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PubMed1992

Traumatic transection. An unusual fatal pedestrian injury.

Speed, alcohol, and pedestrian injuries constitute disturbing components of the spectrum of trauma in the developing world. The complete fatal transection of a pedestrian, at the level of the lower abdomen, by an oncoming automobile traveling at high speed is described. The upper torso was found inside the vehicle, whereas the lower torso was projected some distance ahead, onto the highway. An accident analysis, in order to ascertain the speed of the automobile, is demonstrated and the biodynamic mechanisms of this injury are discussed. The nature of this injury is compared with that of traumatic hemipelvectomy following which survival has been reported.

Accidents, Traffic↗

PubMed1995

Cardiovascular responses to noxious stimuli during isoflurane anesthesia are minimally affected by anesthetic action in the brain.

We investigated the ability of isoflurane to ablate cardiovascular responses to a noxious stimulus (dew-claw clamp) in 10 goats during isoflurane delivery throughout the body and with selective delivery to either the head or torso. Whole-body minimum alveolar anesthetic concentration (MAC) and the concentration blocking autonomic responses (MAC-BAR) were determined. Next, cranial blood (jugular vein) was drained into an oxygenator and reinfused into the head (carotid artery). In six animals (Group I) isoflurane to the torso was maintained at 0.2%-0.3%, and the cranial isoflurane concentration adjusted to determined MAC-BAR; in three animals (Group II) cranial isoflurane was maintained at 0.2%-0.3%, and the end-tidal isoflurane adjusted to determine MAC-BAR. Whole-body MAC was 1.4% +/- 0.3%; whole-body MAC-BAR was 3.7% +/- 0.4%, a concentration range associated with hypotension (46 +/- 8 mm Hg). During bypass, MAC-BAR was 5.6% +/- 2.4% for Group I (P < 0.05) and 2.2% +/- 0.7% for Group II (P < 0.05). Changes in blood pressure, but not heart rate, correlated with the isoflurane concentration, both during the whole-body period and bypass period for Groups I and II. We conclude that isoflurane suppresses the arterial blood pressure response to noxious stimuli, but only with concomitant hypotension, and that the brain has little influence on this response, as its MAC-BAR substantially exceeded whole-body MAC-BAR.

Anesthetics, Inhalation↗

PubMed2000

Extent of hyperbaric spinal anesthesia influences the duration of spinal block.

BACKGROUND: The influence of spread of spinal anesthesia on the duration of spinal blockade has been suggested but never investigated specifically. Because elimination of local anesthetic from subarachnoid space is probably dependent of the surface available for its diffusion and vascular absorption, the current study was designed to evaluate the hypothesis that with a same dose of hyperbaric bupivacaine, a higher anesthetic level would result in a shorter duration of spinal blockade than a lower level. METHODS: Three milliliters (15 mg) of hyperbaric bupivacaine, 0.5%, was injected intrathecally in 40 patients classified as American Society of Anesthesiologists physical status I or H scheduled for lower limb surgery during spinal anesthesia. To obtain significantly different anesthetic levels, the patients were positioned randomly either horizontally or with the torso elevated 30. Regression of sensory level and motor blockade, the appearance of pain at the operative site, and hemodynamic changes were evaluated. RESULTS: The maximum cephalad spread of sensory blockade (expressed as the median with ranges in parentheses) was significantly higher in the horizontal group than in the group with 30-degree elevation of the torso, i.e., T3.5 (T1-T9) versus T10 (T6-L1), with respectively significantly faster regression times (mean ¿ SD) by two segments (216 ¿ 46 mm vs. 253 ¿ 64 mm) and to segment L4 (269 ¿ 53 mm i s. 337 ¿ 58 mm), as well as shorter time to complete motor blockade recovery (173 ¿ 34 mm i s. 233 ¿ 58 mm) and faster appearance of pain at the operative site (221 ¿ 68 mm vs. 271 ¿ 56 mm). CONCLUSION: The results indicate that with the same dose of hyperbaric bupivacaine, the duration of spinal blockade is longer in patients with restricted spread.

