Gunnar Németh

Karolinska Institutet, Orthopaedic Surgery, Emeritus

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MD, PhD, MBA. Experience from healthcare as researcher, surgeon, executive manager and board member. Pan-European experience as executive manager and consultant. Research profile is electromyography, biomechanics, clinical spine studies and health related quality of life. Published about 100 original peer reviewed papers.

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Papers by Gunnar Németh

Influence of sitting postures on neck and shoulder e.m.g. during arm-hand work movements

by Karin Harms-ringdahl and Gunnar Németh

Clinical Biomechanics, 1987

The aim of the study was to analyze the effect of different sitting postures on the level of acti... more The aim of the study was to analyze the effect of different sitting postures on the level of activity in some neck and shoulder muscles in a standardized work cycle involving movement of the arm/hand. Ten experienced female workers volunteered in a laboratory study. Full-wave rectified, low-pass filtered, time-averaged and normalized e.m.g. was used. Surface electrodes were applied unilaterally at six locations. The course of the level of muscle activity during the standardized work cycle is presented. There was a tendency to higher level of activity when the arm/hand was moving along the high part of the work object compared to along the low part. The level of activity during the standardized work movement with the arm/hand was significantly influenced by the sitting postures chosen. The highest activity levels were found in the posture with the whole spine flexed. A marked reduction of the level of activity was obtained when a posture with the thoraco-lumbar spine slightly inclined backward was used.

Differences in EMG-activity between patients with shoulder instability and normal controls

Journal of Biomechanics, 1989

European Spine Journal, 2006

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Load moment, muscle strength and level of muscular activity during internal rotation training of the shoulder

by Karin Harms-ringdahl and Gunnar Németh

Scandinavian journal of rehabilitation medicine. Supplement

Existing studies of shoulder joint loading, muscle strength and muscular activity do not, from th... more Existing studies of shoulder joint loading, muscle strength and muscular activity do not, from the point of view of clinical application, adequately cover these factors, knowledge of which is important for the design of optimal exercises for training shoulder impairments. In the present study, exercises using a weight-and-pulley device have been analysed in order to map the resistance moments of force in relation to the muscular strength capacity of shoulder internal rotators , and to map the activation of these muscles in response to the resistance from the device. The relationships established in the study provide a basis for optimising various types of shoulder training exercises. For example, an angle of 40 degrees between frontal plane and shoulder-pulley line has been found to give the best adaptation of resistance to strength. The study also demonstrates the possibility of using a pulley apparatus for shoulder inward rotator muscle training.

The axis of rotation of the ankle joint

by Gunnar Németh and Arne Lundberg

The Bone & Joint Journal

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[Pain analysis is vital in rheumatic diseases. The pain is often the patient's worst problem]

by Ralph Nisell and Gunnar Németh

Läkartidningen, Jan 11, 1998

The article consists of a synthesis of a rheumatic pain symposium held at the annual meeting of t... more The article consists of a synthesis of a rheumatic pain symposium held at the annual meeting of the Swedish Medical Association in 1996. Various aspects of pain in rheumatic diseases were discussed, such as physiological, neurohumoral and neurogenic mechanisms, sensory stimulation treatment, differentiation of mechanical and inflammatory pain, quality enhancement by improved cooperation between primary and tertiary care facilities, pharmacological treatment with (centrally and peripherally acting) opioids, selective cyclo-oxygenase inhibitors, and NMDA (N-methyl-D-aspartate) receptor antagonists. The aim of the symposium, with its focus on the manifest pain problem, was to improve our knowledge and skill in the understanding and treatment of this large patient category. For patients with rheumatic disorders exacerbated by pain problems, as for other patients, a pain diagnosis is of fundamental importance. This can be achieved by analysis of the social, psychological, physiological a...

Load on knee joint structures and muscular activity during lifting

by Ralph Nisell and Gunnar Németh

Scandinavian Journal of Rehabilitation Medicine

The load on the knee joints during lifting has been less studied than low back load. Healthy subj... more The load on the knee joints during lifting has been less studied than low back load. Healthy subjects lifted a 12.8-kg box from floor to table-level in three different ways; 1) with straight knees, 2) with bent knees and the box in front of the knees, and 3) with bent knees and the box between the knees. The loading moment of force about the bilateral knee axis was calculated by means of a computerized static sagittal plane model. Electromyography was recorded from quadriceps and ischiocrural muscles. The beginning of the flexed-knee lifts caused a flexing loading knee moment of about 50 Nm and a knee angle of 90 degrees. Straight-knee lifts gave all through the lift an extending loading moment. During the final phase of all lifts there was an extending loading knee moment of about 55 Nm and a knee angle of 0 degrees. The three lifts were compared and discussed from a biomechanical and ergonomical point of view.

