全膝关节置换术后股胫关节运动学轨迹的数字化模型研究

 目的 通过透视技术结合数字化模型注册技术分析全膝关节置换术后股骨假体与胫骨垫片之间的相对运动和接触位置。方法 2007年7月至2008年6月,接受GENESISⅡ假体全膝关节置换术患者16例,均为女性;年龄56～76岁,平均66.4岁。随访48～60个月,平均(56±3)个月。采用膝关节学会评分(Knee Society Score,KSS)评价膝关节功能;采用循环透视方法获取影像学数据,对假体逆向数字建模,进行数字模型和影像学数据的匹配,重建膝关节的三维运动;测量股骨内、外髁接触位置的移动,计算胫骨内旋角度,测量股骨凸轮和胫骨立柱的接触时相和范围。结果 末次随访时KSS膝评分(93±5)分,功能评分(88±13)分,与术前比较差异有统计学意义。股骨内髁的移动范围(8.5±2.5) mm,外髁的移动范围(9.5±4.8) mm,胫骨内旋角度2.5°±8.4°。屈膝约30°～40°时凸轮和立柱发生接触,立柱后方的接触范围(8.0±1.8) mm。胫骨平台后倾角度越大,凸轮和立柱的接触越晚。结论 全膝关节置换术后股胫关节的运动学特征与正常膝关节不同,膝关节屈曲10°~30°时股骨内髁前移,屈曲大于40°后股骨内、外髁后移,胫骨平台后倾与凸轮和立柱的接触时相有相关性。     

Anterior tibial post impingement in a posterior stabilized total knee arthroplasty.

Despite the numerous long-term success reports of posterior stabilized (PS) total knee arthroplasty (TKA), recent retrieval studies of various PS TKA designs revealed wear and deformation on the anterior side of the tibial post. This study investigated the mechanisms of anterior impingement of the post with the femoral component. Seven cadaveric knees were tested to study kinematics and tibial post biomechanics during simulated heel strike using an in vitro robotic testing system. Intact knee kinematics and in situ anterior cruciate ligament (ACL) forces were determined at hyperextension (0 degree to -9 degrees) and low flexion angles (0 degrees to 30 degrees) under the applied loads. The same knee was reconstructed using a PS TKA. The kinematics and the tibial post contact forces of the TKA were measured under the same loading condition. The ACL in the intact knee carried load and contributed to knee stability at low flexion angles and hyperextension. After TKA, substantial in situ contact forces (252.4 +/- 173 N at 9 degrees of hyperextension) occurred in the tibial post, indicating anterior impingement with the femoral component. Consequently, the TKA showed less posterior femoral translation compared to the intact knee after the impingement. At 9 degrees of hyperextension, the medial condyle of the intact knee translated 0.1 +/- 1.1 mm whereas the medial condyle of the TKA knee translated 5.6 +/- 6.9 mm anteriorly. The lateral condyle of the intact knee translated 1.5 +/- 1.0 mm anteriorly whereas the lateral condyle of the TKA knee translated 2.1 +/- 5.8 mm anteriorly. The data demonstrated that anterior tibial post impingement functions as a substitute for the ACL during hyperextension, contributing to anterior stability. However, anterior post impingement may result in additional polyethylene wear and tibial post failure. Transmitted impingement forces might cause backside wear and component loosening. Understanding the advantages and disadvantages of the tibial post function at low flexion angles may help to further improve component design and surgical techniques and thus enhance knee stability and component longevity after TKA.     

Il posizionamento rotatorio della componente tibiale nella protesi totale di ginocchio

Correct rotational alignment of the femoral and tibial components is an important factor for successful TKA. The transepicondylar axis is widely accepted as a reference for the femoral component, but there is not a standard reference for the tibial component. Internally rotated components compromise knee biomechanics causing patellar maltracking, a tight medial flexion gap, and limited femoral rollback on a conforming lateral tibial condyle. In this article we show our “curve on curve” matching method to avoid tibial malrotation in primary TKA.     

