Acknowledgments:
The author wishes to recognize the work of previous authors Dr. William Kleinman, Dr. James Strickland, Dr. Neil Salyapongse, and W. P. Andrew Lee for their contributions to Green’s Operative Hand Surgery and this chapter.
The hand without a thumb is at worst nothing but an animated fish-slice, and at best a pair of forceps whose points don’t meet properly. —John Napier
Despite a long-standing recognition of the uniquely human way of using the hand, anthropologists have only recently defined the significance of the structure of the human hand that allows us to forgo an arboreal lifestyle in pursuit of vocations ranging from computer programmer to auto mechanic to surgeon. Their findings focus in large part on the anatomic features allowing three “grips” that differentiate the human hand from that of other hominids. These grips—the pad to side, three-jawed chuck, and five-jawed cradle-chuck—are possible due to the structure of the human thumb. As described by Napier, the absence of the thumb, whether due to failure of formation or loss from trauma, significantly impairs hand function. In previous editions of this textbook, Drs. Kleinman and Strickland provided an excellent summary of 125 years of efforts by hand surgeons to preserve and, if necessary, reconstruct thumb function. As they predicted, many of these creative techniques have given way to the demonstrated success of microsurgery, including improved initial thumb salvage via replantation and reconstruction using free toe transfer. Unchanged from their writings is the dictum that, for a willing and motivated patient, “reconstruction of an opposable thumb should be attempted whenever possible by using whatever technical pathways are available to the surgeon.”
With a few notable exceptions, techniques used to reconstruct the thumb after trauma are not unique to this digit. Skin grafts, local or regional flaps, free tissue transfer, and distraction and lengthening are all discussed at length in their respective chapters. A brief review of the evolution of thumb reconstruction outside of microsurgical techniques is provided to give the reader some perspective on the breadth of procedures developed. After this, we place the available procedures within a framework to help guide the clinician when planning thumb reconstruction. Apart from advances in microsurgery and refinements in toe transfer techniques, few changes in the procedures used for thumb salvage and reconstruction have taken place. Given this, we describe procedures unique to thumb reconstruction in detail, with attention to both preoperative planning and postoperative care.
Historical Review
Although technical advances have led to changes in surgical methods, the general surgical philosophies of thumb reconstruction have remained relatively constant since their inception. In the latter part of the 19th and early 20th centuries, two distinct surgical philosophies evolved: (1) optimization of remaining function via local thumb phalangization after partial amputation, essentially a deepening of the first web space, as first described by Huguier ; and (2) distant pedicle flap attachment with delayed secondary detachment, first described in 1897 by Nicoladoni. The principle of phalangization continued to evolve throughout the 20th century as techniques such as the “Z”-plasty, four-flap “Z”-plasty, dorsal rotational flap, and metacarpal lengthening were used to provide additional web span and depth. Nicoladoni’s staged great toe–to–thumb transfer and the delayed pedicle finger transfers of Luksch are clearly mirrored in our current microvascular toe-to-thumb and occasional finger-to-thumb transfers.
Also during the late 19th century, the groundwork for the development of the neurovascular island flap was laid. In addition to its role in plastic surgery and craniofacial reconstruction, this work would become the basis for the third persistent theme in thumb reconstruction: Gosset’s revolutionary concept of transfer of a digit on its own neurovascular pedicle. In introducing this technique, Gosset not only revolutionized contemporary traumatic thumb reconstruction but also pioneered the seminal principles of reconstruction for a congenitally absent thumb. His initial recommendations involved simple lateral displacement of the index ray without bone shortening. Subsequently modified to include metacarpal recession and rotation, intrinsic muscle transfers, and skin flaps specially designed to produce a wide first web space free of scar, pollicization via nonmicrovascular transfer of the long, ring, and little fingers remains one of the mainstays of thumb reconstruction.
The fourth pathway to thumb reconstruction consisted of osteoplastic thumb creation. Used extensively before World War II, osteoplastic reconstruction was performed in either one or two stages. The first step involved attaching the injured thumb stump to a random tubed pedicle of vascularized skin and subcutaneous tissue from the abdomen or groin; an iliac crest corticocancellous bone graft could be inserted and fixed to the residual thumb either at a second stage (division of the tubed pedicle) or during primary formation of the pedicle. As recently as 1955, advances in osteoplastic thumb reconstruction were reported, with Moberg’s introduction of the “island pedicle” transfer of vascularized, sensible cornified skin from an uninjured portion of the hand to restore stereognosis to the tactile portion of the osteoplastic thumb. This technique has been widely practiced and remains a fundamental approach in complex thumb reconstruction after trauma.
General Considerations
An ideal reconstruction of the thumb would replace “like with like,” restoring both function and appearance. Replantation has demonstrated great success, in that it restores the actual lost thumb and often yields excellent functional outcomes. When replantation is not possible or fails, the surgeon must re-create the likeness of the thumb. Deconstructing the ideal thumb function into its basic elements can assist the surgeon in choosing a reconstructive technique to provide an optimal outcome. Although authors differ in the specific breakdown of thumb requirements, two broad categories must be addressed: sensation and opposition. Sensation can be further divided into freedom from pain and adequate sensibility to interact with, or at least protect itself from, the environment. Opposition, the hallmark of “thumbness,” necessitates length, stability, strength, and mobility. The exact importance of each of these factors varies, depending on the individual needs of the patient: a jeweler who seeks sensibility and mobility may require different management than a manual laborer who may sacrifice mobility for stability and power.
