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Biomedical subjects

J L McCrory

Publications and source records attributed to J L McCrory.

4 recordsLinked to original sources
PubMed2001

Vertical ground reaction forces: objective measures of gait following hip arthroplasty.

After hip arthroplasty, many patients continue to exhibit abnormal gait patterns. The purpose of this study was to compare the vertical ground reaction forces of a group of 27 individuals who have undergone hip arthroplasty with a group of 35 normal control subjects. Specific force measures were determined from vertical ground reaction forces collected on a treadmill instrumented with two force plates. Symmetry indices were calculated on both groups of subjects. First and second peak forces, loading rate, impulse, and stance time were significantly less, while time to first peak force was significantly greater on the affected leg of the hip arthroplasty subjects when compared to their unaffected leg, or to the control group. The hip arthroplasty group showed greater asymmetry of ground reaction forces than the control group did. Bilateral asymmetric limb loading persists well after unilateral hip replacement surgery. Ground reaction force measures have been shown to be an effective means of quantifying the antalgic gait of hip arthroplasty patients.

Adult↗
PubMed1999

Etiologic factors associated with Achilles tendinitis in runners.

PURPOSE: The purpose of this study was to determine whether relationships exist between selected training, anthropometric, isokinetic muscular strength, and endurance, ground reaction force, and rearfoot movement variables in runners afflicted with Achilles tendinitis. METHODS: Specifically, we examined differences in selected measures between a noninjured cohort of runners (N = 58) and a cohort of injured runners with Achilles tendinitis (N = 31). Isokinetic, kinetic, and kinematic measures were collected using a Cybex II+ isokinetic dynamometer (Medway, MA), AMTI force plate (500 Hz), and Motion Analysis high-speed videography (200 Hz), respectively. Separate discriminant function analyses were performed on each of the five sets of variables to identify the factors that best discriminate between the injured and control groups. RESULTS: Years running, training pace, stretching habits (injured runners were less likely to incorporate stretching into their training routine), touchdown angle, plantar flexion peak torque at 180 degrees x s(-1) and arch index were found to be significant discriminators. CONCLUSION: A combined discriminant analysis using the above mentioned significant variables revealed that plantar flexion peak torque, touchdown angle, and years running were the strongest discriminators between runners afflicted with Achilles tendinitis and runners who had no history of overuse injury.

Achilles Tendon↗
PubMed1999

Evaluation of a Treadmill with Vibration Isolation and Stabilization (TVIS) for use on the International Space Station.

A treadmill with vibration isolation and stabilization designed for the International Space Station (ISS) was evaluated during Shuttle mission STS-81. Three crew members ran and walked on the device, which floats freely in zero gravity. For the majority of the more than 2 hours of locomotion studied, the treadmill showed peak to peak linear and angular displacements of less than 2.5 cm and 2.5 degrees, respectively. Vibration transmitted to the vehicle was within the microgravity allocation limits that are defined for the ISS. Refinements to the treadmill and harness system are discussed. This approach to treadmill design offers the possibility of generating 1G-like loads on the lower extremities while preserving the microgravity environment of the ISS for structural safety and vibration free experimental conditions.

Equipment Design↗