Littler extensively reviewed the history of thumb reconstruction, a field in which he has been a major contributor.¹ Nicoladoni introduced two techniques, namely, osteoplastic reconstruction and toe transfer through the pedicle method.² Guermonprez was among the first to pollicize a finger, a technique subsequently refined by the island principle, attributed to Littler and Gosset.³^–⁷ A mobile and sensate thumb was obtained, but at the price of sacrificing a finger. Matev originated the technique of progressive lengthening through distraction, maintaining good sensibility and improving length.^8,⁹ A major advance was the introduction of microvascular techniques, which led to microvascular free toe-to-hand transfer. First- and second-toe transfers were initially described, followed by refined techniques allowing the surgeon to improve the appearance of the reconstructed thumb while at the same time minimizing donor site morbidity.

Basic science/disease process

By far, the most common “disease process” necessitating thumb reconstruction is traumatic injury. The majority of these patients are working-age males. Within the larger trauma classification, thumb injury can be the result of a variety of different mechanisms. These include sharp cut, avulsion, and crush. There are some mechanisms that have characteristics of more than one injury type. This phenomenon is best illustrated by saw and lawnmower injuries, which have both cutting and crushing components, resulting in a larger zone of injury.

Other insults that can result in thumb loss requiring reconstruction are infections and neoplasms. Because tumors are less acute than trauma or infections, thumb reconstruction planning can be more deliberate, and can even be performed at the time of tumor extirpation.¹⁰

Diagnosis/patient presentation

The diagnosis of thumb trauma is relatively straightforward, as there will be, in most cases, open wounds. It is important to obtain history regarding the mechanism and other details of the traumatic insult, time from injury to presentation, handedness, occupation, pertinent social issues such as tobacco use, and pertinent medical problems (including problems that can compromise peripheral circulation and/or wound healing). If feasible, replantation of the amputated thumb will generally yield a thumb that is superior in appearance and function to any other type of thumb reconstruction. However, this is sometimes not possible, in which case, other reconstruction methods are employed.

Evaluation of the traumatically injured thumb requires complete evaluation of all tissues of the thumb including integumentary, neural, vascular, and musculoskeletal. The wound(s) on the thumb should be carefully inspected. The integrity of the sensory nerves supplying the thumb is assessed. Assessing any compromise in the circulation to the thumb is crucial, as is assessing the feasibility of arterial and venous reconstruction. Finally, assessment of the integrity of the thumb tendons and skeletal structures is performed. Radiographs are a necessity in evaluating thumb skeletal structure.

Evaluation of the thumb following infection is similar to that following trauma. All tissues must be assessed, making particular note of the cutaneous defect requiring reconstruction.

Evaluation of a thumb affected by a tumor will be guided by the tumor itself. Specifically, tumor type and grade will determine the extent of extirpation that will need to be determined prior to reconstruction. This will also determine which procedures will be needed either intraoperatively (sentinel lymph node biopsy, lymphadenectomy) or perioperatively (radiation, chemotherapy).

Patient selection

Because there are many ways to reconstruct a deficient thumb, patients must be educated about the various options so that they may make an informed decision as to which type of reconstruction will serve them best in both the personal and professional settings.

Many thumb injuries occur in the workplace, and these patients will be affected by the injury because their work involves significant hand use. In these patients especially, it is essential to work toward a thumb that has adequate length for both gripping and pinching, is stable during activities, has reasonable motion, and, importantly, is sensate in order to give tactile feedback during these actions and to prevent recurrent ulceration or injury. That said, adequate length, stability, motion, and sensibility are the end-goals for any patient requiring thumb reconstruction, regardless of profession or vocation.¹¹

In addition to patient input regarding reconstructive methods, the patient must also commit to the reconstructive process. Most of the reconstructive options will result in edema, stiffness, and pain in the near term; therefore, adherence to a supervised hand therapy program is critical to reconstruction success.

