Maximal strength training in patients with Parkinson's disease: impact on efferent neural drive, force-generating capacity, and functional performance.

Parkinson's disease (PD) is characterized by progressive neurological deterioration, typically accompanied by reductions in skeletal muscle force-generating capacity (FGC) and functional performance. Physical activity has the potential to counteract this debilitating outcome, however, it is elusive if high-intensity strength training included in conventional treatment may improve results. Therefore, we randomly assigned 22 PD patients (74 ± 9 yr) to conventional rehabilitation with or without maximal strength training (MST) performed as leg press and chest press at ~90% of one repetition maximum (1RM), five times per week for 4 wk. FGC, physical performance, and efferent neural drive assessed as evoked potentials (V-wave normalized to M-wave in m. soleus) were measured following training. Results revealed that only MST improved 1RM leg press (101 ± 23 to 118 ± 18 kg) and chest press (36 ± 15 to 41 ± 15 kg), plantar flexion maximal voluntary contraction (235 ± 125 to 293 ± 158 N·m), and rate of force development (373 ± 345 to 495 ± 446 N·m·s-1; all P < 0.05; different from controls P < 0.05). FGC improvements were accompanied by an increased efferent neural drive to maximally contracting musculature (V-to-M ratio: 0.17 ± 0.12 to 0.24 ± 0.15; P < 0.05; different from controls P < 0.05), improved physical performance (stair climbing: 21.0 ± 9.2 to 14.4 ± 5.2 s; timed up and go: 7.8 ± 3.3 to 6.2 ± 2.5 s; both P < 0.05), and self-perceived improvement in health (3.1 ± 0.5 to 2.6 ± 0.9) and social activities functioning (2.2 ± 1.0 to 1.5 ± 1.1; both P < 0.05). No changes were observed in the control group. In conclusion, this study shows that MST improves FGC, neuromuscular function, and functional performance and advocates that high-intensity strength training should be implemented as an adjunct therapy in the treatment of PD patients.NEW & NOTEWORTHY This randomized, controlled trial documents that supervised high-intensity strength training improves efferent neural drive, maximal muscle strength, rate of force development, and functional performance in patients with Parkinson's disease (PD). In contrast, no differences were observed in these outcome variables in patients receiving conventional treatment consisting of recreational physical activity with low-to-medium intensity. Consequently, this study advocates that high-intensity strength training should be implemented in the clinical treatment of PD patients.

The effect of exercise on fatigue and physical functioning in breast cancer patients during and after treatment and at 6 months follow-up: A meta-analysis.

Breast cancer is the leading cause of cancer in women worldwide. Exercise interventions may improve physical and psychological factors during and after active breast cancer treatment. The aim of this systematic review was to assess the current knowledge regarding the efficacy of physical exercise with respect to fatigue and self-reported physical functioning. Systematic searches in Cochrane Library, Medline, Embase, Cinahl, PsycINFO, AMED and PEDro. After assessing the quality of the studies, we identified 25 randomized controlled trials that included 3418 breast cancer patients. An increase in physical functioning and a decrease in fatigue were observed after a physical exercise intervention, with an SMD of 0.27 (0.12, 0.41) and -0.32 (-0.49, - 0.14), respectively. There were slightly higher improvements in physical functioning and fatigue when the patients received the intervention after adjuvant breast cancer treatment. The 6-month follow-up data showed a small favourable difference for the physical exercise group for both physical functioning and fatigue. This systematic review found that an exercise intervention program can produce short-term improvements in physical functioning and can reduce fatigue in breast cancer patients. However, more studies are needed to confirm the time-dependent observations in this study.

Measurement Properties of the Nordic Questionnaire for Psychological and Social Factors at Work: A Rasch Analysis.

The main aim of this study was to evaluate the measurement properties of the Nordic Questionnaire for Psychological and Social Factors at Work (QPS Nordic) and the domains of demand, control and support. The Rasch analysis (RUMM 2030) was based on responses from 226 subjects with back pain who completed the QPS Nordic dimensions of demand, control, and social support (30 items) at one year follow up. The Rasch analysis revealed disordered thresholds in a total of 25 of the 30 items. The domains of demand, control and support fit the Rasch model when analyzed separately. The demand domain was well targeted, whereas patients with current neck and back pain had lower control and higher support than reflected by the questions. Two items revealed DIF by gender, otherwise invariance to age, gender, occupation and sick-leave was documented. The demand, control support domains of QPS Nordic comprised unidimensional constructs with adequate measurement properties.

