Multi-body optimization with subject-specific knee models: performance at high knee flexion angles

Validation of a multi-body optimization with knee kinematic models including ligament constraints

Knee Flexion Angle During Graft Fixation for Medial Patellofemoral Ligament Reconstruction: A Systematic Review of Outcomes and Complications

Potential Risks of Femoral Tunnel Drilling Through the Far Anteromedial Portal: A Cadaveric Study

There is a paucity of literature evaluating (1) changes in lateral compartment tibiofemoral contact mechanics and lateral meniscal function and (2) the effect of varying repair constructs in treating partial-thickness (type 3) lateral meniscal oblique radial tears (LMORTs). (1) Type 3 LMORTs would significantly alter lateral compartment contact mechanics and meniscal function when compared with the intact state, and (2) tibia-based suture anchor repair would more effectively restore these metrics to native levels when compared with capsular-based side-to-side repair or debridement. Controlled laboratory study. Eight nonpaired fresh-frozen human cadaveric knees were utilized for this study. Each specimen was tested across 5 states in the following order: intact lateral meniscus, LMORT type 3 (partial thickness) tear created 12 mm lateral to the root attachment, tibia-based suture anchor fixation, capsular-based side-to-side repair, and debridement. For each state, 4 knee flexion angles were tested in random order: 0°, 30°, 60°, and 90° with 500 N of axial load. The following were recorded for each state: contact area, mean contact pressure, peak contact pressure of the lateral compartment, lateral meniscal extrusion, and 3-dimensional lateral meniscal anterior root forces (via use of a novel 3-axis sensor). Differences in means of outcomes were compared by 2-way repeated measures analysis of variance. Type 3 LMORTs were associated with significantly increased contact pressures and extrusion at all flexion angles and decreased contact area at high knee flexion angles as compared with the intact state. The tear state was also associated with significantly decreased forces experienced at the lateral meniscal anterior root attachment versus the intact state. Tibia-based suture anchor and capsular-based side-to-side repair restored contact mechanics, extrusion, and anterior root forces to the intact state, with no significant difference between the repair conditions. Debridement was associated with worse or no better outcomes than tear state alone. In a cadaveric model, type 3 LMORTs significantly alter tibiofemoral joint mechanics and lateral meniscal force transmission, and repair of these tears restores the native state, regardless of repair construct. Clinically, this study provides biomechanical support for the repair of type 3 LMORTs at the time of anterior cruciate ligament reconstruction. This study provides data regarding the effects of type 3 LMORTs and LMORT repair on tibiofemoral contact mechanics and meniscal function. The results of our study provide additional biomechanical justification for LMORT repair at the time of anterior cruciate ligament reconstruction.

Soft tissue artifact (STA), the deformation of skin and muscle during motion, is known to be one of the important sources of errors in human motion analysis using stereophotogrammetry. As a way to reduce the STA errors, methods estimating positions of anatomical landmarks (AL) have been proposed that keep them rigidly related to the underlying bone. The previous methods [1,2] used intermediate variables such as joint angles or motion time to adjust AL positions which were calculated from position data of skin markers. The present study proposes a method to estimate AL positions with skin marker positions directly, thereby removing the intermediate variables of the previous methods. The proposed method identifies a systematic relationship between the displacements of ALs and skin markers relative to a technical coordinate frame defined by skin markers in ad hoc motions(Figure ​motions(Figure1).1). Then, AL positions are calibrated directly by using the displacement relationship with skin markers. The proposed method was applied to analyze three lower extremity motions (walking, sit-to-stand/stand-to-sit and step up/down) of ten healthy males. Its performance was compared with the transformation error minimization method (TEM) of [3] and the AL estimation method with joint angle (ALJ) of [2]. The proposed method considerably reduced STA errors relative to the TEM (by 30 – 80% ) and was also slightly more effective than the ALJ, showing 25 – 40% error reductions for seven of 18 kinematic variables(Figure ​variables(Figure22). Figure 1 Scatter plot of AL and skin marker displacement in the thigh of a participant Figure 2 Statistical comparison of compensation methods

Nemaline myopathy is a congenital neuromuscular disorder, which primarily affects the thin filaments. Clinically the most important feature is muscle weakness; however, this weakness is poorly understood. The present investigation aimed to determine the torque angle relationship of the knee extensor muscles during in vivo muscle contractions in a family with a novel phenotype of nemaline myopathy. The results of this study show that quadriceps weakness occurs predominantly at higher knee flexion angles, but relatively normal strength was found at angles closer to full knee extension. When the relative torque angle relationships were considered, torque loss at smaller than optimum knee flexion angle was greater in the patients compared with the controls. In addition, the optimum angle for maximal quadriceps torque production was shifted towards smaller knee flexion angles in the patients. This suggests that a weakness specifically at higher knee flexion angles probably occurs as a result of adaptations consequently to the disease. Furthermore, it is important to assess muscle function at different joint positions to allow adequate interpretation of muscle weakness.

