Tibiofemoral Joint Kinematics Research Articles

Knee kinematics during staircase descent

The goal was to evaluate tibiofemoral knee joint kinematics during stair descent, by simulating the full stair descent motion in vitro. The knee joint kinematics were evaluated for two types of knee implants: bi-cruciate retaining and bi-cruciate stabilized. It was hypothesized that the bi-cruciate retaining implant better approximates native kinematics. The in vitro study included 20 specimens which were tested during a full stair descent with physiological muscle forces in a dynamic knee rig. Laxity envelopes were measured by applying external loading conditions in varus/valgus and internal/external direction. The laxity results show that both implants are capable of mimicking the native internal/external-laxity during the controlled lowering phase. The kinematic results show that the bi-cruciate retaining implant tends to approximate the native condition better compared to bi-cruciate stabilized implant. This is valid for the internal/external rotation and the anteroposterior translation during all phases of the stair descent, and for the compression-distraction of the knee joint during swing and controlled lowering phase. The results show a better approximation of the native kinematics by the bi-cruciate retaining knee implant compared to the bi-cruciate stabilized knee implant for internal/external rotation and anteroposterior translation. Whether this will result in better patient outcomes remains to be investigated.

Computer-based analysis of different component positions and insert thicknesses on tibio-femoral and patello-femoral joint dynamics after cruciate-retaining total knee replacement

BackgroundPositioning of the implant components and tibial insert thickness constitute critical aspects of total knee replacement (TKR) that influence the postoperative knee joint dynamics. This study aimed to investigate the impact of implant component positioning (anterior-posterior and medio-lateral shift) and varying tibial insert thickness on the tibio-femoral (TF) and patello-femoral (PF) joint kinematics and contact forces after cruciate-retaining (CR)-TKR. MethodA validated musculoskeletal multibody simulation (MMBS) model with a fixed-bearing CR-TKR during a squat motion up to 90° knee flexion was deployed to calculate PF and TF joint dynamics for varied implant component positions and tibial insert thicknesses. Evaluation was performed consecutively by comparing the respective knee joint parameters (e.g. contact force, quadriceps muscle force, joint kinematics) to a reference implant position. ResultsThe PF contact forces were mostly affected by the anterior-posterior as well as medio-lateral positioning of the femoral component (by 3 mm anterior up to 31 % and by 6 mm lateral up to 14 %). TF contact forces were considerably altered by tibial insert thickness (24 % in case of + 4 mm increase) and by the anterior-posterior position of the femoral component (by 3 mm posterior up to 16 %). Concerning PF kinematics, a medialised femoral component by 6 mm increased the lateral patellar tilt by more than 5°. ConclusionsOur results indicate that regarding PF kinematics and contact forces the positioning of the femoral component was more critical than the tibial component. The positioning of the femoral component in anterior-posterior direction on and PF contact force was evident. Orthopaedic surgeons should strictly monitor the anterior-posterior as well as the medio-lateral position of the femoral component and the insert thickness.

In Vivo Knee Kinematics in Patients With Arthrofibrosis After Anterior Cruciate Ligament Reconstruction

Context: Arthrofibrosis after anterior cruciate ligament (ACL) reconstruction can be detrimental to the knee joint function and patient outcomes. However, the effects of arthrofibrosis on the in vivo tibiofemoral and patellofemoral joint kinematics after ACL reconstruction remain unclear. Objective: The objective of this study was to quantify the in vivo knee kinematics during a dynamic lunge task in the knee with arthrofibrosis after ACL reconstruction. Methods: Eleven patients with arthrofibrosis in one knee after ACL reconstruction participated in this study. Computed tomography and dual fluoroscopic imaging were used to evaluate in vivo kinematics of affected and contralateral knees during a lunge task. Differences in 6 degrees of freedom tibiofemoral kinematics and patellar tracking between limbs were assessed via repeated-measures analysis of variance. Results: Internal tibial rotation (5.2° vs 7.5°, respectively; P < .001) and inferior patellar shift (24.6 mm vs 28.9 mm, respectively; P < .001) were significantly lower in the arthrofibrotic knee compared with the contralateral knee from 15° to 75° of knee flexion. The patella in the arthrofibrotic knee significantly less flexed by 9.1° (P = .009) throughout the measured ROM and less laterally tilted by 3° (P = .017) compared with the contralateral knee from 30° to 75° of knee flexion. Conclusions: A significant superior shift and medial tilt of the patella were found in the affected knee compared with those in the contralateral knee during the dynamic lunge. Decreased internal tibial rotation and patellar flexion were found in knees with arthrofibrosis following ACL reconstruction; whether these kinematic changes are caused by arthrofibrosis need further investigation.

