Fingertip Injuries

Introduction

The hand is in harm’s way. It is at the frontier of all work and contact with the environment. The fingertips, as a collective functional unit, bear the statistical brunt of such injuries. Hand injuries constitute the single most frequent surgical presentation in an average Emergency Department.

The hand is unique in its dual role as a considerable gatherer of information about the environment and also as an executor. Unlike the other major sensory organ, the eye, the hand is also able to act on the information gathered, constantly modifying action by feedback of sensation and proprioception. The gathering of information about the environment is especially developed in pulp and palmar digital skin, which is not to be regarded merely as skin covering, but as a specialized organ in its own right. The dense population of sensory end organs is housed in skin with specialized, mechanical properties. The skin is robust and yet deformable – the nail complex and the skeleton provide a fixed stop, against which the pulp and palmar skin complex are deformed – without such a rigid stop, one would obtain less meaningful information about the contour and texture of a held object or touched surface.

The esthetic importance of the hand is not to be underestimated and is an important consideration in all reconstruction. Irrespective of custom and attire, in virtually all societies, the hand is always on display (the hand is exposed even in societies where the face is concealed). The back of the hand, in particular, is a significant esthetic unit. In this regard, function and appearance are closely interlinked. The hand which behaves fluently and efficiently attracts little attention, even if it carries significant scar, or is missing anatomical parts. Smooth, healthy-looking skin cover, as well as fluid, natural behavior, form important aspects of social acceptability. Hand gestures reinforce facial expression and in some spheres, hand movement and posture constitute a very specific vocabulary, interpretable by those who converse in that language. Aside from the obvious example of signing for the deaf, the orchestra conductor’s hand gestures speak a clear language to musicians and culture-specific hand gestures convey meaning over distance beyond that possible through sound. Convention and social context convey specific messages with hand gestures – the extended index finger held vertically over the lips is universally interpreted as a request for quiet, for silence. It is also relevant that the hand is the most frequent acceptable point of contact; in most societies, the handshake is considered a permissible intrusion into personal space, and a permitted form of contact, irrespective of the difference in social standing of those shaking hands.

The hand is an integral part of one’s identity for any individual but specific professions imbue the hand with an additional importance. The musician, for instance, has a special relationship with the hand since this forms an integral part of his/her identity and “voice.” The same can be said of the craftsman or in sports that use the hand. Although these aspects form an important element of management, one must not overrate the contribution of profession to the decision-making process. While some methods of reconstruction may entail an unacceptable period off work for, say, the manual worker, whose main concern may be for strength and durability, all will require a large measure of pain-free, sensate dexterity. Irrespective of work or leisure pursuits, all will still need to perform delicate, precise tasks, such as writing and doing up fastenings and buttons, touching spouse and offspring. Most will be disturbed by an unattractive extremity on display.

Since the hand is the part most frequently involved in work-related injuries, the issue of personal injury claims and the cloud of possible compensation frequently hangs over the outcome of repair and reconstruction.

The growing hand presents special challenges on a number of fronts. Any repair must take into account the facilitation of growth of soft tissues and skeletal elements. Scarring and contracture, a perennial problem in the hand, assume an added importance. To these factors must be added the factor of parental anxiety and elements of guilt and regret centered on the occurrence of the injury in the first place. In general, the management of the child’s hand involves the management of the family.

These various factors should all figure in the assessment of injury, the “feel” of patient compliance and cooperation, the choice and planning of repair and reconstruction, and the required aftercare. All too often these injuries are downgraded in the queue of surgical priorities – many still consider that “all soft tissue injuries of the pulp heal” without regard to the quality of function of such healing. Injuries that can lead directly to significant loss of function, persistent pain, and compromised appearance are still, regrettably, considered trivial and meriting little surgical input. They are often misguidedly delegated to inexperienced members of the surgical team with little appreciation of their complexity and functional significance.

Assessment

The challenge of reconstruction in the hand lies in the assessment and decision-making, not in the technique, however immaculately executed is the latter. In assessing any injury (and the patient) one brings to bear experience and a big repertoire so that, as far as possible, questions are answered before the start of surgery. This is not to say that plans may not change when the examination reveals more detail, but it is the planning and selection of technique that is the focus and the essential to a good outcome.

In the field of reconstruction, there are no recipes, only principles. In the management of reconstruction challenges of the digits, one vital principle is the appreciation that not all areas of the hand are of equal functional value.

