Toe-to-Hand Transfer

What was Nicoladoni’s contribution to thumb reconstruction?

Carl Nicoladoni (1847–1902), a pioneering Austrian surgeon, was the first to perform the pedicled second toe-to-hand transfer for amputated thumb reconstruction. His description was published in 1900.

On whose experimental work was the first human microvascular great toe-to-hand transfer based?

Buncke. In 1966, Buncke et al. published their account of successful toe-to-hand microvascular transfer in rhesus monkeys. This work itself was inspired by Nicoladoni’s concept of toe-to-hand transfer first performed at the end of the 19th century.

Who performed the first microvascular second toe-to-hand transfer in humans?

Yang Dongyue of Shanghai First Medical University in China performed the world’s first successful microvascular toe-to-hand transfer, utilizing the second toe, in 1967.

When were toe transplantations first used for reconstruction of congenital hand differences?

In the late 1970s, when O’Brien and colleagues pioneered thumb reconstruction in children with congenital hand differences using microsurgical technique. These applications were popularized by Gilbert and others in the 1980s.

Which two arterial pedicles may supply great toe or second toe transfers?

The first dorsal metatarsal artery (FDMA) and the first plantar metatarsal artery (FPMA). The FDMA is dominant in 70% of cases, FPMA in 20%, and both are of equal caliber in 10% cases.

Where in the foot is the FDMA located?

The FDMA lies between the first and second metatarsals, at varying depths from superficial to the interosseous muscle to intramuscular to a position plantar to the interosseous muscle. The FDMA passes dorsal to the deep transverse metatarsal ligament, which connects the plantar plates of the metatarsophalangeal (MTP) joints.

Is there a classification system to describe the various positions of the FDMA?

There are at least three classification systems but it is not necessary to learn them. By commencing the dissection of the toe’s vascular pedicle in the web space (instead of on the dorsum of the foot), the pedicle can be revealed retrograde and its pathway followed along whatever direction it takes.

Are the dorsal metatarsal and plantar metatarsal arterial systems connected?

Yes: first, by the communicating vessels, which pass between the first and second metatarsals; second, the two systems converge at the first web space.

Which digital artery of the toe is more important, the dorsal or plantar system?

The plantar digital artery. The dorsal digital artery is only rarely present.

What venous system should be used to drain a great toe or second toe transfer?

The intermediate level veins, which give rise to the greater saphenous vein.

Which nerve supplies sensation to the first web space?

The deep peroneal nerve.

Which nerves are the most important for sensation of the transferred toe?

The medial and lateral proper plantar digital nerves, which are terminal branches of the medial plantar nerve. The digital nerves are located plantar to the plantar digital arteries.

Which tendon is cut when dissecting the FDMA on the foot dorsum?

Extensor hallucis brevis.

In which types of congenital hand conditions should a toe-to-hand transfer be considered?

Constriction band syndrome, hands with no fingers but an adequate thumb, and thumb absence with a complex hand malformation. The latter two situations often have absent or anomalous recipient structures. A well-thought-out operative plan with alternative recipient vessels, nerves, and tendons must be devised. Pollicization should be considered for isolated thumb aplasia/significant hypoplasia and can offer better outcomes. For all these patients a thorough cardiorespiratory/anesthetic workup is mandatory as coexisting systems anomalies are not uncommon.

How do outcomes differ between index finger pollicization and microsurgical second toe transfer for hypoplastic thumb reconstruction in children with radial deficiency?

Tan and Tu compared a total of 30 children reconstructed with one of these two methods. They reported that patients who had undergone pollicization had earlier motor and sensory recovery and better range of motion. Patients who received toe transfers had higher parental satisfaction and performed better in some activities of daily living.

In patients who may be future candidates for toe-to-hand transfer, which structures should be preserved during the initial emergent treatment? Why?

Skin: Toe transfers have a paucity of skin; local flaps further injure and ultimately scar the hand, making recipient-site preparation more difficult; free flaps for skin coverage use all-important recipient vessels.

Joints: Intact proximal interphalangeal or metacarpophalangeal (MCP) joints will enhance mobility and function following transfer; preservation of only the proximal articular surface of the MCP joint is better than saving no articular surface because a composite joint reconstruction is possible.

Bone: Adequate bony length allows restoration of digital length with toe transfer, which improves appearance and function; the great toe should not be harvested proximal to the MTP joint, necessitating a staged reconstruction or second toe transfer if the thumb is excessively shortened.

Tendons: Maintaining flexor tendon length ensures preservation of the flexor pulley system; the complex extensor mechanism should be saved as it is difficult to reconstruct; less donor-site morbidity is incurred if tendons are preserved in the hand.

Vessels: Damage to recipient vessels either precludes transfer or necessitates riskier vein grafting.

Nerve: Preserving nerve length reduces donor-site dissection; a more distal nerve repair during transfer will speed up sensory recovery.

How can closure of wounds in potential toe-to-hand candidates be achieved?

Pedicled distant flaps (such as the pedicled groin flap) can import liberal fresh uninjured tissues and do not sacrifice local tissues or vessels.

Should arteriography of the foot be performed prior to surgery?

Preoperative arteriography is not required unless the donor foot has been injured or is congenitally anomalous or if the patient has significant peripheral vascular disease. The vascular pedicle is dissected in a retrograde manner, thus it is not necessary to know its proximal course.

