Comprehensive linear and nonlinear analysis of the effects of spinning on dynamic balancing ability in Hungarian folk dancers.

PURPOSE: In the case of Hungarian folk dancers, it is crucial to maintain correct posture and promptly respond to imbalances. However, traditional dances often lack specific training to develop these skills. METHODS: In this present study, twelve dancers (8 male, 4 female, age: 21.7 ± 3.6 years) and ten non-dancers subjects forming a control group (6 male, 4 female, age: 21.6 ± 2.87 years) participated. During the measurements a 60-second long bipedal balancing test on the balance board was completed two times, and a spinning intervention was inserted in between the two sessions. The balance capabilities of the two groups were assessed through the characterization of motion on an unstable board, and the analysis of subject's center of mass and head movements. RESULTS: Dancers applied a more sophisticated and resource-intensive strategy to address the balancing task, yielding a better balancing performance in terms of balance board parameters. By preferring a solid stability in the medio-lateral direction, a greater fluctuation in the anterior-posterior direction can be observed (e.g., significantly lower SampEn values). The overall more successful performance is further evidenced by within-subject comparison since significant differences were observed mostly within the control group. Based on the results, the advanced balancing ability of the folk dancer group is more likely to be acquired through years of experience. CONCLUSION: The results indicate that additional specialized training could further enhance this ability, encouraging the reliance on poorly memorized corrective movements and reducing the risk of injury.

Compensatory muscle activation and spinal curve changes in response to fatigue among adolescent male athletes.

BACKGROUND: The prone plank test has been often used to assess the strength and endurance of trunk muscles. We aimed to develop a new measurement protocol to objectively monitor the changes in spinal curves and muscle activity simultaneously. METHODS: Eleven adolescent male basketball athletes (13-17 years) performed a one-minute plank test. Spinal curvatures (thoracic kyphosis (TK) and lumbar lordosis (LL)) were determined at each time point by optical tracking of markers placed on the spinous processes of 10 vertebrae. Eleven muscles were measured by surface electromyography to determine muscle fatigue via changes in median frequency. RESULTS: TK significantly increased (p = 0.003) from the first to the last 10 s of the plank test; changes in LL were mixed within the group. Only the rectus abdominis showed consistent and significant fatigue (p < 0.001). The increased spinal curves significantly correlated with the fatigue of biceps femoris (TK: r = -0.75, p = 0.012; LL: r = -0.71, p = 0.019) indicating a compensatory muscle activation and spinal curve changes in response to fatigue. CONCLUSION: Our protocol may support future researches that aim to objectively evaluate the prone plank test and which posture-related muscles need strengthening for the individual.

Biosignal processing methods to explore the effects of side-dominance on patterns of bi- and unilateral standing stability in healthy young adults.

We examined the effects of side-dominance on the laterality of standing stability using ground reaction force, motion capture (MoCap), and EMG data in healthy young adults. We recruited participants with strong right (n = 15) and left (n = 9) hand and leg dominance (side-dominance). They stood on one or two legs on a pair of synchronized force platforms for 50 s with 60 s rest between three randomized stance trials. In addition to 23 CoP-related variables, we also computed six MoCap variables representing each lower-limb joint motion time series. Moreover, 39 time- and frequency-domain features of EMG data from five muscles in three muscle groups were analyzed. Data from the multitude of biosignals converged and revealed concordant patterns: no differences occurred between left- and right-side dominant participants in kinetic, kinematic, or EMG outcomes during bipedal stance. Regarding single leg stance, larger knee but lower ankle joint kinematic values appeared in left vs right-sided participants during non-dominant stance. Left-vs right-sided participants also had lower medial gastrocnemius EMG activation during non-dominant stance. While right-side dominant participants always produced larger values for kinematic data of ankle joint and medial gastrocnemius EMG activation during non-dominant vs dominant unilateral stance, this pattern was the opposite for left-sided participants, showing larger values when standing on their dominant vs non-dominant leg, i.e., participants had a more stable balance when standing on their right leg. Our results suggest that side-dominance affects biomechanical and neuromuscular control strategies during unilateral standing.