Anesthesia, Spinal↗

PubMed1989

Noncardiogenic pulmonary edema after abdominal aortic aneurysm surgery.

Limb ischemia in experimental animals leads to white blood cell (WBC) and thromboxane (Tx)A2 dependent pulmonary dysfunction. This study examines the pulmonary sequelae of lower torso ischemia in 20 consecutive patients aged 63 +/- 5 years (mean +/- SEM) who underwent elective abdominal aortic aneurysm surgery. After 30 minutes of aortic cross-clamping, plasma TxB2 levels had risen from 77 +/- 26 pg/ml to 359 +/- 165 pg/ml (p less than 0.01) and was temporally related to increases in mean pulmonary artery pressure (MPAP) from 18 +/- 1 to 23 +/- 3 mmHg (p less than 0.01), as well as to increases in pulmonary vascular resistance (PVR) from 0.07 +/- 0.02 to 0.12 +/- 0.02 mmHg sec/ml (p less than 0.01). Each time that the aortic clamp was repositioned and with final declamping, after 83 +/- 10 minutes, there were further increases in MPAP to a peak of 32 +/- 2 mmHg (p less than 0.01) and in PVR to 0.26 +/- 0.030 mmHg sec/ml (p less than 0.01), corresponding to a plasma TxB2 level of 406 +/- 177 pg/ml (p less than 0.01). MPAP and PVR returned to baseline values within 30 minutes of declamping. Ten minutes after removal of the aortic clamp, platelet levels had fallen from 180 +/- 41 to 97 +/- 17 X 10(3)/mm3 (p less than 0.01) and WBC levels from 8900 +/- 1100 to 4700 +/- 400/mm3 (p less than 0.01). Both platelets and WBC returned towards normal levels, but at 24 hours, while WBC was elevated at 13000 +/- 900/mm3 (p less than 0.01), platelets were 44% of baseline at 135 +/- 14 X 10(3)/mm3 (p less than 0.01). Four to 8 hours after surgery, pulmonary dysfunction was manifest by increases in physiologic shunt from 9 +/- 2% to 16 +/- 2% (p less than 0.01), and peak inspiratory pressure (PIP) from 23 +/- 2 to 33 +/- 2 cmH2O (p less than 0.01). Chest radiography demonstrated interstitial pulmonary edema in all patients, whereas pulmonary artery wedge pressure was 12 +/- 2 mmHg, excluding the possibility of left ventricular failure. After 24 hours, pulmonary edema had resolved, and the PIP and PaO2 had both returned to baseline. These data indicate that reperfusion of the ischemic lower torso leads to the synthesis of TxA2, an event temporally related to pulmonary hypertension and transient leukopenia with subsequent pulmonary microvascular injury manifest by interstitial edema.

Aged↗

PubMed2001

Estimation of end-expiratory lung volume variations by optoelectronic plethysmography.

OBJECTIVE: To test the capability of optoelectronic plethysmography (OEP) to monitor positive end-expiratory pressure (PEEP)-induced changes of end-expiratory lung volume (EELV) changes in mechanically ventilated paralyzed patients. DESIGN: Laboratory and clinical investigation. SETTING: Intensive care unit of the Ospedale Maggiore Policlinico di Milano. PATIENTS: A total of eight patients with respiratory failure of various degrees, sedated and paralyzed. INTERVENTIONS: PEEP variations (+/-5 cm H2O) relative to the baseline PEEP of 10 cm H2O. MEASUREMENTS AND MAIN RESULTS: In the model protocol, we tested the reproducibility of the OEP by repeating volume measurements of a plastic torso model over a 21-hr period, every 30 mins. The variations of OEP measurements of the torso model (9337 mL value) were encountered in a range of 16 mL (sd = 4 mL). In the patient protocol, we measured the end-expiratory volume of the chest wall (EEVCW) breath-by-breath by OEP before, during, and after the PEEP increase/decrease and we compared its variations with the corresponding variations of EELV measured by helium dilution technique. The regression line between EELV changes measured by helium and EEVCW changes measured by OEP resulted very close to the identity line (slope 1.06, intercept -0.02 L, r(2) = 0.89) and their difference was not related to their absolute magnitude. After PEEP increase, the new steady state of EEVCW was reached approximately in 15 breaths; and, after PEEP decrease, in 3-4 breaths. The slow increase in EEVCW was mainly because of the abdominal compartment. CONCLUSION: OEP measurements of EEVCW accurately reflect the changes of EELV. Furthermore, OEP allows a continuous compartmental analysis, even during unsteady conditions.

