surgery has been relatively neglected by orthopaedic surgeons until recently, particularly in the UK. Foot and ankle surgery however has developed enormously in the last 25 years, the main developments having come from America, and more recently France. So what can be done surgically for the affected foot and ankle? The answer is actually quite a lot, but it has to be carefully considered and carefully executed. If a joint is fused in an incorrect position it can have a devastating effect on the foot. As a general rule however, if a foot looks like a foot, it might work like a foot.

The foot can be divided into three main parts: the forefoot, the midfoot and the hindfoot i.e. the front part, the middle part and the back part. It is best to consider these parts of the foot individually.

The Fore-foot

If rheumatoid arthritis affects the forefoot the usual problem is deviation of the big toe associated with dislocation of the lesser toes. This means that the forefoot is broad and weight-bearing can be exceedingly painful. If footwear modification fails to make walking more comfortable, surgery alone can make a difference. If wearing trainers, soft cushioned shoes or custom-made shoes is still very painful, then serious consideration should be given to surgical correction. Conventionally, removing the metatarsal heads (the bony prominences in the ball of the foot) and fusion of the big toe can transform the quality of life of an affected patient. Needless to say this surgery has to be meticulously performed if it stands a chance of success. Although it leaves the big toe stiff and the other toes floppy, the pain relief can be spectacular. Although this kind of surgery does not cure the condition, it can relieve pain for many years and make the wearing of "off the shelf" shoes possible. There are some feet however which do not need such destructive surgery. If the rheumatoid process has not destroyed the joints of the toes, it is possible to preserve the joints and maintain good function. This surgery has been recently revolutionised by Louis Barouk in Bordeaux, France and Lowell Scott Weil from America. In my experience, correcting the big toe deformity however is less rewarding than fusing the big toe as there is often a rapid recurrence of the deformity following surgery. This is because the soft tissues in the rheumatoid foot are often very weak and therefore soft tissue procedures rapidly fail. However, in a young patient, it is still worth considering preserving the big toe joint as opposed to fusing it, accepting that if it does fail further surgery may be required to fuse the joint. Such surgery can be technically challenging and in some severe cases impossible, but it should be remembered that restoring anatomy is the single best way of preserving function in the long-term. It goes without saying that the "occasional" foot surgeon is more likely to be unfamiliar with these techniques and more likely to make an error of judgement or technical error than a dedicated foot and ankle surgeon.

Big toe joint replacement is a controversial area of foot and ankle surgery with some surgeons frequently carrying out the procedure and others hardly ever. Personally I do not routinely offer this procedure unless there are compelling reasons to do so. Normally the big toe in rheumatoid arthritis is significantly deviated and merely replacing the ends of the bones does not correct the deformity. If the surgery is carried out and for some reason the surgery fails, it is difficult to salvage the situation. This is because too much bone has been removed in the first place to make fusion possible. It is for this reason that I recommend fusion rather than joint replacement of the big toe.

The Mid-foot

In the middle part of the foot rheumatoid arthritis can lead to collapse of the arch. Supportive shoes and inner soles can be quite effective at "propping up" the arch but when the deformity is rigid such devices can be very uncomfortable and therefore if they are to be used they have to be made of soft cushioned material. If such devices fail to relieve pain then the mainstay of surgical intervention involves fusing the affected joints. It is important to fuse the joints which are responsible for the pain and sometimes it is difficult to establish exactly which joints are the source of pain. If a symptomatic joint is left un-fused then no benefit will be gained by surgery. This might mean a patient undergoes surgery, spends 3 months in a plaster only to be left with the same pain that was present prior to surgery. To aid in establishing which joints are painful so-called diagnostic injections can be very helpful. This involves injecting local anaesthetic into the affected joints and finding out which joints are responsible for the pain. Only when all the painful joints are successfully fused will pain be relieved. Unfortunately not all the joints of the foot can be fused in one go and if all joints were to be fused the foot would be unacceptably stiff. It is therefore imperative that careful pre-operative assessment takes place followed by meticulous surgery. Having said this fusion of the mid-foot joints can be very effective at relieving pain. Because many of the mid-foot joints do not move a lot in the normal foot, fusion of these joints is tolerated well and as a general rule, does not lead to noticeable stiffness. The surgery itself involves removing what remains of the cartilage in the joints and compressing the bone surfaces with screws. There are some joints in the mid-foot which are difficult to hold with screws and in these cases special "memory" staples can be employed. These are staples made of a material which is flexible at low temperatures but which, on warming to body temperature, stiffen and squeeze the bones together.

