RUPTURE OF THE CALCANEAL TENDON

Surprising as it may seem, a ruptured calcaneal tendon (tendo Achillis) is often overlooked, the symptoms being wrongly ascribed to a strain or to a ruptured plantaris tendon.

Pathology. The rupture is nearly always complete. It occurs about 5 cm above the insertion of the tendon. If it is left untreated the tendon unites spontaneously, but with lengthening and loss of function.

Clinical features. While running or jumping, the patient feels a sudden agonising pain at the back of the ankle. He may believe that something has struck him. He is able to walk, but only with a bad limp. On examination of the back of the heel there is tenderness at the site of rupture. There is general thickening from effusion of blood and from oedema of the paratenon, but a gap can usually be felt in the course of the tendon. The power of plantarflexion at the ankle is greatly weakened, though some power remains through the action of the tibialis posterior, the peronei, and the toe flexors. A useful test, to be carried out with the patient prone, is to squeeze the bulk of the calf muscles from side to side. Normally this causes a slight plantarflexion movement of the foot, but not if the tendon is ruptured.

Diagnosis. The retention of some power of plantarflexion may deflect the unwary from the correct diagnosis. The crucial test is to ask the patient to lift the heel from the ground while standing only upon the affected leg (Fig. 19.5). This is impossible if the tendon is ruptured. In cases of doubt the gap in the tendon may be well demonstrated by ultrasound or MRI scanning (Fig. 19.6).

Fig. 19.6 A Ultrasound of normal Achilles tendon. Patient’s foot on right. Normal appearance of tendon seen above the word ‘Tendon’. B Compare with this ultrasound of a ruptured tendon.

Treatment. Non-operative treatment may be used in selected cases, usually older and more sedentary patients who make less demands on their ankle function. The method is only applicable where passive ankle flexion can bring the torn ends of the tendon into apposition. The ankle is then immobilised in a below-knee plaster for 5 weeks, with the foot in slight equinus to relax the tendon and thus help to prevent lengthening.

In the majority of younger patients, particularly those who wish to continue athletic pursuits after healing, operative treatment is preferable. It entails repair of the tendon, using non-absorbable sutures of synthetic material, tension on the suture line being relaxed by immobilising the limb with right-angled knee flexion and moderate ankle plantarflexion for 2 weeks. For the next four weeks a below-knee plaster with the ankle at 90° is worn. Certain protocols allow earlier mobilisation of the ankle under close supervision of a physiotherapist.

Whether treatment is by plaster alone or by operation, it must be completed after removal of the plaster by increasingly vigorous exercises for the calf muscles, practised under the supervision of a physiotherapist until full strength is restored.

ACUTE OSTEOMYELITIS (General description of acute osteomyelitis, p. 85)

The tibia is one of the commonest sites of haematogenous osteomyelitis. Because of its liability to open (compound) fracture it is also the commonest site of osteomyelitis from direct contamination. The fibula is less often affected.

The pathological and clinical features and treatment conform to the general description on page 89.

CHRONIC OSTEOMYELITIS (General description of chronic osteomyelitis, p. 90)

Chronic osteomyelitis in the lower leg, as elsewhere, is nearly always a sequel of acute osteomyelitis. It may follow either the haematogenous type of infection or an infected open fracture.

Brodie’s abscess. This rather uncommon lesion was described on page 92. It is a special form of chronic osteomyelitis which arises insidiously, without a recognised acute infection preceding it. The tibia is the commonest site (see Fig. 7.7, p. 93).

SYPHILITIC INFECTION OF THE TIBIA (General description of syphilitic osteitis, p. 95)

Although skeletal syphilis is now rare in Western countries, it still occurs in other parts of the world, and when it does occur the tibia is often the bone affected. The infection may take the form of a localised gumma or of diffuse osteoperiostitis (see Fig. 7.11A&B, p. 96). There is a gradually enlarging swelling, with moderate pain. It is important to bear the possibility of syphilis in mind, because the swelling is easily mistaken for a tumour.

TUMOURS OF BONE

INTERMITTENT CLAUDICATION

Intermittent claudication is a symptom of arterial insufficiency in the lower limb. In its typical form it is characterised by cramp-like pain in the calf, induced by walking and relieved by rest.

Cause. The usual underlying cause is arteriosclerosis with consequent partial or total obstruction of the main limb vessel. Thrombo-angiitis obliterans and arterial embolism are less common causes. Tobacco smoking is a major contributory factor.

Pathology. The basic disturbance is ischaemia of muscle, in consequence of which metabolites cannot be removed speedily enough when the muscle is exercised. The accumulation of metabolites is believed to be responsible for the pain, which subsides within a few minutes when the muscle is rested. The muscles usually affected are those of the calf, but in some instances other muscle groups are involved, according to the site of the arterial obstruction. The vascular lesion is usually a complete occlusion of the femoral or the popliteal artery. In claudication affecting the buttock the aortic bifurcation or the iliac artery may be occluded.

Clinical features. Intermittent claudication is much more common in men than in women. In the usual arteriosclerotic type the patient is past middle life, but in cases due to thrombo-angiitis obliterans or embolism the symptoms may develop in early adult life. The patient is usually a regular smoker.

With gradual arterial occlusion the onset is insidious and the symptoms are slowly progressive; but in cases precipitated by thrombosis or embolism the onset may be sudden. In a typical case the patient complains that after walking a certain distance – perhaps a hundred metres or so – he is forced to stop by severe cramp-like pain in the calf, or occasionally in another muscle group, such as the buttock. After a few minutes’ rest the pain disappears and he is able to walk on again for a similar distance.

On examination there is objective evidence of impaired arterial circulation in the lower limb (p. 421). The posterior tibial, dorsalis pedis, and popliteal pulses are absent. There may be ischaemic changes in the skin of the foot. Evidence of widespread arterial or cardiac disease is nearly always found on general examination.

For further details on the investigation, diagnosis and treatment of this condition readers should refer to a textbook of vascular surgery.

PYOGENIC ARTHRITIS OF THE ANKLE (General description of pyogenic arthritis, p. 96)

Pyogenic arthritis of the ankle is uncommon. The organisms reach the joint through the blood stream or through a penetrating wound; local spread from a focus of osteomyelitis of the tibia or fibula is rare because the bony metaphyses are entirely extra-capsular (see Fig. 7.2, p. 87).

TUBERCULOUS ARTHRITIS OF THE ANKLE (General description of tuberculous arthritis, p. 98)

Tuberculosis is much less common in the ankle than it is in the hip and knee. In Britain it is now seen very seldom. When it is seen, it is often in an immigrant from a developing country.

The clinical features correspond to those of tuberculous arthritis of other superficial joints, with pain, swelling, increased warmth of the overlying skin, restriction of movement, and limp.

Treatment. Early conservative treatment (p. 102) may restore a mobile ankle, but if in a resistant case articular cartilage is badly eroded or destroyed arthrodesis may have to be undertaken.

RHEUMATOID ARTHRITIS OF THE ANKLE (General description of rheumatoid arthritis, p. 134)

One or both ankles are often affected by rheumatoid arthritis in common with other joints in the lower limb, particularly the foot. There may be marked destruction of the articular cartilage and subchondral bone with pain, stiffness, and deformity (Fig. 19.7).

Fig. 19.7 Radiographs of the ankle with advanced rheumatoid arthritis showing loss of joint space and erosion of the articular surfaces of the tibia and talus.

Treatment. Medical treatment is along the lines suggested for the disease as a whole (p. 137). Local treatment: In the active phase rest in a plaster is sometimes required, but in most cases the patient should be encouraged to remain active as far as possible, with such help as may be gained from local support by a moulded polypropylene splint. Operation is advised mainly when destruction of articular cartilage has led to intractable pain with marked impairment of capacity for walking. Arthrodesis and replacement arthroplasty are the methods available. Arthrodesis is usually the operation of choice because it gives permanent relief of pain with good function. If the subtalar and midtarsal joints are also severely affected they should be included in the fusion. Replacement arthroplasty of the ankle is appropriate in some patients (Fig. 19.8). The operation is technically demanding because of the limited surgical access to the joint, while the long-term results are much less satisfactory than with the hip or knee because poor bone support may lead to early implant loosening.