As with any type of reconstructive surgery, medical optimization prior to procedure(s) allows superior outcomes. This includes, but is not limited to, tobacco cessation, cardiopulmonary stabilization, and good diabetes control. If the thumb is being reconstructed following cancer extirpation, the physician must ensure adequate local disease control prior to reconstruction, and coordination of the patient’s reconstruction with any systemic adjuvant therapies that will be required. Similarly, in patients for whom a thumb is deficient due to infection, infection control prior to reconstruction is paramount.

The most important factor in patient selection is the amount and nature of tissue loss that must be reconstructed. The level of amputation is the easiest way to classify thumb deficiencies, and is listed in thirds ¹² (Fig. 13.1). The distal third extends from the interphalangeal joint to the thumb tip. The middle third is the portion between interphalangeal joint and the metacarpal neck, and the proximal third is from metacarpal neck to the carpometacarpal joint. Each amputation level presents unique challenges for patient and physician, and each level can be reconstructed with multiple modalities.

Fig. 13.1 Thumb loss classification, divided into thirds. Distal third is from thumb tip to interphalangeal joint. Middle third is interphalangeal joint to metacarpal neck. Proximal third is metacarpal neck to carpometacarpal joint.

Treatment/surgical technique

Distal third

Thumb distal-third amputations rarely, if ever, require restoration of length, as a thumb amputated through the interphalangeal joint remains very functional.¹² Therefore, the chief goals of thumb tip reconstruction are soft-tissue coverage of bone and length preservation. When there is no bone exposed at the tip of the thumb, closure can be achieved with either healing by secondary intention or skin grafting. Secondary healing of tip amputations has been shown to result in a stable scar and good two-point discrimination, and is therefore a relatively easy (and usually the preferred) method of achieving coverage.¹³ Secondary healing by wound contracture has the advantage of bringing stable, sensate skin together to close the defect, as opposed to skin grafts, which remain insensate. Defects up to 1.5 cm in diameter with no bone exposure can be effectively treated with dressing changes. Daily dressing changes with petroleum or bismuth-impregnated gauze are relatively easy for patients. Larger defects with a stable base, however, require skin grafting. Full-thickness grafts are usually preferred, as they are more durable and stable, especially in the contact areas subject to pressure and shear. Small full- or split-thickness skin grafts can be harvested from the hypothenar eminence or the volar wrist crease. Larger skin grafts, however, are best harvested from the groin crease.

When phalangeal bone is exposed at the thumb tip, vascularized coverage is required to preserve length, and there are several flaps that can accomplish these goals. The main criteria for flap selection are defect size and location of soft-tissue loss, specifically if it is volar, dorsal, or at the tip. The V-Y advancement flap described by Atasoy et al. provides good coverage of the tip of the distal phalanx when only a very small amount of bone is exposed ¹⁴ (Fig. 13.2). The technique involves incising the volar pulp of the thumb in a V shape. Scissors are then used to spread the subcutaneous tissue carefully. The subcutaneous attachments deep to the flap, which provide the neurovascular supply to the flap, are left intact. The flap is then advanced distally to close the defect and the proximal aspect of the V is closed side to side, thereby creating the Y shape of the final scar. In practice, there is limited application for this flap due to the limited advancement that is possible without devascularizing the flap.

Fig. 13.2 Thumb tip closure via volar V-Y advancement flap. The flap is perfused by small vessels traversing the subcutaneous tissues immediately deep to the flap.

The neurovascular volar advancement flap, which goes by the eponym of the Moberg flap, is well suited to cover volar and tip defects of the thumb.¹¹ It is often described as an advancement flap, but in reality, the amount of advancement achieved with the conventional rectangular Moberg flap is limited. Instead, the elevation of the flap allows flexion of the interphalangeal joint of the thumb, thereby allowing the flap to appear to “advance” distally (Fig. 13.3). To elevate the flap, one incises the mid-lateral lines on either side of the thumb, down to the base of the proximal phalanx. The flap is then elevated from the deeper tissues, directly off the flexor retinaculum, with sharp dissection. The flap includes both neurovascular bundles and all of the subcutaneous tissue down to the flexor tendon sheath. The interphalangeal joint is flexed, and the flap is inset at the tip. If necessary, a Kirschner wire can be placed across the interphalangeal joint to stabilize it, though this is seldom required. This flap can easily cover a defect of 1–2 cm² (Fig. 13.4). A variation of the Moberg flap is an island flap in which flap is incised transversely across the proximal base, and the only remaining attachments are the two neurovascular bundles. Unlike the conventional Moberg flap, this method will allow a small amount of actual advancement, thereby covering more distal defects. The proximal gap at the base of the flap will then require a small skin graft.

