Distal femoral rotational axis reference method based on magnetic resonance technique

Lv Guo-yi; Li Zhen-xu; Xiang Xu; Li Jian-ling; Yin Jie

doi:10.3969/j.issn.2095-4344.2016.26.018

Abstract：BACKGROUND:Problems regarding the prosthesis in the horizontal plane and the rotation of the femur and tibia prosthesis on line are relatively weak. The distal femoral rotation axis is mainly the transepicondylar axis. Due to patient differences as wel as anatomy and intraoperative display, it is difficult to accurately locate the axis in the process of knee arthroplasty. OBJECTIVE:To investigate application of magnetic resonance technique in determining the axis of rotation of the distal femur, to provide reference and basis for femoral rotational alignment during total knee arthroplasty. METHODS:Data of 122 cases without knee joint disease, who were diagnosed and treated in the Department of Orthopedics of Nanyang City Center Hospital from September 2014 to October 2015, were analyzed. Magnetic resonance technique was used to measure femoral epicondyle axes (STEA), femoral epicondyle axes (CTEA), the anteroposterior axis (APL) and femoral shaft (PCL). Simultaneously, magnetic resonance technique was utilized to measure femoral ankle angle (PCA), ankle twist angle (CTA), axis vertical line and ankle axis angle (PAPA). Each data were tested three times, and the average value was calculatd. We analyzed the method of magnetic resonance technique to determine reference axis of distal femoral rotation. RESULTS ANDCONCLUSION: (1) Accuracy of the angle close to surgical transepicondylar axis: 3° PCL> CTEA > APL verticalline. (2) No significant difference in PCA was detected in two sets of measurements (P> 0.05). CTA and PAPA parameters in the first measurement by magnetic resonance imaging diagnosis were significantly lower than the second measurement (P< 0.05). (3) Results indicate that magnetic resonance technology provides ideal reference for distal femoral rotation, can accurately measure the CTA, PCA, PAPA andother indicators. It is a more reliable determination method and can be used in scientific determination of femoral rotational alignment reference axis in total knee arthroplasty. Except STEA, the accuracy of 3° PCL is highest.