Biomedical subjects

T M Kepple

Publications and source records attributed to T M Kepple.

8 recordsLinked to original sources

PubMed1998

A three-dimensional musculoskeletal database for the lower extremities.

A three-dimensional musculoskeletal database of the lower extremities has been developed for use in human musculoskeletal models. The locations of idealized muscle attachments on the pelvis, both femurs, both tibias and fibulas, and both feet were accurately digitized for 52 dried skeletal specimens. The mean specimen heights were 177.5 cm (male) and 166.2 cm (female) and the mean specimen age at the time of death was 48.8 yr. Statistical accumulation and scaling techniques were used to generate highly representative normative models, which were divided into groups and tested for differences based on gender and race. From the test results, the pelvis was divided into a male model (RMS = 8.6 mm), a black female model (RMS = 7.0 mm) and a white female model (RMS = 7.3 mm). The foot was separated into black (RMS = 3.7 mm) and white models (RMS = 3.6 mm). Single models were used for the femur (RMS = 6.5 mm) and the tibia/fibula (RMS = 3.7). Containing over 12000 anatomical landmarks digitized from 52 dried skeletons, this study represents an improvement over previous databases by an order of magnitude.

Black People↗

PubMed1998

Forefoot deformity, pain, and mobility in rheumatoid and nonarthritic subjects.

OBJECTIVE: To evaluate how painful metatarsal arthritis affects foot and ankle mechanics and mobility. METHODS: We studied 16 symptomatic forefeet in 10 patients with rheumatoid arthritis (RA) and compared them with 14 asymptomatic forefeet in 7 nonarthritic subjects. RA limbs with significant disease at other locations were excluded. We measured pain and deformity of the foot using a visual analog scale and a modified articular index. A video based 3 dimensional gait analysis system and force platform were used to collect data on subjects walking barefoot at a self-selected pace according to an established protocol. Mobility level was quantified using the Sickness Impact Profile (SIP) ambulation subscale. RESULTS: We observed considerable pain and deformity of the forefeet of RA subjects. During gait, motion and force measures revealed that RA subjects significantly (p < 0.005) delayed and reduced forefoot loading, which minimized use of the foot as a rigid level for push off. As a result, stride lengths were shorter and gait was slower compared to nonarthritic subjects. SIP scores revealed that these changes in gait resulted in moderate disability in RA subjects (p=0.05). CONCLUSION: Impairments of the forefoot due to RA include pain and deformity, which produce characteristic stance phase abnormalities in foot function, a slow walking speed, and moderate disability.

Arthritis, Rheumatoid↗

PubMed1996

Improved agreement of foot segmental power and rate of energy change during gait: inclusion of distal power terms and use of three-dimensional models.

Traditional models used to calculate foot segmental power have yielded poor agreement between foot power and the rate of energy change during the stance phase of gait and limited the applicability of foot segmental power analyses to swing phase only. The purpose of this study was to improve the agreement of foot segmental power and rate of energy change by using more inclusive models to calculate foot segmental power and energy. The gait of 15 adult subjects was studied and models were used to calculate foot segmental power that included either the proximal terms only (Model P, the most common method in the literature) or both proximal and distal terms (Model PD, a mathematically complete model). Power and energy terms were computed in two ways, from sagittal plane vector components only (two-dimensional condition) and from complete three-dimensional components (three-dimensional condition). Results revealed that the more inclusive the model, the higher the agreement of foot power and rate of energy change. During stance phase, Model P produced poor agreement (r(c) = 0.108) for both two-dimensional and three-dimensional conditions, Model PD-2D yielded higher agreement (r(c) = 0.645), and Model PD-3D exhibited nearly perfect agreement (r(c) = 0.956). The advantages of a segmental power analysis include the ability to identify the mechanisms of energy transfer into and out of the foot during movement. The results of this study suggest that foot power analyses are valid when using Model PD-3D to describe foot function during locomotion.

Adult↗

PubMed1995

A technique to evaluate foot function during the stance phase of gait.

A technique to measure foot function during the stance phase of gait is described. Advantages of the method include its three-dimensional approach with anatomically based segment coordinate systems. This allows variables such as ground reaction forces and center of pressure location to be expressed in a local foot coordinate system, which gives more anatomical meaning to the interpretation of results. Application of the measurement technique to case examples of patients with rheumatoid arthritis demonstrated its ability to discriminate normal from various levels of pathological function. Future studies will utilize this technique to study the impact of pathology and treatment on foot function.

