ROTATION AND BRAKING STRATEGIES TO PERFORM A SUCCESSFUL CUTTING MANEUVER

This study aimed to reveal principle movement strategies during successful 90° cutting maneuvers (CMs). Investigation of the pelvis rotation angle showed that subjects mainly use two strategies: one with most of the 90° cutting angle already realized within the body rotation prior to the transition step or one with the rotation executed after transition. These different turning strategies also impacted the way subjects deflected their COM velocity. Pre-rotation results in a more effective movement and less injury risk while post-rotation is suggested to occur in unanticipated cutting maneuvers

A LOCAL APPROACH TO IDENTIFY THE IMPACT OF SUBJECT SPECIFIC MOVEMENT STRATEGIES ON THE LOCAL FORCES DURING CUTTING MANEUVERS

During multidirectional movements the body is not aligned with the global coordinate system (CS), complicating the interpretation of forces and moments. To overcome these issues, the global ground reaction force (GRF) was transformed into the CS of each segment and the orientation of the segments relative to the global CS were expressed in Euler angles (EA). Principle component analysis (PCA) was used to discriminate the wave forms of the local GRF and the EAs. The first three PC Eigenvectors of the EA and local GRF were correlated to determine the impact of the segment’s orientation on the GRF. An upright position of the shank and thigh segment increased the force acting medially on the knee. This potentially increases the risk of a varus movement, whereas a frontal tilt increased a laterally directed force that potentially stabilized the leg axis

COMPARING ESTIMATED AND MEASURED MUSCLE ACTIVATION DURING HIGHLY DYNAMIC AND MULTIDIRECTIONAL MOVEMENTS - A VALIDATION STUDY

The purpose of this study was to validate muscle activation of the lower extremities computed in AnyBodyMT with measured muscle activations (EMG) in highly dynamic movement tasks. Ten participants performed walking, jogging, sprinting and cutting tasks. Kinetic, kinematic and EMG data were captured for 8 muscles of the dominant leg. The average correlation coefficient (CC) was 0.51 (max.: 0.83, min.: -0.05) with 71% of all trials showing moderate to very good compliance. The average mean absolute error (MAE) was 1.32 (max.: 3.71, min.: 0.17). Co-contraction, precision of the muscle recruitment algorithm, electromechanical delay and anthropometrical measures may have affected the results. The estimation of computed muscle activation can be a suitable method for certain muscles considering highly dynamic movement tasks

Dynamic pressure analysis of novel interpositional knee spacer implants in 3D-printed human knee models

Alternative treatment methods for knee osteoarthritis (OA) are in demand, to delay the young (< 50 Years) patient’s need for osteotomy or knee replacement. Novel interpositional knee spacers shape based on statistical shape model (SSM) approach and made of polyurethane (PU) were developed to present a minimally invasive method to treat medial OA in the knee. The implant should be supposed to reduce peak strains and pain, restore the stability of the knee, correct the malalignment of a varus knee and improve joint function and gait. Firstly, the spacers were tested in artificial knee models. It is assumed that by application of a spacer, a significant reduction in stress values and a significant increase in the contact area in the medial compartment of the knee will be registered. Biomechanical analysis of the effect of novel interpositional knee spacer implants on pressure distribution in 3D-printed knee model replicas: the primary purpose was the medial joint contact stress-related biomechanics. A secondary purpose was a better understanding of medial/lateral redistribution of joint loading. Six 3D printed knee models were reproduced from cadaveric leg computed tomography. Each of four spacer implants was tested in each knee geometry under realistic arthrokinematic dynamic loading conditions, to examine the pressure distribution in the knee joint. All spacers showed reduced mean stress values by 84–88% and peak stress values by 524–704% in the medial knee joint compartment compared to the non-spacer test condition. The contact area was enlarged by 462–627% as a result of the inserted spacers. Concerning the appreciable contact stress reduction and enlargement of the contact area in the medial knee joint compartment, the premises are in place for testing the implants directly on human knee cadavers to gain further insights into a possible tool for treating medial knee osteoarthritis

Anaerobic ensiling of raw agricultural waste with a fibrolytic enzyme cocktail as a cleaner and sustainable biological product

