Attenuation of spinal transients at heel strike using viscoelastic heel insoles: an in vivo study

A model identification approach to quantify impact of whole-body vertical vibrations on limb compliant dynamics and walking stability

Extensive research is ongoing in the field of orthoses/exoskeleton design for efficient lower limbs assistance. However, despite wearable devices reported to improve lower limb mobility, their structural impacts on whole-body vertical dynamics have not been investigated. This study introduced a model identification approach and frequency domain analysis to quantify the impacts of orthosis-generated vibrations on limb stability and contractile dynamics. Experiments were recorded in the motion capture lab using 11 unimpaired subjects by wearing an adjustable ankle-foot orthosis (AFO). The lower limb musculoskeletal structure was identified as spring-mass (SM) and spring-mass-damper (SMD) based compliant models using the whole-body centre-of-mass acceleration data. Furthermore, Nyquist and Bode methods were implemented to quantify stabilities resulting from vertical impacts. Our results illustrated a significant decrease (p < 0.05) in lower limb contractile properties by wearing AFO compared with a normal walk. Also, stability margins quantified by wearing AFO illustrated a significant variance in terms of gain-margins (p < 0.05) for both loading and unloading phases whereas phase-margins decreased (p < 0.05) only for the respective unloading phases. The methods introduced here provide evidence that wearable orthoses significantly affect lower limb vertical dynamics and should be considered when evaluating orthosis/prosthesis/exoskeleton effectiveness.

Foot posture, leg length discrepancy and low back pain--their relationship and clinical management using foot orthoses--an overview

Mechanical low back pain (LBP) is a very common, expensive, and significant health issue in the western world. Functional musculoskeletal conditions are widely thought to cause mechanical low back pain. The role of foot posture and leg length discrepancy in contributing to abnormal biomechanics of the lumbopelvic region and low back pain is not sufficiently investigated. This critical review examines the evidence for the association between foot function, particularly pronation, and mechanical LBP. It also explores the evidence for a role for foot orthoses in the treatment of this condition. There is a body of evidence to support the notion that foot posture, particularly hyperpronation, is associated with mechanical low back pain. Mechanisms that have been put forward to account for this finding are based on either mechanical postural changes or alterations in muscular activity in the lumbar and pelvic muscles. More research is needed to explore and quantify the effects of foot orthoses on chronic low back pain, especially their effects on lumbopelvic muscle function and posture. The clinical implications of this work are significant since foot orthoses represent a simple and potentially effective therapeutic measure for a clinical condition of high personal and social burden.

Insole effects on impact loading during walking

Impact loading during walking has been associated with overuse related musculoskeletal disorders, such as osteoarthritis. This study was designed to determine the effect of two shoe insole designs on impact-related loading during walking. In total, 22 healthy adults walked along a 10-m walkway in three different insole conditions: (i) no insole; (ii) flat material insole; (iii) heel-cup insole. Impact forces at the ground were determined and estimated at the knee in a subset of participants (n = 14). Repeated measures ANOVA revealed a significant reduction in peak vertical ground reaction force (vGRF) with the flat material insole compared with the no insole and heel-cup conditions (p = 0.001). No differences between conditions were observed in vGRF loading rate (p > 0.05). Peak impact force at the knee was reduced with flat material insoles and heel-cup insoles (p < 0.05). These data indicate that reductions in impact forces during walking are dependent upon insole design. STATEMENT OF RELEVANCE: This study provides new evidence that impact loads are reduced with shoe insoles during walking. High impact loads are implicated in the development and progression of knee pathologies, including osteoarthritis. Thus, these findings indicate that insole use may be beneficial for various musculoskeletal disorders, including key public health problems such as osteoarthritis.

A novel biomechanical device improves gait pattern in patient with chronic nonspecific low back pain

STUDY DESIGN

A retrospective study on patients with chronic nonspecific low back pain (NSLBP).

OBJECTIVE

To describe the gait stride characteristics of patients with chronic NSLBP, and to examine the effect of a novel biomechanical device on the gait stride characteristics of these patients.

SUMMARY OF BACKGROUND DATA

Patient with NSLBP alters their gait patterns. This is considered a protective mechanism as patients try to avoid extensive hip and spine ranges of motion and minimize forces and moments acting on the body. In addition, there are changes in the neuromuscular control system in patients with LBP that could possibly be attributed to the effects of pain on motor control.

METHODS

Nineteen patients underwent a gait test, using an electronic walkway, at baseline and after 12 weeks of treatment. Spatiotemporal parameters were used to identify changes in gait pattern. A novel biomechanical device comprised of 4 modular elements attached to foot-worn platforms was used in the study. The modules are 2 convex shaped biomechanical elements attached to each foot, one is located under the hindfoot region and the other is located under the forefoot region. The device was individually calibrated to each patient. The patients were instructed to walk with the calibrated biomechanical device on a daily basis for a period of 12 weeks.

RESULTS

Significant differences were found at baseline and after 12 weeks in normalized velocity (P = 0.03), cadence (P < 0.01), left normalized step length (P = 0.02), right normalized step length (P = 0.02), right swing (P < 0.01), right stance (P < 0.01), left single limb support (P = 0.01), left double limb support (P = 0.02), and right double limb support (P = 0.02).

CONCLUSION

Patients with NSLBP treated with the novel biomechanical device for 3 months increased walking speed through longer step length and eliminated asymmetrical differences.