Observation of the hand in action soon reveals that all digits have leading and trailing aspects. While one would not suggest that any part of the hand is of lesser importance, in reconstructive terms these could also be considered “high premium” and “low premium” territories ( Fig. 46.1 ).

The leading edge is the more commonly used in contact with a held object or contact with a surface. The trailing edge is less often in contact, and tends to have less developed discriminatory abilities or needs. This principle is most true of the thumb: the ulnar pulp “leads” and is involved in virtually all dexterous activity and certainly all precision actions, since it is this area which faces the long digits most effectively. By contrast, the radial pulp “trails” during most tasks coming into play with relatively unspecialized tasks such as tapping on a horizontal surface or keyboard. The principle is least true of the index, both of whose aspects are frequently involved in common activity.

Once this principle is accepted, one can start to assess the functional significance of a specific defect and the availability of suitable methods of reconstruction:

• 1.

  High premium areas require the best possible reconstruction, preferably sensate, glabrous pulp skin taken if possible from the same digit.

• 2.

  Injury to a low premium area may be reconstructed acceptably and reliably with relatively nonspecialized cover, such as a skin graft or an insensate skin flap.

• 3.

  Low premium areas can be considered for transfer to high premium areas, preferably on the same digit, as for instance the reconstruction of ulnar pulp in the thumb using radial pulp ( Fig. 46.2 ).

  

These observations are proposed as factors to be taken into account, and are certainly not absolute. They are amongst many that should be considered, including the requirements of the patient overall, likelihood of compliance, as well as special requirements for a particular patient, such as the playing of musical instruments or professional sport.

In few other areas of reconstruction is collaboration with the patient as essential. This element needs careful assessment if one is to obtain a good outcome – in this situation a good outcome is the maximum restoration of function (and hence appearance) and an acceptance by the patient of any limitations consequent on the injury.

Detailed informed consent also needs to take into account the time and effort investment required of the patient, particularly in the more complex reconstructions. The extension of the site of injury and/or the involvement of distant donor sites are all factors to be included in the detail of the process of informed consent.

Finally, in the process of assessment, the surgeon must also have a realistic and honest assessment of his/her capabilities. Many methods of reconstruction are attractive to the surgeon since they fulfill a natural mechanical neatness and challenge of construct. The seduction of such methods must be resisted in the absence of expertise or adequate guidance (and, preferably, also assistance) by those more experienced.

It cannot be overemphasized that the method selected must suit the defect and the level of expertise of the surgeon. In this regard one must mention that it may be entirely appropriate to select a temporary method known to be insufficient for long-term wear and restoration of function (such as a dressing or a split-skin graft on pulp), leaving all options open for reconstruction with the availability of appropriate expertise. If this approach is selected, it is wise to present this to the patient as a two-stage procedure so that he/she is prepared for the second surgery and it does not come as a “salvage,” or adjustment, of the first.

Healing by Secondary Intention

Both pulp and palmar skin have remarkable powers of regeneration, as evidenced by the reliable healing of the open palm technique advocated by McCash.

Large defects of pulp will heal reliably provided a number of important criteria are observed:

• 1.

  The defect must be suited to this method. No vital structure, such as tendon, bone, or joint, must be exposed. Severely contaminated or crush defects must be thoroughly debrided of all contamination or necrosis.

• 2.

  The hand must be elevated.

• 3.

  The patient must understand that the method requires careful adherence to instruction and compliance with treatment. (Many patients will only remember that “It needs no surgery” and this is rapidly translated into “It needs no care”).

• 4.

  Nonadherent dressings require regular change, preferably on alternate days. Exception is made for children, where it is routine to leave a dressing undisturbed for a week, after which the wound can be left exposed, in order to avoid the trauma of painful dressings.

The dressing in direct contact with the wound is a matter of personal preference. Tulle gras (paraffin impregnated gauze) is traditional. It is cheap and easily available or can be improvised, but dries rapidly and tends to adhere more than one might expect. Many, superior, alternatives are available, such as thin, perforated silicone sheeting (e.g., Mepitel, Mölnlycke Healthcare, Gothenburg, Sweden), which is resistant to all adherence. Chitin (Beschitin, Unitika, Osaka, Japan), and other natural substances, have their advocates. The important aspects are: nonadherence, a barrier to contamination, and assiduous care and compliance.

Surgical Options for Cover

Amputation

In cases where a significant part of the digit is crushed with accompanying disruption of the nail complex and/or the distal interphalangeal joint, amputation with closure of locally available skin may be the indicated option. In this situation, it may be appropriate to elect to ablate any nail elements which, regenerating, will be unsupported, nonadherent, unattractive or likely to lead to functional problems such as snagging on clothing.

