A sagittal plane model of knee joint based on crossed-four-bar-linkage-based tibiofemoral joint model has been developed using geometric and force equilibrium constraints. The model predicts and explains the movement of contact point on the patella and femur, variation of patellar and patellar tendon angle, variation of patellar mechanism angle and variation of patellofemoral contact force and patellar tendon force. The computed results agree well with the published experimental results.
Biomechanical Phenomena ; Humans ; Knee Joint ; anatomy & histology ; physiology ; Models, Biological ; Movement ; physiology ; Patella ; anatomy & histology ; physiology

OBJECTIVETo propose a new method for automatic segmentation of manually determined knee articular cartilage into 9 subregions for T2 measurement.

METHODSThe middle line and normal line were automatically obtained based on the outline of articular cartilage manually drawn by experienced radiologists. The region of articular cartilage was then equidistantly divided into 3 layers along the direction of the normal line, and each layer was further equidistantly divided into 3 segments along the direction of the middle line. Finally the mean T2 value of each subregion was calculated. Bland-Altman analysis was used to evaluate the agreement between the proposed and manual subregion segmentation methods.

RESULTSThe 95% limits of agreement of manual and automatic methods ranged from -3.04 to 3.20 ms, demonstrating a narrow 95% limits of agreement (less than half of the minimum average). The coefficient of variation between the manual and proposed subregion methods was 4.04%.

CONCLUSIONThe proposed subregion segmentation method shows a good agreement with the manual segmentation method and minimizes potential subjectivity of the manual method.

Adult ; Cartilage, Articular ; anatomy & histology ; Humans ; Knee Joint ; anatomy & histology ; Magnetic Resonance Imaging ; methods ; Young Adult

BACKGROUNDSeveral techniques have been described for posterior cruciate ligament (PCL) reconstruction. However, double-bundle PCL reconstruction using the quadruple bone-tunnel technique has been seldom reported. The current study investigated this technique, focusing on the anatomy of the femoral and tibial insertions of the anterolateral (AL) and posteromedial (PM) bundles of the PCL.

METHODSTwenty-two fresh, healthy adult cadaveric knees were dissected and measured. The PCL was divided into the AL bundle and PM bundle at the insertion footprint. The insertion footprints of the AL and PM bundles, their location, size, and the clock positions were measured and described.

RESULTSOn the femur, the clock position of the footprint of the AL bundle was 11:21 ± 0:23 (left) or 0:39 ± 0:23 (right), and the PM bundle was 9:50 ± 0:18 (left) or 2:10 ± 0:18 (right), with the knee flexed at 90 degrees. The distances from the center of the femoral insertions of the AL and PM bundles to the anterior cartilage margins of the medial femoral condyle were (7.79 ± 1.22) mm and (8.36 ± 1.63) mm, respectively. On the tibia, the vertical distances from the center of the tibial insertions of the AL and PM bundles to the tibial articular surface were (3.25 ± 1.20) mm and (6.91 ± 1.57) mm, respectively.

CONCLUSIONSThese results have led to a better definition of the anatomy of the AL and PM bundle footprint of the PCL. The technique of double-bundle PCL reconstruction using quadruple bone-tunnel is feasible. Application of these data during PCL reconstruction using the quadruple bone-tunnel technique may help optimize knee stability.

Female ; Humans ; In Vitro Techniques ; Knee Joint ; anatomy & histology ; Male ; Posterior Cruciate Ligament ; anatomy & histology

