Differences at motor control strategies to provide dynamic balance in various tasks in diabetic polyneuropatic (DPN) patients due to losing the lower extremity somatosensory information were reported in the literature. It has been stated that dynamics of center of mass (CoM) is controlled by center of pressure (CoP) during human upright standing and active daily movements. Indeed analyzing kinematic trajectories of joints unveil motor control strategies stabilizing CoM. Nevertheless, we hypothesized that imbalance disorders/CoM destabilization observed at DPN patients due to lack of tactile information about the base of support cannot be explained only by looking at joint kinematics, rather functional foot usage is proposed to be an important counterpart at controlling CoM. In this study, we included 14 DPN patients, who are diagnosed through clinical examination and electroneuromyography, and age matched 14 healthy subjects (HS) to identify control strategies in functional reach test (FRT). After measuring participants’ foot arch index (FAI) by a custom-made archmeter, they were tested by using a force plate, motion analysis system, surface electromyography and pressure pad, all working in synchronous during FRT. We analyzed data to determine effect of structural and functional foot pathologies due to neuropathy on patient performance and postural control estimating FAI, reach length (FR), FR to height (H) ratio (FR/H; normalized FR with respect to height), displacement of CoM and CoP in anteroposterior direction only, moment arm (MA, defined as the difference between CoP and CoM at the end of FRT), ankle, knee and hip joint angles computed at the sagittal plane for both extremities. Kinematic metrics included initial and final joint angles, defined with respect to start and end of reaching respectively. Further difference in the final and initial joint angles was defined as Δ. FAI was founded significantly lower in DPN patients (DPN: 0.3404; HS: 0.3643, p= <0.05). The patients’ FR, FR/H and absolute MA and displacement of CoM were significantly shorter than the control group (p= <0.05). Displacement of CoP between the two groups were not significant. Further we observed that CoM was lacking CoP in DPN patients (mean MA: +0.88 cm), while leading CoP in HS (mean MA: −1.59 cm) at the end of FRT. All initial angles were similar in two groups, however in DPN patients final right and left hip flexion angle (p=0.016 and p=0.028 respectively) and left ankle plantar flexion angle (p=0.04) were smaller than HS significantly. DPN patients had significantly less (p=0.029) hip flexion (mean at right hip angle, Δ=25.0°) compared to HS (Δ=33.53°) and ankle plantar flexion (DPN mean at right ankle angle, Δ=6.42°, HS mean Δ=9.07°; p=0.05). The results suggest that movement of both hip and ankle joints was limited simultaneously in DPN patients causing lack of CoM with respect to CoP at the end of reaching with significantly lower FAI. These results lead to the fact that cutaneous and joint somatosensory information from foot and ankle along with the structure of foot arch may play an important role in maintaining dynamic balance and performance of environmental context. In further studies, we expect to show that difference at control strategies in DPN patients due to restricted functional foot usage might be a good predictor of how neuropathy evolves to change biomechanical aspects of biped erect posture

The aim of this research was to determine biomechanical markers which differentiate medial knee osteoarthritis (OA) patients who do and do not show structural progression over a 2-year period. A cohort of 36 subjects was selected from a longitudinal study (Meireles et al 2017) using Kellgren-Lawrence (KL) scores at baseline and 2-year follow-up. The cohort consisted of 10 healthy controls (HC) (KL=0 at both time points), 15 medial knee OA non-progressors (NPKOA) (KL≥1 at baseline and no change over 2 years), and 11 medial knee OA progressors (PKOA) (KL≥1 at baseline and increase of ≥1 over 2 years). 3D integrated motion capture data from three walking trials were processed through a musculoskeletal modelling framework (Smith et al 2016) to estimate knee joint loading parameters (i.e., magnitude of mean contact pressure, and centre of pressure (COP)). Parameters at first and second peak were extracted and compared between groups using Kruskal-Wallis and Mann-Whitney tests. Higher magnitudes were observed in PKOA vs NPKOA, and PKOA vs HC groups at both time points. Additionally, a posterior (1st and 2nd peak), and lateral (2nd peak) shift in medial compartment COP was shown between PKOA and NPKOA, and PKOA and HC subjects. Interestingly, in the studied parameters, no differences were observed between NPKOA and HC groups. Significantly higher magnitude, and a more posterior and lateral COP was observed between PKOA and NPKOA patients. These differences, combined with an absence of difference between NPKOA and HC suggest structural OA progression is driven by a combination of altered loading magnitude and location. These results may serve as guidelines for targeted gait retraining rehabilitation to slow or stop knee OA progression whereby shifting COP anterior and medial and reducing magnitude by ~22% may shift patients from a PKOA to a NPKOA trajectory

