In-Shoe Sensor Measures of Loading Asymmetry during Gait as a Predictor of Frailty Development in Community-Dwelling Older Adults.

Clinical walk tests may not predict the development of frailty in healthy older adults. With advancements in wearable technology, it may be possible to predict the development of frailty using loading asymmetry parameters during clinical walk tests. This prospective cohort study aimed to test the hypothesis that increased limb loading asymmetry predicts frailty risk in community-living older adults. Sixty-three independently ambulant community-living adults aged ≥ 65 years were recruited, and forty-seven subjects completed the ten-month follow-up after baseline. Loading asymmetry index of net and regional (forefoot, midfoot, and rearfoot) plantar forces were collected using force sensing insoles during a 10 m walk test with their maximum speed. Development of frailty was defined if the participant progressed from baseline at least one grading group of frailty at the follow-up period using the Kihon Checklist. Fourteen subjects developed frailty during the follow-up period. Increased risk of frailty was associated with each 1% increase in loading asymmetry of net impulse (Odds ratio 1.153, 95%CI 1.001 to 1.329). Net impulse asymmetry significantly correlated with asymmetry of peak force in midfoot force. These results indicate the feasibility of measuring plantar forces of gait during clinical walking tests and underscore the potential of using load asymmetry as a tool to augment frailty risk assessment in community-dwelling older adults.

Detecting differences in limb load asymmetry during walking between older adult fallers and non-fallers using in-shoe sensors.

BACKGROUND: Previous studies have reported that clinical walk tests could not detect differences between fallers and non-fallers in older adults. With advancements in wearable technology, it may be possible to assess differences in loading parameters in clinical settings using portable data collection methods. RESEARCH QUESTION: The purpose of this study was to determine if wearable sensors (loadsol®) are reliable for assessing asymmetry of contact time, peak force, loading rate (LR), and impulse in older adults and determine if the insole can detect differences in these parameters between fallers and non-fallers during walking. METHODS: Fifty-five older adults (74.1 ± 6.1 years) walked at their maximum speed on a flat floor. Force data were collected from insoles (100 Hz) during a 10-m walk test. To assess reliability, an intraclass correlation coefficient [ICC(2,k)] was generated for each asymmetry variable. To determine differences between fallers and non-fallers, analysis of covariance (ANCOVA; covariate: body mass index) was completed for each variable. RESULTS: The ICC of peak force asymmetry (PFA) was 0.942, but other ICCs were less than 0.75. The ANCOVA results indicate that the loadsol® can detect differences in PFA between fallers and non-fallers. The PFA was significantly greater in fallers than in non-fallers. SIGNIFICANCE: The ability to collect force data while walking using loadsol® has the potential to broaden the research questions investigated, explore clinical applications, and increase generalizability.

The effect of a shoe lift on tensor fasciae latae length during standing with an artificial functional leg length discrepancy: An ultrasonic shear wave elastography study.

BACKGROUND: Shortening of tensor fasciae latae is one factor that causes a functional leg length discrepancy. A shoe lift has been used to correct the compensatory posture resulting from the discrepancy. Despite the potential therapeutic benefit of a shoe lift, the mechanism by which it exerts its effect is unclear. OBJECTIVE: To investigate the effect of a shoe lift on tensor fasciae latae length during standing with an artificial functional leg length discrepancy using ultrasonic shear wave elastography. METHODS: Twenty-two healthy individuals performed static standing under three conditions: drop of the pelvis and flexion of the leg resulting from fixing in the hip abduction position using a hip orthosis (functional leg length discrepancy condition); drop of the pelvis by the orthosis, but no flexion of the leg due to a shoe lift (shoe lift condition); and normal bilateral standing condition. The shear elastic modulus of tensor fasciae latae was calculated using ultrasonic shear wave elastography. RESULTS: The shear elastic modulus was significantly lower in the functional leg length discrepancy condition than in the shoe lift and normal conditions (p= 0.038). CONCLUSIONS: Using a shoe lift for the functional leg length discrepancy can result in a functional hip position that elongates tensor fasciae latae.