Differences between men and women in coupled subtalar and tibiofemoral joint kinematics during gait revealed through dynamic biplane radiography

It has been suggested that subtalar and tibiofemoral kinematics are coupled, such that abnormal subtalar inversion during the impact and push-off portions of stance may affect tibial rotation, leading to abnormal compensatory knee motion. This study aimed to characterize tibiofemoral and subtalar coupled motion and to determine if sex-dependent differences exist in lower extremity coupled motion. Twenty young adults were imaged at 100 frames/s using dynamic biplane radiography while walking. Lower extremity CT scans were obtained and segmented into subject-specific 3D bone models. Digitally reconstructed radiographs generated from the models were matched to the biplane radiographs via a validated tracking process to obtain tibiofemoral and subtalar joint kinematics. Subtalar inversion/eversion was strongly associated with tibiofemoral internal/external rotation and tibiofemoral ab/adduction during impact and push-off (P < 0.001). Men reached neutral subtalar and tibiofemoral orientation at midstance, while women remained more inverted at the subtalar joint and more externally rotated at the tibiofemoral joint. The rate of tibiofemoral ab/adduction to subtalar eversion differed between sexes during push-off (P = 0.005). Women underwent subtalar inversion, as well as tibiofemoral internal rotation and adduction during push-off, while men underwent only subtalar inversion and tibiofemoral internal rotation, with effectively no tibiofemoral adduction. These results provide the first quantitative evidence characterizing subtalar and tibiofemoral coupled motion. Differences in coupled motion trajectories between men and women may be associated with the higher incidence of knee-related pathology in women. These novel findings may serve as a standard for comparison when evaluating patients with patellofemoral pain.

Medial congruent polyethylene design show different tibiofemoral kinematics and enhanced congruency compared to a standard symmetrical cruciate retaining design for total knee arthroplasty-an in vivo randomized controlled study of gait using dynamic radiostereometry.

New total knee arthroplasty implant designs attempt to normalize kinematics patterns that may improve functional performance and patient satisfaction. It was hypothesized that a more medial congruent (MC) anatomic bearingdesign (1) influences the tibiofemoral kinematics and (2) enhances articular congruency compared to a standard symmetrical cruciate retaining (CR) bearing design. In this double-blinded randomized study, 66 patients with knee osteoarthritis were randomly included in two groups: MC (n = 31) and CR (n = 33). Clinical characteristics such as knee ligament lesions and knee osteoarthritis scores were graded on preoperative magnetic resonance imaging and radiography. At the 1-year follow-up, dynamic radiostereometric analysis was used to assess tibiofemoral joint kinematics and articulation congruency. Patient-reported outcome measures, Oxford Knee Score, the Forgotten Joint Score, and the Knee Osteoarthritis Outcome Score, were assessed preoperatively and at the 1-year follow-up. Compared to the CR bearing, the MC bearing displayed an offset with approximately 3mm greater anterior tibial drawer (p < 0.001) during the entire motion, and up to approximately 3.5 degrees more tibial external rotation (p = 0.004) from mid-swing to the end of the gait cycle at the 1-year follow-up. Furthermore, the congruency area in the joint articulation was larger during approximately 80% of the gait cycle for the MC bearing compared to the CR. The patient-reported outcome measures improved (p < 0.001), but there were no differences between groups. In addition, there were no differences in clinical characteristics and there were no knee revisions or recognized deep infections during follow-up. The study demonstrates that the MC-bearing design changes tibiofemoral kinematics and increases the area of congruency towards more native knee kinematics than the CR bearing. In perspective this may contribute to a more stabilized knee motion, restoring the patient's confidence in knee function during daily activities.