The effect from maximal bench press strength training on work economy during wheelchair propulsion in men with spinal cord injury.

OBJECTIVE: To assess the effect from maximal bench press strength training (MST) on wheelchair propulsion work economy (WE). STUDY DESIGN: Pretest-posttest case-control group design. SETTING: St Olavs Hospital, Trondheim, Norway. METHODS: Seventeen male individuals with spinal cord injury (SCI) paraplegia were allocated to either MST bench press (n=11) or the control group (CG) (n=7). The MST group trained bench press three times per week, for 6 weeks, starting at 85-95% of their pretest bench press one-repetition maximum (1RM). For calculation of WE during wheelchair propulsion, oxygen uptake (VO2) measurements were collected during wheelchair ergometry (WCE) at submaximal workload of 50 W. Similarly, peak oxygen uptake (VO2peak) and peak power output (W) were measured during WCE. RESULTS: Individuals in the MST regimen significantly improved WE compared with the CG by 17.3 % (mean between-group differences: 95% confidence interval) of 2.63 ml kg-1 min-1: (-4.34, -0.91) (P=0.007). Between pretest and posttest, the increase in bench press 1RM was by 17% higher in the MST group compared with the CG. At peak testing, the MST group generated significantly higher peak power compared with the CG. All other physiological variables were comparable within and between groups. CONCLUSIONS: A 6-week MST bench press regimen significantly improved WE during wheelchair propulsion at 50 W workload. These preliminary data support a possible beneficial role for MST to reduce the energy cost of wheelchair propulsion for SCI individuals.

Segmental mobility, disc height and patient-reported outcomes after surgery for degenerative disc disease: a prospective randomised trial comparing disc replacement and multidisciplinary rehabilitation.

This prospective multicentre study was undertaken to determine segmental movement, disc height and sagittal alignment after total disc replacement (TDR) in the lumbosacral spine and to assess the correlation of biomechanical properties to clinical outcomes.A total of 173 patients with degenerative disc disease and low back pain for more than one year were randomised to receive either TDR or multidisciplinary rehabilitation (MDR). Segmental movement in the sagittal plane and disc height were measured using distortion compensated roentgen analysis (DCRA) comparing radiographs in active flexion and extension. Correlation analysis between the range of movement or disc height and patient-reported outcomes was performed in both groups. After two years, no significant change in movement in the sagittal plane was found in segments with TDR or between the two treatment groups. It remained the same or increased slightly in untreated segments in the TDR group and in this group there was a significant increase in disc height in the operated segments. There was no correlation between segmental movement or disc height and patient-reported outcomes in either group.In this study, insertion of an intervertebral disc prosthesis TDR did not increase movement in the sagittal plane and segmental movement did not correlate with patient-reported outcomes. This suggests that in the lumbar spine the movement preserving properties of TDR are not major determinants of clinical outcomes.

Effect of leg vascular occlusion on arm cycling peak oxygen uptake in spinal cord-injured individuals.

STUDY DESIGN: Cross-sectional single-subject design. OBJECTIVES: To determine whether leg vascular occlusion (LEVO) augment arm cycling (ACE) peak oxygen uptake in spinal cord-injured individuals. SETTING: University Hospital, Norway. METHODS: Fifteen individuals with C(4) to T(12) spinal cord injury (SCI) were recruited and divided into two groups: injury above (SCI-high, n=8) or below (SCI-low, n=7) the T(6) level. Peak oxygen uptake (VO(2peak)) was measured during (1) ACE combined with LEVO, (2) ACE alone and (3) ACE combined with functional electrical stimulation cycling (FES hybrid cycling). RESULTS: In the SCI-high group, VO(2peak) and peak Watt during ACE with LEVO were higher than ACE alone: 20.0 (±5.0) versus 17.6 (±5.0) ml kg(-1) min(-1) (P=0.006), and 72.5(±32) versus 80.0 (±34) Watt (P=0.016), respectively. However, FES hybrid cycling VO(2peak) was significantly higher than ACE with LEVO: 24.4 (±4.1) versus 20.0 (±5.0) ml kg(-1) min(-1) (P=0.006). In the SCI-low group, there was no difference in VO(2peak) and related parameters between the three modalities. CONCLUSIONS: For spinal cord-injured individuals with injury level above T(6) (high) in the present study, LEVO combined with ACE augment VO(2peak). However, this acute increase in VO(2peak) was lower than when FES cycling was combined with ACE. These findings may have future implications for exercise prescription for spinal cord-injured individuals.