PURPOSE: The purpose of this study was to evaluate the anatomical similarity of three-dimensional (3D) morphometric parameters between right and left knees. MATERIALS AND METHODS: Ten fresh-frozen paired cadaveric knees were tested. Following dissection, footprint areas of the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) were measured. Surface scanning was performed using a 3D scanner. Scanned data were reproduced and morphometric parameters were measured on specialized software. After making mirror models, we compared footprint center positions of the ACL and PCL of both sides and calculated the average deviation of 3D alignment between the right- and left-side models. RESULTS: No significant side-to-side differences were found in any morphometric parameters. Bony shapes displayed a side-to-side difference of < 1 mm. Distal femoral and proximal tibial volumes did not present side-to-side differences, either; the average 3D deviations of alignment between the right and left sides were 0.8±0.4/1.1±0.6 mm (distal femur/proximal tibia). Center-to-center distances between the right and left ACL footprints were 2.6/2.7 mm (femur/tibia) for the anteromedial bundle and 2.4/2.8 mm for the posterolateral bundle. They were 1.9/1.5 mm for the anterolateral bundle and 2.2/1.8 mm for the posteromedial bundle of the PCL. CONCLUSIONS: There was a remarkable 3D morphometric similarity between right and left knees. Our results might support the concept of obtaining morphologic reference data from the uninvolved contralateral knee.
Anatomy, Comparative ; Anterior Cruciate Ligament ; Cadaver ; Imaging, Three-Dimensional ; Knee Joint ; Knee ; Posterior Cruciate Ligament

Objective To explore the feasibility and clinical value of ultrasonography in evaluating the morphology and function of medial collateral ligaments (MCL) after total knee arthroplasty (TKA). Methods Totally 38 patients undergoing routine KTA (group A) and 22 patients undergoing constrained condylar knee arthroplasty KTA with MCL injury (group B) were included. Long axis views of MCL were taken and the MCL thickness was measured on femur side and tibial side 1 cm away from the joint line, respectively. The thicknesses were compared between the two groups. Subsequently, the gap between the metal part of the femoral prosthesis and the spacer after dynamic valgus stress was measured. The distribution and composition of the gap between the two groups were compared. Results High-frequency ultrasound clearly showed the prosthesis and MCL after TKA. MCL fiber structures of both groups were intact. The MCL thickness on the tibial side in group B was (0.25±0.06)cm, which was significantly thinner than group A [(0.32±0.14)cm] (t=2.12, P=0.040).For the femur side, there was no significant difference (t=1.65, P=0.110) between these two groups [(0.37±0.09) cm in group B versus (0.42±0.12)cm in group A]. Under the condition of valgus stress, the gaps between the metal part of the femoral prosthesis and the spacer could be found in 11 cases in group B but only in 1 case in group A. The proportion of gaps in group B was significantly higher than that in group A (Fisher's exact test, P=0.000). Conclusions High-frequency ultrasound can clearly show the prosthesis and MCL after TKA. The injured MCL can be well joined but the thickness is thinner. Under the condition of valgus stress of the knee, the stability of the TKA can be evaluated according to the gap between the prosthesis and the spacer.
Arthroplasty, Replacement, Knee ; Femur ; Humans ; Knee Joint ; Medial Collateral Ligament, Knee ; anatomy & histology ; diagnostic imaging ; physiology ; Tibia ; Ultrasonography

OBJECTIVETo investigate the T2 values and knee thickness in healthy young adults using 3.0 T magnetic resonance imaging(MRI) .

METHODSTotally 40 volunteers(18-30 years old) with body mass index between 18.5-24.0 kg/m(2) were divided into two groups(22 men and 18 women) according to their gender. Also in addition, each group was divided into two subgroups(right knee and left knee) . The T2 values and the thickness of the areas on the medial condyle of femur, the lateral condyle of femur, the medial tibial plateau, the lateral tibial plateau, and the patella of the knee cartilage were measured.

RESULTSThe T2 values and the thickness of the right and left knee cartilages showed no significant differences between men and women (P>0.05) . Also, the T2 values in the five parts of the knee cartilage also were not significantly different between men and women (P>0.05) . However, the thickness of the 5 parts of the knee cartilage significantly differed between men and women(P<0.05) .

CONCLUSIONSThe thickness of the knee cartilage may different between male and female young adults. The T2 values of the cartilage may be not affected by the gender.

