Lower Limb Movement Pattern Differences Between Males and Females in Squatting and Kneeling

Research on the biomechanical characteristics of the tibiofemoral joint before and after kinematic alignment unicompartmental knee arthroplasty

BACKGROUND

Kinematic alignment (KA) unicompartmental knee arthroplasty (UKA), which has not been widely adopted in clinical practice, aims to implant a more personalized and physiologically compatible mobile-bearing UKA prosthesis for the treatment of advanced single compartment knee osteoarthritis. KA UKA is anticipated to enhance patient satisfaction and decrease the revision rate following UKA. However, its quantified biomechanical indicators remain unclear. The purpose of this study is to reveal the biomechanical characteristics of the tibiofemoral joint in normal and KA UKA knees, and to evaluate the biomechanical effect.

METHODS

In this study, six cadaveric knee joint specimens were utilized for biomechanical testing before (normal cadaveric knee joint specimen ) and after KA UKA. The knee joint specimens were subjected to an axial load of 1000 N, and the biomechanical parameters were assessed at flexion angles ranging from 0° to 120° in 10° increments.

RESULTS

The root mean square (RMS) values of the tibiofemoral contact area, mean contact pressure, and peak contact pressure during knee flexion were 529 mm², 1.8 MPa, and 4.5 MPa in normal knees, respectively. After KA UKA, these values changed to 449 mm², 2.0 MPa, and 9.8 MPa, respectively. Additionally, the RMS value of the external rotation of the femur relative to the tibia in the tibiofemoral joint was 9.9° in normal knees, while the posterior translations of the center of the femoral condyle, the medial femoral condyle, and the lateral femoral condyle were 18.4 mm, 11.5 mm, and 25.4 mm respectively. After KA UKA, these values changed to 8.6°, 19.3 mm, 12.9 mm, and 25.9 mm respectively.

CONCLUSION

At the same flexion angle, the increase in peak contact pressure in the medial compartment after KA UKA is the most significant compared with the normal knees. However, the kinematic characteristics do not change significantly after KA UKA. These findings are beneficial for understanding the possible postoperative complications and good functional effects of KA UKA.

Identification of movement phenotypes from occupational gesture kinematics: Advancing individual ergonomic exposure classification and personalized training

The identification of personalized preventive strategies plays a major role in contrasting the occurrence of work-related musculoskeletal disorders. This requires the identification of distinct movement patterns within large samples and the attribution of a proper risk level to each identified movement phenotype. We assessed the feasibility of this approach by exploiting wearable inertial measurement units to estimate the whole-body kinematics of 43 healthy participants performing 18 reach-to-manipulate movements, which differed based on the object's position in the space and the type of manipulation required. Through unsupervised clustering, we identified multiple movement phenotypes graded by ergonomic performance. Furthermore, we determined which joints mostly contributed to instantiating the ergonomic differences across clusters, emphasizing the importance of monitoring this aspect during occupational gestures. Overall, our analysis suggests that movement phenotypes can be identified within occupational motor repertoires. Assigning individual performance to specific phenotypes has the potential to inform the development of more effective and tailored interventions.

Effect of external load on muscle activation during the barbell back squat

AbstractThe aim of this study was to compare gluteus maximus-to-hamstring (GM:H) co-activation, hamstrings-to-quadriceps (H:Q) co-activation, and mean muscle activity in the vastus lateralis (VL), vastus medialis (VM), rectus femoris (RM), gluteus maximus (GM), semitendinosus (ST), and bicep femoris (BF) muscles across a range of training loads (40%, 50%, 50%, 70%, 80% 90% 1RM) of the barbell back squat in resistance trained females. Surface electromyography (EMG) was observed in 18 healthy resistance trained females for the VL, VM, RM, GM, ST, and BF during the ascending and descending phase of the back squat. During the ascending phase, the VL, VM, RM, GM, ST, and BF displayed significantly more EMG activation at 90% 1RM compared to 40%-70% (p < .03). During the descending phase, there were no significant differences displayed in mean muscle activity at 40%-80% of 1RM compared to 90% of 1RM. There were no significant differences in H-Q co-activation and GM-H co-activation during the ascending or descending phase across external loads. These findings are similar to the results found in similar studies using male participants and support that higher training intensities (80%-90% 1RM) of the barbell back squat significantly activate muscles surrounding the hip compared to lower loads (40%-70%). The results of this study also suggest that training intensities of 80% 1RM and 90% 1RM elicits the similar musculature activation in the muscle surrounding the hip in resistance trained females.