North Shore Hospital, Auckland, New Zealand.
Stryker Orthopaedics, Auckland, New Zealand.
Knee Surg Sports Traumatol Arthrosc. 2020 Dec;28(12):3906-3911. doi: 10.1007/s00167-020-05886-w. Epub 2020 Feb 6.
The revision rate of unicompartmental knee arthroplasty (UKA) is higher than in total knee arthroplasty (TKA), and implant positioning may play a role. In combination with a pre-operative CT, robotic UKA may provide the ability to position the implants more precisely. The aim of this study was to investigate the influence of component prominence relative to the native joint surface on early outcomes and revisions. The hypothesis was that aiming for restoration of joint space to 0.5-1.5 mm will improve outcomes.
Retrospective analysis of prospectively collected data of 94 patients undergoing robotic-assisted UKA (Mako, Stryker) was performed. The 'prominence' of the implant surface relative to the native bony surface in sagittal plane, hip-knee-ankle (HKA) correction in coronal plane was documented intraoperatively. The mean achieved gap between two components under valgus stress captured in at least 5 different flexion angles was calculated. These were then analysed for impact on early revision rate and outcomes, stratified by gender.
Median HKA correction was 3.5° (range 0°-9.5°). Median femoral prominence was 1.5 mm (range - 0.6 to 4 mm) and median tibial prominence was 4.3 mm (2-7 mm). The median achieved gap was 1.0 mm (- 1.2 to 2.8 mm). There was no difference in achieved correction between men and women (p = n.s.) but men had a higher achieved combined prominence than women (p < 0.001). PROMs did not correlate with the average gap (p = n.s.) nor with combined prominence (p = n.s.). Two patients underwent an early revision. Lower femoral prominence was a significant predictor of revision (p = 0.045; OR = 0.21; 95% CI 0.000-0.918).
Female patients need less component prominence to achieve the same average gap balance through a range of motion, without correlation with patient's height. Intraoperatively low femoral prominence could be a reason for early revision.
IV.
单髁膝关节置换术（UKA）的翻修率高于全膝关节置换术（TKA），而植入物的定位可能起作用。结合术前 CT，机器人辅助 UKA 可能能够更精确地定位植入物。本研究旨在探讨相对于原生关节表面的组件突出程度对早期结果和翻修的影响。假设是，旨在将关节间隙恢复到 0.5-1.5mm 将改善结果。
对 94 例接受机器人辅助 UKA（Mako、Stryker）的前瞻性收集数据进行回顾性分析。术中记录矢状面植入物表面相对于原生骨表面的“突出”程度、冠状面髋膝踝（HKA）矫正。计算在至少 5 个不同弯曲角度下，在外翻应力下两个组件之间获得的平均间隙。然后根据性别对这些结果进行分层分析，以评估其对早期翻修率和结果的影响。
中位 HKA 矫正为 3.5°（范围 0°-9.5°）。中位股骨突出度为 1.5mm（范围-0.6 至 4mm），中位胫骨突出度为 4.3mm（2-7mm）。获得的平均间隙为 1.0mm（-1.2 至 2.8mm）。男性和女性之间的获得矫正无差异（p= n.s.），但男性的总体突出度高于女性（p<0.001）。PROM 与平均间隙（p= n.s.）或总突出度（p= n.s.）均无相关性。有 2 例患者接受了早期翻修。较低的股骨突出是翻修的显著预测因素（p=0.045；OR=0.21；95%CI 0.000-0.918）。
女性患者需要较少的组件突出度即可通过一系列运动达到相同的平均间隙平衡，而与患者身高无关。术中股骨较低的突出度可能是早期翻修的原因。
IV。
