Gross Motor Function Classification System and outcome tools for assessing ambulatory cerebral palsy: a multicenter study.

The relationships between different levels of severity of ambulatory cerebral palsy, defined by the Gross Motor Function Classification System (GMFCS), and several pediatric outcome instruments were examined. Data from the Gross Motor Function Measure (GMFM), Pediatric Orthopaedic Data Collection Instrument (PODCI), temporal-spatial gait parameters, and oxygen cost were collected from six sites. The sample size for each assessment tool ranged from 226 to 1047 participants. There were significant differences among GMFCS levels I, II, and III for many of the outcome tools assessed in this study. Strong correlations were seen between GMFCS level and each of the GMFM sections D and E scores, the PODCI measures of Transfer and Mobility, and Sports and Physical Function, Gait Velocity, and Oxygen Cost. Correlations among tools demonstrated that the GMFM sections D and E scores correlated with the largest number of other tools. Logistic regression showed GMFM section E score to be a significant predictor of GMFCS level. GMFM section E score can be used to predict GMFCS level relatively accurately (76.6%). Study data indicate that the assessed outcome tools can distinguish between children with different GMFCS levels. This study establishes justification for using the GMFCS as a classification system in clinical studies.

Kinematic and kinetic analysis of running in children with cerebral palsy.

Computer-based analysis of gait was used to study walking and running in 19 children with spastic-diplegic cerebral palsy (CP) and 15 healthy control children. Temporospatial parameters, kinematic and kinetic data were compared and contrasted between groups for both types of gait. The majority of children with diplegic CP, who are independent ambulators, are able to run. These children increase their velocity by increasing their cadence, a mechanism that is distinct (and presumably less energy efficient) from that used by healthy children. Sagittal-plane kinematic and kinetic profiles at the ankle in children with CP were more similar to normal profiles in running than in walking, suggesting that the primary deviations at the ankle associated with CP are better tolerated at greater velocities. Relative power analysis showed that, like healthy children, those with CP depend more upon the proximal musculature about the hip for power generation as the velocity of gait increases. Children with CP achieve energy transfer between adjacent joints during walking and running in a manner comparable to unaffected children. Running is an important activity for children and should be considered in the functional assessment of those with CP.

A dynamic biomechanical analysis of the etiology of adolescent tibia vara.

Biomechanical overload of the proximal tibial physis due to static varus alignment and excessive body weight has been implicated in the etiology of infantile tibia vara. Whether a similar pathophysiologic process applies to adolescent tibia vara is controversial, with poor consensus concerning the nature and significance of static knee alignment early in the course of the disease. This study examines the hypothesis that dynamic gait deviations to compensate for increased thigh girth associated with obesity (fat-thigh gait) could result in increased loading of the medial compartment of the knee during the gait cycle. Three-dimensional motion analysis was used to identify the kinematic/kinetic profile associated with fat-thigh gait. Gait deviations identified were dynamic stance-limb knee varus, increased stance-limb knee rotation, and swing-limb circumduction. Pathologic compressive forces were generated in an anthropometric model by using recorded fat-thigh gait deviations and clinically appropriate excessive body weight. This analysis supports the clinical observation that underlying static varus malalignment of the knee is not a prerequisite for the development of adolescent tibia vara and illustrates the significance of dynamic gait deviations when considering knee-joint loading.

A biomechanical and clinical evaluation of a patellofemoral knee brace.

A clinical and biomechanical evaluation of a patellofemoral knee brace was conducted to determine subjectively and objectively if the brace was effective in controlling knee motion and relieving patellofemoral pain symptoms. The subjective results indicated that the patellofemoral brace was able to significantly improve the level of perceived knee stability and decrease the level of pain experienced by all the subjects during their daily living and athletic activities. The objective results showed that the patellofemoral brace had no effect on knee flexion angle during gait or level walking, stair ascent, or stair descent for 2 groups of subjects (patellofemoral patients and controls). Joint pain and stability are affected by factors other than knee flexion angle.

The prediction of metabolic energy expenditure during gait from mechanical energy of the limb: a preliminary study.

Measurements of metabolic energy consumption and free-walking velocity were recorded for four persons with trans-femoral amputation with variations of prosthesis mass and mass distribution. Hot-film anemometers, rate gyroscopes, and a force platform were used to measure prosthetic limb segment velocities and ground reaction forces. Metabolic energy consumption for the nine configurations of mass and mass distribution averaged 1.177 cal/kg/m with a standard deviation of +/- 0.052 cal/kg/m. Two measures of mechanical work of the amputated extremity, one based on power developed across joints (W1) and the other based on changes in energy of the body segments (W2), were computed to be 0.162 +/- 0.014 and 0.175 +/- 0.025 cal/kg/m, respectively. A linear regression model led to rejections of both W1 and W2 as predictors of metabolic energy expenditure of the amputee at a significance level of 0.05.

Ankle weight effect on gait: orthotic implications.

Oxygen consumption during ambulation was measured in 10 normal subjects wearing ankle weights of 0.91 kg, 1.82 kg, and 2.73 kg, either on the right ankle or bilaterally. Subjects walked at self-selected speeds and oxygen consumption was measured over 1-minute intervals during steady-state walking. Oxygen consumption per unit distance and oxygen consumption rate demonstrated significant positive linear correlations with added weight (P = .001, P = 0.007, respectively). Velocity demonstrated a significant decrease when correlated with added weight (P = 0.03). Multiple regression analysis was used to relate these measures of oxygen consumption rates to velocity, age, and added weight, yielding predictive relationships. Based on these results, the weight of orthoses should be minimized in order to maximize walking velocity and minimize oxygen consumption per unit distance. The advantage of a light-weight, molded plastic ankle-foot orthosis (AFO) over heavier AFO designs is demonstrated by this study.