Fig. 19.8 A and B Radiographs of a Scandinavian total ankle replacement arthroplasty inserted for the treatment of advanced rheumatoid arthritis. Metal prostheses have been used to resurface the dome of the talus and the distal tibia and both articulate with a mobile polyethylene meniscal prosthesis placed between them (position shown by wire marker).

OSTEOARTHRITIS OF THE ANKLE (General description of osteoarthritis, p. 140)

Degenerative destruction of the articular cartilage is less common in the ankle than in the knee or hip. There is nearly always a known predisposing factor which causes the joint to wear out prematurely. The commonest is irregularity or mal-alignment of the joint surfaces after a fracture. Sometimes articular disease such as previous rheumatoid arthritis or osteochondromatosis is the primary factor.

Clinical features. The symptoms are pain which slowly increases over months and years, and limp. On examination the joint is a little thickened from hypertrophy of bone (osteophyte formation) at the joint margins. Movements are restricted slightly or severely according to the degree of arthritis.

Radiographs show the typical features of osteoarthritis – narrowing of the cartilage space, a tendency to sclerosis of the bone adjacent to the joint, and osteophyte formation at the joint margins (Fig. 19.9).

Fig. 19.9 Osteoarthritis of the ankle complicating fracture-subluxation 10 years before. Note the marked narrowing of the cartilage space and the prominent osteophytes.

Treatment. In mild cases treatment is often unnecessary, because the patient may be willing to accept the disability when the nature of the trouble has been explained. When treatment is called for, conservative measures should be tried first if the disability is only moderate. Physiotherapy by short-wave diathermy, and active exercises are usually advised. Sometimes local splintage by a moulded polypropylene support will provide relief while allowing the patient to continue to walk. Such treatment, however, is only palliative, and if the disability increases to the extent of becoming a serious handicap operation should be undertaken.

Surgical treatment should usually be by arthrodesis, which provides a painless stable joint for many years. A number of different methods are available to produce reliable bony fusion and with the introduction of arthroscopic techniques to remove the degenerate cartilage, combined with rigid internal fixation across the opposed bone surfaces, the post-operative rehabilitation is rapid. Unfortunately, after 10–15 years more than 50% of these patients develop further disability from hindfoot pain because of the accelerated onset of arthritis in the adjacent sub-talar and talo-navicular joints. In an attempt to overcome this problem in younger patients, replacement arthroplasty with resurfacing prostheses has been explored as a possible alternative (see Fig. 19.8). As with arthroplasty for rheumatoid arthritis, the long-term results are still uncertain because of bone resorption and implant loosening and it is not yet widely recommended.

NEUROPATHIC ARTHRITIS OF THE ANKLE (General description of neuropathic arthritis, p. 147)

Neuropathic arthritis is uncommon but nevertheless well recognised in the ankle. The underlying neurological disease is diabetic neuropathy, syringomyelia, cauda equina lesion, tabes dorsalis, or, where it is prevalent, leprosy.

Treatment. In many cases protection by a firm surgical boot, reinforced if necessary by a below-knee brace, is all that is required. Occasionally arthrodesis of the ankle may have to be considered. Appropriate treatment must be given for the underlying neurological disorder.

RECURRENT SUBLUXATION OF THE ANKLE

When the lateral ligament of the ankle is torn and fails to heal there may be persistent instability with recurrent attacks of giving way in which the talus tilts medially in the ankle mortise. Anterior displacement relative to the tibial articular surface may also occur. The causative injury is always a severe inversion force.

Clinical features. The patient complains that the ankle ‘goes over’ at frequent intervals, often causing him to fall. Each incident is accompanied by pain at the lateral side of the ankle. There is always a history of previous severe injury, followed by much swelling and extensive bruising at the lateral side of the joint.

On examination there is often some oedema about the ankle. There is tenderness over the site of the lateral ligament. The normal ankle movements – dorsiflexion and plantarflexion – are unchanged, but abnormal mobility is present as shown by the fact that the heel can be inverted passively beyond the normal range permitted at the subtalar joint. Moreover, when the heel is fully inverted a dimple or depression of the skin may be visible in front of the lateral malleolus, where the soft tissues have been ‘sucked’ into the gap created between tibia and talus.

Radiographic features. Routine radiographs do not show any abnormality. Antero-posterior films must be taken while the heel is held fully inverted. If the lateral ligament is torn or lax the talus will then be shown tilted away from the tibio-fibular mortise at the lateral side through 20 or 30° or more (Fig. 19.10). Anterior displacement of the talus relative to the tibial articular surface may sometimes also be demonstrated in lateral radiographs taken while the foot is pushed forwards.

Fig. 19.10 Tilting of the talus in the ankle mortise under adduction stress; an indication of torn lateral ligament.

Diagnosis. Chronic strain of the lateral ligament may cause similar symptoms, but in that condition radiographs will not show the talus tilted significantly on forced inversion. (It should be noted that the talus may tilt up to 10° or even 15° in a normal ankle. Tilting beyond that amount is demonstrated only when the ligament is torn.)

Treatment. If the disability is slight it may be sufficient to strengthen the evertor muscles (mainly the peronei) by exercises, to enable them to control the ankle more efficiently. Stability may also be enhanced by broadening and ‘floating out’ the heel of the shoe. If the disability is severe operation is required. A new lateral ligament may be constructed either from the peroneus brevis tendon or from the peroneus tertius. Trials are also proceeding with the use of artificial ligaments, either as substitutes or as a means of promoting the growth of new ligamentous tissue.

CONGENITAL CLUB FOOT (Talipes equino-varus)

The rather vague term ‘club foot’ has come to be synonymous in the minds of most surgeons with the commonest and most important congenital deformity of the foot—talipes equino-varus (Fig. 19.11). The less common, and usually less serious, form of club foot, talipes calcaneo-valgus, will be considered later under that title.

Fig. 19.11 Bilateral club foot (talipes equino-varus) in an infant boy. Note the poor development of the calf muscles.

Cause. This is still under debate. In most cases a defect of fetal development is responsible, with imbalance between the invertor-plantarflexor muscles and the evertor-dorsiflexor muscles. A neuromuscular defect is possibly relevant. Minor degrees of the deformity may possibly be explained by prolonged mal-position of the foetal foot in the uterus, but this cannot be accepted as the usual cause.

Pathology. The crucial component of the deformity is subluxation of the talo-navicular joint, so that the navicular bone lies partly on the medial aspect of the head of the talus instead of on its distal aspect (Fig. 19.12). The soft tissues at the medial side of the foot are under-developed and shorter than normal. The foot is adducted and inverted at the subtalar, midtarsal, and anterior tarsal joints, and is held in equinus (plantarflexion) at the ankle. In most cases under-development of the calf and peroneal muscles is a striking feature. Thus if only one foot is affected there is a marked discrepancy in the girth of the calf between the two sides.

Fig. 19.12 A Normal alignment of the forefoot upon the long axis of the talus. B Subluxation of the navicular bone medially on the head of the talus – the crucial component in the pathology of talipes equino-varus. Interrupted line shows forward projection of the long axis of the talus passing lateral to the first metatarsal – a useful radiological sign. In the normal state the line passes through or medial to the first metatarsal A.

In the absence of early effective treatment the developing tarsal bones assume an abnormal shape as growth occurs, perpetuating the deformity.

Clinical features. The deformity is much commoner in boys than in girls. (Contrast developmental dysplasia (congenital dislocation) of the hip, which is much commoner in girls.) One or both feet may be affected. When the infant is born it is noticed that the foot is turned inwards so that the sole is directed medially (Fig. 19.11). The deformity, to be more precise, consists of three elements:

The foot cannot be pushed passively through the normal range of eversion and dorsiflexion. There may be obvious under-development of the muscles of the lower leg, especially noticeable when only one foot is affected.

