Gu Tianyun, Zheng Nan, Xia Chunjie, Zou Diyang, Wang Qi, Tsai Tsung-Yuan
School of Biomedical Engineering & Med-X Research Institute, Shanghai Jiao Tong University, Shanghai, China.
Engineering Research Center for Digital Medicine of the Ministry of Education, Shanghai, China.
J Orthop Res. 2025 Oct;43(10):1757-1766. doi: 10.1002/jor.70017. Epub 2025 Jul 16.
Unicompartmental knee arthroplasty (UKA) effectively treats unicompartmental osteoarthritis (OA), but longterm outcomes are often compromised by disease progression in other compartments. Distinct impacts of fixed-bearing (FB) and mobile-bearing (MB) UKA on patellofemoral joint (PFJ) kinematics and soft tissue mechanics remain unclear. Our study aims to analyze effects of FB and MB UKA on PFJ kinematics and patellar tendon (PT) elongation and assess UKA's impact on UKA and contralateral side. A total of 24 patients (13 FB UKA, 11 MB UKA) were recruited, all with varying knee dysfunction. PFJ six-degrees-of-freedom motion, patellar lever arm and PT elongation were assessed during functional maneuvers using dual fluoroscopic imaging and virtual ligament analysis. Differences between parameters were analyzed using paired t-tests, while correlations between parameters and functional scores were assessed using Spearman correlation, with false discovery rate correction applied. We found that FB UKA resulted in a more distal and medial patellar position and increased flexion with posterior shift correlating with worse KSS scores (p < 0.05). MB UKA showed greater patellar extension and better lateral patellar positioning and better KSS scores (p < 0.05). Patellar lever arm was longer after MB UKA during single-leg lunge, whereas FB UKA differed during early sit-to-stand. Both groups experienced PT elongation on UKA side and correlated with OKS and FJS (p < 0.05). In conclusion, FB UKA offers greater knee stability but may restrict rotation and increase patellofemoral stress, requiring focused rehabilitation on alignment and quadriceps function. MB UKA better restores natural kinematics, making it preferable for active patients.
单髁膝关节置换术（UKA）可有效治疗单髁骨关节炎（OA），但长期疗效常因其他关节间室的疾病进展而受到影响。固定平台（FB）和活动平台（MB）UKA对髌股关节（PFJ）运动学和软组织力学的不同影响尚不清楚。我们的研究旨在分析FB和MB UKA对PFJ运动学和髌腱（PT）伸长的影响，并评估UKA对患侧和对侧的影响。共招募了24例患者（13例FB UKA，11例MB UKA），均有不同程度的膝关节功能障碍。在功能动作期间，使用双荧光透视成像和虚拟韧带分析评估PFJ的六自由度运动、髌杠杆臂和PT伸长。使用配对t检验分析参数之间的差异，使用Spearman相关性评估参数与功能评分之间的相关性，并应用错误发现率校正。我们发现，FB UKA导致髌骨位置更偏下和偏内侧，屈曲增加且向后移位，与较差的膝关节协会（KSS）评分相关（p<0.05）。MB UKA显示出更大的髌骨伸展、更好的髌骨外侧定位和更好的KSS评分（p<0.05）。在单腿弓步时，MB UKA后的髌杠杆臂更长，而FB UKA在从坐到站的早期有所不同。两组在患侧均出现PT伸长，且与牛津膝关节评分（OKS）和功能膝关节评分（FJS）相关（p<0.05）。总之，FB UKA提供了更大的膝关节稳定性，但可能会限制旋转并增加髌股关节应力，需要重点进行对线和股四头肌功能的康复训练。MB UKA能更好地恢复自然运动学，更适合活跃的患者。
