Improving fixation strength of pedicle screw by microarc oxidation treatment: An experimental study of osteoporotic spine in sheep

Failure of fixation caused by loosening of pedicle screws in osteoporosis is a problem in spinal surgery. We compared the in vivo fixation strength between pedicle screws treated with microarc oxidation (MAO) and untreated screws in an osteoporotic model of ovariectomized sheep. The MAO treated and untreated screws were placed in lumbar vertebral bodies. After 3 months of implantation, biomechanical tests, micro-CT analysis, and histological observations were conducted to examine the performance of the two groups. At time 0, no significant difference was found between the two groups in biomechanical tests (p?>?0.05); 3 months later, higher pull-out strength and load with less displacement were detected in the MAO-treated group (p?