The Oberg, Manske, and Tonkin Classification of Congenital Upper Limb Anomalies: A Consensus Decision-Making Study for Difficult or Unclassifiable Cases.

PURPOSE: An ideal classification system promotes communication and guides treatment for congenital upper limb differences (CULDs). The Oberg, Manske, and Tonkin (OMT) classification utilizes phenotypic presentation and knowledge of developmental biology for the classification of CULDs. In this consensus decision-making study, we hypothesized that CULDs that are difficult to classify would be identically classified by a group of experienced pediatric hand surgeons. METHODS: An international consortium of 14 pediatric hand surgeons in 3 countries contributed a group of 72 difficult-to-classify CULD cases. These were identified from the clinical practices of the surgeons and from associated registries. Through a Delphi-type process, repeated efforts were made to obtain consensus for the correct OMT classification of each case utilizing clinical images and radiographs. RESULTS: The first round of discussion yielded a universal consensus for 57 cases. The remaining 15 cases continued to be put through additional rounds of the Delphi-type process. The repeat classification and discussion resulted in a final yield of 93% complete consensus in classification by the OMT. The primary challenge in diagnosis was differentiating cleft hand from ulnar longitudinal deficiency, identified as group A. Five cases were in this group, yet 2 remained without a clear consensus. Another controversial group, group B, was termed "brachy-polydactyly" and consisted of 3 cases where diagnoses varied between sympolydactyly, symbrachydactyly, or complex syndactyly. CONCLUSIONS: The Delphi-type process was feasible and effective and allowed a 93% consensus in the diagnosis of difficult-to-classify cases by the OMT Classification. There remain limitations and controversies with the OMT system, especially when classifying hands with less than 5 skeletal digits, syndactyly, and those with diagnostic overlap between ulnar longitudinal deficiency and cleft hand and those considered "brachypolydactyly." An improved understanding of the underlying etiology may be needed to determine the final diagnosis in difficult-to-classify conditions. CLINICAL RELEVANCE STATEMENT: A consensus-seeking approach is effective and feasible in addressing difficult-to-classify CULDs.