【作者】 赵宝辉；

【导师】 陈百成；

【作者基本信息】 河北医科大学 ， 外科学， 2009， 博士

【摘要】 1股骨远端旋转对线参考轴线与胫骨机械轴关系的研究目的:正确的股骨假体旋转对线是全膝关节表面置换术成功的重要因素。股骨假体的旋转对线可影响全膝关节置换术的疗效。股骨假体的旋转对线对髌骨的运动轨迹和屈膝间隙的平衡有着巨大的影响,而屈膝间隙的平衡又可以影响胫–股关节运动轨迹。用以确定股骨假体旋转对线的标志有Whiteside线、经股骨髁上轴、股骨后髁轴等。本研究通过对下肢尸体标本上各轴线的测量,比较各轴线与下肢机械轴的关系,确定较为理想的股骨假体的旋转对线参考标志并对其生物力学优越性进行探讨。方法:30例下肢尸体标本,其中左下肢12例,右下肢18例,性别及年龄不明。所有标本均无解剖畸形,膝关节无骨关节炎、无前后交叉韧带及侧副韧带损伤等关节疾病。切除下肢所有软组织及髌骨,保留膝关节内外侧副韧带、前后交叉韧带、内外侧半月板及部分关节囊,经踝关节离断。在前交叉韧带重建定位器械引导下,将两枚2.0mm克氏针分别穿过股骨远端,一枚经股骨外侧髁最高点至内侧髁最高点,代表临床髁上轴;一枚经股骨外侧髁最高点至股骨内上髁凹,代表外科髁上轴。数码相机距下肢80cm处,视线方向与胫骨垂直,前方对准膝关节中心。分别在膝关节伸直位、屈膝90°进行数码照片采集,伸直位照片近端包括股骨头,远端包括胫骨内踝,屈膝90°位近端包括股骨前方皮质,远端包括胫骨内踝。照片输入笔记本电脑,并经Adobe Photoshop CS软件进行图像处理。参照Moreland的方法确定股骨头中心、膝关节中心、踝关节中心。股骨机械轴:股骨头中心与膝关节中心的连线。胫骨机械轴:膝关节中心与踝关节中心的连线。下肢机械轴:股骨头中心与踝关节中心的连线。Whiteside线为股骨滑车最低点与髁间窝最高点连线。利用Adobe Photoshop CS软件在各图像上画出各轴线,并测量各轴线间夹角。上述工作均由3名研究者同时完成,股骨远端解剖标志和各轴线的确定须3名研究者意见达成一致时方可确定。在伸膝位图像上测量股骨机械轴与胫骨机械轴的夹角,临床髁上轴、外科髁上轴和Whiteside线的垂线与胫骨机械轴的夹角;屈膝90°时测量临床髁上轴的垂线、外科髁上轴的垂线和Whiteside线与胫骨机械轴的夹角,测量结果精确到0.1°,相对于胫骨机械轴内翻记录为正值,外翻记录为负值。将股骨机械轴与胫骨机械轴的夹角与屈膝90°时测得的临床髁上轴的垂线、外科髁上轴的垂线和Whiteside线与胫骨机械轴的夹角相比较,并比较膝关节伸直与屈曲时临床髁上轴、外科髁上轴和Whiteside线的垂线旋转差异。统计学方法采用Wilcoxon秩和检验,P<0.05有统计学意义。结果:胫骨机械轴与临床髁上轴的垂线、外科髁上轴的垂线、Whiteside线、股骨机械轴夹角的范围分别是:–4.7°~7.0°、0.3°~11.0°、–10.4°~10.7°、–2.8°~8.3°。其均数±标准差分别为0.6°±3.0°、3.9°±2.7°、–0.2°±4.8°、3.0°±3.0°。临床髁上轴、外科髁上轴、Whiteside线的垂线在伸、屈膝时相对于胫骨机械轴夹角差异范围分别为:–12.0°~4.1°、–7.8°~7.6°、–18.7°~6.8°0。其均数±标准差分别为:–2.3±3.8°、0.9±3.6°、–3.1±5.5°。股骨机械轴和胫骨机械轴的夹角大于临床髁上轴的垂线和胫骨机械轴的夹角,两者比较有统计学意义(P<0.05),胫骨机械轴和股骨机械轴的夹角大于Whiteside线和胫骨机械轴的夹角,两者比较有统计学意义(P<0.05),而股骨机械轴和胫骨机械轴的夹角与外科髁上轴垂线和胫骨机械轴的夹角相比较,差异无统计学意义(P>0.05)。小结:本研究通过对下肢尸体标本的研究,分析股骨远端旋转对线各参考标志与胫骨机械轴关系,通过与以往的研究方法相比较,这一方法准确可靠。通过研究发现,外科髁上轴的垂线和胫骨机械轴的夹角与股骨机械轴和胫骨机械轴的夹角间的差异最小。外科髁上轴是较临床髁上轴、Whiteside线更为可靠的股骨假体旋转对线参考标志,当股骨后髁切骨与外科髁上轴平行时,可获得较为理想的股骨假体外旋位置,对髌–股关节和胫–股关节运动轨迹的不良影响最小。然而,因为个体间股骨解剖变异存在,选择外科髁上轴作为股骨假体旋转对线参考标志,仍会发生一定程度的伸屈膝间隙不平衡,需通过术中适当的软组织松解予以纠正。2胫骨近端假体旋转对线参考标志的影像学研究目的:股骨和/或胫骨假体旋转对线是影响全膝关节置换术后膝关节功能和假体生存率的重要因素。二者间的旋转对线不匹配可影响髌–股关节运动轨迹和功能,还可导致胫–股关节半脱位、聚乙烯衬垫磨损的加速和碎裂。通过第一部分的研究发现,股骨假体外旋对线参考股骨外科髁上轴线具有生物力学优越性可以最大程度恢复膝关节功能。但是胫骨假体旋转对线参考轴线还存在争议,关节内的解剖学标志如胫骨后髁轴线、经胫骨髁上轴线、胫骨髁间脊间沟都被用作胫骨假体旋转对线参考轴线。然而,因为骨赘形成、骨质缺损和解剖学变异,术中很难在截骨平面准确判定这些解剖标志。胫骨结节内侧1?3常被用作胫骨假体的旋转对线的参考标志,但这一方法没有实验依据,且可导致胫骨假体过度外旋。有学者建议髌韧带止点处内侧缘作为胫骨假体的旋转对线的参考标志。本研究通过比较胫骨结节内侧1?3、髌韧带止点处内侧缘作为胫骨假体旋转对线参考标志相对于股骨外科髁上轴线差异程度,分析二者作为胫骨假体旋转对线参考标志的优劣。方法:对15名健康志愿者的膝关节行CT扫描检查。试验对象仰卧,双膝并拢,膝关节完全伸直,足趾朝上,CT扫描平面与胫骨干的解剖轴垂直。扫描范围近侧包括股骨髁近端,远侧包括胫骨结节下缘。所获CT扫描图像输入个人计算机。选择每例膝关节的两幅图像:股骨侧CT扫描图像能显示股骨外侧髁最高点和股骨内上髁凹,胫骨侧CT扫描图像选自经外侧胫骨平台下方10mm的图像(术中胫骨切骨平面)。用专用医学影像学Dicom viewer图像分析软件对CT扫描图像进行分析和测量,在股骨侧CT扫描图像画出股骨外科髁上轴线(经股骨外侧髁最高点至股骨内上髁凹),并测量与图像横轴的夹角γ。在胫骨侧CT扫描图像画出股骨外科髁上轴线的垂线(此垂线与图像纵轴的夹角等于经股骨髁上轴线与图像横轴的夹角γ),并在胫骨侧CT扫描图像画出胫骨二前后轴线(后交叉韧带止点中点与髌韧带止点处内侧缘连线和后交叉韧带止点中点与髌韧带内中1/3连线,因髌韧带较胫骨结节更易辨别测量),测量二胫骨前后轴线与股骨外科髁上轴线的垂线夹角。上述分析测量工作均由3名研究者同时完成,各解剖标志和轴线的确定须3名研究者意见一致。夹角测量结果精确到0.1°。二胫骨前后轴线相对于股骨外科髁上轴的垂线内旋记录为正值,外旋记录为负值。统计学方法采用t检验,分别比较二胫骨前后轴线相对于股骨外科髁上轴的垂线的旋转差异和二胫骨前后轴线间的差异,P<0.05有统计学意义。结果:1例女性志愿者右膝关节CT平扫检查发现髌骨外倾,3例膝关节CT扫描图像未能清晰辨别股骨内上髁凹或股骨外侧髁最高点和股骨内上髁凹不能同时显示,经研究组讨论而未被纳入本研究。最终获得26例膝关节CT扫描图像。后交叉韧带止点中点与髌韧带止点处内侧缘连线与股骨外科髁上轴垂线的走行方向最为接近,二者间夹角为0.7°±2.8°(范围:?5.1°~5.8°),与股骨外科髁上轴线垂线的平行线,即与股骨外科髁上轴线垂线的平行线(夹角0°)相比较,差异无统计学意义(P>0.05);后交叉韧带止点中点与髌韧带内中1/3连线与股骨外科髁上轴垂线的夹角为6.9°±5.3°(范围:?3.4°~14.1°),与股骨外科髁上轴线垂线的平行线,即与股骨外科髁上轴线垂线的平行线(夹角0°)相比较,差异有统计学意义(P<0.05)。