Hand SurgeryTwo-Stage “On-Top Plasty” for Thumb Polydactyly With a Floating Ulnar Thumb 3 Case ReportsZhong, Wenyao MD; Tian, Wen MMed; Sun, Liying MD; Yin, Yuehan MB; Zhang, Nan MBAuthor Information From the Department of Hand Surgery, Being Jishuitan Hospital, Beijing, China. Received March 9, 2020, and accepted for publication, after revision June 30, 2020. Conflicts of interest and sources of funding: This study was supported by BeiJing JiShuiTan Hospital Foundation for Young Scholars (code: QN-201914) and The National Key Research and Development Program of China (2016YFC0901500). The authors declare no conflict of interest. This work did not receive any funding from any of the following organizations: National Institutes of Health (NIH); Wellcome Trust; Howard Hughes Medical Institute (HHMI); RCUK. Compliance with Ethical Standards: Research involving Human Participants and/or Animals. This article does not contain any studies with human participants or animals performed by any of the authors. Reprints: Wen Tian. MMed, Department of Hand Surgery, Being Jishuitan Hospital, Xicheng District Xinjiekou, No. 31 East St, Beijing 100035, China. E-mail: email@example.com. Annals of Plastic Surgery: November 2020 - Volume 85 - Issue 5 - p 502-504 doi: 10.1097/SAP.0000000000002536 Buy Metrics Abstract We present 3 cases of thumb polydactyly treated with a 2-stage “on-top plasty” technique. For all the 3 cases, the ulnar thumbs floated in the first web with a skin pedicle, and the radial thumbs presented hypoplasia of different degree. We designed a 2-stage “on-top plasty” technique. The first operation included transplantation of the ulnar floating thumb and construction of skin tube containing the neurovascular bundle. When followed up after the first operation, there was no vascular compromise, and all union was achieved. At the time of the second operation, the skin tube was opened up, the neurovascular bundle was transposed to the reconstructed thumb, and the first web plasty was performed. At the final follow-up, 3 cases showed acceptable results both cosmetically and functionally. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.