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

Summary Statement. Simulated increases in body weight led to increased displacement, von Mises stress, and contact pressure in finite element models of the extended and flexed knee. Contact shifted to locations of typical medial osteoarthritis lesions in the extended knee models. Introduction. Obesity is commonly associated with increased risk of osteoarthritis (OA). The effects of increases in body weight and other loads on the stresses and strains within a joint can be calculated using finite element (FE) models. The specific effects for different individuals can be calculated using subject-specific FE models which take individual geometry and forces into account. Model results can then be used to propose mechanisms by which damage within the joint may initiate. Patients & Methods. Twelve subject-specific FE models (Abaqus 6.11) of three normal healthy subjects were created by combining geometry (3T T1-weighted MRI scans processed using Mimics 13.0, Geomagic Studio 11, and SolidWorks 2010) and load cases (Vicon and AMTI motion analysis data processed within AnyBody Technology Version 3.0 and Matlab R2007a). Model geometry included the femur and tibia (rigid bodies), tibial cartilage and femoral cartilage (E = 12 MPa, ν = 0.45), and menisci (E. circumferential. = 120 MPa, ν. circumferential. = 0.2; E. axial/radial. = 20 MPa, ν. axial/radial. = 0.3). The tibia was held fixed while loads were applied to the centre of mass of the femur. Frictional contact (µ = 0.02) was modelled between soft tissues. Of the twelve models, six were of extended knees and six were of mid-range flexed (∼50°) knees. Each of these six models represented a paired set: a “normal” model and an “increased-load” model. In the flexed knee “increased-load” models, loads were doubled; in the extended knee “increased-load” models, loads were increased to a standard 2000 N compressive load across the joint (approximately three to four times larger than the original loads). Maximum displacements, von Mises stresses, and contact pressures on the articulating tibial cartilage and femoral cartilage surfaces were calculated; results of the “normal” and “increased-load” models were compared. Results. Increasing the applied loads increased the maximum displacements, von Mises stresses, and contact pressures. Contact shifted anteriorly in the extended knee models to typical locations of medial OA cartilage lesions. No contact shift occurred in the flexed knee models; contact remained in typical locations of lateral OA cartilage lesions, but the contact area extended in all directions, and displacements, stresses, and pressures increased. Discussion/Conclusion. Comparing the “normal” and “increased-load” results suggested two potential mechanical mechanisms involved in osteoarthritic cartilage lesion development. Contact shifted to areas of previously-unloaded cartilage in the extended knee “increased-load” models. Cartilage has regional material properties, with stiffer cartilage in areas of frequent contact and loading; shifting contact to areas of less-stiff cartilage could damage the cartilage and lead to degenerative diseases such as OA. Contact did not shift in the flexed knee “increased-load” models. Instead, the displacements, stresses, and pressures increased while the centres of contact remained relatively stationary. If these contact variables increase beyond a threshold magnitude, the cartilage could be damaged, potentially leading to OA

Background. Balance impairment and falling are of the major health problems in elderly individuals. The ability to maintain standing balance influences the risk of falling while performing everyday activities. Postural control is the base of balance that is the result of collaboration of visual, vestibular and somatosensory systems. Single leg stance test is a simple clinical method to evaluate static balance. In this test, the center of body mass is on a small support level and need to make corrective movements to create balance by postural control system. Kinesiotaping and stretching of ankle plantar flexor muscles used in physical therapy are effective in improvement of postural balance. Kinesiotaping is effective in maintaining balance by activates cutaneous receptors and promoting alpha motor neuron stimulation. Moreover, stretching is a common treatment used to prevent muscle shortness and increase the range of motion that improves the balance. Aim. Therefore the aim of current study was to compare the effects of these two methods in elderly women and men on ankle plantar flexor muscles which are effective to maintain postural status. Materials and Methods. In a single blind randomized clinical trial, 20 elderly male and 20 elderly female were assigned into 2 groups of kinesiotaping and stretching. Inhibitory Y shape tape was applied on the gastrocnemius in first group. In the stretching group, the muscle was stretched for 60 seconds by 4 times. The static balance was examined before and after the interventions by using single leg stance test. In this test, the subjects were asked to stand bare foot on dominant limb and cross their arms over chest. A maximum time for this test is 30 seconds. The researcher who was assessing balance was unaware to the intervention group. Results. According to paired t-test, Despite progress in time to stance on one leg after the interventions, the changes were not significant (P>0.05). Although the trend was more pronounced in the stretching group, independent t-test results showed no significant difference between groups (P>0.05). While in any of the treatment groups, there was no difference between men and women (P=0.1 and P=0.7 for kinesiotaping and stretching group, respectively). Conclusion. While the results did not show any significant difference after the intervention, but Increasing of the test time, which means improving the balance of participants, is evident. However, changes in the stretching group were more pronounced. Keyword. Single leg stance test, Elderly, Stretching, kinesiotaping, Plantar flexor muscle

Objectives

Taper junctions between modular hip arthroplasty femoral heads and stems fail by wear or corrosion which can be caused by relative motion at their interface. Increasing the assembly force can reduce relative motion and corrosion but may also damage surrounding tissues. The purpose of this study was to determine the effects of increasing the impaction energy and the stiffness of the impactor tool on the stability of the taper junction and on the forces transmitted through the patient’s surrounding tissues.