Rimondi E, Molinari M, Moio A, Busacca M, Trentani F, Trentani P, Tigani D, Nigrisoli M
Servizio di Diagnostica per Immagini, Istituto Ortopedico Rizzoli, Bologna.
Radiol Med. 2000 Jun;99(6):420-5.
CT assessment of the axial deviation of the femoral and tibial prosthetic components in total knee arthroplasty.
January to July 1999, seventeen patients, 10 males and 7 females, mean age 66 years (standard deviation +/- 4) were examined after total knee arthroplasty. Exclusion criteria were prosthesis loosening and severe (equal or superior to 7 degrees) varus or valgus deviation. All patients were examined with knee radiography in the standing position completed by axial projections of patella and by CT scanning. We used a modification of Berger technique and carried out comparative CT scans extended lower limbs and acquisitions perpendicular to the mechanical axis of the knee, from the femoral supracondylar region down to the plane crossing the distal end of the tibial prosthetic component. Reference lines were then drawn electronically on given scanning planes to reckon the axial deviation of the femoral and tibial prosthetic components.
Six patients, one female and 5 males, with normal rotational values of femoral and tibial prosthetic components presented no clinical symptoms. Eight patients, 4 females and 4 males, with abnormal values presented the following clinical symptoms: medial impingement, (incomplete) dislocation patella, and lateral instability. One female patient with a normal rotational value of femoral prosthetic component and an altered value of tibial prosthetic component presented medial impingement. Finally two patients, one female and one male, were absolutely asymptomatic although the rotational values of the two prosthetic components were beyond the normal range.
Total knee arthroplasty is presently a standard treatment for many conditions involving this joint. There are several possible postoperative complications, namely fractures, dislocations (a)septic loosening and femoropatellar instability. The latter condition is the most frequent complication among implant failures and is caused by bad orientation of the femoral and tibial components on frontal and axial planes. We measured the orientation of the prosthetic components introducing a CT procedure which modifies the uniarticular with four scans introduced by Berger. The new method uses Berger's parameters and the CT study of both joints by means of Helical CT. With a single examination lasting less than 4 minutes and with the patient in a more comfortable position, we can obtain: 1) comparative and simultaneous assessment of the contralateral joint; 2) several scans to better define Berger's parameters and to accomplish measurement of the rotational deviation with higher precision and markedly decreasing the error margin. The analysis of the results confirms the international literature findings and especially the fundamental importance in positioning both prosthetic components within normal values, as emphasized by the relationship between the clinical symptoms and the rotational degree of the femoral and tibial prosthetic components.
通过CT评估全膝关节置换术中股骨和胫骨假体组件的轴向偏差。
1999年1月至7月，对17例全膝关节置换术后的患者进行了检查，其中男性10例，女性7例，平均年龄66岁（标准差±4）。排除标准为假体松动以及严重（等于或大于7度）的内翻或外翻偏差。所有患者均进行了站立位膝关节X线摄影，包括髌骨的轴向投影，并进行了CT扫描。我们采用了对Berger技术的改良方法，对下肢进行了对比CT扫描，并从股骨髁上区域向下至穿过胫骨假体组件远端的平面进行垂直于膝关节机械轴的采集。然后在给定的扫描平面上电子绘制参考线，以计算股骨和胫骨假体组件的轴向偏差。
6例患者（1例女性和5例男性）股骨和胫骨假体组件的旋转值正常，无临床症状。8例患者（4例女性和4例男性）旋转值异常，出现以下临床症状：内侧撞击、（不完全）髌骨脱位和外侧不稳定。1例女性患者股骨假体组件旋转值正常，胫骨假体组件旋转值改变，出现内侧撞击。最后，2例患者（1例女性和1例男性）虽然两个假体组件的旋转值超出正常范围，但完全没有症状。
全膝关节置换术目前是许多累及该关节疾病的标准治疗方法。术后有几种可能的并发症，即骨折、脱位、（感染性）松动和髌股关节不稳定。后一种情况是植入物失败中最常见的并发症，是由股骨和胫骨组件在额面和轴面上的不良定向引起的。我们通过引入一种CT程序来测量假体组件的定向，该程序对Berger提出的单关节四次扫描方法进行了改进。新方法采用了Berger的参数，并通过螺旋CT对两个关节进行了CT研究。单次检查持续时间不到4分钟，且患者处于更舒适的体位，我们可以获得：1）对侧关节的对比和同步评估；2）多次扫描以更好地定义Berger参数，并以更高的精度完成旋转偏差测量，显著降低误差范围。结果分析证实了国际文献的研究结果，特别是强调了将两个假体组件定位在正常值范围内的根本重要性，这一点从临床症状与股骨和胫骨假体组件旋转程度之间的关系中可以看出。