For a patient to consistently use a reconstructed thumb, it must have painless stable skin coverage, be durable enough for normal use, and have at least protective, if not normal, sensation. Thus, regardless of the level of amputation and planned thumb length after salvage or reconstruction, every attempt should be made to restore at least an acceptable level of sensory cognition. Procedures should be selected to provide a predictably satisfactory level of tactile perception and stereognosis. Failure to achieve this quality was the most consistent reason for patients’ thumb disuse after many early reconstructive techniques (despite the fact that other functional requirements may have been met by the procedures). The use of neurovascular island pedicle techniques, sensory-innervated cross-finger flaps, and other methods of transferring innervated skin have greatly enhanced the ability to restore sensation when carrying out thumb salvage after trauma or to address congenital disorders.
First among the components of opposition is length; amputations that deprive the thumb of the distal phalanx or occur just proximal to the interphalangeal (IP) joint may not require reconstruction. Loss at or more proximal to the shaft of the proximal phalanx, however, usually leaves a stump inadequate for pinch and grasp functions. To oppose the remaining digits, a thumb of sufficient length must be antiposed (abducted, slightly extended, and pronated). Whereas thumb IP flexion results in slight pronation of the distal phalanx, normal motion at the metacarpophalangeal (MP) or IP joints is not mandatory. In contrast, active thumb function depends on preserving a full arc of circumduction at the carpometacarpal (CMC) joint. If a substantial range of CMC motion cannot be attained, an essentially sensate prosthesis may be created by arthrodesing the thumb in nearly full abduction-opposition (40 degrees of abduction, 15 degrees of extension, 120 degrees of metacarpal pronation), so that other mobile digits can be flexed to meet it. Thus, strength and mobility that more closely approximate normal thumb opposition may be sacrificed to provide a stable, if immobile, post for resistance during pinch and grasp.
Additional considerations when counseling a patient on the options for thumb reconstruction include the patient’s age, sex, occupational demands, hand dominance, and subjective needs. Once the patient has expressed an interest in a restorative or reconstructive effort, an open and honest dialogue between the patient (and/or family) and surgeon is necessary before any final decision can be made. Rehabilitation after any reconstructive procedure is critical to obtaining a successful outcome; the patient must be motivated and should fully understand that his or her efforts during therapy will be as important as the surgery (if not more so) in regaining a functional thumb.
General Considerations
An ideal reconstruction of the thumb would replace “like with like,” restoring both function and appearance. Replantation has demonstrated great success, in that it restores the actual lost thumb and often yields excellent functional outcomes. When replantation is not possible or fails, the surgeon must re-create the likeness of the thumb. Deconstructing the ideal thumb function into its basic elements can assist the surgeon in choosing a reconstructive technique to provide an optimal outcome. Although authors differ in the specific breakdown of thumb requirements, two broad categories must be addressed: sensation and opposition. Sensation can be further divided into freedom from pain and adequate sensibility to interact with, or at least protect itself from, the environment. Opposition, the hallmark of “thumbness,” necessitates length, stability, strength, and mobility. The exact importance of each of these factors varies, depending on the individual needs of the patient: a jeweler who seeks sensibility and mobility may require different management than a manual laborer who may sacrifice mobility for stability and power.
For a patient to consistently use a reconstructed thumb, it must have painless stable skin coverage, be durable enough for normal use, and have at least protective, if not normal, sensation. Thus, regardless of the level of amputation and planned thumb length after salvage or reconstruction, every attempt should be made to restore at least an acceptable level of sensory cognition. Procedures should be selected to provide a predictably satisfactory level of tactile perception and stereognosis. Failure to achieve this quality was the most consistent reason for patients’ thumb disuse after many early reconstructive techniques (despite the fact that other functional requirements may have been met by the procedures). The use of neurovascular island pedicle techniques, sensory-innervated cross-finger flaps, and other methods of transferring innervated skin have greatly enhanced the ability to restore sensation when carrying out thumb salvage after trauma or to address congenital disorders.
First among the components of opposition is length; amputations that deprive the thumb of the distal phalanx or occur just proximal to the interphalangeal (IP) joint may not require reconstruction. Loss at or more proximal to the shaft of the proximal phalanx, however, usually leaves a stump inadequate for pinch and grasp functions. To oppose the remaining digits, a thumb of sufficient length must be antiposed (abducted, slightly extended, and pronated). Whereas thumb IP flexion results in slight pronation of the distal phalanx, normal motion at the metacarpophalangeal (MP) or IP joints is not mandatory. In contrast, active thumb function depends on preserving a full arc of circumduction at the carpometacarpal (CMC) joint. If a substantial range of CMC motion cannot be attained, an essentially sensate prosthesis may be created by arthrodesing the thumb in nearly full abduction-opposition (40 degrees of abduction, 15 degrees of extension, 120 degrees of metacarpal pronation), so that other mobile digits can be flexed to meet it. Thus, strength and mobility that more closely approximate normal thumb opposition may be sacrificed to provide a stable, if immobile, post for resistance during pinch and grasp.