两线间走行方向差异较大,后交叉韧带止点中点与髌韧带止点处内侧缘连线与股骨外科髁上轴的垂线近乎平行,而后交叉韧带止点中点与髌韧带内中1/3连线相对于股骨外科髁上轴线垂线有较大外旋,二胫骨前后轴线比较,差异有统计学意义(P<0.05)。小结:本研究通过比较胫骨结节内侧1?3、髌韧带止点处内侧缘与第一部分研究结果所确定的股骨远端旋转对线参考轴线即外科髁上轴比较,分析二者间的差异,后交叉韧带止点中点与髌韧带止点处内侧缘连线与股骨外科髁上轴线垂线的走行方向最为接近,选择后交叉韧带止点中点与髌韧带止点处内侧缘连线作为胫骨假体旋转对线的参考轴线可使股骨与胫骨假体间的旋转匹配关系更为理想。可以优化髌–股关节与胫股关节运动轨迹,降低并发症发生率。虽然这样,TKA术后膝关节的运动学已不同于正常膝关节,所有的研究只能部分恢复膝关节功能。在本研究中,虽然后交叉韧带止点中点与髌韧带止点内侧缘连线与股骨外科髁上轴线垂线间夹角平均为外旋0.7°,但是仍有部分受试者后交叉韧带止点中点与髌韧带内侧缘连线与股骨外科髁上轴线垂线呈现较大夹角(最大内旋5.1°,最大外旋5.8°)。因此,术中也可结合自定位法,对胫骨假体旋转位置做出适当调整。3膝关节股骨后髁偏置距与胫骨后倾角关系对屈膝功能的影响目的:全膝关节表面置换术不足之处是不能全部恢复正常膝关节的屈膝范围。在屈膝终末时,股骨后方皮质与胫骨假体后缘发生撞击,从而限制膝关节的继续屈曲。切骨后恢复胫骨后倾角度被认为可延迟撞击的发生;膝关节最大屈曲角度与股骨后髁偏置距大小相关,认为股骨后髁偏置距在延迟撞击中具有重要的作用。手术技术的使用,尤其是切骨方法可影响术后股骨后髁偏置距和胫骨后倾角度的大小,从而影响膝关节屈膝范围。在正常膝关节,尽管存在着种族、性别及个体间的解剖学差异,但是都能达到良好的屈膝范围。本研究目的测量正常膝关节股骨后髁偏置距和胫骨后倾角度的大小,并分析二者之间的相关性及与膝关节屈曲范围的关系。方法:摄取15位健康成年志愿者的膝关节侧位平片,照片包括远端1/3股骨和近端2/3胫骨,且使股骨内外侧髁重叠。所获膝关节侧位X平片输入个人电脑。因照片放大率不同,所测得的股骨后髁偏置距绝对值也不具可比性,因此在本研究中,我们测量股骨后髁偏置距与股骨远端直径的比值,称之为相对高度,将此值与胫骨平台后倾角相比较。用DicomViewer图像分析软件在图片上画出所需各线,沿股骨后侧皮质画出线A;线A与股骨远端后侧远端皮质相交,自此交点画垂线B,前方止于股骨前侧皮质,B为股骨远端直径;自股骨内侧髁后方最高点画线A的垂线C,线C为股骨后髁偏置距的高度。测量线C与线B的比值Z, Z为股骨后髁偏置距的相对高度,Z值越大股骨后髁向后凸出越明显。在胫骨近段任意画出两线连接胫骨前后侧皮质,在连接两线中点画出胫骨近段解剖轴线D,向近端延伸达胫骨平台。沿胫骨内侧平台关节面画线E,测量二者之间的夹角θ,以90°减去θ即为胫骨平台后倾角α。上述分析测量工作均由3名研究者同时完成,各解剖标志和轴线的确定须3名研究者意见一致。统计学方法采用Pearson相关性分析检验股骨后髁偏置距大小与胫骨平台后倾角二者间有无相关性,P<0.05有统计学意义。结果:所有志愿者膝关节均能完成下蹲,下跪时足跟部都能与臀部相接触,经DR平片检查未发现膝关节内外翻畸形,无异常关节间隙狭窄、软骨下骨硬化、囊性边、骨赘形成等骨关节炎征象,无任何骨肿瘤样改变征象,骨骺均已闭合。其中5例DR平片因不符合测量要求(股骨髁未重叠)未纳入本研究。经测量胫骨平台后倾角平均为12.03(°标准差:3.74°,范围:5.11°~20.54°),股骨后髁偏置距与股骨远端直径的比值平均为0.95 (标准差:0.24,范围: 0.695~1.236),胫骨平台后倾角与股骨后髁偏置距和股骨远端直径的比值无相关性(R2=0.017)。小结:本研究通过对正常膝关节研究未发现股骨后髁偏置距与胫骨后倾角二者间存在相关性,二者大小变异也较大。尽管如此,TKA术后的运动学研究发现股骨后髁偏置距与胫骨后倾角在延迟撞击增加屈膝范围中起着重要的作用,因此在全膝表面置换术中,在股骨后可切骨时,除考虑股骨假体外旋对线,应尽量恢复股骨后髁偏置距,使完成股骨后髁切骨假体安装后的股骨后髁偏置距与股骨远端(股骨后方皮质与其远端弧形相切处)直径相等(0.95),尽管我们的研究结果胫骨平台后倾角平均为12.03°,但考虑到胫骨平台后倾角过大后假体衬垫后方所受应力过大,是伸膝装置紧张,而且我们的研究结果存在的抽样误差,综合其他学者的研究结果,我们建议切骨胫骨平台后倾角应保持10°后倾。正常膝关节在屈伸活动时,胫骨与股骨间的运动方式受诸多因素的影响,除外股骨远端和胫骨近段骨骼形态对胫骨与股骨间的运动方式的影响,需对交叉韧带张力变化如何引导胫骨与股骨间的运动,半月板的活动方式如何适应胫骨与股骨间的运动作进一步研究。不但对全膝置换术假体设计、手术方法改进意义重大,而且对膝关节创伤重建、交叉韧带损伤重建、胫骨高位截骨术这些对膝关节运动学造成影响的手术方法提供理论依据。更多还原

【Abstract】 1. A Cadaveric Study of Relationships among Rotational Alignment Reference Axes of Distal Femur and Tibial Mechanical AxisObjective: Correct rotational alignment of the femoral component is one of the most important factors for successful total knee arthroplasty. Patellar tracking and ligament balance in flexion are affected by the rotational alignment of the femoral component; the imbalance of the flexion gap can also affect the tracking of tibial–femoral joint. The rotational position of the femoral component can be determined using bony landmarks, such as the transepicondylar axis, the posterior condylar axis, or the Whiteside’s line. The current study was to investigate the relationships among rotational alignment reference axes of distal femur and tibial mechanical axis, determine the safest rotational alignment reference axis,and discuss its biomechanical advantages.Method: Thirty cadaveric lower extremities obtained from the anatomical department were studied. There were twelve left