Traumatic disorders of the nail

The Scar Solution Natural Scar Removal

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Rodney PR Dawber and Ivan Bristow

Major trauma

Repeated microtrauma of the nail apparatus The painful nail Further reading

This chapter looks at three distinct aspects of trauma, under the headings:

1 Major trauma (involving any digit).

2 Repeated microtrauma.

3 The painful nail.

MAJOR TRAUMA

This section considers major trauma, single overwhelming injury, necessitating only minor 'office' surgery. Complex laceration and most of the traumatic abnormalities are beyond the intended scope of this book. Damage from acute trauma may have immediate and/or delayed effects.

Haematoma

Acute subungual haematoma is usually obvious (Figures 9.1-9.3), occurring shortly after painful trauma, for example a car door slammed on fingers or a heavy object dropped on a toe nail. The blood that accumulates under the nail plate intensifies the pain, which is severe. This prevents delay in the regrowth of the nail and secondary onychodystrophy resulting from pressure on the matrix caused by the accumulated blood. The technique used to drain the blood depends on the size of the haematoma.

Partial haematoma

Splinter haemorrhages are produced by the disruption of small vessels of the dermal ridges of the nail bed. They are more common in males than in females and in the first three fingers of each hand. With increased trauma, more dermal ridges are involved, resulting in ecchymoses. Subungual haematoma usually appears shortly after trauma, but if the injury occurs below the proximal nail fold, the haemorrhage may not be visible for

2-3 days. Haemorrhage in the matrix is incorporated into the nail plate; bleeding distal to the lunula remains subungual.

Figure 9.1

Severe traumatic haematoma.

Figure 9.2

Matrix haematoma migrating distally into the nail bed.

Figure 9.2

Matrix haematoma migrating distally into the nail bed.

Total haematoma

Haematoma involving more than 25% of the visible nail is a warning sign of severe nail bed injury and possible underlying phalangeal fracture; an X-ray is therefore mandatory.

Figure 9.3

Haematoma causing partial onychomadesis.

Figure 9.3

Haematoma causing partial onychomadesis.

Potential development of osteterminalisitis (infection under the nail) is a hazard, as such infection can spread quickly, affecting the underlying nail structures.

Nail shedding

Nail shedding may occur acutely either by direct force or following subungual haematoma; it may also appear some months after the event.

Acute paronychia

Acute paronychia may result from a penetrating thorn or splinter into the nail fold. Infection is usually painful and due to Staphylococcus aureus. Systemic antibiotic therapy is indicated at an early stage. If response does not occur within 2 days, then removal of the proximal portion of the nail plate is indicated.

Pyogenic granuloma

Pyogenic granuloma (Figure 9.4) is a benign haemangioma which typically follows skin injury. It may develop in the nail bed after a penetrating wound of the nail plate. Tenderness and a tendency to bleed easily are characteristic features. Pyogenic granuloma may be removed by excision at its base, followed by the use of aluminium chloride solution as a haemostat. Histological examination is essential to rule out amelanotic melanoma.

Delayed effects of major trauma

These are numerous (Figures 9.5-9.8). Trauma-induced Beau's line accompanied by pyogenic granuloma of the proximal nail folds of the affected fingers from trauma on the palm and the arm has been reported. Delayed effects of major trauma include permanent damage of the nail matrix, sometimes with unequal growth of different sections of the nail plate. Damage to the matrix may result in a split extending along the entire length of the nail, or a longitudinal prominent ridge, and may even result in ectopic nail due to the altered position of the matrix following the trauma, Trauma to the proximal nail fold may be responsible for the formation of pterygium. Longitudinal melanonychia following acute trauma is rare in white individuals. Hook nail is observed when the nail bed is shortened after distal section of the bony phalanx. Any traumatic force to the distal phalanx can result in bony changes affecting the future nail structure. An example of this is the subungual exostosis which often leads to onychocryptosis with a 'tented' hallux nail whose lateral and medial edges impinge on their corresponding nail grooves (Figure 9.9). Significant injury was thought to be associated with the development of some cases of subungual melanoma; this is still debatable.