Force and stiffness of the pelvic floor as function of muscle length: A comparison between women with and without stress urinary incontinence.

AIMS: To compare passive and active mechanical properties in the pelvic floor as a function of tissue length in continent and incontinent parous women. MATERIALS AND METHODS: Twenty-four parous continent and 21 parous incontinent women were examined with an intravaginal device. Passive and active force/stiffness were measured by increasing the transverse diameter of the vagina. To allow a more accurate comparison between groups, measured forces were normalized with respect to bodyweight, that is, force/bodyweight. RESULTS: In both groups passive and active forces increased as a function of the increase in length of the pelvic floor tissues. No difference was found between the groups according to passive forces (P = 0.646), but active force was significantly higher (P = 0.030) in the continent group when normalized for bodyweight. There was an almost linear increase in normalized passive stiffness in the range tested. No differences were found between the groups (P = 0.855). Normalized active stiffness was significantly reduced in the incontinent group (P = 0.021). CONCLUSIONS: This study indicates that both active force development and active stiffness in the pelvic floor tissues are significantly reduced in incontinent women, whereas the passive resting mechanical forces in the pelvic floor tissues in both groups are not different.

Transforaminal steroid injections in the treatment of cervical radiculopathy. A prospective outcome study.

BACKGROUND: The aim of this study was to assess if transforaminal steroid injections applied to cohort of patients waiting for cervical disc surgery, reduce the pain of cervical radiculopathy and hence reduce the need for surgical intervention. Cervical radiculopathy due to cervical disc herniation or spondylosis is a common indication for cervical disc surgery. Surgery is however not always successful, and is not done without risk of complications. Transforaminal injection of steroids has gained popularity due to the rationale that inflammation of the spinal nerve roots causes radicular pain, and therefore steroids placed locally should relieve symptoms. METHODS: During a 12-month period, 21 secondary referral patients with unilateral cervical radiculopathy entered the study. Cervical disc herniation or spondylosis affecting the corresponding nerve root was demonstrated by appropriate investigation (MRI or myelography). The patients then received 2 transforaminal steroid injections, at 2 weeks interval, while waiting for operative treatment. The pain intensity (VAS), Odom's criteria and operative indications were registered at 6 weeks and 4 months. FINDINGS: After receiving injection treatment 5 of the 21 patients decided to cancel the operation due to clinical improvement. A statistically significant reduction (0.02) in radicular pain score was simultaneously measured. This corresponds well with the reduction in operative requirements since radicular pain is the main indication for operative treatment. The responders experienced a long-lasting effect. Those responding positively however improved neck pain to the same extent as radicular pain, and patients with cervical spondylosis responded as positively as those with disc herniation. INTERPRETATION: This prospective cohort study indicates a reduction in the need for operative treatment due to injection treatment. The clinical effect is measurable, and a statistically significant improvement of the radicular pain is registered. Routine transforaminal injection treatment prior to surgery seems rewarding, but the complication risk must be taken into consideration.

Force-length relationship in the pelvic floor muscles under transverse vaginal distension: a method study in healthy women.

AIMS: The purpose of this study was to investigate whether there is a relationship between changes in the diameter of the urogenital hiatus and force developed in pelvic floor musculature. In addition, we wanted to examine the reliability of the method that measures force development in the pelvic floor in the transverse direction of the urogenital hiatus. MATERIALS AND METHODS: Passive and total force in the pelvic floor was measured with an intra-vaginal device in 20 healthy parous volunteers. The measurements were done with a consecutively increasing diameter in the transverse plane of the urogenital hiatus. The procedure was repeated with a few days interval. RESULTS: The measurements show an increase in force with an increasing device-diameter. The results are reliable at all the diameters tested, estimated by the within-subject day-to-day variability which was non-significant. The 40 mm diameter device is most favourable, estimated by Bland Altman plots of the test-retest measurements. CONCLUSIONS: Force development in pelvic floor muscles increased as a function of vaginal diameter when measured in the frontal plane. The measurements were reliable at all the different diameters chosen.

