Initial Thoughts Concerning Congenital Differences Of The Upper Extremity

Treating children with congenital hand and arm differences brings tremendous satisfaction for many reasons. These conditions force patient care providers to think deeply about the structure and function of a hand and arm. Through this academic exercise, we develop an intimate understanding of the hand and arm that help us improve treatments and find creative solutions when needed. More significantly, participating in the journey that ultimately leads a child to improved function and a more natural appearance is personally fulfilling. The ability to physically manipulate and interact with our physical environment is a critical part of what makes us human, so helping children with congenital limb differences is gratifying. This journey, furthermore, requires the expertise of and interactions with a variety of health professionals who share similar professional interests and get a great deal of per­sonal and professional satisfaction from working with these children and their families. Supporting the functional needs of these children is a team sport.

Understanding where a condition lies within the broad spectrum of known congenital limb differences is daunting, but it also is a natural place to begin the treatment process. This classification helps us determine where our journey with a particular child begins.

Adapting a system first described
by Entin et al.,¹ and then later modified by Swanson et al.,^2-4 the International Federation of Societies for Surgery of the Hand (IFSSH) adopted a ­classification for congenital hand and upper-extremity differences in 1980.⁵ Congenital differences were grouped into one of seven categories based upon resemblances that were understood, and in some cases presumed, to reflect similar etiologies. The seventh category was reserved for a group of disparate conditions that seemed to have no relationship to each other, or any of the conditions in the other six categories: chromosomal abnormalities, achondroplasia, and Marfan syndrome.

Few classifications are perfect, and this system is no exception. De Smet et al. found that 7 percent of these patients were not defined by a single category, and 8 percent of the time they found the patient’s difference impossible to classify.⁶ Other challenges included children who presented with multiple deform­ities; difficulties differentiating between symbrachydactyly, brach­ydactyly, and transverse arrest; and congenital abnormalities that could fall under several categories.⁷ The Japanese Society for Surgery of the Hand modified the original IFSSH classification in an attempt to address these challenges.⁸

The approach to the organization and classification of congenital differences of the hand and upper extremity has recently undergone an evolution to both match our growing knowledge and understanding of these conditions, and to account for the difficulties of the previous classification systems. Research over the last several years, for example, has demonstrated links between conditions that were previously thought to be unrelated and vice versa.^9–13 We understand, for example, that hypoplastic thumbs are a part of the spectrum of radial longitudinal deficiency. We have come to accept that phocomelia is also a longitudinal deficiency. We have learned to distinguish symbrachydactyly as distinct from cleft hands.­ In 2009, Paul Manske and Kerry Oberg first published a review of the IFSSH classification and an update on our understanding of the developmental biology behind congenital differences of the hand.¹⁴ The authors proposed modifications including merging some of the categories into one “super category.” With the contributions of other noted scientists, this ultimately evolved into a new system that reorganized these conditions based upon the most current understanding of the developmental biology and etiology of congenital limb differences.^12,15 The Oberg-Manske-Tonkin (OMT) classification, named after the principals behind the system, represents a significant forward step (Table 1, Oberg-Manske-Tonkin Classification for Congenital Hand Anomalies,¹⁸  is available at www.oandp.org/page/ATcurrent.).

The OMT classification has helped solve many of the challenges of the previous system. Tonkin et al. and Bae et al. demonstrated very good reliability among clinicians applying this system to populations of children with congenital hand and upper-extremity differences.^15,16 There were few, if any, children that could not be classified. Ekblom et al. sought to apply this classification to children with congenital differences that they encountered over a ten-year period.¹⁷ The authors found that the OMT system was more useful than the previous IFSSH system. All these investigations however, still found some difficulties. A consistent, established solution for classifying children with multiple anomalies, certain congenital syndromes where children might manifest different hand anomalies, and certain conditions (arthrogryposis, general hypoplasias, subtypes of brachydactyly) remains elusive. At the same time, the OMT system was developed with sufficient plasticity to accommodate new information and understandings.¹⁸ The OMT system is still an improvement over the IFSSH system, and the current shortcomings of the OMT system may be solved.

Organization and classification systems for congenital difference of the hand and upper extremities provide the clinical team with a starting point when con­fronted with the task of helping a child who presents with an anomaly. Once the clinician knows where to start, the journey can begin.

Alan Peljovich, MD, MPH, FAOA  Orthopaedic Hand Surgeon The Hand & Upper Extremity Center of GeorgiaChildren’s Healthcare of Atlanta [email protected]

References are available at  www.oandp.org/page/ATcurrent.