A Patient with a Unilateral Insular Lesion Showing Bilaterally Reduced Perception of Noxious Stimulation.

No study has reported a unilateral localized cerebral lesion of the posterior insula bilaterally reducing noxious stimuli perception. A 57-year-old man with an infarct involving the right posterior insula presented with reduced somatosensory response in the upper and lower left extremities. Furthermore, there was a reduced response to noxious stimulation in the right upper and lower limbs. We noted reductions in pain, noxious heat and cold perceptions, and sensitivity to increasing temperature. Other somatic sensations, including non-noxious temperatures, remained intact in the right upper and lower extremities. These findings in our patient with a unilateral insular lesion indicated a bilaterally reduced perception of noxious stimulation.

Effects of restriction of forefoot rocker functions by immobilisation of metatarsophalangeal joints on kinematics and kinetics during walking.

OBJECTIVE: This study was conducted to investigate the effects of restriction of forefoot rocker (FFR) functions by immobilisation of unilateral metatarsophalangeal joints (MPJs) on kinematic and kinetic factors during walking. METHODS: Eighteen healthy young adults participated in this study. To immobilise the MPJs of the right leg, an aluminium sole plate (AS) was fixed on the sole of the foot. Kinematic and kinetic data were collected while each subject walked at a comfortable speed with the AS and without. RESULTS: In the AS condition, the walking speed and contralateral step length were significantly decreased, and an asymmetrical centre of mass (COM) movement was observed. The range of plantarflexion motion and positive work by the ankle joint were decreased markedly during the late stance of the AS limb. In contrast, maximum hip and knee flexion angles in the swing phase of the AS limb and positive work by the bilateral hip joints over the gait cycle were increased. CONCLUSIONS: The results suggested that MPJ immobilisation may result in marked motion limitation of ankle plantarflexion and inhibition of push-off by the ankle joint despite no restrictions on the ankle joint. These changes may interfere with gait speed and a smooth and symmetrical COM shift during walking.

Analysis of Vertical Micro Acceleration While Standing Reveals Age-Related Changes.

In this study, we investigated the fluctuation characteristics of micro vertical acceleration of center of mass (vCOMacc) in standing and examined the usefulness of vCOMacc as an aging marker for standing control abilities. Sixteen young and 18 older adults participated in this experiment. Data for vCOMacc were calculated as the vertical ground reaction force value divided by each participant's body mass using a force plate. The COMacc frequency structure was determined using the continuous wavelet transform to analyze the relative frequency characteristics. For time domain analysis, we determined the root mean square (RMS) and maximum amplitude (MA) of the integrated power spectral density. We also analyzed the correlation between vCOMacc and lower limb muscle activity. The relative frequency band of vCOMacc was higher in older than young adults, and the time domain indicators were sufficient to distinguish the effects of aging. Regarding the relationship between vCOMacc during standing and muscle activity, a correlation was found with the soleus muscle in young adults, while it was moderately correlated with the gastrocnemius muscle in older adults. The cause of vCOM may be related to differences in muscle activity, and vCOMacc may be utilized to more easily assess the effects of aging in standing control.

Evaluation of the activities of the medial and lateral heads of quadratus plantae in flexion movements of the lateral four toes using ultrasound real-time tissue elastography.

