Dataset Information

Knee extension moment arm variations relate to mechanical function in walking and running.

ABSTRACT: The patellofemoral joint plays a crucial mechanical role during walking and running. It increases the knee extensor mechanism's moment arm and reduces the knee extension muscle forces required to generate the extension moment that supports body weight, prevents knee buckling and propels the centre of mass. However, the mechanical implications of moment arm variation caused by patellofemoral and tibiofemoral motion remain unclear. We used a data-driven musculoskeletal model with a 12-degree-of-freedom knee to simulate the knee extension moment arm during walking and running. Using a geometric method to calculate the moment arm, we found smaller moment arms during running than during walking in the swing phase. Overall, knee flexion causes differences between running and walking moment arms as increased flexion causes a posterior shift in the tibiofemoral rotation axis and patella articulation with the distal femur. Moment arms were also affected by knee motion direction and best predicted by separating by direction instead of across the entire gait cycle. Furthermore, we found high inter-subject variation in the moment arm that was largely explained by out-of-plane motion. Our results are consistent with the concept that shorter moment arms increase the effective mechanical advantage of the knee and may contribute to increased running velocity.

SUBMITTER: Wheatley MGA

PROVIDER: S-EPMC8371375 | biostudies-literature | 2021 Aug

REPOSITORIES: biostudies-literature

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Knee extension moment arm variations relate to mechanical function in walking and running.

Wheatley Mitchell G A MGA Thelen Darryl G DG Deluzio Kevin J KJ Rainbow Michael J MJ

Journal of the Royal Society, Interface 20210818 181

The patellofemoral joint plays a crucial mechanical role during walking and running. It increases the knee extensor mechanism's moment arm and reduces the knee extension muscle forces required to generate the extension moment that supports body weight, prevents knee buckling and propels the centre of mass. However, the mechanical implications of moment arm variation caused by patellofemoral and tibiofemoral motion remain unclear. We used a data-driven musculoskeletal model with a 12-degree-of-fr ...[more]

PMID: 34404228

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Project description:BackgroundKnee pain is one of the main problems associated with knee osteoarthritis. The peak external knee adduction moment (KAM) in gait is commonly used to estimate medial knee loading, and elevated KAM has been related to a higher risk of developing knee pain in older adults. Although knee flexion moment (KFM) also contributes to medial knee loading, its role in the development of knee pain remains unclear.AimTo investigate the association between knee moments and the incidence of knee pain in 24 months in asymptomatic older adults.DesignProspective cohort study.SettingUniversity laboratory.PopulationCommunity-dwelling adults aged 60-80 years were recruited. We excluded participants with knee pain/known arthritis, knee injury, knee/hip joint replacement, cognitive impairment, or neurological conditions.MethodsThree-dimensional gait analysis was conducted to compute the peak KFM and KAM. Telephone surveys were conducted 12 and 24 months after the baseline assessment. Self-reported knee pain and its intensity and frequency were captured. Logistic regression with generalized estimating equations was used to examine associations between knee moments and the risk of knee pain.ResultsOf the 162 eligible participants who completed the baseline assessment (age: 65.8±4.0 years, 61.1% females), 157 and 138 were also assessed for incident knee pain after 12 and 24 months, respectively. Compared with the lowest tertile, the highest tertile of KFM was significantly related to a lower incidence of frequent knee pain (RR=0.25, 95% CI: 0.08-0.85, P=0.027) in 24 months. In addition, a higher KFM was significantly associated with the lower intensity of incident knee pain after 24 months (β=-1.513; 95% CI: -2.879, -0.147; P=0.030). We also observed trends showing that a higher peak KAM was related to higher risks of developing any (RR=2.48, 95% CI: 0.99-6.20, P=0.053) and frequent (RR=3.82, 95% CI: 0.96-15.1, P=0.057) knee pain in 24 months.ConclusionsA higher sagittal knee moment is associated with a lower risk of knee pain developing in 24 months in older adults.Clinical rehabilitation impactInterventions for promoting sagittal knee moment may be considered in preventative training programs for reducing knee pain among older adults.

Project description:Introduction: The seemingly periodic human gait exhibits stride-to-stride variations as it adapts to the changing task constraints. The optimal movement variability hypothesis (OMVH) states that healthy stride-to-stride variations exhibit "fractality"-a specific temporal structure in consecutive strides that are ordered, stable but also variable, and adaptable. Previous research has primarily focused on a single fractality measure, "monofractality." However, this measure can vary across time; strideto-stride variations can show "multifractality." Greater multifractality in stride-tostride variations would highlight the ability to tune and adjust movements more. Methods: We investigated monofractality and multifractality in a cohort of eight healthy adults during self-paced walking and running trials, both on a treadmill and overground. Footfall data were collected through force-sensitive sensors positioned on their heels and feet. We examined the effects of self-paced walking vs. running and treadmill vs. overground locomotion on the measure of monofractality, α-DFA, in addition to the multifractal spectrum width, W, and the asymmetry in the multifractal spectrum, WAsym, of stride interval time series. Results: While the α-DFA was larger than 0.50 for almost all conditions, α-DFA was higher in running and locomoting overground than walking and locomoting on a treadmill. Similarly, W was greater while locomoting overground than on a treadmill, but an opposite trend indicated that W was greater in walking than running. Larger WAsym values in the negative direction suggest that walking exhibits more variation in the persistence of shorter stride intervals than running. However, the ability to tune and adjust movements does not differ between treadmill and overground, although both exhibit more variation in the persistence of shorter stride intervals. Discussion: Hence, greater heterogeneity in shorter than longer stride intervals contributed to greater multifractality in walking compared to running, indicated by larger negative WAsym values. Our results highlight the need to incorporate multifractal methods to test the predictions of the OMVH.

Project description:Background: Interlimb neural coupling implies that arm swing should be included during gait training to improve rehabilitation outcomes. We previously developed several systems for production of walking with arm swing, but the reaction forces on the foot sole during usage of the systems were not satisfactory and there was potential to improve control system performance. This work aimed to design and technically evaluate a novel system for producing walking with synchronised arm and leg movement and with dynamic force loading on the foot soles. Methods: The robotic system included a passive curved treadmill and a trunk frame, upon which the rigs for the upper and lower limbs were mounted. Ten actuators and servocontrollers with EtherCAT communication protocol controlled the bilateral shoulder, elbow, hip, knee and ankle joints. Impedance control algorithms were developed and ran in an industrial PC. Flexible pressure sensors recorded the plantar forces on the foot soles. The criteria of implementation and responsiveness were used to formally evaluate the technical feasibility of the system. Results: Using impedance algorithms, the system produced synchronous walking with arm swing on the curved treadmill, with mean RMS angular tracking error <2° in the 10 joint profiles. The foot trajectories relative to the hip presented similar shapes to those during normal gait, with mean RMS displacement error <1.5 cm. A force pattern that started at the heel and finished at the forefoot was observed during walking using the system, which was similar to the pattern from overground walking. Conclusion: The robotic system produced walking-like kinematics in the 10 joints and in the foot trajectories. Integrated with the curved treadmill, the system also produced walking-like force patterns on the foot soles. The system is considered feasible as far as implementation and responsiveness are concerned. Future work will focus on improvement of the mechanical system for future clinical application.

Dataset Information

Knee extension moment arm variations relate to mechanical function in walking and running.

Publications

Knee extension moment arm variations relate to mechanical function in walking and running.

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