Clinical Characteristics and Surgical Outcomes of Congenital Ulnar-deviated Thumbs: Delta Triphalangeal Thumbs and Irregular Epiphyses

BACKGROUND: Delta triphalangeal thumbs (DTPT) and irregular epiphysis thumbs (IET) had different anatomic deformities. Our primary purpose was to evaluate the clinical and radiographic outcomes of surgical treatment in DTPT and IET. METHODS: In total, 43 ulnar-deviated thumbs were included and categorized into 2 types according to x-ray and exploration during surgery, DTPT and IET. Surgical excision of the delta phalanx in DTPT and intraepiphysis osteotomy in IET was conducted. RESULTS: In total, 23 ulnar-deviated thumbs were classified as DTPT and 20 as IET. Ten thumbs that could not be classified initially were followed-up until they could be categorized at the mean age of 24 months. The preoperative mean degrees of ulnar deviation at the interphalangeal joints were 40 and 33 degrees, in DTPT and IET, respectively. The mean degrees were 2 and 5 degrees in final follow-up, showing significant improvement (DTPT, P<0.05; IET, P<0.05). Complications during the study included residual ulnar deviation, overcorrection, and nonunion. The stability and range of movement at the interphalangeal joint were good overall. According to the Japanese Society for Surgery of the Hand scoring system, results were excellent in 29 cases, good in 13, and fair in 1. CONCLUSIONS: Ulnar clinodactyly of the thumb occurs because of different anatomic features such as DTPT or IET. We recommend surgical treatment be postponed until the anatomic abnormality can be ascertained. Furthermore, almost all patients with ulnar-deviated thumbs had significant improvement in clinical and radiographic outcomes after surgery.