Degloving injuries of the hand.

Avulsion of skin from the hand or fingers is an injury that has a dramatic presentation. The entire musculo-skeletal unit of the finger is intact, and the patient can often move the parts of his naked hand quite normally. The challenge for the reconstructive surgeon lies in resurfacing the hand or finger with a good quality pliable sensate skin cover while preserving the movements and function of the hand. Traditionally, skin grafting has been the standard method of reconstruction in such injuries. However, skin grafting does have many disadvantages, too. This article deals with the features of such injuries, management protocols and other reconstructive options available in the armamentarium of the hand surgeon.

INTRODUCTION

The avulsion of skin from the underlying structures is usually a result of trauma. Besides the possibility of injury to other structures, there may be a problem with viability of the skin involved. A degloving injury attains more significance in the hand because of the irreplaceable quality of the skin that has been lost, the exposure of the delicate structures in the hand,[1] the importance of providing an early cover to get back the function and the complexity of reconstruction. These injuries form a unique entity in hand surgery, which pose a challenge to the hand surgeon as far as reconstruction and rehabilitation are concerned.

CAUSE

These injuries occur when the hand is caught by a force and pulled at a low velocity. The force that holds the skin usually has some amount of irregular surface, that holds on to the skin and does not slip. When this then pulls in an outward direction — it may be the force moving outward, like the tyre of a vehicle that has run over the hand or it may be the counter force — the patient pulling his hand outward — for example, from a machine in which his hand has been caught. The most common causes are road traffic accidents, conveyor belt injuries and ring avulsion injuries.

In road traffic accidents, the usual mode of injury is the tyre of the vehicle running over the outstretched hand and forearm. As mentioned earlier, when this mechanism is the cause of a degloving injury, it is usually a low force — a two wheeler tyre moving fast over the hand; or a low velocity — a four wheeler tyre moving at a low speed. A higher speed usually results in injury to the underlying soft tissues and skeletal framework leading to fractures and muscle / tendon injuries.

In industrial accidents, there are two types of machines that can cause an outward force on the hand that has been caught in it — the conveyor belt and the roller machine. The roller machine usually does not get a hold on the skin, and hence, the force that pulls the hand out is not restricted to the skin, but pulls the entire upper limb outwards, and the entire load falls on the axillary region — the root of the limb. Hence the usual injury in such an accident is a brachial plexus injury. However, the conveyor belt machine has a rough surface, which can hold on to the skin of the hand and cause a degloving injury.

There is another common cause of degloving injury involving a single finger. When a person is wearing a ring and the hand is moving very fast in a particular direction, and the ring gets caught by a sudden stopping force, a ring avulsion injury occurs. The most common mode of such an occurrence is when a person is getting down from a bus, and his ring gets caught in some metallic projection on his way down. He is moving so fast, that when his ring gets caught, the force acting on the ring is equal to his body weight multiplied by the acceleration. This force is much too powerful and the ring degloves the entire finger.

PLANE OF SEPARATION

The plane of separation on the hand and forearm is typical in degloving injuries.

Forearm

Degloving on the forearm occurs at the subcutaneous level over the forearm. Hence, the deep fascia of the forearm remains intact and the muscle units are also intact.

Palm of the hand

Here too, the plane of separation is at the subcutaneous level. The deeper structure, which is the palmar fascia, and the retinacular system of the hand remain intact. This means that all the vital structures like the digital nerves and digital vessels are intact and well-protected, along with the flexor tendons and lumbrical muscles. Hence, there is usually no problem of compromised vascularity to the fingers, and the problem of gangrene of the distal fingers usually does not arise, as there are usually no injuries to the blood vessels at this level.

Dorsum of hand

When degloving occurs on the dorsum of the hand at the subcutaneous level, the extensor tendons get exposed, but there is no breach of the fascia covering the deeper muscles like the dorsal interossei. This implies that there is no motor deficit involving the interossei muscles, a common problem that occurs following other major injuries on the dorsum of the hand.

Fingers

The plane of separation of the degloved skin is at the subcutaneous level, leaving the flexor tendon sheath along with the neurovascular bundle totally intact on the volar aspect and the extensor tendon apparatus intact on the dorsal aspect. Hence, the movements of the finger are virtually unaffected.

PATHOLOGIAL ANATOMY

As the tissue loss consists of the skin and subcutaneous tissues only, sparing the retinacular system of the hand, there is no injury to the underlying neurovascular bundles, tendons or muscles. The only exception is ring avulsion injuries where degloving of the finger may be associated with amputation of the terminal phalangeal region. Hence, the common features running through all these injuries are:

Preservation of the musculoskeletal unit

Preservation of the vascularity of the remnant tissues

Preservation of the entire length of the finger / fingers / hand

Exposure of the underlying tendons, muscles, neurovascular bundles

CLASSIFICATION

Complete or partial

When the skin of the affected part has been totally removed, exposing the underlying structures, it is referred to as complete or anatomical degloving. Sometimes, the removal of the skin may not be complete and some portion of the skin may still be covering the underlying structures, although it has no anatomical attachment to the bed. This entity, called partial or physiological degloving is more significant, for three reasons:

This segment of skin that has been physiologically degloved may be non-viable, because it has lost all the blood supply from the bed.