Effect of Time After Injury on Tibiofemoral Joint Kinematics in Anterior Cruciate Ligament-Deficient Knees During Gait.

Background:Anterior cruciate ligament (ACL) injury can lead to changes in tibiofemoral kinematics during gait, but the detailed short-term kinematic changes after ACL injury are still unknown.Purpose:To measure tibiofemoral kinematics during gait in ACL-deficient (ACLD) knees over time after ACL injury.Study Design:Controlled laboratory study.Methods:The authors categorized 76 patients with unilateral ACLD knees into 4 groups based on the time from injury: <3 months (group 1), 3 to 6 months (group 2), >6 to 12 months (group 3), and >12 months (group 4). The controls were 20 participants with ACL-intact knees. Changes in the knee kinematics and range of motion during gait were compared among ACLD groups and those with ACL-intact knees.Results:Compared with controls, the range of motion of flexion in group 1 was significantly lower (6°; P = .033), and the mean knee flexion was significantly increased (0.7°-3.4°) in groups 1 to 4 (all P ≤ .004). There was more internal tibial rotation (2.9°-4.3°) in group 1 and 2, and more anterior tibial translation (4.3 mm) in group 1 during the stance or swing phases than in controls (P ≤ .049 for all). The mean internal tibial rotation and anterior tibial translation significantly decreased from group 1 to group 4 (P < .001 for both). Compared with controls, the mean medial tibial translation was significantly greater (1.2-2.5 mm) in all groups, and more medial tibial translations (2.4-3.7 mm) were observed during the stance phase in groups 1, 3, and 4 (P ≤ .047 for all).Conclusion:ACLD knees displayed a motion impairment walking strategy within 3 months, and a higher-flexion walking strategy increased with time after injury. Excessive anterior translation and internal rotation of the tibia tended to return to normal, while excessive medial translation of the tibia increased in ACLD knees after 6 months postinjury. These results may provide new insight into the compensatory mechanisms and risk factors for premature osteoarthritis in ACLD knees.

Effects of Weight-Bearing on Tibiofemoral, Patellofemoral, and Patellar Tendon Kinematics in Older Adults.

Quantification of natural knee kinematics is essential for the assessment of joint function in the diagnosis of pathologies. Combined measurements of tibiofemoral and patellofemoral joint kinematics are necessary because knee pathologies, such as progression of osteoarthritis and patellar instability, are a frequent concern in both articulations. Combined measurement of tibiofemoral and patellofemoral kinematics also enables calculation of important quantities, specifically patellar tendon angle, which partly determines the loading vector at the tibiofemoral joint and patellar tendon moment arm. The goals of this research were to measure the differences in tibiofemoral and patellofemoral kinematics, patellar tendon angle (PTA), and patellar tendon moment arm (PTMA) that occur during non-weight-bearing and weight-bearing activities in older adults. Methods: High-speed stereo radiography was used to measure the kinematics of the tibiofemoral and patellofemoral joints in subjects as they performed seated, non-weight-bearing knee extension and two weight-bearing activities: lunge and chair rise. PTA and PTMA were extracted from the subject’s patellofemoral and tibiofemoral kinematics. Kinematics and the root mean square difference (RMSD) between non-weight-bearing and weight-bearing activities were compared across subjects and activities. Results: Internal rotation increased with weight-bearing (mean RMSD from knee extension was 4.2 ± 2.4° for lunge and 3.6 ± 1.8° for chair rise), and anterior translation was also greater (mean RMSD from knee extension was 2.2 ± 1.2 mm for lunge and 2.3 ± 1.4 mm for chair rise). Patellar tilt and medial–lateral translation changed from non-weight-bearing to weight-bearing. Changes of the patellar tendon from non-weight-bearing to weight-bearing were significant only for PTMA. Conclusions: While weight-bearing elicited changes in knee kinematics, in most degrees of freedoms, these differences were exceeded by intersubject differences. These results provide comparative kinematics for the evaluation of knee pathology and treatment in older adults.

