IMU-derived kinematics detect gait differences with age or knee osteoarthritis but differ from marker-derived inverse kinematics

Common in-lab, marker-based gait analyses may not represent daily, real-world gait. Real-world gait analyses may be feasible using inertial measurement units (IMUs), especially with recent advancements in open-source methods (e.g., OpenSense). Before using OpenSense to study real-world gait, we must determine whether these methods: (1) estimate joint kinematics similarly to traditional marker-based motion capture (MoCap) and (2) differentiate groups with clinically different gait mechanics. Healthy young and older adults and older adults with knee osteoarthritis completed this study. We captured MoCap and IMU data during overground walking at self-selected and faster speeds. MoCap and IMU kinematics were computed with appropriate OpenSim workflows. We tested whether sagittal kinematics differed between MoCap- and IMU-derived data, whether tools detected between-group differences similarly, and whether kinematics differed between tools by speed. MoCap data showed more flexion than IMU data (hip: 0-47 and 65-100% stride, knee: 0-38 and 58-91% stride, ankle: 18-100% stride). Group kinematics differed at the hip (young extension > knee osteoarthritis at 30-47% stride) and ankle (young plantar flexion > older healthy at 62-65% stride). Group-by-tool interactions occurred at the hip (61-63% stride). Significant tool-by-speed interactions were found, with hip and knee flexion increasing more for MoCap than IMU data with speed (hip: 12-15% stride, knee: 60-63% stride). While MoCap- and IMU-derived kinematics differed, our results suggested that the tools similarly detected clinically meaningful differences in gait. Results of the current study suggest that IMU-derived kinematics with OpenSense may enable the valid and reliable evaluation of gait in real-world, unobserved settings.

The Effect of Obesity Class on the Energetics and Mechanics of Walking

Higher mass-normalized net energy cost of walking (NetCw/kg) and mechanical pendular recovery are observed in obese compared to lean adults. This study aimed to investigate the effect of different classes of obesity on the energetics and mechanics of walking and to explore the relationships between body mass, NetCw/kg and gait mechanics by using principal component analysis (PCA). NetCw/kg and gait mechanics were computed in severely obese (SOG; n = 18, BMI = 40.1 ± 4.4 kg·m−2), moderately obese (MOG; n = 17, BMI = 32.2 ± 1.5 kg·m−2) and normal-weight (NWG; n = 13, BMI = 22.0 ± 1.5 kg·m−2) adults during five walking trials (0.56, 0.83, 1.11, 1.39, 1.67 m·s−1) on an instrumented treadmill. NetCw/kg was significantly higher in SOG compared to NWG (p = 0.019), with no significant difference between SOG and MOG (p = 0.14), nor between MOG and NWG (p = 0.27). Recovery was significantly higher in SOG than in NWG (p = 0.028), with no significant difference between SOG and MOG (p = 0.13), nor between MOG and NWG (p = 0.35). PCA models explained between 17.0% and 44.2% of the data variance. This study showed that: (1) obesity class influences the gait energetics and mechanics; (2) PCA was able to identify two components, showing that the obesity class is associated with lower walking efficiency and better pendulum-like characteristics.

Effects of obesity and foot arch height on gait mechanics: A cross-sectional study

Foot arch structure contributes to lower-limb joint mechanics and gait in adults with obesity. However, it is not well-known if excessive weight and arch height together affect gait mechanics compared to the effects of excessive weight and arch height alone. The purpose of this study was to determine the influences of arch height and obesity on gait mechanics in adults. In this study, 1) dynamic plantar pressure, 2) spatiotemporal gait parameters, 3) foot progression angle, and 4) ankle and knee joint angles and moments were collected in adults with normal weight with normal arch heights (n = 11), normal weight with lower arch heights (n = 10), obesity with normal arch heights (n = 8), and obesity with lower arch heights (n = 18) as they walked at their preferred speed and at a pedestrian standard walking speed, 1.25 m/s. Digital foot pressure data were used to compute a measure of arch height, the Chippaux-Smirak Index (CSI). Our results revealed that BMI and arch height were each associated with particular measures of ankle and knee joint mechanics during walking in healthy young adults: (i) a higher BMI with greater peak internal ankle plantar-flexion moment and (ii) a lower arch height with greater peak internal ankle eversion and abduction moments and peak internal knee abduction moment (i.e., external knee adduction moment). Our results have implications for understanding the role of arch height in reducing musculoskeletal injury risks, improving gait, and increasing physical activity for people living with obesity.