lower extremities, eighteen right lower extremities. The gender and age of the cadaveric lower extremities were unknown. None of the specimens had gross deformities, no osteoarthritis, the medial and lateral collateral ligaments, the anterior and posterior cruciate ligament, the medial and lateral meniscus were all intact. Skin, muscles, excess soft tissues, patella and the anterior part of the knee capsule were removed from each lower extremity, whereas collateral ligaments and intra-articular structures (the anterior and posterior cruciate ligament, the medial and lateral meniscus) were left intact.Guided by an ACL cannulated drill–aiming jig, 2 pieces of Kirschner wire (2mm in diameter) were drilled through each distal femur. One passed through the lateral epicondylar prominence and the most prominent point of the medial epicondyle, represented the clinical epicondylar axis, the other one passed through the lateral epicondylar prominence and the medial sulcus of the medial epicondyle, represented the surgical epicondylar axis.Digital camera was fixed 80cm anteriorly from lower extremity with the visual axis perpendicular to the tibial axis, and focused to the center of the knee. Digital photos were taken with knee in extension and flexion at 90°, photos include femoral head proximally and medial malleolus distally with knee in extension. When the photos were taken with knee in flexion at 90°, anterior femoral cortex and medial malleolus were included.Digital photos were inputted to the personal computer, the radiographic measurements were performed using Adobe Photoshop CS Image processing software. The femoral mechanical axis was defined as the line connecting the center of the femoral head and the center of the knee, whereas the mechanical axis of the tibia was defined as the line connecting the center of the knee and the center of the talus. Angles were measured among tibial mechanical axis and a line perpendicular to clinical epicondylar axis, a line perpendicular to surgical epicondylar axis, Whiteside’s line and femoral mechanical axis, positive value implied the line measured varus relative to the tibial mechanical axis, whereas negative value implied valgus. Statistical analysis was performed using SPSS 11.0, and Wilcoxon signed rank test was used.Results: The angles among the tibial mechanical axis and a line perpendicular to the clinical epicondylar axis, a line perpendicular to the surgical epicondylar axis, Whiteside’s line, and femoral mechanical axis were–4.7°~7.0°, 0.3°~11.0°,–10.4°~10.7°,–2.8°~8.3°respectively, the mean and standard deviation were 0.6°±3.0°, 3.9°±2.7°,–0.2°±4.8°, 3.0°±3.0°respectively. The difference of angles among the tibial mechanical axis and the clinical epicondylar axis, the surgical epicondylar axis, and a line perpendicular to Whiteside’s line between knee extension and knee flexion was–12.0~4.1°,–7.8°~7.6°,–18.7°~6.8°respectively, the mean and standard deviation were–2.3±3.8°, 0.9±3.6°,–3.1±5.5°respectively. The angle between the femoral mechanical axis and the tibial mechanical axis was significantly larger than the angle among the tibial mechanical axis and a line perpendicular to the clinical epicondylar