Efficient repair of the flexor digitorum profundus tendon at the insertion site using the loop suture technique: a case series

Purpose: This study presents the outcomes of a modified loop-locking suture technique for repairing complete flexor digitorum profundus (FDP) tendon divisions at the terminal level. Traditional methods, such as pullout sutures or tendon fixation, are commonly used; however, this paper explores the reliability of the loop-locking suture technique.Methods: From June 2011 to January 2024, the modified loop-locking suture technique was performed in 21 cases of FDP tendon division in which the distal stump was less than 1 cm in length. Core and epitendinous sutures were made using polydioxanone 4-0 and poliglecaprone 25 4-0. The study focused on 13 patients aged 24 to 68 years, with an average tendon stump length of 0.61 cm. Ten cases necessitated microsurgical repair involving both arterial and nerve repair. A dorsal protective splint was used for an average of 5 weeks. The outcomes measured included active and passive range of motion, grip strength, and key and pulp pinch.Results: The mean follow-up period was 12 months. No re-ruptures occurred, although two cases required tenolysis. The average active range of motion at the distal interphalangeal joint was 61.5°. Grip strength and pulp pinch averaged 95.3% and 86.8%, respectively, compared to the contralateral side. Flexion contracture was observed in three cases, with no quadriga effect.Conclusion: The modified loop-locking suture technique provides sufficient functional recovery for FDP tendon divisions in Zone 1a and distal Zone 1b, even with a short tendon stump.