Bone mineral density in fractures treated with absorbable or metallic implants.

Absorbable fixation devices have been clinically used in the fracture treatment for over ten years. No studies have been published where bone mineral density has been measured after bone consolidation comparing absorbable and metallic fixation. In this study the bone mineral density was measured after operative ankle fracture treatment with absorbable self-reinforced polyglycolic acid (SR-PGA) screws (14 patients) or with absorbable self-reinforced polylactic acid (SR-PLLA) screws (eight patients) compared with metallic fixation (17 patients). The overall results were radiologically good in every group. A statistically significant difference in the bone mineral density (BMD) was found only in the distal tibial metaphysis between SR-PGA screw and metallic fixation. The BMD increased in the distal tibia after SR-PGA screw fixation by an average 18.3%. The average change of BMD in the distal tibia after SR-PLLA screw fixation decreased by 6.4% while after metallic fixation the average change of MBD decreased by 18.6%. Bone mineral density measurements in the present study may indicate osteogenetic capacity of polyglycolide implants in the bone after fracture or osteotomy fixation. On the other hand, metallic implants showed negative effects to the bone.