axis, the Whiteside’s line (p<0.05).There was no significant difference compared with the angle between a line perpendicular to the surgical epicondylar axis and the tibial mechanical axis and the angle between the femoral mechanical axis and the tibial mechanical axis (p>0.05).Conclusion: The surgical epicondylar axis rather than the clinical epicondylar axis or the Whiteside’s line can maintain a more predictable orientation with respect to the tibial mechanical axis when moving from flexion into extension; however, a certain amount of gap imbalance between flexion and extension can occur because of anatomic variations, a certain amount of ligamentous release still will be necessary.2. Radiographic Study of Tibial Component Rotational Alignment Reference Landmarks of the Proximal TibiaObjective: The rotational relationship between the femoral and tibial components is an important factor affecting the overall function and durability of a total knee arthroplasty. Malalignment of the femoral and/or tibial component has been associated with patellofemoral complications such as tilting, subluxation, dislocation, accelerated wear, loosening, and fracture. The surgical epicondylar axis has been established as the optimal rotational alignment reference for femoral component in the current study. Several reference techniques for establishing tibial rotational alignment have been proposed, such as the posterior condylar line of the tibia plateau, the transcondylar line of the tibia and the midsulcus line of the tibial spine. However, these axes may be difficult to determine intraoperatively given the osteophytes, bone loss, anatomic variation, and deformity seen at the proximal tibia in this patient population. Aligning the tibial component with the medial 1/3 of the tibial tubercle has been stated to maximize function. This may have been established empirically, because there was no theoretical background of this technique. Furthermore, it has been reported that aligning the tibial component with the medial 1/3 of the tibial tubercle will result in excessive external rotation in some cases. The medial border of the patellar tendon attachment was also proposed as a rotational alignment reference for tibial component. This study was to compare the difference between the two anatomical references relative to the surgical epicondylar axis, and evaluate its’reliability for tibial component rotational alignment.Method: Fifteen healthy volunteers were enrolled in this study. Each knee was performed CT scanning. During scanning, the volunteers lied down in a supine position, with both knees in full extension and put together closely, the toes pointed upward. Transverse CT scans of each knee were obtained, ranging from femoral condyle proximally to the tibial tubercle distally. All the CT scan images were inputted to the personal computer, two of the CT scan images of each knee were selected for measurement, the femoral side CT scan image on which the lateral epicondylar prominence and the medial sulcus of the medial epicondyle could be recognized, the tibial side CT scan image is the one that passed through 10 mm distal to the lateral tibial plateau (the cutting