Diagnosis. New-born infants should be examined routinely for evidence of club foot. It is not sufficient, for purposes of diagnosis, that the foot be found to rest in the position described, for often the feet of normal infants tend to lie naturally in a somewhat inverted position. The criterion for the diagnosis of club foot is that the deformity cannot readily be corrected and over-corrected to bring the foot into eversion and dorsiflexion. It should be remembered that in normal infants under 1 year old it is possible to evert and dorsiflex the foot far enough to bring the little toe into contact with the shin.

Radiographic features. In the antero-posterior radiograph of a normal foot a line projecting the long axis of the talus forwards passes medial to the first metatarsal bone or coincides with it (Fig. 19.12A). In uncorrected or incompletely corrected club foot the line passes lateral to the metatarsal (Fig. 19.12B).

Prognosis. The prognosis depends largely upon the age at which primary treatment is begun, and upon the efficiency with which it is carried out. The longer the delay before treatment, the smaller is the prospect of complete cure. Yet even with prompt treatment the outcome is uncertain. In a proportion of cases, despite the greatest care from the time of birth, there is a tendency to relapse when treatment is discontinued. These are usually the cases that show marked hypoplasia of the muscles of the lower leg, especially of the peroneal group. Even in the most severe cases, however, it should always be possible to ensure a plantigrade foot, if not a normal foot, by operative means.

Treatment in a fresh case. Although it is seemingly a simple deformity, talipes equino-varus presents difficult problems in treatment. The most widely accepted practice is to rely upon conservative treatment by correction and splintage during the first year of life (often using the so-called Ponseti technique¹) and often well beyond that; if casting and splintage fail to correct the position then operative correction is carried out.

Primary conservative treatment. Ideally treatment should be begun immediately after birth – certainly not more than 1 week later. The principles of treatment are:

Correction of deformity. The deformity is corrected by firm manual pressure without anaesthesia (Fig. 19.13). The Ponseti technique involves first correcting the cavus deformity, then the adduction and heel varus, and finally the equinus deformity. Depending on the severity of the deformity, it may be possible to correct it fully by two or three manipulations, or as many as five or six manipulations at weekly intervals may be required.

Fig. 19.13 Correcting a club-foot deformity by manual pressure without anaesthesia. Note that pressure is applied under the midfoot, not under the forefoot.

Maintenance of correction. Three methods are available for holding the foot in the corrected position between manipulations:

Retention in a plaster is much to be preferred, because it holds the foot in the over-corrected position more efficiently and for a longer period than do metal splints or strapping – even though the technique of applying a plaster correctly is not easy to learn. The plaster must extend to the upper thigh, with the knee flexed 90° (Fig. 19.14); otherwise the infant is able to draw the foot up inside the plaster, with consequent loss of correction. The plaster must be changed every week at first, but the interval may be extended to two and then three weeks as the child grows larger.

Fig. 19.14 Plaster for maintaining correction in congenital club foot. It is essential to include the thigh, with the knee flexed to a right angle.

Operative treatment. Opinions vary on the correct duration of conservative treatment and on the timing of corrective operations in infants. If treatment by manipulation and retention fails, operation should usually be undertaken before the age of 9 months: some would say much earlier. If at the end of three or four months the feet are not normal clinically and radiologically, operation should be advised. The idea behind early operation is to set the tarsal bones in normal relationship to one another and to remove deforming forces, thus allowing the bones to develop in their normal shape from an early age. All taut ligaments at the medial side of the ankle and foot are divided and any tendon that is too tight to allow full correction is lengthened – including the calcaneal tendon. Finally the tarsal bones, thus released, are restored to their normal relationships, particular attention being paid to the talus and the navicular bone. After operation a plaster is worn for 2 or 3 months.

Treatment in neglected or relapsed cases. Repeated manipulation and retention in plaster can produce worthwhile improvement in children of up to two years of age. If significant deformity is still present after the age of two, operative treatment is required. It should be appreciated that in these late cases no method of treatment – whether conservative or operative – is capable of restoring the foot to normal. The most that can be done is to restore a plantigrade foot.¹

Types of operation. In children aged 2 to 12 years there is the option to employ any of seven operations, depending upon the circumstances of each case:

In children over the age of 12 resort must be had to operation upon the bones: a wedge of bone of appropriate size (with base dorso-laterally) is removed from the tarsus so that when the resulting gap is closed the foot is plantigrade. This operation is not recommended for children under 12 because the active bone growth of the foot is likely to be impaired.

CONGENITAL TALIPES CALCANEO-VALGUS

This is the opposite deformity to talipes equino-varus. The foot is everted and dorsiflexed. It is usually a less serious deformity than talipes equino-varus and with few exceptions, in which there is displacement at the talo-navicular joint (see congenital vertical talus, below), it responds readily to treatment.

Cause. The cause is unknown. In some cases it may simply be a postural deformity, from folding of the foot against the shin for a long time in intra-uterine life.

Clinical features. One foot or both feet may be affected. The foot rests in a position of eversion and dorsiflexion, so that its dorsum lies almost in contact with the shin (Fig. 19.15). Tightness of the dorso-lateral soft tissues prevents the foot from being brought down easily into inversion and equinus, though with steady pressure a fair degree of correction can usually be obtained.

Fig. 19.15 Congenital talipes calcaneo-valgus. The typical deformity.

Treatment. In most cases the deformity will respond to repeated manual stretching by the parents, who should be carefully instructed how to coax the foot into the over-corrected position of inversion and equinus by steady pressure upon the dorsum of the foot. The manipulations should be begun immediately after birth and should be carried out several times a day.

If calcaneo-valgus deformity still persists when the child is a month old more intensive supervision is required. The surgeon should gently over-correct the deformity as far as possible by manipulation without anaesthesia, thereafter applying a plaster with the foot in the over-corrected position. The plaster is changed weekly until a full range of inversion and equinus is gained. At that stage the plaster may be discarded without fear of relapse.

ACCESSORY BONES IN THE FOOT

Many accessory bones have been described in the foot, but most are of little or no practical importance. The commonest is the os trigonum, which lies immediately behind the talus, on the upper surface of the tuberosity of the calcaneus (Fig. 19.16). It does not cause symptoms. It may be confused with a fracture of the talus.

Fig. 19.16 Os trigonum.

The only tarsal accessory bone that is frequently responsible for symptoms is the os tibiale externum¹ (accessory navicular bone) (Fig. 19.17). This lies medial to the navicular bone, and forms a well-marked prominence at the inner border of the foot which may become painful and tender from the pressure of the shoe. If the symptoms justify operation the accessory bone should be removed.

Fig. 19.17 Os tibiale externum.

PES CAVUS

In pes cavus or ‘hollow foot’ the longitudinal arch of the foot is accentuated.

Cause. In many cases the deformity has a congenital basis. It is sometimes familial. In other cases there is an underlying neurological disorder causing muscle imbalance. For instance, it is often associated with a minor degree of spinal dysraphism (p. 171), or it may follow poliomyelitis.

Pathology. The metatarsal heads are lowered in relation to the hind part of the foot, with consequent exaggeration of the longitudinal arch. The soft tissues in the sole are abnormally short, and eventually the bones themselves alter shape, perpetuating the deformity. There is always associated clawing of the toes, which are hyperextended at the metatarso-phalangeal joints and flexed at the proximal and distal interphalangeal joints (Fig. 19.18). This clawing seems to result from defective action of the intrinsic muscles – lumbricals and interossei. The effect is that the toes are almost functionless, and unable to take their normal share in weight-bearing. Consequently excessive weight falls upon the metatarsal heads on walking or standing, and hard callosities form in the underlying skin. The mal-alignment of the tarsal joints predisposes to the later development of osteoarthritis.

