Scott G, Imam M A, Eifert A, Freeman M A R, Pinskerova V, Field R E, Skinner J, Banks S A
Trauma and Orthopaedic Department, Royal London Hospital, Whitechapel, London, E1 1BB, UK
South West London Elective Orthopaedic Centre, Epsom, UK.
Bone Joint Res. 2016 Mar;5(3):80-6. doi: 10.1302/2046-3758.53.2000621.
Throughout the 20th Century, it has been postulated that the knee moves on the basis of a four-bar link mechanism composed of the cruciate ligaments, the femur and the tibia. As a consequence, the femur has been thought to roll back with flexion, and total knee arthroplasty (TKA) prostheses have been designed on this basis. Recent work, however, has proposed that at a position of between 0° and 120° the medial femoral condyle does not move anteroposteriorly whereas the lateral femoral condyle tends, but is not obliged, to roll back - a combination of movements which equates to tibial internal/ femoral external rotation with flexion. The aim of this paper was to assess if the articular geometry of the GMK Sphere TKA could recreate the natural knee movements in situ/in vivo.
The pattern of knee movement was studied in 15 patients (six male: nine female; one male with bilateral TKAs) with 16 GMK Sphere implants, at a mean age of 66 years (53 to 76) with a mean BMI of 30 kg/m(2) (20 to 35). The motions of all 16 knees were observed using pulsed fluoroscopy during a number of weight-bearing and non-weight-bearing static and dynamic activities.
During maximally flexed kneeling and lunging activities, the mean tibial internal rotation was 8° (standard deviation (sd) 6). At a mean 112° flexion (sd 16) during lunging, the medial and lateral condyles were a mean of 2 mm (sd 3) and 8 mm (sd 4) posterior to a transverse line passing through the centre of the medial tibial concavity. With a mean flexion of 117° (sd 14) during kneeling, the medial and lateral condyles were a mean of 1 mm (sd 4) anterior and 6 mm (sd 4) posterior to the same line. During dynamic stair and pivoting activities, there was a mean anteroposterior translation of 0 mm to 2 mm of the medial femoral condyle. Backward lateral condylar translation occurred and was linearly related to tibial rotation.
The GMK Sphere TKA in our study group shows movements similar in pattern, although reduced in magnitude, to those in recent reports relating to normal knees during several activities. Specifically, little or no translation of the medial femoral condyle was observed during flexion, but there was posterior roll-back of the lateral femoral condyle, equating to tibiofemoral rotation. We conclude that the GMK Sphere is anteroposteriorly stable medially and permits rotation about the medial compartment.Cite this article: Professor G. Scott. Can a total knee arthroplasty be both rotationally unconstrained and anteroposteriorly stabilised?: A pulsed fluoroscopic investigation. Bone Joint Res 2016;5:80-86. DOI: 10.1302/2046-3758.53.2000621.
在整个20世纪，人们假定膝关节是基于由交叉韧带、股骨和胫骨组成的四杆连杆机构运动的。因此，人们认为股骨在屈曲时会向后滚动，全膝关节置换术（TKA）假体也是基于此设计的。然而，最近的研究表明，在0°至120°之间的位置，内侧股骨髁不会前后移动，而外侧股骨髁倾向于（但并非必然）向后滚动——这些运动的组合等同于胫骨内旋/股骨外旋伴屈曲。本文的目的是评估GMK Sphere TKA的关节几何形状能否在原位/体内重现自然膝关节运动。
对15例患者（6例男性，9例女性；1例男性为双侧TKA）的16个GMK Sphere植入物进行膝关节运动模式研究，患者平均年龄66岁（53至76岁），平均体重指数为30kg/m²（20至35）。在多种负重和非负重的静态及动态活动期间，使用脉冲荧光透视观察所有16个膝关节的运动。
在最大程度屈曲跪姿和弓步活动期间，平均胫骨内旋为8°（标准差（sd）6）。在弓步活动中，平均屈曲112°（sd 16）时，内侧和外侧髁相对于穿过内侧胫骨凹中心的横向线分别平均位于后方2mm（sd 3）和8mm（sd 4）处。在跪姿时，平均屈曲117°（sd 14），内侧和外侧髁相对于同一条线分别平均位于前方1mm（sd 4）和后方6mm（sd 4）处。在动态上下楼梯和 pivoting活动期间，内侧股骨髁的平均前后平移为0mm至2mm。外侧髁向后平移，且与胫骨旋转呈线性相关。
我们研究组中的GMK Sphere TKA在多种活动中显示出与近期关于正常膝关节的报道中相似的运动模式，尽管幅度有所减小。具体而言，在屈曲过程中观察到内侧股骨髁很少或没有平移，但外侧股骨髁有向后滚动，等同于胫股旋转。我们得出结论，GMK Sphere在内侧前后方向上是稳定的，并允许围绕内侧间室旋转。引用本文：G. Scott教授。全膝关节置换术能否在旋转上无约束且在前后方向上稳定？：一项脉冲荧光透视研究。《骨与关节研究》2016；5：80 - 86。DOI：10.1302/2046 - 3758.53.2000621。
