Reduced Risk of FPL-Tendon Rupture in Distal Radius Fracture Treated by a Palmar V-Shaped Plate

Objectives: Palmar locking plates enabling early active motion are successfully used in distal radius fracture treatment. But some fracture types can necessitate to place a plate distally to the watershed line with the risk of rupture of the flexor pollicis longus (FPL) tendon. In addition, the indication for implant removal following palmar plating is still discussed controversially. Patients and Method: In this prospective follow-up study, 18 patients with distal radial fracture (DRF) were stabilized by a new anatomical designed V-shaped palmar plate (Medartis, Basel, Switzerland). Radial inclination (RI), dorsal tilt (DT), and ulnar variance (UV) were assessed. An independent radiologist investigated the FPL tendon by ultrasound to course within the V-space of the plate at its distal end. In addition, the gliding and course of the FPL tendon was investigated during surgery. Results: In lateral projection, the plate appeared Soong type 0 (n = 3), Soong type 1 (n = 12), and Soong type 2 (n = 3). RI measured 20° (minimum 14°, maximum 27°), DT 3.8° (minimum 0°, maximum 12°), and UV 0 mm (minimum −3, maximum 2). In sonography, the FPL tendon run within the V-space in all cases. In all Soong types, there was no contact of the FPL tendon with the plate found in ultrasound. In Soong type 2, the ulnar column of the plate protruded and caused friction of the flexor digitorum profundus (FDP) tendon in 2 patients when a fit bone/implant contact was missing. Protrusion was seen in dorsal displacement of the distal fragment ad latus and soft tissue interposition. Intraoperatively, the radial column of the plate ended proximal at the watershed line without contact to the FPL tendon. Proximal to the watershed line, the course of the FPL tendon was minimally altered after release of the pronator quadratus (PQ) and mobilizing the FPL muscle for plate positioning. It remained unaltered distal to the watershed line where the FPL tendon enters the nonreleased carpal tunnel. Conclusion: The V-shaped FPL plate spared the FPL tendon in all Soong-type plate positions. Achieved reduction of RI greater 14°, DT more than 0°, and UV better than −3 mm proofed sufficient for the V-space design to avoid friction of the FPL. Restoration of DT and firm bone/plate contact of the distal fragment are important in distal plate position. Implant removal of plates positioned Soong types 1 and 2 seems to be no more imperative. In Soong type 3, the FDP tendons should be considered to be of some risk.