589046
research-article2015
JHS0010.1177/1753193415589046Journal of Hand SurgeryShort report letter
JHS(E)
Short report letter
The Journal of Hand Surgery (European Volume) XXE(X) 1–2 jhs.sagepub.com
The ‘super digit’ revisited Dear Sir, Figure 1 shows the right hand of a 28-month-old boy, with no other physical anomalies and otherwise normal development. The radiograph (Figure 2) shows two metacarpal bones (index and middle) and two well defined proximal phalanges fused at their heads to support a single distal digit. Because of the almost 90° of angulation between the heads of both proximal phalanges, there is significant divergence between the index and middle metacarpal bones. This anomaly is difficult to classify and we regard it as a variant form of ‘super digit’, a term coined by Wood (1990). Since then, the concept has seen little development. In his series of 24 fingers, Wood classified the super digit as type I, composed of two metacarpals supporting a finger, and type II, a single metacarpal that supports two or more digits distally. Type I was sub-classified as: type IA, where two metacarpals support a single, well defined but enlarged digit; type IB, with two digits evolving into one (i.e. an incomplete fusion along the longitudinal axis); type IC, with a large delta proximal phalanx supporting a fairly normal distal digit (type IC1) or two distal digits (type IC2). Type II is divided in four groups: type IIA, a single metacarpal supporting two digits, each with three well defined phalanges; type IIB, with a large (type IIB1) or split (type IIB2) proximal phalanx, supporting two distal digits; type IIC and type IID. Although not clearly defined by Wood, we interpret type IIC as having a single proximal delta phalanx supporting two almost completely fused distal fingers (type IIC1) or two proximal delta phalanges with two fingers with soft tissue syndactyly (type IIC2). Type IID seems to be associated with polysyndactyly, with a single (type IID2) or split or multiple proximal phalanges (type IID1). With 25 years of experience, Wood prudently advised against surgery to try to make two fingers out of a super digit; 14 years later, Dao et al. (2004)
Figure 1. The appearance of the right hand.
Figure 2. Radiograph of the hand.
Downloaded from jhs.sagepub.com at UNIV PRINCE EDWARD ISLAND on September 22, 2015
2
The Journal of Hand Surgery (Eur)
maintained the same opinion. The contraindication for surgery in super digits has been repeated in several textbooks, mainly in chapters on syndactyly, citing Wood’s original article. In fact, Wood cautioned against trying to separate super digits; he did not clearly state an absolute surgical contraindication to every problem, such as angulation, that might occur. Regarding the present case, there is good mobility and dexterity in the right hand, so we see no point in operating, given the current status. However, we do feel that with normal growth of both the metacarpals and proximal phalanges, a situation might occur in which, as a result of metacarpal divergence, the distance between the thumb and the ring and little fingers may affect grip. Then, a possible solution would be to excise the radial proximal phalanx (preserving part of the head) and restore the middle finger anatomy with reconstruction of the collateral ligament, a wedge osteotomy and reconstruction of the transverse metacarpal ligament. The unique characteristics of this case do not fall into Wood’s original classification, since there are two metacarpal bones and two well defined proximal phalanges, fused only at their heads to support a distal digit, and also prominent metacarpal divergence,
not found in type I. If more similar cases are found, perhaps a new category (type III) could be established, bearing in mind that there were only one or at most two examples of each type of anomaly in Wood’s original article. Conflict of interests None declared.
References Dao KD, Shin AY, Billings A, Oberg KC, Wood VE. Surgical treatment of congenital syndactyly of the hand. J Am Acad Orthop Surg. 2004, 12: 39–48. Wood VE. Super digit. Hand Clin. 1990, 6: 673–84.
