Children with Cerebral Palsy Have Similar Walking and Running Quality Assessed by an Overall Kinematic Index.

Running ability is critical to maintaining activity participation with peers. Children and adolescents with cerebral palsy (CP) are often stated to run better than they walk, but running is not often quantitatively measured. The purpose of this study was to utilize overall gait deviation indices to determine if children with diplegic CP run closer to typically developing children than they walk.

Multisegment Foot Kinematic and Kinetic Compensations in Level and Uphill Walking Following Tibiotalar Arthrodesis.

Background: Foot and ankle movement alterations following ankle arthrodesis are still not well understood, particularly those that might contribute to the documented increase in adjacent joint arthritis. Generalized tarsal hypermobility has long been postulated, but not confirmed in gait or functional movements. The purpose of this study was to more thoroughly evaluate compensation mechanisms used by arthrodesis patients during level and uphill gait through a variety of measurement modalities and a detailed breakdown of gait phases.

Comparison of hierarchical and six degrees-of-freedom marker sets in analyzing gait kinematics.

The objective of this study was to determine how marker spacing, noise, and joint translations affect joint angle calculations using both a hierarchical and a six degrees-of-freedom (6DoF) marker set. A simple two-segment model demonstrates that a hierarchical marker set produces biased joint rotation estimates when sagittal joint translations occur whereas a 6DoF marker set mitigates these bias errors with precision improving with increased marker spacing. These effects were evident in gait simulations where the 6DoF marker set was shown to be more accurate at tracking axial rotation angles at the hip, knee, and ankle.

Cervical spine motion during football equipment-removal protocols: a challenge to the all-or-nothing endeavor.

Context: The National Athletic Trainers' Association position statement on acute management of the cervical spine-injured athlete recommended the all-or-nothing endeavor, which involves removing or not removing both helmet and shoulder pads, from equipment-laden American football and ice hockey athletes. However, in supporting research, investigators have not considered alternative protocols.

Objective: To measure cervical spine movement (head relative to sternum) produced when certified athletic trainers (ATs) use the all-or-nothing endeavor and to compare these findings with the movement produced using an alternative pack-and-fill protocol, which involves packing the area under and around the cervical neck and head with rolled towels.

Analysis of a kinetic multi-segment foot model. Part I: Model repeatability and kinematic validity.

Kinematic multi-segment foot models are still evolving, but have seen increased use in clinical and research settings. The addition of kinetics may increase knowledge of foot and ankle function as well as influence multi-segment foot model evolution; however, previous kinetic models are too complex for clinical use. In this study we present a three-segment kinetic foot model and thorough evaluation of model performance during normal gait.

Analysis of a kinetic multi-segment foot model part II: kinetics and clinical implications.

Kinematic multi-segment foot models have seen increased use in clinical and research settings, but the addition of kinetics has been limited and hampered by measurement limitations and modeling assumptions. In this second of two companion papers, we complete the presentation and analysis of a three segment kinetic foot model by incorporating kinetic parameters and calculating joint moments and powers. The model was tested on 17 pediatric subjects (ages 7-18 years) during normal gait.

Measured and estimated ground reaction forces for multi-segment foot models.

Accurate measurement of ground reaction forces under discrete areas of the foot is important in the development of more advanced foot models, which can improve our understanding of foot and ankle function. To overcome current equipment limitations, a few investigators have proposed combining a pressure mat with a single force platform and using a proportionality assumption to estimate subarea shear forces and free moments. In this study, two adjacent force platforms were used to evaluate the accuracy of the proportionality assumption on a three segment foot model during normal gait.

Implications of using hierarchical and six degree-of-freedom models for normal gait analyses.

Hierarchical biomechanical models (conventional gait model, CGM) are attractive because of simple data collection demands, yet they are susceptible to errors that are theoretically better controlled using six degree-of-freedom models that track body segments independently (OPT1). We wished to compare gait variables obtained with these models. Twenty-five normal children walked while wearing a hybrid marker configuration, permitting identical strides to be analyzed using CGM and OPT1.

Performance of an inverted pendulum model directly applied to normal human gait.

Background: In clinical gait analysis, we strive to understand contributions to body support and propulsion as this forms a basis for treatment selection, yet the relative importance of gravitational forces and joint powers can be controversial even for normal gait. We hypothesized that an inverted pendulum model, propelled only by gravity, would be inadequate to predict velocities and ground reaction forces during gait.

Methods: Unlike previous ballistic and passive dynamic walking studies, we directly compared model predictions to gait data for 24 normal children.

Novel biomechanics demonstrate gait dysfunction due to hamstring tightness.

Background: Children with cerebral palsy and hamstring tightness often demonstrate limited terminal swing knee extension. The conventional clinical measure of popliteal angle describes static hamstring tightness, but is not consistent with dynamic limitation. We hypothesize hamstring tightness, determined via modification of the conventional popliteal angle measure, is directly related to decreased terminal swing knee extension in children with cerebral palsy and normal magnitude knee flexion moments.

Impact of mediolateral segmentation on a multi-segment foot model.

MacWilliams et al. report their progress on a multi-segment foot model, including mediolateral segmentation, from which they calculate kinematics and kinetics [MacWilliams BA, Cowley M, Nicholson DE. Foot kinematics and kinetics during adolescent gait.

Challenges in hip joint modeling for a patient with proximal femoral focal deficiency.

We were presented with a technical challenge driven by a clinical need. A patient with proximal femoral focal deficiency required gait analysis, but our typical biomechanical model [Vicon Clinical Manager (VCM)] would not have correctly identified his abnormal right hip center (RHIP). His underdeveloped right femur was fused to his ileum, his anatomical knee functioned as his right hip, and an above-knee prosthesis provided functional knee and ankle joints.