人体膝关节股骨后髁角度的MRI测量

背景：全膝关节置换过程中股骨假体旋转力线良好非常重要,研究显示后髁角度是确定力线的重要依据,后髁角度为股骨后髁轴与股骨手术髁上轴之间角度,MRI测量可清晰显示后髁软骨、外上髁突起及内上髁凹陷,从而保证测量数据的准确。目的：测量保定北部地区人群中膝关节后髁角度,为临床实施全膝关节置换过程中确定股骨假体旋转力线提供影像学依据。方法：应用核磁共振机对入选中青年人群膝关节进行扫描,取膝关节伸直中立位,扫描平面垂直于膝关节机械轴,选择T1像上最佳膝关节轴位平面,由两名观察者独自分析图像,通过Bravo viewer 6.0影像软件观察股骨内上髁存在率,画出股骨髁上轴线及后髁线并测量两条轴线之间角度,即股骨后髁角度。结果与结论：入选人群男性股骨后髁角度为（2.73±1.28）°,女性股骨后髁角度为（2.35±1.37）°,不同性别间差异无显著性意义。提示MRI测量股骨后髁角具有较大优越性,人工全膝关节置换过程中髁上轴线变异性较小,可参照后髁角度定位安装股骨假体,避免膝关节置换后并发症发生。     

三维骨建模系统在人工全膝关节置换旋转对位中的作

背景:前期人工全膝关节置换试验证实,采用以三维骨建模为基础的计算机辅助系统可以进行精确地假体三维定位及下肢力线重建,减少髌股关节并发症,取得韧带平衡,获得良好的临床效果.目的:拟进行人工全膝关节置换时假体旋转对位的量化分析,验证三维骨建模的计算机辅助手术系统对量化操作的精确性和有效性.设计、时间及地点:回顾性病例分析,于2002-11/2003-06在法国亨利蒙多医院矫形与创伤外科完成.对象:纳入保守治疗无效的三间隔骨性关节炎患者21例(21膝),其中14例膝内翻,7例膝外翻;患者均为初次置换,所用假体为后稳定型人工表面全膝关节(Hermes(R),Ceraver,法国).方法:采用三维骨建模Ceravision系统对21例患者(21膝)进行人工全膝关节置换.计算机系统提供假体预设方案,安置好截骨定位导向装置后进行截骨,注意保持良好的伸屈膝关节间隙和韧带平衡及关节稳定,额面上控制应力下膝内外翻在±3°以内,下肢力线(180±3)°以内,适当地假体旋转对位后行假体固定.主要观察指标:根据相关的临床体检、影像学和导航系统资料,对术中假体旋转对位测量值、置换后3个月膝关节活动度、膝关节松弛度和髌骨稳定性进行观察分析.结果:在保证下肢力线与膝关节额面松弛度于正常范围内,术中股骨假体旋转对位内旋1°～外旋5°,胫骨假体旋转对位内旋0°～外旋5°.其中14例膝内翻患者,股骨假体旋转对位内旋1°～外旋5°,胫骨假体旋转对位内旋2°～外旋5°;7例膝外翻患者,股骨假体旋转对位内旋1°～外旋4°,胫骨假体旋转对位内旋0°～外旋 4°.置换后3个月时,膝关节最大屈膝度为105°～130°,平均115°,无膝痛、髌骨失稳和脱位等并发症,膝关节额面松弛度无异常.结论:应用以三维骨建模为基础的人工全膝关节置换计算机辅助手术系统,可针对患者个体精确三维截骨和假体旋转对位,获得良好的膝关节屈伸位下关节等距间隙,保证良好的膝关节韧带张力与平衡稳定, 避免髌-股并发症,可在手术中常规使用.     