Handedness did not affect motor skill acquisition by the dominant hand or interlimb transfer to the non-dominant hand regardless of task complexity level.

Patients undergoing unilateral orthopedic or neurological rehabilitation have different levels of impairments in the right- or left-dominant hand. However, how handedness and the complexity of the motor task affect motor skill acquisition and its interlimb transfer remains unknown. In the present study, participants performed finger key presses on a numeric keypad at 4 levels of sequence complexities with each hand in a randomized order. Furthermore, they also performed motor sequence practice with the dominant hand to determine its effect on accuracy, reaction time, and movement time. The NASA-TLX at the end of each block of both testing and practice was used to confirm participants' mental workload related to sequence complexity. Both right- and left-handed participants performed the motor sequence task with faster RT when using their right hand. Although participants had increasing RT with increasing sequence complexity, this association was unrelated to handedness. Motor sequence practice produced motor skill acquisition and interlimb transfer indicated by a decreased RT, however, these changes were independent of handedness. Higher sequence complexity was still associated with longer RT after the practice, moreover, both right- and left-handed participants' RT increased with the same magnitude with the increase in sequence complexity. Similar behavioral pattern was observed in MT as in RT. Overall, our RT results may indicate left-hemisphere specialization for motor sequencing tasks, however, neuroimaging studies are needed to support these findings. On the other hand, handedness did not affect motor skill acquisition by the dominant hand or interlimb transfer to the non-dominant hand regardless of task complexity level.

Development of a detailed canine gait analysis method for evaluating harnesses: A pilot study.

Dog harnesses are becoming more popular, with their large variety stemming from the idea that different dogs and scenarios require different types of harnesses. While their benefits over collars are self-explanatory, there is a lack of research on their effect on gait, and even the existing studies examine only a limited set of parameters. The goal of present study was to establish a method capable of quantifying canine gait in detail. Based on 3D motion capture, the developed method allows for the examination of 18 joint angles and 35 spatio-temporal parameters throughout multiple gait cycles, and can be used to analyze canine movement in detail in any kind of scenario (e.g. comparing healthy and lame dogs, or measuring the effect of training). The method is presented through the measurement of how different harnesses affect walking kinematics compared to free (unleashed) movements. Four dogs with varying body sizes and breeds and multiple types of harnesses were included. Marker data was filtered using a zero-lag 6th order Butterworth-filter with a cutoff frequency of 20 Hz. The normality of the spatio-temporal and joint range of motion parameters was tested using the Anderson-Darling test (p = 0.05), with most parameters passing in 60+% of test cases. Swing time and range of motion of the sagittal aspect of spinal angle at T1 vertebrae failed more regularly, both resulting from the measurement setup rather than the actual parameters being not normally distributed. Two-sample Kolmogorov-Smirnov tests (p = 0.05) were used to compare each parameter's distribution between cases, showing that most parameters are significantly altered by the harnesses in about 2/3rd of the cases. Based on the results, there's no absolute superior harness, however, it is possible to select the best fit for a specific dog and application, justifying their large variety.

Selection and Optimization of Temporal Spike Encoding Methods for Spiking Neural Networks.

Spiking neural networks (SNNs) receive trains of spiking events as inputs. In order to design efficient SNN systems, real-valued signals must be optimally encoded into spike trains so that the task-relevant information is retained. This paper provides a systematic quantitative and qualitative analysis and guidelines for optimal temporal encoding. It proposes a methodology of a three-step encoding workflow: method selection by signal characteristics, parameter optimization by error metrics between original and reconstructed signals, and validation by comparison of the original signal and the encoded spike train. Four encoding methods are analyzed: one stimulus estimation [Ben's Spiker algorithm (BSA)] and three temporal contrast [threshold-based, step-forward (SW), and moving-window (MW)] encodings. A short theoretical analysis is provided, and the extended quantitative analysis is carried out applying four types of test signals: step-wise signal, smooth (sinusoid) signal with added noise, trended smooth signal, and event-like smooth signal. Various time-domain and frequency spectrum properties are explored, and a comparison is provided. BSA, the only method providing unipolar spikes, was shown to be ineffective for step-wise signals, but it can follow smoothly changing signals if filter coefficients are scaled appropriately. Producing bipolar (positive and negative) spike trains, SW encoding was most effective for all types of signals as it proved to be robust and easy to optimize. Signal-to-noise ratio (SNR) can be recommended as the error metric for parameter optimization. Currently, only a visual check is available for final validation.

