Department of Trauma and Orthopedic Surgery, Protestant Hospital of Bethel Foundation, University Hospital OWL of Bielefeld University, Campus Bielefeld-Bethel, Burgsteig 13, 33617, Bielefeld, Germany.
AO Research Institute Davos, Clavadelerstrasse 8, 7270, Davos, Switzerland.
J Orthop Traumatol. 2021 Feb 27;22(1):5. doi: 10.1186/s10195-021-00568-w.
Given the increasing number of osteoporotic fractures of the distal femur, screw augmentation with bone cement is an option to enhance implant anchorage. However, in implant removal or revision surgeries, the cement cannot be removed from the distal femur without an extended surgical procedure. Therefore, the aims of this study were to investigate (1) whether cement augmentation has any influence on screw removal and removal torque, and (2) whether the implantation of a femoral component of a knee arthroplasty and its initial interface stability are affected by the remaining screws/cement.
Eight pairs of fresh-frozen human female cadaveric distal femurs (mean age, 86 years) with a simulated AO/OTA 33 A3 fracture were randomized in paired fashion to two groups and fixed with a distal femoral locking plate using cannulated perforated locking screws. Screw augmentation with bone cement was performed in one of the groups, while the other group received no screw augmentation. Following biomechanical testing until failure (results published separately), the screws were removed and the removal torque was measured. A femoral component of a knee arthroplasty was then implanted, and pull-out tests were performed after cement curing. Interference from broken screws/cement was assessed, and the maximum pull-out force was measured.
The mean screw removal torque was not significantly different between the augmented (4.9 Nm, SD 0.9) and nonaugmented (4.6 Nm, SD 1.3, p = 0.65) screw groups. However, there were significantly more broken screws in in the augmented screw group (17 versus 9; p < 0.001). There was no significant difference in the pull-out force of the femoral component between the augmented (2625 N, SD 603) and nonaugmented (2653 N, SD 542, p = 0.94) screw groups.
The screw removal torque during implant removal surgery does not significantly differ between augmented and nonaugmented screws. In the augmented screw group, significantly more screws failed. To overcome this, the use of solid screws in holes B, C, and G can be considered. Additionally, it is possible to implant a femoral component for knee arthroplasty that retains the initial anchorage and does not suffer from interference with broken screws and/or residual cement.
随着股骨远端骨质疏松性骨折数量的增加，使用骨水泥进行螺钉增强是增强植入物锚固的一种选择。然而，在进行植入物取出或翻修手术时，如果不进行延长手术，就无法从股骨远端取出水泥。因此，本研究的目的是探讨：（1）骨水泥增强是否会影响螺钉的取出和取出扭矩；（2）膝关节置换的股骨部件的植入及其初始界面稳定性是否会受到残留螺钉/水泥的影响。
将 8 对冷冻的新鲜女性成人股骨远端（平均年龄 86 岁），模拟 AO/OTA 33 A3 骨折，以配对的方式随机分为两组，并用带孔锁定钢板固定股骨远端锁定板。一组螺钉进行骨水泥增强，另一组不进行螺钉增强。在生物力学测试直至失效（结果单独发表）后，取出螺钉并测量取出扭矩。然后植入膝关节置换的股骨部件，并在水泥固化后进行拔出测试。评估断钉/水泥的干扰情况，并测量最大拔出力。
增强螺钉组（4.9 Nm，SD 0.9）和非增强螺钉组（4.6 Nm，SD 1.3，p=0.65）的螺钉取出扭矩平均值无显著差异。然而，增强螺钉组有更多的断钉（17 个比 9 个；p<0.001）。增强螺钉组（2625 N，SD 603）和非增强螺钉组（2653 N，SD 542，p=0.94）的股骨部件拔出力无显著差异。
在植入物取出手术中，增强螺钉和非增强螺钉的螺钉取出扭矩无显著差异。在增强螺钉组中，更多的螺钉失效。为了克服这个问题，可以考虑在孔 B、C 和 G 中使用实心螺钉。此外，也可以植入保留初始锚固且不受断钉和/或残留水泥干扰的膝关节置换股骨部件。
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