全膝关节置换过程中的假体旋转对位

背景：在全膝关节置换过程中对假体旋转对位争论的焦点目前仍集中在旋转对位的参照地标如何设定。目的：综述全膝关节置换手术中假体旋转对位的相关临床和基础研究进展。方法：广泛查阅全膝关节置换手术中假体旋转对位的解剖定位标志、定位方法、旋转对位的匹配、手术精确度等临床上遇到的相关文献。结果与结论：许多研究表明,旋转对位不良,会导致膝前痛,胫股骨和髌股关节间的稳定性失衡,髌骨的运动轨迹失调,步态异常,胫骨侧聚乙烯平台的磨损加速,假体过早松动,出现关节半脱位和脱位,甚至需进一步手术翻修等问题。术中胫股骨侧假体的旋转对位时要综合利用所获得的各种信息,个别校正,必要时结合置换前的CT扫描来进行,以改善全膝关节置换疗效和远期生存率。     

全膝关节置换过程中的假体旋转对位

背景:在全膝关节置换过程中对假体旋转对位争论的焦点目前仍集中在旋转对位的参照地标如何设定。目的:综述全膝关节置换手术中假体旋转对位的相关临床和基础研究进展。方法:广泛查阅全膝关节置换手术中假体旋转对位的解剖定位标志、定位方法、旋转对位的匹配、手术精确度等临床上遇到的相关文献。结果与结论:许多研究表明,旋转对位不良,会导致膝前痛,胫股骨和髌股关节间的稳定性失衡,髌骨的运动轨迹失调,步态异常,胫骨侧聚乙烯平台的磨损加速,假体过早松动,出现关节半脱位和脱位,甚至需进一步手术翻修等问题。术中胫股骨侧假体的旋转对位时要综合利用所获得的各种信息,个别校正,必要时结合置换前的CT扫描来进行,以改善全膝关节置换疗效和远期生存率。     

Medial tilting of the joint line in posterior stabilized total knee arthroplasty increases contact force and stress

BackgroundKinematically aligned total knee arthroplasty is based on the concept to represent the premorbid joint alignment with cruciate-retaining implants, characterized by medial tilt and internal rotation. However, kinematic and kinetic effects of kinematically aligned total knee arthroplasty with posterior-stabilized implants is unknown. The purpose of this study was to examine the effect of medial tilting of the joint line with posterior-stabilized implants.MethodsA mechanical alignment model, and medial tilt 3° and 5° models were constructed. Knee kinematics and contact forces were simulated using a musculoskeletal computer simulation model. Contact stresses on the tibiofemoral joint and the post area were then calculated using finite element analysis.FindingsFrom 0° to 120° of knee flexion, greater external rotation of the femoral component was observed in medial tilt models (−0.6°, 1.8° and 4.2° in mechanical alignment, medial tilt 3° and medial tilt 5° models, respectively). The peak contact stresses on the tibiofemoral joint and the post area at 120° of knee flexion were higher in medial tilt models. The peak contact stresses on the post area in medial tilt 3° and 5° models were 2.2 and 3.8 times greater than that in mechanical alignment model, respectively.InterpretationMedial tilting of the joint line causes greater axial rotation even with posterior-stabilized implants, which can represent near-normal kinematics. However, medial tilting of the joint line in total knee arthroplasty with posterior-stabilized implants may have a higher risk for polyethylene wear at the tibiofemoral joint and post area, leading to subsequent component loosening.     

Impact of intraoperative adjustment method for increased flexion gap on knee kinematics after posterior cruciate ligament-sacrificing total knee arthroplasty

BackgroundIn general, the flexion gap is larger than the extension gap with posterior cruciate ligament-sacrificing total knee arthroplasty. Several methods compensate for an excessive flexion gap, but their effects are unknown. The purpose of this study was to compare three methods to compensate for an increased flexion gap.MethodsIn this study, squatting in knees with excessive (4 mm) and moderate (2 mm) flexion gaps was simulated in a computer model. Differences in knee kinematics and kinetics with joint line elevation, setting the femoral component in flexion, and using a larger femoral component as compensatory methods were investigated.FindingsThe rotational kinematics during flexion with setting the femoral component in flexion were opposite to those in the other models. Using a larger femoral component resulted in the most physiological motion. The peak anterior translation was 10 mm in the joint line elevation model compared with approximately 6 mm in the other models. In the joint line elevation model, patellofemoral contact stress was excessively increased at 90° of knee flexion. In contrast, tibiofemoral contact stress was higher during knee extension with setting the femoral component in flexion due to anterior impingement. There were few differences in the effect of the three compensatory methods with a moderate flexion gap.InterpretationA larger femoral component should be used to compensate for an excessive flexion gap because it has less negative impact on posterior cruciate ligament-sacrificing total knee arthroplasty, whereas any compensation method might be acceptable for a moderate flexion gap.     

