Views on the Oberg-Manske-Tonkin Classification System for Congenital Anomalies of the Hand and Upper Limb

IFSSH Scientific Committee on Congenital Hand Conditions

The Oberg, Manske and Tonkin (OMT) Classification of Congenital Hand and Upper Limb Anomalies was adopted as the official IFSSH classification in 2014 with recommendations for 3-yearly reviews and updates. This report examined the evidence and feedback from the scientific community to see whether changes to the 2020 OMT should be made. The Committee concluded that no current changes are required, but highlighted a number of areas where further research and discussions are needed. These areas include the conditions of symbrachydactyly vs transverse arrest, the ongoing challenge with classifying syndactyly, and the nomenclature of arthrogrypotic conditions. The OMT Classification continues to enjoy high inter- and intra-rater reliability, thus establishing its central place as a robust classification system in various registries around the world.

Epidemiology of Congenital Upper-Limb Anomalies in Southern Taiwan Based on the Updated Oberg, Manske, and Tonkin Classification: A Series of 1,335 Anomalies in 1,188 Patients

PURPOSE

This study aimed to investigate the relative frequency of congenital upper-limb anomalies (CULAs) in southern Taiwan using the 2020-updated the Oberg, Manske, and Tonkin (OMT) classification system and evaluate the practicality of the new classification system.

METHODS

We retrospectively reviewed patients with CULAs from 1987 to 2021 at a referral center in southern Taiwan. All patients were analyzed based on medical records, photographs, and radiographs, and the anomalies were classified according to the 2020 OMT classification system.

RESULTS

A total of 1,188 patients with 1,335 CULAs were retrospectively reviewed. The results demonstrated that the most common type of CULA was malformations (1,092 cases), followed by dysplasias (144 cases), syndromes (51 cases), and deformations (48 cases). Among the malformations, radial polydactyly was the most common anomaly (732 cases), followed by simple syndactyly (66 cases). Among the dysplasias, camptodactyly was the most common anomaly (52 cases), followed by thumb-in-palm deformity (45 cases) and vascular tumors (17 cases). In the deformations, constriction ring sequence accounted for all cases. Poland syndrome (21 cases) occurred most often in the category of syndromes.

CONCLUSIONS

The results of this study show that radial polydactyly (732 cases, 55%) is the most common CULA in southern Taiwan, followed by simple syndactyly (66 cases, 5%) and then camptodactyly (52 cases, 4%).

CLINICAL RELEVANCE

The OMT classification system is reasonably practical for precise classification of CULAs and enables easy comparison of studies over different time periods. However, continually updating the OMT classification system is required to better categorize the highly variable presentations of CULAs.

Congenital Upper-Limb Differences: A 6-Year Literature Review

➤ The Oberg-Manske-Tonkin (OMT) classification of congenital hand and upper-limb anomalies continues to be refined as our understanding of the genetic and embryonic etiology of limb anomalies improves.➤ We have conducted an evaluation of graft and graftless techniques for syndactyly reconstruction; strengths and drawbacks exist for each technique.➤ Treatment for radial longitudinal deficiency remains controversial; however, radialization has shown promise in early follow-up for severe deformities.➤ Recent emphasis on psychosocial aspects of care has demonstrated that children with congenital upper-limb differences demonstrate good peer relationships and marked adaptability.

Hypothesis: Symbrachydactyly

The term symbrachydactyly has been used for the phenotype of two or three short fingers or toes, hypoplasia of the middle and distal phalanges and variable syndactyly of the affected digits. Some clinicians have extended this diagnosis to include other phenotypes, specifically cleft hand, terminal transverse limb defects, hypoplasia of the thumb and fifth finger with nubbins for fingers 2, 3, and 4 and the hand deformity of the Poland anomaly. A malformations surveillance program can identify enough affected infants to characterize a phenotype. In the Active Malformations Surveillance Program in Boston (1972-2012) among 289,365 births, all infants and fetuses with structural abnormalities were identified from reading the examination findings by the pediatricians and pathologists and the results of diagnostic tests. Liveborn and stillborn infants were included, as well as fetuses from elective terminations because of anomalies identified in prenatal testing. We present the findings in 14 infants, all liveborn, who had symbrachydactyly of one or both hands (n = 12) or feet (n = 2). We suggest restricting the term symbrachydactyly to this single phenotype to improve counseling and to focus future research on identifying the cause(s).