Pivot shift and Lachman test simulation-based exploration in juvenile populations for accurately predicting anterior tibial translation

Advancements in technology and finite element software have made it possible to develop simulation-based exploration of subject-specific tibiofemoral joint kinematics. In this study, the goal was to develop baseline knee models that accurately predict anterior tibial displacement when undergoing a Lachman and pivot shift test. A total of 22 subject-specific adolescent tibiofemoral joint finite element representations were developed using FEBio. The models were subject to loading conditions established in the literature to simulate the two clinical tests. Anterior tibial translations that were measured through clinical, historical controls were used to validate the proposed models. A 95% confidence interval showed that the simulated Lachman and pivot shift tests of the juvenile knee models were not statistically different from the historical controls and were in accordance with the anterior tibial translations that were measured experimentally. Clinically, simulations are important in advancing the field of knee finite element modeling, particularly in pediatric applications where the surgeon must balance restoring full function in a patient who is skeletally immature and where the growth plate is vulnerable. The methodologies created in developing these foundational models can be utilized to build more anatomically complex finite element representations that can both predict ligament stresses in response to dynamic activities and analyze the effects of different insertion sites.

Errors in using fixed flexion facet centers to determine tibiofemoral kinematics increase fourfold for multi-radius femoral component designs with early versus late decreases in the radius of curvature

BackgroundOne method to determine tibiofemoral joint kinematics following total knee arthroplasty (TKA) is to quantify movement of the anterior-posterior (AP) position of the flexion facet center (FFC) on each femoral condyle relative to the tibia during knee flexion. The primary objective was to determine how closely AP positions of fixed FFCs approximate AP positions of variable FFCs of multi-radius femoral component designs with early versus late initial transition angles (i.e. earliest flexion angle where the radius of curvature decreases markedly). MethodsVariable FFCs were determined for each femoral condyle as centers of best-fit circles to 20° segments of the sagittal profile from 0° to 120° of flexion in 15° increments. The fixed FFC of each condyle was the center of the best-fit circle from 0° to 120° of flexion. Errors in AP positions were differences between AP positions of fixed FFCs and variable FFCs. ResultsFor profiles with a late initial transition angle of 120° of flexion, the root mean square error (RMSE) was limited to 0.7 mm. For profiles with an early initial transition angle of 60° of flexion, the RMSE was 2.7 mm, nearly a fourfold increase. ConclusionsTo determine whether fixed FFCs can be used to indicate AP positions of femoral condyles with minimal RMSE < 1 mm, the initial transition angle should be found as an important first step. Condylar AP positions for designs with an early initial transition angle should not be approximated by AP positions of fixed FFCs when determining tibiofemoral kinematics.

Patients with knee osteoarthritis can be divided into subgroups based on tibiofemoral joint kinematics of gait – an exploratory and dynamic radiostereometric study

