The aim of this study was to compare the closed reduction interfragmentary pinning method (IPM) with the extension block technique (EBT) for bony mallet finger. Patients who underwent mallet finger operations were screened retrospectively for the following inclusion criteria: Doyle type 4c, age between 18 and 75 years, less than 4 weeks to surgery, and more than 1 year of follow-up time. Group I underwent a closed reduction IPM, and group II underwent the EBT. Lateral radiographs taken during the preoperative and final examination were used to evaluate the size and amount of displacement from the distal interphalangeal (DIP) joint and the dorsal fragment as well as the articular surface. Operation times were compiled from patient records. During the final examination, pain and DIP joint range of motion (ROM) were assessed and complications were recorded. The Crawford criteria were used for functional results. Fifteen patients in group I (8 men, 7 women) and 17 patients in group II (10 men, 7 women) were evaluated. Age, gender, time to surgery and follow-up time showed no statistically significant differences between the two groups. The differences in fragment size, preoperative and postoperative joint displacement, amount of dorsal displacement and DIP joint ROM were not statistically significant between the two groups. However, the operation time was significantly shorter time in group I than in group II (p=0.000). The average time to fracture union was significantly longer in group I (7.3 weeks) than in group II (6 weeks) (p=0.013). The EBT has faster time to union and is a safer method with lesser risk of arthritis and fragmentation. The IPM can be an alternative with shorter operation time, less pin bed infection and nail bed damage, especially in Doyle type 4c cases with large fragments.Copyright © 2021. Published by Elsevier Masson SAS.