Are fatigue and disturbances in pre-programmed activity of pelvic floor muscles associated with female stress urinary incontinence?

AIMS: To investigate whether there is a difference between a continent versus a stress urinary incontinent group of women regarding: (i) fatigue in pelvic floor muscles, and (ii) pre-activation times between pelvic floor and abdominal muscles during coughing. METHODS: Twenty-six continent and 20 stress urinary incontinent parous women were examined. Fatigue was measured with an intravaginal device. Time to 10% decline of the initial reference force (RF) was defined as time-to-fatigue. Simultaneous recordings of force developed in levator ani muscle and electromyographic activity in the external oblique abdominal muscle were performed to determine whether contraction of pelvic floor muscles precedes activity in abdominal muscles during coughing. RESULTS: Time-to-fatigue was identical in the two groups (10.5 sec in the continent and 11.5 sec in the incontinent group, median values). Normalized force was significantly reduced in the incontinent group. The pelvic floor muscles contracted 160 msec before the abdominal muscles in both groups. In 24% of the continent and in 30% of the incontinent women, however, abdominal muscle activity preceded activity of pelvic floor muscles. CONCLUSIONS: Muscular fatigue, defined as rate of force loss, does not seem to be associated with urinary stress incontinence. Moreover, muscular activity recruitment patterns were equal in both groups suggesting that other factors than disturbances of ordered muscle recruitment, that is, pelvic floor followed by abdominal muscles, may be responsible for stress urinary incontinence. It is likely that reduced normalized force, as found in the incontinent group, is an important contributing factor.

Vertebral height, disc height, posteroanterior displacement and dens-atlas gap in the cervical spine: precision measurement protocol and normal data.

OBJECTIVE: (1) Precise measurement of vertebral height, disc height, posteroanterior displacement and dens-atlas gap from lateral radiographic views of the cervical spine. (2) Compilation of a normative database for these parameters, specifying dependence on gender and age. DESIGN: Descriptive study, based on measurements from lateral radiographic views of the cervical spine of healthy subjects. BACKGROUND: Normal data of vertebral height, disc height, posteroanterior displacement and size of the dens-atlas gap as well as their biological range of variation and potential dependence on gender and age are not available. METHODS: Based on computer-aided measurements from lateral radiographic views of the cervical spine, a new protocol determines these parameters. RESULTS: are compensated for radiographic magnification, variation in stature and the individually adopted posture of the cervical spine; they are virtually uninfluenced by radiographic distortion and patient alignment errors. A specimen study as well as inter- and intra-observer studies quantify measurement errors.Results. Employing the new protocol, vertebral height C3-C7 and disc height C2/C3-C6/C7 are measured with relative errors of 3.9% and 5.7% respectively. Posteroanterior displacement C1/C2 to C6/C7 is measured with an error of 2.8% of mean vertebral depth and the dens-atlas gap is measured with an error of <1.8% of the depth of C2. A normal database for the dimensions of cervical vertebrae and discs as well as of the sagittal plane alignment of the vertebrae within the cervical spine is compiled from 135 lateral views of healthy adults. CONCLUSIONS: Vertebral height, disc height, posteroanterior displacement and size of the dens-atlas gap are measured with high precision. Normal data are presented for the first time. RELEVANCE: The new protocol in conjunction with the normal database enables future studies detecting or monitoring morphological effects of, for example, trauma, long-term high mechanical loading, disc degeneration, rheumatoid arthritis, fusion or other surgical interventions.

Sagittal plane segmental motion of the cervical spine. A new precision measurement protocol and normal motion data of healthy adults.