Knee osteoarthritis: primary care using noninvasive devices and biomechanical principles

Osteoarthritis (OA) is an epidemic for which there is no known cure. There is enormous popular demand for noninvasive and nonpharmacologic therapies for OA, and there is a pressing need for primary care physicians to respond by updating their pattern of practice. Despite increasing concern about the capacity of our health care system to meet rising demands, routine primary care for knee OA has changed little over several decades. This article introduces physicians to many of the most important noninvasive devices used in the conservative management of symptomatic knee OA.

Application of principal component analysis in vertical ground reaction force to discriminate normal and abnormal gait

Discrete parameters from ground reaction force (GRF) are been considered in gait analysis studies. However, principal component analysis (PCA) may provide additional insight into gait analysis for considering the complete pattern of GRF. This study aimed at testing the application of PCA to discriminate the vertical GRF pattern between control group (CG) and patients with lower limb fractures (FG), as well as proposing a score to quantify the abnormality of gait. Thirty-eight healthy subjects participated of CG and 13 subjects in FG, five subjects from FG were also evaluated after physiotherapeutic treatment (FGA). The GRF was measured by an instrumented treadmill. Principal component coefficients (PCCs) were obtained by singular value decomposition using GRF of complete stride. Two, four and six PCCs were used to obtain the standard distance (D). The classification between groups was mainly given by the first PC, which indicated higher loading factors during push off of affected side and heel strike of unaffected side. The classification performance achieved 92.2% accuracy with two PCCs, 94.1% with four PCCs and 96.1% with six PCCs. Four subjects reached normal boundary after treatment, with all FGA subjects presenting decreased D. This study demonstrates that PCA is an adequate method for discriminating normal and abnormal gait and D allows an objective evaluation of the progress and effectiveness of rehabilitation treatment.

Accelerometry: a technique for quantifying movement patterns during walking

The popularity of using accelerometer-based systems to quantify human movement patterns has increased in recent years for clinicians and researchers alike. The benefits of using accelerometers compared to more traditional gait analysis instruments include low cost; testing is not restricted to a laboratory environment; accelerometers are small, therefore walking is relatively unrestricted; and direct measurement of 3D accelerations eliminate errors associated with differentiating displacement and velocity data. However, accelerometry is not without its disadvantages, an issue which is scarcely reported in gait analysis literature. This paper reviews the use of accelerometer technology to investigate gait-related movement patterns, and addresses issues of acceleration measurement important for experimental design. An overview of accelerometer mechanics is provided before illustrating specific experimental conditions necessary to ensure the accuracy of gait-related acceleration measurement. A literature review is presented on how accelerometry has been used to examine basic temporospatial gait parameters, shock attenuation, and segmental accelerations of the body during walking. The output of accelerometers attached to the upper body has provided useful insights into the motor control of normal walking, age-related differences in dynamic postural control, and gait patterns in people with movement disorders.

Effects of insoles and additional shock absorption foam on the cushioning properties of sport shoes

The purpose of this study was to investigate the effects of insoles and additional shock absorption foam on the cushioning properties of various sport shoes with an impact testing method. Three commercial sport shoes were used in this study, and shock absorption foam (TPE5020; Vers Tech Science Co. Ltd., Taiwan) with 2-mm thickness was placed below the insole in the heel region for each shoe. Eight total impacts with potential energy ranged from 1.82 to 6.08 J were performed onto the heel region of the shoe. The order of testing conditions was first without insole, then with insole, and finally interposing the shock absorption foam for each shoe. Peak deceleration of the striker was measured with an accelerometer attached to the striker during impact. The results of this study seemed to show that the insole or additional shock absorption foam could perform its shock absorption effect well for the shoes with limited midsole cushioning. Further, our findings showed that insoles absorbed more, even up to 24-32% of impact energy under low impact energy. It seemed to indicate that insoles play a more important role in cushioning properties of sport shoes under a low impact energy condition.

Effect of a shock-absorbing pylon on transmission of heel strike forces during the gait of people with unilateral trans-tibial amputations: a pilot study

The primary objective was to test the hypothesis that walking with a shock-absorbing pylon (SAP) decreases the peak magnitude and frequency content of the heel-strike-initiated shock wave transmitted to the stump. The secondary hypotheses were that walking with a SAP decreases the heel-strike transient force between the ground and the foot and increases function as measured by walking velocity and subjective assessments. Seven people with unilateral trans-tibial amputations walked at self-selected speeds without and with a SAP. As the primary outcome measure, accelerometers were used mounted proximally and distally along the prosthetic pylon to measure the transmitted shock wave. Secondary measures included ground reaction forces from a force plate, a ten-minute walking test to determine walking speed and a questionnaire to evaluate gait function and subjective preference. The SAP provided no significant shock absorption as indicated by either the mean peak proximal accelerations of 3.19 g and 2.82 g (p = 0.28) without and with the SAP respectively or the mean difference between the peak proximal and distal accelerometers, 0.16 g and 0.19 g (p = 0.58). No significant change in the frequency content was found. Variances were high. There were no significant differences noted in the secondary measures. Although this study failed to identify any statistically significant effects due to the SAP, the magnitude and variance of the data will permit an accurate estimation of the appropriate sample size for future studies required to determine the efficacy of SAPs.