Knee load and muscle activity during exercises in rising

Scandinavian journal of rehabilitation medicine. Supplement, 1983

Knee joint loading and the level of knee muscle activation during rising exercises have been eval... more Knee joint loading and the level of knee muscle activation during rising exercises have been evaluated and methods have been developed for such studies. Floor-to-foot forces were recorded using a force-measuring platform. The loading moment of force representing the resistance for the knee joint was calculated. It was shown that the initial knee loading moment with much flexed knees was high at large knee angles. The loading moment showed a marked decrease with decreasing knee angles. For small knee angles there was no resistance to knee extension. Muscular activity level was studied using EMG. The levels of activity in the quadriceps muscles were high at large knee angles and low at small angles. The hamstrings and gastrocnemius showed only low activity. The magnitude of change in knee extension resistance due to adaptive adjustment of the exercise device was mapped. These rising exercises will increase strength mainly for large knee angles and only for quadriceps muscles.

SKELETAL KINEMATICS OF THE ANTERIOR CRUCIATE LIGAMENT DEFICIENT KNEE WITH AND WITHOUT FUNCTIONAL BRACES

Steinmann traction pins were implanted into the femur and tibia of six subjects having a partial ... more Steinmann traction pins were implanted into the femur and tibia of six subjects having a partial or complete anterior cruciate ligament (ACL) rupture. Patients jumped for maximal horizontal distance and landed onto their deficient limb with the knee braced and unbraced. Tibiofemoral rotations and translations showed a general trend across subjects, i.e. skeletally based curves were similar in shape and

Methodological concerns using intra-cortical pins to measure tibiofemoral kinematics

Knee Surgery, Sports Traumatology, Arthroscopy, 2003

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Joint Motions of the Lower Limb During Ergometer Cycling

by Ralph Nisell and Gunnar Németh

Journal of Orthopaedic & Sports Physical Therapy, 1988

ABSTRACT

Influence of interelectrode distance and force level on the spectral parameters of surface electromyographic recordings from the lumbar muscles

Journal of Electromyography and Kinesiology, 2002

In order to study the influence of interelectrode distance and force level on the electromyograph... more In order to study the influence of interelectrode distance and force level on the electromyographic (EMG) spectral parameters and on their reliability, bipolar surface EMG measurements were performed on the lumbar muscles of 15 subjects. Two test contractions (45 s) at 40% of maximal voluntary contraction (MVC) were performed, one with 2 cm interelectrode distance and the other with 4 cm, followed by two contractions at 80% MVC with the same change in interelectrode distance. Increasing the interelectrode distance from 2 to 4 cm caused a significant mean decrease (about 8%) in the initial median frequency. It is shown that this shift is of an order of magnitude that may be expected from the bipolar electrode filter factor, and we further conclude that the observed individual variations in the shift are likely to be connected to fluctuations in the shape of the power spectrum and to variations in conduction velocity. No significant change was found for the median frequency slope when changing the interelectrode distance. Increasing the force (from 40 to 80% MVC) also caused a significant mean decrease (about 10%) in the initial median frequency. The median frequency slope became significantly more negative by more than 200%. We conclude, however, that torque fluctuations during the fatigue contractions should have had only minor influence on the standard error of measurement of the initial median frequency and of the median frequency slope.

Reliability of EMG spectral parameters in repeated measurements of back muscle fatigue

Journal of Electromyography and Kinesiology, 1999

The change in median frequency of the power spectrum of the electromyographic (EMG) signal may be... more The change in median frequency of the power spectrum of the electromyographic (EMG) signal may be used as a measure of muscle fatigue. The reliability of the median frequency parameters was investigated for EMG-recording sites at L1 and L5 right and left on the erector spinae. The reliability of subjective fatigue ratings of the back muscles (Borg CR-10 scale) and of maximal trunk extension torque (MVC) was also investigated. Eleven subjects with healthy backs performed a 45-s isometric trunk extension at 80% of MVC twice a day, on three different days. Two-factor analysis of variance was made to obtain the different variances from which the standard error of measurement (SEM) and the intra class correlation coefficient (ICC) were calculated. The SEM within-day was somewhat lower than that between-days. Both were about the same at all four electrode sites. The 95% confidence interval for the studied variables was for the initial median frequency +/- 10 Hz, for the slope +/- 0.4-0.5%/s, for the MVC +/- 36 Nm and for the Borg ratings +/- 1.6. We conclude that, with the presently used method, changes or differences within these limits should be regarded as normal variability. The slope may be of limited value because of its large variability. Whether the low intraclass correlation coefficient for the EMG parameters in the presently studied test group implies a low potential in discriminating subjects with back pain can not be decisively concluded.

