Biomechanical comparison of bioresorbable F‑u‑HA/PLLA screw and tension band wire fixation in medial malleolar fractures

The authors have recently reported that forged composites of raw particulate unsintered hydroxyapatite/poly-L-lactide (F-u-HA/PLLA) screws are useful for the treatment of medial malleolar fracture. However, the biome-chanical properties of these screws have not yet been fully elucidated. The aim of the present study was to compare the biomechanical properties of F-u-HA/PLLA screws with those of tension band wiring (TBW) using medial malleolar fracture models obliquely oriented at 45[drgrees] angles in synthetic tibial bones. Fractures were fixed using two 4.5-mm-diameter partial thread F-u-HA/PLLA screws, two 4.5-mm-diameter full thread F-u-HA/PLLA screws, or TBW. The fracture models were tested parallel to the distal joint surface and parallel to the fracture line. The compression load at 1, 2, 3, 4 and 5 mm of fracture displacement was assessed. The compression load parallel to the distal joint surface at 3, 4 and 5 mm of fracture displacement was significantly higher in the partial thread screw group than in the TBW group (P