Medical and allied health staff are beginning to incorporate the Nintendo Wii-Fit into musculoskeletal rehabilitation protocols. One potential application is the assessment of standing balance following Orthopaedic lower limb surgery. The Wii Balance Board (WBB) has been shown to be a valid equivalent to a laboratory grade force platform for the assessment of standing balance. Our objective was to investigate the validity and reliability of the balance tests included with the Wii-Fit software. Initially, a single subject performed multiple repeats of a standing balance test. The data was collected simultaneously from a commercial force platform using its integrated software that measured centre of pressure and from the WBB using the Wii-Fit software that generated a percentage score. The data from each was compared and analyzed, applying the equations of known, validated standing balance measurements. Then, thirty subjects free of lower limb pathology performed a series of standing balance tests combining single leg and double leg stance with their eyes open and then closed. Data was collected from one set of trials on the WBB using the Wii-Fit software and another using bespoke centre of pressure software on a laptop computer. The tests were then repeated on a second occasion within 2 weeks. The algorithm used by the Wii-Fit software to generate the ‘Stillness’ standing balance score was calculated with a predictive value (R squared) of 0.94. This correlated well to a known, valid measure of standing balance. Test-retest reliability was examined for the data from both pieces of software. Both demonstrated good-to-excellent test-retest reliability within ‘software’. The laptop data was transformed using the algorithm and the between ‘software’ reliability was calculated as good-to-excellent. The Wii-Fit software collects standing balance data from the WBB at a fraction of the cost of laboratory grade systems. The score generated by the Wii-Fit software is reliable and valid as an overall assessment of standing balance. Although its application would be limited for detailed assessment of balance disorders, it could still provide surgeons with an affordable, clinic based balance-screening tool. This could form part of an assessment protocol following lower limb surgery

It has been recently being investigated how the pressure distribution beneath the foot points to the active usage of the foot in standing adults. Nevertheless, it offers new perspectives in postural research by introducing foot-triggered sensory-motor control strategies in quiet standing dynamics. Furthermore, the spatiotemporal evolution of physiological postural control strategies has not clearly been identified yet. Thus, we have chosen developmental aspects of the infant's postural adjustments as a media to explore learning of biped standing. This study investigates developmental changes in active usage of a contact surface and pressure distribution beneath infants’ foot during learning of upright posture. We started studying longitudinally on 22 female and 22 male infants at their 12.5. th. months (1. st. trimester, T1) and kept on screening the same subjects at every three months (19 females and 12 males at 15.5. th. months (T2), 17 females and 7 males at 18.4. th. months (T3)), during their normal checkup appointments in Gazi University Hospital, Social Pediatrics Department-Ankara/Turkey. Each trial was fulfilled by an infant standing on a pressure pad placed on top of a force plate to collect the pressure distribution data beneath the feet for 15 sec at T1, and 25-sec long duration at T2 and T3 and was repeated at least three times. During the data collection, infants’ parents were beside them trying to get infants’ attention towards themselves preventing them from being distracted and/or moving and walking around. The data collection setup additionally contained one camera for videotaping the infants’ reactions. Our main research interest in this study was to explore the spatiotemporal evolution of the behavioral characteristics of human postural sway. We expected to monitor the developmental changes at an infant's standing experience during their 2. nd. -year epoch through time-frequency domain analyses and explorative/exploitative informatics’ metrics. We computed Center of Pressure (CoP) time signal from the data collected by the force plate and the pressure pad. In time domain, mean and the variance at the CoP time signal were estimated in both antero-posterior (CoPx) and medio-lateral (CoPy) directions. In the frequency domain, 50% and 95% power frequency, centroidal frequency (CF), and frequency dispersion were calculated. We observed substantial developmental changes in every trimester, each being comparable with the previous one, which points to infants experiencing a major developmental milestone that can be noticed considerably even in the shorter time intervals. The phase plane analysis performed through the time signals and their time derivatives (estimated velocity of CoPx and CoPy) revealed a shrinkage in the characteristic pattern observed through the following epochs. One-Way ANOVA analysis demonstrated significant differences in 50% and 95% power and centroidal frequency of CoPx (p=0.001, p=0.000, p=0.000) and CoPy (p=0.002, p=0.000, p=0.000) respectively. Further, post hoc analyses demonstrated a significant difference at T1 compared against T2 and T3 for all three frequency domain metrics. Particularly speaking, CF dropped from 2.39 to 1.65 Hz, and from 2.86 to 1.70 Hz for CoPx and CoPy respectively, while passing from T1 to T2. The current status of this research managed to grasp the developmental aspects of infant standing through frequency domain metrics and reconstructed phase space analysis up to their 18 months old