OBJECTIVE: (1) Precise documentation of sagittal plane segmental rotational and posteroanterior translational motion of segments C0/C1-C6/C7 of the human cervical spine from lateral radiographic views. (2) Compilation of a database describing normal motion. (3) Comparison of individual motion patterns with the normal database. DESIGN: Descriptive study based on computer-aided measurements from lateral radiographic views taken in flexion and extension. BACKGROUND: Previous studies concentrated on segmental rotational motion of the cervical spine. Normal data for translational motion were not available. Description of cervical spine motion patterns thus remained incomplete. METHODS: Based on computer-aided measurements from lateral radiographic views taken in flexion and extension, a new protocol determines rotational and translational motion for all segments (C0/C1-C6/C7) imaged on the radiographic views. Measured results are corrected for radiographic magnification and variation in stature; they are virtually uninfluenced by radiographic distortion and patient alignment errors. A database describing normal motion was compiled from 137 sets of lateral views of healthy adults taken in active flexion and extension. A specimen study as well as inter- and intra-observer studies quantify measurement errors. RESULTS: The error study demonstrated the error (SD) of a rotational motion measurement to amount to slightly less than 2 degrees. The error (SD) of a translational motion measurement amounts to less than 5% of vertebral depth; for a vertebra of 15 mm depth this corresponds to 0.7 mm. A normal database for rotational and translational motion was compiled. There was a linear relation between rotational and translational motion. This finding agrees qualitatively with results from previous studies; quantitative comparisons are not possible due to divergent definitions for translational motion. The relation between rotation and translation can be employed in individual cases to predict translational motion, in dependence on the rotation actually performed. A comparison of the rotational motion with the normal database and the difference between predicted and actual translational motion allow segmental hypo-, normal or hypermobility to be quantified. CONCLUSIONS: The new protocol measures segmental motion with high precision and corrects for radiographic distortion, variation in stature and alignment errors of patients. Thus, archive studies using existing radiographs are feasible. RELEVANCE: Flexion-extension radiographs of the cervical spine are performed to explore potential damage to the bony or ligamentous structure resulting in abnormal, segmental motion patterns. Determining rotational motion gives only an incomplete picture. The new protocol allows for precise quantification of translational motion and classification of segments as hypo- or hypermobile by comparison with normal motion data.

Do human lumbar discs reconstitute after chemonucleolysis? A 7-year follow-up study.

STUDY DESIGN: A retrospective, longitudinal study of 51 patients, covering a mean follow-up period of 81 months. OBJECTIVE: To observe the long-term temporal course of the height of human lumbar discs after chemonucleolysis. To document whether human lumbar discs reconstitute, thus characterizing the healing potential of central disc tissue. SUMMARY OF BACKGROUND DATA: Although reconstitution of disc height within some months of chemonucleolysis has been observed in animal experiments, human lumbar discs have shown no tendency to regain their initial height within 1 year of treatment. To date, there has been no report on longer follow-up periods. The different reactions of animal and human discs may be dose-related or related to differences in tissue properties, physiologic environment or in vivo loading conditions. METHODS: Using a new protocol, the heights of lumbar discs were measured from sets of lateral radiographic views of 51 patients subject to chemonucleolysis by treatment with chymopapain (doses of 4000 or 3000 picokatals [pkat]). The sets comprised a view taken before treatment, a view taken (on average) 4 months after treatment, and a view taken (on average) 81 months after treatment. In the majority of patients, untreated discs adjacent to discs treated with chemonucleolysis served as control discs. RESULTS: Shortly after injection of chymopapain, all treated discs decreased in height. The height decrease of treated discs amounted to 15.8% on average. In the subcohort treated with 4000 pkat, the loss did not reverse during the entire follow-up period; in the subcohort treated with 3000 pkat a small fraction of the lost height was regained. Untreated neighboring control discs showed a minor (3.4%) decrease in height. CONCLUSIONS: Human lumbar discs do not reconstitute after chemonucleolysis. Because the long-term temporal course of disc height in patients is in disagreement with observations from animal experiments, caution is suggested when generalizing results from animal studies to humans.

Assessment of sagittal plane segmental motion in the lumbar spine. A comparison between distortion-compensated and stereophotogrammetric roentgen analysis.

