Tendon safety profiles of fragment-specific fixations of the distal radius extending beyond the watershed line

Introduction: The treatment of complex intra-articular fractures of the distal radius may require the use of ‘fragment specific’ plates potentially irritating the flexor tendons. Our hypothesis is that there may be different rates of tendon irritation depending on the level of projection (radial and/or ulnar) of the plate at the watershed line. We report our experience with a cohort of 113 patients comparing four different plates. Methods: We conducted a single-centre study with prospective inclusion of patients with distal radial fractures from May 2022 to March 2025. The primary objective was to evaluate the rate of tendon irritation according to the type of specific fixation used for intra-articular fractures. At the 6 month visit, an ultrasound was performed to assess the presence or absence of tendon irritation, along with a computed tomography scan to evaluate proper application of the plate to the bone. Results: Forty-two ulnar hook plates (Medartis and Newclip Technics), 31 extradistal plates (Newclip Technics), 21 adjustable anterior rim plates (Medartis) and 19 curved ‘babyfoot’ plates (Medartis) placed distal to the watershed line were used for the fixations. At 6 months, ultrasound revealed tendon irritation in nine cases involving hook plates, 15 involving extradistal plates, 10 involving babyfoot plates and none involving adjustable anterior rim plates. There was a significant difference in the frequency of tendon irritation between plate types ( p < 0.001). Conclusion: Our results suggest that specific, ulnar side fixation, ideally with an adjustable plate, may significantly reduce the risk of tendon irritation after complex distal radial articular fractures. Level of evidence: III