This problem may not be recognised early, because on the surface, the skin appears to be intact.

Even if recognised, reconstruction may be delayed as the extent of damage may not be clearly assessed early.

CLASSIFICATION ACCORDING TO THE DEGLOVED PARTS OF THE HAND

Total hand

This type of degloving may be complete or partial.[2] It is not very common and the entire hand, fingers, palm, and dorsum are involved [Figure 1]. At the time of immediate examination, the patient will be able to show a complete range of active movements of the fingers and hand.

Figure 1

Degloving injury of the hand

Palm

This type of avulsion is usually partial degloving, [Figures 1–2] with attachment of the avulsed skin flap being on the ulnar border or the distal border of the palm. The skin is invariably non-viable, as the palmar skin has a rich blood supply on account of the perforators that run vertically in the numerous septae that anchor the palmar skin to the underlying skeletal structures. Although the arterial blood supply may be maintained by the subepidermal plexus, the venous drainage is inadequate.

Figure 2

Degloving injury of the palm

Dorsum

The skin on the dorsum of the hand usually does not get avulsed separately. This is because the skin on the dorsum is thin, and any force ruptures the skin and the force is borne by the underlying metacarpal bones.

Multiple fingers

Degloving can occur on multiple fingers at the same time. This injury usually involves the dorsum of the hand and sometimes the distal part of the palm.

Thumb

Degloving injuries of the thumb are quite common, owing to the unique position of the thumb as it stands out from the palm of the hand and is more vulnerable to shearing forces. Degloving of the skin of the thumb is very rarely associated with amputation at the tuft of the terminal phalangeal region. The nail plate is usually avulsed, but the nail bed may be retained on the stump.

Single finger

Each of the fingers can get degloved individually. The most common involvement is a distinct clinical entity called the ring avulsion injury, which usually involves the ring finger. Urbaniak has classified these injuries into three classes:

Class I: Circulation adequate

Class II: Circulation inadequate

Class III: Complete degloving or complete amputation

Forearm and arm

Degloving injuries can involve the entire forearm alone. This injury may be complete or partial.

EXAMINATION

The clinical examination of a patient with a degloving injury of the hand will consist of the following steps:

Examination of the general condition of the patient

Examination to rule out life-threatening injuries

Examination to rule out other major injuries

Examination of the involved hand and the degloved skin if available

Extent of the skin loss

Exposure / injury of vital structures

Available movements

INVESTIGATIONS

Baseline surgical investigations are conducted, as for any major surgery, with routine radiological films, clinical photographs and videographs showing the movements of the stump, which are mandatory.

DECISION-MAKING

Many factors play a role before a decision is made about the treatment protocol. The age of the patient, hand dominance and occupation of the patient are important considerations in reconstruction.

MANAGEMENT

Principles

Preserve as much of the structures as possible

Early primary definitive skin cover

Good quality skin cover

Early return of function

Possibility of conducting any secondary procedures

Unique aspects

The musculoskeletal unit is usually intact

The requirement of skin is large in some cases

Three-dimensional defect, especially when multiple fingers are involved

SURGICAL OPTIONS

Replant — Revascularise

The first and best surgical option of treatment in such cases is always replantation[3] or revascularisation. When the degloved skin is totally removed from the body, it can be put back by a surgical procedure called replantation.

When the skin has been physiologically degloved, but is still attached to the body, it can be vascularised by either arterial anastomosis, venous anastomosis or both, as the situation warrants, and this procedure is called revascularisation[45] [Figure 3]. Thus, replacing the degloved part and vascularising it by microvascular anastomosis gives back the patient skin and a soft tissue cover in good quality and quantity.[34] Replantation of degloved parts [Figure 4] has got certain unique features

Figure 3

Replantation

Figure 4

Revascularisation

There is usually an avulsion of the blood vessels also, and hence, the intimal injury may extend beyond the visible level of injury of the vessel

Debridement of the avulsed vessels is of utmost importance before embarking on microanastomosis

The technique of crossed arterial anastomosis may be used when the digital arteries to the finger are cut at different levels [Figure 5]

Figure 5

Technique of crossed arterial anastomosis

The use of prudent vein grafts, either for arterial repair or venous repair will go a long way in giving a successful outcome.

In the case of the degloved finger, it is not enough to vascularise it, but it must be ensured that the nerve supply and sensation is also restored by using the technique of microneural repair of the cut digital nerves.

