Effect of Laterally Wedged Insoles on the External Knee Adduction Moment across Different Reference Frames

Gait Characteristics Associated with Walking Speed in Postoperative Patients with Adult Spinal Deformity Extracted by Machine Learning

PURPOSE

Patients with adult spinal deformity (ASD) are unable to walk faster even after spinal fixation. Gait rehabilitation that focuses on movements associated with reduced speed may help improve gait function. This study aimed to identify the gait characteristics associated with walking velocity in postoperative patients with ASD.

METHODS

Three-dimensional gait analysis was performed in 62 postoperative patients with ASD and 105 healthy volunteers. A dimensionality reduction method, based on data from the healthy cohort, was applied to 194 gait characteristics of the patients. Then, the Markov Chain Monte Carlo method sampled the gait characteristics related to speed, and k-means clustering categorized the gait patterns. The relationships between the extracted gait characteristics and velocity were assessed using multiple regression analysis within each cluster.

RESULTS

Hip sagittal angle and moment (β = - 0.47 to 0.42) were significantly associated with postoperative velocity in all the patients (R2 = 0.834). Two clusters were identified, and hip sagittal moments at contralateral contact and toe-off (β = - 0.58 and 0.68, respectively) were associated with velocity in the group that walked faster (R2 = 0.634). Maximum ankle plantarflexion moment and hip flexion power (β = 0.53 and 0.33, respectively) were associated with velocity in the group that walked slowly (R2 = 0.448).

CONCLUSION

Larger hip joint movement may play a crucial role in enhancing gait velocity because the spinal fixation limits spino-pelvic movement. To improve gait speed, postoperative older adults with ASD who walk slowly may require new rehabilitation strategies that exert more ankle plantarflexion moment and develop an adequate stance phase to facilitate hip extension.

Bilateral waveform analysis of gait biomechanics presurgery to 12 months following ACL reconstruction compared to controls

The purpose of this study was to compare gait biomechanics between limbs and to matched uninjured controls (i.e., sex, age, and body mass index) preoperatively and at 2, 4, 6, and 12 months following primary unilateral anterior cruciate ligament reconstruction (ACLR). Functional mixed effects models were used to identify differences in gait biomechanics throughout the stance phase between the a) ACLR limb and uninvolved limb, b) ACLR limb and controls, and c) uninvolved limb and controls. Compared with the uninvolved limb, the ACLR limb demonstrated lesser knee extension moment (KEM; within 8-37% range of stance) during early stance as well as lesser knee flexion moment (KFM; 45-84%) and greater knee flexion angle (KFA; 43-90%) during mid- to late stance at all timepoints. Compared with controls, the ACLR limb demonstrated lesser vertical ground reaction force (vGRF; 5-26%), lesser KEM (7-47%), and lesser knee adduction moment (KAM; 12-35%) during early stance as well as greater vGRF (39-63%) and greater KFA (34-95%) during mid- to late stance at all timepoints. Compared with controls, the uninvolved limb demonstrated lesser KFA (1-56%) and lesser KEM (12-54%) during early to mid-stance at all timepoints. While gait becomes more symmetrical over the first 12 months post-ACLR, the ACLR and uninvolved limbs both demonstrate persistent aberrant gait biomechanics compared to controls. Biomechanical waveforms throughout stance can be generally described as less dynamic following ACL injury and ACLR compared with uninjured controls.

Stair-descent phenotypes in community-dwelling older adults determined using high-level balance tasks

BACKGROUND

Falls on stairs are a major cause of severe injuries among older adults, with stair descent posing significantly greater risks than ascent. Variations in stair descent phenotypes may reflect differences in physical function and biomechanical stability, and their identification may prevent falls.

AIMS

This study aims to classify stair descent phenotypes in older adults and investigate the biomechanical and physical functional differences between these phenotypes using hierarchical cluster analysis.

METHODS

Eighty-two older adults participated in this study. Stair descent was measured using a three-dimensional motion analysis system. Physical function was assessed using measures of muscle strength, walking speed, the Timed Up and Go Test (TUG), and the Community Balance and Mobility Scale (CB&M).

RESULTS

Hierarchical cluster analysis was performed on kinematic data obtained during stair descent. Three phenotypes were identified: neutral (N-type; 24%), extension (E-type; 52%), and rotation (R-type; 23%). There were no significant differences in lower limb muscle strength or walking speed among the different types, and TUG scores showed no differences in terms of mobility or balance abilities. However, CB&M scores were significantly lower for E-type and R-type compared to N-type. Sub-analyses revealed that while there were no differences in the mobility factor of CB&M between E-type and R-type, the strength factors were significantly lower compared to those for N-type.

DISCUSSION

These results suggest that E-type and R-type stair-descent patterns may be influenced by declines in standing balance ability and muscle strength.

CONCLUSIONS

These findings may inform fall-prevention training programs related to stair descent among older adults.

Can foot orthoses impose different gait features based on geometrical design in healthy subjects? A systematic review and meta-analysis

OBJECTIVE

Foot orthoses (FOs) are popular treatment to alleviate several abnormalities of lower extremity. FO designs might alter lower extremity biomechanics differently, but the association is not yet known. This review aimed to evaluate how different FO designs, namely FO with medial posting, lateral posting, arch support, or arch & heel support, change lower limb kinematics and kinetics during walking.

