The causes of the secondary deformity after the correction of the Wassel type II thumb duplication

Abstract

Objective To investigate the causes of the secondary deformity after the correction of the Wassel type Ⅱ thumb duplication. Methods The patients were divided into two groups: Group A was consisted of 37 thumbs of the 35 patients(20 females,15 males;mean age 3.6 years;range 10 months to 6 years) underwent surgery.Treatment included resection of the most hypoplastic thumb,followed by reinsertion of the articular capsule and the collateral ligament,and the articular surface of the head of the proximal phalanx was shaved,the extensor tendons were centralized on the distal phalanx or cut,and the alignment maintained with Kirschner-wire fixation for five weeks.Immobilization with orthosis was conducted for three months after withdrawing Kirschner-wire.Eight patients who had been treated at other hospitals originally for type-Ⅱ deformity and had residual deformity were included in group B,their age ranged from 1 to 6 years.Seven of them underwent scar release by a z-plasty,reefing of ulnar joint capsule,shaving articular cartilage to establish more congruent joint surfaces,and the alignment being maintained with Kirschner-wire fixation for six weeks.Immobilization with orthosis was adopted for three months after withdrawing Kirschner-wire.Results Based on the Tada scoring system,the results of group A were good in 22,fair in 5,and poor in 1 after mean one and half year follow-up(range 6 months to 30 months).In group B,the mean follow-up was 1 year and 4 months(range 6 months to 28 months),the results were good in 4,fair in 2,and poor in 1.Conclusions The main causes of the secondary deformity after the correction of the Wassel type Ⅱ congenital thumb polydactyly include the extensor tendons are not centralized on the distal phalanx,the articular capsule and the collateral ligament are not construction and the articular surface of the head of the proximal phalanx is not shaved.It is important to used orthosis after withdrawal of Kirschner-wire for the treatment of secondary deformity after the correction of the Wassel type Ⅱ thumb duplication. Key words: Hand deformities; Surgery,plastic