The great toe is ideally suited in size and shape to replace the missing thumb while preserving breadth of the palm and restoring a strong opposable pinch and grasp. The flexibility of the interphalangeal joint that often increases when the toe is transplanted to the hand is important in providing the pincer effect necessary when the hand is used to pick up large and heavy objects. Although somewhat wider than the thumb, the transplanted great toe decreases in size up to one third when transplanted to the hand, possibly because of denervation or altered function.

Because the thumb length is so important, at least a third of the metacarpal bone must be present before great-toe transplantation can be considered. When the articular surface of the distal end of the metacarpal is present, a compound joint can be constructed, using the articular surface of the proximal phalanx of the great toe with a cuff of joint capsule to reconstruct a metacarpophalangeal joint. Such joints add greatly to the mobility and dexterity of the transplanted toe. If a nubbin or portion of the proximal phalanx of the thumb remains, even though the metacarpal joint may be stiff, it is often worthwhile to use this phalangeal remnant as an intramedullary peg into the base of the toe transplant. With the increased leverage of the transplanted toe, the stiff metacarpal joint can often be satisfactorily mobilized. Amputations at the distal phalangeal joint level are less amenable to reconstruction by great-toe transplant because the circumference of the distal toe is considerably larger than the distal phalanx of the thumb. The size discrepancy can be corrected at the time of surgery using the modified wrap-around technique described for total thumb reconstruction.10 In this instance, the distal phalanx is thinned and narrowed at the time of transfer.11 If the second toe is large, it can be used to replace the distal portion of the thumb, although this produces a "salt shaker" appearance in the thumb. Other techniques of thumb lengthening might be considered at this level, using bone distraction and metacarpal lengthening, or deepening the first web space.

Technical Considerations

The most important technical consideration in planning a great-toe transplant is the residual blood supply in th injured hand and the anatomy of the vascular supply in the foot. Arteriograms are indicated when any degree of injury exists in the hand and are often helpful in the foot, although high-quality films are sometimes difficult to obtain because vascular spasm in the lower extremity is difficult to overcome and requires the concerted effort of the radiology staff to obtain good peripheral vascular detail. Best results are obtained when the procedure is performed under general anesthesia, which is the method of choice in children. Arteriograms are not done in most children when the area of trauma is minimal.

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