膝关节骨性关节炎患者下肢扭转角度CT评价的临床价值

目的 探讨膝关节骨性关节炎患者膝扭转角及胫骨扭转角的CT测量方法,为人工全膝关节置换术中人工假体相对旋转定位提供可靠的参考径线,判断以胫骨结节内1/3作为胫骨假体旋转定位的骨性标志时,股骨假体和胫骨假体的旋转对线情况,并探讨术后CT测量扭转角的可行性.方法 对34例(68膝)拟行人工全膝关节置换术的膝关节骨性关节炎患者,于术前行伸膝旋转中立位CT扫描,测量膝关节股骨后髁角,手术前后膝扭转角、胫骨扭转角,并测量股骨上髁轴中点C与髌韧带内1/3点连线(BC)和经股骨上髁轴中点C的垂线(AC)之间的夹角,即α角.结果 全组病例股骨后髁角为0～7.5°,中位数为2.36°±7.5°)；全组病例内翻畸形57例膝关节α角为10.85°±10.47°(0°±28.1°)；外翻畸形7个膝关节,α角为11.6±7.3°(-6.5°±26.8°).全组病例术前膝扭转角,左膝:10.72°±7.81°,右膝:9.58°±5.84°.胫骨扭转角,左侧:27.68°±10.26°,右侧:28.14°±10.89°.结论 ①CT成像技术测量下肢扭转角度是一种准确、客观、可重复性的测量方法,具有重要的临床应用价值.②利用CT成像技术可以为人工全膝置换术中人工假体相对旋转定位提供可靠的参考径线.③在人工全膝关节置换术中,采用传统的以胫骨结节内中1/3点作为胫骨假体的参考标志是造成假体间不匹配的主要原因.④CT成像技术测量术后膝扭转角度可作为术后评价疗效和跟踪随访的可靠途径之一.

Clinical value of computed tomography on evaluating lower extremity rotation of osteoarthritic patient

Objective To investigate the method of measuring the torsion angle of knee and tibia by CT in osteoarthritic patients and to determine the accuracy of using the medial 1/3 of the tibia] tuberosity as the reference line in total knee arthroplasty. Methods From July 2010 to January 2011,34 patients （2 men, 32 women; age range： 61-79 years, average 70.5 years） with 68 osteoarthritic knees underwent CT before total knee arthroplasty. With the knees in extension and no rotation, the torsion angles of knees and tibiae, the posterior condylar angles （PCA） between the lines of surgical epicondylar axes （SEA） and posterior condylar axes, and the α angles were measured. The α angle was an angle measured between the line drawn on the SEA of the femur and the medial 1/3 of the tibial tuberosity and was defined as the rotational mismatch. Results Of 68 knees, 57 varus deformities were found with PCA of 2.360±7.5° （0° to 7.5°） and ot angles of 10.85°±10.47°（0° to 28.1°）. There were 7 valgus deformities with ct angles of 11.6°±7.3° （-6.5° to 26.8°）. In 30/68 knees （49%）, the ot angles were greater than 10°, 8 of which greater than 20°. The torsion angles of the knees were 10.72°±°7.81° on the left and 9.580°±5.84° on the right. The torsion angles of tibiae were 27.68°±°10.26° on the left and 28.14°±°10.89° on the fight. Conclusion CT measurements of torsion angles, PCA and α angles are accurate, objective and reproducible for evaluating lower extremity rotation. In total knee arthroplasty, the medial 1/3 of the tibial tuberosity is unreliable as a rotational landmark.