In vivo determination of posterior femoral rollback for subjects having a NexGen posterior cruciate-retaining total knee arthroplasty

This study determines the in vivo kinematics during a deep-knee bend activity for subjects implanted with a posterior cruciate-retaining total knee arthroplasty having asymmetric geometries. Of 20 subjects, 19 experienced posterior femoral rollback (PFR) of the lateral condyle (average -3.9 mm), and 13 subjects experienced PFR of the medial condyle (average -3.1 mm). As a result of the lateral condyle rolling further posterior than the medial condyle, on average, subjects experienced 1.4 degrees of normal axial rotation. Of 20 subjects, 10 experienced normal axial rotation, whereas 10 experienced an opposite rotation pattern. Condylar lift-off occurred predominantly with the lateral condyle. Contrary to previous in vivo studies, the subjects in this study experienced consistent PFR of the posterior cruciate-retaining total knee arthroplasty. It can be hypothesized that having asymmetric femoral condyles may lead to PFR with increasing knee flexion.     

In vivo determination of posterior femoral rollback for subjects having a NexGen posterior cruciate–retaining total knee arthroplasty

This study determines the in vivo kinematics during a deep-knee bend activity for subjects implanted with a posterior cruciate–retaining total knee arthroplasty having asymmetric geometries. Of 20 subjects, 19 experienced posterior femoral rollback (PFR) of the lateral condyle (average −3.9 mm), and 13 subjects experienced PFR of the medial condyle (average −3.1 mm). As a result of the lateral condyle rolling further posterior than the medial condyle, on average, subjects experienced 1.4° of normal axial rotation. Of 20 subjects, 10 experienced normal axial rotation, whereas 10 experienced an opposite rotation pattern. Condylar lift-off occurred predominantly with the lateral condyle. Contrary to previous in vivo studies, the subjects in this study experienced consistent PFR of the posterior cruciate–retaining total knee arthroplasty. It can be hypothesized that having asymmetric femoral condyles may lead to PFR with increasing knee flexion.     

Arthroscopic partial meniscectomy of a posteriorly flipped superior leaflet in a horizontal medial meniscus tear using a posterior transseptal portal

This article describes a case of an arthroscopic partial meniscectomy of a posteriorly flipped superior leaflet in a horizontal medial meniscus tear using the posterior transseptal portal. An arthroscopic partial meniscectomy for bucket handle or flap tears in medial or lateral compartments using ordinary portals is a relatively common procedure in irreparable cases. However, the posterior compartment of the knee is not readily accessible through ordinary arthroscopic portals. Therefore, it has been considered a blind spot. Through the posterior transseptal portal, surgeons can achieve excellent arthroscopic visualization of the posterior compartment and easily perform arthroscopic procedures of the posterior compartment of the knee. A 48-year-old woman presented with a 1-year history of pain in the medial aspect of the right knee joint. Preoperative magnetic resonance imaging revealed a thinning of the medial meniscus posterior horn in coronal images and a sharp-edged triangle arising from the medial meniscus posterior horn between the medial femoral condyle and medial meniscus posterior horn on sagittal images (flipped-over sign). During the arthroscopic procedure, we found that the flipped leaflet was displaced posteriorly and was not mobile between the medial femoral condyle and medial meniscus posterior horn. Partial meniscectomy for a posteriorly displaced fragment can be performed successfully using the posterior transseptal portal. The posterior transseptal portal is useful for an arthroscopic partial meniscectomy of a posteriorly flipped leaflet in the posterior compartment of the knee.     

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。     

Detrimental kinematics of a flat on flat total condylar knee arthroplasty

Fourteen subjects having a flat on flat condylar posterior cruciate retaining total knee arthroplasty were evaluated under different in vivo weightbearing conditions, with six performing a deep knee bend and eight walking at normal gait. An interactive model fitting algorithm was used to convert two-dimensional fluoroscopic images into three-dimensional computer aided design solid model images. The femorotibial contact positions for the medial and lateral condyle started posterior at full extension. With a deep knee bend the lateral condyle acted as a pivot, and the medial condyle slid in the anterior direction. Five of six had lateral condyle liftoff (maximum 1.6 mm) and abnormal positive screw home motion was seen from 0 degree to 90 degrees flexion. During gait, all femorotibial contact positions were posterior in extension and throughout the cycle. Six of eight patients experienced lateral condyle liftoff (maximum 3.5 mm), but minimal screw home motion was seen. Abnormal medial condyle posteroanterior sliding, lateral condyle liftoff, and erratic screw home motion may be related to abnormal wear characteristics of this flat on flat condylar design.     