Additional considerations when counseling a patient on the options for thumb reconstruction include the patient’s age, sex, occupational demands, hand dominance, and subjective needs. Once the patient has expressed an interest in a restorative or reconstructive effort, an open and honest dialogue between the patient (and/or family) and surgeon is necessary before any final decision can be made. Rehabilitation after any reconstructive procedure is critical to obtaining a successful outcome; the patient must be motivated and should fully understand that his or her efforts during therapy will be as important as the surgery (if not more so) in regaining a functional thumb.
Thumb Reconstruction after Partial or Complete Traumatic Loss
Thumb function after amputation depends primarily on the remaining elements. Consequently, most algorithms for thumb reconstruction begin by stratifying the injury by level of loss. * Division of the thumb into functional levels varies slightly from one author to the next ; however, when approaching the reconstructive needs of the thumb, we prefer to stratify thumb defects after the style of Lister, as follows :
* See references .
- 1.
Acceptable length with poor soft tissue coverage. These injuries are typically tip or pulp amputations that leave adequate length, functional thenar musculature, and basal joint mobility for opposition. Additional requirements for these injuries focus on sensibility or sensitivity and durability of skin coverage.
- 2.
Subtotal amputation with questionable remaining length. This group encompasses the widest range of needs, from injuries requiring only soft tissue coverage to those demanding reconstruction analogous to total amputations. Choice of procedure is determined chiefly by the patient’s perceived needs.
- 3.
Total amputation with preservation of the basal joint. Although intrinsic thumb function is lost to varying degrees, the foremost requirement of amputations at this level is restoration of length. The extent of remaining intrinsic function, as well as the chosen reconstructive technique, determines how the new thumb is motored.
- 4.
Total amputation with loss of the basal joint. Provision of length is critical, but functional opposition becomes more difficult. Either a substitute for the basal joint must be provided in the reconstruction, or the thumb must be arthrodesed in antiposition.
The following sections present our rationale for this division, define the differing reconstructive needs at each of these levels, and describe in detail the surgical options available.
Acceptable Length With Poor Soft Tissue Coverage
Even complete amputation of the thumb at the level of the IP joint, when treated with appropriate revision amputation, rarely results in significant functional deficit. Therefore, this level has been described as the “compensated amputation zone.” If the skeletal and soft tissues have suffered damage sufficient to make restoration of a stable, sensate thumb tip unlikely, completion amputation and closure may provide a more immediate and equally functional outcome. In this setting, it is important that closure be carried out using sound amputation principles, including avoidance of boxy stump edges and proximal resection of the digital nerves. If these techniques are properly carried out, a good stump in the distal third of the thumb can function well with almost no functional disability.
A broad spectrum of injury exists short of complete amputation or unsalvageable trauma to the distal thumb. Goals of treatment include restoration of skeletal stability; coverage of the thumb with durable, painless skin; and restoration of adequate sensory perception. The specific procedures used to accomplish these goals vary, depending on the amount and depth of tissue loss. An attempt should be made to salvage all viable tissues consistent with these objectives. Although injuries to the palmar pad of the distal phalanx of the thumb can be managed by the same coverage techniques applicable to fingertip injuries, the approach may be somewhat different as one strives to preserve length.
The choice of reconstructive procedure for soft tissue deficits over the distal thumb depends primarily on the size of the defect. When the loss of skin and subcutaneous tissue from the terminal aspect of the distal phalanx is small (typically <1 cm 2 ) and no exposed bone is present, reasonable treatment options include allowing spontaneous healing by secondary intention, free skin grafts, lateral triangular advancement flaps, “V-Y” advancement flaps ( Figure 48.1 ), and a variety of other techniques. For these small defects, we prefer conservative, open treatment to allow the wound to heal through secondary intention. The advantage of spontaneous healing is more favorable wound contraction, which results in a minimal defect with nearly normal sensation preserved. At the time of presentation, patients undergoing conservative treatment should have the wound cleansed and covered with a nonadherent dressing. The initial dressing is removed at 24 to 48 hours, and daily dressing changes are performed thereafter until the wound has completely closed. Patients should be counseled that a few weeks may elapse before the thumb tip has healed.
Loss of greater than 50% of the distal portion of the thumb pad, tendon denuded of sheath and soft tissue coverage, and bone stripped of its periosteum may jeopardize not only the function of the injured thumb but also the preservation of thumb length. Under these circumstances, more complex reconstructive procedures such as palmar advancement flaps, cross-finger flaps, and neurovascular island or radial sensory-innervated cross-finger flaps may be warranted. Each of these techniques is considered in detail in the following sections.