Adult↗

PubMed2000

The uncertainty in the activity estimate from a lung count due to the variability in chest wall thickness profile.

Calibration of a lung counter requires the use of a realistic torso phantom. The depth profile of both torso phantoms' (LLNL and JAERI) chest plate covers is fixed and assumed to be equivalent to a person's chest wall; however, ultrasound measurements of humans have shown this to be an approximation. When the depth profile of a calibration phantom is different from that of a subject, then a systematic uncertainty will be introduced into the activity estimate. Monte Carlo simulation has shown that changes in the depth profile of the chest wall thickness affect the counting efficiency. Ultrasound measurements have suggested that the coefficient of variation in the depth profile of the chest wall thickness lies between 13% and 26% for male workers; therefore, the added uncertainty to an activity estimate will be an over or underestimate of about a factor of 1.07 resulting from the different depth profile. The factor will be somewhat higher for females, probably about 1.2 at the extreme. These additional uncertainties resulting from depth profile differences are small compared with other uncertainties commonly encountered in lung counting: detector positioning, deposition patterns of the activity, measurement of the chest wall thickness, etc.

Computer Simulation↗

PubMed2000

Chest wall thickness measurements of the LLNL phantom for small area germanium detector counting.

The Lawrence Livermore National Laboratory (LLNL) phantom was developed to calibrate lung counting systems that are used to estimate plutonium and other low energy photon emitting radionuclides deposited in the lung. Originally, low energy photon counting systems consisted of sodium iodide or phoswich detectors, but they have been largely replaced by smaller germanium detector arrays. The average chest wall thicknesses of the LLNL phantom's torso plate and its overlay plates provided by the manufacturer refer to the regions covered by phoswich detectors; however, germanium detectors are of a different size and are placed in different locations on the phantom's torso plate. Previous work has shown that the manufacturer's data were not applicable for large area germanium detectors. The lung counting system at the Korea Atomic Energy Institute (KAERI) is a small area germanium detector array. Although the detectors are placed within the phoswich circles, only about 25% of the area is covered by the detectors. The LLNL phantom at KAERI has been examined to determine if the manufacturer's data are valid or if new chest wall thickness values must be determined. This paper presents chest wall thickness data for the LLNL phantom with and without its B-series overlay plates at 17 keV, 60 keV, 200 keV, and 1,500 keV and shows that these values are different from the manufacturer's values.

Calibration↗

PubMedDate not supplied

Childrens' distress during burn treatment is reduced by massage therapy.

Before dressing changes, 24 young children (mean age = 2.5 years) hospitalized for severe burns received standard dressing care or massage therapy in addition to standard dressing care. The massage therapy was conducted to body parts that were not burned. During the dressing change, the children who received massage therapy showed minimal distress behaviors and no increase in movement other than torso movement. In contrast, the children who did not receive massage therapy responded to the dressing change procedure with increased facial grimacing, torso movement, crying, leg movement and reaching out. Nurses also reported greater ease in completing the dressing change procedure for the children in the massage therapy group. These findings suggest that massage therapy attenuates young childrens' distress responses to aversive medical procedures and facilitates dressing changes.

Anxiety↗

PubMed1995

Prospective analysis of a rapid trauma ultrasound examination performed by emergency physicians.