surface of the tibia when perform the primary TKA). The selected CT scan images were analyzed and measured using the professional medical image processing software Dicomviewer. The surgical epicondylar axis was defined as a line connecting the most prominent point of the lateral femoral epicondyle and the deepest point of the sulcus of the medial femoral epicondyle. On the femoral side CT scan images, the most prominent point of the lateral femoral epicondyle and the deepest point of the sulcus were determined on the software, a line was drawn connecting the two anatomical landmarks. The angle (γ) between the surgical epicondylar axis and the transverse axis of the image was also measured. On the tibial side CT scan images, a line perpendicular to the surgical epicondylar axis was drawn, the angle between this line and the longitudinal axis of the image equaled to the angle between the surgical epicondylar axis and the transverse axis of the image. Two anteroposterior axis (AP and AP’) of the tibia in an extended knee position, a line that connecting the medial border of the patellar tendon and the middle of the posterior cruciate ligament insertion and a line that connecting the medial 1/3 of the patellar tendon and the middle of the posterior cruciate ligament insertion, were drawn on the tibial side CT scan images. Because the patellar tendon could be more clearly identified than the tibial tubercle, we used the medial 1/3 of the patellar tendon to represent the 1/3 of the tibial tubercle in this study. The angles were measured between the two tibial anteroposterior axes and a line perpendicular to the surgical epicondylar axis. All the measuring procedures were performed by three researchers in our study group together in a same time, and all anatomic landmarks and reference axes were determined by three researchers with consensus. The accuracy of measurement value of each angle was 0.1°. Positive value indicated the tibial anteroposterior axis was in an internal rotation position relative to the line perpendicular to the surgical epicondylar axis, whereas the negative value indicated the tibial AP axis was in an external rotation position relative to the line perpendicular to the surgical epicondylar axis. The statistical analysis was performed using student’s t test, the software used was SPSS 11.0, and probability values less than 0.05 were considered statistically significant.Results: One right knee of a female volunteer with lateral subluxation of the patella observed on the CT scan, three knees which the most prominent point of the lateral femoral epicondyle and the deepest point of the sulcus of the medial femoral epicondyle could not be clearly identified or could not be identified in a same CT scan image, were excluded from the study. Finally, twenty–six CT scan images of the knees were measured in this study. The mean angle between the line that connecting the medial border of the patellar tendon and the middle of the posterior cruciate ligament insertion and the line perpendicular to the surgical epicondylar axis was 0.7°±2.8°, ranging from ?5.1°to 5.8°, there was no significant difference between the two lines(P>0.05). The mean angle