LITERATURE SURVEY

Electronic database search were conducted from inception to March 2019, and 25 papers passed the inclusion criteria. Two independent reviewers checked the quality using a modified Downs and Black checklist (73.7±5.5%) and a biomechanical quality checklist (71.4±17.1%). Effect sizes for differences between with- and without- FO walking were calculated, and meta-analysis was performed whenever at least two studies reported the same variable.

RESULTS

Medial posting reduced peak ankle eversion moment. Lateral posting brought about higher peak ankle dorsiflexion and peak ankle eversion for kinematics, as well as higher peak ankle abduction moment, lower peak knee adduction moment, and higher peak mediolateral ground reaction force (GRF) for kinetics. FOs with either arch support or arch & heel support tended to decrease vertical ground reaction force, but it was not significant.

CONCLUSION

The findings of this review reveal that medial or lateral posting work efficiently to change foot and knee kinematics and kinetics. However, the impact force is just slightly decreased by arch-supported and heel supported FOs. Due to the small number of available studies, and heterogeneity in meta-analysis findings, further research with more standardized biomechanical approach are required.

Impaired Motor Skill Acquisition Using Mirror Visual Feedback Improved by Transcranial Direct Current Stimulation (tDCS) in Patients With Parkinson's Disease

Recent non-invasive brain stimulation techniques in combination with motor training can enhance neuroplasticity and learning. It is reasonable to assume that such neuroplasticity-based interventions constitute a useful rehabilitative tool for patients with Parkinson's Disease (PD). Regarding motor skill training, many kinds of tasks that do not involve real motor movements have been applied to PD patients. The purpose of this study is to elucidate whether motor skill training using mirror visual feedback (MVF) is useful to patients with PD in order to improve untrained hand performance dependent on the time course of training; and whether MVF combined with anodal transcranial direct current stimulation (tDCS) over primary motor cortex (M1) causes an additional effect based on increased motor cortical excitability. Eighteen right-handed patients with PD in the off-medication state and 10 age-matched healthy subjects (HS) performed four sessions of right-hand ball rotation using MVF (intervention) on two separate days, 1 week apart (day 1 and day 2). HS subjects received only sham stimulation. The intervention included four sessions of motor-skill training using MVF for 20 min comprised of four sets of training for 30 s each. PD patients were randomly divided into two intervention groups without or with anodal tDCS over the right M1 contralateral to the untrained hand. As the behavior evaluation, the number of ball rotations of the left hand was counted before (pre) and immediately after (post) intervention on both days (pre day 1, post day 1, pre day 2, and post day 2). Motor evoked potential (MEP), input-output function, and cortical silent period were recorded to evaluate the motor cortical excitatory and inhibitory system in M1 pre day 1 and post day 2. The number of ball rotations of the left hand and the facilitation of MEP by intervention were significantly impaired in patients with PD compared to HS. In contrast, if anodal tDCS was applied to right M1 of patients with PD, the number of ball rotations in accordance with I-O function at 150% intensity was significantly increased after day 1 and retained until day 2. This finding may help provide a new strategy for neurorehabilitation improving task-specific motor memory without real motor movements in PD.

Mechanical effects of medial and lateral wedged orthoses during running

OBJECTIVE

The aim of the current investigation was to examine the effects of orthoses with 5° medial and lateral wedges on knee joint kinetics during the stance phase of running.

DESIGN

Repeated measures.

SETTING

Laboratory.

PARTICIPANTS

Twelve recreational runners.

OUTCOME MEASUREMENTS

Twelve male participants ran over a force platform at 4.0 m/s in three different conditions (medial orthotic, lateral orthotic and no-orthotic). Lower limb kinematics were collected using an 8-camera motion capture system allowing knee kinetics to be quantified using a musculoskeletal modelling approach. Differences in knee joint kinetics between orthotic conditions were examined using one-way repeated measures ANOVA.

RESULTS

The results showed that peak patellofemoral force was significantly increased in the medial (31.81 N/kg) and lateral (31.29 N/kg) wedged orthoses, in comparison to the no-orthotic (29.61 N/kg) condition. In addition, the peak knee adduction moment was significantly increased in the medial (1.10 Nm/kg) orthoses, in comparison to the lateral (0.87 Nm/kg) condition.

CONCLUSIONS

The results from this study indicate that lateral orthoses may be effective in attenuating runners risk from medial tibiofemoral compartment OA, but that wedged orthoses may enhance their risk from patellofemoral pain.

Verifying the equivalence of representations of the knee joint moment vector from a drop vertical jump task

Biomechanics software programs, such as Visual3D, Nexus, Cortex, and OpenSim, have the capability of generating several distinct component representations for joint moments and forces from motion capture data. These representations include those for orthonormal proximal and distal coordinate systems and a non-orthogonal joint coordinate system. In this article, a method is presented to address the challenging problem of evaluating and verifying the equivalence of these representations. The method accommodates the difficulty that there are two possible sets of non-orthogonal basis vectors that can be used to express a vector in the joint coordinate system and is illuminated using motion capture data from a drop vertical jump task.