title: Duplicated thumb bifurcation at the metacarpophalangeal joint level: factors affecting surgical outcome.
abstract: In order that the factors causing poor surgical outcome might be clarified, 175 duplicated thumbs bifurcating at the metacarpophalangeal joint level were analyzed. Cases were further divided into types A-D, based upon the details of the bifurcation form; that is, based on the connection of the radial digit to the ulnar components by either cartilage, joint, or fibrous tissue. The incidence of each type was 16% for type A (wide cartilaginous connection between phalanges), 68% for type B (2 separate phalanges), 6% for type C (cartilaginous connection to metacarpal), and 10% for type D (fibrous connection to joint capsule). Triphalangeal types and the relative size of the excised digit were determined by the preoperative radiograph. One hundred six cases were available for evaluation with a minimum of 3 years' follow-up. Good results were obtained in 50% of types A and C and in 80% of types B and D. Three phalanges in the preserve digits were observed in 10 cases and surgery on all but 1 resulted in a fair outcome. In cases where the size of the excised digit was more than 75% of the preserved digit, the results were fair or pool in 93%. The presence of subdivisions of types A and C, of 3 phalanges in the preserved digit, and of a relatively bigger excised digit were factors causing poor results, despite intensive reconstructive surgery.
authors.affiliation: Department of Orthopedics, Nagoya University, Japan.
authors.forename: E
authors.initials: E
authors.lastname: Horii
authors.forename: R
authors.initials: R
authors.lastname: Nakamura
authors.forename: M
authors.initials: M
authors.lastname: Sakuma
authors.forename: T
authors.initials: T
authors.lastname: Miura
mesh_terms: D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006228:Hand Deformities, Congenital / Q000000981:diagnostic imaging / Q000601:surgery*; D006801:Humans; D008297:Male; D008662:Metacarpophalangeal Joint / Q000002:abnormalities / Q000000981:diagnostic imaging / Q000601:surgery*; D011859:Radiography; D013933:Thumb / Q000002:abnormalities* / Q000000981:diagnostic imaging / Q000601:surgery*; D016896:Treatment Outcome