Gait kinematics based on inertial measurement units with the sensor-to-segment calibration and multibody optimization adapted to the patient's motor capacities, a pilot study

Diverse marker sets and validation techniques have previously been utilized, posing challenges in comparing studies when assessing soft tissue artefacts in knee joint kinematics from motion analysis. This study aimed to analyse the data obtained from three different marker sets with the results derived from radiostereometric analysis (RSA) in measuring angular movements of the knee joint. Twelve post-knee replacement participants performed a one-leg step-down movement. Knee joint angular movements were analysed in flexion-extension, adduction-abduction, and internal-external rotation across all marker sets. The results were subsequently compared with those obtained from the RSA system using simple linear regression, a linear mixed-effects model, mean values and mean differences. All marker sets were found to systematically underestimate flexion-extension compared to RSA, with differences intensifying at higher knee flexion angles. The mean differences in the sagittal plane between RSA and the IOR marker set, progressively increased from approximately 5° (95% CI 4.3-4.9) to 15° (95% CI 11.6-17.9), reaching a maximum difference of 20° (95% CI 13.8-25.7) at 40° of knee flexion. Transverse and frontal plane data from all marker sets exhibited erratic errors compared to RSA. In summary, knee flexion-extension motions were consistent between marker sets, indicating minimal impact on results based on the marker set choice. However, all marker sets systematically underestimated skeletal motions in knee flexion-extension compared to RSA measurements. Data from the transverse and frontal planes were too inconsistent and therefore not reliable for use.

Human movement analysis is often performed with a model of multi-rigid-body system, whereby reflective-marker-based motion capture data are assimilated into the model for characterizing kinematics and kinetics of the movements quantitatively. Accuracy of such analysis is limited, due to motions of the markers on the skin relative to the underlying skeletal system, referred to as the soft tissue artifact (STA). Here we propose a simple algorithm for assimilating motion capture data during periodic human movements, such as bipedal walking, into models of multi-rigid-body systems in a way that the assimilated motions are not affected by STA. The proposed algorithm assumes that STA time-profiles during periodic movements are also periodic. We then express unknown STA profiles using Fourier series, and show that the Fourier coefficients can be determined optimally based solely on the periodicity assumption for the STA and kinematic constraints requiring that any two adjacent rigid-links are connected by a rotary joint, leading to the STA-free assimilated motion that is consistent with the multi-rigid-link model. To assess the efficiency of the algorithm, we performed a numerical experiment using a dynamic model of human gait composed of seven rigid links, on which we placed STA-affected markers, and showed that the algorithm can estimate the STA accurately and retrieve the non-STA-affected true motion of the model. We also confirmed that our STA-removal processing improves accuracy of the inverse dynamics analysis, suggesting the usability of the proposed algorithm for gait analysis.

The majority of musculoskeletal modelling studies investigating healthy populations use generic models linearly scaled to roughly match an individual’s anthropometry. Generic models disregard the considerable variation in musculoskeletal geometry and tissue properties between individuals. This study investigated the physiological implications of personalizing musculoskeletal model geometry (body segment mass, inertia, joint center, and maximum isometric muscle force). Nine healthy athletes performed ten repetitions of 15 meter sprints at 75–95% of their maximum sprinting speed and ten repetitions of unanticipated sidestep cut trials with a 4.5–5.5 m/s approach running speed. Structural magnetic resonance imaging was collected on the lower extremities, from which subject-specific musculoskeletal models were developed. A one-dimensional statistical parametric mapping paired t-test was used to compare generic and subject-specific musculoskeletal models for: lower-limb kinematics, kinetics, torque matching, as well as hamstrings, adductors, and quadriceps muscle activations and fiber dynamics. Percentage change of geometric parameters between generic and subject-specific models were determined. Compared to generic models, subject-specific models showed significantly lower ankle dorsi/plantar flexion angle during sprinting and several significantly different net joint moments during sprint and cut tasks. Additionally, subject-specific models demonstrated better torque matching, more physiologically plausible fiber lengths, higher fiber velocities, lower muscle forces, and lower simulated activations in a subset of investigated muscles and motor tasks. Furthermore, subject-specific models identified between-limb differences that were not identified with generic models. Use of subject-specific modeling, even in healthy populations, may result in more physiologically plausible muscle fiber mechanics. Implementing subject-specific models may be especially beneficial when investigating populations with substantial geometric between-limb differences, or unilateral musculoskeletal pathologies, as these are not captured by a generic model.

Elongation of the collateral ligaments after cruciate retaining total knee arthroplasty and the maximum flexion of the knee

In situ forces of the anterior and posterior cruciate ligaments in high knee flexion: an in vitro investigation

Controlled laboratory biomechanics study using a repeated-measures, counterbalanced design. To compare patellofemoral joint force and stress between a short- and long-step forward lunge both with and without a stride. Although weight-bearing forward-lunge exercises are frequently employed during rehabilitation for individuals with patellofemoral joint syndrome, patellofemoral joint force and stress and how they change with variations of the lunge exercise are currently unknown. Eighteen subjects used their 12-repetition maximum weight while performing a short- and long-step forward lunge both with and without a stride. Electromyography, ground reaction force, and kinematic variables were put into a biomechanical optimization model, and patellofemoral joint force and stress were calculated as a function of knee angle. Visual observation of the data show that during the forward lunge, patellofemoral joint force and stress increased progressively as knee flexion increased, and decreased progressively as knee flexion decreased. Between 70 degrees and 90 degrees of knee flexion, patellofemoral joint force and stress were significantly greater when performing a forward lunge with a short step compared to a long step (P<.025). Between 10 degrees and 40 degrees of knee flexion, patellofemoral joint force and stress were significantly greater when performing a forward lunge with a stride compared to without a stride (P<.025). When the goal is to minimize patellofemoral joint force and stress during the forward lunge performed between 0 degrees to 90 degrees knee angles, it may be prudent to perform the lunge with a long step compared to a short step and without a stride compared to with a stride, because patellofemoral joint force and stress magnitudes were greater with a short step compared to a long step at higher knee flexion angles and were greater with a stride compared to without a stride at lower knee flexion angles.

Standardization proposal of soft tissue artefact description for data sharing in human motion measurements.

Validity of an instrumented knee brace compared to 3D motion navigation: A cadaveric investigation