The effect of low intensity ultrasound and bioabsorbable self-reinforced poly-L-lactide screw fixation on bone in lateral malleolar fractures

Introduction There are no previous reports of low intensity pulsed ultrasound therapy in connection with bioabsorbable fracture fixation. In this randomised, prospective, double-blind and placebo-controlled study, the effects of ultrasound on bone mineral density and bone healing were examined in lateral malleolar fractures fixed with a bioabsorbable self-reinforced poly-L-lactide screw (SR-PLLA). Materials and methods Thirty adult patients with SR-PLLA screw-fixed lateral malleolar fracture underwent ultrasound therapy 20 min daily for 6 weeks. Half of the patients were provided randomly with a sham ultrasound device. Bone mineral density and bone healing were assessed by dual-energy X-ray absorptiometry (DXA) and by radiographs. Results Bone mineral density of the fractured lateral malleolus tended to increase slightly during 12 weeks of follow-up. The increase was symmetrical and statistically non-significant between the ultrasound and non-ultrasound group. All the fractures healed uneventfully. The biocompatibility of the bioabsorbable SR-PLLA fixation device and low intensity pulsed ultrasound was good. Despite the slight tendency for more frequent callus formation in the ultrasound group, no statistically significant effect of low intensity pulsed ultrasound on lateral malleolar fracture healing could be observed. Conclusion It was not possible to observe any statistically significant effect of low intensity pulsed ultrasound on lateral malleolar fracture healing in this study. Further studies are needed to examine the role of ultrasound therapy in the healing of fractures treated with bioabsorbable fixation devices.