Extensor malalignment arising from femoral component malrotation in knee arthroplasty: Effect of rotating–bearing

Background

Many patellofemoral complications such as anterior knee pain, subluxation, fracture, wear, and aseptic loosening after total knee arthroplasty are attributed to malrotation of the femoral component. Rotating-platform mobile bearings can reduce malrotation between the tibial and femoral components and may also improve patellofemoral maltracking.

Methods

A computer model (LifeMOD/KneeSIM) of a weight-bearing deep knee bend was validated using cadaver knees tested in an Oxford-type knee rig. Changes in knee kinematics and patellofemoral forces were measured after femoral component malrotation of ± 3°. The effect of a rotating–bearing on these kinematics and forces was determined.

Findings

In a fixed-bearing arthroplasty femoral component internal malrotation increased tibiofemoral internal rotation by 3.4°, and external malrotation increased tibiofemoral external rotation by 4°. Femoral component malrotation affected patellofemoral lateral shift by up to 2.5 mm, and patellofemoral lateral shear by up to 19 N. When the malrotated femoral component was tested against a rotating–bearing the change in tibiofemoral rotation and patellofemoral lateral shift was less than 1° and 1 mm respectively. The rotating–bearing reduced peak lateral shear by 7 N and peak medial shear by 17 N. Increasing the conformity of the rotating–bearing reduced changes in tibiofemoral rotation due to femoral malrotation and increased the net rotation of the bearing (by approximately 5°) during flexion.

Interpretation

Our results are consistent with one randomized clinical outcome study and emphasize the value of computational modeling for preclinical design evaluation. It is important to continue to improve existing methodologies for accurate femoral component alignment especially in rotation.     

Biomechanical effects of joint line elevation in total knee arthroplasty

Background

Inadequate restoration of the knee joint line after total knee arthroplasty may lead to a poor clinical outcome. The purpose of this study was to quantitatively assess the effects of joint line elevation following total knee arthroplasty with increased joint volume on patellofemoral contact kinematics.

Methods

Six cadaveric specimens were tested. Patellofemoral contact area, contact pressure, and kinematics were measured following total knee arthroplasty with an anatomic joint line and after 4 and 8 mm of joint line elevation, at knee flexion angles of 0°, 30°, 60°, 90° and 120°. Repeated measures analysis of variance with a Tukey post hoc test with a significance level of 0.05 was used for statistical analyses.

Findings

There was a decrease in contact area with joint line elevation at flexion angles of 60°, 90° and 120° (P = 0.009–0.04). There was a significant increase in contact pressure only at 30° of knee flexion with 8 mm of joint line elevation (P = 0.004). Three of the six specimens showed inferior edge loading of the patella component following 8 mm of joint line elevation at 120° of knee flexion. The sagittal plane patellofemoral angle increased significantly with joint line elevation except for 0° knee flexion (P = 0.0002–0.02).

Interpretation

Knee joint line elevation with increased knee volume significantly affects patellofemoral contact area and kinematics and produced inferior edge loading/impingement between the patella and tibial components, this may result in loss of knee range of motion, postoperative pain, and premature component wear.     

安装假体时股骨旋转定位轴线及相关角度的解剖学特征

背景：人工全膝关节置换过程中股骨假体旋转定位良好是置换成功的关键之一，与置换后关节功能密切相关。股骨髁各项解剖参数也非常重要，熟悉其各项数据能够合理截骨以及选择轴线，避免假体安装位置不佳导致全膝关节置换后关节功能障碍。 目的：通过对股骨髁标本的解剖结构进行观察，测量股骨髁标本解剖参数及定位轴线之间的角度。 方法：固定架固定共40例股骨骨性标本，观察内上髁及外上髁形态变化，测量股骨髁解剖参数，包括长度、宽度等；应用定位导向器于内外上髁之间穿克氏针固定，垂直股骨后髁轴截骨后以万能角度量角器测量股骨4条轴线--手术髁上轴、临床髁上轴、后髁轴、AP轴之间的相关角度关系。 结果与结论：内上髁凹陷出现比例较低，约占所有标本比例总数的25%；股骨髁的高度与西方人相比差别不大，宽度与西方人相比差别较大。提示股骨髁宽度与西方人群差别较大，手术操作应充分注意；股骨髁内上髁凹陷出现比例不高，故参照髁上轴的后髁角定位只适用于部分人群；而 AP 轴较易定位，两条轴线与后髁轴线之间成角数值稳定，变异性较小，证实AP轴可做为股骨假体旋转定位的可靠标记。     