Adolescent ; Adult ; Cartilage, Articular ; anatomy & histology ; Female ; Humans ; Knee Joint ; anatomy & histology ; Magnetic Resonance Imaging ; Male ; Sex Factors ; Young Adult

Ligaments are the main parts which stabilize the knee joint. How to analog the ligaments in biomechanical model will affect the characteristics of the human knee dynamics and in the computation of the stress in ligaments between two bones. This symposium is aimed at the survey of the simplified method of the ligaments via mechanical parameters, and providing an exact method of constructing model.
Biomechanical Phenomena ; Humans ; Knee Joint ; anatomy & histology ; physiology ; Ligaments, Articular ; anatomy & histology ; physiology ; Models, Anatomic ; Models, Biological

INTRODUCTIONThe end of medial opening oblique wedge high tibial osteotomy (HTO) points into a narrow area between the articular cartilage of the posterolateral proximal tibia and proximal tibiofibular joint (PTFJ) at the tibial site, which is an anatomical safe zone (ASZ) for osteotomy. We studied the ASZ and its relation to the fibular tip, including the level of posterior cruciate ligament (PCL) insertion, to avoid penetration into the knee and PTFJ, and PCL injury by osteotomy.

METHODSTen pairs of embalmed cadaveric legs were disarticulated at the knee joint and then examined. Soft tissues at the proximal tibia were removed. The posterior capsule of the PTFJ was incised to identify the articular cartilage of the PTFJ at the tibial site. The height of the fibular tip and the thickness of the ASZ were measured and calculated to determine the relationship between the ASZ and fibular tip. The level of PCL insertion was measured from the posterior articular surface of the proximal tibia to the distal attachment of the PCL.

RESULTSThe average height of the fibular tip and the thickness of the ASZ were 5.43 ± 1.53 mm and 4.12 ± 1.60 mm, respectively. On average, the fibular tip was 1.31 ± 1.28 mm higher than the ASZ, and the level of PCL insertion was 10.10 ± 1.88 mm.

CONCLUSIONTo ensure safety during medial opening oblique wedge HTO, the end of osteotomy should point accurately into the ASZ at a level just below the fibular tip as reference. Proximal osteotomy thickness should not be less than 10 mm at the level of PCL insertion.

Cadaver ; Cartilage, Articular ; surgery ; Fibula ; anatomy & histology ; Humans ; Knee ; anatomy & histology ; Knee Joint ; anatomy & histology ; Middle Aged ; Osteotomy ; instrumentation ; methods ; Posterior Cruciate Ligament ; anatomy & histology ; Tibia ; anatomy & histology ; surgery

Based on the biomechanical response of human knee joint to a front impact in occupants accidents, a finite element (FE) model of human knee joint was developed by using computer simulation technique for impacting. The model consists of human anatomical structure, including femoral condyle, tibia condyle, fibular small head, patellar, cartilage, meniscus and primary ligament. By comparing the results of the FE model with experiments of the knee joint in axial load conditions, the validation of the model was verified. Furthermore, this study provides data for the mechanical of human knee joint injury, and is helpful for the design and optimization of the vehicle protective devices.
Biomechanical Phenomena ; Finite Element Analysis ; Humans ; Knee Injuries ; physiopathology ; Knee Joint ; anatomy & histology ; physiology ; Models, Anatomic ; Models, Biological

At present, foreign standard knee joint prosthesis is mostly used in clinical practice; it can well represent the biological characteristic of knee joint on human being. So this paper adopts the reverse engineering technology in that connexion, presents novel positioning method of acquiring the point data on the surface of knee joint prosthesis, puts forward the algorithm of three-point angle method for removing the noise error and correcting the noise error based on the least squares plane to smooth point cloud. And then, the surface of knee joint prosthesis with better accuracy and smoothness can be generated. Finally, the knee joint prosthesis model can be generated. Thus, a basis is provided for the localization of knee joint prosthesis. This new algorithm is mainly used for the surface modeling based on point cloud smoothing, including the surface of knee joint prosthesis, the surface of regular shape, and the surface with gentle change in curvature.
Computer-Aided Design ; Humans ; Knee Joint ; anatomy & histology ; surgery ; Knee Prosthesis ; Prosthesis Design ; methods ; Prosthesis Fitting ; methods