Aigner Christian, Windhager Reinhard, Pechmann Michael, Rehak Peter, Engeleke Klaus
Department of Orthopaedic Surgery, University of Graz Medical School, Auenbruggerplatz 5, 8036 Graz, Austria.
J Bone Joint Surg Am. 2004 Oct;86(10):2257-62. doi: 10.2106/00004623-200410000-00018.
Range of motion is a crucial measure of outcome after total knee arthroplasty. In order for maximum flexion to occur, the femur must progressively shift posteriorly on the tibia, a movement that is known as femoral rollback. Mobile bearings with free anterior-posterior translation could improve knee flexion by allowing such motion. The purpose of the present study was to determine the influence of an anterior-posterior gliding mobile bearing on the postoperative range of knee motion in patients with an intact posterior cruciate ligament.
We performed a prospective, randomized clinical trial of fifty consecutive total knee arthroplasties that were performed with use of the LCS-Universal prosthesis. Participants were randomized to receive either a deep-dish rotating platform or a mobile bearing that allowed additional anterior-posterior translation, the latter of which requires an intact posterior cruciate ligament. The ranges of motion of the knees were assessed to detect a 15 degrees difference in the active non-weight-bearing range of motion with a power (1 - beta) of 20% and with the level of significance (alpha) set at 0.05. The translation of the mobile bearing was measured with use of a standardized ultrasound technique and was correlated with maximum knee flexion. The participants and the assessor were blinded throughout the study.
At the time of the one-year follow-up evaluation, forty-eight knees were available for an intention-to-treat analysis. The mean active non-weight-bearing range of motion at one year was 113 degrees (95% confidence interval, 108 degrees to 118 degrees ) in the twenty-six knees that had received a rotating platform and 111 degrees (95% confidence interval, 115 degrees to 125 degrees ) in the twenty-two knees that had received an anterior-posterior gliding bearing (p = 0.57). In the latter group, a continuous rollback occurred in two knees. There was no significant correlation between knee flexion and anterior-posterior translation (r(2) = 0.015).
The use of a mobile bearing that allowed free anterior-posterior translation did not regularly restore femoral rollback and did not improve range of motion after total knee arthroplasty compared with the findings seen in association with the use of a rotating platform.
活动范围是全膝关节置换术后结果的关键衡量指标。为了实现最大程度的屈曲，股骨必须在胫骨上逐渐向后移位，这种运动被称为股骨后滚。具有自由前后平移功能的活动轴承可通过允许这种运动来改善膝关节屈曲。本研究的目的是确定前后滑动活动轴承对后交叉韧带完整患者术后膝关节活动范围的影响。
我们对连续50例使用LCS通用假体进行的全膝关节置换术进行了一项前瞻性、随机临床试验。参与者被随机分为接受深盘旋转平台或允许额外前后平移的活动轴承，后者需要后交叉韧带完整。评估膝关节的活动范围，以检测主动非负重活动范围有15度的差异，检验效能（1-β）为20%，显著性水平（α）设定为0.05。使用标准化超声技术测量活动轴承的平移，并将其与最大膝关节屈曲相关联。在整个研究过程中，参与者和评估者均处于盲态。
在一年的随访评估时，48个膝关节可用于意向性分析。接受旋转平台的26个膝关节在一年时的平均主动非负重活动范围为113度（95%置信区间，108度至118度），接受前后滑动轴承的22个膝关节为111度（95%置信区间，115度至125度）（p = 0.57）。在后一组中，两个膝关节出现了持续后滚。膝关节屈曲与前后平移之间无显著相关性（r² = 0.015）。
与使用旋转平台的结果相比，使用允许自由前后平移的活动轴承并不能常规恢复股骨后滚，也不能改善全膝关节置换术后的活动范围。
