Review Article Clinics in Orthopedic Surgery 2011;3:172-177 • http://dx.doi.org/10.4055/cios.2011.3.3.172 Congenital Differences of the Upper Extremity: Classifi cation and Treatment Principles Moon Sang Chung, MD Department of Orthopedic Surgery, Seoul National University College of Medicine, Seoul, Korea For hand surgeons, the treatment of children with congenital differences of the upper extremity is challenging because of the diverse spectrum of conditions encountered, but the task is also rewarding because it provides surgeons with the opportunity to impact a child’s growth and development. An ideal classifi cation of congenital differences of the upper extremity would refl ect the full spectrum of morphologic abnormalities and encompass etiology, a guide to treatment, and provide prognoses. In this report, I review current classifi cation systems and discuss their contradictions and limitations. In addition, I present a modifi ed classifi ca- tion system and provide treatment principles. As our understanding of the etiology of congenital differences of the upper extrem- ity increases and as experience of treating diffi cult cases accumulates, even an ideal classifi cation system and optimal treatment strategies will undoubtedly continue to evolve. Keywords: Upper extremity, Congenital differences, Classifi cation, Treatment principles One to two percent of newborns are born with congenital In this article, I review the current classifi cation sys- defects, and 10% of them have congenital differences of tems for congenital diff erences of the upper extremity, dis- the upper extremity.1,2) As congenital diff erences of the up- cuss the limitations of obtaining the goals mentioned, and per extremity are a significant challenge, the reconstruc- suggest a classifi cation system that was modifi ed aft er the tive surgeon has a unique opportunity to positively aff ect Swanson/International Federation of Societies for Surgery the child’s growth and development.3) of the Hand (IFSSH) classifi cation.6,7) I also present prin- Th e primary purpose of a classifi cation system is to ciples of treatment of congenital difference of the upper increase communication about the specific features of a extremity according to the suggested system. condition between physicians, and provide the basis for discussion and comparison of information regarding epi- CURRENT CLASSIFICATION SYSTEMS demiology and treatment results. Th erefore, an ideal clas- sifi cation should refl ect the full spectrum of morphologic Various classification systems are divided according to abnormalities and should be simple and logical for physi- their basis of foundation; descriptive, anatomic or topo- cians to remember and to use, and would also incorporate graphical, embryologic, teratologic sequencing, genetic, etiology, guide treatment, and provide prognosis,4,5) which and diff erent combinations of these. is still unavailable in congenital differences of the upper Descriptive classifi cation is based on fi ndings of de- extremity. formity, such as radial clubhand, which describes a radially deviated hand looking like a golf club, or camptodactyly, meaning a fl exed fi nger. Although this system is intuitive and commonly used as a diagnosis in clinical practices, it Received July 26, 2010; Accepted October 5, 2010 depends on the confusing Greek and Latin terminology Correspondence to: Moon Sang Chung, MD and has little scientifi c value. S Seoul Orthopedic Specialty Hospital, Metan-dong, Suwon 443-370, Korea A more developed system is the anatomic or topo- Tel: +82-31-225-7000, Fax: +82-31-213-2600 E-mail: [email protected] Copyright © 2011 by Th e Korean Orthopaedic Association Th is is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Clinics in Orthopedic Surgery • pISSN 2005-291X eISSN 2005-4408 173 Chung. Congenital Diff erences of the Upper Extremity Clinics in Orthopedic Surgery • Vol. 3, No. 3, 2011 • www.ecios.org graphical classifi cation based on anatomic fi ndings or the the separation of morphologically similar congenital dif- extent of involvement. Syndactyly is a kind of descriptive ferences and creating a major contradiction to accept intu- classifi cation for a fi nger deformity, but complete, incom- itively.5,14) Tonkin 14) points out that the diff erence between plete, simple or complex syndactyly is an anatomic clas- abnormal formation and abnormal induction appears to sification and indicates the extent of involvement. This be one of semantics. can guide treatment recommendations and sometimes Congenital differences can be classified according prognosis. Similarly, most sub-classifications for various to their severity