Zhang Fan, Xu Haocheng, Wang Hongli, Geng Fang, Ma Xiaosheng, Shao Minghao, Xu Shun, Lu Feizhou, Jiang Jianyuan
Department of Orthopedics, Huashan Hospital, Fudan University, No.12 Wulumuqi Middle Road, Shanghai, China.
Department of Research & Tech, Medtronic Greater China co., LTD, Block 11, No.3000 Long Dong Avenue, Pudong, Shanghai, China.
BMC Musculoskelet Disord. 2018 Apr 4;19(1):105. doi: 10.1186/s12891-018-2027-5.
Magnesium (Mg) released from Mg-based implants degradation is believed to be effective in improving osteogenesis, however, studies focusing on Mg-based interbody cages are limited and fusion success was never reported. As excessive Mg accumulation can inhibit new bone formation, this study is designed to explain the possible reasons for the fusion failure of Mg-based cages by analyzing the relationships between the intervertebral Mg accumulation and the resulting interbody fusion.
The experimental cage was consisted of magnesium alloy (AZ31) substrate and Silicon (Si) -containing coating. C3/C4 and C5/C6 of 24 goats were implanted with cage or autologous iliac crest bone graft (Control group), which were analyzed at 3, 6, 12, and 24 weeks post-operatively. Intervertebral Mg concentrations, Mg-related Calcium (Ca)/ Phosphorus (P) ratios, radiological evaluations and histological findings were recorded for analyzing the relationships between the three of cage corrosion, Mg accumulation, and interbody fusion.
Intervertebral Mg levels were significantly increased after cage implantation, especially in the areas that were closer to the cages at 3 weeks post-operatively, and these increased concentrations could persist up to 12 weeks post-operatively, indicating a relatively rapid corrosion process. Significantly lower Mg levels were only found at 24 weeks post-operatively, but these levels were still higher than those of the control group. In addition, Mg was found to be widely distributed at the intervertebral space since high Mg concentrations could even be detected at the posterior boundary of the vertebral body. Under this Mg accumulation profile, interbody fusion was not achieved, as indicated by the decreased Ca/P ratios, low CT fusion scores and negative histological results.
Intervertebral excessive Mg accumulation might be the primary reason for interbody fusion failure. Quantitative Mg analysis can offer insight into the association between cage degeneration and biological response.
基于镁的植入物降解所释放的镁（Mg）被认为对促进骨生成有效，然而，针对基于镁的椎间融合器的研究有限，且从未有融合成功的报道。由于过量的镁积累会抑制新骨形成，本研究旨在通过分析椎间镁积累与椎间融合之间的关系，解释基于镁的融合器融合失败的可能原因。
实验融合器由镁合金（AZ31）基体和含硅（Si）涂层组成。将24只山羊的C3/C4和C5/C6节段植入融合器或自体髂骨植骨（对照组），并在术后3、6、12和24周进行分析。记录椎间镁浓度、与镁相关的钙（Ca）/磷（P）比值、影像学评估和组织学结果，以分析融合器腐蚀、镁积累和椎间融合三者之间的关系。
植入融合器后椎间镁水平显著升高，尤其是在术后3周时靠近融合器的区域，这些升高的浓度可持续至术后12周，表明腐蚀过程相对较快。仅在术后24周时发现镁水平显著降低，但仍高于对照组。此外，由于在椎体后缘甚至可检测到高镁浓度，表明镁在椎间广泛分布。在这种镁积累情况下，椎间融合未实现，这表现为钙/磷比值降低、CT融合评分低和组织学结果为阴性。
椎间镁过量积累可能是椎间融合失败的主要原因。镁的定量分析可为融合器退变与生物学反应之间的关联提供见解。