Palmar Advancement Flap
Originally described by Moberg, the palmar advancement flap provides a good reconstructive option for loss of greater than half of the distal thumb pad. It has the advantage of bringing well-innervated sensate palmar thumb skin distally to resurface the pad lesion, thereby restoring nearly normal sensory perception with durable skin and subcutaneous tissue. Resurfacing of the thumb tip is accomplished by advancement of a palmar flap containing the neurovascular structures, with or without proximal skin release and interpositional grafting. This flap has proved most useful in covering defects ranging from slightly greater than 1 cm to “quarter sized,” or as large as 2 cm. The thumb is uniquely suited for this flap because the thumb IP joint can be flexed as much as 45 degrees to provide sufficient advancement of the flap. Although some authors believe this degree of flexion does not result in long-term flexion deformity, in our practice, we have found that it does. Additionally, we have found that advancement of the flap by more than 1.5 cm is facilitated by a proximal transverse releasing incision, which can decrease the need for acute IP flexion and increase the amount of tissue that can be mobilized. Although the defect created by the releasing incision can be left to heal by secondary intention, coverage with a full-thickness skin graft provides a closed wound and decreases wound contraction. The proximal flap can also be advanced by a “V-Y” technique in which the proximal incision is designed as a “V” rather than perpendicular to the thumb.
Palmar Advancement Flap Without Proximal Releasing Incision
This technique is best for terminal distal phalangeal pad defects 1.5 cm or less in length. Under tourniquet control, necrotic and ragged bone is trimmed from the distal phalanx, and thorough soft tissue débridement is carried out ( Figure 48.2, A ). Midaxial incisions are made over the radial and ulnar sides of the thumb and extended proximally from the lesion to the proximal thumb crease. Placement of the incisions across the dorsal apices of the flexion creases facilitates dissection dorsal to the neurovascular bundles. The palmar flap is carefully dissected from the underlying flexor tendon sheath; the flap should include subcutaneous tissue and both neurovascular bundles (see Figure 48.2, B ). The mobility of the flap is tested by distal traction to determine whether any additional soft tissue undermining or releases are necessary. If tension is too great, the midaxial incisions can be extended proximally onto the thenar eminence. The MP and IP joints of the thumb are flexed 30 to 45 degrees. The distal edge of the flap is sutured to the remaining nail, nail bed, or terminal skin remnant, and radial and ulnar sutures are used to complete skin closure (see Figure 48.2, C ). Figure 48.2, E to G , shows a clinical example of the palmar advancement flap without a proximal incision in a patient who suffered a distal thumb amputation during an altercation.
Indications
- •
Palmar thumb pad defects greater than 1 cm but less than 2 cm long
- •
Exposed distal phalanx devoid of periosteum
Technical Points
- •
Perform thorough débridement of the defect.
- •
Incise skin in the midaxial line beginning at the wound and extending proximally on the radial and ulnar aspects of the thumb up to the proximal thumb crease.
- •
Dissect the flap, containing the subcutaneous tissue and both neurovascular bundles, from the flexor sheath.
- •
Test tension on the flap by providing distal traction.
- •
If additional length is necessary, extend incisions or dissection onto the thenar eminence.
- •
Flex thumb MP and IP joints to 30 to 45 degrees.
- •
Suture the distal flap to the remaining nail, nail bed, or skin.
- •
Apply nonadherent dressing and a thumb spica splint.
Postoperative Care
- •
Inspect the wound at 7 to 10 days.
- •
Switch to a thermoplastic thumb spica splint.
- •
Begin active range-of-motion exercises at 3 weeks.
- •
If necessary to achieve IP joint extension, dynamic splinting can start at 3 to 4 weeks.
Palmar Advancement Flap With Proximal Releasing Incision
Use of a proximal releasing incision allows the palmar advancement flap to cover defects up to 2.5 cm long. As in the case of a palmar flap without a releasing incision, appropriate bone and soft tissue débridement should be carried out under tourniquet hemostasis ( Figure 48.3, A ). Dissection begins at the radial and ulnar edges of the wound via midaxial incisions. How far proximal these midaxial incisions are carried depends on the method chosen to close or cover the wound created by the relaxing incision. If the necessary advancement is only slightly greater than that achievable without a relaxing incision, options such as ending each incision as a “Z”-plasty over the thenar eminence or creating a “V-Y” advancement flap just proximal to the proximal thumb crease may allow primary closure of all wounds. More often, however, when significant advancement is required, the midaxial incisions should be carried to the level of the proximal third of the proximal phalanx. At this point, a transverse incision should be used to connect the proximal ends of the incisions. The neurovascular bundles must be identified, protected, and carefully mobilized (see Figure 48.3, B ). It is more convenient and simpler to raise the flap in a distal-to-proximal direction, maintaining a plane of dissection just superficial to the flexor sheath. On reaching the proximal portions of the midaxial incisions, the flap consists of skin, subcutaneous tissue, and both neurovascular bundles. This “islandized” flap can be advanced to the thumb tip and sutured into place (see Figure 48.3, C ). As when insetting the standard palmar advancement flap, it may be necessary to flex both the IP and MP joints to relieve tension on the closure. The resulting gap between the proximal end of the flap and the proximal releasing incision is covered with a full-thickness skin graft harvested from the medial arm (preferred), hypothenar eminence, antecubital fossa, or groin (see Figure 48.3, D ).
Indication
- •
Same as for the standard palmar advancement flap, with defects greater than 2 cm and less than 2.5 cm long.
Technical Points
- •
Perform thorough débridement of the defect.
- •
Incise the skin in a midaxial line beginning at the wound and extending proximally on the radial and ulnar aspects of the thumb up to the proximal third of the proximal phalanx.