of expression, which is called teratologic diagnostic conditions are based on anatomy, such as the sequence classifi cation. Although this classifi cation is not Wassel classifi cation for thumb polydactyly which is based comprehensive of all anomalies, this system is oft en used on the level of thumb bifurcation.8) Frantz and O’Rahilly9,10) for classification for specific conditions, as the extent of further developed the anatomic or topographic classifi ca- pathology can determine function and guide treatment. tion and expanded the concept of intercalary defi ciencies. For example, teratologic sequencing of thumb hypoplasia Th ey divided limb defi ciencies into terminal and interca- as used in Blauth and Manske’s 5 category system classifi es lary, and each into transverse and paraxial. thumb hypoplasia according to the severity of hypoplasia The anatomic classification system was further de- and is helpful for directing the treatment (Table 2).15,16) veloped into embryologic classifi cation by Swanson et al.11) Finally, there can be a classification system based in 1964, which was based on the concept that anomalies on particular genetic or molecular abnormalities. For should be grouped according to the part that were aff ected instance, defects in the HOXD13 have been implicated during development. In the Swanson classification, each in several common congenital hand differences such as limb malformation is classifi ed according to the most pre- syndactyly and polydactyly.17) However, this type of classi- dominant anomaly and is placed into one of seven catego- fi cation may be cumbersome as the genetics are extremely ries (Table 1). Th is system was accepted by the American complex and involve multiple steps and interactions be- Society for Surgery of the Hand (ASSH), the IFSSH, and tween many genes and proteins, in addition to the interac- the International Society for Prosthetics and Orthotics tion with environmental factors.5) Progress in understand- (ISPO), and is now termed as the IFSSH classifi cation.6) ing of these complex genetic and molecular interactions Recently, the Japanese Society for Surgery of the may contribute to a better classifi cation scheme and guide Hand (JSSH) suggested a modifi cation of the IFSSH sys- potential genetic treatment options. tem, adding two groups; “Abnormal induction of rays” and 12) “Unclassifi able cases.” Th e category of “Abnormal induc- LIMITATIONS OF THE IFSSH CLASSIFICATION tion of rays” includes syndactyly, the central polydactyly- cleft hand-osseous syndactyly complex, and triphalangeal At present, the most widely accepted classification is the thumb. This concept was based on recent embryologic IFSSH classification. However, it has been criticized for studies supporting a common etiology for central poly- its inherent limitations because it attempts to incorporate actyly, syndactyly, and typical cleft hand.13) Although this etiology into morphologically-based classifi ciation,4,14) and makes sense from an embryologic standpoint, the new cat- is difficult to classify complex cases, especially with the egory separates central polydactyly from radial and ulnar polydactyly that are classifi ed as “Duplication,” resulting in Table 2. Classifi cation of the Hypoplastic Thumb15,16) Table 1. The Classification System Developed by the International Type 1 Minimally shortened and narrowed structures Federation of Societies for Surgery of the Hand6,7) Type 2 Mild underdevelopment of all structures; short bones; small diameters; mild thenar muscles hypoplasia; unstable thumb MCP I. Failure of formation joint; narrow fi rst web space II. Failure of differentiation Type 3A Stable CMC joint; signifi cant decrease in the thumb size; severe intrinsic and extrinsic muscle hypoplasia; unstable MCP joint; III. Duplication narrow fi rst web space IV. Overgrowth Type 3B Type 3A with an unstable CMC joint V. Undergrowth Type 4 Pouce fl ottant; rudimentary thumb VI. Congenital constriction band syndrome Type 5 Complete aplasia of the thumb VII. Generalized skeletal abnormalities MCP: metacarpophalangeal, CMC: carpometacarpal. 174 Chung. Congenital Diff erences of the Upper Extremity Clinics in Orthopedic Surgery • Vol. 3, No. 3, 2011 • www.ecios.org Table 3. The Author’s Classifi cation of Congenital Differences of the Upper Extremity Control failure Formation failure Under-formation Longitudinal: radial/central/ulnar defi ciency, madelung deformity Transverse: congenital amputation, constriction band syndrome Mixed: symbrachydactyly Over-formation Longitudinal: hyperphalangism Transverse: polydactyly, mirror hand Mixed: polydactyly with hyperphalangism, polydactyly