Useful concepts and techniques that help to optimize functional and esthetic results

Because of space limitations, the reader is referred to other reviews and published descriptions of the various composite toe transplantations: partial [16,17,19], total [41,42], and wrap-around [25,26] second toe transplantations; third toe transplantation [43]; combined second and third [3133,39] or third and fourth [44] toe transplantations; and the pulp/hemipulp [17,22,45-47], vascularized nail [23,48] and first-web neurosensory flaps [46,47,49,50]. The authors have attempted to distil specific techniques and concepts from their experience that have proved helpful and are applicable to several types of toe harvest; these are highlighted in the following sections. They aim to ease vascular pedicle dissections, lessen donor site morbidity, and improve global esthetic and functional results in the hand reconstructed with toe transplantation(s).

Multiple team approach

It is always preferable for two microsurgical teams to work simultaneously at the hand and foot to reduce overall operative time, and thus patient and surgeon fatigue [27,40]. Intraoperative assessment of the exact length of tendons and neu-rovascular structures required by the hand from the foot before dividing them is expedited by this approach. Additional microsurgical teams should be recruited as necessary for simultaneous bilateral multiple toe harvests, such as for bilateral metacarpal hand reconstructions.

Dissect the toe vascular pedicles in a retrograde fashion

The blood supply of the second and great toes depends on the dorsal and plantar vascular systems. The dorsal system, which is usually dominant, extends from the dorsalis pedis artery, which passes along the dorsum of the foot to become the first dorsal metatarsal artery (FDMA), and then transmits a branch to the first plantar metatarsal artery (FPMA). The FPMA arises from the union of the plantar arch and the deep plantar artery. Multiple variations of the dorsal and plantar vasculature exist, however, and have been previously documented and classified [27,51,52].

Most descriptions of toe harvest begin on the dorsum of the foot proximal to the origin of the FDMA and proceed in an anterograde fashion toward the web space [51,52]. It is, however, much more straightforward to identify immediately which vascular system is dominant by beginning dissection in the web space; the smaller artery can be ligated (Fig. 4) [27,53]. By tracing the pedicle retrograde, more proximal anatomic variations need no longer be a problem and routine preoperative angiography becomes unnecessary [27,53]. Dissection of the FDMA is less demanding, and it should be chosen as the pedicle artery in the 10% of cases in which neither system dominates [27,53]. A dominant FPMA, which occurs in approximately 20% of cases, can be dissected in the plantar foot up to the deep perforator communicating between the two systems [27,53]. It is preferable to extend the FPMA at its origin with a vein graft if a longer pedicle is needed instead of dissecting through the foot to reach the dorsalis pedis artery, because this tedious stage of dissection may increase foot morbidity as well as the risk of pedicle injury [27,53]. A single superficial dorsal vein is usually sufficient to drain all types of toe harvest [27]. All toe transplants should be allowed to perfuse after harvest for at least 20 minutes before division of their vascular pedicles.

Dissection of the other lesser toes occurs in much the same fashion, starting at the respective web space. The combined second and third toe transplant unit should include a second pedicle artery for backup should perfusion of the third toe be suspect after arterial anastomosis, but a single dominant FDMA or FPMA usually suffices [54]. Likewise, a single dorsal vein that interconnects the small draining veins from both toes often provides sufficient drainage, but a second backup vein may pay dividends if backflow from the first proves sluggish [54].

Use cruciate incisions on the amputation stumps

A finger amputation stump should always be opened at the distal point with a cruciate incision that creates four equally sized triangular skin flaps

(Fig. 5) [18,55]. This improves the inset of the toe transplant in that its V-shaped flaps can be smoothly interdigitated with the four flaps on the amputation stump [18,55]. Each of these flaps should be undermined to maximize mobility of the flaps over the underlying skeleton and avoid an objectionable bulbous "cobra" deformity at the toe-finger stump junction [55]. Vessels and nerves should also be skeletonized during toe harvest to reduce toe bulkiness and maximize joint motion in the reconstructed finger(s) (see Figs. 2B and 3C, D) [27,55]. This is particularly important when harvesting lesser toe wraparound flaps [27].

