Lower Limb Biomechanics in Individuals With Knee Osteoarthritis Before and After Total Knee Arthroplasty Surgery

We investigated the biomechanical changes that occur in the lower limb following total knee arthroplasty (TKA). Lower limb joint kinematics and kinetics were evaluated in 32 patients before and 12 months following TKA and 28 age-matched controls. Analysis of variance with Bonferroni-adjusted post-hoc tests showed no significant changes in knee joint kinematics and kinetics following TKA despite significant improvements in pain and function. Significant increases in peak ankle plantarflexion and dorsiflexion moments and ankle power generation were observed which may be a compensatory response to impaired knee function to allow sufficient power generation for propulsion. Differences in knee gait parameters may arise as a result of the presence of osteoarthritis and mechanical changes associated with TKA as well as retention of the pre-surgery gait pattern.     

Does the Anterior Approach for THA Provide Closer-To-Normal Lower-Limb Motion?

The purpose of this study was to compare the muscle-sparing anterior approach for total hip arthroplasty to a traditional lateral approach using 3D motion analysis. Kinematics and kinetics of walking were obtained for 40 patients (20 anterior and 20 lateral) and 20 control participants. Participants were assessed six to twelve months postoperatively. It was hypothesized that the anterior group would have closer-to-normal range of motion, moments, and powers than the lateral group. Both surgical groups had gait anomalies, such as significantly lower peak hip abduction moments. It is therefore thought that other variables such as preoperative gait adaptations, trauma from the surgery, or postoperative protection mechanisms for avoiding loading the prosthesis might be more influential factors than surgical approach when determining function after surgery.     

Kinematic patterns for hindlimb obstacle avoidance during sheep locomotion

ABSTRACT

Functional recovery following general nerve reconstruction is often associated with poor results. Comparing to rat and mice experimental studies, there are much fewer investigations on nerve regeneration and repair in the sheep, and there are no studies on this subject using gait analysis in the sheep model as an assessment tool. Additionally, this is the first study evaluating obstacle negotiation and the compensatory strategies that take place at each joint in response to the obstacle during locomotion in the sheep model. This study aims to get kinematic data to serve as a template for an objective assessment of the ankle joint motion in future studies of common peroneal nerve (CP) injury and repair in the ovine model. Our results show that a moderately high obstacle set to 10% of the sheep’s hindlimb length was associated to several spatial and temporal strategies in order to increase hoof height during obstacle negotiating. Sheep efficiently cleared an obstacle by increasing knee, ankle and metatarsophalangeal flexion during swing, whereas the hip joint is not affected. This study establishes the bounds of normal motion in the neurologically intact hindlimb when approached and cleared an obstacle and provides baseline data for further studies of peripheral nerve research in the ovine model.     

Head‐pelvis coupling is increased during turning in patients with Parkinson's disease and freezing of gait

Turning is the most important trigger for freezing of gait (FOG). The aim of this study was to investigate the relationship between impaired head‐pelvis rotation during turning and FOG. Head, trunk, and pelvic rotation were measured at onset and throughout a 180‐degree turn in 13 freezers and 14 nonfreezers (OFF medication). We also studied 14 controls at preferred and slow speed to investigate the influence of turn velocity on axial rotation. Location and duration of FOG episodes were defined during the turn. At turning onset, head rotation preceded thorax and pelvic rotation in all groups, but this craniocaudal sequence disappeared when FOG occurred. Maximum head‐pelvis separation was significantly greater in controls, compared to freezers and nonfreezers (35.4 versus 25.7 and 27.3 degrees; P < 0.01), but this finding was speed dependent. Timing of maximum head‐pelvis separation was delayed in freezers, compared to nonfreezers and controls, irrespective of turn velocity. This delay was correlated with increased neck rigidity (R = 0.62; P = 0.02) and worsened during FOG trials. FOG occurred more often at the end of the turn, when difference in rotation velocity between head and pelvis was greatest. Even after controlling for speed and disease severity, turning in freezers was characterized by delayed head rotation and a closer coupling between head and pelvis, especially in turns where FOG occurred. These changes may be attributed to delayed preparation for the change in walking direction and, as such, contribute to FOG. © 2013 Movement Disorder Society     

Driving and off‐road impairments underlying failure on road testing in Parkinson's disease

Parkinson's disease (PD) affects driving ability. We aimed to determine the most critical impairments in specific road skills and in clinical characteristics leading to failure on a road test in PD. In this cross‐sectional study, certified driving assessment experts evaluated specific driving skills in 104 active, licensed drivers with PD using a standardized, on‐road checklist and issued a global decision of pass/fail. Participants also completed an off‐road evaluation assessing demographic features, disease characteristics, motor function, vision, and cognition. The most important driving skills and off‐road predictors of the pass/fail outcome were identified using multivariate stepwise regression analyses. Eighty‐six (65%) passed and 36 (35%) failed the on‐road driving evaluation. Persons who failed performed worse on all on‐road items. When adjusted for age and gender, poor performances on lateral positioning at low speed, speed adaptations at high speed, and left turning maneuvers yielded the best model that determined the pass/fail decision (R² = 0.56). The fail group performed poorer on all motor, visual, and cognitive tests. Measures of visual scanning, motor severity, PD subtype, visual acuity, executive functions, and divided attention were independent predictors of pass/fail decisions in the multivariate model (R² = 0.60). Our study demonstrated that failure on a road test in PD is determined by impairments in specific driving skills and associated with deficits in motor, visual, executive, and visuospatial functions. These findings point to specific driving and off‐road impairments that can be targeted in multimodal rehabilitation programs for drivers with PD. © 2013 International Parkinson and Movement Disorder Society     