STUDY DESIGN: Sagittal plane translatory and rotatory motion was measured in 15 lumbar motion segments of 8 patients by distortion-compensated and stereophotogrammetric Roentgen analysis. OBJECTIVE: To compare measurement precision of the new distortion-compensated Roentgen analysis protocol with that of the established Roentgen stereophotogrammetric technique under realistic clinical conditions. SUMMARY OF BACKGROUND DATA: Roentgen stereophotogrammetric analysis constitutes the most precise method available to assess segmental motion. Because of the invasive nature of the procedure, however, there is interest in alternative, noninvasive protocols suitable for studying larger patient cohorts. METHODS: In 8 patients, segmental motion of 15 lumbar segments that had undergone previous spinal surgery was assessed from stereo views by using Roentgen stereophotogrammetric analysis. Sagittal plane segmental motion was assessed by distortion-compensated Roentgen analysis. Sagittal plane translatory and rotatory motion data obtained by both methods were compared. RESULTS: With respect to Roentgen stereophotogrammetric analysis, sagittal plane rotation was determined by distortion-compensated Roentgen analysis with an error (standard deviation) of 1.4 degrees and a mean difference of less than 0.05 degree. Sagittal plane translation was determined by distortion-compensated Roentgen analysis, with an error of 1.25 mm and a mean difference 0.5 mm. CONCLUSION: Measurement precision of distortion-compensated Roentgen analysis is slightly inferior to that of Roentgen stereophotogrammetric analysis but substantially higher than that of conventional protocols assessing lumbar segmental motion. If measurement precision is considered adequate and if a noninvasive technique is indicated, distortion-compensated Roentgen analysis can be used to provide reliable motion data required for epidemiologic and clinical studies.

Spinal shrinkage during work in a sitting posture compared to work in a standing posture.

OBJECTIVE: The objective was to measure the possible differences in shrinkage of the thoracolumbar spine in subjects working in a sitting and a standing posture for 6.5 h at work, in a realistic work environment. The isolated shrinkage of the thoracic and the lumbar spine was also examined. STUDY DESIGN: This study presents a new protocol to measure shrinkage of the thoracic and lumbar spine separately. BACKGROUND: Controversies still exist with regard to the load on the spine in a sitting compared to a standing position. Some report that shrinkage is greatest in the sitting position while others report the reverse. However, nothing is known about the height reduction of the thoracic and the lumbar spine during loading for 6.5 h in a real work environment. Therefore, the behaviour of the thoracic and the lumbar spine under practical condition has to be investigated. METHOD: A stadiometer with a measurement error of 0.51 mm was used to measure changes in spinal height during work. To exclude first-time behaviour of the spine, a pre-test lasting 50 min was undertaken. The mean of the last three measurements was used as the reference height. During work, height measurements of the spine were performed every 20 min. To separate the behaviour of the thoracic and the lumbar spine, two benchmarks were placed at the vertebrae prominens and at the thoracic-lumbar junction. Shrinkage of the spine was investigated within three different cohorts: (I) work in a sitting posture for 6.5 h; (II) relaxed sitting for 2 h vs work for 2 h in a sitting position and (III) work in a standing position for 6.5 h. RESULTS: Relaxed sitting leads to a gain in stature compared to work in a sitting position for 2 h. The major gain in stature occurred in the lumbar spine. Comparison of cohort (III) working in a standing position with cohort (I) working in a sitting position shows that the shrinkage of the spine is greatest when work is performed in a standing posture. The major differences were found in the shrinkage of the lumbar spine, e.g. shrinkage of the lumbar spine in the standing cohort (III) was 4.16 mm compared to 1.73 mm in the sitting cohort (I). CONCLUSIONS: There is a gain in stature during relaxed sitting compared to work in a sitting posture. The load on the spine is greatest when work in a standing position is performed. The greater shrinkage of the lumbar spine during work in a standing position compared to a sitting posture is probably due to: (i) differences in lumbar lordosis and (ii) the effect of bending and torsion while handling the work materials.

Precision measurement of segmental motion from flexion-extension radiographs of the lumbar spine.