A computer model to simulate patellar biomechanics following total knee replacement: the effects of femoral component alignment

OBJECTIVE: The objective of this study is to analyze the biomechanics of the patellar component following total knee replacement. More specifically we investigated the effect of displacing the femoral component of an Insall-Burstein II total knee replacement on the patellar tracking and patello-femoral contact pressures. DESIGN: We used a validated computer simulation of the knee joint to virtually insert the femoral component with the following four types of placements: (1) no misplacement, (2) 5 degrees of internal rotation, (3) 5 degrees of external rotation and (4) 5 degrees of flexion rotation. The patellar 3D tracking and patello-femoral contact pressures were computed for each femoral component placement as a function of knee flexion angle. BACKGROUND: Complications at the patello-femoral joint are the among most frequent following total knee replacement. RESULTS: Femoral component placement unevenly affected the associated patellar tracking: a 5 degrees internal rotation tilted and rotated the patella laterally by about 5 degrees throughout knee flexion. A 5 degrees external rotation of the femoral component had less effect on patellar tracking. A rotation of 5 degrees in flexion primarily caused patellar rotation (5-10 degrees lateral rotation). Femoral component malalignment had only minor effects on the peak pressure distributions at the patello-femoral interface. CONCLUSION:These results suggest that femoral component positioning primarily affects patellar tracking, with a possible threat for patellar subluxation under external rotation of the femoral component. RELEVANCE: Precise alignment of the prosthetic components is difficult to control during total knee replacement due to the lack of precise anatomical landmarks in the human knee joint. Consequently, the position of each prosthetic component may differ from the ideal one suggested by the manufacturer. Improper alignment of the prosthetic components during total knee replacement may lead to premature implant failure.     

Varus alignment after total knee arthroplasty results in greater axial rotation during deep knee bend activity

BackgroundsThe correlation between in vivo knee kinematics and alignment has not been fully elucidated. Recently, similar or better clinical outcomes have been reported by restoration of mild varus alignment after total knee arthroplasty for preoperative varus knees. The aim of this study was to evaluate the effect of postoperative alignment on knee kinematics during a deep knee bend activity.MethodsIn vivo knee kinematics of 36 knees (25 patients) implanted with tri-condylar total knee arthroplasty were analyzed with a three dimensional model fitting approach using fluoroscopy. Under fluoroscopic surveillance, individual video frames were digitized at 30° increments from full extension to maximum flexion. Postoperative coronal and sagittal alignments were assessed using radiographs, and rotational alignment was assessed with computed tomography. Pearson correlation coefficients were calculated to determine the correlations between the alignment data and kinematic factors.FindingsCorrelation analysis showed that coronal alignment was significantly correlated with knee kinematics. The varus alignment of the limb and tibial component led to a greater axial rotation from full extension to maximum flexion and more rotated position in the mid to deep flexion range. Neither the rotational alignment of the femoral nor tibial components showed significant correlation with axial rotation from full extension to maximum flexion.InterpretationVarus alignment resulted in greater axial rotation, which could represent near-normal knee kinematics. The current study can be a kinematic rationale reporting similar or better clinical and functional outcomes for the total knee arthroplasty with residual varus alignment.     

Consistent femoral external rotation during weight-bearing knee flexion is associated with better patient-reported pain and mediolateral balance after total knee arthroplasty

BackgroundNormal knees generally show consistent femoral external rotation during knee flexion, although knees that have had total knee arthroplasty exhibit various rotational patterns with less rotational angle. This study aimed to determine whether consistent femoral external rotation during weight-bearing knee flexion after total knee arthroplasty is associated with better patient-reported outcomes and mediolateral joint balance.MethodsA total of 40 total knee arthroplasty knees with a high-flexion posterior-stabilized prosthesis were divided into two groups based on their axial rotational kinematic pattern during squatting activity, and the clinical results including patient-reported outcomes and joint laxity were compared between the consistent external rotation group (20 knees) and the inconsistent external rotation group (20 knees). The unpaired Student's t-test or Welch's test were used for group comparison, and Fisher's exact test was applied for categorical data.Findings“Pain at rest” and “Pain at first gait in the morning” measured using a numerical rating scale (/10) were significantly lower in the consistent external rotation group compared with those in the inconsistent external rotation group. “Pain during gait on flat surface” tended to be lower in the consistent external rotation group. Medial stability was obtained in both groups with significantly greater lateral laxity in extension in the inconsistent external rotation group.InterpretationTotal knee arthroplasty knees with consistent femoral external rotation during weight-bearing knee flexion exhibited better patient-reported pain and mediolateral soft tissue balance. Surgical procedures that control the mediolateral balance with medial stability would induce consistent femoral external rotation and improve patient-reported pain.     

