Amit M. Mane

Knee Kinematics During an In Vitro Simulated Deep Flexion Squat

Understanding the behavior of the natural knee in deep flexion can offer insight into the necessary design characteristics of a total knee implant. Andriacchi et al. [1] measured the in vivo characteristics of knee motion down to ∼150° knee flexion during a weight bearing squat. Likewise, Li et al. [2] investigated deep knee flexion in vitro using robotic technology during passive knee flexion. Both of these studies offer insight into the behavior of the knee in deep knee flexion; however, they have some limitations with regards to assessing physiological activities in a controlled manner. The purpose of this study was to measure the kinematics of the knee during a simulated in vitro deep knee squat so that in the future a dynamic, load-bearing, simulated deep knee squat could be used as a tool in the design of total knee prostheses.Copyright

In Vitro Simulation of Deep Knee Flexion Using Static and Dynamic Machines

Experimental testing with cadaveric tissue allows the application of controlled loads and/or motions while still maintaining the inherent variability in the anatomy and soft tissue of the specimens. Multi-axial dynamic loading of tissue allows for experiments to be conducted that simulate conditions approaching physiological. Knee simulators have been used to generate physiological loading on the human knee to study kinematics, soft tissue loading, and joint contact pressure. These machines have been used to investigate injury, surgical outcomes, and prosthetic design. While there are a number of different geometries for knee loading devices, most are based on the Oxford rig design [1] with a vertical orientation of the leg where the hip is able to translate up and down while allowing flexion at the hip, knee, and ankle. The foot or ankle can have a variety of constraints and degrees of freedom. One of the recent areas of interest in knee biomechanics is the role different structures of the knee play during deep knee flexion activities. This is of particular interest to the orthopedic industry because of the common complaint regarding a feeling of a loss of stability during high flexion activities for post-TKR patients and the prevalence of high-flexion activities in emerging worldwide markets. The objective of this abstract is to describe two knee loading devices that have been used to study knee biomechanics, and most recently high flexion motion, and present some representative data from these tools.Copyright

Change in Knee Passive Envelope of Motion With Total Knee Replacement Design

Many researchers have studied the tibial passive motion, the boundaries of which are defined by various knee ligamentious and bony constraints [1, 2, 3]. The technique has been used in clinical practices and experimental research to assess injury and predict likely surgical outcomes [1, 2]. After total knee replacement surgery (TKR), the implants’ design features and altered ligamentious tension provide the joint constraint and stability. Therefore, the change in passive envelope of motion from the natural condition could be used to observe the altered constraints and stability achieved in TKR knees. The objective of this study was to assess the change in passive envelope of motion after TKR with two implant designs: cruciate retaining and posterior stabilized.Copyright

Relationship Between Tibial and Femoral Bone Morphology and Soft Tissue Laxity of the Knee Using a PCA Model

Understanding morphological variations in bone has become an important topic, specifically for total knee arthroplasties (TKA). The need for implants to cater to differences in bone shape has been highly debated [1–2]. Equally important is understanding the relationship between bone shape and kinematic variations. Previous work has investigated the relationship of several anatomical measures on varus-valgus (VV) and internal-external (IE) laxity [3]. However, the relationship between VV and IE laxity is less understood. The first objective of this research was to understand the relationship between IE and VV laxity using a single principal component analysis (PCA) model. The second objective was to correlate the results of the laxity model with a more inclusive measure of shape variation using statistical shape modeling (SSM). The use of SSM allows for quantifications of variation between subjects to be expressed in a manner which provides a more thorough understanding of bone variation [4]. The purpose of this research was to identify the relationship between IE and VV laxity, and correlate those results with variations in bone morphology of the femur and tibia.© 2011 ASME

Evaluating Relationship Between Passive Knee Envelope and a Dynamically Simulated Walk

