Pilot study on proximal femur strains during locomotion and fall-down scenario

Merge of motion analysis, multibody dynamics and finite element method for the subject-specific analysis of cartilage loading patterns during gait: differences between rotation and moment-driven models of human knee joint

“…Forward dynamics, in contrast, utilizes forces to determine model kinematics. These forces can be determined using contraction or joint rotation patterns computed via inverse dynamics [13]. Furthermore, we can factor bone flexibility into the analysis [14,15].…”

Neuro-musculoskeletal flexible multibody simulation yields a framework for efficient bone failure risk assessment

“…Thus, the logic extension to QCT-based FEA is the integration of patient-specific NMS dynamics. Clearly, the risk of bone fractures could be more accurately diagnosed with the complementation of NfMBS-predicted bone strength data under physiological-like representation with skeletal dynamics and soft tissue interaction 7,8 . NfMBS provides much deeper insight into relevant risk factors, as NMS dynamics—such as soft tissue damage or motor control dysfunctions—can be included into the set of boundary conditions to ultimately better resemble the patient-specific in-vivo situs.…”

“…As it concerns the neuro-muscular control, the computed muscle control algorithm may allow simulation of muscle-induced motion; however, the solution of using static optimization techniques for muscle distribution problems, although common in musculoskeletal multibody dynamics, is still a matter of debate in terms of neurophysiological evidence. In order to obtain dynamic stress and strain distributions for patient-specific and load case dependent scenarios, it is not only necessary to include bone-specific material properties but also subject-specific musculoskeletal architecture, i.e., muscle forces that act on the skeletal system as they would in-vivo 8 . Accomplishing this is still challenging as direct muscle force measurement is not possible and although statistical methods exist, automated implementation of musculoskeletal architecture is an unresolved problem 40 .…”

“…It is of major importance to reliably and rapidly obtain information on the dynamic in-vivo bone stresses and strains as these are fundamental parameters in mechanostat theory that characterizes the interplay between dynamic mechanical loading and musculoskeletal health 1 : Dynamic bone stresses and strains control bone remodeling 2,3 are indicators of bone fractures 2,4,5 and hence allow for tailored and monitored clinical treatment 6 . Additionally, dynamic stress analyses are essential to evaluate the mechanical properties of endoprosthetic implants in-situ during dynamic activities to improve implant design, implant durability and in turn, patient outcome 7,8 .…”

“…On the other hand, NMBS assumes bones as rigid bodies which makes the estimation of the field parameters stresses and strains impossible. In an attempt to resolve these issues, model reduction techniques have been employed within biomechanical FEA 8,41 . In the context of clinically relevant load cases that involve only small linear-elastic deformations, modally reduced flexible superelements models 42 (SEMs) were derived from finite-element models (FEMs) of bone segments and were implemented into NMS multibody models to allow for strain computation: Hughes et al .…”