Fig. 13.3 Moberg thumb volar advancement flap. It is a sensate flap by virtue of the digital nerves remaining in the flap, and is perfused by the digital vessels.

Fig. 13.4 Thumb reconstructed with a Moberg flap for a distal amputation. Note the flexed posture of the interphalangeal joint.

The cross-finger flap from the index finger is an excellent reconstructive technique for larger volar and tip defects of the thumb, up to 2–3 cm².¹⁵ The tissue transferred is reliable and durable.¹⁶ The chief disadvantages to this technique are thumb coaptation to the index finger for 2–3 weeks, and the need for a skin graft on the index donor site. A radially based rectangular flap is marked on the dorsum of the index proximal phalanx that extends from the ulnar to the radial mid-lateral lines (Fig. 13.5). The flap is incised and elevated from ulnar to radial in the plane between the subcutaneous tissues and the extensor mechanism. It is critically important to leave the paratenon on the extensor to allow skin grafting. Upon reaching the radial aspect of the flap, one must release Cleland’s ligaments along the length of the base of the flap to prevent kinking at the flap “hinge.” The flap is then sutured to the thumb – this may require some trial and error to find the best flap orientation (Fig. 13.6). A full-thickness skin graft is then sutured to the dorsum of the index finger. A bulky thumb splint is applied. At 2 or 3 weeks, the flap is divided and the inset to the thumb is completed (Fig. 13.7). After division, aggressive range-of-motion therapy for both the thumb and index finger should begin.

Fig. 13.5 Diagrammatic representation of the cross-finger flap to the thumb. The flap is elevated from the dorsum of the index finger proximal phalanx and inset to the thumb volar defect. Once elevated, Cleland’s ligament of the index radial neurovascular bundle can restrain and kink the flap, therefore release of this ligament allows greater flap freedom.

Fig. 13.6 Thumb tip defect resurfaced with a cross-finger flap from the index finger.

Fig. 13.7 Reconstructed thumb following division of the cross-finger flap seen in Figure 13.6.

The neurovascular island flap attributed to Littler is a valuable tool in thumb reconstruction.¹⁷ It is rarely used as a primary coverage flap, although it is certainly possible to use it in that manner. Rather, its most common use is for the restoration of sensation to the thumb pulp following reconstruction.^17,¹⁸ The flap is based on the ulnar neurovascular bundle of either the middle or ring finger (Fig. 13.8). The ulnar side of the digit is chosen because its loss will have minimal effect on grip and pinch activities. The dimensions of the flap needed are marked on the ulnar pulp of the chosen donor finger. Often, the flap will require harvesting of skin over the distal and middle phalanges of the donor finger. The flap is incised, and a mid-lateral incision proceeding from the proximal aspect of the flap is made. The flap is elevated from distal to proximal, and the entire ulnar neurovascular bundle is elevated in continuity with the flap. It is critical to raise the neurovascular bundle with a fairly thick cuff of surrounding fatty tissue containing the vasa vasorum of the artery, as that is the only source of venous outflow for the flap. Failure to do this will result in flap congestion. One must dissect fairly proximally in the palm to allow adequate transposition to the thumb, and the other branch of the common digital artery (i.e., the radial digital artery to the ring or small finger) must be divided. The common digital nerve can be split along the fascicles to allow adequate flap mobility. The flap can then be transposed to the thumb either via subcutaneous tunnel, or a connecting incision from the donor site to the thumb can be made (Fig. 13.9). The flap is then inset into the volar defect of the thumb. The donor site is grafted with full-thickness skin. In addition to postoperative restoration of motion, patients must work with a hand therapist on sensory re-education of the thumb.