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PubMed1987

Relative mechanical load on back and hip muscles in standing position when handling materials manually. A study of packing work.

Muscular load on the back and hip muscles was quantified and compared using a muscular strength utilization ratio (MUR). The MUR was obtained by dividing the total moment about the bilateral joint axis by the counteracting maximum muscular strength at the same joint angle. 72 different postures during simulated packing work were studied, with different combinations of box size, angle, edge height and weight. The MUR was calculated for a large, an average sized and a small man depending on whether they were all either strong, of average strength, or weak, thus giving nine MUR values for each posture. For a weak man, the MUR exceeded 100% in many postures. The largest box at a zero- or 30-degree angle to the horizontal with its upper edge 20 cm below elbow height gave the highest MUR, while the smallest box angled at 90 degrees with the upper edge 10 cm above elbow height gave the lowest. The presented concept of relating joint load to strength is proposed for use in preventive ergonomic counselling and in vocational rehabilitation.

Adult↗
PubMed1999

The frequency of positive common spinal clinical examination findings in a sample of premenstrual syndrome sufferers.

OBJECTIVE: As part of a randomized clinical trial to determine the efficacy of chiropractic therapy on premenstrual syndrome (PMS), subjects were evaluated for initial underlying spinal dysfunction. SUBJECTS: Fifty-four subjects with diagnosed PMS (using a Moos PMS questionnaire plus daily symptom monitoring) and 30 subjects with no diagnosable PMS were recruited by newspaper advertising and referrals. DESIGN: All subjects underwent a full history and physical and chiropractic examination carried out by 1 of 2 fully qualified and registered chiropractors, each with a minimum of 10 years experience. The results of the assessment for the PMS group were compared with those of the non-PMS group. SETTING: RMIT teaching clinics. DATA ANALYSIS: The data collected were entered into a spread sheet and contingency tables were created. The data were analyzed by use of chi-squared tests, with the statistical significance being set at P < .05. RESULTS: The PMS group had a higher percentage of positive responses for each of 12 measured spinal dysfunction indexes except for range of motion of the low back. The indexes where the increase was statistically significant (P < .05) were cervical, thoracic, and low back tenderness, low back orthopedic testing, low back muscle weakness, and the neck disability index. An average of 5.4 of the 12 indexes were positive for the PMS group compared with 3.0 for the non-PMS group. CONCLUSIONS: A relatively high incidence of spinal dysfunction exists in PMS sufferers compared with a comparable group of non-PMS sufferers. This is suggestive that spinal dysfunction could be a causative factor in PMS and that chiropractic manipulative therapy may offer an alternative therapeutic approach for PMS sufferers.

Adolescent↗
PubMed1991

Instrumental straight-leg raising: a new approach to Lasègue's test.

In clinical practice the outcome of Lasègue's test is interpreted with respect to two variables: (1) the maximum angle between the leg and the horizontal plane to which the leg can be lifted, and (2) the pain that is provoked by the movement. For a number of reasons it is difficult in many patients to interpret the test outcome; predominantly, it is because of the lack of information it yields concerning the activity of the muscles. To get more information, an instrumental test was developed that imitates Lasègue's test. In this setup, which is based on a simple biomechanical model, the leg is passively raised in a lift installation. During lifting, the angles between leg and horizontal plane and between leg and pelvis are measured with electrogoniometers; the lift moment is determined with the help of a force transducer; pelvic rotation is assessed with a lordosis meter; and surface electromyography is used to record electric transducer; pelvic rotation is assessed with a lordosis meter; and surface electromyography is used to record electric activity in the erector spinae, the gluteus maximus, and the semimembranosus. The method, called instrumental straight-leg raising, makes it possible to determine the extensibility, elasticity, and electric activity of the hamstrings and back muscles during Lasègue's test. This information provides a better basis for the interpretation of the test outcome.

Adult↗
PubMed1986

Aftereffects in the responses of cat muscle spindles.

