Department of Orthopedic Surgery, University Clinic for Hand, Hip and Knee Surgery, Hospital Unit West, Holstebro, Denmark; Department of Clinical Medicine, Aarhus University, Incuba Skejby, Aarhus N, Denmark.
Department of Orthopedic Surgery, Aarhus University Hospital, Aarhus N, Denmark.
J Arthroplasty. 2020 Mar;35(3):675-682.e2. doi: 10.1016/j.arth.2019.10.027. Epub 2019 Oct 24.
Periprosthetic bone mineral density (BMD) may influence implant fixation and subsequent loosening. Unicompartmental knee arthroplasty (UKA) restores normal knee kinematics and load distribution to the surrounding bone. We studied the influence of systemic and periprosthetic BMD of the proximal tibia on migration of the tibial component of cemented medial UKA.
The cohort was dichotomized into a normal BMD group (T-score ≥ -1; n = 37) and a low BMD group (T-score < -1; n = 28) according to World Health Organization criteria. BMD of the proximal tibia and migration of the tibial component were measured with dual X-ray absorptiometry scans and stereoradiographs with 2-year follow-up.
Patients with normal systemic BMD had an 11% to15% higher BMD in all regions of interest (ROIs) compared to patients with low systemic BMD throughout follow-up. Over time, a decrease in periprosthetic BMD in ROI 1-3 was seen for both groups. The operated knees and contralateral knees showed a similar reduction in BMD in all ROIs between preoperative and 24 months. Between 12 and 24 months, the normal BMD group migrated (maximal total point motion) 0.03 mm (95% confidence interval, -0.01, 0.08) and the low BMD group migrated 0.02 mm (95% confidence interval, -0.03, 0.07). Migration over time was not influenced by change in periprosthetic BMD.
Migration of cemented medial tibial UKA was low until 24 months and was neither affected by preoperative systemic BMD nor affected by postoperative change in periprosthetic BMD. This suggests good long-term fixation despite an index difference in proximal tibial BMD.
假体周围骨密度（BMD）可能会影响植入物的固定和随后的松动。单髁膝关节置换术（UKA）恢复了膝关节正常的运动学和周围骨骼的负荷分布。我们研究了胫骨近端系统和假体周围 BMD 对骨水泥固定内侧 UKA 胫骨组件迁移的影响。
根据世界卫生组织的标准，将队列分为正常 BMD 组（T 评分≥-1；n=37）和低 BMD 组（T 评分＜-1；n=28）。使用双能 X 线吸收法（DXA）扫描和立体放射照相术在 2 年的随访中测量胫骨近端的 BMD 和胫骨组件的迁移。
在整个随访过程中，与低系统 BMD 的患者相比，具有正常系统 BMD 的患者在所有感兴趣区域（ROI）的 BMD 高 11%至 15%。两组的 ROI 1-3 中均出现假体周围 BMD 的随时间减少。在所有 ROI 中，术前和 24 个月时，患侧膝关节和对侧膝关节的 BMD 均呈相似下降。在 12 至 24 个月之间，正常 BMD 组的迁移量（最大总点运动）为 0.03mm（95%置信区间，-0.01，0.08），低 BMD 组的迁移量为 0.02mm（95%置信区间，-0.03，0.07）。随时间的迁移不受假体周围 BMD 变化的影响。
骨水泥固定内侧胫骨 UKA 的迁移率在 24 个月前较低，既不受术前系统 BMD 的影响，也不受术后假体周围 BMD 变化的影响。这表明尽管胫骨近端 BMD 存在差异，但固定效果良好。
