Hip Angle Changes Research Articles

Synchronized acoustic emission and gait analysis of total hip replacement patients

ObjectiveIncreased numbers of joint replacement patients suffering implant wear and/or loosening has created a need for development of non-invasive early diagnosis techniques. Acoustic emission monitoring has shown diagnostic potential for joint replacements, but has not previously been linked to temporal stages of the gait cycle, biomechanical modelling, and hip flexion angles. This combination of acoustic and biomechanics parameters is the novel contribution of this manuscript. MethodsTotal hip replacement acoustic emissions are synchronized with gait data using three-dimensional video motion capture from total hip replacement patients. Hip joint motions are estimated from the motion data, using OpenSim musculoskeletal modelling software, synchronized in time with the recorded acoustic emission data. ResultsSubstantial acoustic emissions have been observed occurring only during the stance phase of the gait cycle in two of three patients. Repeated audible squeaking was observed from one patient during terminal stance. Squeaking was observed to occur from approximately 5°-15° hip extension when high joint loading and rapid changes in hip angle were occurring. These are also the likely conditions of the largest implant bearing surface wear rates. ConclusionSpecific regions within the gait cycle that peak acoustic emission signals occur are identified, providing insight into underlying biomechanics. High implant load and high angular velocity during the stance phase are correlated with peak acoustic emissions. SignificanceThis is one of the first studies to relate recorded in-vivo human implant acoustic emissions with lower-limb biomechanical modelling, providing new insight into in-vivo total hip replacement implant mechanics. Further research is needed to increase patient numbers and verify if these results apply more broadly to a wider cohort.

Negligible epimuscular myofascial force transmission between the human rectus femoris and vastus lateralis muscles in passive conditions.

There have been contradictory reports of the effects of epimuscular myofascial force transmission in humans. This study investigated the transmission of myofascial force to the human vastus lateralis muscle by determining whether vastus lateralis slack angle changed with hip angle. Since the distance between the origin and insertion of the vastus lateralis muscle does not change when hip angle changes, any change in vastus lateralis slack angle with hip position can be attributed to epimuscular myofascial force transmission. Nineteen young adults were tested in hip flexed ([Formula: see text]) and neutral ([Formula: see text]) positions. Ultrasound images of the vastus lateralis muscle were obtained as the knee was passively flexed at [Formula: see text]/s. The knee angle at which vastus lateralis muscle fascicles began to lengthen was used to identify muscle slack angle. Overall, there was a negligible effect of hip position on vastus lateralis slack angle ([Formula: see text] [[Formula: see text] to 1.9]; mean [95% confidence interval]). However, a small and variable effect was noted in 3/19 participants. This result indicates that, over the range of joint angles tested here, there is little or no epimuscular myofascial force transmission between the vastus lateralis muscle and neighbouring bi-articular structures under passive conditions. More broadly, this result provides additional evidence that epimuscular myofascial force transmission tends to be small and variable under passive conditions in healthy human muscle.

THE INFLUENCE OF HIP JOINT ANGLE ON THE RATIO BETWEEN ADDUCTION AND ABDUCTION TORQUE IN EXPERIENCED, RECREATIONAL MALE ICE HOCKEY PLAYERS

Strains of the adductor muscle group of the hip are common amongst ice hockey players. The ratio of isometric strengths between the hip adductors and abductors has been offered as a risk factor for hip adductor strain; however, there is no description for how the ratio between hip adductor and abductor strength varies as a function of hip abduction angle. The aim of this study was to determine the influence of hip joint abduction angle on measured ratios of hip adduction to abduction torque in experienced, recreational, male hockey players. The primary null hypothesis for this study was that hip joint abduction angle would not influence hip adduction-to-abduction torque ratios in male hockey players. Counterbalanced observational cohort. Twelve uninjured, male, recreational hockey players, with a minimum experience level of midget AAA/minor competitive or equivalent. Participants performed maximal isometric side-lying hip adduction and abduction exertions against a rigidly constrained load cell at 0, 10, and 20 degrees of hip abduction. Measured peak torques from each exertion were used to derive the hip adductor-to-abductor torque ratio. Kinematics of the trunk, pelvis, and lower limbs were monitored using an optoelectronic motion capture system. Adductor-to-abductor torque ratio increased from 1.49 (SD = 0.20), to 1.92 (SD = 0.20) and to 2.30 (SD = 0.54) with successively increasing hip abduction angle (p < 0.001). Peak torque was significantly different between all angles (p ≤ 0.016) except between adduction exertions performed at 10 and 20 degrees of abduction (p = 0.895). Small changes in hip angle during the exertion were coincident with exertion direction, which confirmed the isometric nature of the task. Hip abduction angle has a significant impact on the measured adductor-to-abductor torque ratio. The ratio increased due to a combination of increased adductor torque and decreased abductor torque as the hip abduction angle increased. 2b.