Close the donor site primarily and avoid incisions over weight-bearing areas

Skin grafting of the donor site should be avoided whenever possible to lessen foot morbidity [17]. The following approach almost always allows tension-free primary donor site closure, even for combined two-toe harvests [32,40,55]. Dorsal and plantar flaps are designed as distally based "V" shapes with their vertices placed 10 mm proximal to the planned osteotomy level. Most importantly, the distal points of the "V" should be placed at the midpoints of the web spaces adjacent to the harvested toe(s). The dorsal incision can then be extended from the "V" vertex in the form of a lazy "S" over a dominant dorsal pedicle or vertically on the plantar surface for a plantar pedicle while avoiding weight-bearing areas. Toe pulp, hemipulp, and neurosensory first-web flap donor sites are more acceptably covered with split-thickness skin grafts, but these must be performed perfectly to minimize the time to wound healing, foot recovery, and normal walking [27].

Fig. 4. Retrograde dissection of toe vascular pedicles starting in the first web space. (A) Retrograde dissection of the dominant FDMA. (B) Retrograde dissection of the dominant FPMA.
Fig. 5. The cruciate incision produces four equal triangular flaps on the finger amputation stump.

It is not necessary to repair the intermetatarsal ligaments) or place drains into the donor site.

Use intraosseous wiring to obtain stable internal fixation of the transplanted toe

If parallel intraosseous wiring is used, only 5 mm of cortical bone on either side of the osteosynthesis between the toe and amputation stump is required to gain stable bony fixation [56]. Periosteal dissections need only expose the fixation sites. The corresponding bone ends should be cut to enhance the stability of fixation and increase contact area, which are essential for good bone union (see Fig. 3E). Using this simple technique, 98.5% of transplanted toes gained stable union after a mean follow-up of 30 months [56]. This construct is stable enough to allow early rehabilitative mobilization. One important factor is that bony fixation with parallel intraosseous wiring is not rigid, and thus allows postoperative refining adjustments (with splintage) to the malrotation or malalignment of the transplanted toe [56]. This is particularly helpful for refining the prehensile positioning after multiple simultaneous toe transplantations.

Measures to avoid flexion deformities in transplanted toes

The order and technique of tendon repairs and appropriate use of internal fixation and splints are the most important measures that help to avoid clawing of the transplanted toe. The extensor tendon repair should be performed in maximal tension, immediately after bony fixation and before proceeding to the flexor tendon, by passing the long toe extensor tendon through two longitudinal incisions in the recipient extensor tendon and suturing with nylon [12,19,55]. Tension from the flexor tendon repair, which should be performed with the long toe flexor sutured to the flexor digitorum profundus or superficialis tendon as indicated by the level of reconstruction, should reinstate the normal neutral digital cascade. Flexor tendon repair in proximal amputations should be performed in zone III and only for the flexor digitorum profundus so as to avoid subsequent entrapment of the tendon juncture beneath the pulleys during tendon excursion [27]. A Kirschner wire should then be driven across the distal and proximal interphalangeal joints in full extension [12,19,55]. The Kirschner wire should be withdrawn from the proximal interpha-langeal joint at approximately 2 to 4 weeks and

Table 4

Motor rehabilitation after toe-to-hand transplantation

Table 4

Motor rehabilitation after toe-to-hand transplantation

Stage

Timing

Principle aims

Protective

Days 1 to 3

Establish an early rapport with the patient, and provide psychologic support

Early mobilization

Day 4 to week 2

Gentle passive motion of transplanted joints by 15° (protect toe vascularity)

Weeks 2 to 4

Commence full ROM exercises of the joint immediately distal to the osteotomy with wrist kept in neutral position

Weeks 3 and 4

Near-full ROM exercises of the joints proximal to the osteotomy (avoid full ROM so as not to interfere with bony union)

Active mobilization

Weeks 5 and 6

Commence active ROM exercises; blocking flexion/extension exercises begin when tendons are healed

ADL training

Weeks 7 and 8

Tailor rehabilitation to the patient's daily and occupational task requirements to strengthen power and improve joint ROM

Prevocational training

Week 8 onward

Improve power and coordination according to vocational requirements

from the distal interphalangeal joint 2 weeks thereafter. Continued prevention of clawing should be provided by night splints that position the finger into maximal extension for at least 1 year [12,19,55].

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