The increasing expansion of agricultural activities have resulted in an unending production of agricultural waste which constitutes environmental nuisance, if not properly disposed. In most developing countries, this waste is burnt causing environmental problems and health challenges. The utilization of biodegraded ensiled agricultural waste, as an energy source, in livestock nutrition is proposed as a viable solution of reducing pollution. Agricultural waste such as straws is carbohydrate-rich materials that have a large potential as a dietary energy source for ruminants. This study aimed to determine the effect of anaerobic ensiling of raw agricultural waste with a fibrolytic enzyme cocktail as a cleaner and sustainable biological product for animal feed. Ten samples of 1 kg each of wheat straw, corn stalks and sugarcane bagasse were ensiled with enzyme cocktail at 0, 1 or 3 mL/kg dry matter of feed. Before ensiling, feed samples were chopped at 5 cm and moistened to a relative humidity of approximately 50% and then kept for 30 d in plastic bales. Feed type enzyme level interactions were observed (P < 0.01) for nutrient contents and fermentation kinetics. Increasing the level of enzyme cocktail increased (P < 0.01) crude protein and ether extract contents but decreased organic matter and non-structural carbohydrates contents of the three feeds. The enzyme cocktail also decreased (P < 0.01) neutral detergent fiber, acid detergent fiber, cellulose and hemicellulose contents of corn stalks and sugarcane bagasse. The high level of the enzyme cocktail increased (P < 0.05) methane production from corn stalks but decreased it from sugarcane bagasse. Fermentation parameters response to ensiling differed among the ensiled feeds. It can be concluded that anaerobic fermentation of enzyme-treated agricultural waste and feeding it to livestock is one of the viable ways of utilizing this waste which otherwise could have constituted nuisance and pollution to the environment, if incinerated or improperly disposed

Abnormal gait pattern in downhill hiking is related to muscular deficits of the knee flexors and extensors in active patients with total knee arthroplasty

Background To assess the in-field walking mechanics during downhill hiking of patients with total knee arthroplasty five to 14 months after surgery and an age-matched healthy control group and relate them to the knee flexor and extensor muscle strength. Methods Participants walked on a predetermined hiking trail at a self-selected, comfortable pace wearing an inertial sensor system for recording the whole-body 3D kinematics. Sagittal plane hip, knee, and ankle joint angles were evaluated over the gait cycle at level walking and two different negative slopes. The concentric and eccentric lower extremity muscle strength of the knee flexors and extensors isokinetically at 50 and 120°/s were measured. Findings Less knee flexion angles during stance have been measured in patients in the operated limb compared to healthy controls in all conditions (level walking, moderate downhill, steep downhill). The differences increased with steepness. Muscle strength was lower in patients for both muscle groups and all measured conditions. The functional hamstrings to quadriceps ratio at 120°/sec correlated with knee angle during level and downhill walking at the moderate slope in patients, showing higher ratios with lower peak knee flexion angles. Interpretation The study shows that even if rehabilitation has been completed successfully and complication-free, five to 14 months after surgery, the muscular condition was still insufficient to display a normal gait pattern during downhill hiking. The muscle balance between quadriceps and hamstring muscles seems related to the persistence of a stiff knee gait pattern after knee arthroplasty. LoE: III

Non-Sagittal Knee Joint Kinematics and Kinetics during Gait on Level and Sloped Grounds with Unicompartmental and Total Knee Arthroplasty Patients

<div><p>After knee arthroplasty (KA) surgery, patients experience abnormal kinematics and kinetics during numerous activities of daily living. Biomechanical investigations have focused primarily on level walking, whereas walking on sloped surfaces, which is stated to affect knee kinematics and kinetics considerably, has been neglected to this day. This study aimed to analyze over-ground walking on level and sloped surfaces with a special focus on transverse and frontal plane knee kinematics and kinetics in patients with KA. A three-dimensional (3D) motion analysis was performed by means of optoelectronic stereophogrammetry 1.8 ± 0.4 years following total knee arthroplasty (TKA) and unicompartmental arthroplasty surgery (UKA). AnyBody^™ Modeling System was used to conduct inverse dynamics. The TKA group negotiated the decline walking task with reduced peak knee internal rotation angles compared with a healthy control group (CG). First-peak knee adduction moments were diminished by 27% (TKA group) and 22% (UKA group) compared with the CG during decline walking. No significant differences were detected between the TKA and UKA groups, regardless of the locomotion task. Decline walking exposed apparently more abnormal knee frontal and transverse plane adjustments in KA patients than level walking compared with the CG. Hence, walking on sloped surfaces should be included in further motion analysis studies investigating KA patients in order to detect potential deficits that might be not obvious during level walking.</p></div

Knee adduction moments during level walking.

<p>Values are presented as mean curves (solid lines) ± standard deviations (SD, shaded areas). Positive values indicate adduction moments. Dotted lines represent the non-OP knee of the TKA group (red) and UKA group (blue). The green rectangle indicates significantly different peak values between the TKA-OP knee and CG (<i>p</i> = 0.001), the UKA-OP knee and CG (<i>p</i> = 0.007).</p

Interlimb differences in peak angles, moments, adduction moment impulses, transverse joint stiffness, FAP-CoM_add within the TKA and UKA-group.

<p>Interlimb differences in peak angles, moments, adduction moment impulses, transverse joint stiffness, FAP-CoM_add within the TKA and UKA-group.</p