The limits of aerial and contact techniques for producing twist in reverse 1½ somersault dives

An angle-driven computer simulation model of aerial movement was used to determine the maximum amount of twist that can be produced in a reverse 1½ somersault dive from a three-metre springboard using various aerial and contact twisting techniques. The segmental inertia parameters of an elite springboard diver were used in the simulations and lower bounds were placed on the durations of arm and hip angle changes based on recorded performances of twisting somersaults. A limiting dive was identified as that producing the largest possible odd number of half twists. Simulations of the limiting dives were found using simulated annealing optimisation to produce the required amounts of somersault, tilt and twist after a flight time of 1.5 s. Additional optimisations were then run to seek solutions with the arms less adducted during the twisting phase. It was found that the upper limits ranged from 3½ to 5½ twists with arm abduction ranges lying between 8° and 23°. Similar results were obtained when the inertia parameters of two other springboard divers were used. It may be concluded that a reverse 1½ somersault dive using aerial asymmetrical arm and hip movements to produce 5½ twists is a realistic possibility. To accomplish this limiting dive the diver needs to be able to coordinate the timing of configurational changes with the progress of the twist with a precision of 10 ms or better.

The limits of aerial techniques for producing twist in forward 1½ somersault dives

An angle-driven computer simulation model of aerial movement was used to determine the maximum amount of twist that can be produced in a forward 1½ somersault dive from a three-metre springboard using various aerial twisting techniques. The segmental inertia parameters of an elite springboard diver were used in the simulations and lower bounds were placed on the durations of arm and hip angle changes based on recorded performances of twisting somersaults. A limiting dive was identified as that producing the largest possible whole number of twists. Simulations of the limiting dives were found using simulated annealing optimisation to produce the required amounts of somersault, tilt and twist after a flight time of 1.5 s. Additional optimisations were then run to seek solutions with the arms less adducted during the twisting phase. It was found that the upper limits ranged from two to five twists with arm abduction ranges lying between 6° and 17°. Similar results were obtained when the inertia parameters of two other springboard divers were used.

Twist limits for late twisting double somersaults on trampoline

An angle-driven computer simulation model of aerial movement was used to determine the maximum amount of twist that could be produced in the second somersault of a double somersault on trampoline using asymmetrical movements of the arms and hips. Lower bounds were placed on the durations of arm and hip angle changes based on performances of a world trampoline champion whose inertia parameters were used in the simulations. The limiting movements were identified as the largest possible odd number of half twists for forward somersaulting takeoffs and even number of half twists for backward takeoffs. Simulations of these two limiting movements were found using simulated annealing optimisation to produce the required amounts of somersault, tilt and twist at landing after a flight time of 2.0s. Additional optimisations were then run to seek solutions with the arms less adducted during the twisting phase. It was found that 3½ twists could be produced in the second somersault of a forward piked double somersault with arms abducted 8° from full adduction during the twisting phase and that three twists could be produced in the second somersault of a backward straight double somersault with arms fully adducted to the body. These two movements are at the limits of performance for elite trampolinists.

Radiographic and clinical factors associated with one-leg standing and gait in patients with mild-to-moderate secondary hip osteoarthritis

A decline in physical function associated with secondary hip osteoarthritis (OA) may be caused by both radiographic and clinical factors; however, the underlying mechanism remains unclear. The purpose of this study was to determine how joint degeneration, hip morphology, pain, hip range of motion (ROM), and hip muscle strength relate to one-leg standing (OLS) and gait in patients with mild-to-moderate secondary hip osteoarthritis. Fifty-five female patients (ages 22–65 years) with mild-to-moderate hip OA secondary to hip dysplasia were consecutively enrolled. Balance during OLS and three-dimensional hip angle changes while maintaining the OLS and at foot-off of the raised leg were measured. Gait speed and peak three-dimensional hip joint angles during gait were also measured. The associations between dependent variables (balance, gait speed, and hip kinematic changes) and independent variables (age, body mass index, pain, joint degeneration, hip morphologic abnormality, passive hip ROM, and hip muscle strength) were determined. While lower hip muscle strength was associated with hip kinematic changes such as flexion and internal rotation while maintaining OLS, decreased acetabular head index (AHI) and increased pain were associated with hip extension and abduction at foot-off in OLS. Decreased passive hip ROM was associated with decreased peak hip angles (extension, adduction, and external and internal rotation) during gait, although increased pain and decreased hip extension muscle strength were associated with slower gait speed. In this study of patients with secondary hip OA, AHI, pain, and hip impairments were associated with OLS and gait independently from age and radiographic degeneration.

