results to reconstruction. Optimal thumb function is achieved with the original thumb itself; so, where possible replantation remains the ideal option for an amputated thumb in all but the most distal cases. Even a stiff replanted thumb is normally superior in aesthetics and function to an alternative reconstruction. However, there are always exceptions to any rule, and each case should be assessed individually (e.g., the amputated part may be too damaged and some patients may opt for terminalization to facilitate a speedier return to work, especially where the amputation is fairly distal). The importance of the thumb in overall hand function is well recognized and estimated as 40% (not 75%) of total hand function. It is required for many simple and complex hand movements acting as a post for opposition against the other digits. Thumb injuries are classified as proximal, middle, and distal third injuries (rather than by mechanism) and their management is typically guided by this classification (Fig. 89.1). Trauma in young adult males represents the most common etiology for acquired thumb loss. Although replantation should be performed as an emergency, definitive secondary reconstruction need not be done so urgently and can be delayed until the soft tissues have stabilized and the patient has had sufficient time to assess their own function and give thought to their reconstructive options. In order to facilitate the optimum secondary reconstruction, there may need to be an acute partial reconstruction, for example, free tissue transfer to preserve first web and cover remaining thumb metacarpal prior to subsequent definitive reconstruction.1–5
Free toe transfer is more commonly used for delayed reconstructions, but it may be carried out acutely if there are suitable recipient soft tissues and bone, the wound is clean and healthy, and appropriate informed consent has been obtained. Distal third B A Proximal Third Middle third A. Proximal B. Distal Fig. 89.1 Areas of thumb loss: distal third, middle third, and proximal third. The middle third is subdivided into proximal (A) and distal (B). A cross-finger flap from the index finger would not reach the proximal or radial extent of a defect overlying the proximal phalanx and metacarpophalangeal (MCP) joint. This flap is better suited to defects over the distal phalanx and interphalangeal (IP) joint. Full-thickness skin grafts are sometimes used for pulp defects, but sensory return is better with split-thickness grafts, healing by secondary intent, or homodigital flaps. Wraparound flaps are more likely to be performed urgently than full toe transfers, such as when there is exposed bone and immediate soft-tissue cover is required, but are not usually recommended for young children because of subsequent growth restriction. An amputation through the carpometacarpal (CMC) joint might be better reconstructed with pollicization. The great toe would not provide sufficient length and, because it is usually around 20% wider than the thumb, the aesthetic outcome is not ideal. The donor site is also not aesthetically pleasing, may require skin grafting, and can cause functional problems for some patients.1–4
3. You have a patient with a 1.5 × 1.5 cm defect of the thumb pulp with exposed bone. Which one of the following is The Moberg advancement flap may be used for thumb tip defects of up to 50% of the volar pulp surface. The standard Moberg flap can be advanced about 1 cm but requires further release at the base of the flap to move the 1.5 cm required in this case (Fig. 89.2). A number of modifications of the Moberg flap have been described to increase flap reach. These include advancing the flap in a V-Y fashion, or transversely releasing the proximal skin and applying a full-thickness skin graft to the donor site. Straight midlateral incisions are made to elevate the flap and the volar skin is advanced with both ulnar and radial neurovascular bundles superficial to the flexor tendon sheath. This generally requires some flexion of both the MCP and IP joints during inset, which is not always fully corrected with physiotherapy. The thumb is functionally most useful with some flexion at the IP and MCP joints anyway, so a small loss of extension is generally of little concern.1–5 A B C Fig. 89.2 Volar advancement flap (Moberg flap). A, Arc to the distal phalanx of the thumb. B, Elevation of the flap. C, Coverage of the distal phalanx of the thumb.
4. Morrison WA, O’Brien BM, MacLeod AM. Thumb reconstruction with a free neurovascular wrap-around flap from the big toe. J Hand Surg Am 1980;5(6):575–583
5. Pet MA, Ko JH, Vedder NB. Reconstruction of the traumatized thumb. Plast Reconstr Surg 2014;134(6):1235–1245
Lengthening of the thumb metacarpal with distraction osteogenesis can be useful to provide an increased total thumb length following injury in the proximal third. In order to perform this, two-thirds of the metacarpal must be remaining (not 50%) and a robust soft-tissue envelope must be present. When using this technique, up to 3.5 cm of lengthening can be expected over a 4- to 6-week period at a rate of 1 mm lengthening per day. Many patients over 25 years of age may benefit from additional bone grafting at the site of distraction osteogenesis to improve the rate of union.1 The soft-tissue envelope may not tolerate distraction if there is scarring or previous skin-grafted tissue and this may require revision prior to distraction. Most patients will need a subsequent web space deepening procedure as part of this reconstructive approach.