J. Nunes da Costa and J. Matias, Department of Plastic, Reconstructive and Maxillofacial Surgery, Hospital de Egas Moniz, CHLO, Lisbon, Portugal Corresponding author: [email protected]
© The Author(s) 2015 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav doi: 10.1177/1753193415589046 available online at http://jhs.sagepub.com
Downloaded from jhs.sagepub.com at UNIV PRINCE EDWARD ISLAND on September 22, 2015
research-article2015
JHS0010.1177/1753193415589046Journal of Hand SurgeryShort report letter
JHS(E)
Short report letter
The Journal of Hand Surgery (European Volume) XXE(X) 1–2 jhs.sagepub.com
The ‘super digit’ revisited Dear Sir, Figure 1 shows the right hand of a 28-month-old boy, with no other physical anomalies and otherwise normal development. The radiograph (Figure 2) shows two metacarpal bones (index and middle) and two well defined proximal phalanges fused at their heads to support a single distal digit. Because of the almost 90° of angulation between the heads of both proximal phalanges, there is significant divergence between the index and middle metacarpal bones. This anomaly is difficult to classify and we regard it as a variant form of ‘super digit’, a term coined by Wood (1990). Since then, the concept has seen little development. In his series of 24 fingers, Wood classified the super digit as type I, composed of two metacarpals supporting a finger, and type II, a single metacarpal that supports two or more digits distally. Type I was sub-classified as: type IA, where two metacarpals support a single, well defined but enlarged digit; type IB, with two digits evolving into one (i.e. an incomplete fusion along the longitudinal axis); type IC, with a large delta proximal phalanx supporting a fairly normal distal digit (type IC1) or two distal digits (type IC2). Type II is divided in four groups: type IIA, a single metacarpal supporting two digits, each with three well defined phalanges; type IIB, with a large (type IIB1) or split (type IIB2) proximal phalanx, supporting two distal digits; type IIC and type IID. Although not clearly defined by Wood, we interpret type IIC as having a single proximal delta phalanx supporting two almost completely fused distal fingers (type IIC1) or two proximal delta phalanges with two fingers with soft tissue syndactyly (type IIC2). Type IID seems to be associated with polysyndactyly, with a single (type IID2) or split or multiple proximal phalanges (type IID1). With 25 years of experience, Wood prudently advised against surgery to try to make two fingers out of a super digit; 14 years later, Dao et al. (2004)
Figure 1. The appearance of the right hand.
Figure 2. Radiograph of the hand.
Downloaded from jhs.sagepub.com at UNIV PRINCE EDWARD ISLAND on September 22, 2015
2
The Journal of Hand Surgery (Eur)
maintained the same opinion. The contraindication for surgery in super digits has been repeated in several textbooks, mainly in chapters on syndactyly, citing Wood’s original article. In fact, Wood cautioned against trying to separate super digits; he did not clearly state an absolute surgical contraindication to every problem, such as angulation, that might occur. Regarding the present case, there is good mobility and dexterity in the right hand, so we see no point in operating, given the current status. However, we do feel that with normal growth of both the metacarpals and proximal phalanges, a situation might occur in which, as a result of metacarpal divergence, the distance between the thumb and the ring and little fingers may affect grip. Then, a possible solution would be to excise the radial proximal phalanx (preserving part of the head) and restore the middle finger anatomy with reconstruction of the collateral ligament, a wedge osteotomy and reconstruction of the transverse metacarpal ligament. The unique characteristics of this case do not fall into Wood’s original classification, since there are two metacarpal bones and two well defined proximal phalanges, fused only at their heads to support a distal digit, and also prominent metacarpal divergence,
not found in type I. If more similar cases are found, perhaps a new category (type III) could be established, bearing in mind that there were only one or at most two examples of each type of anomaly in Wood’s original article. Conflict of interests None declared.
References Dao KD, Shin AY, Billings A, Oberg KC, Wood VE. Surgical treatment of congenital syndactyly of the hand. J Am Acad Orthop Surg. 2004, 12: 39–48. Wood VE. Super digit. Hand Clin. 1990, 6: 673–84.
J. Nunes da Costa and J. Matias, Department of Plastic, Reconstructive and Maxillofacial Surgery, Hospital de Egas Moniz, CHLO, Lisbon, Portugal Corresponding author: [email protected]
© The Author(s) 2015 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav doi: 10.1177/1753193415589046 available online at http://jhs.sagepub.com
Downloaded from jhs.sagepub.com at UNIV PRINCE EDWARD ISLAND on September 22, 2015