Patients with advanced knee osteoarthritis (KOA) frequently alter their gait patterns in an attempt to alleviate symptoms. Understanding the underlying pathomechanics and identifying KOA phenotypes are essential to improve treatments. We investigated kinematics in patients with KOA to identify subgroups of homogeneous knee joint kinematics. A total of 66 patients with symptomatic KOA scheduled for total knee arthroplasty and 15 age-matched healthy volunteers with asymptomatic, non-arthritic knees were included. We used k-means clustering to divide patients into subgroups based on dynamic radiostereometry-assessed tibiofemoral joint kinematics. Clinical characteristics such as knee ligament lesions and KOA scores were graded by magnetic resonance imaging and radiographs, respectively. We identified four clusters that were supported by clinical characteristics. The flexion group (n=20) consisted primarily of patients with medial KOA. The abduction group (n=17) consisted primarily of patients with lateral KOA. The anterior draw group (n=10) was composed of patients with medial KOA, some degree of anterior cruciate ligament lesion and the highest KOA score. The external rotation group (n=19) primarily included patients with medial collateral and posterior cruciate ligament lesions. Based on tibiofemoral gait patterns, patients with advanced KOA can be divided into four subgroups with specific clinical characteristics and different KOA-affected compartments. The findings add to our understanding of how knee kinematics may affect the patient's development of different types of KOA. This may inspire improved and more patient-specific treatment strategies in the future.

Gender differences in knee kinematics during weight-bearing knee flexion for patients with arthrofibrosis after anterior cruciate ligament reconstruction

BackgroundKnowledge of tibiofemoral and patellofemoral joint kinematics is important for understanding gender-related dimorphism in developing knee arthrofibrosis and advancement of related treatments. The objective of our study was to investigate gender differences existing in tibiofemoral kinematics and patellar tracking in patients with arthrofibrosis after anterior cruciate ligament (ACL) reconstruction during weight-bearing knee flexion.MethodsThe tibiofemoral and patellofemoral joint kinematics were measured in 30 patients (15 male and 15 female) with arthrofibrosis after ACL reconstruction during a lunge task, using computed tomography and dual fluoroscopic imaging system. These data were analyzed for gender differences.ResultsThe range of tibial rotation, patellar inferior shift, tilt, and flexion were significantly decreased in the affected knee compared to the contralateral knee from 15° to 75° of knee flexion (P ≤ 0.04). Statistically significant difference was detected for medial tibial translation between male and female patients at 60° (P = 0.04) and 75° of knee flexion (P = 0.02). The tibial rotation was significantly decreased at 60° (P = 0.03) and 75° of knee flexion (P < 0.01) in females. The inferior patellar shift in females was significantly lower than that in males at 15° (P = 0.04) and 30° of knee flexion (P = 0.01). The patellar tilt was significantly lower at 60° (P = 0.02) and 75° of knee flexion (P < 0.01) in females compared to males.ConclusionsThe results indicated a significant effect of gender on knee kinematics in patients with arthrofibrosis after ACL reconstruction during weight-bearing knee flexion. These gender differences in tibiofemoral kinematics and patellar tracking may warrant further investigations to determine implications for making gender-specific surgical treatments and rehabilitation programs.

On the Effect of Friction on Tibiofemoral Joint Kinematics

The effect of friction on nonlinear dynamics and vibration of total knee arthroplasties is yet to be investigated and understood. This research work aims at studying the influence of friction on nonlinear dynamics, friction-induced vibration, and damage of tibiofemoral joints. For this purpose, a spatial dynamic knee model is developed using an asymmetric nonlinear elastic model accounting for knee joint ligaments and a penalty contact model to compute normal contact stresses in the joint while contact detection is treated such that the associated computational time is reduced. Several friction models are considered and embedded in the dynamic model to estimate tangential friction forces in the knee joint. External loads and moments, due to the presence of all soft tissues, e.g., muscles and hip-joint reaction forces, applied to the femoral bone are determined using a musculoskeletal approach. In the post-processing stage, damage, i.e., wear and creep, are estimated using three wear models and an empirical creep formulation, respectively. In addition, a FFT analysis is performed to evaluate likely friction-induced vibration of tibiofemoral joints. Mesh density analysis is performed and the methodology is assessed against outcomes available in the literature. It can be concluded that friction influences not only the tribology, but also dynamics of the knee joint, and friction-induced vibration is likely to take place when the friction coefficient increases.