However, this option may not be possible in all the patients for the following reasons:

The degloved skin may have been crushed, or the vascular pedicle of the skin may be unsalvageable

There may be other life-threatening injuries, which may preclude any major surgery on the hand in the emergency situation

There may be concomitant comorbid conditions like extremes of age, cardiac disease, or uncontrolled diabetes, where prolonged anaesthesia may be detrimental.

When replantation or revascularisation is not possible, it may sometimes be possible to use the degloved skin as a full thickness graft or just thick split skin graft [Figure 6]. The skin is defatted and draped over the degloved hand / finger. This will be wobbly; hence, it needs to maintain good contact with the bed to ensure a graft-take. To achieve this, a negative pressure in the form of suction is used under the graft and a positive pressure is applied with a bulky dressing and compression.This procedure may be attempted when there is no structural damage to the degloved skin. When this is not possible, the next option is to decide whether to retain the hand / finger, or amputate it.

Figure 6

Skin grafted hand and fingers

AMPUTATION VERSUS SALVAGE

In a majority of the cases, the decision should be made to preserve the degloved part and reconstruct it. However, there are some situations where amputation can be offered as a treatment option.

Degloving injury on a marginal finger [Figure 7]— the index finger or little finger: Very elderly age group, manual labourers who cannot afford the time required for the reconstruction process, who are the sole working members of the family, can be offered amputation, if the index finger or little finger is involved. The functional and cosmetic deficit following the removal of these fingers is minimal, and rehabilitation is quicker following amputation.

Figure 7

Amputation of marginal finger

Amputation may also be advised for patients who have had a degloving injury of a marginal finger and will not be able to attend physiotherapy regularly, and those who do not agree for the multiple procedures that may be required, like flap thinning and tenolysis.

When the entire hand and all the fingers have been degloved, it may be prudent to amputate the fingers at the level of the distal interphalangeal joint, as it reduces the amount of skin required and at the same time does not overtly compromise the function of the hand.

TYPES OF RECONSTRUCTION

The next major decision to be taken is the method of surgical reconstruction.

The aims of surgical reconstruction are:

To provide thin, pliable and sensate skin that prevents contracture and stiffness

To allow the reconstructed tissue to heal quickly, to allow early mobilisation

To provide skin durable enough to withstand a secondary surgical procedure

To create a result that is cosmetically acceptable

Having these aims in mind, we have two choices – skin graft [Figure 7] or flap. Each of these has certain advantages and disadvantages when used in the reconstruction of degloving injuries on the hand [Table 1].

Table 1

Use of skin graft in hand reconstruction

From the earlier discussion it may be obvious that although skin flaps have some problems [Table 2], they offer much better reconstruction than skin grafts. The next decision to be made is the choice of the skin flap.

Table 2

Use of skin flap in hand reconstruction

CHOICE OF SKIN FLAP

The standard flaps used in the reconstruction for degloved fingers are the groin flap, the abdominal flap, the bilobed flap, the quadrant flap, the abdominal pocketing procedure and free vascularised flaps.

Groin flap

This pedicled skin flap is based on the superficial circumflex iliac artery. It provides thin, compliant skin for the thumb, single finger [Figure 8] and double finger defects. This flap has the advantage of primary donor site closure, hidden donor site, vascular reliability and versatile use.

Figure 8

Groin flap for single finger reconstruction

Abdominal flap

This flap is a time-tested flap that is used for resurfacing degloving injuries of the palm or dorsum of the hand. It has the advantages of ease of elevation, ease of positioning and vascular reliability.

Bilobed flap

When the defect involves both the palm and dorsum of the hand, the groin flap or the abdominal flap cannot individually resurface the defects, but when combined together in the form of a bilobed` flap, they will provide adequate skin cover and a good reconstruction option.

Quadrant flap

Degloving injuries involving all the fingers and part of the palm and dorsum of the hand require more skin than that provided by a bilobed flap. This is possible by the quadrant flap [Figure 9], which utilises all the skin available in the lower outer quadrant of the abdominal wall combined with the groin area. The advantage of this flap is the ease of elevation, vascular reliability of the flap and versatile positioning due to a narrow skin pedicle.

Figure 9

Quadrant flap in reconstruction

ABDOMINAL POCKETING PROCEDURE

When the entire hand has been degloved, the flaps described earlier are not adequate. More amount of skin is required. In such situations, the abdominal pocketing procedure is useful [Figure 10]. It consists of burying the degloved hand in a subcutaneous abdominal pocket.

Figure 10

Abdominal pocketing method of reconstruction

The skin brought on to the hand by this technique may be used in different ways.

After a period of two weeks and a delay, the flap may be divided. This provides good quality skin on the dorsum of the hand, and the volar side may be skin grafted.[8] If necessary, this grafted skin on the volar side can be excised and resurfaced with another abdominal flap from the remaining area.