No evidence hip joint angle modulates intrinsically produced stretch reflex in human hopping

Motor output in activities such as walking and hopping is suggested to be mediated neurally by purported stretch reflex augmentation of muscle output. Reflex EMG activity during these tasks has been frequently investigated in the soleus muscle; with alterations in reflex amplitude being associated with changes in hip joint angle/phase of the gait cycle. Previous work has focussed on reflex activity induced by an artificial perturbation or by induction of H-reflexes. As such, it is currently unknown if stretch reflex activity induced intrinsically (as part of the task) is modulated by changes in hip joint angle. This study investigated whether hip joint angle modulated reflex EMG ‘burst’ activity during a hopping task performed on a custom-built partially reclined sleigh. Ten subjects participated; EMG and kinematic data (VICON motor capture system) was collected for each hop cycle. Participants completed 5 sets of 30s of self-paced hopping in (1) hip neutral and (2) hip 60° flexion conditions. There was no difference in EMG ‘burst’ activity or in sagittal plane kinematics (knee/ankle) in the hopping task between the two conditions. The results indicate that during a functional task such as hopping, changes in hip angle do not alter the stretch reflex-like activity associated with landing.

A QUASI-LINEAR VISCOELASTIC MODEL FOR THE PASSIVE PROPERTIES OF THE HUMAN HIP JOINT

Properties of passive elastic structures constituting the human hip joint can be exploited to increase efficiency of human locomotion. As studies estimating the passive contributions to the net joint moment often disregard damping properties of the joint such contributions overestimate the energy gained during leg retraction within swing and stance phase. We built an experimental apparatus to measure moment-angle-relations during motor guided cyclic movements over a wide range of angular velocities and step-like changes in hip angle. On the basis of the experimentally gained data set the objective of this study was to model the elastic as well as the damping characteristics of the joint in the sagittal plane utilizing the Quasi-Linear Viscoelastic theory (QLV). A double exponential function was conveniently employed to describe the elastic response. The dependency of the hip joint stiffness on biarticular muscles was incorporated by repeating the measurement protocol for different knee angles. Due to the fact that the stiffness characteristics of the elastic response were merely shifted over knee angles we introduced an equilibrium angle at the hip joint as exponential function of the knee angle eventually yielding an elastic response as a function of hip and knee angle. In order to cover the damping characteristics the reduced relaxation function comprising a continuous spectrum of relaxation was utilized. We exemplify the applicability of the QLV model on published kinematic data on human walking and estimated that approximately 27% of the energy passively stored at the hip dissipates during the gait cycle.

Identification of Static and Dynamic Properties Induced by Hip Changes to Flexion Withdrawal Reflex in Chronic Human Spinal Cord Injury

The aim of this study was to investigate the static and dynamic properties of the flexion withdrawal reflex modulated by hip changes in human spinal cord injury. The influence of the hip position and passive movement were tested in six subjects with chronic spinal cord injury. Each subject was placed in a supine position and lower limb was fixed with the knee at 23.7±16.0 degrees flexion and the ankle at 33.3±5.2 degrees plantar flexion. A train of 10 stimulus pulses were applied at 200Hz to the skin of the medial arch to elicit the nociceptive flexion reflexes. From results of the regression analysis, activation of flexor muscles (tibialis anterior and illiopsoas) during static hip angle changes has a linear relationship with respect to hip angle (P<0.05). As the hip flexion angle increases, the EMG activity decreases. A significant linear relationship was also found between the reflex activity of flexor muscle (illiopsoas) and hip angular velocity during both hip flexion and hip extension movement (P<0.05). In order to validate the reflex response, we compared the static and dynamic gains of estimated activation with measured electromyogram of tibialis anterior. From this study, we postulate that flexor muscle activities of nociceptive flexion reflex have linear relationship with hip angle and angular velocity.