The objective of this prospective study was to determine the sensitivity, specificity, and accuracy of the rapid trauma ultrasound examination, performed by emergency physicians, for detecting free peritoneal and thoracic fluid in patients presenting to a level I trauma center with major blunt or penetrating torso trauma. Emergency medicine residents and faculty were trained to perform an ultrasound examination of the torso evaluating for free intraperitoneal, retroperitoneal, pleural, and pericardial fluid. In the 245 study patients, emergency physicians examined 975 intracavitary spaces and demonstrated 64 positive findings for free fluid as documented by computed tomography scan, diagnostic peritoneal lavage, exploratory laparotomy, chest radiography, tube thoracostomy, or formal two-dimensional echocardiography. The rapid trauma ultrasound examination was 90% sensitive, 99% specific, and 99% accurate. Ultrasonography can serve as an accurate diagnostic adjunct in detecting free peritoneal and thoracic fluid in trauma patients. Appropriately trained emergency physicians can accurately perform and interpret these trauma ultrasound examinations.

Abdominal Injuries↗

PubMed1995

Early neutrophil sequestration after injury: a pathogenic mechanism for multiple organ failure.

Polymorphonuclear neutrophils (PMNs) play a pivotal role in the inflammation that precedes multiple organ failure (MOF). In a rat model of MOF, PMNs become primed for enhanced superoxide anion (O2-) release and CD11b expression, sequester in end organs, and produce organ failure. Therefore, we hypothesized that circulating PMNs harvested in the first 24 hours after injury from trauma patients at risk for MOF would (1) exhibit a primed O2- release, (2) upregulate CD11b expression, and (3) show evidence of sequestration in tissues. Extracellular PMN O2- release and CD11b receptor expression were measured at 3, 6, 12, and 24 hours after injury in 33 torso trauma patients with Injury Severity Scores > 15; eight patients (24%) developed MOF. Healthy adults served as controls. PMNs after injury were primed for enhanced in vitro O2- release at 3, 6, 12, and 24 hours after injury, indicating prior in vivo priming. CD11b expression was also increased at 6, 12, and 24 hours after injury. Circulating PMN numbers increased sharply at 3 hours after injury, before decreasing dramatically at 6 and 12 hours, suggesting end organ sequestration. At 12 hours after injury, declines in circulating PMNs were significantly greater in MOF than in non-MOF patients (p < 0.05). These data indicate that PMNs are quickly mobilized into the circulation after injury and then primed for enhanced O2- release and CD11b expression. PMN priming appears to be a necessary preamble to PMN sequestration in patients with major torso trauma. Upregulation of PMN function, accompanied by subsequent end organ sequestration, may represent an important early event in the pathogenesis of MOF after injury.

Adult↗

PubMed1998

The indeterminate abdominal sonogram in multisystem blunt trauma.

BACKGROUND: North American trauma centers are beginning to note the limitations of emergent torso sonography. The purpose of this prospective study was to evaluate the frequency, causes, associations, and sequelae of indeterminate (IND) sonograms in blunt trauma. METHODS: Among adult blunt trauma patients assessed with screening torso sonography, clinician sonographers recorded the abdominal sonogram as positive, negative, or IND for free fluid. Patients with IND sonograms were further investigated with repeat sonography, computed tomography, or diagnostic peritoneal lavage. RESULTS: Among 417 patients with blunt trauma (mean Injury Severity Score = 21) managed with sonography, there were 28 (6.7%) IND and 389 (93.3%) non-IND sonograms. Sonograms were IND because of patient factors in 71% (20 of 28) and because of operator factors in 29% (8 of 28). None of the 28 patients were managed with repeat sonography alone. All 4 diagnostic peritoneal lavage examinations gave negative results, whereas 8 of 23 computed tomographic scans were abnormal (6 of 8 patients underwent laparotomy). The mean time required for diagnostic workup was 117 minutes in the IND group and 48 minutes in the non-IND group (p < 0.001 in both cases). CONCLUSION: This prospective study has demonstrated that IND sonograms are not common at our center (6.7%), are usually attributable to patient factors, and are associated with greater diagnostic time. Patients with IND sonograms require further investigation because they often have injuries requiring laparotomy.

