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Biomedical subjects

W A Hodge

Publications and source records attributed to W A Hodge.

25 records · Page 2Linked to original sources
PubMed1991

Influence of age on dynamics of rising from a chair.

This article describes the sit-to-stand movement in nine healthy elderly adults, ages 61 to 74 years, and compares peak joint angles, torques, and velocities of 11 body segments with data collected from nine young women, ages 25 to 36 years. The subjects in this study rose from a chair under a controlled protocol. An optoelectronic system, two force plates, and two computers were used for data collection and processing. The data are described in relationship to three phases of the task previously described for the young subjects' data. Percentages of difference were calculated for the torques and the velocities. Independent t tests were conducted on maximum angles achieved and total joint excursions. Consistency between groups was demonstrated in the duration of each phase, as well as the body kinematics and kinetics occurring within each phase. There was little difference in maximum torques or velocities. Maximum angles of head-to-trunk extension, head-to-ground flexion, head-to-trunk excursion, and trunk-to-pelvis flexion were significantly different between groups. The differences in head position demonstrated between these two groups may have clinical implications for loss of balance during this task in older patients.

Adult↗
PubMed1991

Prevention of deep vein thrombosis after total knee arthroplasty. Coumadin versus pneumatic calf compression.

The rate of deep vein thrombosis (DVT) after total knee arthroplasty (TKA) without prophylaxis has been reported as high as 84%. Coumadin anticoagulation and pneumatic calf compression (PCC) boots are two current therapies that have been thought to be effective in reducing this high rate of DVT. To investigate these two methods, a nonrandomized prospective study was designed. The first group involved treating 48 consecutive knee arthroplasties with a regimen of coumadin anticoagulation. The second group involved 81 consecutive knee arthroplasties treated with sequential PCC boots. Bilateral lower extremity venography was performed between the eighth and tenth hospital postoperative days. The overall incidence of DVT in the coumadin group was 33%, with 29% having calf thrombi and 6% having thigh thrombi. The overall incidence of DVT in the boot group was 31%, with 27% having calf thrombi and 6% having thigh thrombi. In both groups, there were no treatment-related complications. Cost analysis of the administration of each type of therapy showed coumadin to be approximately 50% more expensive than PCC boots. Although coumadin and PCC boot therapy are safe and effective in reducing the incidence of DVT after TKA, there are economic factors that make the latter a more favorable option.

Female↗
PubMed1990

Modelling of the biomechanics of posture and balance.

A technique for studying the relationship of posture to balance has been developed. To investigate this relationship quantitatively, the human body was treated as consisting of 11 rigid body segments, each with six degrees of freedom. A bilateral Selspot II/TRACK data acquisition system provides position and orientation kinematic data for estimation of the trajectories of the individual body segment centers of gravity. From these, the whole body center of gravity is estimated and compared to concurrent force plate center of force data. Center of gravity and center of force excursions agree where dynamics are not significant. The technique may be employed to study quiet stance, response to postural disturbances, or the initiation and coordination of complex movements such as gait.

Adolescent↗
PubMed1990

Whole-body movements during rising to standing from sitting.

Rising to a standing position from a sitting position is one of the most important activities of daily life. We present a total-body analysis of rising from a chair as performed by nine healthy individuals under controlled conditions. We describe four phases of this activity. Phase I is a flexion-momentum phase used to generate the initial momentum for rising. Phase II begins as the individual leaves the chair seat and ends at maximal ankle dorsiflexion. Forward momentum of the upper body is transferred to forward and upward momentum of the total body. Phase III is an extension phase during which the body rises to its full upright position. Phase IV is a stabilization phase. Kinetics and kinematics of the phases are analyzed. The phases are differentiated in terms of momentum and stability characteristics. Clinical implications of the mechanics of rising are discussed.

Adult↗
PubMed1989

Contact pressures from an instrumented hip endoprosthesis.

A pressure-measuring Moore-type endoprosthesis was implanted in a seventy-three-year-old patient who had sustained a displaced fracture of the femoral neck. The measurement and telemetry of contact pressures in the hip began in the operating room, and data were acquired periodically for more than thirty-six months. Unexpectedly high localized contact pressures between the acetabular cartilage and the prosthesis were recorded. Early in the period of recovery, activities such as using a bedpan or performing isometric exercise produced pressures that were close to those recorded during normal walking. The highest pressure, eighteen megapascals, was recorded one year postoperatively, while the patient was rising from a chair. High pressures occurred in the superior and posterior aspects of the acetabulum.

Acetabulum↗
PubMed1986

Contact pressures in the human hip joint measured in vivo.

The pressures on human articular cartilage have been measured in vivo. An instrumented femoral head prosthesis that telemeters interarticular pressure at 10 discrete locations 253 times per second was implanted in apposition to natural acetabular cartilage. Data were acquired during surgery, recovery, rehabilitation, and normal activity, for longer than 1 year after surgery. Pressure magnitudes were synchronized with body-segment kinematic data and foot-floor force measurements so as to locate transduced pressure areas on the natural acetabulum and correlate movement kinematics and dynamics with local cartilage pressures. The data reveal very high local (up to 18 MPa) and nonuniform pressures, with abrupt spatial and temporal gradients, that correlate well both in magnitude and distribution with in vitro data and computer simulations of synovial joint mechanics. Peak pressures in vivo are, however, considerably higher than pressures measured in vitro under the putative forces experienced by the joint in life, particularly in normal movements where cocontraction occurs in agonist and antagonist muscles across the hip joint. Thus, extant gait-analysis studies which apply inverse Newtonian calculations to infer joint forces establish the lower limit on such forces, since such analyses include only the net muscular torques about the joint and cannot account for the contribution of the increment in joint force due to muscular cocontraction. Our data also contribute to the understanding of normal synovial joint tribology and the possible role of mechanical factors in the deterioration evident in osteoarthritis. Further, design criteria for both partial and total hip replacement prostheses and specific aspects of rehabilitation protocols following hip surgery (e.g., the extent to which crutches and canes unload the hip joint) warrant reconsideration in light of the extraordinary high pressures measured during the activities of daily living.

Biomechanical Phenomena↗