Accuracy Of 6dof Kinematics Of Tibiofemoral Joint Using High-speed Dfis Combined With 3d Mri Model

Cui Zhang1,2,3,Yu Liu2* and Shaobai Wang21Biomechanics Laboratory, College of Sports and Health, Shandong Sport University, Jinan, China. 2School of Kinesiology, Shanghai University of Sport, Shanghai, China. 3Sports Biomehanics Laboratory, Shandong Institute of Sport Science, Jinan, China.*Yu Liu, (Corresponding author) PURPOSE: To validate the precision, accuracy and consistency of 6DOF movement of Tibiofemoral Joint via a custom high-speed Dual plane Fluoroscopic Imaging System(DFIS) combined with 3D MRI model registration. METHODS: 5 copper beads were embed in tibial and femur of one fresh pig hind leg separately. 3D beads rigid model and 3D skeleton model were reconstructed based on CT and MRI images of the beads and the tibia and femur of the pig hind leg separately. Flexion and extension movement of pig leg were recorded by high-speed DFIS. The registration results of 3D beads rigid model was set as gold standard. Bias, SD of bias, Bland-Altman analysis and Pearson correlation analysis were used to test the precision, accuracy and consistency of 6DOF results of MRI bone model, compare with gold standard. RESULTS: The 6DOF kinematic results of tibiofemoral joint obtained by high speed DFIS combined with MRI 3D bone model registration method was highly correlated to the results obtained by gold standard (r > 0.917). The bias and SD of bias of the anterior-posterior, medial-lateral, superior-inferior transitions, and flexion-extension, varus-valgus, internal-external rotations of tibiofemoral joint were in sub-millimeter and sub-degree level. The mean D-value of 3D MRI bone model registration and gold standard results were uniformly distributed within the consistency interval. CONCLUSION: Combined high-speed DFIS with MRI images to reconstruct 3D skeleton model for registration is a method with high accuracy, precision and consistency, which can be used to measure clinical 6DOF movement and soft tissue contact characteristics of the tibiofemoral joint. Funding was provided by the National Nature Science Foundation of China 81702211; the Movement Science Research Innovation Team(2019-183).

Can Computer-Assisted Total Knee Arthroplasty Support the Prediction of Postoperative Three-Dimensional Kinematics of the Tibiofemoral and Patellofemoral Joints at the Replaced Knee?

The aim of this study was to analyze the extent to which postoperative patellofemoral joint (PFJ) kinematics assessed at 6-month follow-up after total knee arthroplasty (TKA) mimics the intraoperative kinematics after final component implantation. The study hypothesis, already proved in terms of tibiofemoral joint (TFJ) kinematics, is that the intraoperative assessment of PFJ kinematics after component implantation is also capable of predicting postoperative knee kinematics during activities of daily living. Twenty patients selected for TKA with patellar resurfacing were implanted using surgical navigation, including patellar component positioning via a novel computer-assisted procedure. This allowed for intraoperative TFJ and PFJ kinematic assessment after final component implantation. At 6-month follow-up, all patients were contacted for follow-up control; in addition to clinical examination, this implied postoperative kinematics assessments by three-dimensional video fluoroscopy of the replaced knee during standard activities of daily living. Several traditional PFJ, as well as TFJ, rotations and translations were calculated intra- and postoperatively and then statistically compared. Good postoperative replication of the intraoperative measurements was observed for most of PFJ variables analyzed, as well as those for TFJ. Relevant statistical analysis also supported the significant consistency between the intra- and postoperative measurements. Pertaining to the present findings on a statistical basis, intraoperative measurements performed at both TFJ and PFJ kinematics using a surgical navigation system under passive conditions, are predictive of the overall knee kinematics experienced at postoperative follow-ups by the same replaced knees in typical activities of daily living.

