This article describes and explains the moment arm vector (MAV) concept, uses the concept for the quantitative classification of hip muscles according to action, and applies the findings to selected clinical problems. A three-dimensional, straight-line model of hip musculature was used. Measurements made on a matched, dry bone specimen provided muscle attachment point location data for the model. Straight lines of muscle action between attachment sites were simulated for a variety of hip configurations during simple hip motions in three principal anatomical planes. We used the MAV concept to identify the three contributions of a muscle (flexion-extension, abduction-adduction, and internal-external rotation) tending to rotate the thigh segment relative to the pelvis. Muscles were classified according to their action or turning effect at 0, 40, and 90 degrees of hip flexion. Certain muscles exhibited significant changes in their action during these simple motions. Model results were verified using an articulated, dry bone specimen with elastic strings stretched between muscle attachment sites. Based on this geometrical model, a "pathological posture" of hip flexion, adduction, and internal rotation was identified, which is a posture prevalent in spastic, brain damaged patients.

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This study was undertaken to determine the onset, duration, and degree of electromyographic activity in the anterior, middle, and posterior segments of the gluteus medius muscle during functional activities. Fine wire electrodes were inserted into each muscle segment. After a triaxial hip electrogoniometer was applied, each of the 10 subjects performed the activities of walking, crawling, stair ascending and descending, shoetying, sitting, and single limb-standing with forward learning. Raw electromyographic records evaluated on the basis of on-off activity provided results showing that the onset, duration, and degree of activity of the three segments was similar for some activities. Results also established that asynchronous activity occurred for selected functional activities, thereby justifying a three-segment conceptual model of the gluteus medius muscle.

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Clinical practice databases are frequently used to assess outcomes in various medical specialties. Formulating a computerized physical therapy medical record requires standardization of clinical assessments among the users. The purpose of this article is to describe an acute care physical therapy database system that emphasizes high-quality measures of function. The logic underlying the development of a physical therapy computerized medical record is described. Selected uses of the database are demonstrated by projects that assess data quality, generate clinical hypotheses, manage clinical data, develop clinical measures, and generate pilot data on patient variability. Patients seen in physical therapy for total joint replacement, pain, and decreased ambulation were studied to demonstrate some of the present capabilities of the database. Clinical practice databases contribute to the overall research mission, provided the data are of high quality. The use of databases in conjunction with randomized clinical trials may serve an important role in determining effective physical therapy interventions to reduce disability.