A minimally invasive technique for residual zigzag deformities of the thumb.

Objective: This study aimed to introduce a minimally invasive technique in correcting residual zigzag deformities after early treatment of thumb duplication followed by fixation with a cemented frame.

Methods: Nineteen patients (14 males, 5 females; mean age, 12 years; age range, 8-14 years) with residual zigzag thumb deformities were treated with the minimally invasive technique from 2017 to 2019. The function and cosmesis of the thumbs were assessed using the Japanese Society for Surgery of the Hand.

Results: The mean period between the first and the second operations was 35 months (range, 12-84 months). There were Wassel types III (n=4), IV (n=13), and V (n=2) residual zigzag thumb deformities. Preoperatively, the mean alignment deformities of the interphalangeal and metacarpophalangeal joints were 23° (12-42°) and 18° (11-33°), respectively. The mean function and cosmesis of the thumbs were 12 points (range, 8-14 points). There were 1 fair and 18 poor scores. At the final follow-up (mean, 28 months; range, 24-33 months), the mean alignment deformities of the interphalangeal and metacarpophalangeal joints were 1° (0-4°) and 18° (0-4°), respectively. The mean function and cosmesis of the thumbs were 18 points (range, 16-20 points). There were 5 excellent results, 13 good results, and 1 fair result.

Conclusion: Residual zigzag thumb deformities can be successfully corrected with the minimally invasive technique, resulting in good functional and cosmetic outcomes. The technique can be used as an alternative in selected cases.

Level of evidence: Level IV, Therapeutic Study.