The motion patterns of the human knee joint depend on its passive motion characteristics, which are described by the ligamentious and articular constraints. Since active motions, like walking and squatting are believed to fall within a passive envelope, the basis for the understanding of the knee joint kinematics lies in the description of its passive constraint characteristics [1]. The link between the knee passive envelope and the kinematics during various dynamic activities has not been studied. It is unclear how the articular geometry and muscle activations of the knee influence the contribution of ligament constraints during dynamic activities. To explain the relationship between knee passive envelope and dynamic activities completely, new methodology must be developed. The objective of the present study was to estimate the effects of variation in passive knee envelope on the tibiofemoral kinematics during dynamically simulated gait using a multivariate analysis technique, principal component (PC) analysis.Copyright

Effect of Patellar Component Alignment in Total Knee Arthroplasty on Patellar Tracking During In Vitro Simulated Squat

Abnormal patellar tracking is one of the major causes of anterior knee pain and revision surgery after total knee arthroplasty (TKA)1. Patellar tracking after TKA results from several factors including component design, tissue balancing during TKA, shifting of the joint line, and alignment of the patellar and femoral prosthetic components, all of which can lead to anterior knee pain2. The purpose of this study was to observe in vitro the relationship between altered patellar tracking after TKA during a simulated squat activity and the alignment of the patellar component during TKA.Copyright

Identifying the Effects of Knee Anatomy Variation on the Envelope of Knee Motion (Varus-Valgus) Using Principal Components

The motion patterns of the human knee joint depend on its passive motion characteristics, which are described by the ligamentious and articular constraints. Since active motions, like walking and squatting are believed to fall within a passive envelope, the basis for the understanding of the knee joint kinematics lies in the description of its passive constraint characteristics [1]. Although several authors studied passive envelope characteristics of a knee, it is not clear from the literature which anatomical structures guide the knee in passive or active motion and how their geometric arrangement produces the unique path of passive knee motion [1–3]. A few mathematical models have been developed to study the structures that guide the passive knee motion [1, 2]. However, their hypotheses were not supported by a sufficiently detailed ligament bundle model, soft tissue properties, ligament insertion-origin sites and their intra-subject variability. To explain the relationship between knee anatomy and its variability with three-dimensional knee motion completely, new methodology must be developed. The objective of the present study was to estimate the effects of variation in knee anatomical factors on the tibiofemoral passive envelope using a multivariate analysis technique, principal component (PC) analysis.Copyright

Analysis of Natural Knee Rollback Using Lowest Point Method

During knee flexion and extension the ACL and PCL help to coordinate the movement and rotation of the knee by constraining the sliding and rolling motions at the joint. In the natural knee the femur pivots about the medial condyle and the femur tends to roll back on the tibia with increasing flexion [1]. The purpose of this study was to observe if and how rollback occurs in the natural knee using the lowest point (LP) method, and to understand how anterior-posterior (AP) motion is related to flexion angle in the natural knee. A better understanding of natural knee femoral rollback will influence future design of total knee arthroplasties.Copyright

Simulated Deep Flexion With Muscle Loading: Whole Leg Versus Knee Kinematics

Many activities of daily living during work, exercise, religious worship, and hobbies require deep knee flexion. Activities such as rising from a low chair or getting into or out of a bath require between 100° and 160° of knee flexion [1]. Other activities such as kneeling or squatting to pick an item off the ground can be difficult with a limited range of motion. Beside deep knee flexion being important for daily living activities, it is essential in non-Western cultures that commonly sit in deep knee-bending positions. In vitro studies looking at knee function often focus solely on the knee joint, ignoring the effect of the muscle, ligament, and tendon constraints of the ankle, and simplifying or neglecting muscle loads. The effects of these assumptions on kinematics are unknown. The purpose of this study was to compare a squatting activity for: 1) whole leg versus knee specimens, and 2) different combinations of quadriceps and hamstrings loading.© 2008 ASME

Deep Knee Activities: In Vitro Kinematic Measurements to Compare With In Vivo Studies

Deep knee flexion is required for many activities of daily living during work, exercise, religious worship, and hobbies. Walker et al. [1] found that activities such as rising from a low chair or getting into or out of bath require between 100° and 160° of knee flexion. Other activities such as kneeling or squatting to pick an item off the ground can be difficult with a limited range of motion. Beside deep knee flexion being important for daily living activities, it is essential in non-Western cultures that commonly sit in deep knee-bending positions.Copyright