between the line that connecting the medial 1/3 of the patellar tendon and the middle of the posterior cruciate ligament insertion was 6.9°±5.3°, ranging from ?3.4°to 14.1°, there was significant difference between the two lines(P<0.05). The line that connecting the medial border of the patellar tendon and the middle of the posterior cruciate ligament insertion was approximately parallel to the line perpendicular to the surgical epicondylar axis, whereas the line that connecting the medial 1/3 of the patellar tendon and the middle of the posterior cruciate ligament insertion was comparatively external rotational relative to the surgical epicondylar axis, there was significant difference between the two tibial AP axis (P<0.05).Conclusion: The current study compared the relationships between the tibial reference land marks, the medial border of the patellar tendon, he medial 1/3 of the patellar tendon, and the surgical epicondylar axis, the results indicated that the line that connecting the medial border of the patellar tendon and the middle of the posterior cruciate ligament insertion was approximately parallel to the line perpendicular to the surgical epicondylar axis, when aligning the tibial component with the medial border of the patellar tendon, there would be an ideal rotational alignment relationship between the femoral and tibial component, optimizing the patellofemoral joint and femur–tibial joint tracking, maximizing the postoperative knee function. In the current study, although the line that connecting the medial border of the patellar tendon and the middle of the posterior cruciate ligament insertion was in an average 0.7°external rotation relative to the line perpendicular to the surgical epicondylar axis, there were comparatively large angles between the he line that connecting the medial border of the patellar tendon and the middle of the posterior cruciate ligament insertion (the maximal internal rotation was 5.1°, the maximal external rotation was 5.8°). Therefore, when aligning the tibial component with the medial border of the patellar tendon, the surgeon should combine using the self alignment method to appropriately adjust the position of the tibial component.3. Measurement of the posterior condylar offset and the posterior tibial slope of normal knees and the influence of its relationship to the flexional functionObjective: At deep knee flexion postoperatively, the mobility is limited by the impingement occurring between the posterior femoral cortex and the posterior borders of the tibial plateaus. The restoration of the posterior tibial slope has been shown to delay the tibial–femoral impingement. Studies have shown that the maximal knee flexion relative to the posterior condylar offset, which was important factor in delaying the tibial–femoral impingement. The surgical techniques, especially the cutting method, could affect the posterior condylar offset and the posterior tibial slope. Thus, carefully planned bone cuts may increase the range of flexion obtained before impingement occurs and thus substantially improve knee flexion range. Although there are anatomical differences of normal knees in race, gender and individual, each