Adolescent↗

PubMed1994

Assessment of a method to estimate muscle attachments from surface landmarks: a 3D computer graphics approach.

A method for estimating the locations of muscle origins and insertions from the measurement of surface landmarks was evaluated using two indirect accuracy tests and a three-dimensional computer graphics program. For each of four lower extremity anatomical segments, a least-squares technique was used to map the measured locations of three landmark targets to their anatomically based locations. The residual errors, obtained from the applications of the least squares, supplied the first indirect accuracy test. These residual errors were between 6 and 12 mm for the four anatomical segments when averaged over ten subjects. The second indirect accuracy test was conducted by comparing the predicted locations of end points on two adjacent segments forming a joint. Errors in aligning adjacent end points were between 12 and 29 mm for three anatomical joints when averaged over ten subjects. A three-dimensional computer graphics program was developed by the authors and demonstrated that the static testing techniques alone were insufficient to evaluate the quality of the muscle origin and insertion estimates. Any evaluation of muscle lengths, velocities and lines-of-action from surface landmarks should examine the estimates made from motion data, and should address both the ability of the model to fit the subjects as well as model's ability to represent the geometry of the musculoskeletal system.

Anthropometry↗

PubMed1994

Translational and rotational joint power terms in a six degree-of-freedom model of the normal ankle complex.

We hypothesized that defining joint power (JP) merely on the basis of joint rotations ignores important translational power terms, and may not adequately represent the energy flow profile for a given muscle group. A novel six degree-of-freedom (6 DOF) model of the ankle complex was implemented, accounting for previously ignored joint translations as well as traditional rotations. Foot and shank kinematic and kinetic data were collected over a stride cycle on five male and five female adults, walking five trials each at 0.69 statures s-1. During intra-subject analyses, ensemble averages were calculated (n = 5) for JP associated with each DOF, and for related velocity and force/moment data. Translational joint velocities typically peaked below 10% of the mean walking velocity. The largest peak in JP occurred for the rotational DOF associated with dorsi/plantar flexion (360 W). The next largest peak in JP was for the vertical translational DOF, and was nearly 10% of the predominant peak. Positive work during push-off was significantly less p < or = 0.05) for the 6 DOF model (27.9 J) than for either 1 or 3 DOF rotational models (30.3 and 29.9 J, respectively). Negative work during early stance was significantly less for the 6 DOF model (-10.3 J) than for either the 1 or 3 DOF models (-13.1 and -12.6 J, respectively). Inter-subject analyses (n = 50) were conducted for JP data only, with similar results. We conclude that translational JP terms are of practical importance in mechanical energy studies, and may be of particular concern when evaluating energy storing prostheses, when summing total power at several joints, and when studying pathologies that disturb joint geometry.

Adult↗

PubMed1990

Kinematic-based technique for event time determination during gait.

A kinematic-based technique for the estimation of the times at which gait events occur is presented. A kinematic-based model (KM) is defined by the trajectory of a point, which has an anatomically fixed location on the subject's body, about a time at which a measurement system defined gait event takes place. The times at which subsequent occurrences of the gait event takes place are determined by identifying the kinematic pattern that best fits the previously defined KM. The results of an experiment that used the gait patterns of a normal and a pathological walker indicate that the accuracy of the algorithm is limited by the kinematic data sampling interval and that optimal kinematic predictors of gait event times occur within the primary (sagittal) plane of motion. The technique is intended to obviate the need for multiple force plates, instrumented floors and instruments which are worn by the subject for the purpose of determining the times at which gait events occur.

Adult↗

PubMed1990

A video-based technique for measuring ankle-subtalar motion during stance.

This study was designed to demonstrate that an accurate and reliable technique for measuring the rotational motion between rigid bodies can be developed from a video-based data collection system. Tests on the accuracy of the rotational measurements demonstrated that for each of five trials, under three test condition, mean errors of less than 0.4 degrees and standard deviations of less than 0.2 degrees were found for all three joint axes. The reliability of the technique for evaluating ankle-subtalar motion during stance was also demonstrated, and the technique was then applied to evaluate ankle-subtalar motion during the stance phase of gait. The rotational motion of the combined ankle-subtalar joint was characterized by complexity and inter-subject variability. Two simplified models previously used to describe ankle-subtalar motion were tested using the current data and were proven to be inadequate for describing ankle-subtalar motion during stance.

Adult↗