Responses have been recorded from primary endings of muscle spindles in the cat soleus muscle. Changes in spindle responsiveness were measured following a period of conditioning that consisted of a series of rapid stretches or of tetanic ventral root stimulation. In the testing procedure the response of a single spindle afferent was recorded to stimulation of a dynamic fusimotor axon during a slow stretch. Changes in gross afferent discharge coming from the muscle were measured by integrating the activity recorded in dorsal roots. If, after conditioning stretches, the muscle was immediately returned to its initial length, the spindle responded to the test fusimotor stimulation with a high-frequency burst of afferent impulses. If the muscle was held stretched for 3 s after conditioning the response to the brief test tetanus was small or "depressed." It has been suggested that conditioning stretches result in detachment of stable crossbridges in intrafusal fibers and that these bridges then reform over the next few seconds at whatever length the muscle happens to have at the time. When it is long, shortening the muscle back to the initial length leads to the development of slack in intrafusal fibers because of the passive stiffness they have acquired from the presence of the stable bridges. Under these conditions a brief test fusimotor tetanus will lead to a depressed response because the slack must first be taken up before a full response can be generated. It was possible to reverse the depression by interposing an extrafusal contraction during the period between the conditioning and test sequences. It is suggested that lateral compression from the contracting extrafusal fibers and the stretch they impose as they relax reduces any intrafusal slack and thereby reduces the depression. A more quantitative measure of intrafusal slack than the test for depression is to determine the delay in onset of the afferent response to a longer fusimotor tetanus. The delay was short a long initial muscle lengths where, if the muscle was left undisturbed, it soon disappeared completely and spontaneously. It is suggested that at long lengths passive tension in the muscle tends to remove any slack in intrafusal fibers and therefore removes any after effects. The rise in resting discharge of muscle afferents after a conditioning tetanus applied to the ventral root ("postcontraction sensory discharge") can be accounted for by the same hypothesis.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1999

Recovery from exercise-induced desaturation in the paraspinal muscles in idiopathic scoliosis.

STUDY DESIGN: A study using near-infrared light spectroscopy to measure recovery from exercise-induced desaturation in the paraspinal muscles of patients with idiopathic scoliosis. OBJECTIVES: To measure oxygenation of the paraspinal muscles and obtain differences between the convex and concave sides. SUMMARY OF BACKGROUND DATA: Authors of previous studies have reported that some patients experience pain on the convex side of the paraspinal muscles. The muscles on the convex side are more stretched and stressed than those on the concave side. The current authors investigated the degree of stress by measuring oxygenation and blood volume changes. METHODS: Paraspinal muscle spectral properties at L3 were investigated using near-infrared light spectroscopy. Thirty-six patients (8 men and 28 women) underwent this procedure. To assess a level of peripheral adaptations to exercise, the half-time of Oxyhemoglobin/Myoglobin recovery was measured, which indicates the recovery from energy deficit after exercise. RESULTS: The average half-time recovery on the convex side was 3.38 seconds (range, 1.5-5.5 seconds), whereas that on the concave side was 1.51 seconds (range, 0.7-4.0 seconds). The average difference between the convex side and the concave side was 1.87 seconds (range, 0.9-3.5 seconds). CONCLUSIONS: Half-time recovery on the convex side in the patients with idiopathic scoliosis was slower than that in healthy adults (P < 0.05). Half-time recovery on the concave side in such patients was faster than that on the convex side (P < 0.01). The authors consider half-time recovery an indication of back muscle stress.

Adult↗
PubMed2000

Mechanisms of action of lumbar supports: a systematic review.

STUDY DESIGN: A systematic review and meta-analysis of studies on the putative mechanisms of action of lumbar supports in lifting activities. OBJECTIVE: To summarize the evidence bearing on the putative mechanisms of action of lumbar supports. SUMMARY OF BACKGROUND DATA: A restriction of trunk motion and a reduction in required back muscle forces in lifting are two proposed mechanisms of action of lumbar supports. Available studies on these putative mechanisms of action of lumbar supports have reported contradictory results. METHODS: A literature search for controlled studies on mechanisms of action of lumbar supports was conducted. The methodologic quality of the studies was assessed. The evidence for the two proposed mechanisms of action of lumbar supports was determined in meta-analyses. RESULTS: Thirty-three studies were selected for the review. There was evidence that lumbar supports reduce trunk motion for flexion-extension and lateral bending, with overall effect sizes of 0.70 (95% confidence interval [CI] 0.39-1. 01) and 1.13 (95% CI 0.17-2.08), respectively. The overall effect size for rotation was not statistically significant (0.69; 95% CI -0. 40-4.31). There was no evidence that lumbar supports reduce the electromyogram activity of erector spinae muscles (effect size of 0. 09; 95% CI -0.41-0.59) or increase the intra-abdominal pressure (effect size of 0.26; 95% CI -0.07-0.59). CONCLUSION: There is evidence that lumbar supports reduce trunk motion for flexion-extension and lateral bending. More research is needed on the separate outcome measures for trunk motion before definite conclusions can be drawn about the work conditions in which lumbar supports may be most effective. Studies of trunk motion at the workplace or during specified lifting tasks would be especially useful in this regard.