Effect of femoral and tibial component position on patellar tracking following total knee arthroplasty: 10-year follow-up of Miller-Galante I knees

Rotational alignment of the femoral and tibial components using computed tomography (CT) was evaluated to establish if errors of alignment have a significant effect on patellofemoral complications. From 1987-1990, 54 knees in 39 patients were replaced with the Miller-Galante I knee system. Of these, 10 patients (13 knees) comprised this study. All patients had osteoarthritis. Mean patient age at surgery was 70.3 years. Mean follow-up was 10.3 years. On CT, rotational position of the femoral component relative to the epicondylar axis and the position of the tibial component relative to the tibial tubercle were evaluated. Patellar displacement and patellar tilt angle also were evaluated when the knee was flexed at 30 degrees. Mean rotation of the femoral component was 6.1 degrees of internal rotation (2.7 degrees-11.2 degrees). Mean rotation of the tibial component was 16.7 degrees of internal rotation (2.4 degrees-27.7 degrees). Mean lateral patellar tilt angle was 2.9 degrees (-6.0 degrees-11.9 degrees), and mean lateral displacement was 2.7 mm (-3.2-8.9 mm). Rotational position of both the femoral and tibial components showed a statistically significant correlation with the patellar tilt angle. This study showed the internally rotated femoral and tibial component were related to the patellar maltracking. This malalignment of the components, as well as nonanatomical patellar groove and metal-backed patellar component, could be one of the causes of the patellofemoral complications with the Miller-Galante I knee.     

综合手术治疗膝关节骨性关节炎合并膝内翻

目的 为使膝关节骨性关节炎合并膝内翻的年轻患者延缓行全膝关节置换,探讨股骨内髁马赛克植骨、髌骨成形并胫骨高位截骨综合手术治疗膝关节骨性关节炎合并膝内翻的临床疗效.方法 2004年6月-2006 年2月,对8例10膝骨性关节炎合并膝内翻患者行综合手术治疗.其中男2例3膝,女6例7膝;年龄42～56岁.左膝3例,右膝3例,双膝2例.患者均表现为行走或站久后疼痛.X 线片示股胫关节及髌骨边缘骨质增生,以内侧为重,髌股关节间隙变窄或消失,膝关节内侧间隙明显变窄.股胫角185～200°,平均 190°;HSS 膝关节评分为55～75分,平均60分.膝痛1～12年,平均5年. 结果 术后切口均Ⅰ期愈合,无早期并发症发生.患者均获随访7～24个月,平均15个月.患者截骨部位均于8～11 周达临床愈合,平均9周.股胫角矫正15～30°,平均 20°,基本恢复正常负重力线,膝关节外翻角 10°.术后关节活动度为 100～120°,较术前增加 5～20°,平均增加 10°.X 线片示膝关节内翻畸形基本纠正,截骨处无移位,内固定无松动、断裂.术后6个月HSS膝关节评分75～88分,平均80分. 结论 股骨内髁马赛克植骨使关节软骨得到一定程度的修复重建,髌骨成形有效解决膝前区疼痛,胫骨高位截骨矫正异常负重力线,三者结合,疗效肯定.     

