Keikichi Kawasaki

Distal radius fractures-Design of locking mechanism in plate system and recent surgical procedures.

Recently, many studies have emphasized the importance of the comprehension of detailed functional anatomy of the distal forearm and wrist joint, and their biomechanics. A significant contribution which yields good functional outcomes of surgical treatment was the development of the locking plate technology; this technology has facilitated the improvement of the surgical technique for the fixation of fractures. This article reviews the locking mechanism and design of the fixation screws and plate, and the details of the surgical technique including the double-tired subchondral support procedure as it is applied to common fractures. Arthroscopic-assisted surgical procedures can be used to reduce the intra-articular fracture fragments after realignment of the distal radius with the locking plate. This technique is also useful at the time of fixation to assess soft tissue injury. The combination of arthroscopic-assisted reduction and locking plate fixation is now indicated for AO type C2 and C3 intra-articular comminuted fractures.

Comparison of Locking and Frag-Loc Screws for Fixation of Die-Punch Fragments

Background The Frag‐Loc (FL) compression screw system was designed to stabilize dorsally displaced intra‐articular dorsoulnar (die‐punch) fragments in distal radius fractures. Purpose Comparison of the biomechanical properties of fixation of the die‐punch fragment (stiffness, ultimate strength, and displacement ratio of the fragment), using the FL and traditional locking screw (LS), and using simulated distal radial fractures in cadaveric specimens under axial compressive loading. Both screws were used with a volar locking plate (VLP). Materials and Methods Eight matched pairs of formalin‐fixed cadaveric specimens of the radius were used to simulate distal radius fractures with die‐punch fragments. The die‐punch fragment was fixed using VLP with either FL group or LS group. Biomechanical properties for the two fixation systems were evaluated under axial compression loading, applied at a constant rate of 0.5 mm/min until failure. Load data were recorded and the ultimate strength and change in the gap between the die‐punch and proximal fragments measured, with the displacement ratio calculated by dividing the value of the gap before loading by the gap after loading. Failure was defined as 10 mm or more of fragment displacement, or screw failure. Results There were no differences in ultimate strength (p = 0.47) or stiffness (p = 0.061) between the two fragment fixation systems. However, the displacement ratio was lower for the FL than for the LS system (p = 0.049). Conclusion Compared with LS, the FL system lowers the displacement of die‐punch fragments under compressive loading. Clinical Relevance The FL system is effective for the treatment of distal radius fractures with die‐punch fragments.