Back Injuries↗
PubMed1998

Can it be predicted which patients with chronic low back pain should be offered tertiary rehabilitation in a functional restoration program? A search for demographic, socioeconomic, and physical predictors.

STUDY DESIGN: A prospective clinical trial was conducted that involved six groups of patients with chronic low back pain selected from a large cohort (N = 816). OBJECTIVES: To correlate pretreatment baseline variables with outcome parameters after treatment in a functional restoration program or in control programs, to identify possible factors predictive of the need for functional restoration. SUMMARY OF BACKGROUND DATA: Since the functional restoration program was first described, research has focused on identifying patients who will or will not benefit from such a program. The value of previous studies is limited, however, because predictive factors from a control group were not "subtracted." METHODS: Eight hundred sixteen patients with chronic low back disability were included. All had a structured medical examination, including various physical tests before participation in either a functional restoration program (n = 621) or shorter "control" outpatient programs (n = 144). A smaller group of the cohort (n = 51) had no treatment and served as a pure control group. Six groups were selected from the cohort: Three underwent an identical functional restoration program and three underwent different outpatient control programs. Several baseline demographic, physical, and socioeconomic variables were correlated to 1-year outcome parameters. RESULTS: Age, days of sick leave, connection to the work force, and back pain intensity, were significantly correlated to success 1 year after entry into the study in all groups, no matter what kind of treatment was administered. Back muscle endurance, sports activity, activity of daily living scores, and vibrations were of importance in some outcome parameters for success after functional restoration. Smoking was positively correlated to disability pension. Days of sick leave and, in functional restoration, ability to work were the only factors that were correlative with statistics for people who withdrew. CONCLUSIONS: Different factors can be identified as predictive of outcome in a functional restoration program, but most of these factors were also shown to predict success for shorter control outpatient programs or of no treatment.

Activities of Daily Living↗
PubMed2002

[Effectiveness and compliance to a center-based short rehabilitation program with a home-based program for chronic low back pain].

OBJECTIVES: To assess the effectiveness and compliance to a short center-based intensive rehabilitation program followed by a home-based program for chronic low back pain. METHODS: Open prospective study in patients with chronic low back pain. The program included five weekly meetings of 12 day. Followed by a home-based program consigned on a booklet. Evaluation of deficiencies (lumbar and radicular pains on an analog visual scale, Schöber Mac Rae test, distance finger-ground, Shirado test, Sorensen test), disabilities (Quebec functional index), and handicap (analog visual scale) were assessed at J0, five weeks, three months and one year. Compliance was assessed quantitatively (a number of exercises, duration of the meetings, numbers meetings per week) and qualitatively (semi-quantitative ordinal scale). Patient's global opinion on the effectiveness of the program was collected on a semi-quantitative ordinal scale. RESULTS: 60 patients (20 women), aged of 45 +/- 10,4 years, were included. Duration of the symptoms was 110 +/- 123 months. At five weeks, a significant improvement of all parameters was observed. This improvement was maintained at three months. At 12 months, there was no more significant improvement. Compliance to the program was 64,4%. 40.7% of the patient did not realize their exercises correctly. The majority gave up back muscle isometric reinforcement exercises. Score of Shirado test, Quebec index and EVA handicap were significantly different in the group realizing the home-base program. At one year, 79% of the patients regarded this program as useful. CONCLUSION: Although quantitative compliance with the home-based program can be considered as satisfactory, the effectiveness of this intensive rehabilitation program of lumbar decrease after three months. This can be explained by a fast deterioration of qualitative compliance. The effectiveness of a short supervised program between 3 and 6 months associated a more powerful message of motivation must be evaluated.

Adult↗
PubMed2004

Effect of static stretch on fatigue of lumbar muscles induced by prolonged contraction.