髌骨形态异常与膝关节骨关节炎之间相关性

目的利用计算机辅助测量技术,对一定样本量的甘肃省中医院影像科膝关节X线片进行骨形态测量和相关比值分析研究,得出膝关节相关参数的正常范围,确立膝关节发育缺陷与膝关节骨关节炎之间相关性,找出导致髌股关节骨关节炎的骨性致病因素。方法测量指标:股骨髁宽度、胫骨髁宽度、髌骨宽度、髌骨纵径、髌骨关节面高度、髌骨厚度、髌骨下缘与关节间隙距离、股骨内髁前后径、胫骨平台前后径、髌骨关节面距胫骨平台距离、髌骨中点距股骨纵轴距离,采用SPSS 17.0软件对各有关比值进行处理和分析,采用90%(p5~p95)医学参考范围为正常参考范围描述;计数资料采用χ2检验,设检验水平为0.05,P0.05为差异有显著性意义。结果通过测量136例正常膝关节X线片各骨形态数据及相关比值,以90%医学参考范围为正常范围,得出髌骨厚度/股骨内髁前后径:0.162 362~0.335 135,髌骨纵径/髌骨关节面高度:1.217 105~1.643 902为正常范围。以此标准在481例膝关节骨关节炎病例中,髌骨厚度/股骨内髁前后径异常率6.4%,髌骨纵径/髌骨关节面高度异常率23.5%。结论髌骨偏厚、髌骨偏薄等形态异常在膝骨关节炎中占有一定的比例且女性发病率高于男性。     

Patellar tracking and patellofemoral geometry in deep knee flexion.

Patellar tracking and femoral condylar geometry in deep knee flexion were evaluated using magnetic resonance imaging. The patellar tilting angle, patellar shift, and patellar anteroposterior translation from 0 degrees to 135 degrees flexion were measured. The depth of the femoral condylar articular surface and the curvature of the femoral condylar articular surface also were measured at 135 degrees flexion. The patella shifted laterally, tilted medially, and sank deeply into the intercondylar notch during deep knee flexion. The articular surface of the lateral condyle, existing deep within the intercondylar notch, began to curve steeply at a point farther from the center of the intercondylar notch than did the medial condyle. The geometry of the femoral condyle is adequate to fit the patellar geometry. Results of the current study suggest that the geometry of the lateral femoral condyle allows the patella to track smoothly with a larger patellofemoral contact area and less patellofemoral pressure during deep flexion.     

Influence of intra-operative parameters on postoperative early recovery of active knee flexion in posterior-stabilized total knee arthroplasty

Purpose

Active knee flexion is more important for daily activities than passive knee flexion. The hypothesis is that the intra-operative parameters such as osteotomized bone thickness and soft tissue balance affect the postoperative active flexion angle in total knee arthroplasty (TKA). Therefore, we evaluate the influence of intra-operative parameters on postoperative early recovery of active flexion after posterior-stabilized (PS) TKA.

Methods

The subjects were 45 osteoarthritic knees undergoing primary PS TKA with anterior-reference technique. Intra-operative soft tissue balance was measured using an offset type tensor, and each osteotomized bone thickness was also measured. Pre- and postoperative active knee flexion angles were measured using lateral radiographs. Liner regression analysis was used to determine the influence of these intra-operative parameters on postoperative active flexion angles or recovery of active flexion angles.

Results

Pre-operative flexion angle was positively correlated with postoperative flexion angle (R?=?0.52, P?=?0.0002). Postoperative flexion angle was negatively correlated with the osteotomized bone thickness of femoral medial posterior condyle (R?=??0.37, P?=?0.012), and femoral lateral posterior condyle (R?=??0.36, P?=?0.015). Recovery of flexion angle was slightly negatively correlated with gap difference calculated by subtracting joint gap at extension from that at flexion between osteotomized surfaces (R?=??0.30, P?=?0.046).

Conclusions

The osteotomized bone thickness of the femoral posterior condyle is a significant independent factor of postoperative flexion angles. This indicates that the restoration of the posterior condyle offset may lead to larger postoperative active flexion angles in PS TKA.     

