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.