Figure 9.4

Pyogenic granuloma.

Figure 9.5

Post-traumatic fissures.

Figure 9.6

Post-traumatic nail ridge.

Figure 9.7

Post-traumatic nail dystrophy—pterygium scar.

Figure 9.7

Post-traumatic nail dystrophy—pterygium scar.

Figure 9.8

Traumatic matrix distortion and nail plate dystrophy—ectopic nail.

Figure 9.9

'Tented' nail over a bony exostosis.

Figure 9.9

'Tented' nail over a bony exostosis.

REPEATED MICROTRAUMA OF THE NAIL APPARATUS

Chronic trauma implies repeated minor injury often unnoticed by the patient. A history of nail trauma as a cause of onychodystrophy can therefore be more difficult to elicit. Repeated microtrauma to the toe nail is a frequent cause of nail disorders, and when assessing them it is important to take a full view of the whole foot and lower limb. All too often, practitioners treat the foot and nail as static anatomical structures when common problems arise as a result of their dynamic functions. It is only when this is taken into account that the distinct differences between finger and toe nails becomes apparent. Microtrauma to the toe nail frequently arises as a result of:

• foot function

• foot and digit shape

When presented with a toe nail problem, assessment of the foot and toes should always include the weight bearing and walking by the patient to fully appreciate foot and toe position.

Foot function

In simple terms the human foot has evolved to carry out a specific function—to assist smooth and efficient locomotion. In undertaking this task the foot has developed the ability to alter its structure within a single footstep. To understand this we must briefly look at the normal gait cycle (Figure 9.10). During normal walking, the first stage (heel strike) begins when the heel comes into contact with the ground. To permit shock absorption the foot must become a flexible unit. It does this by pronation (a triplanar movement occurring mainly at the subtalar and midtarsal joints). This may be recognized by eversion of the calcaneum, lowering of the arch and slight elongation of the foot. Subtalar joint pronation unlocks the midtarsal joint so that effectively the foot is flexible to accommodate ground reaction at heel strike. The pronation occurs until the whole foot is flat to the floor (midstance or full foot). In order for this foot to take the full body weight as the opposite foot leaves the ground, it must now become a rigid unit. Once the opposite limb has passed the plantigrade foot, and undergoes heel strike, the foot begins propulsion. The heel lifts, so that body weight is shifted onto the forefoot and the toes. In order to stabilize the foot and balance the whole body forward, the foot becomes supinated (this is a movement involving the subtalar and midtarsal joints whereby the calcaneum inverts, the arch is raised and the foot is effectively shortened). This movement effectively locks the foot into rigidity, allowing a stable platform for propulsion.

Many abnormal foot functions can upset this sequence of supination-pronation-resupination. In terms of toe nail pathology, these predominantly occur around the propulsive phase of the gait cycle. If for any reason the foot has been unable to supinate to an adequate degree, there may not be sufficient rigidity and so propulsion occurs on a flexible foot. So major forces may be dissipated through the forefoot. When repeated many hundreds of times a day, this can have adverseeffects on the digital area, especially when interacting with footwear. If a foot is excessively pronating on propulsion, the foot will elongate (as part of pronation) so the distal area will be subject to trauma if the footwear depth is inadequate in length (Figure 9.11). Control of excess pronation may be obtained by way of prescribed orthoses in footwear.

Foot and digit shape

Within any population there is a great variation in foot shape and it is likely that this shape willchange with the effects of ageing and disease. The hallux is the digit most commonly affected by traumatic disorders. Hallux valgus (Figure 9.12) is a common orthopaedic disorder which may lead to nail problems. Gradual medial rotation of the digit occurs at the same time the hallux deviates laterally. This deformity may cause pronounced changes in the nail apparatus such as hyperkeratotic build-up along the edge of the tibial nail sulcus (Figure 9.13) and ingrowing toe nail. Lateral deviation of the hallux may lead to displacement of the second toe, which subsequently may be displaced dorsally. Counter pressure from the shoe can reflect pressure back, causing further nail changes (Figure 9.14).