In podiatric medicine, diagnosis of foot disorders is often merely based on tests of foot function in static conditions or on visual assessment of the patient's gait. There is a lack of tools for the analysis of foot type and for diagnosis of foot ailments. In fact, static footprints obtained via carbon paper imprint material have traditionally been used to determine the foot type or highlight foot regions presenting excessive plantar pressure, and the data currently available to podiatrists and orthotists on foot function during dynamic activities, such as walking or running, are scarce. The device presented in this paper aims to improve current foot diagnosis by providing an objective evaluation of foot function based on pedobarographic parameters recorded during walking. 23 healthy subjects (16 female, 7 males; age 35 ± 15 years; weight 65.3 ± 12.7; height 165 ± 7 cm) with different foot types volunteered in the study. Subjects' feet were visually inspected with a podoscope to assess the foot type. A tool, comprised of a 2304-sensor pressure plate (P-walk, BTS, Italy) and an ad-hoc software written in Matlab (The Mathworks, US), was used to estimate plantar foot morphology and functional parameters from plantar pressure data. Foot dimensions and arch-index, i.e. the ratio between midfoot and whole footprint area, were assessed against measurements obtained with a custom measurement rig and a laser-based foot scanner (iQube, Delcam, UK). The subjects were asked to walk along a 6m walkway instrumented with the pressure plate. In order to assess the tool capability to discriminate between the most typical walking patterns, each subject was asked to walk with the foot in forcibly pronated and supinated postures. Additionally, the pressure plate orientation was set to +15°, +30°, −15° and −30° with respect to the walkway main direction to assess the accuracy in measuring the foot progression angle (i.e. the angle between the foot axis and the direction of walk). At least 5 walking trials were recorded for each foot in each plate configuration and foot posture. The device allowed to estimate foot length with a maximum error of 5% and foot breadth with an error of 1%. As expected, the arch-index estimated by the device was the lowest in the cavus-feet group (0.12 ± 0.04) and the highest in the flat-feet group (0.29 ± 0.03). These values were between 4 – 10 % lower than the same measurements obtained with the foot scanner. The centre of pressure excursion index [1] was the lowest in the forcibly-pronated foot and the largest in the supinated foot. While the pressure plate used here has some limitations in terms of spatial resolution and sensor technology [2], the tool appears capable to provide information on foot morphology and foot function with satisfying accuracy. Patient's instrumental examination takes only few minutes and the data can be used by podiatrists to improve the diagnosis of foot ailments, and by orthotists to design or recommend the best orthotics to treat the foot condition

