Thumb duplication: surgical treatment and analysis of sequels.

Between 1978 and 1988, 50 thumb duplications were operated upon at either the orthopedic department of Hôpital Trousseau (Paris) or at l'Institut Français de la Main (Paris). Following Wassel's classification, we observed a large incidence of types IV, II and VII (in that order). There was a 30% incidence of associated anomalies. The average age at operation was 15 months. We were able to review 30 patients (31 thumbs) with a mean follow-up of 30.9 months. We divided our series into two groups depending on the operative protocol. Group A: 19 patients (20 thumbs), operated on between 1978 and 1982 and reviewed at 33 months on average. Group B: 11 patients (11 hands) operated on between 1983 and 1988 and reviewed with a mean follow-up of 28.5 months. All of the children were evaluated following Wassel's and Tuch's criteria. In groupe A, only five thumbs could be considered normal, or near normal upon this reexamination. All the others were affected by various sequels, which were essentially esthetic. Only two thumbs had a functional deficit, due to instability of the MP joint in one case, and stiffness of the two joints of the thumb in the other. These poor objective results were, however, not shared by the children and their parents, since 16 of them declared themselves satisfied with the appearance and the function of the thumb. 6 patients required further surgery with an average of 2.5 operations per patient. These secondary operations gave imperfect results: out of 6 such patients, we obtained 3 fair results, and three remained poor. This relatively high proportion of sequels in our patients in group A led us to change our treatment protocol in 1983. Our revised attitude was to treat all deformities at once, and especially axial deviation with a corrective osteotomy if soft tissue surgery alone did not afford perfect realignment of the thumb. Thus, among the 11 reviewed patients of group B, 6 results could be considered to be good, 4 suffered from slight sequels, and one patient required a secondary surgery (tenolysis of the extensor apparatus) to correct an inadequate active extension of the IP joint. This result was functionally good on review. The optimal age for operation is between 12 and 18 months. Il seems to us that bad results are apparent early, after 6 to 12 months, because they are mainly due to inadequate treatment. Conversely, good short-term results seem to persist with growth, but there is an overall paucity of studies in this field.