The in-vivo medial and lateral collateral elongation correlated with knee functional score and joint space following unicompartmental knee arthroplasty.

Background: The medial collateral ligament (MCL) and lateral collateral ligament (LCL) are paramount for joint stability. Their elongation patterns may change during fixed-bearing and mobile-bearing unicompartmental knee arthroplasty (FB and MB UKA). This study aims to explore the relationship between the elongation of MCL, LCL, and changes in joint space, as well as their correlation with functional scale scores during FB and MB UKA.

Optimal intersurface stability for unicompartmental femoral component design with two pegs placed on the distal resection surface: 5 mm peg length increment and 10° peg inclination.

Purpose: The present study aimed to identify the optimal design of the unicompartmental femoral component through parameter analysis and stability evaluation.

Methods: A finite element (FE) analysis was applied to analyse and adjust the parameter combinations of the anterior tilt angle of the posterior condyle resection surface, the position of the peg, the length of the peg and the inclination angle of the peg, resulting in 10 different FE models. Setting three knee flexion angles of 8.

Medial-pivot total knee arthroplasty enhances tibiofemoral axial rotation stability in weight-bearing mid-range flexion compared to posterior-stabilised system.

Purpose: Total knee arthroplasty (TKA) stands as a primary intervention for severe knee ailments, yet concerns remain regarding postoperative patient satisfaction and flexion instability. This study aims to evaluate the in-vivo kinematics of medial-pivot (MP) and posterior-stabilised (PS) designs during step-up activity, in comparison to the kinematics of the nonoperated contralateral knee.

Methods: Sixteen patients with PS-TKA and 14 with MP-TKA were retrospectively examined.

Safe bearing region for avoiding meniscal bearing impingement and overhang in mobile-bearing unicompartmental knee arthroplasty.

The purposes of this study were to propose a quantitative method of bearing overhang to minimize the effect of bearing spinning on mobile-bearing unicompartmental knee arthroplasty (MB UKA), suggest and apply safe bearing regions in daily activities. The overhang distance and area were calculated for neutral and spinning positions. The safe bearing regions were based on the relationship between bearing overhang and linear wear rate.

Race and Gender Differences in Anterior Cruciate Ligament Femoral Footprint Location and Orientation: A 3D-MRI Study.

Objective: The femoral tunnel position is crucial to anatomic single-bundle anterior cruciate ligament (ACL) reconstruction, but the ideal femoral footprint position are mostly based on small-sized cadaveric studies and elderly patients with a single ethnic background. This study aimed to identify potential race- or gender-specific differences in the ACL femoral footprint location and ACL orientation, determine the correlation between the ACL orientation and the femoral footprint location.

Methods: Magnetic resonance images (MRIs) of 90 Caucasian participants and 90 matched Chinese subjects were used for reconstruction of three-dimensional (3D) femur and tibial models.

Development and Validation of a Novel In Vitro Joint Testing System for Reproduction of In Vivo Dynamic Muscle Force.

In vitro biomechanical experiments utilizing cadaveric specimens are one of the most effective methods for rehearsing surgical procedures, testing implants, and guiding postoperative rehabilitation. Applying dynamic physiological muscle force to the specimens is a challenge to reconstructing the environment of bionic mechanics in vivo, which is often ignored in the in vitro experiment. The current work aims to establish a hardware platform and numerical computation methods to reproduce dynamic muscle forces that can be applied to mechanical testing on in vitro specimens.

Significant race and gender differences in anterior cruciate ligament tibial footprint location: a 3D-based analysis.

Background: The aim of the present study was to identify potential race- or gender-specific differences in anterior cruciate ligament (ACL) tibial footprint location from the tibia anatomical coordinate system (tACS) origin, investigate the distances from the tibial footprint to the anterior root of the lateral meniscus (ARLM) and the medial tibial spine (MTS), determine how reliable the ARLM and MTS can be in locating the ACL tibial footprint, and assess the risk of iatrogenic ARLM injuries caused by using reamers with various diameters (7-10 mm).

Patients And Methods: Magnetic resonance images of 91 Chinese and 91 Caucasian subjects were used for the reconstruction of three-dimensional (3D) tibial and ACL tibial footprint models. The anatomical coordinate system was applied to reflect the anatomical locations of scanned samples.

Larger Medial Contact Area and More Anterior Contact Position in Medial-Pivot than Posterior-Stabilized Total Knee Arthroplasty during In-Vivo Lunge Activity.

