Positive Health Online

Nature abhors friction. Wherever in our bodies, parts move over one another, evolution has provided cushions in the form of fluid-containing tissue spaces called bursae. There are two kinds: bursae mucosae and bursae synovia. The former are found between bone and skin or subcutaneous tissues, like the malleolar or ankle bursae; the latter, which are more common, occur around joints and places where tendons pass over bones. For added comfort and efficiency, tendons are also equipped with slings for support and synovial sheaths for gliding. The distinction between synovial bursae and synovial sheaths is not always a clear one. Indeed, some structures labelled bursae by some anatomists, are labelled synovial sheaths by others.

A number of the muscles acting on the foot have to negotiate sharp right angled bends at the ankle joint. Muscles don't venture in places with such harsh mechanical conditions. Tendons, fitted with their protective covering and cushioning, are better suited to the job. This is why the muscles in the leg which act on the foot have long tendons. Not surprisingly, the foot is packed with bursae. On the dorsum or back of the foot alone one can count half a dozen or more of these pads. There are even some little ones occupying the clefts between the toes which have a mouthful of a name. So next time you have your feet examined, ask – and impress – your chiropodist by requesting them to check your bursae intermetatarsophalangeae.

The workings of the complex organism that is our body cannot avoid a certain amount of pressure and friction. The response to this normal mechanical stress is the bursa that prevents any damage and undue wear. Because nature knows, from experience, where to anticipate the places where rubbing of parts will happen, the normal bursae in our bodies are formed long before there is occasion for any friction to take place. They are inherited, developed before birth. But, apart from their universal and constant occurrence, some bursae may appear, de novo, in other places, according to individual conditions of use – or misuse. In response to unaccustomed mechanical duress, the body is perfectly able to manufacture some bits of anatomical upholstery. In the world of bursae we must therefore distinguish between the normal, the adventitious and the pathological.

Definitely pathological is the bursa which develops at the head of the metatarsal bone of the big toe when it is bent into a hallux valgus deformation, i.e. deflected towards the other toes. When this bursa becomes inflamed, it develops into what is known as a bunion (oignon in French!). The tissues around the joint swell and harden, forming a painful bump, and the joint progressively loses its mobility. The hallux valgus condition is said by some authors 'to run in the family'. It is also said that 'shoes are usually blamed, but their effect may not be as great as supposed'. On this subject Thomas Ellis,[1] an authority on the foot, wrote that: "This very common deformity is very frequently supposed to have a hereditary origin, and the subjects of it flatter themselves that it is not due to boots at all. The tendency may be hereditary, but the exciting cause, such as distortion or pressure, must always exist." To behave like Cinderella's competitors by forcing our feet into shoes not made for them can lead to bunioned toes. If hallux valgus runs in the family it could be because habits of misuse also 'run' in the family – they are easily mimicked and unconsciously adopted at an early age.

It is true that shoes are not the sole factor in the causation of hallux valgus; you could walk barefoot all your life and still develop this common deformity of the big toe (see my previous column). But it is also obvious that shoes, especially the pointed ones, i.e. most of them, play an important factor in disfiguring the big toe. The little toe too suffers from its own deformation known as quintus varus where it is bent towards its fellow toes, and it is not uncommon for it also to develop a small bunion. When the big and little toes look cross-eyed it is difficult not to put a foot wrong.

When the condition is not too advanced, the big toe can return to a straight position. Success depends on the removal of excess tone in the muscles that run in the back of the whole body and some local corrective treatment with repeated powerful pulling of the toe towards its normal axis. It is essential, though, to wear shoes that respect the natural shape of the foot lest any progress be lost. It's not good enough that the shoes fit the bunion, they have also to be wide enough to let the big toe resume its true line. But the big toe can seriously deviate from its normal position and ride over or, more often, under the second toe. In the latter condition, the second toe will be crooked into a claw shape. Besides the valgus habit of the hallux and the varus habit of the quintus, toes can suffer from various other deformations such as claw, mallet or hammer toes. Toes don't go into a hammer shape because of the presence of nails in the vicinity but because of the shortening of the deep muscles in the back of the lower leg. The second toe is often the most affected.

As a secondary effect, the transversal arch of the foot is depressed and the ball of the foot bulges downwards. To protect itself against undue rubbing and pressure, the skin becomes pachydermatous with callosities and corns.

If you don't want painful and inefficient feet, don't be callous with them, give its 31 joints plenty of space by choosing sensible shoes and, whenever it's possible, do discalceate[2] and walk barefoot.

Notes and References

1. Ellis, TS. The Human Foot, its Form and Structure, Function and Clothing. London. Churchill. 1989.
2. Discalceate: v.t & i. – Take off the shoes (of). adj. – Barefoot; wearing sandals as the only footwear. n. – A discalceate friar or nun.