Low back pain (LBP) is believed to be the result of fatigue of the back extensor muscles induced by prolonged contraction. Although static stretch has been considered to promote recovery from such muscle fatigue by relaxation, little is known about the effect of stretch on muscle fatigue, especially in the back extensor muscles. The purpose of this study was to investigate the effect of static stretch on prolonged contraction-inducedfatigue of the back extensor muscles using electromyographic (EMG) spectral analysis in ten healthy volunteers. Bipolar surface electrodes were placed on the longissimus and the multifidus muscles. EMG signals were collected during two trials of a Sorensen trunk-holding test for two minutes, with a five-minute rest period between the two trials (control test). All subjects were asked to perform the same trials, with one-minute of static stretch and a four-minute rest period (stretch test). Maintaining the knees toward the chest in supine position resulted in static stretch. The median frequency (MF) was calculated using a spectrum analysis program, and the MF slope over time was computed by linear regression analysis, and normalized with the y-intercept. The decreasing rate of the normalized MF slope between two trials in two tests was compared. The decreasing rate of the normalized MF slope of the second trial was larger than that of the first trial in the control test (p < 0.05), but no significant difference was observed in the stretch test. The results indicated that static stretch had a significant effect on the recovery from fatigue of the back extensor muscles, since it influenced the decreasing rate of the normalized MF slope.

Adult↗
PubMed1992

Axial muscle EMG responses evoked by cutaneous flank nerves in the female rat: effects of spinal transection, steroid hormones, and anesthesia.

In the lateral longissimus muscle (LL) of ovariectomized, female rats anesthetized with low surgical doses of urethane (1.0 g/kg), cutaneous reflexes with similar EMG and response patterns could be elicited from CNS-intact rats and from rats 24 h after complete thoracic spinal cord transection. The probability of eliciting a response to contralateral cutaneous nerve stimulation alone is much lower in rats with complete spinal transections compared to CNS-intact rats. For both CNS-intact and spinal-transected rats, responses to ipsilateral cutaneous nerve stimulation had a shorter latency and required significantly less current on average than responses to contralateral stimulation. The respective currents for eliciting threshold responses to ipsi- and contralateral stimulation are less for CNS-intact than spinal-transected rats. For both CNS-intact and spinal-transected rats, responses to bilateral cutaneous nerve stimulation were inconsistent in the same animal from run to run. With the variability of response at this anesthetic level, no consistent effects of progesterone (acute, i.v.) or estrogen (acute, i.v. and pretreatment, s.c.) were observed in spinal-transected rats. Intravenous progesterone reduced early, unilateral responses in CNS-intact rats anesthetized with 1.0 g of urethane/kg. For both CNS-intact and spinal-transected rats, additional anesthesia during EMG recording produced a gradual decline in response magnitude which could be recovered with a modest increase in stimulus intensity. However, spinal-transected rats appear to require less anesthesia to reduce comparable responses. The results suggest that supraspinal input is especially effective for facilitating contralateral cutaneous reflexes in back muscles, whereas it contributes more equally with afferent input and segmental circuitry to the efficacy of ipsilateral cutaneous reflexes.

Anesthesia↗
PubMed1995

Functional morphology of indrid lumbar vertebrae.

Indrids are primarily vertical clingers and leapers but also engage to various extents in climbing, suspensory postures, bimanual movement, bipedal hopping, and quadrupedalism. It has been demonstrated that these behaviors are well reflected in the appendicular anatomy of these primates, while indrid vertebral anatomy has received relatively little attention. In this morphometric study, biomechanically relevant aspects of the lumbar vertebrae of Indri indri, Propithecus diadema, and Propithecus verreauxi were compared to those of Varecia variegata, a large-bodied predominantly pronograde and quadrupedal lemur. Results indicate that, compared to Varecia, the indrids have relatively shorter lumbar vertebral bodies, shorter lumbar regions, more dorsally projecting lumbar spinous processes, and more dorsally positioned lumbar transverse process tips. In addition, indrid lumbar spinous and transverse processes are oriented differently than those of Varecia. Overall, indrid lumbar vertebral morphology converges with that of hominoids, atelines, and possibly lorids, suggesting a lumbar adaptation to upright or "antipronograde" postures that require a reduction in spinal flexibility. The dorsally projecting spinous processes may be related to back muscle extensor power during leaping and/or the maintenance of upright postures. By contrast, the lumbar vertebrae of Varecia resemble those of primates and other mammals that have habitually pronograde postures and emphasize spinal flexibility in the sagittal plane during locomotion.