OBJECTIVE: To measure sagittal plane motion of lumbar vertebrae from lateral radiographic views. Previously identified factors of imprecision such as distortion in central projection, off-centre position, axial rotation, and lateral tilt of the spine were compensated. STUDY DESIGN: This study presents a new protocol to measure sagittal plane rotational and translational motion from lateral flexion-extension radiographs of the lumbar spine. BACKGROUND: Conventional methods to determine sagittal plane rotation and translation are prone to error from the distortional effects of the divergence of the radiographic beam and the measurement error inherent in constructing tangents to the contours of the vertebral body. High precision is attained by roentgen-stereophotogrammetric methods, but because of their invasive nature they can be applied only in exceptional cases. Agreement has been reached only in that measurement of sagittal plane motion from lumbar spine flexion-extension radiographs is inaccurate. Normal patterns of sagittal plane motion and the definition of what is an abnormal flexion-extension radiograph have not been settled. METHOD: Starting from an analysis of vertebral contours in the lateral view, geometric measures are identified which are virtually independent of distortion, axial rotation or lateral tilt. Applying a new protocol based on those geometric measures, the pattern of translational and rotational motion was determined from flexion-extension radiographs of 61 symptom-free, adult subjects. Measurement errors were quantified in a specimen experiment; a reproducibility study quantified inter- and intraobserver errors. RESULTS: Magnitude and sign of 'translation per degree of rotation' determined from a cohort of 61 adult subjects were very uniform for all levels of the lumbar spine. An auxiliary study evaluating a cohort of 10 healthy subjects where flexion-extension radiographs had been taken standing and side-lying showed no dependence of the rotation/translation pattern on posture. The error study demonstrated errors in angle ranging between 0.7 and 1.6 degrees and errors in displacement ranging between 1.2% and 2.4% of vertebral depth (the largest errors occurring at the L(5)/S(1) segment). Intra- and interobserver tests showed no or only negligibly small bias and an SD virtually equal to the measurement error multiplied by radical2. The relation of displacement to angle observed in the normal cohort can be used in individual cases to predict translational motion depending on the rotation actually performed. A comparison of the predicted translation (determined from normal controls) and the value actually measured allows translational hypo-, normal, or hypermobility to be quantified. Examples illustrate application of the new method in cases of normal, hypo-, and hypermobility and in the case of an instrumented spine. CONCLUSIONS: The results of this study show that precision of the measurement of rotational and translational motion can be considerably enhanced by making allowance for radiographic distortional effects and by minimizing subjective influence in the measurement procedure.

Mechano-reception in osteoblast-like cells.

Response to mechanical stimulation is a basic biological phenomenon. Nearly all cells process mechanical input and respond to it by inducing and modulating biochemical pathways. In organisms with tissues, if the average mechanical load is increased, some tissues can increase their performance and often increase their bulk by cell division. A reduction in mechanical loading decreases performance, catabolic activity gains, and the tissue degenerates. The process of anabolism and catabolism regulated by mechanical loading is a second-to-second, minute-to-minute, and hour-to-hour process that works together with local and systemic hormones to ensure that the tissue can meet the demands of the mechanical environment. On the other hand, a mechanical load that is too high can cause tissue and matrix failure and damage to the cells, which can result in inflammation. In this paper, we review the possible biophysical and cell biological mechanisms that might be responsible for transducing physiological and hyperphysiological mechanical loading into the biological response of skeletal cells. We speculate on what the mechanism of mechano-transduction in bone might be compared with that of other cells and on how information produced by mechanical loading might be passed on to other cells to achieve a coordinated tissue response.

Changes in muscle fiber cross-sectional area and concentrations of Na,K-ATPase in deltoid muscle in patients with impingement syndrome of the shoulder.

Disturbances of the stabilizing musculature are an important factor in painful shoulders. The important changes in the rotator cuff muscles are well established, but less attention is put on possible disturbances of the deltoid muscle. This study investigated the effect of shoulder impingement on muscle fiber cross-sectional area and the Na,K-pump concentration of the deltoid muscle. The study included six patients with impingement syndrome. Biopsies were taken from the affected and unaffected sides. The muscle fiber cross-sectional area and the Na,K-ATPase concentration was measured. There were significant decreases (p < 0.05) in cross-sectional area of type 1 and type 2 fibers of the affected deltoid muscle of 25 and 18%, respectively. The Na,K-pump concentration of the affected muscles was reduced by 26.6% (p < 0.05).

Thigh muscle atrophy after femoral shortening. Vastus intermedius cross-section studied in osteotomized rats.

We determined the effect of a shortening/lengthening osteotomy on muscle fiber cross-sectional area in the vastus intermedius in 14 rats. The left femur was shortened 5 mm in half of the rats and elongated 5 mm in the other half. In both groups, the right femur was osteotomized and stabilized without shortening/lengthening. After 3 months, open biopsy specimens of the vastus intermedius were taken for measurements of the muscle cross-sectional area in both Type 1 and Type 2 fibers; 150 fibers were measured in each specimen. In the shortened group, the cross-section was reduced in both types of fibers. After lengthening, no differences in the fiber cross-sectional area were found. We conclude that differences in stretch and tension of the muscles are responsible for the atrophy after femoral shortening and the maintenance of the fiber cross-sectional area after lengthening.