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Improving fixation strength of pedicle screw by microarc oxidation treatment: An experimental study of osteoporotic spine in sheep
Author(s) -
Shi Lei,
Wang Ling,
Zhang Yang,
Guo Zheng,
Wu Zixiang,
Liu Da,
Gao Mingxuan,
Chen Huan,
Fu Suochao,
Lei Wei
Publication year - 2012
Publication title -
journal of orthopaedic research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.041
H-Index - 155
eISSN - 1554-527X
pISSN - 0736-0266
DOI - 10.1002/jor.22072
Subject(s) - fixation (population genetics) , medicine , osteoporosis , ovariectomized rat , implant , bone mineral , lumbar vertebrae , lumbar spine , lumbar , dentistry , surgery , population , estrogen , environmental health
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 < 0.05). Micro‐CT analysis showed that the tissue mineral density, bone volume fraction, trabecular thickness, and trabecular number in the MAO‐treated group were all higher than those in untreated group ( p < 0.05), and trabecular spacing was smaller ( p < 0.05). Histologically, the bone–implant interface in the MAO‐treated group was better than that in untreated group ( p < 0.05). In conclusion, pedicle screws with a bioactive surface treated by MAO can improve screw fixation strength in osteoporotic spines in sheep. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1296–1303, 2012