Transtibial limb loss does not increase metabolic cost in three-dimensional computer simulations of human walking

Loss of a lower limb below the knee, i.e., transtibial limb loss, and subsequently walking with a prosthesis, is generally thought to increase the metabolic cost of walking vs. able-bodied controls. However, high-functioning individuals with limb loss such as military service members often walk with the same metabolic cost as controls. Here we used a 3-D computer model and optimal control simulation approach to test the hypothesis that transtibial limb loss in and of itself causes an increase in metabolic cost of walking. We first generated N = 36 simulations of walking at 1.45 m/s using a “pre-limb loss” model, with two intact biological legs, that minimized deviations from able-bodied experimental walking mechanics with minimum muscular effort. We then repeated these simulations using a “post-limb loss” model, with the right leg’s ankle muscles and joints replaced with a simple model of a passive transtibial prosthesis. No other changes were made to the post-limb loss model’s remaining muscles or musculoskeletal parameters compared to the pre-limb loss case. Post-limb loss, the gait deviations on average increased by only 0.17 standard deviations from the experimental means, and metabolic cost did not increase (3.58 ± 0.10 J/m/kg pre-limb loss vs. 3.59 ± 0.12 J/m/kg post-limb loss, p = 0.65). The results suggest that transtibial limb loss does not directly lead to an increase in metabolic cost, even when deviations from able-bodied gait mechanics are minimized. High metabolic costs observed in individuals with transtibial limb loss may be due to secondary changes in strength or general fitness after limb loss, modifiable prosthesis issues, or to prioritization of factors that affect locomotor control other than gait deviations and muscular effort.

Lower Limb Proprioception and Strength Differences Between Adolescents With Autism Spectrum Disorder and Neurotypical Controls

Autism spectrum disorder (ASD) is a complex diagnosis characterized primarily by persistent deficits in social communication/interaction and repetitive behavior patterns, interests, and/or activities. ASD is also characterized by various physiological and/or behavioral features that span sensory, neurological, and neuromotor function. Although problems with lower body coordination and control have been noted, little prior research has examined lower extremity strength and proprioception, a process requiring integration of sensorimotor information to locate body/limbs in space. We designed this study to compare lower limb proprioception and strength in adolescents with ASD and neurotypical controls. Adolescents diagnosed with ASD (n = 17) and matched controls (n = 17) performed ankle plantarflexion/dorsiflexion bilateral proprioception and strength tests on an isokinetic dynamometer. We assessed position-based proprioception using three targeted positions (5 and 20-degrees plantarflexion and 10-degrees dorsiflexion) and speed-based proprioception using two targeted speeds (60 and 120-degrees/second). We assessed strength at 60-degrees/second. Participants with ASD performed 1.3-times more poorly during plantarflexion position and 2-times more poorly during the speed-based proprioception tests compared to controls. Participants with ASD also exhibited a 40% reduction in plantarflexion strength compared to controls. These findings provide insight into mechanisms that underly the reduced coordination, aberrant gait mechanics, and coordination problems often seen in individuals with ASD, and the identification of these mechanisms now permits better targeting of rehabilitative goals in treatment programs.

The Effects of Posture on the Three-Dimensional Gait Mechanics of Human Walking in Comparison to Bipedal Chimpanzees

Humans walk with an upright posture on extended limbs during stance and with a double-peaked vertical ground reaction force. Our closest living relatives, chimpanzees, are facultative bipeds that walk with a crouched posture on flexed, abducted hind limbs and with a single-peaked vertical ground reaction force. Differences in human and bipedal chimpanzee three-dimensional kinematics have been well quantified; however, it is unclear what the independent effects of using a crouched posture are on three-dimensional gait mechanics for humans, and how they compare with chimpanzees. Understanding the relationships between posture and gait mechanics, with known differences in morphology between species, can help researchers better interpret the effects of trait evolution on bipedal walking. We quantified pelvis and lower limb three-dimensional kinematics and ground reaction forces as humans adopted a series of upright and crouched postures and compared them with data from bipedal chimpanzee walking. Human crouched posture gait mechanics were more similar to bipedal chimpanzee gait than normal human walking, especially in sagittal plane hip and knee angles. However, there were persistent differences between species, as humans walked with less transverse plane pelvis rotation, less hip abduction, and greater peak horizontal ground reaction force in late stance than chimpanzees. Our results suggest that human crouched posture walking reproduces only a small subset of the characteristics of three-dimensional kinematics and ground reaction forces of chimpanzee walking, with the remaining differences likely due in large part to the distinct musculoskeletal morphologies of humans and chimpanzees.

Multiple Bony Deformities and Short Stature in a Child with Lamellar Ichthyosis, What more can we do? A Case Report

Introduction: Ichthyosis is a group of disorders typically characterized by the accumulation of large scales over the skin. Mild bony deformities due to Vitamin D deficiency are commonly associated with this group of disorders which can be successfully treated with conventional Vitamin D supplementation. Severe multiple bony deformities requiring surgical correction are rarely reported and may be associated with various other disorders. Case Report: We report a case of a 15-year-old male with ichthyosis, short stature, and progressive multiple bony deformities since birth. The child was started on Vitamin D3 supplementation. Once biochemical parameters improved he underwent multiple corrective osteotomies in the bilateral tibia and right femur to improve gait mechanics. Our main concerns while managing the patient were regarding wound healing, secondary infection due to extensive scaling and healing at the osteotomy site. On follow-up we noted good healing at the osteotomy site without any surgical site infection or skin complications as well as improvement in gait mechanics and cosmesis. Conclusion: Severe bony deformities due to Vitamin D deficient are rare in ichthyosis and other syndromic causes should be ruled out. Surgical management can be beneficial in improving quality of life and gait biomechanics. Keywords: Lamellar ichthyosis, osteotomy, genetic testing, Vitamin D deficiency.