固定平台后稳定型假体全膝关节置换术后的运动学研究

 目的 探讨固定平台后稳定型假体全膝关节置换(total knee arthroplasty,TKA)术后膝关节在负重屈膝下蹲时的运动学特征。方法 选取10名健康志愿者和10例固定平台后稳定型假体TKA术后患者。制作骨骼及膝关节假体三维模型,在持续X线透视下完成负重下蹲动作,膝关节屈曲度每增加15°截取一幅图像。通过荧光透视分析技术完成三维模型与二维图像的匹配,再现股骨与胫骨在屈膝过程中的空间位置,通过连续的图像分析比较正常与固定平台后稳定型假体TKA术后膝关节在负重下蹲时股骨内、外髁前后移动及胫骨内外旋转幅度。结果 负重下蹲时,正常膝关节平均屈曲136°,股骨内、外髁分别后移(7.3±1.2) mm和(19.3±3.1) mm,胫骨平均内旋23.8°±3.4°;TKA术后膝关节平均屈曲125°,股骨内、外髁分别后移(1.4±1.6) mm和(6.4±1.7) mm,胫骨平均内旋8.5°±3.4°。结论 固定平台后稳定型假体TKA术后膝关节运动与正常膝关节相似,均表现出股骨内、外髁后移及胫骨内旋运动,但幅度小于正常膝关节,且在屈膝过程中存在股骨矛盾性前移及胫骨外旋现象。     

Akagi胫骨前后轴在全膝关节置换术中的定位作用

目的 分析膝关节CT片上Akagi胫骨前后轴与髌腱中内1/3点、髌腱内侧缘等解剖标志的相互关系,确定全膝关节置换术中胫骨假体旋转定位的参照轴线.方法 对40名青年健康志愿者行膝关节伸直中立位CT检查.Akagi胫骨前后轴定义为CT片上垂直于外科经上髁轴且经过后十字韧带中点的直线.于胫骨平台平而及预定截骨平面标记胫骨前后轴及其与髌腱相交点、后十字韧带中点与髌腱内侧缘及髌腱中内1/3点连线,分别测量胫骨前后轴与髌腱相交点内侧髌腱占髌腱总宽度的比例、后十字韧带中点与髌腱内侧缘及髌腱中内1/3点连线同胫骨前后轴之间的夹角.结果 在胫骨平台平面,胫骨前后轴经过髌腱内侧缘外侧10.1%±8.3%处;在预定截骨平面,胫骨前后轴经过髌腱内侧缘外侧0.2%±10.0%处.在预定截骨平面,后十字韧带中点与髌腱内侧缘连线和胫骨前后轴的夹角为0.1°±2.7°,后十字韧带中点与髌腱中内1/3点连线和胫骨前后轴的夹角为10.3°±3.6°.结论 全膝关节置换术中,当以胫骨结节中内1/3点为标准行胫骨假体旋转放置时,有导致胫骨假体相对于股骨假体过度外旋的可能.后十字韧带中点与髌腱内侧缘连线几乎与Akagi胫骨前后轴重叠,可以作为全膝关节置换术中胫骨假体旋转定位的参照轴线.     

复合软组织手术对儿童习惯性髌骨脱位髌股关节适应性的影响

目的 研究复合软组织手术治疗不同年龄段儿童习惯性髌骨脱位后,髌股关节适应性的变化情况.方法 回顾性分析2000至2007年收治的习惯性髌骨脱位患儿73例.男24例,女49例;平均年龄7.1岁(3～15岁);单侧47例,双侧26例.按照年龄分为A、B两组:A组年龄3～8岁(包括8岁),24例(30膝);B组年龄8～15岁,49例(69膝).复合软组织手术包括膝关节外侧充分松解、内侧紧缩、髌腱半腱上点移位(Roux-Goldthwait手术)和股内侧肌止点下移术.术前及随访中分别行髌骨轴位和侧位X线检查,测量股骨滑车角、髌骨高度、髌骨-滑车适配角及髌骨倾斜角(Laurin角)的变化情况,以评价髌股关节适应性.结果 73例患儿均获随访,平均随访38个月(25～98个月).末次随访时髌骨脱位均无复发,其中2例发生髌骨内侧脱位.股骨滑车角:A组由术前的150.1°±5.1°改善为144.3°±6.0°,手术前后差异有统计学意义(P＜0.05);B组手术前后差异无统计学意义(P＞0.05).其余测量指标在两组均无显著变化.结论 复合软组织手术对儿童习惯性髌骨脱位髌股关节的塑型有影响,对于手术年龄在8岁以下儿童可以明显促进股骨髁的发育,降低股骨滑车角,改善髌股关节适应性;8岁以上儿童在随访期内股骨滑车角的变化不显著,髌股关节适应性改变不明显.     

