Our thumbs are amazing. Their independent movement allows them to swing away from the palm and face (oppose) the other fingers. Our thumbs contribute to everything man-made. Various languages celebrate its function. Shastin Farsi means both 60 and thumb, signifying that it constitutes 60% of the hand’s function. In Turkish, thumb is bas parmak—chief finger. And in Latin it is pollex, which is derived from pollere—to be strong. Isaac Newton marveled, “In the absence of any other proof, the thumb alone would convince me of God’s existence.”
Because this wonderful digit sticks out somewhat awkwardly and is involved in nearly every manual activity, it is at high risk for injury. Anybody with a severely injured thumb immediately appreciates the complexity of civilization and the difficulties of thumbless participation. In case of loss of another single digit, the three remaining can pretty well do the work of four. Loss of the thumb, with its unique ability to oppose the other digits, has devastating consequences. Understanding its importance, hand surgeons work all night if necessary to piece an injured thumb back together. At times a completely amputated thumb can be successfully replanted. Although a replanted thumb is never normal in its sensibility, motion, and strength, it is usually good enough to allow the owner to rejoin the human race.
There are three major reconstruction techniques available when surgeons cannot repair or replant this critical part. I call them Beg, Borrow, and Steal.
For the first reconstruction technique, the surgeon and patient persuade (beg) the thumb stump to lengthen. Steel pins are placed across the residual bone and attached to an expandable, steel frame. The bone is cut between the pins. Then by turning a little knob, the patient expands the frame in nearly microscopic increments on an hourly basis over several months. The bone and the surrounding muscles, tendons, nerves, and skin hardly know they are being stretched. They just think there is some powerful growing under way, and they rally to keep up.
After several months in “the rack,” the thumb is back to nearly its normal length. A bone graft from the pelvic rim fills in the gap. The advantage of this lengthening procedure is that it avoids borrowing or stealing other digits. Its disadvantages are that it does not restore the thumbnail or any missing joints.
Next week: Thumb Reconstruction II: Borrowing
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