Affordable gait analysis using augmented reality markers.

A typical optical based gait analysis laboratory uses expensive stereophotogrammetric motion capture systems. The study aims to propose and validate an affordable gait analysis method using augmented reality (AR) markers with a single action camera. Image processing software calculates the position and orientation of the AR markers. Anatomical landmark calibration is applied on the subject to calibrate each of the anatomical points with respect to their corresponding AR markers. This way, anatomical points are tracked through AR markers using homogeneous coordinate transformations, and the further processing of gait analysis is identical with conventional solutions. The proposed system was validated on nine participants of varying age using a conventional motion capture system on simultaneously measured treadmill gait trials on 2, 3 and 4.5 km/h walking speeds. Coordinates of the virtual anatomical points were compared using the Bland-Altman analysis. Spatial-temporal gait parameters (step length, stride length, walking base, cadence, pelvis range of motion) and angular gait parameters (range of motion of knee, hip and pelvis angles) were compared between measurement systems by RMS error and Bland-Altman analysis. The proposed method shows some differences in the raw coordinates of virtually tracked anatomical landmarks and gait parameters compared to the reference system. RMS errors of spatial parameters were below 23 mm, while the angular range of motion RMS errors varies from 2.55° to 6.73°. Some of these differences (e.g. knee angle range of motion) is comparable to previously reported differences between commercial motion capture systems and gait variability. The proposed method can be a very cheap gait analysis solution, but precision is not guaranteed for every aspect of gait analysis using the currently exemplified implementation of the AR marker tracking approach.

Effectiveness and recovery action of a perturbation balance test - a comparison of single-leg and bipedal stances.

Dynamic balancing abilities can be assessed with perturbation tests. The present study examined the effectiveness of balancing (damping ratio) and the recovery action (directional ratio) in bipedal and dominant single-leg stance in the young population. Twenty-four healthy young adult participants completed unidirectional lateral perturbations successfully using a Posturomed© platform (Haider Bioswing, Germany). Single-leg stances had similar damping scores (p = 0.551) to and lower directional ratio values (p = 0.002) than bipedal recoveries. This shows that different recovery actions can achieve similar effectiveness in the two stances. A test evaluation methodology that simultaneously utilises performance and motion characteristic parameters was demonstrated.

Comparison of spinal curvature parameters as determined by the ZEBRIS spine examination method and the Cobb method in children with scoliosis.

