[Functional Outcomes of Treatment of the Mallet Finger with a Bone Fragment Using the Ishiguro Extension].

Purpose of the study: The study aims to evaluate the mid-term functional and subjective outcomes of treatment of the mallet finger with a bone fragment using the Ishiguro extension block pinning. The hypothesis was that this technique provides reliable and high-quality outcomes with a low complication rate.

Material and methods: The study included 54 patients aged 7-17 years who underwent surgery at our department between 2017 and 2022. The inclusion criteria were the diagnosis of the mallet finger with a Doyle type IVa and IVb bone fragment, subluxation of the distal interphalangeal joint, fracture fragment size greater than 30% of the articular surface on lateral view radiographs, and fragment dislocation greater than 2 mm. The surgeries were performed in line with the original description of the Ishiguro technique, with reduction and closed osteosynthesis of the fragment using Kirschner wires. The surgery was followed by fixation with a plaster cast for 4 weeks on average, and rehabilitation was recommended after pin removal. The outcomes were assessed using the QuickDASH questionnaire and the Crawford criteria.

Results: The mean QuickDASH score was 3.8, the median score was 0.0. A total of 59% of patients reported no difficulty or limitations, and 37% described minimal extension deficit with no subjective difficulty. Only 4% of patients experienced more severe difficulty such as significant extension deficit or pin track infection. No secondary subluxation of the distal interphalangeal joint was observed.

Discussion: The results of our study are in agreement with global literature, which also shows a predominantly excellent and good effect of the treatment of mallet finger by extension block pinning. Complications were associated with delayed treatment and patient noncompliance. The studies comparing different techniques show that the extension block pinning provides outcomes comparable to those achieved by other methods, or even better.

Conclusions: The Ishiguro extension block pinning is a reliable, technically and financially undemanding technique that provides excellent outcomes in treating the mallet finger with a bone fragment. The use of this technique is also supported by the fact that it can be performed as an outpatient surgery under local anaesthesia and by its low complication rate. Nonetheless, further research is necessary to specify more accurately the indication criteria for surgical management of Doyle IVa and IVb lesions.