Fig. 19.18 Pes cavus. Typical deformity with high arch, clawed toes, and prominence of the metatarsal heads in the sole. In such a case the spine should always be examined for evidence of dysraphism.

Clinical features. The deformity often becomes evident in childhood. It may affect one foot or both feet. In some cases the symptoms are negligible. When symptoms do arise they may take three forms:

On examination the deformity is characteristic and easily recognised (Fig. 19.18). The longitudinal arch is high; the forefoot is thick and splayed; the toes are clawed; the metatarsal heads are prominent in the sole. Callosities beneath the metatarsal heads indicate that they take excessive weight. The toes cannot be straightened at will by the patient, nor can they be pressed firmly upon the ground to take a share in weight-bearing. There may also be tender callosities where the tops of the toes have rubbed against the shoes.

The base of the spine should be examined for a congenital anomaly such as spina bifida, which may be suggested by the presence of a dimple, a tuft of hair, or an area of pigmentation. If suspicion of spinal dysraphism exists radiographs of the spine should be obtained.

Treatment. In many cases treatment is not required. Mild symptoms can often be relieved by regular chiropody and by the provision of a resilient pad beneath the metatarsal heads to distribute the weight more widely. It is often helpful to prescribe surgical shoes, made to fit the altered shape of the feet.

If the symptoms are severe operation may be required. The nature of the operation should depend upon the cause of the main symptoms.

Operations on the toes. When local pressure upon the toes or beneath the metatarsal heads is the main complaint, adequate relief can often be afforded simply by straightening the clawed toes. This may be done by arthrodesing all the interphalangeal joints or, if the toes are still mobile, by transplanting the long flexor tendon into the extensor expansion to supplement the action of the intrinsic muscles.

Operations on the soft tissues of the sole. In appropriate cases arthrodesis of the toes may be supplemented by the Steindler muscle-slide operation, in which the taut ligamentous tissues in the sole of the foot are detached from the calcaneus and allowed to slide forwards as the height of the arch is reduced by strong manual force. After operation the correction is maintained by immobilising the foot in plaster for 2 months.

Operations on the tarsal joints. When osteoarthritis of the tarsal joints is the main cause of the symptoms arthrodesis of the affected joints – usually the subtalar, calcaneo-cuboid, and talo-navicular joints (the so-called triple arthrodesis) – is required. At the same time the deformity is corrected by excising a wedge of bone, base upwards, from the metatarsus. When necessary, this operation may be combined with operations to straighten the toes.

PES PLANUS (Flat foot; valgus foot)

In this common condition the longitudinal arch of the foot is reduced so that, on standing, its medial border is close to, or in contact with, the ground (Fig. 19.19). It is usually associated with some degree of twisting outwards of the foot on its longitudinal axis (eversion or valgus deformity).

Fig. 19.19 Pes planus. Marked flattening of the longitudinal arch, with valgus deformity seen well from behind (inset).

Cause. In many cases it probably has a congenital basis, but it may be caused by selective muscle weakness or paralysis.

Pathology. All infants have flat feet for a year or two after they begin to stand. When the deformity persists into adult life it becomes a permanent structural defect, the tarsal bones being so shaped that when articulated they tend to form a straight line rather than an arch.

Clinical features. In children, flat feet are usually symptomless, but the parents commonly complain that the uppers of the shoes persistently bulge inwards and that the heels wear down quickly at the inner sides.

In adults, too, flat feet are often free from symptoms, but they are more liable than are normal feet to suffer foot strain (p. 444), and when pain is complained of it is usually from that cause.

In later life pain may also arise from osteoarthritis of the tarsal joints consequent upon their mal-alignment.

Treatment. In children under 3 years old treatment is not required. In children over 3 the accepted method of treatment is to tilt the shoe slightly to the lateral side by inserting a wedge, base medially, between the layers of the heel (not the sole) (Fig. 19.20). This may help to overcome the valgus twist and to reduce the bulging-over of the uppers at the medial side, but it must be accepted that in most cases it is little more than a placebo. In older children it is better to insert a valgus insole (arch support) into the shoe, and this may be supplemented by a course of supervised exercises to strengthen the intrinsic muscles of the foot.

Fig. 19.20 Shoes drawn from behind, to illustrate medial heel wedges.

In cases of severe valgus deformity – which is usually the consequence of selective muscle imbalance, as after poliomyelitis – operation to restore the correct relationship between talus and calcaneus, and to fuse the two bones together (talo-calcaneal arthrodesis), may be considered. In children this operation may be done by placing bone grafts extra-articularly in the sinus tarsi, from the lateral side.

In adults treatment is not needed unless symptoms are present, when the advisability of fitting an arch support should be considered. Supports are seldom of benefit when the foot is completely flat, but they often afford relief when the longitudinal arch is diminished but not lost.

If the symptoms in a case of long-established flat foot are ascribed to superimposed osteoarthritis of the tarsal joints, treatment should be directed against the arthritis (see below).

FOOT STRAIN

The term ‘foot strain’ implies a subacute or chronic strain of the tarsal ligaments, not an acute injury from sudden violence.

It may be caused in a normal foot by excessive standing or walking by a person unaccustomed to it: but it occurs mostly in those with a long-established foot deformity such as pes planus (flat foot) or pes cavus, when the ligaments of the foot may be inadequately protected by muscles.

The main symptoms are prolonged aching in the feet, worse on standing or walking, often with aching also in the calves.

It is important to eliminate other causes of foot problems such as ischaemia, neurological deficit and, in boys, particularly muscular dystrophy.

Treatment should be by reducing the time spent in standing and walking, by the fitting of an arch support if indicated, by supervised foot and toe exercises, and sometimes by electrical stimulation to strengthen the muscles of the leg and foot.

OSTEOARTHRITIS OF THE TARSAL JOINTS

Osteoarthritis may affect any of the tarsal joints, but in practice it is seen most often in the subtalar and midtarsal joints. It seldom arises primarily: there is nearly always a predisposing cause such as previous fracture or disease involving the joint surfaces (especially fractures of the calcaneus), or mal-alignment of the tarsal bones (as in severe flat foot or severe pes cavus).

Clinical features. The main symptom is pain, which gradually increases over months or years and finally leads to a limp and impaired capacity for walking. Pain is localised fairly accurately to the particular joint or joints affected. A history will usually be obtained of previous injury, disease, or deformity of the foot. On examination movement of the affected joint is impaired, and painful if forced.

Radiographs confirm the diagnosis and may give an indication of the primary underlying cause.

Treatment. In mild cases treatment is not required, especially if the patient’s activities can be curtailed. When the disability is troublesome more active measures are needed. Conservative treatment is only palliative, but it is usually worth a trial. It should take the form of short-wave diathermy, muscle exercises, and support from an elastic bandage or moulded polypropylene heel seat. A trial may also be made of local injection of hydrocortisone into the affected joint; but repeated injections are not advised.

If conservative treatment fails to give adequate relief operation must be considered. The only effective method is by arthrodesis of the affected joint or joints.

OTHER FORMS OF ARTHRITIS OF THE TARSAL JOINTS

Like all true synovial joints, the tarsal joints are liable to any of the recognised forms of arthritis, including pyogenic arthritis, rheumatoid arthritis, tuberculous arthritis, gouty arthritis, and neuropathic arthritis. Of these, the only one that is at all common is rheumatoid arthritis, which affects particularly thesubtalar joint.

OSTEOCHONDRITIS OF THE NAVICULAR BONE (Köhler’s disease¹)

The general subject of osteochondritis was discussed in Chapter 8 (p. 130). The growing navicular bone is one of its best-recognised sites. The developing nucleus of the bone is temporarily softened and usually becomes compressed by the mechanical forces entailed in walking. A disturbance of blood supply is possibly a causative factor, but the pathogenesis is not fully understood.