normal knee can reach the ideal flexion angle. The current study was to measure the posterior condylar offset and the posterior tibial slope of the normal knees and analyze the influence of its relationship to the flexional function.Method: A true lateral radiograph of thirty knees of fifteen healthy adult volunteer were obtained for measurement. To derive an accurate and reliable measurement of the posterior tibial slope and the posterior condylar offset, the radiograph should include 1/3 of the distal femur, 2/3 of the proximal tibial with the femoral condyles superimposed. All the lateral radiographs were inputted into the personal computer, analyzing and measurement of the lateral radiograph were performed using professional medical image processing software (Dicom viewer). The posterior condylar offset was defined as the maximal height of the posterior condyle which projected posteriorly to the tangent of the posterior cortex of the femoral shaft. For the difference of magnification among radiographs, there was no comparability among measurements of the absolute value of the posterior condylar offset. For this reason, we measured the relative value of the posterior condylar offset relative to the diameter of the distal femur, without any error from small differences in magnification between the individual radiographs, and compared this relative value of the posterior condylar offset with the posterior tibial slope. Lines were drawn on the lateral radiograph using software Dicomviewer. Line A was drawn tangential to the posterior cortex of the femur, line A intersected with distal posterior cortex of the femur. From this intersection, line B was drawn perpendicular to line A anteriorly reaching the anterior cortex of the femur, representing the diameter of the distal femur. Line C was a vertical line of line A drawn from the most posterior point of the medial posterior condylar, representing the height of the posterior condyle. Quotient Z was determined by dividing the condylar height (C) by the diameter of the distal femur (B). Z describes the relation between the condylar height and the diameter of the distal femur. The larger Z value indicates more posterior prominent of femoral condyle. The posterior tibial slope defined as the angle between the line perpendicular to the proximal tibial anatomical axis and the tangent line of the medial tibial plateau. the proximal tibia anatomical axis D was drawn as a line connecting midpoints of two lines which were drawn randomly connecting the anterior and posterior cortex of the proximal tibia, line D extended proximally passing though the medial tibial plateau. Line E was then drawn parallel to the articular surface of the medial tibial plateau. The angleθwas measured between line D and line E, the posterior tibial slope angleαequals 90°subtractsθ. positive slope values corresponded to a posterior slope, and Negative slope values corresponded to an anterior slope. All the measuring procedures were performed by three researchers in our study group together in a same time, and all anatomic landmarks and reference axes were determined by three researchers with consensus. The precise of measurement value of