This study aimed to compare the in-vivo kinematics and articular contact status between medial-pivot total knee arthroplasty (MP-TKA) and posterior stabilized (PS) TKA during weight-bearing single-leg lunge. 16 MP-TKA and 12 PS-TKA patients performed bilateral single-leg lunges under dual fluoroscopy surveillance to determine the in-vivo six degrees-of-freedom knee kinematics. The closest point between the surface models of the femoral condyle and the polyethylene insert was used to determine the contact position and area.

Altered In Vivo Knee Kinematics and Lateral Compartment Contact Position During the Single-Leg Lunge After Medial Unicompartmental Knee Arthroplasty.

Background: Osteoarthritis (OA) progression in the lateral compartment is the most common reason for revision after medial unicompartmental knee arthroplasty (UKA). Altered contact kinematics in the lateral compartment may be related to the pathogenesis of OA.

Purpose: To quantify the in vivo 6 degrees of freedom (6-DOF) knee kinematics and contact points in the lateral compartment during a single-leg lunge in knees after medial UKA and compare them with the contralateral native knee.

Medial stability and lateral flexibility of the collateral ligaments during mid-range flexion in medial-pivot total knee arthroplasty patients demonstrates favorable postoperative outcomes.

Purpose: The objectives of the present study were to investigate the length change in different bundles of the superficial medial collateral ligament (sMCL) and lateral collateral ligament (LCL) during lunge, and to evaluate their association with Knee Society Score (KSS) following medial-pivot total knee arthroplasty (MP-TKA).

Methods: Patients with unilateral MP-TKA knees performed a bilateral single-leg lunge under dual fluoroscopy surveillance to determine the in-vivo six degrees-of-freedom knee kinematics. The contralateral non-operated knees were used as the control group.

Asymmetry of Posterior Condyles in Resection Plane and Axial Curvature for Total Knee Arthroplasty.

Objective: Understanding the morphology of the distal femur is essential for improving bone-implant match in total knee arthroplasty (TKA) and understanding the mechanisms behind knee kinematics. However, little is known about the asymmetry of the posterior condyles. Thus, this study aimed to thoroughly investigate asymmetries in sizes and shapes between the medial and lateral posterior condyles before and after femoral resections during TKA in osteoarthritic (OA) knees.

Glenoid Track Width Is Smaller Under Dynamic Conditions: An In Vivo Dual-Fluoroscopy Imaging Study.

Background: The glenoid track concept has been widely used to assess the risk of instability due to bipolar bone loss. The glenoid track width was commonly used as 83% of the glenoid width to determine if a lesion was on-track or off-track. However, the value was obtained under static conditions, and it may not be able to reflect the actual mechanism of traumatic dislocation during motion.

Distal Humeral Trochlear Geometry Associated With the Spatial Variation of the Dynamic Elbow Flexion Axis.

The complexity of the spatial dynamic flexion axis (DFA) of the elbow joint makes the elbow prosthesis design and humeral component alignment challenging. This study aimed to 1) investigate the variations of the spatial DFA during elbow flexion and 2) investigate the relationship between the distal humeral trochlear geometry and the spatial variation of the DFA. Ten healthy subjects participated in this study.

Protein-spatiotemporal partition releasing gradient porous scaffolds and anti-inflammatory and antioxidant regulation remodel tissue engineered anisotropic meniscus.

Meniscus is a wedge-shaped fibrocartilaginous tissue, playing important roles in maintaining joint stability and function. Meniscus injuries are difficult to heal and frequently progress into structural breakdown, which then leads to osteoarthritis. Regeneration of heterogeneous tissue engineering meniscus (TEM) continues to be a scientific and translational challenge.

Influence of the Anteromedial Portal and Transtibial Drilling Technique on Femoral Tunnel Lengths in ACL Reconstruction: Results Using an MRI-Based Model.

Background: In anatomic anterior cruciate ligament (ACL) reconstruction, graft placement through the anteromedial (AM) portal technique requires more horizontal drilling of the femoral tunnel as compared with the transtibial (TT) technique, which may lead to a shorter femoral tunnel and affect graft-to-bone healing. The effect of coronal and sagittal femoral tunnel obliquity angle on femoral tunnel length has not been investigated.

Purpose: To compare the length of the femoral tunnels created with the TT technique versus the AM portal technique at different coronal and sagittal obliquity angles using the native femoral ACL center as the starting point of the femoral tunnel.

An Efficient Needleless Grasping Suture Technique for Graft Preparation in Anterior Cruciate Ligament Reconstruction.

Objective: Several needleless techniques have been developed to outcome the inherent disadvantages of the traditional needle stitching technique for graft preparation, such as tendon damage through the needle, time consumption, and the potential risk of needlestick injury. The purpose of the present study is to compare the graft preparation time and the biomechanical performance between an efficient needleless technique and the traditional needle stitching technique for graft preparation in anterior cruciate ligament reconstruction (ACLR).