Much morbidity results from amputation performed without proper regard to indications and points of technique. There is a natural tendency to preserve length at all costs. The aim should be to achieve a nontender digit covered by good-quality skin, irrespective of length. It is better to elect for a slightly shorter length, with good quality, mobile skin cover, than to preserve length at all costs but with a tight and painful digit end. A digit with tense, painful, skin cover may well be excluded from function, resulting in an effective loss of all useful length. This is particularly true of the index, which is readily substituted by the middle finger and regularly requires subsequent revision. It is a wise surgeon who seeks to prevent the cycle of pain, tenderness, and exclusion.

There are three generally indicative levels of amputation of the fingertip ( Fig. 46.3 ):

• Level 1: involves loss of skin and only a minimal loss of nail and distal phalanx. In this case all of the tip vital structures are preserved and skin cover is indicated.

• Level 2: involves loss of skin and most of the distal phalanx/nail complex. In this case the nail should be ablated and the next proximal structures to preserve are the tendon insertions. Just enough bone should be left, to preserve these insertions which will preserve power and elements of proprioception.

• Level 3: has lost all nail elements and the tendon insertions. The condyles of the middle phalanx can be removed to prevent an unattractive, spatulate stump shape. The phalanx is shortened to a level where tension-free, good skin cover can be achieved. One should not be tempted to anchor the tendons, or to suture them to each other. This invariably leads to an imbalance and most frequently to a flexion contracture.

All amputations require attention to the nerve ends. One should take the opportunity of any skeletal shortening to keep the nerve ends long and to transpose them dorsally, away from contact areas.

Options for Skin Cover

If skin cover is required the options are:

• 1.

  Skin graft, or

• 2.

  Flap cover.

Reconstruction most often involves moving tissue around from one site to another, with the added, vital, phrase “and keeping it alive.” Blood supply is paramount. A skin graft requires a bed capable of angiogensis, the essential process of “take.” “Take” is the establishment of a blood supply to support a graft. A flap requires no such bed – it brings its own blood supply and can be placed over any surface, including metalwork. Provided this principle is observed, the decision can then be taken on what form of cover will best restore function and structure. The concept of the “reconstructive ladder” with its implications that one chooses the simplest reconstruction available, is outdated – one chooses what is appropriate and best restores form and function.

It follows that the surgeon must have in his/her repertoire as large a variety of reconstruction as possible, in order to match the reconstruction to the defect, and patient, and not the other way around. This, incidentally, is another strong reason for involvement of experienced, senior surgeons. All too often this process is left to those with one or two methods at their disposal; this invariably results in the dispensation of a method which the surgeon knows, rather than that which is appropriate.

Flaps with Less than Pulp-Quality Sensation

The Kite Flap

This flap was originally designed, with a wide base pedicle, by Holevitch. Vilain and Michon developed this design, narrowing the pedicle to about 1 cm, including the vascular axis, and this design was named the “flag flap.” It was Foucher who islanded the skin flap, denuding the pedicle of skin and conferring a greater degree of mobility as well as the potential for tunneling of the pedicle. The island of skin is raised in a plane just superficial to the extensor tendon parateneon (which must be left intact so as to receive a graft). The pedicle includes the first dorsal metacarpal artery, local veins, as may be found (usually plentiful), and any superficial branches of the radial nerve that are identifiable ( Fig. 46.4 ).

The radial nerve branches provide sensation but the density of end organs in the dorsal skin never matches the density required to provide pulp-quality sensation and it is for this reason that this flap is included in the “insensate” category.

Although it is tempting to use it for resurfacing of the leading edge of thumb pulp, its use should be reserved to areas with less demanding sensory qualities, such as the dorsum of the thumb and the radial aspect.

Important Points of Technique

• 1.

  The first dorsal metacarpal artery should be identified early since it may follow a course part way through the substance or fascia of the first dorsal interosseous muscle.

• 2.

  It is prudent to include any veins that can be gathered into the pedicle – a surfeit of veins makes for a healthier flap.

• 3.

  Terminal branches of the radial cutaneous nerve are fine and must be sought and preserved.

• 4.

  If the flap is tunneled, the tunnel must be generous and without sharp kinks in its course.

• 5.

  The donor area must be carefully protected, the paratenon left intact so as to receive a graft.

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