Pelvic Rotation Is Associated With Asymmetry in the Knee Extensor Moment During Double-Leg Squatting After Anterior Cruciate Ligament Reconstruction

Asymmetry in knee extensor moment during double-leg squatting was observed after anterior cruciate ligament reconstruction, even after the completion of the rehabilitation program for return to sports. The purpose of this study was to clarify the association between asymmetry in the knee extensor moment and pelvic rotation angle during double-leg squatting after anterior cruciate ligament reconstruction. Twenty-four participants performed double-leg squatting. Kinetics and kinematics during squatting were analyzed using a 3-dimensional motion analysis system with 2 force plates. The limb symmetry index of knee extensor moment was predicted by the pelvic rotation angle (R2 = .376, P = .001). In addition, the pelvic rotation and the limb symmetry index of the vertical ground reaction force independently explained the limb symmetry index of the knee extensor moment (R2 = .635, P< .001, beta of pelvic rotation = -0.489, beta of vertical ground reaction force = 0.524). Pelvic rotation toward the involved limb was associated with a smaller knee extensor moment in the involved limb than in the uninvolved limb. The assessment of pelvic rotation would be useful for partially predicting asymmetry in the knee extensor moment during double-leg squatting. Minimizing pelvic rotation may improve the asymmetry in the knee extensor moment during double-leg squatting after anterior cruciate ligament reconstruction

The effects of relative trunk rotation velocity on ball speed and elbow and shoulder joint torques during baseball pitching

In baseball pitching, suppressing trunk rotation while rotating the pelvis in the early phase of arm cocking is important for throwing a fast ball. However, quantitative evaluation of trunk rotation during pitching has not been established, and its associations with elbow and shoulder torques are unclear. The purpose of this study was to examine the correlation of a new measure of trunk rotation suppression with ball speed and elbow and shoulder torques during pitching. Eighteen adult male baseball pitchers (21.7 +/- 1.2 years old) participated. Three qualified pitches were analysed using a three-dimensional motion capture system. Trunk rotation velocity, normalised to the peak velocity, was derived at the time of peak pelvic velocity. Pearson's correlation coefficient was used to determine correlations. The normalised trunk rotation velocity at the peak pelvic velocity was significantly correlated with elbow valgus torque (R = -0.508, P = 0.032), shoulder external rotation torque (R = -0.507, P = 0.032) and ball speed (R = -0.504, P = 0.033). A smaller normalised trunk rotation angular velocity at the time of peak pelvic rotation velocity could increase ball speed but may also increase elbow and shoulder torques among pitchers who demonstrate trunk rotation after foot contact

Larger hip external rotation motion is associated with larger knee abduction and internal rotation motions during a drop vertical jump

Associations among hip motions, knee abduction and internal rotation motion during a drop vertical jump (DVJ), which increases the risk of anterior cruciate ligament injury, remain unclear. The purpose of this study was to examine associations among knee abduction, internal rotation and hip joint motions during a DVJ. Fifty-seven young female participants performed a DVJ from a 30-cm height. Hip and knee kinematics and kinetics were analysed using a three-dimensional motion analysis system and force plates. Multiple regression analysis showed that peak knee abduction angle was negatively associated with knee internal rotation and hip internal rotation excursions from initial contact (IC) to peak knee flexion, and positively associated with peak knee abduction moment (R-2 = 0.465, P< 0.001). Peak knee internal rotation angle was negatively associated with the hip flexion excursion from IC to peak knee flexion and peak hip adduction moment (R-2 = 0.194, P= 0.001). In addition, hip internal rotation excursion was negatively associated with knee abduction and internal rotation excursion from IC to 50 ms after IC. To avoid a large knee abduction and internal rotation motion during jump-landing training, it might be beneficial to provide landing instructions to avoid a large hip external rotation motion

Functional assessment of the gluteus medius, cranial part of the biceps femoris, and vastus lateralis in Beagle dogs based on a novel gait phase classification