BACKGROUND AND PURPOSE: The most common and gold standard method to diagnose and follow-up on scoliosis treatment is to capture biplanar X-ray images and then use these to determine the sagittal frontal spinal curvature angles by the Cobb method. Reducing exposure to radiation is an important aspect for consideration, especially regarding children. The ZEBRIS spinal examination method is an external, non-invasive measurement method that uses an ultrasound-based motion analysis system. The aim of this study is to compare angle values of patients with adolescent idiopathic scoliosis (AIS) determined by the ZEBRIS spine examination method with the angle values defined by the gold standard Cobb method on biplanar X-ray images. METHODS: Subjects included 19 children with AIS (mean age 14.5±2.1 years, range 8-16 years, frontal plane thoracic Cobb angle 19.95±10.23°, thoracolumbar/lumbar angle 16.57±10.23°). The thoracic kyphosis and lumbar lordosis in the sagittal plane and the thoracic and lumbar scoliosis values were calculated by the Cobb method on biplanar X-ray images. The sagittal frontal spinal curvature angles were calculated from the position of the processus spinosus of 19 vertebrae, as determined by the ZEBRIS spine examination method. The validity of the ZEBRIS spine examination method was evaluated with Bland-Altman analyses between the sagittal and frontal spinal curvature parameters calculated from data determined by the ZEBRIS spine examination method and data obtained by the Cobb method on the X-ray images. RESULTS AND DISCUSSION: Thoracic spinal curvature angles in sagittal and in frontal planes can be measured with sufficient accuracy. The slopes of the linear regression lines for thoracic kyphosis (TK) and thoracic scoliosis (TSC) are close to one (1.00 and 0.79 respectively), and the intercept values are below 5 degrees. The correlation between the TK and TSC values determined by the two methods is significant (p = 0.000) and excellent (rTK = 0.95, rTSC = 0.85). The differences are in the limit of agreement. The lumbar lordosis (LL) in the sagittal plane shows a very good correlation (rLL = 0.76); however the differences between the angles determined by the two methods are out of the limit of agreement in patients with major lumbar lordosis (LL≥50°). The thoracolumbar/lumbar spinal curvature angles in the frontal plane determined by ZEBRIS spine examination were underestimated at curvatures larger than 15°, mainly due to the rotational and pathological deformities of the scoliotic vertebrae. However, the correlation between lumbar scoliosis (LSC) values determined by the two methods is significant (p = 0.000) and excellent (rLSC = 0.84), the slopes are below one (0.71), the intercept values are below 5 degrees, and the differences between the angles determined by the two methods are within the limits of agreement. We could conclude that ZEBRIS spinal examination is a valid and reliable method for determination of sagittal and frontal curvatures during the treatment of patients with scoliosis. However, it cannot replace the biplanar X-ray examination for the visualization of spinal curvatures in the sagittal and frontal planes and the rotation of vertebral bodies during the diagnosis and annual evaluation of the progression.

Reliability analysis of a sensitive and independent stabilometry parameter set.

Recent studies have suggested reduced independent and sensitive parameter sets for stabilometry measurements based on correlation and variance analyses. However, the reliability of these recommended parameter sets has not been studied in the literature or not in every stance type used in stabilometry assessments, for example, single leg stances. The goal of this study is to evaluate the test-retest reliability of different time-based and frequency-based parameters that are calculated from the center of pressure (CoP) during bipedal and single leg stance for 30- and 60-second measurement intervals. Thirty healthy subjects performed repeated standing trials in a bipedal stance with eyes open and eyes closed conditions and in a single leg stance with eyes open for 60 seconds. A force distribution measuring plate was used to record the CoP. The reliability of the CoP parameters was characterized by using the intraclass correlation coefficient (ICC), standard error of measurement (SEM), minimal detectable change (MDC), coefficient of variation (CV) and CV compliance rate (CVCR). Based on the ICC, SEM and MDC results, many parameters yielded fair to good reliability values, while the CoP path length yielded the highest reliability (smallest ICC > 0.67 (0.54-0.79), largest SEM% = 19.2%). Usually, frequency type parameters and extreme value parameters yielded poor reliability values. There were differences in the reliability of the maximum CoP velocity (better with 30 seconds) and mean power frequency (better with 60 seconds) parameters between the different sampling intervals.

A novel validation and calibration method for motion capture systems based on micro-triangulation.

Motion capture systems are widely used to measure human kinematics. Nevertheless, users must consider system errors when evaluating their results. Most validation techniques for these systems are based on relative distance and displacement measurements. In contrast, our study aimed to analyse the absolute volume accuracy of optical motion capture systems by means of engineering surveying reference measurement of the marker coordinates (uncertainty: 0.75 mm). The method is exemplified on an 18 camera OptiTrack Flex13 motion capture system. The absolute accuracy was defined by the root mean square error (RMSE) between the coordinates measured by the camera system and by engineering surveying (micro-triangulation). The original RMSE of 1.82 mm due to scaling error was managed to be reduced to 0.77 mm while the correlation of errors to their distance from the origin reduced from 0.855 to 0.209. A simply feasible but less accurate absolute accuracy compensation method using tape measure on large distances was also tested, which resulted in similar scaling compensation compared to the surveying method or direct wand size compensation by a high precision 3D scanner. The presented validation methods can be less precise in some respects as compared to previous techniques, but they address an error type, which has not been and cannot be studied with the previous validation methods.

Devices and tasks involved in the objective assessment of standing dynamic balancing - A systematic literature review.

