Midterm Surgical Outcomes of Duplicated Thumbs According to New Classification.

Emiko Horii, Shukuki Koh, Junko Otsuka, Yoshitaka Hamada, Takanori Saito

Plastic and reconstructive surgery 2023 Jul 01

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Surgical outcomes of duplicated thumbs differ depending on the branching type. The authors developed a new classification system and report surgical outcomes with an average 10.2-year follow-up. A total of 529 patients with 562 duplicated thumbs were reviewed. Surgical anatomies were compared with radiographs, and then a new classification system was developed based on branching level and bone shape observed on the radiograph: distal type (D-type), including Wassel types I and II; proximal type (P-type), including Wassel types Ⅲ and Ⅳ, and four subdivisions (Po, Pa, Pb, and Pc) according to bone structure; and metacarpal type (MC-type), including Wassel types V and VI. All hands were assessed using the Japanese Society for Surgery of the Hand evaluation form, and factors causing poor outcomes were analyzed. There were 25% D-type, 59% P-type, and 14% MC-type hands; 2% of hands were not classified. Overall, 351 hands (63%) were directly assessed when patients reached 5 years of age. Seventeen percent of hands had fair results. Good results were achieved in 90% of D- and Po-type hands. Pa-, Pb-, Pc-, and MC-type hands had lower Japanese Society for Surgery of the Hand scores than did D- or Po-type hands. Pa- and Pb-type hands tended to develop interphalangeal joint malalignment and instability, whereas Pc- and MC-type hands developed disorders in the metacarpophalangeal joint with growth. The authors' new classification system clarifies the potential pitfalls for each type of duplicated thumb. More than 90% of D- and Po-type hands obtained good results. Care should be taken with interphalangeal joint reconstruction for Pa- and Pb-type hands. Meticulous reconstruction of the metacarpophalangeal joint is essential for Pc- and MC-type hands. This analysis provides important information for surgeons and patients. Risk, IV. Copyright © 2023 The Authors. Published by Wolters Kluwer Health, Inc. on behalf of the American Society of Plastic Surgeons.

Citation

Emiko Horii, Shukuki Koh, Junko Otsuka, Yoshitaka Hamada, Takanori Saito. Midterm Surgical Outcomes of Duplicated Thumbs According to New Classification. Plastic and reconstructive surgery. 2023 Jul 01;152(1):116e-125e