each angle was 0.1°. Pearson’s correlation test was used for correlation evaluations between the posterior condylar offset and the posterior tibial slope. P values less than 0.05 were regarded as statistically significant.Results: All the knees included in this study could accomplish squatting; the heel could reach the buttocks when kneeling on the ground. There were no varus or valgus deformities in the knee joints observed on radiographs. There were no signs of ostarthritis, such as narrowing of joint space, subchondral bone sclerosis, subchondral cyst, osteophytes formation. There were no signs of bone tumor. Skeletal growths were all completed. Five radiographs did not correspond to the measuring criterion were exclude from the study because of the both condyle were not superimposed. The mean posterior slope of the medial tibia plateau with reference to the proximal tibia anatomical axis was 12.03°. The degree of posterior tibial slope varied widely among the subjects, ranging from 5.11°to 20.54°. The mean relative height of the medial posterior condylar was 0.95, ranging from 0.695 to 1.236. There was no correlation found between the posterior tibial slope and the relative height of the medial posterior condylar (R2=0.017).Conclusion: There was no correlation found between the posterior tibial slope and the relative height of the medial posterior condylar in the current study, the degree of posterior tibial slope and the relative height of the medial posterior condyle also varied widely among the subjects. In spite of these findings, postoperative TKA knee kinematic studies have shown that the posterior tibial slope and the posterior condylar offset play an important role in delaying the tibial-femoral impingement to maximizing the knee flexion function, therefore, when performing the posterior condylar cut, pay attention not only the rotational alignment of femoral component, but also to maintain the posterior condylar offset equals to the diameter of the distal femur(the point that posterior femoral cortex tangential to the curve proximal to the posterior condyle ) after the posterior condylar cut has been accomplished and the femoral component has been fixed. In spite of our results that the mean posterior slope of the medial tibia plateaus was 12.03°with reference to the proximal tibia anatomical axis, because over posterior slope can induce more stress to the posterior part of tibial insert, increase the tenseness of the extensor mechanism, and also the limitation of sampling error of our study, considering other’s studies described in the literature, we propose that the posterior tibial slope be maintained in 10°. Kinematic mode of normal knee between the femur and tibia is affected by multi of factors when moving from extension to flexion. Besides the configuration of distal femur and proximal tibia can affect the Kinematic mode of normal knee, other factors, as well as the mechanism that the movement between the femur and tibia guided by the variation of cruciate ligament tension during knee moving from extension to flexion, the mode of menisci movement to accommodate the movement between the femur and tibia, should be further studied.更多还原