Animals↗
PubMed2002

Danger of damaging the medial branches of the posterior rami of spinal nerves during a dorsomedian approach to the spine.

Postoperative atrophy of the deep back muscles may be caused by denervation during a dorsomedian approach to the thoracolumbar spine; ensuing instability of the spine with poor clinical results, perhaps due to such muscle loss, has been observed in 11.7% of cases (Sihvonen et al., 1993, Spine 18:575--581). More specifically, this complication may be caused by damaging the medial branches of the posterior rami of the spinal nerves during lateral retraction of the muscles. To investigate the anatomic topography of the medial branches of the posterior rami of the spinal nerves, 18 carbol-formol-fixed specimens were dissected using an operation microscope; also, 3 fresh cadavers were cut in horizontal and vertical planes with a rotary cryotome to confirm the anatomic topography observed in the fixed specimens. In the thoracolumbar spine the medial branch of the posterior ramus of the spinal nerve is subject to ligamentous fixation by the strong fibers of the mammillo-accessory ligament, which extends between the mammillary process and accessory process infero lateral to the superior articular process. When the dorsomedian approach to the thoracolumbar spine is enlarged laterally to the articular processes by retracting the paraspinous muscles, the medial branches of the posterior rami of the spinal nerves are endangered. This may cause postoperative pain as well as dynamic instability beyond the corresponding segments. The results of our anatomic study suggest that the posterior surgical midline approach to the thoracolumbar spine should not be enlarged laterally to the articular processes to prevent injury to the medial branches of the posterior rami of the spinal nerves.

Dissection↗
PubMed2005

Meox1Cre: a mouse line expressing Cre recombinase in somitic mesoderm.

We developed a novel strategy based on in vitro DNA transposition of phage Mu to construct vectors for "knock-in" of the gene encoding Cre recombinase into endogenous loci in embryonic stem cells. This strategy was used to introduce Cre into the mouse Meox1 locus, which was expected to drive Cre expression in the presomitic and somitic mesoderm. In embryos heterozygous for both Meox1(Cre) and R26R or Z/AP reporter alleles, specific and efficient recombination of the reporter alleles was detected in the maturing somites and their derivatives, including developing vertebrae, skeletal muscle, back dermis, as well as endothelium of the blood vessels invading the spinal cord and developing limbs. In contrast to the somitic mesoderm, Cre activity was not observed in the cranial paraxial mesoderm. Thus, the Meox1(Cre) allele allows detailed fate-mapping of Meox1-expressing tissues, including derivatives of the somitic mesoderm. We used it to demonstrate dynamic changes in the composition of the mesenchyme surrounding the developing inner ear. Meox1(Cre) may also be used for tissue-specific mutagenesis in the somitic mesoderm and its derivatives.

Animals↗
PubMed2003

Osteogenecity of octacalcium phosphate coatings applied on porous metal implants.

The biomimetic route allows the homogeneous deposition of calcium phosphate (Ca-P) coatings on porous implants by immersion in simulated physiologic solution. In addition, various Ca-P phases, such as octacalcium phosphate (OCP) or bone-like carbonated apatite (BCA), which are stable only at low temperatures, can be deposited. In this pilot study, experiments were designed with a twofold-purpose: (1) to investigate the osteoinduction of OCP-coated and noncoated porous tantalum cylinders and of dense titanium alloy cylinders (5 mm in diameter and 10 mm in length) in the back muscle of goats at 12 and 24 weeks (n = 4); and (2) to compare the osteogenic potentials of BCA-coated, OCP-coated, and bare porous tantalum cylinders in a gap of 1 mm created in the femoral condyle of a goat at 12 weeks (n = 2). In the goat muscle, after 12 weeks the OCP-coated porous cylinder had induced ectopic bone as well as bone within the cavity of the OCP-coated dense titanium cylinder. In the femoral condyle, bone did not fill the gap in any of the porous implants. In contrast with the two other groups, OCP-coated porous cylinders exhibited bone formation in the center of the implant. The nature of the Ca-P coating, via its microstructure, its dissolution rate, and its specific interactions with body fluids, may influence the osteogenecity of the Ca-P biomaterial.

