Biomedical subjects

Mary E Sesto

Publications and source records attributed to Mary E Sesto.

5 recordsLinked to original sources

PubMed2006

Upper limb dynamic responses to impulsive forces for selected assembly workers.

This study evaluated the upper limb, dynamic, mechanical response parameters for 14 male assembly workers recruited from selected jobs based on power tool use. It was hypothesized that the type of power tool operation would affect stiffness, effective mass, and damping of the upper extremity; and workers with symptoms and positive physical examination findings would have different mechanical responses than asymptomatic workers without physical examination findings. Participants included operators who regularly used torque reaction power hand tools, such as nutrunners and screwdrivers, and nontorque reaction power hand tools, such as riveters. The mechanical parameters of the upper limb were characterized from the loading response of an apparatus having known dynamic properties while worker grasps an oscillating handle in free vibration. In addition, all workers underwent a physical examination, magnetic resonance imaging, and completed a symptom survey. Workers were categorized as controls or cases based on reported forearm symptoms and physical exam findings. A total of seven workers were categorized as cases and had less average mechanical stiffness (46%, p > 0.01), damping (74%, p > 0.01), and effective mass (59%, p > 0.05) than the seven workers categorized as controls. Magnetic resonance imaging (MRI) findings suggestive of muscle edema were observed for two workers classified as cases and who regularly used torque reaction power tools. No MRI enhancement was observed in the seven subjects who did not regularly use torque reaction power tools. The ergonomic consequences of less stiffness, effective mass, and damping in symptomatic workers may include reduced capacity to react against rapidly building torque reaction forces encountered when operating power hand tools.

Adult↗

PubMed2005

Anatomical and mechanical changes following repetitive eccentric exertions.

BACKGROUND: Submaximal eccentric exertions occur occupationally when rapidly rising tool-generated forces exceed the operator's capacity to react against them. The purpose of this study was to investigate the effects of short duration repetitive submaximal eccentric forearm exertions at levels comparable to industrial power hand tool use on dynamic mechanical properties (stiffness, effective mass and damping) and on forearm edema. METHODS: This study investigated changes following short term repetitive submaximal eccentric exertions comparable to occupational levels. Eight male participants exercised eccentrically for 30 min at 50% of isometric maximum voluntary contraction forearm supination in a posture and loading similar to power hand tool use in the workplace. Dynamic mechanical properties (stiffness, effective mass and damping) of the upper limb were measured before, immediately following, and daily for three days after the activity. An MRI scan to assess edema was also performed for five of the participants before, on day one and day three following the activity. FINDINGS: Mechanical stiffness decreased 51% (P < 0.05) and effective mass decreased 43% (P = 0.052) immediately following eccentric exercise. Average isometric strength also decreased 42% immediately following exercise (P < 0.01) and pain persisted for two days. The recovery of static strength however was not correlated with changes in mechanical stiffness (r = 0.56) or effective mass (r = 0.30). The exercised arms had a 360% increase (P < 0.01) in supinator-extensor T(2) relaxation time difference, a quantifiable measure of edema, one day after exercise while the non-exercised arms had no significant changes. INTERPRETATION: Changes in both T(2) relaxation time, indicative of edema, and forearm mechanical properties, were observed following short duration submaximal repetitive exercise. If similar changes in dynamic mechanical properties of the upper extremity occur following repetitive submaximal eccentric activity in the workplace, they could negatively impact the ability of the arm to react to rapid forceful loading during repetitive industrial work activities and increase mechanical loading of the upper limb.

Adaptation, Physiological↗

PubMed2004

Upper limb mechanical changes following short duration repetitive eccentric exertions.