How does one increase pedicle length when harvesting a first plantar metatarsal artery dominant toe?

The first plantar metatarsal artery is dominant in approximately 20% of patients. Its dissection is reasonably straightforward until the deep perforator is reached, which communicates between the plantar and dorsal systems. While it is feasible to trace the pedicle retrograde between the metatarsals, it is actually safer and more expedient to terminate the dissection at this point and extend the pedicle with vein grafts as necessary.

Which pedicle should be chosen when neither the first plantar nor the first dorsal metatarsal artery is dominant in the web space?

When the plantar and dorsal systems are codominant (which is the case in approximately 10% of cases), one should choose the dorsal system because it is easier to dissect and provides a lengthier pedicle.

How should one extend the incision on the plantar and the dorsal feet when harvesting a toe?

For a plantar system–dominant harvest, the incision should be extended in a straight line away from the weight-bearing surfaces. For a dorsal system–dominant harvest, the incision should be extended as a lazy-S incision.

What risk factors predispose to vascular compromise requiring re-exploration of single-toe transplants?

Multivariate analyses revealed that postoperative wound infection, metacarpal hand injuries, and preceding flap coverage were independently associated with re-exploration for vascular compromise.

What are the most common causes of vascular compromise found at re-exploration of single-toe transplants?

The most common causes for vascular compromise in single-toe transplants necessitating re-exploration are: arterial spasm (61%), arterial thrombosis (42%), and venous thrombosis (25%); more than one factor can be found at any one re-exploration.

What type of secondary procedures might be necessary for patients who undergo toe-to-hand transfer?

Approximately 14% of patients require surgical revisions to improve function including: flexor tendon tenolysis (7%), arthrodesis (2%), web space deepening (2%), osteotomy for malunion (2%), or bone grafting for nonunion. Some patients also request aesthetic improvement.

What techniques are available to improve the cosmetic outcome of toe transplantation?

Pulp plasty improves the appearance of the toe transplant but also may be indicated if the distal pulp is too bulky or needs improved stability. In addition, patients who have had trimmed toe or modified wraparound transfer may request osteotomy of the remaining tubercle (on the side of the skeleton that was not trimmed at the primary transfer) to remove the “swelling” on the fibular side of the interphalangeal joint of the neo-digit. Recently, Ju and Hou described a pulp transposition flap that simultaneously reduces pulp bulk whilst augmenting the waist of the second toe at time of transplantation to smoothen the contour of the reconstructed digit. Procedures to improve nail cosmesis are addressed in the following question.

Describe a method to reduce the toenail (of the neo-thumb) to match that of the opposite normal thumb nail.

Narrowing the toenail by excluding a portion of its tibial half from the transfer is probably the simplest and most widely practiced technique of improving nail symmetry compared to the unoperated contralateral thumb. However, this method risks nail growth and damages the specialized paronychial and eponychial contours to create an unnaturally straight edge to the nail plate. A method to create a near-normal and symmetric nail on the neo-thumb is perhaps the most significant remaining obstacle to a truly aesthetic thumb reconstruction.

How many motor units power the thumb?

Nine: four extrinsic muscles and five intrinsic muscles.

In which important way does the motion of the great-toe MTP joint differ from the thumb MCP joint?

The MTP range is one of hyperextension rather than flexion.

What is the two-point discrimination of the great-toe in situ? Following transplantation and rehabilitation, is the sensation in the transplanted toe better or worse than before transfer?

The great toe in situ has an average static two-point discrimination of 10 mm (2× standard deviation = ± 6 mm). Following transfer sensation varies considerably. Mean static two-point discrimination of 6.5 mm may be achieved in patients with optimal nerve coaptation and adequate sensory reeducation.

What proportion of hand function does the thumb represent?

40% to 50% of global hand function.

What types of thumb to finger pinches are commonly discussed when analyzing prehensile function?

Pulp-to-pulp, lateral (key), and chuck three-point (tripod) pinch. In addition the thumb assists the hand in power (cylinder) grasp. Hook grip requires only fingers. Without any digits present the hand may function as a bat.

Any preoperative planning methods to decide the optimal position of the toe transplant for thumb reconstruction?

Use of a prosthetic thumb by the patient can help determine the exact position of the future transplanted toe and for planning additional procedures, such as opponensplasties. Otherwise, careful preoperative discussion and analysis with the patient regarding prehension types and requirements, including at work, are important to this decision.

What are the most common etiologies of a thumb absence/dysfunction that require reconstruction?

Traumatic amputation, postoncologic resection, and certain types of congenital thumb differences.

What is the best surgical procedure to treat an acutely amputated thumb?

Replantation.

If replantation is not possible, is primary toe-to-hand transfer possible?

Yes. Advantages include decreased time in hospital and earlier return to work. There are no statistically significant differences in the rate of early postoperative complications between the primary and secondary transfers. However, subjectively, patients with primary reconstructions are less satisfied with the function and appearance of the reconstructed digit than patients who have lived for some time with the amputation. Primary toe-to-hand transfer must therefore be carefully and thoroughly discussed so that the patient has a realistic expectation of outcome; secondary reconstruction should be strongly considered if there is any doubt in the level of the patient’s expectations.

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