Emerson Roger H, Higgins Linda L
Texas Center for Joint Replacement, 5940 West Parker, Suite 100, Plano, TX 75093, USA.
J Bone Joint Surg Am. 2008 Jan;90(1):118-22. doi: 10.2106/JBJS.F.00739.
The mobile-bearing feature of the Oxford unicompartmental knee replacement has the potential to optimize polyethylene wear, thereby leading to longer-term function of the implant. The function of the bearing requires intact soft tissues, with the ligaments being balanced throughout the range of motion intraoperatively through bone resection only. Final limb alignment is determined by the restored soft-tissue tension. The purposes of this study were to determine the limb alignment achieved in the absence of ligament release and to investigate the interplay of failure mode, survivorship, and limb alignment.
Fifty-five knees in fifty-one patients with medial compartment osteoarthritis had a unicompartmental replacement with an Oxford prosthesis. Evaluation included Knee Society clinical scores, radiographic evaluation, survivorship analysis, and modes of failure. The average duration of clinical follow-up was 11.8 years. Only two patients (three knees) were lost to follow-up.
The mean postoperative Knee Society knee score and function score at the latest follow-up evaluation were 75 and 90 points, respectively. The overall alignment of the knee was restored to neutral, averaging 5.6 degrees of valgus alignment. Forty-seven of the fifty-five knees had the mechanical axis crossing the central 50% of the tibial plateau. Seven knees had revision surgery, and six of them required conversion to a total knee prosthesis. The main reason for revision was the progression of arthritis in the lateral compartment, which occurred in four knees at an average of 10.2 years postoperatively. These four knees had not been overcorrected into excessive valgus at the time of the original surgery, and we found no correlation, with the numbers studied, between alignment and bearing size. Survivorship analysis showed that the rate of survival at ten years was 85% with failure for any reason as the end point, 90% with progression of lateral compartment arthritis as the end point, and 96.3% with component loosening as the end point.
With this unicompartmental knee arthroplasty, the mechanical limb alignment resulting from balancing the knee ligaments, accomplished without releasing them, was consistently through the center of the knee. Progression of arthritis in the lateral compartment was the most common reason for late failure in this series and was not related to the initial postoperative alignment.
牛津单髁膝关节置换的活动平台特性有可能优化聚乙烯磨损，从而使植入物获得更长期的功能。活动平台的功能需要完整的软组织，术中仅通过截骨在整个运动范围内平衡韧带。最终的肢体对线由恢复的软组织张力决定。本研究的目的是确定在不松解韧带的情况下实现的肢体对线，并研究失败模式、生存率和肢体对线之间的相互作用。
51例患有内侧间室骨关节炎的患者的55个膝关节接受了牛津假体的单髁置换。评估包括膝关节协会临床评分、影像学评估、生存率分析和失败模式。临床随访的平均时长为11.8年。仅2例患者（3个膝关节）失访。
在最近一次随访评估中，术后膝关节协会膝关节评分和功能评分的平均值分别为75分和90分。膝关节的整体对线恢复至中立位，平均外翻对线为5.6度。55个膝关节中有47个的机械轴穿过胫骨平台中央50%。7个膝关节接受了翻修手术，其中6个需要转换为全膝关节假体。翻修的主要原因是外侧间室关节炎进展，这在4个膝关节中发生，平均发生在术后10.2年。这4个膝关节在初次手术时并未过度矫正为过度外翻，并且我们发现，在所研究的数量中，对线与活动平台尺寸之间没有相关性。生存率分析显示，以任何原因导致的失败为终点，10年生存率为85%；以外侧间室关节炎进展为终点，生存率为90%；以假体松动为终点，生存率为96.3%。
采用这种单髁膝关节置换术，通过平衡膝关节韧带（未松解韧带）实现的机械肢体对线始终穿过膝关节中心。外侧间室关节炎进展是本系列中晚期失败的最常见原因，且与术后初始对线无关。