In humans, walking analysis based on the gait phase classification has been used for interpretation of functional roles of different movements occurring at individual joints, and it is useful for establishing a rehabilitation plan. However, there have been few reports on canine gait phase classification, and this is one of the reasons for preventing progress in canine rehabilitation. In this study, we determined phases of the canine gait cycle (GC) on the basis of the phase classification for human gait. The canine GC was able to be divided into initial contact (IC) and the following 5 phases: loading response (LR), middle stance (MidSt), pre-swing (PSw), early swing (ESw), and late swing (LSw). Next, the hind limb joint angles of the hip, stifle and tarsal joints and results of surface electromyography of the gluteus medius (GM), cranial part of the biceps femoris (CBF) and vastus lateralis (VL) muscles in relation to the gait phases were analyzed. The activities of three muscles showed similar changes during walking. The muscle activities were high in the LR phase and then declined and reached a minimum in the PSw phase, but they increased and reached a peak in the LSw phase, which was followed by the LR phase. In conclusion, the multiphasic canine GC was developed by modification of the human model, and the GC phase-related changes in the muscle activity and joint angles suggested the functions of GM, CBF and VL muscles in walking

Landing instructions focused on pelvic and trunk lateral tilt decrease the knee abduction moment during a single-leg drop vertical jump

Objectives: To investigate the effects of pelvic and trunk lateral tilt-focused landing instructions on the knee abduction moment during the single-leg drop vertical jump task. Design: Descriptive laboratory study. Setting: Motion analysis laboratory. Participants: Fifteen young, healthy female participants. Main outcome measures: The participants performed 15 single-leg drop vertical jumps. Landing in-structions with self-video recordings were provided so that the participants' pelvis and trunk remained horizontal in the frontal plane. Pelvic, trunk and knee kinematics and kinetics were evaluated using a three-dimensional motion analysis system before and after the landing instructions. Results: The peak knee abduction moment significantly decreased postinstruction (preinstruction 22.6 +/- 15.3 Nm, postinstruction 17.9 +/- 15.4 Nm, P = 0.004), as did pelvic and trunk lateral tilt (P < 0.01). The knee abduction and internal rotation angles at initial contact significantly decreased postinstruction (P = 0.037, P = 0.007), with no significant change in the peak knee abduction and internal rotation angles from pre-to postinstruction. Conclusions: Landing instructions focused on pelvic and trunk lateral tilt are effective in decreasing the knee abduction moment during the single-leg drop vertical jump. Pelvic and trunk lateral tilt should be controlled to decrease the knee abduction moment during single-leg landing

Kinematics and center of axial rotation during walking after medial pivot type total knee arthroplasty

Abstract Purpose In recent years, the medial pivot (MP) type total knee arthroplasty (TKA) implant has been developed and marketed for achieving more natural kinematics with MP. However, little is known about the pivot pattern during walking after MP type TKA. This study aimed to determine the kinematics and center of axial rotation during walking after MP type TKA. Methods This randomized prospective study enrolled 40 patients with MP type TKA, 20 with cruciate-substituting TKA (MP-CS group), 20 with posterior-stabilized TKA (MP-PS group), and 10 healthy volunteers (control group). The kinematics and center of axial rotation during overground walking were measured by a three-dimensional motion analysis system. The six-degrees-of-freedom kinematics of the knee were calculated by the point cluster method. Results The amount of change in knee flexion in early stance phase was significantly lower in the MP-CS and MP-PS groups than in the control group. The femur showed anterior translation during early stance phase in all three groups. The median center of axial rotation in the transverse plane was predominantly on the lateral side of the knee during stance in all groups. Conclusions Kinematics during gait are thought to be determined by physical posture, the kinetic chain during weight-bearing, and the kinematic features of adjacent structures, such as the behavior of the biarticular muscles. MP-CS and MP-PS did not necessarily induce rotational motion centered on the medial ball-in-socket component during walking; translational and lateral pivoting movements were also observed. Long-term follow-up is needed to monitor for polyethylene wear and implant loosening