Hallux rigidus is another common condition in which there is reduction in the range of motion at the first metatarsophalangeal joint. It is characterized by enlargement of the first metatarsal head and a general stiffening of the joint; motion is obtained at the nearest functional joint—the interphalangeal joint of the hallux. Over time the distal phalanx becomes permanently dorsiflexed; the nail often protrudes dorsally and is open to trauma from footwear, leading to possible onychauxis or onychocryptosis (Figure 9.15).

Figure 9.10

The positions of the foot during the normal gait cycle.

Figure 9.10

The positions of the foot during the normal gait cycle.

Figure 9.11

Transparent shoe demonstrating effect of shallow toe box: the hallux is compressed into the upper of the shoe.

Figure 9.11

Transparent shoe demonstrating effect of shallow toe box: the hallux is compressed into the upper of the shoe.

Figure 9.12

Hallux valgus.

Figure 9.13

Nail dystrophy due to hallux valgus. (Courtesy of B.Schubert.)

Figure 9.13

Nail dystrophy due to hallux valgus. (Courtesy of B.Schubert.)

Figure 9.14

Overriding second toe. Involution can be seen in the hallux nail plate.

Figure 9.14

Overriding second toe. Involution can be seen in the hallux nail plate.

Problems with the lesser digits can also adversely affect the nail apparatus (Figure 9.16); these can be congenital or acquired. Frequently affected are feet with the second toe longer than the first, which can lead to the longer toe suffering increased trauma from the end of a shoe or by stubbing and secondary onychomycosis. Longer toes may suffer trauma in the shoe, leading to subungual haematoma and consequent long-term changes in the nail structure.

Sporothrix Roses

Figure 9.15

Hallux rigidus with compensatory hyperextension of the distal phalanx. Early onychocryptosis is evident.

Figure 9.15

Hallux rigidus with compensatory hyperextension of the distal phalanx. Early onychocryptosis is evident.

Figure 9.16

Various lesser digit deformities commonly seen in the foot, which may cause nail dystrophy, (a) hammer; (b) claw; (c) mallet; (d) retracted toe.

Figure 9.16

Various lesser digit deformities commonly seen in the foot, which may cause nail dystrophy, (a) hammer; (b) claw; (c) mallet; (d) retracted toe.

Other digital deformities of the lesser toes arise as a consequence of footwear, trauma, disease or abnormal foot function. During locomotion, rectus alignment of the toes is required during heel lift to permit the long extensors of the anterior leg group to raise the foot for propulsion. Intrinsic muscles of the foot are vital for normal digital alignment and are easily disturbed by excessive pronation and supination, along with diseases that may affect the nerves innervating them, such as diabetes or poliomyelitis. Consequently during gait the toes become destabilized and adopt various deformities.

Footwear

In older age groups, chronic foot disorders are far more prevalent in women. In part this is attributable to footwear and fashion. A UK study of 9-year-old children's feet found that 25% of girls compared with 1 % of boys wear unsuitable shoes, notably with a too narrow toe box. Improper fitting often continues into adult life, with women consistently wearing shoes that are 'smaller than their feet'. Assessment of the footwear should help to establish causes of traumatic nail dystrophies. In order to do this, it is important to assess the shoes that the patient wears most often and not those just worn to the consultation! The main causes of nail problems include:

• poor fitting of footwear

• inadequate footwear design or construction

• excessive wear to shoes.

When looking at shoe fit, areas of prime importance are:

1 Heel height—generally if heels are too high, the foot is forced forward into the toe box with every step, traumatizing the anterior part of the foot, especially around the nail apparatus and apices. The higher the heel, the more damage is likely to 3 occur. It has been the experience of the authors that heel heights greater than 30-35 mm can yield unwanted effects.

2 Lack of a suitable fastening—a foot in a shoe without adequate fastening suffers in that the foot is free to move unrestrained in the shoe and inevitably (as with high heels) it tends to slip forward into the toe box region of the shoe, traumatizing the distal aspect. Laces are by far the best method of fastening a shoe. The higher the laces come up from the front of the shoe, the more restraint and support is given to the foot. With patients who, because of arthritis, cannot reach or tie laces, Velcro straps make a reasonable substitute.