BACKGROUND: Static balancing assessment is often complemented with dynamic balancing tasks. Numerous dynamic balancing assessment methods have been developed in recent decades with their corresponding balancing devices and tasks. OBJECTIVE: The aim of this systematic literature review is to identify and categorize existing objective methods of standing dynamic balancing ability assessment with an emphasis on the balancing devices and tasks being used. DATA SOURCES: Three major scientific literature databases (Science Direct, Web of Science, PLoS ONE) and additional sources were used. STUDY SELECTION: Studies had to use a dynamic balancing device and a task described in detail. Evaluation had to be based on objectively measureable parameters. Functional tests without instrumentation evaluated exclusively by a clinician were excluded. A total of 63 articles were included. DATA EXTRACTION: The data extracted during full-text assessment were: author and date; the balancing device with the balancing task and the measured parameters; the health conditions, size, age and sex of participant groups; and follow-up measurements. DATA SYNTHESIS: A variety of dynamic balancing assessment devices were identified and categorized as 1) Solid ground, 2) Balance board, 3) Rotating platform, 4) Horizontal translational platform, 5) Treadmill, 6) Computerized Dynamic Posturography, and 7) Other devices. The group discrimination ability of the methods was explored and the conclusions of the studies were briefly summarized. LIMITATIONS: Due to the wide scope of this search, it provides an overview of balancing devices and do not represent the state-of-the-art of any single method. CONCLUSIONS: The identified dynamic balancing assessment methods are offered as a catalogue of candidate methods to complement static assessments used in studies involving postural control.

The effect of knee arthroplasty on balancing ability in response to sudden unidirectional perturbation in the early postoperative period.

INTRODUCTION AND OBJECTIVE: Total knee arthroplasty (TKA) affects 1-3% of the entire population. The effectiveness of surgery and rehabilitation are of great significance. The goal of this study was to determine how different surgical methods (i.e., conventional and minimally invasive) influence balancing ability in response to sudden unidirectional perturbation during the first 12 weeks of the postoperative period. MATERIALS AND METHODS: The balancing capacity after sudden unidirectional (horizontal) perturbation of 10 patients who had undergone TKA operations via the conventional method and 10 patients who had undergone TKA operations via the minimally invasive method were examined before and six and 12 weeks after TKA. Forty-five health age-matched participants composed the control group. The balancing capacities following unidirectional perturbation were characterised by the Lehr's damping ratio, which was calculated based on the results of the provocation tests that were performed with the patients standing on both the affected and non-affected limbs. RESULTS: In both patient groups, the Lehr's damping ratios increased during the postoperative period. However, in both patient groups, the Lehr's damping ratios calculated from the results of all three of the testing methods decreased compared to values obtained from the controls even at 12 weeks postoperatively. Six and 12 weeks after TKA, the Lehr's damping ratios of the patients who underwent operations utilising the minimally invasive exposure method were significantly higher than the values obtained from the patients who underwent operations by conventional exposure. DISCUSSION AND CONCLUSIONS: In both patient groups, the balancing capacities continuously improved over the first 12 weeks of the postoperative period, but the dynamic balancing capacities while standing on both limbs, on the affected limb and on the non-affected limb significantly differed from those of the controls. The balancing capacities of the patients who underwent the minimally invasive exposure procedures improved more rapidly than did the capacities of the patients who underwent operations utilising the conventional exposure method. This reduced balancing capacity should be considered when developing dynamic balancing abilities and abandoning therapeutic aids, and the difference in dynamic balancing abilities between the two patient groups should also be considered.

The assessment of the spinal curvatures in the sagittal plane of children using an ultrasound-based motion analysing system.