The Hind-foot

There are three joints in the hind-foot which although separate all act together. This means that if one of these joints is affected the others will, to a certain extent, be stiff even if they are not affected by the disease process. Rheumatoid arthritis tends to affect these three joints late on in the progression of the disease but when it does occur it can be disabling and lead to severe deformities. The mainstay of surgery for these joints is fusion. Conventionally in the past fusion of all three joints (subtalar, talonavicular and calcaneocuboid) has been practised. This is the so-called triple arthrodesis and it remains a highly effective way of dealing with pain from these joints. Unfortunately it does lead to profound stiffness of the foot. It is only recently that progressive foot and ankle surgeons have advocated fusing only the affected joint(s). In particular isolated talonavicular and isolated subtalar joint fusions are very good alternatives to a triple fusion in appropriate cases. Although fusing the talonavicular joint leads to profound stiffness in the other two joints, the operation is shorter and normal joints are not being unnecessarily sacrificed. Remember if all three joints are operated upon, and one fails to fuse the operation will be a failure. If the joint which does not fuse did not need to be operated upon in the first place, much harm will have been done.

Although the period in plaster following hind-foot fusions is normally three months, the end results can be especially pleasing, not only in terms of pain relief but also correction of deformity. This type of surgery is very complex, so it is advisable to discuss the procedure in detail with your surgeon and to ask about their level of experience in performing this surgery.

The Ankle

Like all the other joints in the foot the ankle joint can be the source of great pain and misery to the rheumatoid patient. The ankle is less likely to deform than the hind-foot joints when affected by rheumatoid arthritis but when deformity occurs it can be quite spectacular. Innersoles have a limited role in the treatment of the rheumatoid ankle and realistically any mechanical device which is likely to help has to come above the ankle. Such devices rarely fit inside shoes and therefore usually take the form of a rather cumbersome brace. Having said this, there have been great advances in the design of these braces and the materials used in recent years.

Sometimes an inflamed ankle joint can be helped by key-hole surgery (arthroscopy). This involves washing out the joint and removing the inflamed lining of the joint. Unfortunately though, most ankles affected by rheumatoid arthritis are beyond help by this type of surgery and therefore fusion or joint replacement needs to be considered.

There is no doubt that a successful ankle fusion can lead to excellent pain relief but it does lead to marked stiffness and if other joints are involved the stiffness can be quite profound. Despite this, ankle fusion remains my favoured option in most cases of severe arthritis of the ankle. Ankle joint replacement is now becoming established as an alternative but there is no doubt that it is not as successful or long lasting as hip or knee replacements. The early experience of ankle replacements was very disappointing indeed but there have been great improvements in the design and there are now several makes commercially available. Some surgeons claim excellent results and there is no doubt that when a successful ankle replacement maintains good motion patients are very happy indeed with the operation. The problem with ankle replacement, as with big toe joint replacement, is that if it fails and needs to be removed salvage can be very difficult indeed. I have no doubt however that ankle joint replacement will become a viable alternative to fusion in the near future. Personally I reserve ankle replacements for the elderly and the relatively immobile rheumatoid patients.

Summary

Surgery has a lot to offer the rheumatoid patient with foot and ankle problems. In the last 15 years there has been an explosion of interest in foot and ankle surgery and there are now many orthopaedic surgeons in the UK who specialise in foot and ankle surgery. The newer techniques are therefore more widespread and practised by a greater number of foot and ankle surgeons, providing more availability with a wider range of treatment options for the rheumatoid patient.

References available on request

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