| Objective To explore anatomic abnormalities causing congenital ulnar deviation deformity of the thumbs at the level of their distal phalanges, so as to identify the differential diagnosis and guide for surgical treatment.Methods Reviewing the clinical manifestations, X-ray films and operative findings of 68 children with congenial ulnar deviation deformity in the distal phalanges but without displacement of the tendons in their thumbs, and analyzing their anatomic abnormality as well as differential diagnosis. Besides, long-term outcome of different surgical method was followed up.Results There were 91 ulnar deviated thumbs in this study. Abnormal hypertrophic epiphyses were found in 55 thumbs. In radiograph, the epiphysis was in good apposition and alignment with its relevant distal phalanx and they got pretty close to an average of 0.83 mm, and intraepiphyseal wedge-osteotomy was performed on them. Extra bones were found to exist between the proximal phalanges and distal phalanges in the other 36 thumbs. Preoperative radiography showed a large distance and poor apposition between the distal phalanx and the extra bone which averaged to 2.81 mm, and removal of delta bone was performed in some of the triphalangeal thumbs, the others were given an operation of wedge-shape excision of the extra phalanx and its distal joint. The average duration of the follow-up period was 23 months after surgery, and the angulation revealed improvement in all cases.Conclusions Abnormal hypertrophic epiphysis and triphalangeal thumb are two different causes for congenital ulnar deviation of the distal phalanx of the thumb. Smaller distance, as well as better apposition and alignment between the hypertrophic epiphysis and distal phalanx in X-ray is the main point of identification so we can distinguish it from a triphalangeal thumb. Appropriate surgical methods should be selected according to the differential diagnosis. |
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