Pathology. The pathology is believed to be like that of osteochondritis of other growing bony nuclei (see Table 8.2, p. 131). The bone, presumably necrotic from ischaemia, loses its normal trabecular structure and may become fragmented as it is gradually absorbed and replaced by new living bone. After about two years the normal bone structure is restored and the bone may regain almost its normal size and shape. If slight deformation of the bone does remain, the growing foot seems to adapt itself to the altered shape and little or nodisability persists.

Clinical features. Köhler’s disease is confined to children aged about 3 to 5 years. The child complains of pain in the midtarsal part of the foot and is noticed to limp. On examination there may be slight swelling in the midtarsal region, with tenderness on firm palpation over the navicular bone and sometimes a slight increase in warmth. There may be some restriction of midtarsal movements with pain on forcing, but these signs are slight and sometimes absent.

Radiographic features. Radiographs are diagnostic. The ossifying nucleus of the navicular bone appears squashed antero-posteriorly (Fig. 19.21A); it is denser than normal, and may have a fragmented appearance. Serial radiographs during the 2-year span of the disease show the gradual evolution of the bone changes. After a stage of maximal density and deformation a few months after the onset there is gradual improvement until normal bone texture is restored (Fig. 19.21B).

Fig. 19.21 Köhler’s osteochondritis of the navicular bone. A Early stage. Bony nucleus dense and flattened antero-posteriorly. B Two years later. Bone texture restored; slight residual flattening.

Treatment. Despite the slow evolution of the bone changes prolonged treatment is not required. Good results follow symptomatic treatment. Usually all that is necessary is to rest the foot for 6–8 weeks in a walking plaster.

PAINFUL HEEL

The causes of painful heel are conveniently classified according to the site of the pain (Fig. 19.22).

Fig. 19.22 Eight causes of painful heel, with site of pain. 1. Disease of the calcaneus. 2. Arthritis of the subtalar joint. 3. Ruptured calcaneal tendon. 4. Calcaneal paratendinitis. 5. Post-calcaneal bursitis. 6. Calcaneal apophysitis. 7. Tender heel pad. 8. Plantar fasciitis.

DISEASE OF THE CALCANEUS

The calcaneus is subject, although rarely, to all types of infection of bone, the commonest being pyogenic infection (osteomyelitis). Occasionally it is the seat of a benign or malignant tumour. It may also be affected by other disorders of bone, such as Paget’s disease.

PAIN IN THE FOREFOOT (METATARSALGIA)

Pain in the forefoot is one of the commonest orthopaedic complaints. There are three main causes, of which the first is the most frequent:

Anterior flat foot (dropped transverse arch)

Permanent flattening of the transverse arch of the foot, with excessive weight-bearing pressure beneath the metatarsal heads, is the commonest cause of metatarsalgia. In most cases the primary cause is inefficiency of the intrinsic muscles of the foot.

Pathology. Even in normal feet the transverse arch is only a potential arch, not a constant one. But in the normal state the metatarsal heads can be raised from the ground at will by the action of the toes, held straight at the interphalangeal joints by the intrinsic muscles and flexed strongly at the metatarso-phalangeal joints by the intrinsic muscles in conjunction with the long and short flexors (Fig. 19.23A). Thus the weight is shared between the metatarsal heads and the toes. If the intrinsic muscles are inefficient the toes are unable to fulfil their important weight-sharing function and all the pressure falls upon the metatarsal heads (Fig. 19.23B). The excessive pressure leads to the formation of callosities.

Fig. 19.23 A Diagram to show the normal action of the toes in raising the metatarsal heads from the ground, whereby they share the weight with the metatarsal heads. This action is controlled mainly by the intrinsic muscles, which, by producing flexion at the metatarso-phalangeal joints and extension at the interphalangeal joints, cause the toes to press upon the ground, lifting the metatarsal heads. B If the intrinsic muscles are inefficient all the weight must be borne by the metatarsal heads.

Clinical features. The main complaint is of pain beneath the forefoot. There may be secondary symptoms from pressure of the shoes upon deformed toes. On examination the forefoot is often splayed, appearing broader than normal. There are callosities beneath some or all of the metatarsal heads. The toes are often curled. The patient is unable to raise the metatarsal heads from the ground by pressing downwards with the toes – an indication that the intrinsic muscles are inefficient.

Treatment. In patients under 50 worthwhile improvement can usually be gained by a prolonged course of physiotherapy, designed to strengthen the intrinsic muscles by special exercises. In older patients this treatment is seldom effective, and instead a trial may be made of soft moulded orthotic insoles to distribute the weight-bearing pressure over a wide area of the metatarsus. If there is a prominent callosity it may be pared away, with temporary relief.

If disability is severe, pain from local prominence of an individual metatarsal head in the sole may be relieved by osteotomy of the neck of the metatarsal and dorsal displacement of the head.

Stress fracture of a metatarsal bone (march fracture; fatigue fracture)

Stress or fatigue fractures are unusual in that there is no history of violence. The possibility of fracture may therefore be overlooked. A stress fracture of a metatarsal is not a common cause of pain in the forefoot but the possibility of its occurrence should be remembered.

Cause. The fracture is ascribed to long-continued or oft-repeated stress, hence the name as it is common in new military recruits subjected to excessive route marching; it has been likened to the fatigue fractures that sometimes occur in metals.

Pathology. The fracture usually affects the shaft of the second or third metatarsal bone, near its neck. It is no more than a hair-line crack, and there is no displacement of the fragments. In the process of healing a large mass of callus may form around the bone at the site of fracture. (This has occasionally been mistaken for a tumour.)

Clinical features. The complaint is of severe pain in the forefoot on walking. The onset is rapid but the patient is usually unable to ascribe it to an obvious cause. Enquiry may reveal, however, that he has recently done an unusual amount of walking or marching before the onset. On examination there is swelling at the dorsum of the forefoot, with marked and well-localised tenderness over the affected metatarsal bone.

Radiographs at first show only a faint hair-line crack which is easily overlooked (Fig. 19.24A), but after two or three weeks the callus surrounding the fracture is clearly visible and usually abundant (Fig. 19.24B).

Fig. 19.24 Stress fracture of second metatarsal. A shows the initial radiograph, taken a week after the onset of pain. The fracture is seen as a fine crack across the bone. shows the condition three weeks later, in the stage of healing. Abundant callus has formed about the site of fracture.

Treatment. The fracture heals spontaneously; so treatment is purely symptomatic. Indeed in some cases treatment is not needed; but if pain is severe immobilisation in a below-knee walking plaster for three or four weeks is advised.

Plantar digital neuritis (Morton’s metatarsalgia¹; interdigital neuroma)

This condition, which is primarily an affection of a digital nerve, is characterised typically by metatarsal pain combined with a radiating pain in the third and fourth toes.

Pathology. The underlying lesion is a fibrous thickening or ‘neuroma’ of the digital nerve of the 3–4 cleft just proximal to its point of division into terminal branches. It takes the form of a fusiform swelling, usually about a centimetre long, surrounding the nerve as it lies in the space between the heads of the third and fourth metatarsals (Fig. 19.25). Occasionally the nerve to the 2–3 cleft is the one affected. The cause of the fibrous thickening is uncertain.

Fig. 19.25 Fibrous thickening of an interdigital nerve, a characteristic feature of plantar digital neuritis (Morton’s metatarsalgia). The ‘neuroma’ is usually in the 3–4 cleft.

Clinical features. The patient is often a woman of middle age. She complains of pain in the forefoot on standing or walking. A characteristic feature is that the pain, arising in the metatarsal region, radiates forwards into the contiguous sides of the third and fourth toes, or to the fourth toe alone. Rarely, the cleft between the second and third toes is affected. The pain, like nerve pain in general, is piercing and disabling. Patients often state that they can relieve the pain by taking the shoe off and squeezing or manipulating the forefoot.