Shape is only a weak predictor of deep knee flexion kinematics in healthy and osteoarthritic knees

Tibiofemoral shape influences knee kinematics but little is known about the effect of shape on deep knee flexion kinematics. The aim of this study was to examine the association between tibiofemoral joint shape and kinematics during deep kneeling in patients with and without osteoarthritis (OA). Sixty-one healthy participants and 58 patients with end-stage knee OA received a computed tomography (CT) of their knee. Participants completed full flexion kneeling while being imaged using single-plane fluoroscopy. Six-degree-of-freedom kinematics were measured by registering a three-dimensional (3D)-static CT onto 2D-dynamic fluoroscopic images. Statistical shape modeling and bivariate functional principal component analysis (bfPCA) were used to describe variability in knee shape and kinematics, respectively. Random-forest-regression models were created to test the ability of shape to predict kinematics controlling for body mass index, sex, and group. The first seven modes of the shape model up to three modes of the bfPCAs captured more than 90% of the variation. The ability of the random forest models to predict kinematics from shape was low, with no more than 50% of the variation being explained in any model. Furthermore, prediction errors were high, ranging between 24.2% and 29.4% of the data. Variations in the bony morphology of the tibiofemoral joint were weakly associated with the kinematics of deep knee flexion. The models only explained a small amount of variation in the data with high error rates indicating that additional predictors need to be identified. These results contribute to the clinical understanding of knee kinematics and potentially the expectations placed on high-flexion total knee replacement design.

Influence of Variation in Sagittal Placement of the Femoral Component after Cruciate-Retaining Total Knee Arthroplasty.

Prosthetic alignment is an important factor for long-term survival in cruciate-retaining (CR) total knee arthroplasty (TKA). The purpose of this study is to investigate the influence of sagittal placement of the femoral component on tibiofemoral (TF) kinematics and kinetics in CR-TKA. Five sagittal placements of femoral component models with -3, 0, 3, 5, and 7 degrees of flexion are developed. The TF joint kinematics, quadriceps force, patellofemoral contact force, and posterior cruciate ligament force are evaluated using the models under deep knee-bend loading. The kinematics of posterior TF translation is found to occur with the increase in femoral-component flexion. The quadriceps force and patellofemoral contact force decrease with the femoral-component flexion increase. In addition, extension of the femoral component increases with the increase in posterior cruciate ligament force. The flexed femoral component in CR-TKA provides a positive biomechanical effect compared with a neutral position. Slight flexion could be an effective alternative technique to enable positive biomechanical effects with TKA prostheses.

Dual fluoroscopic evaluation of human tibiofemoral joint kinematics during a prolonged standing: A pilot study

A complete knowledge of tibiofemoral joint kinematics is essential for understanding the function of the healthy and pathological joint. The objective of the present study was to establish a dual fluoroscopic measurement protocol and a data processing approach for the creep response of the knee joint in order to further evaluate the mechanical properties of articular cartilage and meniscus in vivo. A computational approach was developed for the determination of 3D translations and rotations of the joints of young participants with no history of injury using dual fluoroscopic images of loaded joints and joint geometry reconstructed from magnetic resonance imaging of the unloaded joints. High-resolution X-ray images were obtained for the distal femur and proximal tibia during 10-min standing when approximately ¾ body weight was slowly applied to the right leg and then kept constant for the rest duration of the test. Anatomic coordinate systems were established for the 3D models of distal femur and proximal tibia. Translations and rotations of the joint as functions of time were then evaluated using the X-ray images and these coordinate systems with the JointTrack software. The displacements in the proximal-distal direction obtained from two participants were consistent, showing a substantial increase in the initial phase when joint loading increased from nil to ¾ body weight and a continued small increase over time while the joint loading remained constant. The maximum anterior-posterior translations during 10-min standing were approximately 4 mm for both participants, although one showed better stability than the other. In conclusion, a creep loading protocol of the knee joint can be reasonably established for in vivo conditions and evaluated with the image-based computational approach.

