Biomedical subjects

M P Wachowiak

Publications and source records attributed to M P Wachowiak.

4 recordsLinked to original sources

PubMed2000

Wavelet-based noise removal for biomechanical signals: a comparative study.

The purpose of this paper is to present wavelet-based noise removal (WBNR) techniques to remove noise from biomechanical acceleration signals obtained from numerical differentiation of displacement data. Manual and semiautomatic methods were used to determine thresholds for both orthogonal and biorthogonal filters. This study also compares the performance of WBNR approaches with four automatic conventional noise removal techniques used in biomechanics. The conclusion of this work is that WBNR techniques are very effective in removing noise from differentiated signals with sharp transients while leaving these transients intact. For biomechanical signals with certain characteristics, WBNR techniques perform better than conventional methods, as indicated by quantitative merit measures.

Algorithms↗

PubMed1999

A demonstration of validity of 3-D video motion analysis method for measuring finger flexion and extension.

This study demonstrates the validity of using 3-D video motion analysis to measure hand motion. Several researchers have devised ingenious methods to study normal and abnormal hand movements. Although very helpful, these earlier studies are static representations of a dynamic phenomenon. Despite the many studies of hand motion using scientifically impeccable techniques, little is known about digital motion, and there are still few researchers investigating dynamic three-dimensional motion of the hand. Results from a three-camera video motion analysis system were compared to those from the "gold standard", 2-D lateral view fluoroscopy. We used these two methods to record hand motion simultaneously during unrestricted flexion and extension of the index finger of the dominant hand in 6 neurologically normal, healthy volunteers. After collection and post-processing, the waveforms of the PIP, DIP and MCP joint angles were compared using the adjusted coefficient of multiple determination (R2(a), or CMD). The mean CMD values for the MCP, PIP and DIP joint angle waveforms were 0.96, 0.98 and 0.94, respectively, suggesting a close similarity between motion of comparable joints analyzed by the 2-D and 3-D methods. This shows that the method of 3-D motion analysis is capable of accurately quantifying digital joint motion. It is anticipated that 3-D motion analysis, in addition to being used as a research tool, will also have clinical applications such as surgical planning in neuromuscular disorders and the documentation of abnormal motion in many other pathological hand conditions.

Biomechanical Phenomena↗

PubMed1999

A deficient anterior cruciate ligament does not lead to quadriceps avoidance gait.

Without an intact anterior cruciate ligament (ACL) to resist anterior tibial translation, it is commonly believed that ACL-deficient patients employ alterations in walking. Although there is no consensus in the literature about the specific kinematic and kinetic adaptations in these patients with ACL tears, the gait adaptation of quadriceps avoidance is perhaps the one most popularized. The purpose of our study was to determine whether quadriceps avoidance is common in patients with ACL-deficiency. We used a video-based motion analysis system and surface electromyography (EMG) to study 18 patients with ACL-deficiency. All patients demonstrated an internal knee extension moment during early mid-stance (similar to normal subjects). Quadriceps EMG activity was noted throughout most of stance. No patients demonstrated an internal knee flexion moment, a decreased internal knee extension moment or a decreased duration of quadriceps EMG activity during stance. The findings of this study would suggest that quadriceps avoidance as a gait adaptation in ACL-deficient patients may be less common than previously reported.

Adult↗

PubMed1998

The motion path of the digits.

This study investigates whether the path taken by the fingertips of the human hand during unrestricted flexion and extension follows a precise mathematical pattern: an equiangular spiral. Eight normal subjects participated in the study. Subjects performed numerous flexion and extension trials at a random speed. Motion was recorded by a 6-camera, 3-dimensional motion analysis system with 24 retroreflective markers affixed to the dominant hand at predetermined locations. Four hundred eighty flexion-extension arcs were analyzed. We used the coefficient of multiple determination to compare the flexion and extension motion arc of each finger to an equiangular spiral curve derived mathematically. Our results indicate that the path of the hand during flexion and extension closely follows the path of an equiangular spiral with the coefficient of multiple determination values consistently above 0.95.

Adult↗