In children's posture examinations the question often arises whether an X-ray examination is necessary or appropriate. On screening and in other cases when X-ray is contraindicated, alternative-non-invasive-examinations are available. To measure the shapes of the children's spines beside the Spinal Mouse also the Zebris ultrasound-based spine measuring instrument is accessible and nowadays commonly used. The main aim of the study is to determine the shape of the school-age children's spines in the sagittal plane with an alternative, non-invasive, radiation-free measuring method. From the results calculated from the values measured with the ultrasound-based motion analysing system-geared to age and height-the normal range of the values of kyphosis (TK), lordosis (LL) and inclination (TTI and LI) is determined. The subjects were children between the ages of 6 and 15 and between the heights of 120 and 180 cm (530 healthy, 394 with bad posture and 332 with flat feet). They were divided into groups according to their height with 5 cm long intervals. The age within the groups was irrelevant. So it is appropriate to give normal values according to height and not according to age. It was revealed that both in healthy children, in children with bad posture and in those with pes planus in the height groups, there was a significant difference between the values of males and females. On the basis of these results, normal values should be divided according to the gender. The measurement results also showed that in some of the height groups the pes planus and bad posture significantly affected the spinal curvatures.

Variability of gait in the early postoperative period of total knee arthroplasty with different surgical technique.

PURPOSE: The purpose of this study was to work out an objective and sensitive method for the early postoperative period following total knee arthroplasty (TKA) in which analysis of the gait parameters is possible and also to investigate the influence of different surgical approaches for TKA on the gait during stepping in the first three months of the postoperative period. METHODS: Three groups of patients: age-matched healthy elderly patients as a control group, patients operated upon by the conventional technique and finally by the minimally invasive technique combined with computer-assisted navigation. All three groups included ten patients. The motions of knee, shoulder and pelvis were measured by ZEBRIS ultrasound-based system preoperatively plus six and 12 weeks postoperatively. From the joint motion, the variability of cadence, and the variability of knee joint motion and that of pelvis and shoulder girdle was determined. RESULTS: Osteoarthritis (OA) of the knee joint and TKA using both operation techniques significantly influenced the variability of stepping parameters compared to the controls. In the early postoperative period a significant difference was detected between the two groups of the operated patients in all parameters. CONCLUSION: Our data prove that our method seems appropriate to provide objective measurement of the gait in the early postoperative period. The variability of motion of the patient groups approaches that of the healthy control group steadily, but does not reach them.

Impact of the method of exposure in total hip arthroplasty on the variability of gait in the first 6months of the postoperative period.

INTRODUCTION, OBJECTIVE: Gait analysis has provided important information about the variability of gait for patients prior to and after total hip arthroplasty (THA). The objective of this research was to clarify how the method of exposure in total hip arthroplasty affects the variability of gait. MATERIALS AND METHOD: Gait analysis was performed at 0.8m/s, 1.0m/s, and 1.2m/s on 25 patients with direct-lateral exposure (DL), 22 with antero-lateral exposure (AL) and 25 with posterior exposure (P) during total hip arthroplasty. The control group was represented by 45 healthy subjects of identical age. Gait analysis was performed pre-operatively and 3 and 6months after the surgery. Gait parameter variability was characterized by the coefficient of variance (CV) of spatial-temporal parameters and by the mean coefficient of variance (MeanCV) of angular parameters. RESULTS: The variability of gait tends to reach control values during the first 6months of the postoperative period in all three patient groups. Six months after THA, in patients operated with DL and AL exposure the variability of gait differs significantly from control values; however, in patients operated with P exposure, the variability of spatial-temporal and angular parameters - except the rotation of pelvis - was similar to that of controls. DISCUSSION, CONCLUSION: The type of surgical technique significantly influences the variability of gait. Difference in the variability of angular parameters predicts gait instability and increased risk of falling after THA without the joint capsule preserved. Joint capsule preservation ensures a recovery of gait variability. It should be taken into account when compiling rehabilitation protocols. Differences related to the method of exposure should be considered when abandoning therapeutic aids.

Impact of the method of exposure in total hip arthroplasty on balancing ability in response to sudden unidirectional perturbation in the first six months of the postoperative period.