- •
Connect the midaxial incisions via a transverse palmar incision.
- •
Identify and mobilize the neurovascular bundles.
- •
Dissect the flap, containing the subcutaneous tissue and both neurovascular bundles, from the flexor sheath.
- •
Test tension on the flap by providing distal traction.
- •
If additional length is necessary, extend incisions or dissection onto the thenar eminence.
- •
Flex thumb MP and IP joints to 30 to 45 degrees.
- •
Suture the distal flap to the remaining nail, nail bed, or skin.
- •
Apply a full-thickness skin graft to the proximal thumb flap harvest site.
- •
Apply nonadherent dressing and a thumb spica splint.
Postoperative Care
- •
Inspect the wound at 7 to 10 days.
- •
Switch to a thermoplastic thumb spica splint.
- •
Begin active range-of-motion exercises at 3 weeks.
- •
If necessary to achieve extension, dynamic splinting can start at 3 to 4 weeks.
At the conclusion of either palmar advancement flap, a dressing consisting of antibiotic ointment, nonadherent gauze, fluffed cotton gauze, and a thumb spica splint is applied. Care should be taken in shaping the thumb spica to maintain the flexion applied to achieve a tension-free closure. The splint and dressings are removed to allow inspection of the flap and skin grafts (if used) after 7 to 10 days. Thereafter, a removable Orthoplast thumb spica splint is applied to prevent overextension of the thumb. After 3 weeks, the patient begins active range-of-motion exercises; if necessary to regain full extension, dynamic splinting can begin at around 4 weeks.
Although these flaps are used primarily in acute situations, they can also be employed for thumb resurfacing at a later time when inadequate coverage exists. Choosing the appropriate wound for reconstruction with these flaps provides the best chance for a successful outcome. The required advancement should not exceed 2.5 cm and should include, if at the upper end of this distance, plans for a proximal releasing incision. Despite the excellent dorsal vascularity of the thumb, it is possible to induce ischemia in the ungual area, particularly in smokers; therefore, it is advisable to avoid dissecting the pedicle too far. Other risks worth mentioning during preoperative counseling include sloughing of bits of bone or nail during the immediate postoperative period and the possibility of flexion contractures of the IP joints.
Heterodigital Flap Reconstruction
Loss of the entire palmar surface of the thumb distal phalanx presents a wound too great to be covered with a palmar advancement flap. Simple skin grafting may preserve length, but it does not restore durable, painless skin. Initially developed for coverage of exposed tendon or bone and for loss of a significant amount of skin and subcutaneous tissue from the palmar surface of the fingers, a cross-finger flap designed from the dorsal proximal phalanx of the index finger often provides excellent coverage of these lesions, with satisfactory skin and subcutaneous tissue and adequate recovery of sensation. This flap, and its innervated variations, substitutes a delayed skin flap from an adjacent digit for flaps historically based on cross-arm, thoracic ( Figure 48.4 ), or abdominal donor sites. The reliability and ease of performance of these flaps have made them the mainstay for larger tissue losses in the distal third of the thumb, despite the development of numerous more elaborate techniques, including transfer of the tip of the fifth finger, free toe pulp transfers, a one-stage advancement–rotational flap combination, “kite” or “flag” flaps from the index finger, a dorsal flap based on the first web space, or a flap hinged on the ulnar side of the thumb and rotated distally, as popularized by Brunelli ( Figure 48.5 ) .
Occasionally, irreparable damage to the digital nerves of the thumb, resulting in permanent sensory loss in the palmar tactile pad, accompanies soft tissue loss in the distal third of the thumb. A patient with this wound may suffer substantial disability owing to impairment of pinch and grasp function. Under these circumstances, it may be appropriate to use a neurovascular island pedicle transfer, as first suggested by Moberg and Littler. This technique is very demanding, however, and the quality of sensory return has been challenged.
Cross-Finger Flap to the Thumb
Under tourniquet hemostasis, acute wounds should be thoroughly débrided and the wound margins excised. Some attempt to convert the lesion into a square or rectangular defect may facilitate flap design and inset; however, this should not take precedence over preservation of viable palmar skin, especially along the radial aspect of the thumb, which represents the most distal aspect of the cross-finger flap. Blotting the wound with a sterile piece of paper produces a template corresponding in size to the defect. This template can be cut from the paper and traced onto the dorsal radial aspect of the index finger after adducting the thumb against the side of the index finger to determine the appropriate level for the base of the flap ( Figure 48.6, A ). Because of the unique rotational motion of the thumb, the base of the flap originates palmar to the midaxial line of the index finger and extends across the dorsum of the proximal phalanx as far as the defect size requires. A slightly oblique configuration of the donor flap aids in positioning it against the pad lesion.
Incisions are made along the proximal, ulnar, and distal borders of the flap through the skin and subcutaneous tissue down to the level of the paratenon. The flap is raised in an ulnar-to-radial direction in the plane just superficial to the extensor paratenon. As dissection proceeds radially toward the base of the flap, the cutaneous ligaments of Cleland must be incised to increase mobility of the flap. Dorsal veins running in the subcutaneous tissue can be divided with bipolar cautery, but small veins in the radial corner of the flap should be preserved to ensure its viability (see Figure 48.6, B ). On completion of dissection, the tourniquet is deflated, and hemostasis is achieved using bipolar cautery.
