Changes in foot progression angle during gait reduce the knee adduction moment and do not increase hip moments in individuals with knee osteoarthritis

People with knee osteoarthritis who adopt a modified foot progression angle (FPA) during gait often benefit from a reduction in the knee adduction moment and knee pain. It is unknown, however, whether changes in the FPA increase hip moments, a surrogate measure of hip loading, which may increase the risk of hip pain or osteoarthritis. This study examined how altering the FPA affects hip moments. Individuals with knee osteoarthritis walked on an instrumented treadmill with their baseline gait, 10° toe-in gait, and 10° toe-out gait. A musculoskeletal modeling package was used to compute joint moments from the experimental data. Fifty participants were selected from a larger study who reduced their peak knee adduction moment with a modified FPA. In this group, participants reduced the first peak of the knee adduction moment by 7.6% with 10° toe-in gait and reduced the second peak by 11.0% with 10 ° toe-out gait. Modifying the FPA reduced the early-stance hip abduction moment, at the time of peak hip contact force, by 4.3% ± 1.3% for 10° toe-in gait (p=0.005) and by 4.6% ± 1.1% for 10° toe-out gait (p<0.001) without increasing the flexion and internal rotation moments (p>0.15). In summary, when adopting a FPA modification that reduced the knee adduction moment, participants did not increase surrogate measures of hip loading.

Spatiotemporal, Kinematic and Kinetic Assessment of the Effects of a Foot Drop Stimulator for Home-Based Rehabilitation of Patients with Chronic Stroke -- A Three-Dimensional Motion Analysis

Background: Gait disability affects the daily lives of patients with stroke in both home and community settings. An abnormal foot–ankle position can cause instability on the supporting surface and negatively affect gait. Our research team explored the ability of a portable peroneal nerve-targeting electrical stimulator to improve gait ability by adjusting the foot–ankle position during walking in patients with chronic stroke undergoing home-based rehabilitation. Methods: This was a double-blinded, parallel-group randomized controlled trial. Thirty-one patients with chronic stroke and ankle–foot motor impairment were randomized to receive 3 weeks of gait training, which involved using the transcutaneous peroneal nerve stimulator while walking (tPNS group; n = 16, mean age: 52.25 years), or conventional home and/or community gait training therapy (CT group; n = 15, mean age: 54.8 years). Functional assessments were performed before and after the 3-week intervention. The outcome measures included spatiotemporal gait parameters, three-dimensional kinematic and kinetic data on the ankle-foot joint, and a clinical motor and balance function assessment based on the Fugl–Meyer Assessment of Lower Extremity (FMA-LE) and Berg Balance scales (BBS). Additionally, 16 age-matched healthy adults served as a baseline control of three-dimensional gait data for both trial groups.Results: The FMA-LE and BBS scores improved in both the tPNS groups (p = .004 and .001, respectively) and CT groups (p = .034 and .028, respectively) from before to after training. Participants in the tPNS group exhibited significant differences in spatiotemporal gait parameters, including opposite foot off, double support, stride length, and walking speed, after training (p = .010, .042, .017 and .001, respectively). Additionally, the tPNS group exhibited significant differences in kinematic parameters, such as the ankle angle at the transverse plane (p = .021) and foot progression angle at the frontal plane (p = .009) upon initial contact, and the peak ankle joint angle at the transverse plane (p = .023) and foot progression angle at the frontal and transverse planes (p = .032 and .046, respectively) during gait cycles after 3 weeks of training.Conclusions: Use of a portable tPNS device during walking tasks appeared to improve spatiotemporal gait parameters and ankle and foot angles more effectively than conventional home rehabilitation in patients with chronic stroke. Although guidelines for home-based rehabilitation training services and an increasing variety of market devices are available, no evidence for improvement of motor function and balance was superior to conventional rehabilitation.Trial registration: Chictr, ChiCTR2000040137. Registered 22 November 2020, https://www.chictr.org.cn/showproj.aspx?proj=64424

Predicting Knee Adduction Moment Response to Gait Retraining with Minimal Clinical Data

Knee osteoarthritis is a progressive disease mediated by high joint loads. Foot progression angle modifications that reduce the knee adduction moment (KAM), a surrogate of knee loading, have demonstrated efficacy in alleviating pain and improving function. Although changes to the foot progression angle are overall beneficial, KAM reductions are not consistent across patients. Moreover, customized interventions are time-consuming and require instrumentation not commonly available in the clinic. We present a model that uses minimal clinical data to predict the extent of first peak KAM reduction after toe-in gait retraining. For such a model to generalize, the training data must be large and variable. Given the lack of large public datasets that contain different gaits for the same patient, we generated this dataset synthetically. Insights learned from ground-truth datasets with both baseline and toe-in gait trials (N=12) enabled the creation of a large (N=138) synthetic dataset for training the predictive model. On a test set of data collected by a separate research group (N=15), the first peak KAM reduction was predicted with a mean absolute error of 0.134% body weight * height (%BW*HT). This error is smaller than the test set’s subject average standard deviation of the first peak during baseline walking (0.306%BW*HT). This work demonstrates the feasibility of training predictive models with synthetic data and may provide clinicians with a streamlined pathway to identify a patient-specific gait retraining outcome without requiring gait lab instrumentation.

