The Case for Salvaging a Hypoplastic Thumb Over Pollicization

By William Seitz, Jr., MD

Pollicization of the index finger, to create an opposable digit in the relative position of a thumb, can be a very functional surgical procedure. It also can be used to create a thumb-like appendage when a child is born without a thumb. It is likewise useful if a child is born with a hypoplastic (underdeveloped) thumb, sometimes called a pouce flottant (floating thumb).

Blauth has classified the hypoplastic thumb into five grades:

• In grades 1 and 2, skeletal components of a normal thumb are present but small, the first web space is contracted, frequently some of the normal thumb musculature is absent and the existing thumb is usually salvageable.

• Grade 3 represents a gray zone in which only a portion of the thumb metacarpal is present, the phalanges are small and usually extrinsic motors are deficient. It is these grade 3 deficiencies that not uncommonly are discarded in preference of an attempted pollicization of the index finger (which frequently requires secondary fine-tuning procedures for optimal function of the pollicized index finger).

• In grade 4 deficiency, there is a small, narrow stalk without any metacarpal remnant.

• Grade 5 represents complete absence of the thumb.

Focus on Grade 3 Deficiencies

We have focused on grade 3 deficiencies, recognizing that in many cases a functional thumb can be salvaged through staged reconstruction using a number of the techniques we have developed and enhanced at Cleveland Clinic.1-8 When there is a healthy nonconstricted skin bridge between the palm and the rudimentary thumb, with good sensation and circulation, staged reconstruction can be performed successfully, including:

• Transplantation of free nonvascularized toe phalanges to create a stable post articulating with the adjacent radial most carpal bone

• Secondary distraction lengthening as needed to enhance appropriate functional length of the thumb

• Combined web space deepening and muscle and tendon transfers using the extensor indicis proprius to substitute for the extensor pollicis longus, the flexor digitorum sublimis of the ring finger to substitute for the flexor pollicis longus, and the abductor digiti minimi subcutaneous palmar transfer for opponensplasty.

Three Decades of Thumb Salvage

We have refined these techniques over nearly 30 years of experience in congenital hand surgery for creating digits in the hands of patients born without normal fingers, and they have proven to be extremely effective in providing an opposing, prehensile thumb. Our procedure has provided a functional alternative to ablation of a hypoplastic but otherwise viable thumb as opposed to amputation and pollicization. The techniques of toe phalangeal transfer, distraction neoosteogenesis lengthening and restoration of function have been delineated in our peer-reviewed publications.1-8

Figure 1. (A) A very hypoplastic (grade 3B) thumb that might even be termed a pouce flottant is seen in a newborn whose parents were told the only option was amputation and pollicization of the index finger. (B) Two free toe phalanges are transferred to provide supportive bone stock. (C) The distraction lengthening apparatus has been applied to lengthen the thumb to satisfactory length and alignment in an opposed position. (D) During the lengthening procedure, the child is already learning to use his thumb in a prehensile manner. (See Figure 3 for follow-up images of this patient.)

References

1. Seitz WH Jr. Distraction lengthening in the hand and upper extremity. In: Green DP, ed. Operative Hand Surgery. 6th ed. New York: Churchill Livingstone; 2010:1483-1502.

2. Seitz WH Jr, Shimko P, Patterson RW. Long-term results of callus distraction lengthening in the hand and upper extremity for traumatic and congenital deficiencies. J Bone Joint Surg Am. 2010;92(suppl 2):47-58.

3. Patterson RW, Seitz WH Jr. Nonvascularized toe phalangeal transfer and distraction lengthening for symbrachydactyly. J Hand Surg Am. 2010;35(4):652-658.

4. Seitz WH Jr, Bley L. Distraction lengthening in the hand using the principle of callotasis. In: Raskin KB, ed. Atlas of the Hand Clinics. Philadelphia: WB Saunders; 2000:31-39.

5. Seitz WH Jr, Paley D. Osteogenesis lengthening for congenital reconstruction in the hand and forearm. In: Buck-Gramcko D, ed. Congenital Malformations of the Hand and Forearm. New York: Churchill Livingstone; 1998:119-128.

6. Seitz WH Jr, Froimson AI. Digital lengthening using the callotasis technique. Orthopedics. 1995;18(2):129-138.

7. Seitz WH Jr, Dobyns JH. Digital lengthening with emphasis on distraction osteogenesis in the upper limb. Hand Clin. 1993;9(4):699-706.

8. Seitz WH Jr, Froimson AI. Callotasis lengthening in the upper extremity: indications, techniques, and pitfalls. J Hand Surg Am. 1991;16(5):932-939.

Dr. Seitz is an upper extremity specialist in the Department of Orthopaedic Surgery and Professor of Orthopaedic Surgery at Cleveland Clinic Lerner College of Medicine of Case Western Reserve University. He has a special interest in reconstruction of congenital hand deformities. He can be reached at 216.363.2370 or seitzw@ccf.org.