Methods: The time required to perform a complete suture on 20 hamstring tendons during ACLRs was measured.

Central femoral tunnel placement can reduce stress and strain around bone tunnels and graft more than anteromedial femoral tunnel in anterior cruciate ligament reconstruction.

The present study investigated the effects of anteromedial (AM) and central femoral footprint placement on stress and strain distribution around the femoral and tibial tunnel and graft following anterior cruciate ligament reconstruction (ACLR). A three-dimensional (3D) reconstructed knee model was validated and used for simulating ACLR by finite element analysis. A combined loading during normal human walking was applied to the knee models using different anatomic femoral tunnel placement at 20° knee flexion.

The Femoral Tunnel Drilling Angle at 45° Coronal and 45° Sagittal Provided the Lowest Peak Stress and Strain on the Bone Tunnels and Anterior Cruciate Ligament Graft.

The aims of this study were to 1) investigate the effects of femoral drilling angle in coronal and sagittal planes on the stress and strain distribution around the femoral and tibial tunnel entrance and the stress distribution on the graft, following anterior cruciate ligament reconstruction (ACLR), 2) identify the optimal femoral drilling angle to reduce the risk of the tunnel enlargement and graft failure. A validated three-dimensional (3D) finite element model of a healthy right cadaveric knee was used to simulate an anatomic ACLR with the anteromedial (AM) portal technique. Combined loading of 103.

Loss of Knee Flexion and Femoral Rollback of the Medial-Pivot and Posterior-Stabilized Total Knee Arthroplasty During Early-Stance of Walking in Chinese Patients.

The medial-pivot (MP) prosthesis was developed to produce more physiological postoperative knee kinematics and better patient satisfaction than traditional prostheses, but outcomes are inconsistent in different studies of Caucasian patients. This study aimed to investigate the postoperative patient satisfaction and knee kinematics of the MP and posterior-stabilized (PS) prosthesis during gait activity in Chinese patients. A retrospective analysis of 12 patients was received for this study in each MP group and PS group.

Well-Placed Acetabular Component Oriented Outside the Safe Zone During Weight-Bearing Daily Activities.

A comprehensive and thorough understanding of functional acetabular component orientation is essential for optimizing the clinical outcome after total hip arthroplasty (THA). This study aimed to quantify the functional acetabular anteversion and inclination of unilateral THA patients during walking and static standing and to determine whether the functional acetabular orientation falls within the Lewinnek safe zone. Seventeen patients with unilateral THA received a CT scan and dual fluoroscopic imaging during level walking and static standing to evaluate hip kinematics.

More Anterior Contact Position in Patients With Fixed-Bearing Unicompartmental Knee Arthroplasty During Daily Activities Than Wear Simulator.

Background: While wear simulation of unicompartmental knee arthroplasty (UKA) showed outstanding long-term wear performance, studies reported that polyethylene (PE) wear was responsible for 12% fixed-bearing (FB) UKA failure. This paper aimed to quantify the 6-degrees-of-freedom (6-DOF) knee kinematics and contact positions of FB UKA during daily activities and compare with the previous results of wear simulator.

Methods: Fourteen patients following unilateral medial FB UKA received a CT scan and dual fluoroscopic imaging during level walking, single-leg deep lunge, and sit-to-stand motion for evaluating 6-DOF FB UKA kinematics.

Accuracy of individualized 3D modeling of ossicles using high-resolution computed tomography imaging data.

Background: The present study aimed to investigate the visibility of small ossicle parts/landmarks on high-resolution computed tomography (HRCT)/3D reconstruction (3D) to investigate what improvements in scanning resolution are needed before accurate 3D printing of patient-specific ossicles is possible.

Methods: A total of 24 patients with sudden deafness sought consultation at the Department of Otorhinolaryngology Head and Neck Surgery at the Sixth Medical Center of People's Liberation Army General Hospital between October 2013 and June 2014 were enrolled in the study. All participants underwent a 256-slice spiral HRCT temporal bone axial scan, yielding a Digital Imaging and Communications in Medicine documents series.

Optimizing the Femoral Offset for Restoring Physiological Hip Muscle Function in Patients With Total Hip Arthroplasty.

Objective: Femoral offset (FO) restoration is significantly correlated with functional recovery following total hip arthroplasty (THA). Accurately assessing the effects of FO changes on hip muscles following THA would help improve function and optimize functional outcomes. The present study aimed to (1) identify the impact of FO side difference on the hip muscle moment arms following unilateral THA during gait and (2) propose the optimal FO for a physiological hip muscle function.