Structural stability of a polyetheretherketone femoral component—A 3D finite element simulation

BackgroundBecause its mechanical properties are similar to cortical bones of the knee, polyetheretherketone (PEEK) material has been used to make total knee arthroplasty (TKA) components. This study investigated the PEEK femoral component deformation of a TKA system and compared the data with that of a cobalt–chromium (CoCr) component.MethodsA 3D finite element knee model was constructed using CT images of a normal subject. A knee prosthesis was installed on the model to simulate a TKA knee. The material properties of the bone were assumed linear and transverse isotropic. The femoral component was modeled using a PEEK or CoCr material. A compressive load was applied to the knee at full extension. Tibiofemoral contact stresses and femoral component deformations were analyzed.FindingsUnder a 3 kN load, the maximal Von-Mises stresses in the femoral component were 14.39 MPa and 30.05 MPa for the PEEK and CoCr components, respectively. At the tibial polyethylene surface, the CoCr femoral component caused higher contact stresses (>2.2%) than the PEEK component. The deformation of the PEEK component was over 3 times larger than that of the CoCr component (0.65 × 10⁻³ mm vs 0.2 × 10⁻³ mm).InterpretationThe PEEK femoral component could result in lower contact stresses, but larger deformations in the TKA knee compared to the CoCr component. An increased deformation of the PEEK component indicates a reduction in its structural strength. Future investigation should examine if the reduced structural strength will affect the in-vivo component-bone interface integration and affect the component fatigue life.     

The influence of contact alignment of the tibiofemoral joint of the prostheses in in vitro biomechanical testing

Objective. To investigate the influence of contact alignment of the tibiofemoral joint of the prostheses in in vitro biomechanical testing.

Design. An experimental set-up was used to measure the total contact areas of the tibiofemoral joint of the prostheses subjected to a compressive load, and the malalignment situations were simulated.

Background. The contact alignment of the femoral component related to the tibial component in the literature was not described clearly and the effect of malalignment on the testing method has not been reported well.

Methods. Three commercial knee prostheses (Omnifit, Genesis, and AMK) were used for testing under a compression load (3000 N) at flexion 0° and 10°. After aligning the normal contact alignment, the simulated malalignment was done to evaluate the influence on the total contact areas in these conditions relative to the normal contact alignment. The simulated malalignment includes the medial–lateral translation (0.5 and 1 mm), anterior–posterior translation (2 and 4 mm) and internal–external rotation (1°, 3° and 5°) of the femoral component relative to the tibial component.

Results. The ratios of total contact areas of malalignment relative to normal contact alignment ranged from 1.06 to 0.93 in medial–lateral malalignment in these three prostheses. In anterior–posterior malalignment, the ratios ranged from 0.69 to 0.79 in Omnifit, 0.93–0.96 in Genesis and 0.96–1.04 in AMK. In internal–external malrotation, the ratios ranged from 0.90 to 1.03 in these prostheses.

Conclusions. This study proposes that contact alignment would affect the contact characteristics, especially in anterior–posterior alignment when high conformity knee prosthesis is tested. The contact alignment must be standardized in the procedure in in vitro biomechanical testing, which will be more objective to evaluate the contact characteristics of different knee prostheses.

Relevance

This study revealed the importance of contact alignment of the tibiofemoral joint of the prosthesis in in vitro biomechanical testing. Many published reports of the biomechanical evaluations on different designs of knee prostheses would show different results due to contact alignment. Furthermore, this study indicates that the ideal contact characteristics of the tibiofemoral joint in original design will be changed when the prosthesis under the malalignment condition which was caused by surgery technique or soft tissues imbalance.     