Patellofemoral resurfacing at total knee arthroplasty

A retrospective review of 268 primary total knee arthroplasties (TKAs) with a mean follow-up of four years is presented. The patellae were resurfaced in all cases. There were six complications (2.2%) referable to the patellofemoral articulation: three subluxations, one patellar fracture, one loosening of a metal-backed patellar component, and one patellar tendon avulsion. Successful patellofemoral resurfacing (PFR) can be accomplished with minimal complications if the following technical considerations are met: 5-7 degrees of valgus alignment; medial placement of the patellar component; taking care not to increase either the AP diameter of the knee or the thickness of the patella; avoiding internal rotation of either the tibial or femoral components and proper soft tissue balancing. A thorough review of patellofemoral complications after TKA is presented, and technical considerations relevant to the successful performance of PFR are discussed.     

Axial computed tomography of the patellofemoral joint with and without quadriceps contraction

Computed tomography was used to analyze the patellofemoral relationship during the first 60° of knee flexion in patients with chronic patellofemoral pain syndrome (49 knees) and a healthy control group (15 knees). The patellofemoral joints were imaged axially through the center of the patella articular cartilage with the knee flexed 0°, 0° with maximal quadriceps muscle contraction, 30°, and 60°. In 0° of knee flexion, the sulcus angle was greater in the symptomatic group than in normal controls. The patella displaced further laterally, and the lateral patellar tilt was greater. The patellar lateral index was found to be greater at 0° and indicated severe abnormality with full quadriceps muscle contraction. The Laurin angle was pathologic with increased medial opening, especially with muscle contraction. At 30° of knee flexion, these differences were less marked than at 0°. No relevant differences were found with 60° of knee flexion. This study showed that the sulcus angle, lateral patellar displacement, lateral patellar tilt, patella lateral condyle index, and Laurin angle are relevant diagnostic features in 0° of knee flexion, indicating a pathological femoral patellar gliding mechanism. Our evaluation also demonstrated the influence of full quadriceps muscle contraction, especially regarding lateral patellar displacement and the Laurin angle, and it was most prominent on the patella lateral condyle index. Thus, quadriceps muscle contraction often creates a more pathological displacement of the patella, which can be depicted using axial computed tomography.     

Tibial axis and patellar position relative to the femoral epicondylar axis during squatting

A laboratory-based study was performed to describe the tibial axis and patellar position relative to the femoral epicondylar (FE) axis during squatting. During the squat, the angle between the tibial and FE axes averaged 90.5 degrees, and 66% of internal rotation of the tibia occurred before 15 degrees flexion. In the mid-sagittal plane of the femur, the patella followed a circular arc, and mediolateral patellar shift averaged 4.3 mm. These findings can be used as the basis for development of new total knee arthroplasty components that recreate normal patellofemoral kinematics, and may provide important guidelines for alignment of the tibial and femoral components. The perpendicular relationship between the tibial and the FE axes may be useful in locating the FE axis intraoperatively. The reduced mediolateral shift of the patella suggests that alignment of the femoral component with the FE axis will aid patellar tracking about a circular arc with small deviations in the medial-lateral direction.     

In vivo three-dimensional knee kinematics using a biplanar image-matching technique.

