Abstract
Mallet finger is inability to fully extend a finger due to the disruption of the extensor mechanism integrity at the distal interphalangeal (DIP) joint level. Cases with DIP joint subluxation, and avulsion fractures involving more than 30% of the DIP joint surface are candidates for surgery. Subacute/late cases have poor outcomes. Investigating the success of extension block pinning in subacute/late bony mallet finger cases is aimed. Patient demographics, the rate of DIP joint involvement in plain X-rays, subluxation status of DIP joint, the time between injury and operation, the duration of the operation, complications in post-operative follow-up, extensor lag and healing status of bone were reviewed. Patient outcomes and relation with operative delay and joint subluxation were analyzed. Mean rate of DIP joint involvement of study group was 43.4 ± 6.12%. Half of the study group (n=7) had DIP joint subluxation. Mean time from injury to operation was 29.78±20.4 days. Six patients’ time from injury to operation was longer than 5 weeks. Study group had statistically significant improvement after surgery. Preoperative mean extensor lag was 15.71° ± 7.30° and postoperative mean extensor lag was 5.57° ± 8.89°(p<0.001). At long term follow-up, technique has proven to be successful (excellent+good) in 78.5% of patients. Operating in late period (>5 weeks) and presence of subluxation did not alter the outcome (p=0.353 and p=0.149, respectively). Extension block pinning technique is a fast, easy-to-apply technique with minimal morbidity. Although it has more limited results in chronic cases, it can be used safely in the majority of cases requiring surgery.

Key words: bony mallet finger; extension block pinning; extension lag; mallet finger; surgery