Abdominal Injuries↗

PubMed1990

The venous territories (venosomes) of the human body: experimental study and clinical implications.

The venous architecture of the integument and the underlying deep tissues was studied in six total-body human fresh cadavers and a series of isolated regional studies of the limbs and torso. A radiopaque lead oxide mixture was injected, and the integument and deep tissues were dissected and radiographed. The sites of the venous perforators were plotted and traced to their underlying parent veins that accompany the source (segmental) arteries. A series of cross-sectional studies were made in one subject to illustrate the course of the perforators between the integument and the deep tissues. The veins were dissected under magnification to identify the site and orientation of the valves. Results revealed a large number of valveless (oscillating) veins within the integument and deep tissues that link adjacent valved venous territories and allow equilibration of flow and pressure throughout the tissue. Where choke arteries define the arterial territories, they are matched by boundaries of oscillating veins in the venous studies. The venous architecture is a continuous network of arcades that follow the connective-tissue framework of the body. The veins converge from mobile to fixed areas, and they "hitchhike" with nerves. The venous drainage mirrors the arterial supply in the deep tissues and in most areas of the integument in the head, neck, and torso. In the limbs, the stellate pattern of the venous perforators is modified by longitudinal channels in the subdermal network. However, when an island flap is raised, these longitudinal channels are disconnected, and once again the arterial and venous patterns match. Our venous studies add strength to the angiosome concept. Where source arteries supply a composite block of tissue, we have demonstrated radiologically and by microdissection that the branches of these arteries are accompanied by veins that drain in the opposite direction and return to the same locus. Hence each angiosome consists of matching arteriosomes and venosomes. The clinical implications of these results are discussed with particular reference to the design of flaps, the delay phenomenon, venous free flaps, the pathogenesis of flap necrosis, the "muscle pump," varicose veins, and venous ulceration.

Aged↗

PubMed1997

Anthropomorphic breast measurement: protocol and results in 50 women with aesthetically perfect breasts and clinical application.

This paper presents a simple protocol for the measurement and evaluation of the difficult physiognomy of the female breast and the application of the protocol in clinical practice. The protocol includes measurement of the breast and its landmarks and their relevant position from fixed skeletal points. Volume was measured with the Grossman-Roudner device. The protocol provides a useful tool in the accurate evaluation of patients preoperatively and in the assessment of surgical results. The protocol is compared with the two previously reported protocols. The paper presents the anthropomorphic measurements of 50 women with aesthetically perfect breasts utilizing this protocol. Aesthetically perfect was defined as a nonptotic breast in which no common aesthetic procedure would be considered appropriate (excluding augmentation) to enhance the breast's form. Results were compared with those reported in the two previous studies. The paper presents the clinical correlation obtained by statistical analysis of the results of the measurements of the 50 women. Although the results of the measurements indicate the range and variance in the aesthetically perfect breast, there still was a statistically significant correlation of some of the parameters of the breast and torso shape to breast volume. This correlation can be used preoperatively to predict desired breast shape and volume in breast augmentation, reduction, and reconstruction. Clinical application of the concepts proposed will lead to better surgical goal orientation and improve evaluation of surgical results. A formula for calculating appropriate breast size based on torso parameters is presented.

Adolescent↗

PubMed2001

Giant congenital nevi: a 20-year experience and an algorithm for their management.