A biplanar image-matching technique was developed and applied to a study of normal knee kinematics in vivo under weightbearing conditions. Three-dimensional knee models of six volunteers were constructed using computed tomography. Projection images of the models were fitted onto anteroposterior and lateral radiographs of the knees at hyperextension and every 15 degrees from 0 degrees to 120 degrees flexion. Knee motion was reconstructed on the computer. The femur showed a medial pivoting motion relative to the tibia during knee flexion, and the average range of external rotation associated with flexion was 29.1 degrees . The center of the medial femoral condyle translated 3.8 mm anteriorly, whereas the center of the lateral femoral condyle translated 17.8 mm posteriorly. This rotational motion, with a medially offset center, could be interpreted as a screw home motion of the knee around the tibial knee axis and a posterior femoral rollback in the sagittal plane. However, the motion of the contact point differed from that of the center of the femoral condyle when the knee flexion angle was less than 30 degrees. Within this range, medial and lateral contact points translated posteriorly, and a posterior femoral rollback occurred. This biplanar image-matching technique is useful for investigating knee kinematics in vivo.     

影响骨关节炎患者全膝关节置换术后关节功能的相关因素分析

[目的]探讨影响骨关节炎患者全膝关节置换术后关节功能的相关因素.[方法]对41例43膝骨关节炎终末期行全膝关节置换术(total knee arthroplasty,TKA)患者术前、术后半年的膝关节功能进行HSS评分,应用Pearson相关分析及多重线性回归对术后膝关节HSS评分与患者年龄、体重指数、疼痛评分、术前膝关节活动度(ROM)、内翻畸形程度、手术前后股骨前髁偏距(ACO)变化情况,术后胫骨平台后倾角(PSA)等因素进行统计分析;并分析手术前后股骨前髁偏距(ACO)变化情况,术后胫骨平台后倾角(PSA)与术后膝关节ROM之间的关系.[结果]Pearson相关分析结果可以看出术前疼痛评分、术前膝关节ROM、术后胫骨平台PSA、手术前后股骨ACO变化与术后膝关节功能HSS评分呈正相关;体重指数、膝内翻畸形程度与术后膝关节功能HSS评分呈负相关.逐步回归分析经筛选后纳入方程的变量只有术后胫骨平台PSA (P＜0.01)、术前疼痛功能评分(P＜0.01)、体重指数(P＜0.05),根据标准回归系数的绝对值大小排序,对应变量的作用排序为术后胫骨平台PSA (0.555)＞术前疼痛评分(0.357)＞体重指数(0.187).ACO术前大于术后组的患者术后膝关节ROM明显好于ACO术前小于术后组(P＜0.05).术后胫骨平台PSA 7°～9°组术后膝关节活动度最好.[结论](1)术前疼痛评分、术前膝关节ROM、术后胫骨平台PSA、术前术后股骨ACO变化与术后膝关节HSS评分呈正相关,体重指数、膝关节内翻畸形与术后膝关节功能HSS评分呈负相关;(2)术后胫骨平台PSA、术前疼痛评分、体重指数对术后半年膝关节HSS评分影响显著;(3)股骨ACO变化对术后膝关节活动度有影响,术后胫骨平台PSA7°～9°膝关节活动度好.     

膝关节软骨人体标本解剖与磁共振成像的比较研究

目的 探讨膝关节尸体标本解剖与磁共振成像(MRI)三维序列-扰相梯度回波序列(3D-FS-SPGR)测量关节软骨厚度的差异,并分析软骨组织主要成分在关节软骨不同位置的差异.方法选用国人青壮年中等身材、无明显关节病变的成年男性尸体膝关节标本2具,首先进行3D-FS-SPGR序列矢状位扫描.复冻后按解剖部位进行矢状位解剖,分别对股骨及胫骨内、外髁负重区前、后面及髌骨面软骨厚度进行测量.关节软骨石蜡切片进行维多利亚蓝-丽春红复合染色并观察.结果 软骨尸体标本解剖与3D-FS-SPGR序列测得的膝关节软骨厚度:股骨外侧髁前负重面平均分别为2.25、2.25 mm,股骨外侧髁后负重面平均分别为2.70、2.75 mm,胫骨外侧髁前负重面平均分别为2.00、2.10 mm;胫骨外侧髁后负重而平均分别为2.35、2.25 mm,股骨内侧髁前负重面平均分别为2.20、2.20 mm,股骨内侧髁后负重面平均分别为2.15、2.30 mm,胫骨内侧髁前负重面半均分别为2.20、2.45mm,胫骨内侧髁后负重面平均分别为2.70、2.95 mm,髌骨面软骨平均分别为3.08、3.15 mm.软骨组织学染色显示:关节软骨表层胶原纤维含量相对较多,软骨细胞及其周围基质相对较少;在关节软骨深层,胶原纤维含量相对较少,而软骨及软骨周围基质相对较多.结论 3D-FS-SPGR序列能够相对真实地反映关节软骨的形态及厚度.胶原纤维主要集中在软骨表层,其分布与软骨的功能相一致.

