Opposition Transfer Using the Extensor Indicis Muscle and the Extensor Pollicis Brevis Tendon

Purpose This study aimed to introduce a novel technique using the extensor pollicis brevis and extensor indicis proprius tendons as power sources for thumb opposition reconstruction in cases of severe carpal tunnel syndrome (CTS) associated with thenar muscle atrophy. Furthermore, the efficacy of this novel method and the traditional Camitz technique was compared. Methods Patients with severe CTS and thumb opposition dysfunction who underwent surgery using the novel technique (n = 7 and 9 surgeries) or the Camitz technique (n = 8 and 8 surgeries) were included in the analysis. The pre- and postoperative palmar abduction angle, thumb-ring finger opposition angle, and Kapandji score were assessed. The repeated measures analysis of variance and the Mann-Whitney U test were used for statistical analysis. Results The novel technique was associated with a significant postoperative improvement in palmar abduction angle, thumb-ring finger opposition angle, and Kapandji score. In particular, the thumb-ring finger opposition angle of patients who underwent surgery using this technique was superior to that of patients who underwent surgery using the Camitz technique. Therefore, the novel technique was highly effective in improving thumb pronation. Conclusion The novel technique using the extensor pollicis brevis and extensor indicis proprius tendons is promising for thumb opposition reconstruction in severe CTS cases. Unlike the traditional Camitz technique, this approach promotes stable thumb opposition function without requiring a pulley, thereby yielding satisfactory outcomes. Nevertheless, further studies with a larger sample size should be conducted to validate these findings. Type of study/level of evidence Therapeutic 4; Surgical technique.