Pollicization is a useful and reliable procedure for complete thumb reconstruction. It results in minimal sacrifice is classically used and the EIP (extensor indicis proprius) becomes the new EPL (extensor pollicis longus). The MCP joint (not CMC joint) becomes the new thumb CMC joint as the digit is shortened. The first dorsal interosseous muscle becomes the new abductor pollicis brevis (not the APL [abductor pollicis longus]), the flexor digitorum profundus (not FDS [flexor digitorum superficialis]) becomes the new FPL (flexor pollicis longus), and the proximal phalanx becomes the metacarpal. The key structures involved in converting the index finger to a thumb are shown below (Table 89.1). Kozin1 presented his modifications of the concept, technical details, and outcome of pollicization. The original concept was brought to prominence by Buck-Gramcko in 19712 after his experience treating patients affected by thalidomide. Table 89.1 Structural Changes During Pollicization Initial Index Finger Structure Reconstructed Thumb Structure Metacarpal head Trapezium Proximal phalanx Metacarpal Middle phalanx Proximal phalanx Distal phalanx Distal phalanx Extensor digitorum communis Abductor pollicis longus Extensor indices proprius Extensor pollicis longus First dorsal interosseous Abductor pollicis brevis First palmar interosseous Adductor pollicis
Toe to thumb transfer is an effective way to reconstruct an absent or deficient thumb and has become the standard of care for amputations distal to the CMC joint. The choices for toe to hand include great or second toe. The great toe is historically the most common choice and has some advantages and disadvantages as compared with the second toe. There are a number of technical points to consider in planning and performing surgery.1,2 There is often sufficient length in a transferred toe without using the metatarsal, but if required, a second toe donor site is usually better tolerated than a great toe due to the role of the great toe metatarsal in weight bearing. An oblique osteotomy through the metatarsal helps improve alignment and range of motion in the new thumb, as the toe metatarsophalangeal (MTP) joints naturally tend to hyperextend a great deal, which can be undesirable in the reconstructed thumb. Great toe transfers are generally stronger than second toe transfers. Although there is debate about which is more aesthetically pleasing, the great toe is usually about 20% broader than the thumb which it is replacing, whereas the second toe is usually noticeably thinner with a short nail. This is variable between individuals. The arterial supply to both is most commonly via the first dorsal metatarsal artery; however, there is considerable variation. An ipsilateral great toe orientates the first dorsal metatarsal artery more favorably in the first dorsal web space for anastomosis. The second toe donor site usually closes directly, but the great toe may require skin grafting.
There are numerous ways to transfer different components of the great toe and second toes. All of the above options involve harvesting bone and soft tissues with the exception of the wraparound technique which is a soft tissue plus nail-only flap that is transferred from the great toe. Osseous support, as required in this case, is provided by a bone graft such as that from the iliac crest. The advantages of this flap are that it provides good sensation, adequate strength, better aesthetics, and less donor site morbidity. It is therefore particularly useful in cases where there is exposed retained bone length to cover, or less overall length required such that a nonvascularized bone graft within the wraparound flap will suffice. The disadvantages of this flap are that it is technically demanding to raise, and where a bone graft is used there is a risk of bone resorption and no joint for motion within the reconstructed length. This flap should be avoided in children because of growth restriction. The trimmed toe technique can be an elegant method for thumb reconstruction that harvests bone but involves a longitudinal osteotomy with trimming of the toe such that the size match is better than a traditional great toe transfer. Again, this is a more complicated procedure and should be avoided in children. A partial toe transfer is indicated in partial thumb defects, which may be bony or soft tissue related. Current evidence suggests there is no significant difference in outcomes between different toe transfer techniques1; so, reconstruction selection should be individualized to the patient, the defect, and the expertise of the treating surgeon. The following summary from the parent text is a useful guide to different toe transfer options: At or distal to IP joint • Partial toe transfer or free neurovascular island flap from first webspace. Through proximal phalanx with intact MCP joint • Wraparound transfer (better appearance than great toe) • Trimmed toe provides better aesthetics with preservation of joint mobility • Great toe provides best strength. Distal half of metacarpal • Great toe is an excellent option, harvested at MTP joint. • If the great toe is too short, then the second toe should be used. Proximal half of metacarpal with CMC joint preserved • Second toe is the best option due to additional metatarsal length. • Second toe is skin deficient proximally over metatarsal; secondary coverage procedure may be required.