Abstract：

Objective To compare corpse sampling and MR imaging with 3D-FS-SPGR sequences in measurement of the articular cartilage thickness and to investigate knee cartilage topography. Methods Two fresh specimens of the knee joint were obtained from 2 normal young adult male corpses of medium stature. MR1 scanning was carried on the 2 specimens in sagittal 3D-FS-SPGR MR sequences. After defrosted,the knee specimens were dissected longitudinally, and the cartilage thicknesses were measured at different locations of the knee joint. Paraffin sections of the knee cartilage were observed following compound staining with victoria blue and ponceau red. Results The average cartilage thicknesses measured by dissection and MR imaging sequence were respectively: 2. 25 mm and 2. 25 mm at the anterior weight-loading surface of the femoral lateral condyle, 2. 70 mm and 2. 75 mm at the posterior weight-loading surface of the femoral lateral condyle, 2. 00 mm and 2. 10 mm at the anterior weight-loading surface of the tibial lateral condyle,2. 35 mm and 2. 25 mm at the posterior weight-loading surface of the tibial lateral condyle, 2. 20 mm and 2. 20mm at the anterior weight-loading surface of the femoral medial condyle, 2. 15 mm and 2. 30 mm al the posterior weight-loading surface of the femoral medial condyle, 2. 20 mm and 2.45 mm at the anterior weight-loading surface of the tibial medial condyle, 2. 70 mm and 2. 95 mm at the posterior weight-loading surface of the tibial medial condyle and 3. 08 mm and 3. 15 mm at patella cartilage surface. Collagen fibers were rich at the periphery of the articular cartilage with sparse chondrocytes and matrixes, while the opposite was observed at the center of the articular cartilage. Conclusions MR imaging with 3D-FS-SPGR sequences can display the actual knee cartilage topography. Collagen fibers mainly concentrate at the periphery of the articular cartilage, which accounts for the function of the articular cartilage.     

Hybrid total knee arthroplasty

A prospective study of a hybrid total knee arthroplasty (TKA) with an uncemented femoral component and cemented tibial and patellar components was performed to combine the advantage of a press-fit femur while avoiding the problems in uncemented tibial and patellar implants. A total of 329 posterior cruciate-preserving TKA were studied at an average of 4.7 years after surgery: 84% of the knees had at most mild or occasional pain, 68% had good or excellent knee scores, and 62% could walk more than 1000 m. The function scores were 40% good or excellent in this collective, with an average age of 69.4 years at surgery. The component position and alignment were biomechanically correct. Radiolucent lines were observed regularly at the edges of the tibial and femoral components. There were no revisions for aseptic loosening. Hybrid TKA provides good results comparable to cemented TKA.     