Intra-operative joint gap kinematics in unicompartmental knee arthroplasty

Background

The use of an offset type tensor for total knee arthroplasty that can be set with patellofemoral joint reduction and femoral component placement enables surgeons to assess soft tissues in the physiological postoperative knee condition, showing different kinematic pattern of soft tissues in varus osteoarthritic knees between cruciate-retaining and posterior-stabilized total knee arthroplasty. However, gap kinematics in unicompartmental knee arthroplasty is unclear.

Methods

Using a newly developed tensor that is designed to assess soft tissue balance throughout the full range of motion with femoral component placement, we assessed the intra-operative joint gap measurements of unicompartmental knee arthroplasties performed at 0, 10, 30, 45, 60, 90, 120 and 135° of flexion in 20 osteoarthritic patients. In addition, the kinematic pattern of unicompartmental knee arthroplasty was compared with those of cruciate-retaining and posterior-stabilized total knee arthroplasty that were calculated as medial compartment gap from the previous series of this study.

Findings

While the joint gap measurements of unicompartmental knee arthroplasties increased from full extension to extension (10° of flexion), these values remained constant throughout the full range of motion. Of note, the gap values of cruciate-retaining total knee arthroplasty were significantly smaller from midrange to deep flexion compared with posterior-stabilized total knee arthroplasty, and furthermore unicompartmental knee arthroplasty showed a significantly smaller gap from extension to midrange flexion compared with cruciate-retaining total knee arthroplasty.

Interpretation

Accordingly, we conclude that the intra-operative joint gap kinematic pattern in unicompartmental knee arthroplasty differs from the pattern in total knee arthroplasty.     

Is latero-medial patellar mobility related to the range of motion of the knee joint after total knee arthroplasty?

Diminished range of motion (ROM) of the knee joint after total knee arthroplasty (TKA) is thought to be related to reduced patellar mobility. This has not been confirmed clinically due to a lack of quantitative methods adequate for measuring patellar mobility. We investigated the relationship between patellar mobility by a reported quantitative method and knee joint ROM after TKA. Forty-nine patients [osteoarthritis – OA: 29 knees; rheumatoid arthritis – RA: 20 knees] were examined after TKA. Respective medial and lateral patellar mobility was measured 1 and 6 months postoperatively using a patellofemoral arthrometer (PFA). Knee joint ROM was also measured in each of those 2 sessions. Although the flexion and extension of the knee joints improved significantly from 1 to 6 months after TKA, the medial and lateral patellar displacements (LPDs) failed to improve during that same period. Moreover, only the changes in knee flexion and medial patellar displacement (MPD) between the two sessions were positively correlated (r = 0.31, p < 0.05). However, our findings demonstrated that medial and lateral patellar mobility had no sufficient longitudinal relationship with knee ROM after TKA.     

Association between generalized joint laxity and knee joint movement in female university students

[Purpose] This study investigated the association between generalized joint laxity and knee joint movement in female university students. [Participants and Methods] The study included 21 female university students. Generalized joint laxity was measured using the Beighton criteria for joint hypermobility. Acceleration and angular velocities of the tibia during knee extension were measured along three axes using a triaxial accelerometer. Sampling data were expressed as root mean squares. The Mann–Whitney U test was used to determine differences in the acceleration and angular velocities along each axis between the generalized joint laxity and non-generalized joint laxity groups. Spearman’s rank correlations were used to confirm the association between these parameters. [Results] The rotational angular velocity was greater in the generalized joint laxity than in the non-generalized joint laxity group, and we observed a significant correlation between Beighton scores and the X-axis angular velocity. Furthermore, rotational angular velocity was positively correlated with anterior–posterior acceleration and extension angular velocity. [Conclusion] These findings suggest that rotational angular velocity of the tibia during knee extension is associated with generalized joint laxity in female university students.     

The effects of tibial rotation on the patellofemoral joint: assessment of the changes in in situ strain in the peripatellar retinaculum and the patellofemoral contact pressures and areas.

