Reconstruction of metacarpal hands

The so-called ''metacarpal hand'' results when all its fingers been amputated proximal to the middle of the proximal phalanx, with (type II) or without (type I) thumb involvement [28,29,34]. Type I metacarpal hands can be further classified into subtypes IA, IB, and IC depending on the level of amputation, and type II metacarpal hands can be further classified into subtypes IIA, IIB, IIC, and IID depending on the adequacy of thenar muscular function and the condition of the basal joint (Tables 2 and 3) [28,29]. Type I and type II injuries should have at least two adjacent fingers reconstructed for the reasons described previously (Fig. 3). Whether the toe transplantations are combined or separate should be determined by whether the amputation level is distal (warranting separate toe harvests) or proximal (warranting combined toe harvest) to the web space. For subtypes IIA and IIB in which thenar muscular function is adequate, simultaneous reconstruction of the fingers and thumb is recommended to shorten the duration of disability [27-29]. In subtypes IIC and IID, the fingers should be reconstructed first and a temporary thumb post provided to assist in the accurate determination of toe length and position required for reconstructing the thumb during a second-stage toe transplantation procedure [27-29]. When the thumb carpometacarpal joint is damaged (subtype IID), the reconstructed

Table 2

Subclassification of type I metacarpal hands and recommended reconstructive techniques of toe transplantation

Table 2

Subclassification of type I metacarpal hands and recommended reconstructive techniques of toe transplantation

Finger amputation

Reconstructive

Subtype

level

recommendations

IA

Distal to MCPJ

Bilateral second toes for amputations distal to the web space Combined second and third toes for amputations proximal to the web space (trans-proximal phalan-geal transfer)

IB

Through MCPJ

Combined second

Metacarpal

and third toes

articular surface

(including

intact

composite joint transfer)

IC

Through MCPJ

Combined second

Metacarpal

and third toes

articular surface

(transmetatarsal

damaged or

transfer)

absent

Subclassification of type II metacarpal hands and recommended reconstructive techniques of toe transplantation

Table 3

Subclassification of type II metacarpal hands and recommended reconstructive techniques of toe transplantation

Thumb amputation

Reconstructive

Subtype

level

recommendations

IIA

Distal to metacarpal

Whole or trimmed

neck

great toe transfer

(transproximal

phalangeal

transfer)

IIB

Proximal to

Preliminary

metacarpal neck

distraction length-

Thenar function

ening or interpo-

adequate

sitional bone graft

followed by

whole or trimmed

great toe transfer

Alternatively,

transmetatarsal

second toe

transfer

IIC

Any level with

Thumb

inadequate thenar

reconstruction

function

should occur at

a second stage

after finger

reconstruction

Tendon transfer

should restore

opposition.

IID

Any level with

Same as for IIA and

damaged CMC

IIB except an

joint

immobile thumb

post should be

reconstructed

instead

Abbreviation: CMC, carpometacarpal.

Abbreviation: CMC, carpometacarpal.

thumb should serve as an immobile post against the reconstructed fingers [27-29].

Most complex are the bilateral metacarpal hand injuries. Both feet are required to donate toes if an optimal bilateral reconstruction is to be achieved. A careful account of the patient's required grip types and function is essential; however, the following strategy provides good bilateral outcomes that satisfy most patients' functional demands with acceptable donor site morbidity in the feet. Restoration of the dominant thumb and its two adjacent radial fingers provides unilateral tripod pinch and chuck grip and can be achieved by simultaneous (if thenar function is adequate) transplantation of the left great toe, optimally harvested in a trimmed-toe fashion, and the contralateral combined second and third toes

Fig. 3. Reconstruction of a type IC metacarpal hand injury using a second toe and combined second and third toe transplant. (A) Metacarpal hand type IC injury. (B) Pedicled groin flap. (C) Left combined second and third toe transplant harvested. (D) Right single second toe transplant harvested. (E) Intraosseous wiring of prepared bone ends in the hand. (F) Good prehensile function. (G) Acceptable donor site appearance and morbidity.

Fig. 3. Reconstruction of a type IC metacarpal hand injury using a second toe and combined second and third toe transplant. (A) Metacarpal hand type IC injury. (B) Pedicled groin flap. (C) Left combined second and third toe transplant harvested. (D) Right single second toe transplant harvested. (E) Intraosseous wiring of prepared bone ends in the hand. (F) Good prehensile function. (G) Acceptable donor site appearance and morbidity.

based on a single pedicle [28,32,35]. The nondominant thumb and one of the radial fingers can be reconstructed with the individual third toe and individual fourth toe from the left foot to achieve pulp-to-pulp pinch, thus preserving the left second toe to maintain optimal foot function [28].

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