On examination the forefoot is often splayed, as in anterior flat foot. Sometimes a painful click can be elicited by compressing the metatarsal heads together from side to side, and upward pressure on the sole between the third and fourth metatarsal heads is painful.

Imaging. Plain radiographs are normal, but the abnormality of the nerve can be visualised with ultrasound or MRI scanning (Fig. 19.26) confirming the diagnosis.

Fig. 19.26 Morton’s neuroma shown on an axial T1 weighted MR scan of forefoot. The great toe is on the right of the image and the arrow indicates the small soft-tissue nodule in the interspace between the 3rd and 4th metatarsal heads.

Treatment. The patient should try first the effect of wearing a sponge-rubber metatarsal pad to support the anterior arch. If this fails to relieve the symptoms operative excision of the thickened segment of the nerve is recommended, though the patient must be warned that this leaves some residual numbness in the toe.

PLANTAR WART (Verruca pedis; verruca plantaris)

Plantar warts may occur in any part of the sole of the foot, including the under surface of the heel. They are like warts elsewhere, except that they do not project beyond the skin surface. They are distinct from plantar callosities, which are simply localised thickenings of the skin at points of excessive pressure.

Cause. A virus infection is responsible.

Pathology. A wart is a simple papilloma, growing outwards from the basal layers of the skin. It is prevented by the pressure of weight-bearing from projecting much beyond the skin surface, but the surrounding skin is thickened, so the wart may have a total depth of up to half a centimetre. It slowly enlarges, but seldom reaches a diameter of as much as a centimetre.

Clinical features. The chief complaint is of severe localised pain on walking. On examination the skin surrounding the wart is thickened and therefore raised. The wart, a little darker in colour and with a mosaic surface, is seen in the centre of the raised area (Fig. 19.27). Its edge is clearly demarcated from the surrounding skin: this can be discerned easily if the skin is stretched away from the wart, when a tiny cleft becomes apparent between wart and skin. There is always marked local tenderness on pressure over the wart.

Fig. 19.27 Plantar wart. Note the clearly circumscribed outline and the slight cleft when the skin is stretched away from the wart.

Diagnosis. The main difficulty is to distinguish warts from callosities. Warts occur anywhere on the sole, callosities only over points of pressure. Warts are also much more tender than callosities. But the most reliable distinguishing feature is that a wart has a mosaic surface and a clearly defined margin with a potential cleft between it and the skin (Fig. 19.28A), whereas a callosity blends imperceptibly with the surrounding normal skin (Fig. 19.28B).

Fig. 19.28 A Diagrammatic section of a plantar wart. It is clearly demarcated from the surrounding skin. B Diagrammatic section of a callosity. It blends imperceptibly with the surrounding normal skin.

Treatment. The local application of appropriate caustics is often successful. If this treatment fails the wart should be curetted out and the base lightly cauterised.

CALLOSITIES

A callosity is simply a localised thickening of the skin in response to abnormal pressure. It is nearly always secondary to a pre-existing disorder of the foot.

Plantar callosities are callosities on the sole of the foot. They occur under a prominent bone. They are commonest beneath the metatarsal heads when deficient intrinsic muscles prevent the toes from taking their proper share in weight-bearing (anterior flat foot, p. 449). They are also common beneath the base of the fifth metatarsal in patients who for any reason walk with the foot inverted.

Callosities on the toes often take the form of localised thickenings, when they are termed corns. They are caused by pressure against the shoe, and they are especially common when the dorsum of a toe is made unduly prominent by a fixed flexion deformity, as in hammer toe (see Fig. 19.33A, p. 459).

Treatment. The treatment is mainly that of the underlying condition. Palliative measures include paring of excess epidermis (preferably by a chiropodist, though simple instruments are available for use by the patient), and sponge-rubber padding to distribute the weight-bearing pressure over a wider area.

GANGLION

Ganglia are common on the dorsum of the foot and around the ankle. They are similar in all respects to the ganglia that occur at the back of the wrist and hand. They consist of thin-walled sacs filled with glairy viscous fluid, and the fibrous wall is usually connected deeply with a ligament, tendon sheath, or joint capsule. Clinically, a ganglion appears as a fluctuant subcutaneous swelling, which may be either soft or tense. If it causes trouble it should be excised.

HALLUX VALGUS

In hallux valgus the great toe is deviated laterally at the metatarso-phalangeal joint. It is common in women past middle age, and is not infrequent even in young women.

Cause. In some cases, particularly in children and adolescents, hereditary factors are responsible. But in most the deformity is caused by the toes being persistently forced laterally by enclosure in narrow pointed shoes. The wearing of high heels favours the development of hallux valgus because the forefoot is forced into the narrow pointed part of the shoe.

Pathology. Outward deviation of the great toe is the most obvious feature of the deformity, but a further, almost constant feature is that the first metatarsal is deviated medially, so that the gap between the heads of the first and second metatarsals is unduly wide (metatarsus primus varus). Indeed this may often be the primary defect. After several years two secondary changes occur. One is the formation of a thick-walled bursa (bunion) over the medial prominence of the metatarsal head; this may become inflamed, occasionally with suppuration. The second, a later development, is osteoarthritis of the metatarso-phalangeal joint consequent upon its mal-alignment (see Fig. 19.30B).

Clinical features. The patient is nearly always a woman, who is often at or past middle age when she seeks advice but may sometimes be a young woman or even an adolescent girl. The early symptoms arise from tenderness over the bunion from pressure against the shoe. There is also difficulty in getting comfortable footwear. Later, additional symptoms arise from osteoarthritis of the metatarso-phalangeal joint, and from flattening of the transverse arch (anterior flat foot, p. 449), which is a common associated deformity.

On examination the deformity is obvious at a glance (Figs 19.29A and 19.30A). The skin over the prominent joint is hard, reddened, and tender. Often a thick-walled bursa can be felt, and occasionally it is distended with fluid (Fig. 19.30B). In relatively early cases metatarso-phalangeal joint movements are free and painless, but in severe cases of many years’ duration the secondary osteoarthritis makes movement limited and painful. In late cases the forefoot is often flat and splayed, and the toes may be severely curled (Fig. 19.30A).

Fig. 19.29 A Hallux valgus of moderate degree in a woman of middle age. B After correction by displacement osteotomy of the neck of the first metatarsal. Normal appearance restored.

Fig. 19.30 A Severe hallux valgus. The great toe is over-riding the deformed second toe. B Diagram showing the prominent metatarsal head with overlying bunion, and osteoarthritis from long-standing mal-alignment of the joint.

Treatment. In mild cases treatment is not required, but footwear must be selected with care to obtain adequate width. It may also be worthwhile to protect the bunion with pads of felt, and to wear a wedge of plastic foam between the great toe and the second toe to reduce the deformity.

If disability is troublesome operation is advisable. There is much variation of opinion among different surgeons on the choice of treatment. Mention will be made here of only four of the many methods that are available.

Trimming of ‘exostosis’. When the deviation of the toe is slight, but troublesome symptoms arise from localised prominence or ‘exostosis’ of the first metatarsal head at the medial side of the foot, it may sometimes be sufficient simply to excise the bursa and chisel away the medial prominence of the metatarsal head without disturbing the joint itself. There is, however, a tendency for the symptoms to recur after this operation, and in general the results are so disappointing that the operation is now seldom recommended.

Displacement osteotomy of the neck of the first metatarsal bone. This is illustrated in Fig. 19.31. After division of the neck of the metatarsal the head fragment is displaced markedly laterally (Fig. 19.31B). The outward shift of the metatarsal head eliminates the prominence of the ‘exostosis’ without the need for its removal. The soft tissues between the heads of the first and second metatarsals are also relaxed, allowing permanent reduction of the subluxation at the first metatarso-phalangeal joint. After operation the toe may be immobilised in plaster for 6 weeks or fixed with a screw to ensure union at the site of osteotomy without loss of position.