The importance of embryology for parents of children with congenital hand differences

This study aimed to determine whether embryology knowledge or explaining the possible developmental pathway error was important for parents of affected children, and to secondarily determine if there was a relationship between desired knowledge of embryology and disease severity, maternal age group or maternal level of education. Using a self-administered questionnaire, a significant proportion of responding parents considered knowledge of embryology important (32 out of 43). We found a significant association between the importance of embryology knowledge for parents and the disease severity. However, the importance and level of knowledge desired was not related to maternal age or level of education. This study demonstrated the importance of explaining the associated developmental errors in the congenital hand consultation, particularly in severe anomalies. Surgeons should familiarize themselves with embryology to provide an explanation as to why congenital hand differences happen, which may provide better psychological support for parents of these children.

The Oberg-Manske-Tonkin (OMT) Classification of Congenital Upper Extremities: Update for 2020

A new classification for congenital upper-extremity anomalies was first published in 2010. It has come to be known as the OMT classification highlighting the thought leaders behind it: Kerby Oberg, Paul Manske, and Michael Tonkin. Based on a dysmorphology framework, the OMT has been adopted by the International Federation of Society for Surgery of the Hand and surgeons who treat congenital upper-extremity anomalies. As predicted in the first publication, updates will be necessary based on an improved understanding of morphogenesis; the first update was in 2014 and this represents the second update to the original OMT classification. We carefully reviewed all aspects of the OMT classification, its current stratification, and updated literature on the developmental basis of limb anomalies. We also considered the clinical usefulness and challenges of the classification through discussions with stakeholders and those who care for patients with congenital upper-limb anomalies. These factors guided the current modifications of the OMT classification. In providing the updated classification, we provide the rationale for these changes. The updated OMT classification is by no means final. As our understanding of congenital anomalies progresses, we anticipate subsequent updates in the years to come.

Documenting Combined Congenital Upper Limb Anomalies Using the Oberg, Manske, and Tonkin Classification: Implications for Epidemiological Research and Outcome Comparisons

PURPOSE

Congenital upper limb anomalies (CULAs) exhibit a wide spectrum of phenotypic manifestations. To help the clinician evaluating this variety of CULAs, the Oberg, Manske, and Tonkin (OMT) classification was recently introduced. The OMT classification allows for documentation of combined hand anomalies. However, subsequent epidemiological and validation studies using the OMT scheme commonly registered only the main anomaly per arm. This study illustrates both the deficits of single diagnosis documentation as well as the merits of registering every anomaly for epidemiological research, outcome comparison, and overall applicability of the classification.

METHODS

We retrospectively reviewed patients visiting the Erasmus MC - Sophia Children's Hospital between 2012 and 2014. All congenital anomalies of both limbs were classified according to the OMT scheme. The frequency of combined diagnoses as well as recurrent combinations were analyzed. The relation to the coregistered syndromes was studied.

RESULTS

We included 746 patients, 79.5% of whom could be documented with a single OMT diagnosis. In 20.5%, a combination of OMT diagnoses was documented. We documented 149 different combinations: 102 were documented once, 47 were documented repeatedly (n = 196); for example, in patients with Greig syndrome. The prevalence of this syndrome was significantly higher in patients with a combination of radial polydactyly, ulnar polydactyly, and/or syndactyly (2.9% vs 33.3% and 60% in patients with 1 vs 2 and 3 diagnoses).

CONCLUSIONS

Documentation of combined OMT diagnoses is required in a fifth of the patients. Not doing so will cause loss of phenotypic information and can hamper outcome comparison and epidemiological research. Documentation of combined OMT diagnoses can help to identify subgroups within a population, for example, patients with an underlying syndrome. Last, combined documentation of diagnoses improves flexibility of the classification and thereby better allows universal application.

CLINICAL RELEVANCE

Consensus on the application of the OMT classification is critical to achieving the universal adoption of the system by hand surgeons and other medical professionals.