Fall risk and gait in Parkinson's disease: The role of the LRRK2 G2019S mutation

Patients with Parkinson's disease (PD) who carry the G2019S mutation (a glycine to serine substitution at amino acid 2019) in the leucine‐rich repeat kinase 2 (LRRK2) gene are generally believed to be clinically indistinguishable from patients with sporadic PD. There are, however, conflicting reports on the relationship between the mutation and the motor phenotype. We quantitatively compared gait and mobility in patients with PD carriers of the G2019S mutation to non‐carrier patients with PD to better understand the genotype‐phenotype relationship. Fifty patients with PD carriers of the G2019S LRRK2 mutation and 50 age, disease duration, and disease severity matched PD non‐carriers were studied. An accelerometer quantified gait under three walking conditions: usual‐walking, dual‐tasking, and fast‐walking. The Unified Parkinson's Disease Rating Scale classified patients into PD sub‐types and the Timed Up and Go quantified mobility and fall risk. In all three walking conditions, gait variability was larger and the walking pattern was less consistent among the PD mutation carriers (P < 0.016). The PD carriers also took longer to complete the Timed Up and Go (P = 0.011) and were more likely to report having fallen in the previous year (P = 0.018). 64% of the PD carriers were classified as belonging to the postural‐instability‐gait‐difficulty (PIGD) sub‐type compared to only 17% of the PD non‐carriers (P < 0.0001). Among patients with PD, the G2019S mutation in the LRRK2 gene is apparently associated with increased gait variability, an increased fall risk, and the PIGD sub‐type. Therapeutic approach specifically designed to delay gait disturbances and falls may be justified in patients who carry the G2019S mutation. © 2013 International Parkinson and Movement Disorder Society     

The conventional gait model,an open-source implementation that reproduces the past but prepares for the future

BackgroundThe Conventional Gait Model (CGM), known by a variety of different names, is widely used in clinical gait analysis. We present pyCGM2, an open-source implementation of the CGM with two versions. The first, CGM1.0, is a clone of Vicon Plug In Gait (PiG) with all its variants. CGM1.0 provides a platform to test the effect of modifications to the CGM on data collected and processed retrospectively or to provide backward compatibility.The second version, CGM1.1, offers some practical modifications and includes three well documented improvements.Research questionHow do improvements of the conventional gait model affect joint kinematics and kinetics?MethodThe practical modifications include the possibility to use a medial knee epicondyle marker, during static calibration only, to define the medio-lateral axis of the femur in place of the knee alignment device. The three improvements correspond to the change of pelvis angle decomposition sequence, the adoption of a single tibia coordinate system, and the default decomposition of the joint moments in the joint coordinate system. We validated the outputs of version CGM1.0 against Vicon-PiG, and estimated the effect of the modifications included in version CGM1.1 using gait data collected in 16 healthy participants.ResultsKinematics and kinetics of CGM1.0 were superimposed with that of Vicon-PiG, with root mean square differences less than 0.04° for kinematics and less than 0.05 N.m.kg-1 for kinetics.SignificanceThe differences between the CGM1.1 and CGM1.0 were minimal in the healthy participant cohort but we discussed the expected difference in participants with different gait pathologies.We hope that the pyCGM2 will facilitate the systematic testing and the use of improved processing methods for the conventional gait model.     

社区老年人双重任务行走步态特征与跌倒的关系研究

目的探索社区老年人双重任务行走步态参数与过去一年跌倒史的关系。方法方便抽取135名社区老年人,根据过去一年有无跌倒史分为跌倒组(23名)与未跌倒组(112名)。运用问卷和便携式步态分析仪分别采集老年人一般信息、健康资料与10m双重任务行走步态参数。结果两组居住方式、家庭人均月收入及TUGT比较,差异有统计学意义(均P0.05);两组单脚支撑时间、单脚支撑时间/双脚支撑时间、步幅持续时间、周期时间、地面冲击、落脚强度、离地时脚的角度、速度与步频比较,差异有统计学意义(P0.05,P0.01)。结论双重任务行走时步态性能较差的社区老年人易发生跌倒。政府应加强公共活动场所的安全基础建设,鼓励老年人加强腿部肌肉锻炼和双重任务训练;医务人员应重视对老年患者步态的评估和功能锻炼,提高老年人行走能力,以预防跌倒发生。     

Dynamics of quadrupedal locomotion of monkeys: implications for central control

We characterized the three-dimensional kinematics and dynamics of quadrupedal gait of young adult rhesus and cynomolgus monkeys while they walked with diagonal and lateral gaits at 0.4–1.0 m/s on a treadmill. Rigid bodies on the wrist, ankle, and back were monitored by an optical motion detection system (Optotrak). Kinematic data could be normalized using characteristic stride length, reducing variance due to different gait styles, to emphasize common characteristics of swing and stance parameters among animals. Mean swing phase durations fell as walking speed increased, but the swing phase durations increased at each walking velocity as a linear function of increases in amplitude, thereby following a main sequence relationship. The phase plane trajectories of the swing phases, i.e., plots of the relation of the rising and falling limb velocity to limb position in the sagittal (X–Z) plane, had unique dynamic characteristics. Trajectories were separable at each walking velocity and increases in swing amplitude were linearly related to peak swing velocities, thus comprising main sequences. We infer that the swing phase dynamics are set by central neural mechanisms at the onset of the swing phases according to the intended amplitude, which in turn is based on the walking velocity in the stance phases. From the many dynamic similarities between swing phases and rapid eye movements, we further suggest that the swing phases may be generated by neural mechanisms similar to those that produce saccades and quick phases of nystagmus from a signal related to sensed or desired walking velocity. Grants: This work was supported by National Institute of Health Grants EY11812, EY04148, DC05204, and EY01867.