Catherine A. Stevermer

Gait analysis post anterior cruciate ligament reconstruction: Knee osteoarthritis perspective

Individuals with anterior cruciate ligament (ACL) reconstruction are at increased risk to develop knee osteoarthritis (OA). Gait analysis describing kinetics of the lower extremity during walking and stair use (stair ascent and stair descent) can provide insight to everyday dynamic knee joint loading. In this study, we compared lower extremity gait patterns of those with ACL reconstruction (>1 year) to a control group. Fifteen ACL reconstructed individuals and 17 healthy controls participated in this study. Knee extensor and flexor strength were assessed. Using inverse dynamics, lower extremity moments were calculated during the stance phase of walking and during two steps of stair ascent and descent. Univariate ANOVA was used to test for main effects between (1) injured leg and control group and (2) non-injured leg and control group. Student paired t-tests were used to determine differences between the injured and non-injured leg. Those with ACL reconstruction exhibited reduced initial knee flexion angles during stair descent, reduced knee extension moments during stair descent and stair ascent (second step), and increased hip extension moments during stair ascent (second step) and walking as compared to controls. Knee flexor strength was significantly reduced in the ACL group, but no differences were found in knee extensor strength. No kinematic or kinetic differences were observed between the injured and non-injured leg of the ACL group. Walking and stair ambulation highlight altered joint loading in those with ACL reconstruction surgery. Individuals appeared to compensate for lower knee extension moments by increasing hip extension moments. Furthermore, the load distribution on the articular cartilage is likely shifted as evidenced by reduced knee flexion angles in the ACL reconstructed leg.

The effects of symmetric and asymmetric foot placements on sit-to-stand joint moments

The purpose of this study was to determine the effects of symmetric and asymmetric foot placements on joint moments during sit-to-stand movements. Three symmetric (foot-neutral, foot-back, and foot-intermediate) and three asymmetric foot placements (preferred stagger, nonpreferred stagger, and intermediate stagger) were tested. Standard (46 cm) and low (41 cm) seat heights were chosen to represent an average public seat height and a 10% lower seat height. Using inverse dynamics, maximum ankle plantarflexion, knee extension, hip extension, and hip abduction moments were calculated. Hip extension moments were significantly increased when using foot-neutral as compared to foot-back. Ankle plantarflexion and knee extension moments were significantly increased when a foot was placed in the posterior position as compared to the anterior position for preferred and nonpreferred stagger. Knee extension moments were significantly increased at the low seat height as compared to the standard seat height. When shifting the feet anterior or posterior for symmetric placements during sit-to-stand, the most dramatic effect was an increase in hip extension moments when the feet are shifted anteriorly. Utilizing asymmetric foot placements during sit-to-stand produced increases in ankle plantarflexion and knee extension moments for the posteriorly placed limb, with reductions in the anteriorly placed limb.

The effects of age and type of carrying task on lower extremity kinematics

The purpose of this study was to determine the effects of age, load amount and load symmetry on lower extremity kinematics during carrying tasks. Forty-two participants in four age groups (8–10 years, 12–14 years, 15–17 years and adults) carried loads of 0%, 10% and 20% body weight (BW) in large or small buckets unilaterally and bilaterally. Reflective markers were tracked to determine total joint range of motion and maximum joint angles during the stance phase of walking. Maximum hip extension, hip adduction and hip internal rotation angles were significantly greater for each of the child/adolescent age groups as compared with adults. In addition, maximum hip internal rotation angles significantly increased when carrying a 20% BW load. The observation that the 8–10-year-old age group carried the lightest absolute loads and still displayed the highest maximum hip internal rotation angles suggests a particular necessity in setting carrying guidelines for the youngest children. Statement of Relevance: Bucket-carrying tasks were analysed as a function of age group, load amount and load symmetry. Hip joint rotations significantly increased when carrying 20% BW loads and in children as compared to adults, which suggests a particular necessity in setting carrying guidelines for the youngest age group (8–10 year olds).

Evaluating Doctoral Education in Physical Activity: Role of the American Academy of Kinesiology and Physical Education

This paper summarizes recent events concerning the evaluation of doctoral programs in kinesiology and physical education. An overview is provided of issues related to the evaluation process used by the National Research Council (NRC). The American Academy of Kinesiology and Physical Education (AAKPE) has developed a proposal to have our field included in the upcoming evaluation of doctoral programs conducted by the NRC currently scheduled for 2007. Also described is an overview of the plan by the AAKPE to conduct its own evaluation of doctoral programs in 2005. Finally, a listing of the 62 identified doctoral programs in our field is presented along with some program characteristics.

Muscle activity amplitudes and co-contraction during stair ambulation following anterior cruciate ligament reconstruction.

The purpose of this study was to compare muscle activity amplitudes and co-contraction in those with anterior cruciate ligament (ACL) reconstruction to healthy controls during stair negotiation. Eighteen participants with unilateral ACL reconstruction and 17 healthy controls performed stair ascent and descent while surface electromyography was recorded from knee and hip musculature. During stair ascent, the ACL group displayed higher gluteus maximus activity (1-50% stance, p = 0.02), higher vastus lateralis:biceps femoris co-contraction (51-100% stance, p = 0.01), and higher vastus lateralis:vastus medialis co-contraction (51-100% stance, p = 0.05). During stair descent, the ACL group demonstrated higher gluteus maximus activity (1-50% stance, p = 0.01; 51-100% stance, p < 0.01), lower rectus femoris activity (1-50% stance, p = 0.04), higher semimembranosus activity (1-50% stance, p=0.01), higher gluteus medius activity (51-100% stance, p = 0.01), and higher vastus medialis:semimembranosus co-contraction (1-50% stance, p = 0.02). While the altered muscle activity strategies observed in the ACL group may act to increase joint stability, these strategies may alter joint loading and contribute to post-traumatic knee osteoarthritis often observed in this population. Our results warrant further investigation to determine the longterm effects of altered muscle activity on the knee joint following ACL reconstruction.

Kinematic and Kinetic Indicators of Sit-to-Stand.

Variation in the timing indicators separating sit-to-stand (STS) into movement phases complicates both research comparisons and clinical applications. The purpose of this study was to use kinetic reference standards to identify accurate kinematic and kinetic indicators for STS movement analysis such that consistent indicators might be used for STS from varied initial postures. Healthy adults performed STS using 4 foot placements: foot-neutral, foot-back, right-staggered, and left-staggered. Kinetic and kinematic data were collected from force platforms and an 8-camera video system. Initiation, seat-off, vertical posture, and termination were detected with 5% start and 7.5% end thresholds for changes in kinetic and kinematic STS indicators. Timing differences between kinetic and kinematic indicator time points and the reference vertical seated reaction force end point (seat-off) were determined. Kinematic indicators were compared with selected kinetic indicators using timing differences, statistical similarity, and internal consistency measures. Our results suggest that a single force platform system measuring vertical GRF or a simple camera system to evaluate the shoulder marker position and velocity can accurately and consistently detect STS initiation, seat-off, and vertical posture. In addition, these suggested STS indicators for initiation, seat-off, and vertical posture were not dependent upon foot placement.