A variety of treatment options exists for the management of giant congenital nevi. Confusion over appropriate management is compounded because not all giant congenital nevi are pigmented, and malignant potential varies between different types. The present study sought to define factors in the presentation of giant congenital nevi that could provide an algorithm for their management, with respect to both the extent of resection and subsequent reconstructive options.A retrospective review of all patients who presented with a congenital nevus of 20 cm2 or greater since 1980 was performed, distinguishing among nevi involving the head and neck, the torso, and the extremities. Sixty-one patients with giant congenital nevi were evaluated (newborn to age 16 years), of which 60 nevi in 55 patients have been operated on. Giant congenital nevi having malignant potential were pigmented nevi (53 patients) and nevus sebaceus (four patients). Those not having malignant potential were verrucous epidermal nevi (three patients) and a woolly hair nevus (one patient). Of the 60 giant congenital nevi operated on, expanded flaps were used in 25, expanded full-thickness skin grafts were used in 10, split-thickness or nonexpanded full-thickness skin grafts were used in 13, and serial excision was used in 30. After 1989, operations tended to use multimodality treatment plans, with an increased use of expanded full-thickness grafts and immediate serial tissue expansion. The use of serial excision, particularly in the extremities, also increased after 1989. Serial excision was the treatment of choice when it could be completed in two procedures or less, which occurred in more than 80 percent of cases using serial excision alone. Expanded flaps were the most common mode of reconstruction in the head and neck region and were used in 49 percent of these procedures. Serial excision was the most common form of treatment in the extremities, used in 50 percent of procedures. Tissue expansion in the extremities was infrequently used to provide an expanded flap (8 percent of procedures), whereas it was frequently used to provide expanded full-thickness skin grafts harvested from the torso (used in 31 percent of procedures). On the basis of these data, algorithms for the extent of resection and subsequent reconstructive options for giant congenital nevi were developed. Their management should be formulated relative to pigmentation, malignant potential, and anatomic location of the respective lesions.

Adolescent↗

PubMed1986

A study of lumbosacral orientation under varied static loads.

This paper describes a study of lumbar and sacrum orientations in select standing postures with the patient holding different loads in the hands. Vertebral rotation data were gathered from two young, healthy men and two young, healthy women while they performed static lifts at two load levels and in postures ranging from erect standing to deep squatting. The results disclosed a predictable reorientation of the sacrum and lumbar spine for both men and women as a function of torso and knee angles. Nonlinear second-order regression models of torso angle and knee angle versus reorientation angle were fit to the data with resulting r2 values of about 0.89. Load was not found systematically to affect the sacrum/lumbar reorientation.

Adult↗

PubMed1995

The effect of different surgical releases on thoracic spinal motion. A cadaveric study.

STUDY DESIGN: Two separate experiments (A and B), each involving six human cadaveric torsos with intact rib cages and sternums, were done to determine the effect of two different sequences of surgical releases (at T8-T9) on thoracic spinal motion. OBJECTIVES: Experiment A was designed to test the effects of three releases in sequence from anterior to posterior, analogous to a two-stage operative treatment with anterior and posterior releases. Experiment B, which involved three releases, was designed to determine 1) if unilateral posterior total facetectomy alone allowed a significant increase in motion and 2) if rib head resection without discectomy allowed a significant increase in motion. SUMMARY OF BACKGROUND DATA: In the surgical treatment of thoracic spinal deformity, surgical release is often done to impart additional flexibility to the spine. Available releases include discectomy, rib head resection, and facetectomy. There is little work to date on the relative importance of the disc, rib head, and facet joint in the stability of the thoracic spine. METHODS: In experiment A and experiment B, the cadaveric torsos were mounted on a custom-made loading frame. Mechanical testing (using weights, pulleys, and digital goniometers) was done after each surgical release to measure the extent of angular rotation in the coronal plane (right lateral bending and left lateral bending) and in the sagittal plane (flexion and extension). RESULTS: The combination of rib head resection and radical discectomy provided the greatest increase in thoracic spinal motion. Standard discectomy alone did not allow a significant increase in motion. Rib head resection without discectomy did not allow a significant increase in motion. Unilateral posterior total facet excision did not allow a significant increase in motion. CONCLUSIONS: These experiments indicate that the combination of rib head resection and radical discectomy may be the optimal thoracic spinal release.