INTRODUCTION AND OBJECTIVE: Total hip arthroplasty affects 3-5% of the elderly population. Therefore, the effectiveness of surgery and the ensuing rehabilitation is of great significance. This study investigated balancing ability in response to sudden unidirectional perturbation changes during the first 6months of the postoperative period with respect to different methods of joint exposure during the operation (antero-lateral, direct-lateral and posterior to preserve the joint capsule). Our hypothesis is that the results may provide a tool to improve the rehabilitation procedures. MATERIALS AND METHODS: The dynamic balancing ability of 25 patients with direct-lateral exposure, 22 with antero-lateral exposure and 25 with posterior exposure during a total hip arthroplasty was examined using ultrasound-based provocation tests prior to and at 6weeks, 12weeks and 6months after total hip arthroplasty. The control group was represented by 45 healthy subjects of identical age. The dynamic balancing ability after unidirectional perturbation was characterised by Lehr's damping ratio calculated from the results of tests performed with the patient standing on both limbs, standing on the affected limb and standing on the non-affected limb. RESULTS: In the case of direct-lateral and antero-lateral exposure, Lehr's damping ratio significantly decreased compared to the preoperative values at 6weeks postoperatively, but it increased steadily afterwards. Lehr's damping ratio while standing on the affected limb was significantly lower - even at 6months postoperatively - than that of the control group. In the case of posterior exposure, Lehr's damping ratio continuously increased in the postoperative period and corresponded to that of the control group at 6months after total hip arthroplasty. DISCUSSION AND CONCLUSION: For patients operated on using direct-lateral and antero-lateral exposure methods, the dynamic balancing ability continuously improved in the first 6months of the postoperative period, but the dynamic balancing ability of the affected limb differed from that of the control group. In the case of posterior exposure to preserve the joint capsule the dynamic balancing ability evaluated a more rapidly compared to the other two exposure methods. There was no significant difference in the balancing ability of the control group at 6months after total hip arthroplasty with posterior exposure. The increasing range of joint motion, muscle development, and the development of the dynamic balancing ability should be taken into account when compiling rehabilitation protocols. Differences related to the method of exposure should be considered when developing the dynamic balancing ability and abandoning therapeutic aids.

Comparison of gait parameters in patients following total hip arthroplasty with a direct-lateral or antero-lateral surgical approach.

Total hip arthroplasty is a surgical procedure that usually results in almost complete pain relief and early improvement in functional capacity. Previous analyses of the gait of total hip arthroplasty patients have ignored the effect of total hip arthroplasty on the motion of other joints in the operated and non-operated limbs and of the pelvis. We investigated the spatiotemporal, angular, and kinetic parameters of affected and non-affected limbs pre-operatively and after three, six, and twelve months in 40 patients who underwent total hip arthroplasty via a direct-lateral approach, 40 patients who underwent an antero-lateral approach, and 40 age-matched healthy controls. In both patient groups pre-operatively, significant differences were observed in the spatiotemporal, angular, and kinetic parameters comparing the affected and the non-affected side; affected hip motion decreased, which was compensated by increased knee and hip motion of the non-affected side as well as pelvis obliquity and flexion-extension compared to healthy controls. Twelve months after total hip arthroplasty, direct-lateral patients displayed limited hip motion and increased pelvis rotation, while all antero-lateral patients exhibited gait patterns that most resembled the control group. This investigation has therefore identified a better functional outcome following an antero-lateral approach to total hip arthroplasty.

Effect of degree of knee osteoarthritis on balancing capacity after sudden perturbation.

This study aimed to assess equilibrium ability after sudden perturbation in patients with moderate and severe unilateral knee osteoarthritis (OA), with regard to age, gender, and lateral dominance. Our clinical trial included 45 female and 45 male healthy elderly subjects, 24 female and 24 male patients with moderate OA (mOA), and 24 female and 24 male patients with severe OA (sOA). Subjects were divided in two age groups: 65-69 and 70-74years. Using an oscillatory platform, we conducted provocation tests and determined the Lehr's damping ratio (D), which represents balancing capacity after sudden perturbation. D values determined for standing on both legs were similar to those of healthy individuals on the dominant limb or for OA patients on the non-affected limb; they were significantly lower for healthy individuals on the non-dominant limb and OA patients on the affected limb. For healthy subjects and mOA patients, D was significantly decreased with age and influenced by gender. sOA patients presented lower D values than other groups under all conditions, which were not influenced by age or gender. Our results demonstrate that OA patients were less capable of responding to perturbations, possibly indicating that they have an increased risk of falling.