Fig. 19.31 Displacement osteotomy of the neck of the first metatarsal. A Before operation. Note the wide gap between the first and second metatarsals. B After division of the first metatarsal through its neck the head fragment is displaced markedly laterally, so that its medial prominence (the ‘exostosis’) disappears. The metatarso-phalangeal subluxation is automatically reduced. Remodelling (interrupted line) alters the shape of the metatarsal and the intermetatarsal gap is narrowed.

By a process of remodelling, the alignment of the first metatarsal is gradually altered after operation so that it lies closer to the second metatarsal (Fig. 19.31B).

In this operation the joint itself is left undisturbed, indeed unopened. The operation gives good results in patients with relatively slight deformity (Fig. 19.29B): it does not shorten the toe appreciably or impair active movement, and it is therefore particularly suitable for young patients who wish to lead an energetic life.

Excision arthroplasty of the first metatarso-phalangeal joint by Keller’s¹ method is widely used in elderly patients. The object is to create a flail, freely movable false joint between the first metatarsal and the proximal phalanx, with correction of the mal-alignment. This is done by excising the proximal half of the proximal phalanx so that a gap is left between the two bones: at the same time the bursa is excised and the medial prominence of the metatarsal head is smoothed off with a chisel (Fig. 19.32A).

Fig. 19.32 Hallux valgus. A Excision arthroplasty (Keller’s operation): removal of the proximal half of the proximal phalanx. The resulting gap fills with flexible fibrous tissue. The bursa and the underlying prominence of the metatarsal head have also been removed. B Radiograph 10 years after Keller’s operation for hallux valgus.

The space created by excision of the base of the phalanx fills with rubbery fibrous tissue, and a false joint forms which allows a reasonable range of movement (Fig. 19.32B).

This operation leaves the great toe markedly shorter than normal and rather floppy, with poor active control over toe movements. The patient should be warned about this in advance. Nevertheless the main symptoms are relieved and the result is usually satisfactory in elderly patients who do not wish to walk long distances or to indulge in athletic pursuits.

Arthrodesis of the metatarso-phalangeal joint of the hallux in a position of slight extension allows full and permanent correction of the valgus deformity, even if it is very severe – but at the cost of loss of mobility.

When severe hallux valgus in an elderly patient is associated with flattening of the transverse arch and marked clawing of the toes (see Fig. 19.30A), operation of any type may be disappointing and it may be wiser to rely upon well-made surgical shoes.

HAMMER TOE

The term hammer toe denotes a fixed flexion deformity of an interphalangeal joint.

Cause. Presumably an imbalance of the delicate arrangement of flexor and extensor tendons is responsible; but the precise explanation of its occurrence is unknown. Hammer deformity, especially of the second toe, is often associated with severe hallux valgus (see Fig. 19.30A).

Pathology. The proximal interphalangeal joint of the second toe is that most commonly affected. The affected joint is sharply angled into flexion. Secondary contracture of the plantar aspect of the joint capsule fixes the deformity, and a callosity usually forms over the dorsum of the flexed joint, from pressure against the shoe (Fig. 19.33A).

Fig. 19.33 A Hammer toe: the typical deformity, with callosity over the prominent proximal joint. B Peg arthrodesis, for correction of hammer toe.

Clinical features. Typically the deformity affects only one toe – usually the second. In the characteristic deformity the proximal interphalangeal joint is in fixed flexion, and the distal interphalangeal joint, though still mobile, rests in compensatory hyperextension (Fig. 19.33A). The symptoms, if any, are caused by the overlying callosity or ‘corn’ or pain from bearing weight on the end of the toenail.

Treatment. If symptoms are slight the deformity may be accepted, or conservative treatment by protective felt pads may be sufficient. In severe cases operation gives gratifying results. The joint surfaces are excised and the joint is arthrodesed or pseudarthrosed in the corrected position (Fig. 19.33B).

UNDER-RIDING TOE (Congenital curled toe)

Children are often brought for advice because one of the smaller toes, often the fourth, is curled inwards and lies beneath the adjacent toe. The condition does not cause any symptoms during childhood, and it should be left alone until adolescence or early adult life, when the toe can easily be straightened if it begins to cause symptoms. Similar principles apply to the management of over-riding toe.

RHEUMATOID ARTHRITIS OF THE TOE JOINTS

Deformity of the forefoot is a common cause of pain and disability in rheumatoid arthritis, but may be underdiagnosed because of the more visible problems in the patient’s other lower limb joints. Characteristically the metatarso-phalangeal joints are most affected, with destruction of articular cartilage, dorsal subluxation of the phalanges and clawing of the toes. Painful skin callosities then develop on the sole beneath the prominent metatarsal heads and on the dorsum of the flexed toes from the pressure of footwear.

In the early stages radiographs show only joint narrowing and marginal erosions. In the later stages there may be subluxation or dislocation of the metatarso-phalangeal joints with marked destruction of bone (Fig. 19.34).

Fig. 19.34 Severe toe deformities from long-established rheumatoid arthritis. Note the subluxation of the metatarso-phalangeal joint of the great toe, and dislocation of several of the lesser toes at the metatarso-phalangeal joints. Some of the metatarsal heads show erosion of bone.

Treatment. Minor deformity may be managed by the provision of moulded insoles and broad-fitting shoes with soft uppers. In advanced disease with fixed painful deformities forefoot reconstruction is advisable and should normally precede surgery for the hindfoot or knee joints to reduce the risk of ulceration and infection. There are a number of different operative procedures to restore the forefoot alignment by excision of the bases of the proximal phalanges and trimming of the metatarsal heads (excision arthroplasty). Following wound healing, patients may require the provision of orthotic insoles and surgical shoes to allow them to walk in comfort.

OSTEOARTHRITIS OF THE TOE JOINTS

In practice, osteoarthritis in the toes is seen commonly only in the metatarso-phalangeal joint of the great toe. This has been termed hallux rigidus. Occasionally the metatarso-phalangeal joint of one of the smaller toes is affected, usually as a late result of Freiberg’s disease of a metatarsal head (p. 462).

Hallux rigidus

This is osteoarthritis of the metatarso-phalangeal joint of the great toe. Like osteoarthritis elsewhere, it is caused by wear and tear, but previous injury or disease of the joint is an important predisposing factor.

Pathology. The changes are like those of osteoarthritis in other joints. The articular cartilage is gradually worn away from both surfaces of the joint until eventually the subchondral bone is exposed. The exposed bone becomes hard and glossy (eburnation). The marginal bone hypertrophies to form osteophytes, which often cause obvious thickening, especially at the dorsum of the toe.

Clinical features. The complaint is of pain in the base of the great toe on walking. On examination the metatarso-phalangeal joint is palpably thickened from osteophyte formation. If an osteophyte is especially prominent on the dorsal or medial aspect of the joint a thick-walled bursa (bunion) may form over it; occasionally the bursa is distended with fluid. Flexion and extension of the toe at the metatarso-phalangeal joint are restricted – usually markedly so by the time the patient seeks advice (Fig. 19.35A). Forced dorsiflexion of the painful joint on walking is the main source of the disability. (It should be remembered that the normal range of dorsiflexion at the metatarso-phalangeal joint of the great toe is nearly 90°.)

Fig. 19.35 Hallux rigidus. A shows the marked impairment of dorsiflexion. B shows the radiographic changes typical of osteoarthritis, namely narrowing of the cartilage space, subchondral sclerosis, and the formation of osteophytes.

Radiographs confirm the presence of osteoarthritis. The cartilage space is narrowed, the subchondral bone tends to be sclerotic, and there is osteophytic spurring of the joint margins (Fig. 19.35B).

Treatment. In mild cases treatment is not required. When treatment is called for, conservative measures are usually worth a trial first. A metatarsal bar should be fitted beneath the sole of the shoe at the metatarso-phalangeal level. This acts as a rocker in walking, and so reduces the dorsiflexion required of the toes when weight is brought onto the forefoot from the heel.

