Clin Orthop Surg.  2012 Mar;4(1):1-17. 10.4055/cios.2012.4.1.1.

Thumb Duplication: Concepts and Techniques

• Tonkin MA

• KMID: 1245395
• DOI: http://doi.org/10.4055/cios.2012.4.1.1

Abstract

Within the Oberg, Manske, Tonkin (OMT) classification, thumb duplications are a failure of formation and/or differentiation affecting the radial-ulnar axis of the hand plate. The Wassel description of seven types of thumb duplication provides a good structure from which an approach to management is based. The aim of surgical reconstruction is to obtain a stable, mobile thumb of adequate size and appropriate shape. The most common form of reconstruction is removal of the lesser digit and reconstruction of the dominant digit. Surgical techniques address the problems of deviation, instability and lack of size. The disadvantages of the Bilhaut-Cloquet procedure, these being joint stiffness and a nail ridge, may be lesser concerns when reconstruction of one digit will not create a satisfactory thumb of adequate mobility, stability, alignment and size. Complicated problems of triphalangism, triplication, ulnar dimelia and the rare circumstance in which neither of the duplicated thumbs may be adequately reconstructed present specific challenges which demand alternative techniques.

Keyword

Thumb duplication; Classification; Assessment; Reconstruction

MeSH Terms

Hand Deformities, Congenital/classification/*surgery
Humans
Orthopedic Procedures/*methods
Patient Care Planning
*Reconstructive Surgical Procedures
Thumb/*abnormalities/*surgery

Figure

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  Fig. 1 The Wassel classification of thumb duplication. Reprinted with permission from Springer-Verlag.3)

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  Fig. 2 Appearance of the dominant thumb when the examiner's hand conceals the radial duplicate.

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  Fig. 3 Elevation of a neurovascular island flap from the radial aspect of the radial thumb to improve the contour of the reconstructed thumb.

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  Fig. 4 Wassel type IV thumb duplication with divergence of proximal phalanges and convergence of distal phalanges.

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  Fig. 5 Diagram of capsular-periosteal flap for metacarpophalangeal joint radial collateral ligament reconstruction; and longitudinal osteotomy to remove redundant articular surface of the metacarpal head.

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  Fig. 6 Distal bifurcation of the flexor pollicis longus with eccentric insertions into the terminal phalanges.

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  Fig. 7 Connections between the flexor pollicis longus (white arrow) and the extrinsic extensors (black arrow).

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  Fig. 8 Corrective osteotomies at the neck of the proximal phalanx (white arrow) and the neck of the metacarpal (black arrow).

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  Fig. 9 Tendon realignment and pulley reconstruction.

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  Fig. 10 Reconstruction of the metacarpophalangeal joint radial collateral ligament with a capsular-periosteal flap. Soft tissue from the base of the proximal phalanx is sutured to the metacarpal neck (white arrow). Radial collateral ligament and thenar musculature is oversewn into the ligament reconstruction (black arrow).

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  Fig. 11 The "elephant trunk" sign of global metacarpophalangeal joint instability.

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  Fig. 12 Preoperative and postoperative views of a Wassel type I with equal size and shape of duplicate parts.

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  Fig. 13 Diagram of excision of triangular fragments of bone and cartilage from the proximal phalangeal head to decompress the terminal phalangeal reconstruction.

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  Fig. 14 (A) Inability to appose the two parts of the terminal phalanx along their whole length. (B) Removal of triangular wedge of cartilage and bone from the proximal phalangeal head bilaterally. (C) Easy apposition of terminal phalangeal components.

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  Fig. 15 Two fine interosseous wires are placed at defined distances distal to the physes.

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  Fig. 16 Significant instability and deviation of a type III thumb duplication.

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  Fig. 17 Bilhaut-Cloquet reconstruction of a type IV thumb duplication with good carpometacarpal and metacarpophalangeal joint motion, restricted interphalangeal joint motion, good size and appearance and minimal ridging.

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  Fig. 18 Modified Bilhaut-Cloquet procedure.

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  Fig. 19 Preoperative appearance prior to combination of acral transposition of the distal part of the ulnar thumb to the radial thumb with shortening and fusions.

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  Fig. 20 Postoperative result from the case shown in Fig. 19.

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  Fig. 21 Preoperative appearance and X-ray of a thumb duplication.

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  Fig. 22 Postoperative appearance and X-ray following pollicisation of the dominant digit in the case shown in Fig. 21.

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  Fig. 23 Shortening, rotational metacarpal osteotomy and interphalangeal fusion with first web reconstruction of the optimal digit in a case of bilateral thumb triplication.

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  Fig. 24 Postoperative appearance from the case shown in Fig. 23.

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  Fig. 25 Pre- and postoperative appearance in a case of ulnar dimelia in which optimal appearance and function were obtained by reducing the number of digits to four.

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