胫骨平台后髁骨折的治疗

目的:探讨胫骨平台后髁骨折的治疗方法。方法:9例胫骨平台后髁骨折患者,男6例,女3例;年龄24~58岁,平均36岁。左侧2例,右侧7例。骨折类型:后外侧髁骨折5例,后内侧髁骨折1例,双髁骨折3例,采用后内和(或)后外侧入路复位内固定治疗。结果:9例均获随访,随访时间6~32个月,平均18·4个月。患膝关节功能评定按Hohl评分标准:优7例,良2例。关节面未见明显塌陷情况。结论:膝关节的后内和(或)外侧入路较前侧入路能更充分暴露后关节间隙及胫骨平台后髁,为骨折的直视复位和植骨内固定提供了良好的操作空间。     

Enlarged post-operative posterior condyle tightens extension gap in total knee arthroplasty

We investigated whether the extension gap in total knee replacement (TKR) would be changed when the femoral component was inserted. The extension gap was measured with and without the femoral component in place in 80 patients with varus osteoarthritis undergoing posterior-stabilised TKR. The effect of a post-operative increase in the size of the femoral posterior condyles was also evaluated. The results showed that placement of the femoral component significantly reduced the medial and lateral extension gaps by means of 1.0 mm and 0.9 mm, respectively (p < 0.0001). The extension gap was reduced when a larger femoral component was selected relative to the thickness of the resected posterior condyle. When the post-operative posterior lateral condyle was larger than that pre-operatively, 17 of 41 knees (41%) showed a decrease in the extension gap of > 2.0 mm. When a specially made femoral trial component with a posterior condyle enlarged by 4 mm was tested, the medial and lateral extension gaps decreased further by means of 2.1 mm and 2.8 mm, respectively. If the thickness of the posterior condyle is expected to be larger than that pre-operatively, it should be recognised that the extension gap is likely to be altered. This should be taken into consideration when preparing the extension gap.     

胫骨平台后髁骨折的治疗

目的:探讨胫骨平台后髁骨折的治疗方法。方法:9例胫骨平台后髁骨折患者,男6例,女3例;年龄24⁵8岁,平均36岁。左侧2例,右侧7例。骨折类型:后外侧髁骨折5例,后内侧髁骨折1例,双髁骨折3例,采用后内和（或）后外侧入路复位内固定治疗。结果:9例均获随访,随访时间6³2个月,平均18·4个月。患膝关节功能评定按Hohl评分标准:优7例,良2例。关节面未见明显塌陷情况。结论:膝关节的后内和（或）外侧入路较前侧入路能更充分暴露后关节间隙及胫骨平台后髁,为骨折的直视复位和植骨内固定提供了良好的操作空间。     

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.     

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.     

Subsidiary lateral femoral condyle in arthrogryposis multiplex congenita

A previously undescribed anomaly of the distal femur occurred in a 3-month-old child with arthrogryposis multiplex congenita. There was a large boss of bone superior and posterior to the true lateral femoral condyle with which the lateral tibial femoral condyle articulated. To obtain full extension of the knee, it was necessary to perform a full posterior release and to replace the tibial condyle distally onto the true lateral condyle. The etiology of the anomaly remains conjectural, but the lesion should be sought for in patients with resistant flexion contracture requiring surgical release.     

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.     

Isolated chondral fractures of the knee

Eighteen patients with isolated chondral fractures of the knee were reviewed to reevaluate the clinical signs and symptoms. No other conditions had been present to account for the symptoms. Most of the patients had significant injuries often involving a flexed knee. All patients had had symptoms and physical findings strongly suggestive of meniscal abnormality. Roentgenographic examinations were noncontributory. The lesions occurred in four distinct patterns. All were full thickness. Many of the lesions occurred on the posterior aspect of a femoral condyle, a location where they could be easily overlooked if the condyle were not examined with the knee in extreme flexion. Abutment of the tibial spine against the medial femoral condyle may be one cause of these injuries. The incidence of isolated chondral fractures was found to be higher than previously reported. A negative arthroscopic meniscal examination in a patient with symptoms and physical findings suggestive of meniscal abnormality should alert the physician to the possibility of an isolated chondral fracture.     

In vivo comparison of femorotibial contact positions for press-fit posterior stabilized and posterior cruciate-retaining total knee arthroplasties

The objective of this study was to determine the in vivo medial and lateral femorotibial condyle contact positions for 20 subjects having either a posterior cruciate-retaining (PCR) or posterior-stabilized (PS) total knee arthroplasty (TKA) while sitting and kneeling. The two-dimensional radiographic images were converted into three-dimensional images using an iterative computer model-fitting technique. Anteroposterior contact positions, axial rotation, and condylar lift-off were assessed for each subject. In a seated position, the femorotibial contact points were, on average, posterior for both TKA groups (PCR: medial = -2.4 mm, lateral = -3.4 mm; PS: medial = -5.1 mm, lateral = -8.9 mm; medial, P=.21; lateral, P=.08). In a kneeling position, the contact position shifted anteriorly for the PCR TKA group (medial = 0.9 mm, lateral = -0.8 mm), whereas the contact positions in the PS TKA group remained posterior (medial = -5.6 mm, lateral = -8.3 mm; medial, P=.002; lateral, P=.0004). It is hypothesized that while in a kneeling position, the posterior cruciate ligament has less resistance to the anterior thrust of the femur relative to the tibia than in a PS TKA, in which this force is absorbed in the cam-and-post mechanism.     