When the disability is severe operation should be advised. One method is to create a flail joint by excision of the base of the proximal phalanx (Keller’s arthroplasty), as for hallux valgus. Many surgeons find, however, that arthrodesis of the metatarso-phalangeal joint (see Fig. 4.1B) in a position of slight extension gives better results, with complete relief of pain.

GOUTY ARTHRITIS OF THE GREAT TOE JOINTS (General description of gouty arthritis, p. 143)

The joints of the great toe are those most often affected in gout, especially in the first attack.

Clinical features. The patient is usually over 40, and more commonly a man than a woman. There is a sudden onset of severe pain in the great toe, often during the night.

On examination the toe is swollen, red, and extremely tender. Joint movements are impossible because of pain. There is sometimes slight pyrexia. The patient will usually recall previous similar attacks lasting a few days, with freedom from pain in the intervals. Radiographs are normal in the early stages. Investigations: There is sometimes a mild leucocytosis. The plasma urate level is usually raised.

Chronic gout. In this form deposits of sodium biurate in and around the joints of the great toe lead to persistent nodular thickening. Radiographs show rounded areas of transradiance in the bone ends; these represent deposits of sodium biurate (which is transradiant) in the subchondral bone.

Diagnosis. Acute gout is easily mistaken for acute infective arthritis. Features suggestive of gout are: a raised plasma urate level; a history of previous attacks, with symptom-free intervals; and the presence of tophi in the ears or elsewhere.

Course. Gout usually occurs in recurrent attacks. In the early years, an acute attack subsides within a few days, leaving the joint clinically normal. In chronic gout the joint is gradually disorganised, causing permanent disability.

Treatment. Acute attacks respond to selected non-steroidal anti-inflammatory drugs such as indometacin or naproxen, begun in high dosage which is reduced after two or three days, or to colchicine. Meanwhile the foot should be rested, and the toe should be protected from pressure by a bulky wool dressing. The treatment of recurrent and chronic gout was detailed on page 145.

FREIBERG’S DISEASE OF A METATARSAL HEAD¹ (Metatarsal osteochondritis)

Freiberg’s disease of a metatarsal head is regarded by some as an example of osteochondritis juvenilis (p. 130) and by others as osteochondritis dissecans (p. 153). It may therefore be advisable to use the non-committal eponymous title for the present. The essential feature of Freiberg’s disease is partial necrosis and fragmentation of a metatarsal head, which may become deformed under the pressure of weight-bearing. It is an uncommon condition.

Pathology. The epiphysis of one of the metatarsal heads – nearly always the second or third – is the part affected. The bony nucleus becomes necrotic and granular. Part of the articular surface separates, usually remaining attached only by a hinge of articular cartilage. While it is in this crumbly state the metatarsal head is crushed by the pressure against it of the base of the proximal phalanx of the toe. The articular surface of the metatarsal head thus loses its normal dome-shaped contour and becomes flat (Fig. 19.36). After about 2 years the texture of the bone returns to normal, but flattening of the articular surface remains. Later, the distortion of the joint surface often leads to osteoarthritis.

Fig. 19.36 Radiograph of forefoot showing the typical appearance of Freiberg’s disease in the second metatarsal. There is an abnormal appearance of the metatarsal head, which is flattened and sclerotic due to osteochondritis.

Clinical features. At the time of onset the patient is 14 to 17 years old. There is pain in the affected metatarso-phalangeal joint, worse on standing or walking. On examination there is slight thickening in the region of the head of the metatarsal, which is tender on pressure. Movements of the metatarso-phalangeal joint are slightly restricted and painful. Radiographs reveal the nature of the trouble, though at first the changes are very slight and may be overlooked. Later the head of the metatarsal appears fragmented, with patches of increased density. Finally, the articular surface is flattened, so that the end of the bone appears square-cut instead of round (Fig. 19.36).

Treatment. When the diagnosis can be made in the early stage – before marked radiographic changes are apparent – operation offers a hope of preventing permanent distortion of the joint surface. Through a window cut in the dorsal surface of the metatarsal neck the necrotic bone of the head is curetted out and replaced by cancellous chip bone grafts, packed firmly enough to restore the normal dome-shaped contour of the articular surface. Thereafter the toe is supported in a plaster cuff for 6 weeks.

When deformity of the metatarsal head is already well established at the time of diagnosis attempted restoration of the articular surface is of no avail. Expectant treatment is then recommended. If pain is troublesome rest in a walking plaster for 2 months may afford relief; but if disabling osteoarthritis develops later the head of the metatarsal should be excised.

INGROWING TOE NAIL (Embedded toe nail)

Ingrowing toe nail is common only in the great toe.

Cause. Some persons have toes that are prone to develop ingrowing toe nail. But the main causative factors are incorrect cutting of the nail, pressure on the nail-wall (lateral skin fold) by the shoe or by the adjacent second toe, and accumulation of dirt and sweat.

When the nail is cut its sides should be left long enough to project beyond the terminal pulp (Fig. 19.37A): if it is cut too short a sharp corner of nail lies in contact with the lateral skin fold (Fig. 19.37B), and this corner may tend to embed itself in the skin, especially if there is local pressure at the side of the toe. In the presence of dirt and sweat, infection is then liable to arise.

Fig. 19.37 A Nail cut correctly. B Nail cut too short: corners dig into pulp. C Operation for ingrowing toe nail. A strip of nail is avulsed and its re-growth is prevented by excision of a segment of the germinal matrix. D Operation for permanent ablation of the whole nail. After avulsion of the nail, only the germinal matrix need be excised to prevent re-growth. The raw area is covered by advancing the proximal skin flap.

Clinical features. The lesion may be at the medial or (more commonly) the lateral border of the nail, or both. There is pain at the affected anterior corner of the nail. On examination the skin fold is inflamed, and there may be local suppuration where the corner of the nail digs into the skin.

Treatment. In mild cases conservative treatment may suffice. Pledgets of gauze soaked in alcohol (surgical spirit) are tucked beneath the corner of the nail twice a day, and the nail is allowed to grow until its edges project beyond the skin folds (Fig. 19.37A).

In long-standing cases operation is advisable. If only one side of the nail is involved it is sufficient to avulse a strip of nail at the affected side and then to prevent re-growth of this part. Since the nail is formed only from the germinal matrix – the proximal curved segment of the nail bed that corresponds to the lunula – and not from the nail bed as a whole, it is necessary to remove only an appropriate piece of the germinal matrix to prevent regrowth (Fig. 19.37C).

In the worst cases, with infection at both sides of the nail, permanent ablation of the entire nail by excision of the whole of the germinal matrix is more satisfactory (Fig. 19.37D). The small raw area that remains can be covered simply by advancing a dorsal skin flap, based proximally and with its free edge at the nail fold.

SUBUNGUAL EXOSTOSIS

A subungual exostosis is a bony outgrowth from the dorsal surface of the distal phalanx of a toe – usually the great toe. It projects upwards and forwards between the tip of the nail and the terminal pulp. The nail is raised and deformed, and the skin of the pulp overlying the outgrowth is thickened and hard. There is sharp pain when pressure is applied over the nail or terminal pulp. Radiographs show the exostosis, which is seen best in the lateral projection.

Treatment. The exostosis should be excised through a terminal incision just beyond the tip of the nail.

ONYCHOGRYPOSIS

Translated from the Greek, this means ‘hooked nail’. The term is descriptive. The nail – usually of the great toe – is enormously thickened, discoloured and curved, eventually resembling a miniature ox-horn (Fig. 19.38). The condition is due to a chronic fungal infection of the nail.

Fig. 19.38 Onychogryposis.

Treatment. Simple removal of the nail is an adequate temporary measure; but the new nail will become similarly deformed. The chance of this is reduced with appropriate oral antifungal therapy. For permanent cure the nail bed must be ablated by excision of the germinal matrix, as described in the section on ingrowing toe nail (p. 464).