How prosthetic design influences knee kinematics: a narrative review of tibiofemoral kinematics of healthy and joint-replaced knees

ABSTRACTIntroduction: To improve the total knee arthroplasty (TKA) prosthesis design, it is essential to study the kinematics of the tibiofemoral joint. Many studies have been conducted in this area; however, conflicting results and incomparable testing methods make it difficult to draw definitive conclusions or compare research from studies. The goal of this article is to introduce what is known about both healthy and prosthetic tibiofemoral joint kinematics.Areas covered: Healthy tibiofemoral joint kinematics are reviewed in vivo by different activities, and the kinematics of existing knee prosthetic design features are considered separately. These features include but are not limited to cruciate retaining, posterior cruciate substituting, mobile-bearing, and high flexion.Expert commentary: The type of activity that is being performed has a great influence on the kinematics of healthy knees, and the influences of different TKA prosthetic design features on the kinematics are complex and varied. Moreover, the TKA postoperative functional performance is influenced by many factors, and prosthetic design is among them, but not the only one that defines the performance.

Biomechanical Evaluation of Isotropic and Shell-Core Composite Meniscal Implants for Total Meniscus Replacement: A Nonlinear Finite Element Study

Loss of meniscal function due to symptomatic meniscal tears or meniscectomy leads to biomechanical instability and articular cartilage degeneration. Synthetic meniscal implants ought to ideally restore normal joint contact mechanics and thus forfending the overlying cartilage from degeneration. The purpose of this study was to quantify the contact stresses in both tibiofemoral compartments and joint kinematics during a gait cycle after implantation of a synthetic meniscal implant. Anatomically-detailed finite element model of the knee joint was developed from magnetic resonance images of a healthy female volunteer. Gait analysis was conducted using a three-dimensional motion capture system and computed the knee joint forces and moments and quadriceps muscle forces for a complete walking cycle. The effects of a synthetic meniscal implant on joint mechanics during gait were studied by conducting finite element simulations for the following meniscus conditions: (i) intact meniscus, (ii) meniscus with complete radial posterior root tear, (iii) total meniscectomy, (iv) isotropic meniscal implant, and (v) shell-core composite meniscal implant. Posterior root tear and total meniscectomy caused substantially increased contact stresses in both tibiofemoral compartments and altered tibial kinematics. Compared to posterior root tear and total meniscectomy, the isotropic and composite meniscal implants reduced the peak contact stresses in both compartments and reduced the cartilage nodes with higher contact stresses by disseminating the load over a large surface area. The shell-core composite meniscal implant resulted in lower contact stresses in the medial compartment relative to the other meniscus conditions. This study demonstrated that posterior root tear and total meniscectomy leads to detrimental changes in joint mechanics. Superseding the injured meniscus with a synthetic meniscal implant restored the joint mechanics close to the intact meniscal state. This novel synthetic meniscal implantation approach appears to be a promising strategy for treating patients with severe meniscal injuries.

Flexed femoral component improves kinematics and biomechanical effect in posterior stabilized total knee arthroplasty.

The kinematics and biomechanics of the knee joint are important in ensuring patient satisfaction and functional ability after total knee arthroplasty (TKA). There has been no study on knee joint mechanics with regard to the sagittal alignment of the femoral component. The objective of this study is to determine the extent of the impact of the femoral component's sagittal alignment on kinematics and biomechanics. A validated computational TKA model was used. The femoral component was simulated at - 3°, 0°, 5°, and 7° of flexion in the sagittal plane. This study evaluated the tibiofemoral (TF) joint kinematics, contact point, quadriceps force, and contact stress on the patellofemoral (PF) joint under a deep-knee-bend condition. The kinematics of the TF joint in the posterior direction increased with the flexion of the femoral component position. For all tasks, the overall posterior locations of the TF contact points were observed in the medial and lateral compartments as the femoral component flexion angle increased. The quadriceps force and contact stress on the PF joint decreased with the femoral component flexion. This study found that the femoral component sagittal position is an important factor in knee joint mechanics. In this study, the flexion of femoral component showed a stable reconstruction of the knee extensors' mechanism. Surgeons may consider neutral-to-mild flexed femoral component position, without concerns of anterior notching of the femoral cortex.