Surgical technique

Toe-to-hand transfers are ideally performed with a two-team approach. One team identifies the recipient structures in the hand while the other team simultaneously harvests the toe. Both the hand dissection and foot dissection are performed under tourniquet control. The anatomy of the hand varies depending on the congenital anomaly. In general, aplastic conditions have small sometimes absent structures, whereas the anatomy proximal to a congenital constriction ring is normal. The hand should be dissected first to ensure that recipient nerves and tendons are available in the hand. The limiting factor for toe transfer will likely be the adequacy of the recipient vessels in the hand or wrist. If a more suitable artery or vein is found in the distal forearm, vein grafting may be required to span the distance between the toe vessels and recipient vessels.

The toe is harvested via triangular skin flaps extending from the base of the toe on the dorsal and plantar surface of the foot (see Fig. 1C). The incision is extended proximally and dorsally over the dorsalis pedis artery. The venous drainage to the great or second toe is isolated and dissected proximally to a large branch of the greater saphe-nous vein at the level of the ankle. The arterial pedicle to the toe transfer may be dissected in two ways—either proximal-to-distal or distal-to-proximal. The dorsalis pedis artery can be identified proximally and traced distally into the first dorsal metatarsal artery (FDMA) and its branches to the great toe or second toe preserved, depending on which toe is to be harvested. There are great variations in the arterial supply to the toes [38]. Ideally, the FDMA will be found superficially, although it may lie within the interosseous muscle or intramuscularly. When the FDMA is small or absent, the first plantar metatarsal artery (FPMA) has to be used, which requires a plantar approach. An acceptable FDMA has been shown to be present in 66% of cases, whereas the FPMA is present in 34% of cases [13]. The success of

Symbrachydactyly Thumb

Fig. 4. (A-C) Two-year-old girl with symbrachydactyly of her right hand with a thumb but absent index, middle, and ring fingers and a hypoplastic small finger. (D, E) She underwent a right second toe transfer at age 2 years into the small finger position. (F-I) Two years postoperatively, she has excellent pinch and grasp function with her right hand.

Fig. 4. (A-C) Two-year-old girl with symbrachydactyly of her right hand with a thumb but absent index, middle, and ring fingers and a hypoplastic small finger. (D, E) She underwent a right second toe transfer at age 2 years into the small finger position. (F-I) Two years postoperatively, she has excellent pinch and grasp function with her right hand.

toe-to-hand transfer is related not to the anatomic location of the vessel but to the diameter, which ideally should be 1 mm or more [39]. An alternative approach is to start the dissection distally over the dorsum of the great toe-second toe web space. If the FDMA appears suitable, it is dissected in a distal-to-proximal direction. If the FDMA is not suitable or absent, the FPMA is chosen [40].

The extensor tendons of the toe are dissected in a distal-to-proximal direction. Dissection is then continued plantarly into the web space to identify the digital nerves which are smaller and shorter compared with those in the hand [10]. To gain length, it is necessary to separate the common digital nerves by intraneural dissection in the first and second web spaces. In addition to the plantar digital nerves, the deep peroneal nerve can often be found and included in the harvest. The transverse intermetacarpal ligaments are then divided to facilitate more proximal dissection to isolate the flexor digitorum longus and brevis tendons proximal to the tendon sheath. Before division of any tendons, it is important to ascertain the length needed in the hand. The bone level at which the toe is harvested depends on what is required in the hand; therefore, the osteotomy may be at the metatarsal, metatarsophalangeal joint, or proximal phalangeal level.

After dissection of the toe is completed and before transfer to the hand, the tourniquet is released and the toe re-perfused, isolated only on a single artery and vein. After the arterial and venous pedicles have been ligated and divided and the toe transferred, the foot incision is closed primarily, and a posterior splint is applied. occasionally, the second metatarsal requires additional shortening to adequately close the incision. When the great toe is harvested, split-thickness skin grafts may be required for closure.

After transfer to the hand, the toe is positioned anatomically and the correct length determined. Excess metacarpal is removed with an oscillating saw. When the toe is transferred into the thumb position, the toe is pronated 120 degrees, but this can be modified based on the position of the remaining fingers. Bony fixation is achieved using plates and screws, K-wires, or interosseous wiring between the toe metatarsal and the bony foundation in the hand. The authors routinely use 90-90 interosseous wiring. The epiphyseal growth plates must be protected. Following this, the extensor and flexor tendons are repaired. In children with aplastic hands, tendon transfers to the thumb may be required if the normal anatomic structures are not available. An opposition tendon transfer may be performed as a primary or secondary procedure [41]. The recipient vessels for microvascular anastomoses depend on the patient's anatomy and suitable size match. Monofilament 10-0 nylon suture is used for vessel anastomoses and the nerve coaptations. Recipient vessels include the radial and ulnar arteries and superficial palmar arch. The vascular anastomoses are usually performed in an end-to-end fashion, although, occasionally, the arterial anastomosis is done in an end-to-side fashion.

simultaneous double second toe transfers are occasionally performed if the appropriate surgical teams are available. When an abnormal toe is transferred out of necessity, such as in a child with bilateral cleft hands and feet, correction of alignment of the abnormal toe is carried out at a second stage. If a lower extremity amputation is indicated, toe transfers may be accomplished at the same time [42,43].

The arm and leg are wrapped in large bulky splints for protection. The toe transfer is left partially exposed for clinical observation. The patient is maintained on intravenous dextran until postoperative day 5 and then weaned. Aspirin is continued for an additional 1 month. The patient is usually discharged by postoperative day 7. The parents are instructed to keep the splint on the arm and leg clean and dry until the follow-up visit. Clinically, the toe is evaluated for color and capillary refill every hour by the nursing staff. objective monitoring techniques include surface temperature monitoring, tissue pH, transcutaneous PO2, and laser Doppler flowmetry [44]. Invasive monitoring techniques include radioactive isotopes, quantitative fluoroscein, and implant-able Doppler probes. In the authors' patients, toe transfers are monitored with a continuous oxygen saturation probe (pediatric pulse oximeter). Differential pulse oximetry appears to be superior to temperature monitoring and percutaneous and laser Doppler monitoring and provides the most simple and continuous technique of noninvasive monitoring for toe transfers [45]. This method allows rapid detection if thrombosis of the micro-surgical anastomoses occurs. The opportunity to salvage a toe transfer after vascular compromise is determined by the time at which the problem is detected. A delay in diagnosis may result in a toe transfer that is not salvageable.

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