Abstract
For internal fixation of AO classification Type B ankle lateral malleolus fracture, insertion of lag screws into the fracture plane and fixation with a 1/3 tubular plate as a protecting plate are recommend. The distal end screw hall of the 1/3 tubular plate is cut to a 1/3 circle, processed to a hook-shape, and hung on the distal end of the fibula as a method. The mean time to bone fusion was significantly shortened by 1.5 months in the group fixed with the 1/3 tubular plate with this hook compared with the group without the hook in a study. The usefulness of the hook is expected based on this finding, but there are only clinical reports, and no basic data has been reported. Locking compression plates are considered as a breakthrough implant expected to improve outcomes and indicated for many cases, but regarding basic data, only biomechanical studies were performed, and no quantitative measurement in consideration of the muscles and skeleton around the ankle joint has been reported. Aiming at comparison of the function between the hook and lag screws of a 1/3 tubular plate and locking compression plate for osteosynthesis of lateral malleolus fracture, internal fixation was applied using 1/3 tubular plates with lag screws with and without the hook and locking compression plates, and the muscles, skeleton, and implant around the ankle joint were quantitatively measured. A stiffness equivalent to that of healthy bone could be achieved by all 3 internal fixations. It was clarified that the presence of the hook does not make a difference in stiffness, suggesting that active preparation of the hook is unnecessary, and that lag screws inhibit displacement, being useful to support absolute fixation, but to support biological fixation, the recent concept, may be controversial.
