Morphology and Mobility of the Reconstructed Basilar Joint of the Pollicized Index Finger

PurposeTo evaluate outcome and function of the reconstructed basilar thumb joint after index finger pollicization in patients presenting congenital thumb deficiency.MethodsPlain radiographs and 4-dimensional dynamic volume computed tomography scan were used to evaluate the outcome of 23 pollicizations performed on 14 children between 1996 and 2009. The mean follow-up was 8 years. Patients performed continuous movements of thumb opposition during the imaging studies. Four-dimensional scan images made it possible to visualize mobility within the reconstructed joint.ResultsIn 14 cases, union occurred in the metacarpal head/metacarpal base interface. In the 9 other cases, there was a nonunion at this interface. The reconstructed joint was mobile in 20 cases, including 3 in which there was also mobility at the site of the nonunion. In 3 cases in our series, mobility was present only at the site of the nonunion, between the base and the head of the second metacarpal. Remodeling and flattening out of the metacarpal head occurred in 16 of 23 cases. The transposed metacarpal head remained spherical in 7 cases.ConclusionsThe reconstructed joint adapts, both morphologically and functionally, allowing movement on all 3 spatial planes. Existing mechanical constraints on the reconstructed joint may explain its remodeled appearance.Type of study/level of evidenceTherapeutic IV.