人工膝关节置换术后关节线改变的临床研究

目的观察选择保留后交叉韧带的膝关节表面置换术与不保留周围韧带的旋转膝关节置换术后关节线的改变,分析其发生原因及预防方法。方法分别选择保留后交叉韧带的膝关节表面置换术患者25例,不保留周围韧带的旋转膝关节置换患者25例,手术前、后均拍摄膝关节非负重侧位片。术前的侧位片上,平行于胫骨平台负重关节面作一条直线,测量它到胫骨结节的垂直距离（JL）;在术后的侧位片上,平行于胫骨假体负重关节面作一条直线,测量它到胫骨结节的垂直距离（JL’）。JL’和JL之间的差值（JL’-JL）为手术前后关节线的变化值,对其进行统计学处理并分析原因。结果保留后交叉韧带的膝关节表面置换后,JL’-JL为2．0mm（-1．3—7．2mm）,其中5例大于2mm;旋转膝关节置换后,JL’-JL为3．1mm（-1．5—12．3mm）,其中11例大于2mm,两者差异有统计学意义（P〈0．01）。表面置换时关节线升高的原因包括胫骨近端截骨过少、韧带的过度松解、增加股骨远端截骨、股骨假体前后径偏小等;旋转膝关节置换时,关节线的改变主要由骨缺损和缺乏韧带的限制作用所致。结论保留后交叉韧带膝关节表面置换时,虽然有某些原因可以造成关节线的改变,但是由于畸形和骨缺损相对较轻,同时周围韧带的相对完整使其关节线发生改变的几率小、程度轻。由于骨缺损相对较重,同时手术中不保留周围韧带,旋转膝关节置换时更易发生关节线位置异常,应该通过股骨内上髁等骨性标志帮助恢复正常的关节线水平。

Change in the joint line after total knee arthroplasty

Objective To investigate the change in joint line after knee arthroplasty.Methods A total of 43 patients had 25 primary cruciate-retaining total knee replacements(Link Gemini MKII)and 25 rotational knee replacements(Link Endo-Model Rotational Knee System)sacrificing collateral ligaments and cruciate ligaments.Lateral radiographs were made both preoperatively and postoperatively.The change in the relative position of the joint line preoperatively and postoperatively was defined as the difference between the perpendicular distance from the weight-bearing surface of the tibial plateau to the tibial tubercle of the natural tibia(JL)and perpendicular distance from the weight-bearing surface of the prosthetic tibial component to the tibial tubercle(JL').This distance was JL'-JL.The statistical differences between 2 groups were analyzed.Results The distance of JL'-JL was 2.0 mm(-1.3-7.2mm)in 22 patients with Gemini replacement,whereas the distance was 3.1 mm(-1.5-12.3 mm)in the other patients with rotational knee system.The difference was significant.Conclusions If the collateral ligaments and cruciate ligaments are removed during the knee replacement operations,the prosthetic joint line is likely to be malpositioned proximally.The fibular styloid and medial or lateral epicondylar reference points can be used to determine proper position of the joint line during operation.