Gait Characteristics in Youth With Transverse Myelitis

Background: Transverse myelitis (TM) in childhood is a rare disorder characterized by the presence of spinal cord inflammation. Gait difficulty in children with TM is common; however, there is a paucity of literature regarding quantitative assessment of gait in children and adolescents with TM. Objectives: To characterize gait patterns in a cohort of ambulatory children with TM and age-matched, typically developing peers in order to better understand the functional mobility of patients diagnosed with childhood TM. Methods: This was a retrospective study of 26 ambulatory pediatric patients with a confirmed diagnosis of TM who had undergone three-dimensional, instrumented gait analysis (3D-IGA) at 3 years of age or older. A group of 38 typically developing children served as a control group. Results: Gait in children with TM was characterized by moderate kinematic deviations as measured by the Gait Deviation Index (GDI) and a crouched gait pattern (p &lt; .001), increased anterior pelvic tilt (p &lt; .001), decreased motion at the knees (p &lt; .001), and a wider base of support (foot progression angle, p &lt; .001). The TM group had a slower walking speed (p &lt; .001), shorter strides (p &lt; .001), and an increased stance phase compared to controls. Conclusion: Our study results showed moderate kinematic deviations quantified by the GDI. Overall, the gait pattern in the TM population tested had greater hip and knee flexion with wider foot progression angle. Identification of gait characteristics in children with TM is the first step in predicting changes in gait pattern as they mature over time, which may ultimately allow for targeted intervention to maintain their ambulatory function.

Influence of Foot Progression Angle on Center of Pressure During Stair Ascending in Subjects With Chronic Ankle Instability

The purpose of this study was to identify changes in the center of pressure during stair ascending in subjects with chronic ankle instability while different angles of foot are applied. The subjects of this study were 20 male and female adults with chronic ankle instability were selected from among the employees of D Hospital in Daegu Metropolitan City. The criteria for selection of subjects with chronic ankle instability were those who felt wobbling in the ankle joint and scored not higher than 24 points in a test using the Cumberland Ankle Instability Tool (CAIT). The subjects carried out stair ascending in neutral, toe-in and toe-out postures, respectively, and changes in the center of pressure (COP) were compared and analyzed. The results of this study, no statistically significant difference appeared in the comparison between the toe-in posture and neutral posture or between the neutral posture and the toe-out posture but medial/lateral movements of the center of pressure showed significant differences between the toe-in and toe-out postures. In addition, the total travel range and the moving range of the center of pressure, the average velocity, and the anterior/posterior movements of the center of pressure showed no statistically significant difference among all three postures. As a result, it could be seen that when adults with chronic ankle instability climb the stairs, the toe-in posture reduce the medial/lateral movements of the center of pressure thereby increasing the stability of the ankle and effectively preventing re-injuries.

Study of the Distortion of the Indirect Angular Measurements of the Calcaneus Due to Perspective: In Vitro Testing

The study of the foot is relevant in kinematic analyses of gait. Images captured through a lens can be subjected to various aberrations or distortions that affect the measurements. An in vitro study was performed with a rearfoot simulator to compare the apparent degrees (photographed) with the real ones (placed in the simulator) in the plane of the rearfoot’s orientation, according to variations in the capture angle in other planes of space (the sagittal plane and transverse plane—the latter determined by the foot progression angle). The following regression formula was calculated to correct the distortion of the image: real frontal plane = 0.045 + (1.014 × apparent frontal plane) − (0.018 × sagittal plane × foot progression angle). Considering the results of this study, and already knowing its angle in the transverse and sagittal planes, it is possible to determine the angle of a simulated calcaneus with respect to the ground in the frontal plane, in spite of distortions caused by perspective and the lack of perpendicularity, by applying the above regression formula. The results show that the angular measurements of a body segment made on frames can produce erroneous data due to the variation in the perspective from which the image is taken. This distortion must be considered when determining the real values of the measurements.

Foot progression angle estimation using a single foot-worn inertial sensor

Background The foot progression angle is an important measure used to help patients reduce their knee adduction moment. Current measurement systems are either lab-bounded or do not function in all environments (e.g., magnetically distorted). This work proposes a novel approach to estimate foot progression angle using a single foot-worn inertial sensor (accelerometer and gyroscope). Methods The approach uses a dynamic step frame that is recalculated for the stance phase of each step to calculate the foot trajectory relative to that frame, to minimize effects of drift and to eliminate the need for a magnetometer. The foot progression angle (FPA) is then calculated as the angle between walking direction and the dynamic step frame. This approach was validated by gait measurements with five subjects walking with three gait types (normal, toe-in and toe-out). Results The FPA was estimated with a maximum mean error of ~ 2.6° over all gait conditions. Additionally, the proposed inertial approach can significantly differentiate between the three different gait types. Conclusion The proposed approach can effectively estimate differences in FPA without requiring a heading reference (magnetometer). This work enables feedback applications on FPA for patients with gait disorders that function in any environment, i.e. outside of a gait lab or in magnetically distorted environments.