Excitation of Knee Extensor Muscles During Maximal Isometric Contraction at Different Hip and Knee Angles

The quadriceps consists of monoarticular and biarticular muscles. Since changes in hip angle only influence the length of biarticular muscles, it can be expected that monoarticular muscle excitation is not influenced by hip angles. PURPOSE: To compare excitation of the monoarticular (vastus lateralis VL and vastus medialis VM) and biarticular (rectus femoris RF) knee extensor muscles during maximal isometric contraction at different hip and knee angles. METHODS: Nine subjects (4 male; 5 female; mean ± SD: age 23 ± 2.29 yrs, mass 64.2 ± 11.7 kg, height 1.69 ± 0.10 m) gave informed consent to participate in this study. Each subject performed a 3-s maximal isometric knee extension at 6 knee angles (90°, 100°, 110°, 120°, 130° and 140°, full knee extension = 180°) on an isovelocity dynamometer with a 1-min rest period between trials. The test was repeated at three hip positions: sitting (H1), inclined (H2) and lying (H3). Hip angles were measured using a goniometer during isometric contractions. Torque data were corrected for gravity effects and normalized to the peak value recorded in H1 (any knee angle). A surface electromyography (EMG) system was used to measure muscle excitation of the RF, VL and VM. Raw EMG data were full-wave rectified and then root mean squared (RMS) with a 0.5-s window. The highest RMS value averaged over a 1-s window was used for analysis. All EMG data were normalized to the RMS value at 90° knee angle in H1. Repeated measures ANOVA (hip × knee) was used to determine the effect of hip and knee angles on peak isometric torque and muscle excitation. RESULTS: The three hip angles were 109.6 ± 3.16° (H1), 138.6 ± 3.5° (H2) and 163.6 ± 3.28° (H3). Peak torques were higher in H2 than in H1 and H3 (P = 0.044). A quadratic torque-angle relationship was observed as knee angle changed (P < 0.0005) at all hip angles. Hip angle influenced VL excitation (P = 0.029, H1 > H2 > H3) but not RF or VM excitation. All knee extensor EMG decreased as knee angle increased (RF: P < 0.0005, VL: P = 0.001, VM: P = 0.002) and there were no differences in the pattern of response at different hip angles. CONCLUSION: Knee extensor EMG-angle relationship does not correspond well with the torque-angle relationship. The fact that changes in hip angle do not affect biarticular but monoarticular muscles excitation urges further research on neuromuscular control mechanism.

Stretch reflex modulation during imposed static and dynamic hip movements in standing humans

The purpose of this study was to investigate the effects of hip proprioceptors on soleus stretch reflex excitability in standing humans. A custom-made device to stretch the ankle extensors was mounted on the lower leg portion of a gait orthosis and was used to elicit stretch reflex responses while standing. Six subjects with motor complete spinal cord injury (SCI) and six spinal intact subjects were placed in the orthosis, and stretch reflex responses were elicited when static and/or dynamic hip joint angle changes were imposed. We found that static hip extension significantly enhanced the stretch reflex responses as compared to the neutral position and the hip flexion position only in the SCI group. The EMG magnitude induced by hip extension was 142 +/- 16.6% greater than that induced by the neutral position. When the leg was dynamically swung, the reflex responses also changed with the phase of the hip angle in the SCI group; in particular, the reflex amplitude was enhanced with hip extension and in the transition phase from flexion to extension. Although the magnitude of the changes was less than that in the SCI group, a similar type of modulation was found in the normal group. Given the fact that the persons with SCI had lost the neural connection between higher nervous center and the paralyzed lower limb muscles, the mechanism underlying the present results can be attributed to the peripheral afferent input due to the hip angle changes. We concluded that hip mediated afferent input has a significant influence on the excitability modulation of the soleus stretch reflex pathway. Such neural modulation may play a role in the mechanism responsible for the phase-dependent modulation of the stretch reflex while walking.

EFFECTS OF CHANGES IN HIP POSITION ON ACTIONS OF SPINAL INHIBITORY INTERNEURONS IN HUMANS

The aim of the present study was to establish whether in healthy human subjects the actions of group I muscle afferents arising from the same spinal segments as the soleus innervation (e.g., common peroneal nerve; CPN) or from more proximal spinal segments (femoral nerve; FN) on the soleus H-reflex are modified by changes in hip position. Control and conditioned soleus H-reflexes were elicited and recorded via conventional methods. In seated subjects, CPN and FN stimulation resulted in similar effects to the soleus H-reflex to that previously reported in healthy subjects. However, during hip angle changes, CPN stimulation at the C-T interval of 2 ms resulted in soleus H-reflex depression only when the hip was flexed at 30°, whereas with the hip flexed or extended at 10° the H-reflex was facilitated. CPN stimulation delivered at 100 ms also induced soleus H-reflex facilitation regardless of the hip angle tested. The heteronymous reflex facilitation (conditioned H-reflex with FN stimulation) did not vary systematically with hip angle changes. These findings indicate that hip proprioceptors interact with spinal inhibitory interneurons to enhance spinal reflex excitability under static conditions. This neural switch might constitute an important feature of movement regulation in humans.