Between-days reliability of subjective and objective assessments of back extensor muscle fatigue in subjects without lower-back pain

Journal of Electromyography and Kinesiology, 2000

It is important to evaluate the reliability of common used methods of examining muscle fatigue fr... more

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Self-administered examination versus conventional medical examination of the musculoskeletal system in the neck, shoulders, and upper limbs

Journal of Clinical Epidemiology, 1995

A self-administered examination protocol of the musculoskeletal system in the neck, shoulders, an... more A self-administered examination protocol of the musculoskeletal system in the neck, shoulders, and upper limbs was mailed to 350 subjects and the results were compared to those of a subsequent medical examination. The prevalences of reported positive findings were higher than in the medical examination. Validity ranged between poor and good. Acceptable validity was noted for items measuring tenderness. No systematic substantial exposure-related misclassification was noted. Self-administered examination of the musculoskeletal system is not suitable to replace a traditional medical examination in epidemiological studies. Self-administered examination of tenderness could, however, be used as a screening method in analytical studies of relations between exposure and disorders in the musculoskeletal system. Subjects reporting such findings at a self-administered examination could be further examined by professional examiners for definite diagnostic appraisal. Substantial savings in medical examination resources could thereby be obtained.

Surgery for herniation of a lumbar disc in Sweden between 1987 and 1999

The Journal of Bone and Joint Surgery, 2004

The National Inpatient Register and the Swedish Death Register were linked to determine the incid... more The National Inpatient Register and the Swedish Death Register were linked to determine the incidence of surgical intervention, the trends and characteristics of the patients, the death rate and the pre- and post-operative admissions for herniation of a lumbar disc based on comprehensive national data between 1987 and 1999. There were 27,576 operations which were followed cumulatively for 155,249 years, with a median of 6.0 years. The mean annual rate of operation was 24 per 100,000 inhabitants, the median age of the patients was 42 years. The 30-day death rate was 0.5 per 1000 operations. The rates of re-operation at one and ten years were 5% and 10%, respectively, decreasing significantly (40%) with time. The mean length of stay decreased from nine to five days. Patients who had been in hospital because of a previous spinal disorder had a significantly higher risk of readmission.

A model predicting individual shoulder muscle forces based on relationship between electromyographic and 3D external forces in static position

Journal of Biomechanics, 1998

To study the potentiality for developing an EMG-based model for the human shoulder, mapping of re... more To study the potentiality for developing an EMG-based model for the human shoulder, mapping of relations between static hand forces and electromyographic (EMG) activity of 13 shoulder muscles, were performed. The procedure was to perform by the hands slowly varying isometric forces up to 20% maximum voluntary force in the three-dimensional space. By combining these data with literature values on muscle physiological cross-sectional area and moment arm data, an EMG-based model was developed for estimating muscle forces in the glenohumeral joint. The model was validated for one standardized position by comparing joint moment, calculated from EMG by using the model, with moments from the external force. The highest correlation between these moments was found assuming a linear EMG/force calibration at low force level (&lt; 20% MVC), giving correlations from 0.65 to 0.95 for the abduction/adduction moment and from 0.70 to 0.93 for the flexion/extension moment, for the six subjects. Moments calculated from EMG were for most subjects somewhat lower than the moments from the external force; the mean residual error ranged from 1.6 to 9.9 Nm. Taking this into account, the results can be used for assessment of muscle forces based on recordings of external forces at the hands during submaximal static work tasks without substantially elevated arms.

Spinal stenosis re-operation rate in Sweden is 11% at 10 years—A national analysis of 9,664 operations

European Spine Journal, 2005

Re-operation rates in spinal stenosis surgery vary between 5 and 23%. Most previous studies have ... more Re-operation rates in spinal stenosis surgery vary between 5 and 23%. Most previous studies have been based on selected patients groups. We analysed the 10-year lumbar spinal stenosis re-operation rate from comprehensive Swedish national data during 1987-1999. The mean length of stay decreased from 2 weeks in 1987 to 1 week in 1999. Of 9,664 patients, 628 (6.5%) were re-operated. Within 30 days after the first spinal stenosis operation, 0.15% of the parients were re-operated. The 1-, 2-, 5-, and 10-year reoperation rates were 2, 5, 8 and 11%, respectively. The rate lowered by 31% over time. Adding a fusion may lower the re-operation risk, an observation which can only be evaluated in randomised trial.

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