A full-thickness skin graft is patterned slightly larger than the donor defect and harvested from the ipsilateral medial arm (preferred), antecubital fossa, or groin. The graft excess is applied to the base of the flap as it spans the space between the apposed thumb and index finger. Inset of the flap to the proximal, radial, and distal thumb wound is performed using fine (5-0) nonabsorbable monofilament sutures. The skin graft is applied to the donor defect and sutured in place with fine (5-0) plain gut suture. The inset of the skin graft is completed by suturing to the ulnar aspect of the thumb defect, thereby creating a closed wound (see Figure 48.6, C and D ). The skin graft and flap should be covered with antibiotic ointment, a nonadherent dressing, followed by cotton gauze. The gauze overlying the skin graft should be conformed to the wound to serve as a bolster. These dressings are held in place by rolled cotton gauze, and the thumb and index finger are immobilized in a palmar splint extending across the hand and wrist.
Motion is permitted in the ulnar three fingers to prevent stiffness, and a dressing change at 5 to 7 days is used to assess the viability of the flap and the “take” of the graft. The flap can be safely divided after 14 to 21 days. Some recommend elevation of the wound edges and inset of the flap, as well as closure of the index donor site during division of the flap. Although this is possible, the wounds will heal just as effectively by secondary intention, without the risk of constricting either finger by attempting inset and closure. Daily dressing changes to the divided flap wounds are performed until complete closure has occurred. Active and passive range-of-motion exercises are begun immediately after division of the flap.
Satisfactory sensory return has been reported in several long-term studies of cross-finger flap performance. The technique is reliable and well tolerated by patients and provides sufficient padding for long-term heavy thumb use ( eFigure 48.1 ). Disadvantages and complications include a potentially unsightly defect over the dorsum of the index finger, which may be particularly annoying to children and women, and some occasional problems with digital joint stiffness or thumb web contracture.
Indication
- •
Loss of the entire palmar surface of the thumb distal to the IP joint
Technical Points
- •
Thoroughly débride the wound.
- •
Blot the wound with sterile paper to form a template.
- •
Align the thumb with the radial aspect of the index finger to determine the level for the base of the flap.
- •
Trace the template onto the dorsal index finger.
- •
Incise the proximal, ulnar, and distal borders of the flap.
- •
Preserve the small veins in the radial corner of the flap.
- •
Raise the flap in a plane just superficial to the extensor paratenon.
- •
On the radial aspect of the flap, divide the Cleland ligaments to increase mobility of the flap.
- •
Deflate the tourniquet and achieve hemostasis before flap inset.
- •
Inset the flap along the proximal, radial, and distal margins of the wound.
- •
Harvest a full-thickness skin graft (medial arm) and inset this in the donor site using 5-0 plain gut sutures.
- •
Apply antibiotic ointment and a nonadherent gauze dressing to the flap and graft.
- •
Immobilize the thumb and index finger via a palmar splint crossing the hand and wrist.
Postoperative Care
- •
Inspect the wound in 5 to 7 days.
- •
Divide the base of the flap at 10 to 14 days.
- •
Allow the divided bridge to heal by secondary intention.
- •
Begin active range-of-motion exercises immediately after flap division.
Innervated Cross-Finger Flap
Protective sensation and two-point discrimination return most predictably after cross-finger flaps in patients younger than 20 years; in patients older than 40, nearly half fail to regain protective sensation. In an attempt to improve on these outcomes, large cross-finger pedicle flaps that carry a sensory branch of the radial nerve have been described. With the exception of the axial, bipedicled neurovascular island flap developed by Paneva-Holevich and Holevich, each of these flaps differs from a traditional cross-finger flap primarily in that additional dissection over the first web space is used to facilitate inclusion and transposition of a dorsal sensory branch of the radial nerve. Walker and colleagues determined that the ultimate sensibility of these flaps is a mixture of the median and radial nerves, and Hastings described a “dual innervated cross-finger” or island flap that coapts the dorsal sensory branch of the index radial digital nerve to the ulnar digital nerve of the thumb in an effort to improve cortical recognition of the flap as a thumb. Other variations have also been described, and though it is rarely required, the procedure has a definite place among the reconstructive options for restoring thumb sensibility.
Radial-Innervated Cross-Finger Flap.
After appropriate débridement under tourniquet hemostasis, a pattern matching the size of the acute defect or the defect to be created to provide sensory restoration to the denervated thumb is created. Markings for the size and location of the cross-finger flap are carried out in a manner identical to that described for the noninnervated cross-finger flap. If necessary, the flap can be extended over the MP joint for the resurfacing of larger defects. Beginning at the midpoint of the proximal transverse outline of the flap, an oblique incision extends proximally over the dorsal ulnar border of the first web space to a level several centimeters proximal to the midportion of the thumb web ( Figure 48.7, A ). A large dorsal sensory branch of the radial nerve may be identified on the muscle fascia in the proximal portion of this incision and traced distally into the proximal margin of the flap. Complete mobilization of the nerve from the proximal edge of the flap to the base of the web space incision is necessary to prevent undue tension on the nerve after transposition. Small branches of the nerve encountered during mobilization should be divided.