Snapping popliteus tendon in a 21-year-old female

STUDY DESIGN: Case report. BACKGROUND: Determining the cause of painful snapping on the lateral aspect of the knee can be a challenge. The differential diagnosis includes iliotibial band friction syndrome, lateral meniscus tear, intra-articular loose body, discoid lateral meniscus, snapping biceps femoris tendon, degenerative joint disease, proximal tibiofibular joint instability, and snapping popliteus tendon. CASE DESCRIPTION: A 21-year-old female presented with a 7-year history of a painful snapping on the lateral aspect of her left knee. She reported the snapping occurred with all activities involving knee flexion and extension, including running and walking. With a diagnosis of snapping iliotibial band, she had received a variety of physical therapy interventions, including various lower extremity stretching and strengthening exercises. Nonsteroidal anti-inflammatory medications were also prescribed by her physician. Conservative and pharmoclogical interventions were unsuccessful in improving her symptoms. Similarly, our attempt with conservative treatment consisting of ice, taping, and a short period of immobilization was not successful. OUTCOMES: The patient underwent a surgical procedure consisting of removal of a prominent tubercle on the lateral femoral condyle and tenodesis of the popliteus tendon to the proximal aspect of the fibular (lateral) collateral ligament, followed by a postoperative program of physical therapy including range-of-motion and progressive strengthening exercises. At 6 weeks following surgery, the patient had returned to all activities with complete resolution of her symptoms. DISCUSSION: Painful snapping at the lateral aspect of the knee may be caused by a variety of disorders, including the popliteus tendon. Clinical diagnosis is challenging. Clinical suspicion of a snapping popliteus tendon as a source of the signs and symptoms of the condition is important for inclusion in the differential diagnosis. LEVEL OF EVIDENCE: Differential diagnosis, level 4.     

Kinematic comparison of posterior cruciate sacrifice versus substitution in a mobile bearing total knee arthroplasty

Interest in mobile bearing total knee arthroplasty (TKA) has increased significantly. The objective of this in vivo study was to analyze 2 different mobile bearing TKAs during gait and during a knee bend from 0 degrees to 90 degrees flexion. Femorotibial contact positions for 10 subjects, implanted by a single surgeon, were analyzed using videofluoroscopy. Five subjects were implanted with a posterior-stabilized mobile bearing TKA (PS), and 5 subjects were implanted with a posterior cruciate-sacrificing mobile bearing TKA (PCS). Each subject, while under fluoroscopic surveillance, performed 2 weight-bearing activities: i) normal gait and ii) deep-knee bend. This study showed that the kinematic patterns for subjects having either a PS or PCS mobile bearing TKA were similar during gait but different during a deep-knee bend. Subjects having a PS TKA experienced more posterior femoral rollback of the lateral condyle during the deep-knee bend. Findings of kinematic similarities in gait and differences in a deep-knee bend between these 2 mobile bearing designs are similar to previously published findings of fixed bearing posterior cruciate-retaining and PS TKA.     

Femoral rollback after cruciate-retaining and stabilizing total knee arthroplasty

Limited data comparing the kinematics of posterior cruciate ligament-retaining or substituting total knee arthroplasty with its own intact knee under identical loadings is available. In the current study, posterior femoral translation of the lateral and medial femoral condyles under unloaded conditions was examined for intact, cruciate-retaining, cruciate ligament-deficient cruciate-retaining and posterior-substituting knee arthroplasties. Cruciate-retaining and substituting total knee arthroplasties behaved similarly to the cruciate-deficient cruciate-retaining total knee arthroplasty between 0 degrees and 30 degrees flexion. Beyond 30 degrees, the posterior cruciate-retaining arthroplasty showed a significant increase in posterior translation of both femoral condyles. The posterior cruciate-substituting arthroplasty only showed a significant increase in posterior femoral translation after 90 degrees. At 120 degrees, both arthroplasties restored approximately 80% of that of the native knee. Posterior translation of the lateral femoral condyle was greater than that observed in the medial condyle for all knees, indicating the presence of internal tibial rotation during knee flexion. The data showed that the posterior cruciate ligament is an important structure in posterior cruciate-retaining total knee arthroplasty and proper balancing is imperative to the success of the implant. The cam-spine engagement is valuable in restoring posterior femoral translation in posterior cruciate-substituting total knee arthroplasty.     

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.     

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.