Quadratus plantae (QP), one of the plantar intrinsic foot muscles, assist plantarflexion of the lesser toes. QP has medial and lateral muscle heads with different anatomical structures. The two heads of this muscle may have different roles in foot function. Ultrasound real-time tissue elastography (RTE) measurements have allowed quantitative assessment of deep-layer muscle elasticity. The purpose of this study was to determine the activity of the QP in flexion movements of the lateral four toes using RTE. Thirteen healthy subjects performed maximal voluntary contractions using a hand-held dynamometer with external belt fixation for each toe flexion movement. The elasticity of the muscles were measured using RTE during rest and flexion of each toe. The strain ratio of the muscle to that in an acoustic coupler was calculated as an index of muscle elasticity. Higher strain ratio values imply lower elasticity. The strain ratio of the medial head of QP for second toe flexion (0.10±0.11) was significantly stiffer than at rest (0.34±0.33). The strain ratios of the lateral head of QP for flexion of the second (0.32±0.19), third (0.41±0.37), fourth (0.33±0.26), and fifth (0.45±0.39) toes were significantly stiffer than at rest (1.02±0.68). These results suggest that the medial head of QP has a role in assisting second-toe flexion, and the lateral head has a role in assisting flexion of all four lateral toes.

The Effectiveness of Specific Exercise Approach or Modifiable Heel Lift in the Treatment of Functional Leg Length Discrepancy in Early Post-surgery Inpatients after Total Hip Arthroplasty: A Randomized Controlled Trial with a PROBE design.

OBJECTIVE: This study investigated the effectiveness of a specific exercise approach (SEA) or modifiable heel lift (MHL) to improve functional leg length discrepancy (LLD) after total hip arthroplasty (THA). METHODS: The study was a randomized controlled trial with a PROBE (prospective, randomized, open, blinded-endpoint) design trial. Patients (n=33) with both functional and perceived LLDs, 1 week after THA, were randomized to the SEA, MHL, or control groups. Patients in the SEA group performed 2 weeks of exercises to improve hip contracture and lumbar scoliosis. Patients in the MHL group used an insole-type heel lift to correct functional LLD. The control group received normal postoperative care, comprising standard rehabilitation after THA. The primary outcomes were functional LLD, measured by a block test, and patient-perceived LLD at 3 weeks after the surgery. Secondary outcomes included the visual analog scale (VAS) for pain, the Timed Up and Go (TUG) test, and the Western Ontario and McMaster Universities Osteoarthritis index (WOMAC) at 3 weeks after the surgery. RESULTS: The functional LLDs (mean ± SD) for the SEA (3.3 ± 3.1 mm) and MHL (2.2 ± 2.1 mm) groups were significantly smaller than for the control group (6.4 ± 4.0 mm). The degree of patient-perceived LLD differed significantly between the SEA and the control groups (p=.005). CONCLUSIONS: SEA and MHL use, during early post-operative recovery, can produce relevant changes in functional LLD after THA.

True or apparent leg length discrepancy: which is a better predictor of short-term functional outcomes after total hip arthroplasty?

BACKGROUND AND PURPOSE: The associations between leg length discrepancy (LLD) and patient-perceived inequality and functional outcomes after total hip arthroplasty (THA) are unclear in the literature. The aim of this study was to determine the types of LLD after THA and to identify the best predictor of patient-perceived LLD and functional outcome in the short term after THA. METHODS: We subdivided LLD into true and apparent types and prospectively studied 53 consecutive patients undergoing unilateral primary THA to determine whether there is an association between the type of LLD and functional outcome 2 months after the operation. Apparent LLD was measured by the block test and true LLD was measured by hip radiography. We classified the patients into 4 groups: true, apparent, mixed, and no-LLD groups. The questionnaire included a visual analog scale of pain, the Western Ontario and McMaster Universities Osteoarthritis Index, and patient-perceived inequality. Physical performance was measured using walking speed and the Timed Up and Go test. RESULTS: The apparent and mixed LLD groups had a higher prevalence of patient-perceived inequality than the true and no-LLD groups. The results of physical performance showed that the walking speed of the mixed LLD group and the results of the Timed Up and Go Test of the apparent LLD group were significantly slower than those of the true LLD group. DISCUSSION: We suggested that the true LLD group may have a weak relationship with functional outcome after THA while the apparent LLD resulting from pelvic obliquity due to hip contracture or scoliosis is correlated with the short-term functional outcome after THA. CONCLUSION: Apparent LLD can be a better predictor of patient-perceived inequality and physical performance than true LLD.