Financial and human cost effectiveness is an increasing evident outcome measure of surgical innovation. Considering the human element, the aim is to restore the individual to their “normal” state by sparing anatomy without compromising implant performance. Gait lab studies have shown differences between different implants at top walking speed, but none to our knowledge have analysed differing total hip replacement patients through the entire range of gait speed and incline to show differences. The purpose of this gait study was to 1) determine if a new short stem femoral implant would return patients back to normal 2) compare its performance to established hip resurfacing and long stem total hip replacement (THR) implants. 110 subjects were tested on an instrumented treadmill (Kistler Gaitway, Amherst, NY), 4 groups (short-stem THR, long-stem THR, hip resurfacing and healthy controls) of 28, 29, 27, and 26 respectively. The new short femoral stem patients (Furlong Evolution, JRI) were taken from the ongoing Evolution Hip trial that have been tested on the treadmill with minimum 12months postop. The long stem total hip replacements and hip resurfacing groups were identified from out 800 patient gait database. They were only chosen if they were 12 months postop and had no other joint disease or medical comorbidities which would affect gait performance. All subjects were tested through their entire range of gait speeds and incline after having a 5 minute habituation period. Speed intervals were at 0.5kms increments until maximum walking speed achieved and inclines at 4kms for 5, 10, 15%. At all incremental intervals of speed, the vertical component of the ground reaction forces, center of pressure and temporal measurements were collected for both limbs with a sampling frequency of 100Hz. Body weight scaling was applied to correct for mass differences and a symmetry index to compare the implanted hip to the contralateral normal hip. All variables for each subject group were compared to each other using an analysis of variance (ANOVA) with Tukey post hoc test with significance set at α=0.05. The four experimental groups were reasonably matched for demographics and the implant groups for PROMs. Hip resurfacing had a clear top walking speed advantage, but when assessing the symmetry index on all speeds and incline, all groups were not significantly different. Push-off and step length was statistically less favourable for the short/long THR group (p=0.005–0.05) depending on speed/incline. The primary aim of this study was determine if implant design affected gait symmetry and performance. Interestingly, irrespective of implant design, symmetry with regards to weight acceptance, impulse, push-off and step length was returned to normal when comparing to healthy controls. However individual implant performance on the flat and incline, showed inferior (p<0.05) push-off force and step length in the short stem and long stem THR groups when compared to controls. Age and gender may have played a part for the short stem group. It appears that the early gait outcomes for the short stem device are promising. Assessment at the 3 year mark should be conclusive

Malrotation of the femoral component is a cause of patellofemoral maltracking after total knee arthroplasty. Its precise effect on the patellofemoral mechanics has not been well quantified. We have developed an in vitro method to measure the influence of patellar maltracking on contact. Maltracking was induced by progressively rotating the femoral component either internally or externally. The contact mechanics were analysed using Tekscan. The results showed that excessive malrotation of the femoral component, both internally and externally, had a significant influence on the mechanics of contact. The contact area decreased with progressive maltracking, with a concomitant increase in contact pressure. The amount of contact area that carries more than the yield stress of ultra-high molecular weight polyethylene significantly increases with progressive maltracking. It is likely that the elevated pressures noted in malrotation could cause accelerated and excessive wear of the patellar button.

When performing the Scandinavian Total Ankle Replacement (STAR), the positioning of the talar component and the selection of mobile-bearing thickness are critical. A biomechanical experiment was undertaken to establish the effects of these variables on the range of movement (ROM) of the ankle.

Six cadaver ankles containing a specially-modified STAR prosthesis were subjected to ROM determination, under weight-bearing conditions, while monitoring the strain in the peri-ankle ligaments. Each specimen was tested with the talar component positions in neutral, as well as 3 and 6 mm of anterior and posterior displacement. The sequence was repeated with an anatomical bearing thickness, as well as at 2 mm reduced and increased thicknesses. The movement limits were defined as 10% strain in any ligament, bearing lift-off from the talar component or limitations of the hardware.

Both anterior talar component displacement and bearing thickness reduction caused a decrease in plantar flexion, which was associated with bearing lift-off. With increased bearing thickness, posterior displacement of the talar component decreased plantar flexion, whereas anterior displacement decreased dorsiflexion.