Animals↗
PubMed2005

Morphological variation of the thoracolumbar vertebrae in Macropodidae and its functional relevance.

The present study was designed to investigate how the form of the marsupial thoracolumbar vertebrae varies to cope with the particular demands of diverse loading and locomotor behaviors. The vertebral columns of 10 species of Macropodidae, with various body masses and modes of locomotion, together with two other arboreal marsupials, koala and cuscus, were selected. Seventy-four three-dimensional landmark coordinates were acquired on each of the 10 last presacral vertebrae of the 70 vertebral columns. The interspecific variations of the third lumbar vertebra (L3, which approximates the mean) and the transitional patterns of the thoracolumbar segments were examined using the combined approach of generalized Procrustes analysis (GPA) and principal components analysis (PCA). The results of analyses of an individual vertebra (L3) and of the transitional patterns indicate significant interspecific differences. In the L3 study the first PC shows allometric shape variation, while the second PC seems to relate to adaptation for terrestrial versus arboreal locomotion. When the L3 vertebrae of the common spotted cuscus and koala are included for comparison, the vertebra of the tree kangaroo occupies an intermediate position between the hopping kangaroo and these arboreal marsupials. The L3 vertebrae in the arboreal marsupials possess a distinct dorsoventrally expanded vertebral body, and perpendicularly orientated spinous and transverse processes. The results of the present study suggest that vertebral shape in the kangaroo and wallaroos provides a structural adaptation to hopping through a relatively enlarged loading area and powerful lever system. In contrast, the small-sized bettongs (or rat kangaroos) have a relatively flexible column and elongated levers for the action of back muscles that extend and laterally flex the spine. The complex pattern of vertebral shape transition in the last 10 presacral vertebrae was examined using PCAs that compare between species information about vertebral shape variation along the thoracolumbar column. The results reinforce and emphasize important aspects of the patterns of variation seen in the detailed analysis of the third lumbar vertebra. The results also imply that size, spinal loading pattern, and locomotor behavior exert an influence on shaping the vertebra. Further, the morphological adaptations are consistent within these marsupials and this opens up the possibility that this kind of analysis may be useful in making functional inferences from fossil material.

Animals↗
PubMed1992

Slow release of anticancer drugs from porous calcium hydroxyapatite ceramic.

We have developed a new delivery system for sustained release of an anticancer drug (cis-platinum) by enclosure into blocks of porous calcium hydroxyapatite ceramic. The slow release of this drug from this system was confirmed in in vitro experiments. When this system was implanted into normal back muscle, or the tibia, sustained release of cis-platinum was observed during a 12-week period after implantation. The diffusion rate of cis-platinum into blood and other organs (liver, kidney, brain) was less than 10% of that at the implanted site. This delivery system placed into experimental tumors of mice also showed a uniform release of anticancer drug for more than 3 months. Inhibition of tumor growth was more marked after local implantation of this system than after intraperitoneal administration of cis-platinum. These results indicate that this new approach to a drug delivery system may well have an important role in cancer chemotherapy. In bone tumors it is attractive because the mechanical strength of calcium hydroxyapatite ceramic permits partial surgical excision and replacement of the bone defect at the same time.

Animals↗
PubMed1992

The neuromuscular basis of hereditary kyphoscoliosis in the mouse.

We describe a new neuromuscular disorder in the kyphoscoliotic mouse mutant (ky). Mice were killed at ages from birth to 210 days, and tissues were taken for standard light microscopy, histochemistry, nerve ending studies, and electron microscopy. At birth a few myofibers showed phagocytosis ultrastructurally. Between 6 and 25 days there was prominent necrosis and regeneration in soleus, gracilis, paraspinal, and back muscles. At 47 days, these muscles were atrophic and necrosis and regeneration were rare. At 136 days, all muscle groups, including head muscles, showed some degree of myofiber atrophy and gracilis was fibrotic. Prominent intramuscular axonal sprouting was present from 31 days. Peripheral nerves and anterior horn cells were normal. The findings indicate a neuromuscular basis of hereditary kyphoscoliosis in the mouse. The animal may be useful as a model of human muscle disease and scoliosis.

Animals↗