The objective of this study was to determine the effects of tibial rotation on in situ strain in the peripatellar retinaculum and patellofemoral contact pressures and areas. Patellofemoral joint biomechanics demonstrate a strong correlation with the etiology of patellofemoral disorders, such as chondromalacia, and are significantly influenced by tibial rotation. Six human cadaveric knees were used along with a patellofemoral joint testing jig that permits physiological loading of the knee extensor muscles. Patellofemoral contact pressures and areas were measured with a Fuji pressure-sensitive film, and the changes in in situ strain in the peripatellar retinaculum were measured with four differential variable reluctance transducers. Tibial rotation had a significant effect on patellofemoral joint biomechanics. The data showed an inverse relationship between increasing knee flexion angles and the change in patellofemoral contact pressures and in situ strain with tibial rotation. At higher knee flexion angles, the patella is well-seated in the trochlear groove and the function of the peripatellar retinaculum is minimized and less affected by tibial rotations.     

计算机导航与传统全膝关节置换疗效比较的Meta分析

背景：计算机辅助导航能否提高全膝关节置换假体的精确性及临床效果,一直存在很大争议。 目的：对国内外有关计算机辅助导航全膝关节置换的研究文献进行Meta分析,评价计算机辅助导航全膝关节置换与传统技术临床疗效的差异。 方法：计算机检索PubMed,Ovid,Elsevier,CNKI、数字图书馆等数据库,检索2005-01-01/2013-12-31有关计算机辅助导航与传统全膝关节置换临床效果随机对照试验的文献资料。采用 Cochrane 协作网提供的RevMan 5.0软件进行Meta分析,比较计算机辅助导航全膝关节置换与传统技术的临床疗效,并对数据进行异质性检验。 结果与结论：共纳入符合设计标准的16篇随机对照试验文献,导航组1322膝,传统组1299膝,导航组下肢力线内翻或外翻大于2°和3°的发生率、股骨胫骨假体冠状位对线内翻或外翻角大于3°的发生率、股骨假体矢状位对位线大于3°的发生率、胫骨后倾角大于3°的发生率均低于传统组。在胫骨假体矢状位对位线、股骨、胫骨假体内外旋转角度和并发症发生率两组差异无显著性意义。提示导航组能带来更佳的下肢力线和假体位置,但还需更多研究来提高远期效果。     

三维骨建模系统在人工全膝关置换中的优化用用:导肮与规手术早期疗效比较

背景:人工全膝关节置换手术的重点是准确的假体三维定位,重建良好的下肢力线,维持膝关节韧带的平衡,避免髌股关节并发症.从而取得一个无痛稳定、功能良好和持久耐用的关节.目的:通过对比导航和常规全膝关节置换的近期效果,讨论三维骨建模系统对人工全膝关节置换手术中精确重建下肢力线、旋转对位和韧带平衡的优化作用.设计:分组对比观察.单位:法国亨利蒙多医院矫形与创伤外科.对象:选择2002-11/2003-06在法国亨利蒙多医院矫形与创伤外科进行的计算机辅助人工膝关节置换21例为导航手术组,年龄64～79岁,14例膝内翻,7例膝外翻;常规手术人工膝关节置换20例传统手术组,年龄65～83岁,15例膝内翻,5例膝外翻:纳入标准均为的骨性关节炎患者,排除复治的人工全膝关节翻修术患者,患者均知情同意.方法:均采用后稳定型人工表面全膝关节(Hermes@法国Ceraver), 两组的手术基本操作相同,导航手术组在Ceravision@ 无需影像资料的三维骨建模(Bone-Morphing)计算机辅助系统监控下进行.主要观察指标:对比术前、术中和术后的相关影像资料,分析下肢力线重建和韧带平衡的结果;检查术后3个月手术膝关节的活动度、额面松弛度和髌骨稳定性.结果:41例患者均进入结果分析.①所有患者都获得人工膝关节胫、股骨假体的满意对位植入和韧带平衡.②Ceravision系统对下肢力线的测量及在膝内外翻应力下的测量均比X射线片更精确;两组病例的下肢力线都在内外翻3.的范围内(P>0.05).③两组术后3个月的关节活动度比较差异不显著(P=0.06);导航手术组膝关节额面松弛度优于常规手术组(P=0.03).④两组均无髌骨失稳和脱位等并发症.结论:应用以三维骨建模为基础的计算机辅助手术系统,优化了人工全膝关节置换,精确实现了截骨和三维对位,获得良好的膝关节屈伸位下关节等距间隙,保证良好的膝关节韧带张力与平衡稳定,取得比常规手术更合理的额面松弛度,术后的韧带平衡稳定更好.早期疗效满意.