Anatomy, physiology, and functional restoration of the thumb.

The essential prehensile nature of the human hand rests on the presence of a mobile, sensate thumb with adequate stability and length. The true significance of the thumb-to-hand function is variable and dependent on a person's vocation, expectations, and needs. The frequently stated opinion that the thumb represents 40% of hand function is too exacting and does not allow for flexibility in evaluating a patient's requirements after thumb injury or loss. It is our approach to consider each patient's specific needs for individualized planning of thumb reconstruction. The patient can often offer useful information regarding need for strength vs. precision, width of hand vs. requirements for fine motor function, and concern for the aesthetic nature of an abnormal thumb vs. the variable deformities resultant from thumb reconstruction. We offer a review of the basic anatomy and physiology of the human thumb, with emphasis on hand-and-thumb function. We present the alternatives for thumb reconstruction, the advantages and disadvantages, and the relationships to a specific patient's needs. Clinical examples of various methods of thumb reconstruction, including metacarpal lengthening, phalangization, osteoplastic reconstruction, pollicization, and toe-to-hand transfer are provided.