After a series of delay procedures, it is possible to raise the adjoining abdominal skin during the step of flap division. This will provide skin to cover the volar side too. However, this will provide a bulky loose skin on the palm, which may hamper movements and function.

After a period of two weeks, the hand is removed from the abdominal pocket along with only the soft tissues that cover it. The entire raw area on the hand can now be skin grafted, by the ‘crane principle’. By this procedure, the abdominal skin is not sacrificed. This provides soft pliable skin for the entire hand, but it cannot withstand any further surgical procedures.

FREE TISSUE TRANSFER

All the procedures described earlier are staged procedures. If a single stage cover has to be provided, free tissue transfer by the microvascular technique[9] may be done. The tissue that is transferred may be either an anterolateral thigh flap,[10] which is a skin flap, or a latissimus dorsi muscle flap,[11] which is covered with a skin graft. The disadvantage of these procedures is the paucity of tissues that can be transferred by this method, and the need for expertise in microvascular surgery, to carry out the procedure.

THUMB RECONSTRUCTION

The importance of reconstruction of the thumb cannot be over stressed. The thumb contributes to about 40 % of the total work done by the hand and it has certain characteristics that are needed for it to function optimally.

Length

Stability

Mobility

Sensation

Cosmesis

In a degloved thumb, there is no deficit in the length, stability or movements, but emphasis must be placed on the remaining three criteria of:

Good quality skin cover in the form of glabrous skin

Sensate skin on the contact areas

Cosmetically acceptable reconstruction including a nail complex

Reconstruction options for a degloved thumb

Microsurgical option of a wrap-around flap[12] from the great toe, if the degloving is restricted to the level distal to the metacarpophalangeal joint.

Classical osteoplastic reconstruction with a tubed groin flap [Figure 11] and a sensate neurovascular island flap to provide sensation. If the nail bed is intact, it can be protected with a skin graft laid with the epithelial side over the nail bed. When the groin flap is detached, the nail bed is totally intact and not scarred. The Littler's flap to provide sensation should be provided at a later stage.

Figure 11

Thumb reconstruction by the osteoplastic method

PRESURGICAL COUNSELLING

Having taken a decision, it is important to convey and communicate with the patient about the following.

The procedure that is planned

A detailed description of where the skin will be taken from and how that area will be covered. The possible complications that can occur and how they will be managed must also be discussed

The scars that will be present on the hand and the other areas of the body from where the skin will be harvested

The anaesthesia that will be required and the possible complications that may occur

The total period of hospital stay

The approximate time of total reconstruction and when he can get back home and when he can get back to work.

The importance of therapy, and the need for splints, mobilisation, scar massage and compression

What amount of function can be expected at the end of reconstruction

The need for multiple secondary procedures to complete the reconstruction process

SECONDARY PROCEDURES

After reconstruction in a degloved hand or finger, certain secondary procedures may be required.

Scar revision

During the process of flap coverage, there may have been areas of less than optimal healing, and these areas tend to cause contracted scars or hypertrophic scars. These scars need to be removed both for function and cosmesis.

Flap thinning

The flap that is provided is invariably bulky and requires to be thinned. The thinned flap will also be cosmetically and functionally more acceptable.

Syndactyly release procedure

When multiple fingers have been involved, it is not possible to individually cover each finger with a flap. A single flap is utilised, and hence all the fingers are together inside the flap. They have to be released and separated to get back their individuality and function.

ROLE OF HAND THERAPY

In no other hand injury is the role of hand therapy more important. The clinical entity of degloving injury means that the skin has been lost, but the musculoskeletal unit is intact, and hence, the movements of the part have been preserved. However, during the process of reconstruction of the skin, scarring and stiffness reduce these movements. The physiatrist plays a role in the following aspects.

Evaluating the hand and its movements

Scar massage, which may be mechanical massage or with ultrasound, to soften the scars that have formed

Compression garments to support the reconstruction and also to make the scars soft and supple

Active and passive mobilisation of the fingers and hand[3]

Appropriate splinting to avoid contractures. Straightening splints to the fingers, thumb web spacer splints — static or dynamic, finger web spacers, knuckle bender splits may be appropriate in such patients

Occupational assessment to determine what the reconstructed hand is capable of doing

Rehabilitating the patient back to the society as a useful and productive member. The patient may not be fit to carry out the work that he had been doing before the injury. Hence, he must be accommodated back with a job that fits the occupational capabilities of the hand post reconstruction.

Degloving injuries are unfortunate accidents, where protective integument of the hand or finger is lost. The priorities in such patients are early reconstruction and rehabilitation. Reconstruction in degloving injuries is one of the most exciting adventures that the hand surgeon can embark on. Success in such a complex problem lies in diligently following every single principle in the armamentarium of hand surgery