3 Poor toe box design—in order to restrict rubbing and other trauma to the forefoot and nails, a good toe box is a vital feature. Adequate depth and width ensure no undue pressure is placed on the digital areas (Figure 9.17); allied with a suitable fastening this ensures that the foot stays well back from the tip of the shoe and into the heel. Modern shoes are still produced with inadequate width or depth in the toe box area. One can often see the effects of this when toe outlines are visible from the outside of the shoe. It is wise to feel inside the upper of the shoe; one can often feel a dent or a tear in the lining corresponding to the affected digit. The nail itself can give other clues. A nail with unusual pigmentation may

Figure 9.17

(a) Shoes positioned tip to tip, to demonstrate difference in toe box depths, (b) Shallow toe box design contributes to nail problems: a subungual haematoma due to pressure and rubbing from the shoe toe box.

Figure 9.17

(a) Shoes positioned tip to tip, to demonstrate difference in toe box depths, (b) Shallow toe box design contributes to nail problems: a subungual haematoma due to pressure and rubbing from the shoe toe box.

Figure 9.18

A seamless fronted shoe.

have acquired this from rubbing on the leather of new shoes. More commonly, though, a single toe nail with a highly polished sheen is the result of continuous rubbing on the soft upper of a shoe.

4 Seams that run over the toe box region of the shoe to give an aesthetic touch can be the cause of problems. Inside the shoe, the stitching producing the seam may be readily felt in the shoe upper, impinging on the toe area; such stitching is best avoided (Figure 9.18).

5 Shoes that are too long or without a suitable fastening (slip-on) can often lead to increased nail trauma as, to compensate for the excessive movement, toes become clawed to maintain ground contact and increase stability.

Other factors

When looking at causative factors of nail problems one must always consider the

Figure 9.19

Nail unit injury in a diabetic patient with severe vascular disease; this injury was caused by the swift removal of a sticking plaster.

Figure 9.19

Nail unit injury in a diabetic patient with severe vascular disease; this injury was caused by the swift removal of a sticking plaster.

patients' circumstances. Toe nail problems in the aged can be particularly distressing. Not only are they complicated by reduced circulation and sensation, with all the dangers to the foot that this can entail (Figure 9.19), but poor eyesight and decreased manual dexterity in the elderly patient contribute to nail management difficulties. In addition, reduced mobility in the joints of the lower extremity makes it difficult to reach the foot for nail care.

The amount of time a person spends on their feet may affect the severity of the nail problem. Moreover, the footwear worn during these periods will be crucial. Occupational footwear is notorious for precipitating such problems. Occlusive footwear worn for long periods can lead to the retention of excessive perspiration (Figure 9.20). This may predispose to skin infection, which in time, may go on to affect the nail and surrounding tissues. This is often seen in manual workers whose job entails wearing rubber or plastic boots. The transportation and construction industries provide the highest incidence of foot injuries. Since the introduction of steel toe-cap shoes

Figure 9.20

A clear shoe showing the extent of perspiration.

the incidence has been reduced, but even these are not without their problems. The rigidity of the toe box has meant that incorrectly fitting boots have led to toe and nail injuries as a result of their design.

In order to reduce pressures across the digital areas various orthopaedic devices may be used. Where foot mechanics are considered to be the cause, functional orthoses may be prescribed to control excessive pronatory forces and prevent deterioration (Figures 9.219.23). Changes in footwear style are also often advisable. In addition local digital pressures may be reduced by the use of cushioning insoles to reduce repeated microtrauma. Silicone digital appliances may be used to correct or realign digits and so relieve abnormal forces around the nail unit.

Figure 9.20

A clear shoe showing the extent of perspiration.

Reducing microtrauma to the nail unit

Figure 9.21

Various orthoses which may correct abnormal foot function and digital alignment.

Figure 9.21

Various orthoses which may correct abnormal foot function and digital alignment.

Figure 9.22

Figure 9.23

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