In response to Letter to the Editor regarding: prognostic value of age and Wassel classification in the reconstruction of thumb duplication. J Child Orthop (2013)7:551–557

We are pleased to see the great interest that our study on thumb duplication has generated among the community of pediatric orthopedic surgeons. We read this Letter to the Editor with great enthusiasm as it reflects some of the interesting aspects that are still under discussion in our field. We are happy to advance the discussion on thumb duplication as it may enhance our knowledge and provide better medical management of our patients. Let us address the writers’ concerns stated in their letter. Regarding the mean duration of follow-up in relation to the mean age at surgery, we have checked the mean follow-up (in months) for each age group at the time of their surgery. Excluding the youngest group, the follow-up durations were quite equally distributed among groups, although the oldest group had the shortest follow-up (and the most complications). This finding means that the larger number of complications in the older groups was not owed to longer follow-ups in these groups and thus not owed to the older final ages at the end of the follow-up. Even assuming that the youngest group had their final follow-up at a younger age than the rest of the groups, which also may be the reason there were fewer complications in this group, it would not contradict the fact that there was a progressive increase in the number of complications in Wassel groups II–IV (with the difference being statistically significant, p = 0.0002). Also, the different numbers of complications that occur in patients of older or younger ages at follow-up did not depend on differences at 5 months of follow-up but over longer periods of time in accordance with growth spurts, damage to or asymmetrical joints and bone, or tendon imbalance, as the authors of the Letter to the Editor mention. Although our mean follow-up was similar to those in other publications, we agree with the Letter’s authors that this issue should be addressed and solutions discussed. As patients lost to follow-up may significantly decrease the groups’ mean age, perhaps it would be better to include only patients up to preadolescence in these studies. Regarding the Tada scoring system, we did not make any reference to there being only one system to describe outcomes of radial polydactyly. We agree that choosing one classification system or another may influence the final results and conclusions. For this reason, and considering that Tada has been the validated functional scale used in most of the internationally published papers on thumb duplication, we believed that it made sense to use the same system to render our results comparable to those of previous studies. By using the same scale (Tada), results can be interpreted using the same criteria as were used in various other studies on thumb duplication. There was also a point made by the authors of the Letter regarding outcomes. They noted that the patient’s perception of the hand’s appearance is not addressed by the Tada system. We did note in the article (in regard to the importance of performing the surgery early) that the patient needs ‘‘to develop a normal body image ... to facilitate the social integration of the patient when they start school’’. M. Cabrera González L. M. Pérez López (&) D. Gutiérrez de la Iglesia Hand and Malformation Surgery Division, Department of Pediatric Orthopaedic Surgery, Sant Joan de Déu Children’s Hospital, University of Barcelona, Passeig Sant Joan de Déu, 2 Esplugues de Llobregat, ES08950, Barcelona, Spain e-mail: [email protected]