Aged↗

PubMed1995

Body motion patterns during a novel repetitive wheel-rotation task. A comparative study of healthy subjects and patients with low back pain.

STUDY DESIGN: This study evaluated performance differences between patients with chronic low back pain and a control group during their performance of a novel functional capacity task. OBJECTIVE: To 1) evaluated strength and endurance differences between patients and control subjects, 2) test for movement pattern differences between these groups, and 3) evaluate how these patterns changed with repetitive performance of the wheel-turning task. SUMMARY OF BACKGROUND DATA: Despite increased emphasis on quantifying functional capacities, few well-controlled studies comparing the performances of patients with low back pain with those of control subjects have appeared in the literature, particularly for movement patterns. METHODS: Forty patients with low back pain and 40 control subjects performed a sustained isodynamic wheel turning task. This task was selected because it simultaneously combined several common pain-related movements. A set of kinematic measures to characterize the basic movement patterns during this task were developed. RESULTS: Control subjects produced significantly higher levels of static torque and completed significantly more wheel-turning repetitions. Patients with low back pain exhibited significantly less upper torso and pelvic motion, upper torso rotation, and lateral trunk flexion than those in the control group. CONCLUSION: The dissimilar movement strategies found between the patient and control groups suggests that factors beyond more global physical explanations (e.g., deconditioning) may be important in accounting for the large discrepancy between these groups regarding the amount of work performed. These findings, along with the basic kinematic patterns developed in this study, may have important implications for determining the efficacy of instruction in body mechanics and treatment outcome for patients with chronic low back pain.

Adult↗

PubMed1996

An electromyographic study of unresisted trunk rotation with normal velocity among healthy subjects.

STUDY DESIGN: An axial rotation tester was designed and fabricated for the study. This allowed stabilization of seated subjects (hip down) and coupling of shoulders, permitting axial rotation and coupled lateral flexion. Using this device, a "flexion-extension free" axial rotation was executed for studying its characteristics. OBJECTIVES: To determine the mechanism of initiation, sustenance, and execution of axial rotation. This was planned to be done by determining the phasic relationship of various torso muscles in the initiation, execution, and termination of axial rotation. Another objective was to determine the total and relative contribution of torso muscles in axial rotation and the small segments of these activities. SUMMARY OF BACKGROUND DATA: There only are a few studies conducted on axial rotation. Generally, these have investigated isometric maximal voluntary contraction in neutral or prerotated postures. The two studies that have reported isokinetic axial rotation have investigated maximal efforts. No study in literature has reported initiation, termination, and execution of unresisted normal velocity axial rotation. METHODS: Fifty healthy young subjects executed a full cycle of axial rotation, starting from neutral position to their extreme left, continuing to their extreme right, and finally moving to the neutral posture in one smooth motion without stopping anywhere. The electromyographic results of external obliques, internal obliques, rectus abdominis, pectoralis major, erectores spinae at T10 and L3, and latissimus dorsi were measured bilaterally simultaneously during this trunk rotation. The timing and relative magnitude analyses were done to determine the global and individual muscle contributions in axial rotation. The correlation between electromyographic and angular displacement, and nonlinear curve fitting regression analyses were performed to decipher individual muscles behavior. RESULTS: The pattern of muscle activation was variable. However, contralateral external obliques, ipsilateral erector spinae, and latissimus dorsi became active before other muscles. These were agonists and the others were antagonists or stabilizers. The agonists contributed 65% of the total electromyographic output, whereas antagonists and stabilizers contributed 35%. The muscle activities during onset and offset periods were biphasic with significantly different slopes. CONCLUSIONS: It was concluded that the axial rotation is achieved through the activities of agonists, and return to neutral position is because of elastic recoil controlled by agonistic muscles. A range of approximately 10-15 degrees on either side of the anatomical midsagittal plane involves little muscle effort, but beyond this region, the osteoligamentous structures become stiff and require increasing effort to execute axial rotation.

Abdominal Muscles↗