MODULATION OF THE SOLEUS H-REFLEX DURING STATIC AND DYNAMIC IMPOSED HIP ANGLE CHANGES

The aim of the study was to investigate the modulation of the soleus H-reflex during static and dynamic imposed hip angle changes. Five healthy subjects participated. H-reflexes were measured during hip joint passively flexed and extended in the sagittal plane. In flexion phase, the soleus H-reflex during dynamic conditions was lower than the stationary controls. By contrast, it was conversely higher in extension phase. The findings suggest that the modulation of the soleus H-reflex from hip proprioceptors is a major factor in passive hip movement. Additionally, the central pattern generator might modulate the soleus H-reflex.

Modulation of flexion reflex induced by hip angle changes in human spinal cord injury.

The flexion reflex can be elicited via stimulation of skin, muscle, and high-threshold afferents inducing a generalized flexion of the limb. In spinalized animal models this reflex is quite prominent and is strongly modulated by actions of hip proprioceptors. However, analogous actions on the flexion reflex in spinal cord injured (SCI) humans have not yet been examined. In this study, we investigated the effects of imposed static hip angle changes on the flexion reflex in ten motor incomplete SCI subjects when input from plantar cutaneous mechanoreceptors was also present. Flexion reflexes were elicited by low-intensity stimulation of the sural nerve at the lateral malleolus, and were recorded from the ipsilateral tibialis anterior (TA) muscle. Plantar skin stimulation was delivered through two surface electrodes placed on the metatarsals, and was initiated at different delays ranging from 3 to 90 ms. We found that non-noxious sural nerve stimulation induced two types of flexion reflexes in the TA muscle, an early, and a late response. The first was observed only in three subjects and even in these subjects, it appeared irregularly. In contrast, the second (late) flexion reflex was present uniformly in all ten subjects and was significantly modulated during hip angle changes. Flexion reflexes recorded with hip positioned at different angles were compared to the associated control reflexes recorded with hip flexed at 10 degrees. Hip flexion (30 degrees, 40 degrees) depressed the late flexion reflex, while no significant effects were observed with the hip set in neutral angle (0 degrees). Strong facilitatory effects on the late flexion reflex were observed with the hip extended to 10 degrees. Moreover, the effects of plantar skin stimulation on the flexion reflex were also found to depend on the hip angle. The results suggest that hip proprioceptors and plantar cutaneous mechanoreceptors strongly modulate flexion reflex pathways in chronic human SCI, verifying that this type of sensory afferent feedback interact with spinal interneuronal circuits that have been considered as forerunners of stepping and locomotion. The sensory consequences of this afferent input should be considered in rehabilitation programs aimed to restore movement and sensorimotor function in these patients.

Gender differences in the location of the center of buoyancy of competitive swimmers

An angle-driven computer simulation model of aerial movement was used to determine the maximum amount of twist that could be produced in the second somersault of a double somersault on trampoline using asymmetrical movements of the arms and hips. Lower bounds were placed on the durations of arm and hip angle changes based on performances of a world trampoline champion whose inertia parameters were used in the simulations. The limiting movements were identified as the largest possible odd number of half twists for forward somersaulting takeoffs and even number of half twists for backward takeoffs. Simulations of these two limiting movements were found using simulated annealing optimisation to produce the required amounts of somersault, tilt and twist at landing after a flight time of 2.0 s. Additional optimisations were then run to seek solutions with the arms less adducted during the twisting phase. It was found that 3½ twists could be produced in the second somersault of a forward piked double somersault with arms abducted 8° from full adduction during the twisting phase and that three twists could be produced in the second somersault of a backward straight double somersault with arms fully adducted to the body. These two movements are at the limits of performance for elite trampolinists.

The crowhop: Technique fault or unfair advantage?

An angle-driven computer simulation model of aerial movement was used to determine the maximum amount of twist that could be produced in the second somersault of a double somersault on trampoline using asymmetrical movements of the arms and hips. Lower bounds were placed on the durations of arm and hip angle changes based on performances of a world trampoline champion whose inertia parameters were used in the simulations. The limiting movements were identified as the largest possible odd number of half twists for forward somersaulting takeoffs and even number of half twists for backward takeoffs. Simulations of these two limiting movements were found using simulated annealing optimisation to produce the required amounts of somersault, tilt and twist at landing after a flight time of 2.0 s. Additional optimisations were then run to seek solutions with the arms less adducted during the twisting phase. It was found that 3½ twists could be produced in the second somersault of a forward piked double somersault with arms abducted 8° from full adduction during the twisting phase and that three twists could be produced in the second somersault of a backward straight double somersault with arms fully adducted to the body. These two movements are at the limits of performance for elite trampolinists.