Once the radial sensory branch has been mobilized, the cross-finger flap is incised and elevated, as for a standard cross-finger flap. A solitary but significant difference from the standard flap is that care must be taken when incising the proximal transverse border of the flap to avoid injury to the radial sensory branch as it enters the flap. When the flap has been mobilized to its base, the thumb is brought along the side of the index finger to check the positioning of the flap into the recipient defect (see Figure 48.7, B ).
A connecting incision is made along the midaxial ulnar border of the thumb and carried proximally to the previous oblique incision extending from the flap. At the time of flap attachment, the nerve is carefully transposed from the dorsum of the index ray to the ulnar thumb incision after undermining has provided a satisfactory trough in which it can lie without tension. Suturing of the ulnar thumb incision and the connecting dorsal radial index incision secures the position of the nerve, and the defect over the dorsum of the proximal phalanx is covered with a full-thickness skin graft. As in the standard cross-finger flap, enough graft is harvested to provide coverage of the exposed pedicle by suturing into the free ulnar edge of the thumb defect (see Figure 48.7, C and D ).
A dressing and splint identical to that described for the standard cross-finger flap are applied. Flap monitoring and division are also as described earlier. In addition to active and passive motion rehabilitation, a protocol of gradually increasing pressure stimuli is added, with the goal of increasing appropriate cortical recognition of the transferred flap. Risks inherent in using the innervated cross-finger flap include those related to damage to the mobilized branch of the radial sensory nerve secondary to undue tension or manipulation. Sensory return may be only protective, and the patient may continue to interpret thumb sensation as that of the dorsal index finger. Nonetheless, the radial-innervated cross-finger flap is a useful procedure when one is faced with irreparable sensory damage to the thumb and no other source is available for reconstruction ( eFigure 48.2 ).
Indications
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Similar to those for the cross-finger flap
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Damage to the terminal digital nerve with tissue loss, as for the standard cross-finger flap
Technical Points
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Débride, create a template, and outline the flap, as for the standard cross-finger flap.
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Incise the skin obliquely, beginning at the midportion of the proximal flap incision and extending along the ulnar border of the first web space.
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Stop the incision a few centimeters proximal to the midportion of the thumb web.
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Bluntly dissect a branch of the radial sensory nerve, typically found running deep on the muscle fascia.
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Trace the nerve up to the flap.
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Dissect the flap as for the standard cross-finger flap, taking care not to divide the nerve as it enters the flap.
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Incise from the proximal margin of the thumb wound along the radial aspect of the first web space.
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Stop this incision at the proximal end of the incision used to identify the radial sensory nerve branch.
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Deflate the tourniquet and achieve hemostasis.
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Bluntly dissect and elevate the radial sensory nerve branch.
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During inset of the flap, transpose the nerve to the incision created on the ulnar aspect of the thumb.
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Harvest a graft large enough to allow coverage of the harvest site as well as the nerve pedicle at the proximal flap inset.
Postoperative Care
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Same as for the standard cross-finger flap
Dual Innervated Cross-Finger Flap.
Under tourniquet hemostasis, thumb débridement, pattern creation, and flap design are carried out as described for the standard cross-finger flap. An incision is made from the proximal aspect of the flap along the radial aspect of the index metacarpal to the recess between the base of the index metacarpal and the extensor pollicis longus. A second incision is extended distally along the dorsal ulnar aspect of the thumb metacarpal to the MP joint and the more distal thumb defect just palmar to the midaxial line ( Figure 48.8, A ).
Flap elevation is initiated along the distal and ulnar incisions on the index finger. As the incision is carried down to the level of the paratenon, small veins are divided with bipolar electrocautery. The flap is elevated in a dorsal-to-palmar direction while preserving the paratenon of the extensor mechanism and including all neurovascular structures within the flap. Along the incision coursing proximal over the index metacarpal, flaps are elevated superficial to the neurovascular structures. No attempt is made to separately dissect out the two to four terminal branches of the dorsal sensory radial nerve to the dorsal index finger. The subcutaneous tissue surrounding the dorsal sensory radial nerve contains veins and, in most instances, the first dorsal intermetacarpal artery; a narrow 0.5- to 1-cm-wide strip of this subcutaneous tissue should be raised down to the level of the investing muscle fascia to incorporate these nerve branches and, if the flap is to be transferred as an island pedicle, the artery and veins (see Figure 48.8, B ). If an island flap is planned, the first dorsal intermetacarpal artery should be identified proximally before raising the subcutaneous portion of the flap to ensure that it is contained in the pedicle. Although, as stated by Foucher, the artery most often runs superficial to the fascia, it may run deep to the fascia in 15% of cases or consist of two vessels, one superficial and one deep, in 10%. At the level of the MP joint, the dorsal branch from the index radial digital nerve (median nerve distribution) is identified and dissected back to its origin. The connecting incision to the thumb is completed, and the ulnar digital nerve amputation stump proximal to the thumb defect is identified.