BACKGROUND: Power hand tool use is considered a risk factor for upper extremity musculoskeletal disorders. It is unclear if submaximal eccentric activity inherent to power tool use adversely affects the mechanical properties of muscle. METHODS: This study investigated in vivo changes in human upper limb dynamic mechanical properties following exposure to short-term repetitive submaximal eccentric exertions that are similar to operating an industrial power hand tool. Eighteen subjects (12 males and 6 females) were assigned to one of three exercise groups (isometric, eccentric or control) and exercised 10 min for 60 repetitions at 50% of isometric forearm supination maximum voluntary contraction. Supination strength and dynamic mechanical properties (stiffness, effective mass, and damping) of forearm rotation, modeled as a single-degree-of-freedom system during maximal exertion, were ascertained prior to exercise, immediately following exercise and 24 h later. FINDINGS: Strength decreased for the isometric (17%) (P < 0.05) and eccentric (34%) (P < 0.01) groups following exercise. Only the eccentric exercise group had a reduction in mechanical stiffness (53%) (P < 0.01) and effective mass (58%) (P < 0.05). The other groups had no changes in mechanical properties. INTERPRETATION: The change in mechanical properties following repetitive submaximal eccentric activity could negatively impact the ability of the arm to react to rapid forceful loading during repetitive industrial work activities and may indicate mechanical strain on the upper limb.

Adaptation, Physiological↗

PubMed2004

Functional tests to quantify recovery following carpal tunnel release.

BACKGROUND: An objective test is needed to evaluate outcome following carpal tunnel release. A method to evaluate sensory and motor function related to carpal tunnel syndrome was investigated. METHODS: Thirty-six candidates for carpal tunnel surgical procedures underwent a physical examination and nerve-conduction studies and completed a survey regarding symptoms. A battery of psychomotor and sensory tests was administered bilaterally immediately before surgery and again six weeks after surgery. The outcome variables included dynamic sensory gap-detection thresholds and rapid pinch-and-release rates. RESULTS: The average gap-detection threshold for the index finger in the surgical-treatment group demonstrated a 43% improvement, decreasing from 0.14 mm preoperatively to 0.08 mm at six weeks postoperatively (p < 0.01). The average gap-detection threshold for the index finger in the non-surgical-treatment group demonstrated no significant improvement, decreasing from 0.10 mm preoperatively to 0.08 mm postoperatively (p = 0.10). With the upper force level set at 10% of the maximum voluntary contraction, the average pinch rate in the surgical-treatment group demonstrated a 20% improvement, increasing from 6.65 pinches per second preoperatively to 7.96 pinches per second postoperatively (p < 0.001). The average pinch rate in the non-surgical-treatment group demonstrated a 7% improvement, increasing from 6.89 pinches per second preoperatively to 7.37 pinches per second at six weeks postoperatively (p < 0.05). CONCLUSIONS: Measurable and significantly greater improvement was observed when the surgical-treatment group was compared with the non-surgical-treatment group in terms of these two sensory and psychomotor functional testing outcomes at six weeks. LEVEL OF EVIDENCE: Therapeutic study, Level II-1 (prospective cohort study). See Instructions to Authors for a complete description of levels of evidence.

Adult↗

PubMed2003

Functional deficits in carpal tunnel syndrome.

BACKGROUND: Carpal tunnel syndrome (CTS) is a major occupational illness in the US. The Wisconsin Test is a quantitative computer-controlled test battery designed for measuring sensory and psychomotor function. Subjects were recruited from industrial jobs at high-risk for CTS to determine if subtle sensory and motor deficits were observable in a working population. Outcomes were studied for potential use as an injury surveillance instrument. METHODS: A total of 208 subjects participated (72 males and 136 females). Participants completed a symptom survey, were given a physical examination, administered nerve conduction tests, and were tested using the Wisconsin Test battery. RESULTS: The greatest functional deficits were observed when nerve conduction findings were positive and were accompanied by either positive symptom survey outcomes or positive physical exam findings. The presence of symptoms alone were not significantly associated with motor deficits and no significant sensory threshold differences were observed among subjects categorized using any single criterion (i.e., nerve conduction, symptom reports, or examination). CONCLUSIONS: Measurable and quantifiable sensory and psychomotor deficits were observed in a working industrial population, and were greatest when positive symptoms or physical exam was accompanied by positive nerve conduction test findings. These data show that clinical criteria used in the diagnosis of CTS corresponds with functional psychomotor and sensory impairments measured in these tests.

Adolescent↗