Revisiting short finger and cleft type symbrachydactyly subtype differentiation utilizing the congenital upper limb differences (CoULD) registry

The purpose of this investigation was to investigate short finger and cleft type symbrachydactyly to identify the defining features of these two subtypes. This retrospective study extracted data from the Congenital Upper Limb Differences (CoULD) Registry. Five paediatric hand surgeons reviewed photographs and radiographic imaging to evaluate the characteristics of each subtype and the reliability of diagnosis and evaluated the recorded diagnosis in the registry. Final analysis included 50 short finger and 54 cleft type symbrachydactyly. Key characteristic patterns were identified for each type, with further subdivision of subtypes with notable hypoplasia of the index or ring fingers or all digits. Consensus was obtained (inter-rater reliability 78%) and reliably applied for these unique subclassifications. While no clear trend in increasing severity was identified for these two subgroups of symbrachydactyly, this re-classification exercise provides clearer definition of the different subtypes and may give insight into the developmental biology of these conditions, predict future clinical function and guide surgical outcomes.<b>Level of evidence:</b> IV.