Transposition of the flap with the dorsal sensory radial nerve branches is accomplished as described earlier, and the inset begins radially (see Figure 48.8, C and D ). Before completion of the proximal and distal inset, neurorrhaphy of the palmar ulnar digital nerve of the thumb to the more distal dorsal sensory nerve branch of the transposed flap is accomplished under the operating microscope ( eFigure 48.3 ). The connecting incisions are closed, and skin grafts are applied to the donor area.
Postoperative care, flap division, and rehabilitation are identical to these steps for the radial-innervated cross-finger flap previously described.
First Dorsal Metacarpal Artery Island Flap
The first dorsal metacarpal artery (FDMA) flap was popularized as a pure island flap (kite flap) by Foucher in 1979. In many ways, this flap is similar in design to the radial-innervated cross-finger flap. However, it is transferred as a pure island flap carrying the FDMA, subcutaneous veins, and branches of the radial sensory nerve in a single stage, thus eliminating the need for prolonged immobilization and potential long-term stiffness. The FDMA island flap can reach the volar and dorsal aspects of the distal thumb and is considered a versatile workhorse flap for innervated distal thumb soft tissue coverage.
As with the other described procedures, the operation begins with appropriate débridement. Then a pattern matching the size of the defect is drawn on the dorsum of the index finger proximal phalanx ( Figure 48.9 ). To avoid scar contracture, the proximal limit of the flap is the MP joint, and the distal limit is the proximal IP joint. The course of the FDMA is mapped with the aid of a handheld pencil Doppler from the radial aspect of the index MP joint to its proximal pivot point, located at the juncture of the proximal first and second metacarpals. Under tourniquet hemostasis, the flap is elevated in the loose areolar plane above the extensor tendon paratenon. Dissection generally moves from distal to proximal and from the ulnar to the radial side. Extreme care must be taken at the radial border of the MP joint because this is where the FDMA enters the flap’s subcutaneous network.
At the level of the MP joint, a teardrop-shaped incision (preferably) (see Figure 48.9, G ) or a lazy-“S” proximal incision is made, and the skin is elevated in the deep dermal plane superficial to the adipose tissues. The pedicle is dissected by incising the interosseous fascia at the radial edge of the muscle and second metacarpal periosteum at the ulnar edge. The deep periosteal incision is carried radially and deep to the muscle fascia. The dorsal veins and sensory branches of the radial nerve that typically enter the flap over the ulnar border of the MP joint are included in the pedicle. The pedicle is dissected back to the pivot point at the juncture of the first and second metacarpals.
The tourniquet is released, and the vascularity of the flap is assessed. Once viability is assured, the flap is passed to the defect through a subcutaneous tunnel and sutured. In our experience, we have found that the subcutaneous tunnel is often too narrow and must be opened to avoid unnecessary tension on the flap. The teardrop flap design allows a tension-free closure in this instance and is recommended. The index finger dorsal donor site defect is covered with a full-thickness skin graft obtained from the medial arm. The skin graft is covered with a nonadherent dressing and moist gauze; a bulky dressing is applied to the entire hand. The dressing over the distal tip of the thumb should be opened to expose the most distal portion of the flap and allow monitoring of viability. A full dressing change is carried out at 7 to 10 days, and motion is permitted.
Potential complications include flap vascular compromise and index finger donor site morbidity, such as stiffness, cold intolerance, hypertrophic scarring, and neuroma.
Neurovascular Island Pedicle Flap
Although developed before the innervated cross-finger flap, the neurovascular island pedicle flap now plays a smaller role in the armamentarium of hand surgeons. This stems not only from the greater technical difficulty of the procedure but also from the need to sacrifice palmar sensation along the ulnar aspect of another digit. As a result, important preoperative considerations include selection of a donor digit and determination of the amount of digital skin and subcutaneous tissue to be brought with the pedicle. The main factor in choosing the donor digit is the status of the median nerve; if median nerve function is intact, the ulnar aspect of the long finger provides a long neurovascular pedicle that can facilitate transposition of the flap. In the absence of median nerve function, an ulnar-innervated digit must be chosen; under these circumstances, the ulnar aspect of the ring finger may serve as a donor.
In either setting, the ulnar aspects of the digits do not participate in pinch, making the sacrifice of tactile surface an acceptable deficit. In general, the size of the flap should correspond to the deficit created by adequate débridement of the scarred and insensate tissue along the thumb defect; occasionally, it may be reasonable to use an “extended” neurovascular island transfer that consists of almost the entire ulnar palmar half of the donor digit to provide the widest possible areas of sensory restoration. Thompson emphasized that it is not necessary to apply the flap to the absolute tip of the thumb unless it is required for soft tissue coverage and that the position should favor the ulnar side of the thumb.
Variations have involved attempts to improve innervation, as well as the creative use of extended flaps. Some authors have advocated suturing the divided proper digital nerve of the neurovascular island pedicle flap to the distal stump of a previously severed thumb digital nerve to improve sensation and help prevent neuromas. Chen and Noordhoff reported one case in which the entire distal phalanx of the thumb was resurfaced with twin neurovascular island flaps taken from the ulnar and radial sides of the middle and ring fingers.
Before beginning, it is necessary to determine the size of the thumb defect to be resurfaced; this measurement mandates the size of the flap. Because most clinical conditions warrant the use of an extended flap involving the entire length of a donor digit, this technique is described here ( Figure 48.10, A ).