膝关节软骨人体标本解剖与磁共振成像的比较研究

目的 探讨膝关节尸体标本解剖与磁共振成像(MRI)三维序列-扰相梯度回波序列(3D-FS-SPGR)测量关节软骨厚度的差异,并分析软骨组织主要成分在关节软骨不同位置的差异.方法选用国人青壮年中等身材、无明显关节病变的成年男性尸体膝关节标本2具,首先进行3D-FS-SPGR序列矢状位扫描.复冻后按解剖部位进行矢状位解剖,分别对股骨及胫骨内、外髁负重区前、后面及髌骨面软骨厚度进行测量.关节软骨石蜡切片进行维多利亚蓝-丽春红复合染色并观察.结果 软骨尸体标本解剖与3D-FS-SPGR序列测得的膝关节软骨厚度:股骨外侧髁前负重面平均分别为2.25、2.25 mm,股骨外侧髁后负重面平均分别为2.70、2.75 mm,胫骨外侧髁前负重面平均分别为2.00、2.10 mm;胫骨外侧髁后负重而平均分别为2.35、2.25 mm,股骨内侧髁前负重面平均分别为2.20、2.20 mm,股骨内侧髁后负重面平均分别为2.15、2.30 mm,胫骨内侧髁前负重面半均分别为2.20、2.45mm,胫骨内侧髁后负重面平均分别为2.70、2.95 mm,髌骨面软骨平均分别为3.08、3.15 mm.软骨组织学染色显示:关节软骨表层胶原纤维含量相对较多,软骨细胞及其周围基质相对较少;在关节软骨深层,胶原纤维含量相对较少,而软骨及软骨周围基质相对较多.结论 3D-FS-SPGR序列能够相对真实地反映关节软骨的形态及厚度.胶原纤维主要集中在软骨表层,其分布与软骨的功能相一致.     

In Vivo Knee Kinematics for a Cruciate Sacrificing Total Knee Arthroplasty Having Both a Symmetrical Femoral and Tibial Component

BackgroundEarly total knee arthroplasty (TKA) designs were symmetrical, but lead to complications due to over-constraint leading to loosening and poor flexion. Next-generation TKAs have been designed to include asymmetry, pertaining to the trochlear groove, femoral condylar shapes, and/or the tibial component. More recently, an advanced posterior cruciate sacrificing (PCS) TKA was designed to include both a symmetrical femoral component with a patented V-shaped trochlear groove and a symmetrical tibial component with an ultracongruent insert, in an attempt to reduce inventory costs. Because previous PCS TKA designs produced variable results, the objective of this study is to determine and evaluate the in vivo kinematics for subjects implanted with this symmetrical TKA.MethodsTwenty-one subjects, implanted with symmetrical PCS fixed-bearing TKA, were asked to perform a weight-bearing deep knee bend (DKB) while under fluoroscopic surveillance. A 3-dimensional to 2-dimensional registration technique was used to determine each subject’s anteroposterior translation of lateral and medial femoral condyles as well as tibiofemoral axial rotation and their weight-bearing knee flexion.ResultsDuring the DKB, the average active maximum weight-bearing flexion was 111.7° ± 13.3°. On average, from full extension to maximum knee flexion, subjects experienced −2.5 ± 2.0 mm of posterior femoral rollback of the lateral condyle and 2.5 ± 2.2 mm of medial condyle motion in the anterior direction. This medial condyle motion was consistent for the majority of the subjects, with the lateral condyle exhibiting rollback from 0° to 60° of flexion and then experienced an average anterior motion of 0.3 mm from 60° to 90° of knee flexion. On average, the subjects in this study experienced 6.6°± 3.3° of axial rotation, with most of the rotation occurring in early flexion, averaging 4.9°.ConclusionAlthough subjects in this study were implanted with a symmetrical PCS TKA, they did experience femoral rollback of the lateral condyle and a normal-like pattern of axial rotation, although less in magnitude than the normal knee. The normal axial rotation pattern occurred because the lateral condyle rolled in the posterior direction, while the medial condyle moved in the anterior direction. Interestingly, the magnitude of posterior femoral rollback and axial rotation for subjects in this study was similar in magnitude reported in previous studies pertaining to asymmetrical TKA designs. It is proposed that more patients be analyzed having this TKA implanted by other surgeons.