Clinical symptoms related to musculoskeletal neck-shoulder pain and mobility in the cervico-thoracic spine.

In a cross-sectional study 142 male and 139 female workers participated in a self-report questionnaire and a clinical examination. The aim of this study was to use the cervico-thoracic ratio (CTR), a clinical method for measuring segmental mobility between C7 and T5, to evaluate the influence of segmental mobility in neck-shoulder pain and different subjectively experienced symptoms. The study showed that reduced relative mobility at levels C7-T1 and T1-T2 significantly predicted neck-shoulder pain and the symptom weakness in the hands. The strongest relationship between segmental mobility and symptoms was found among subjects classified as having an inverse C7-T1 function, defined as equal or less mobility in motion segment C7-T1 compared to T1-T2. Reduced mobility explained 14% of neck-shoulder pain and 15% of weakness in the hands. It is suggested that deviation from synchronous distribution of mobility between motion segments C7-T1 and T1-T2 might be a factor provoking joint mechano receptors.

Reduced mobility in the cervico-thoracic motion segment--a risk factor for musculoskeletal neck-shoulder pain: a two-year prospective follow-up study.

The aim of this study was to evaluate the variations in C7-T1 mobility in order to decide whether inverse C7-T1 function, defined as equal or less mobility in motion segment C7-T1 compared with T1-T2, could be used for prediction of neck-shoulder pain (NSP). One hundred and sixty-one female laundry workers participated in a prospective two-year follow-up study which included a self-report questionnaire and clinical examinations. The present study showed that the incidence of inverse C7-T1 function was 33% per year and subjects classified as having an inverse C7-T1 function three or more times during the follow-up period had an elevated risk of NSP (RR 3.1, CI 95% 1.1-6.9). According to the authors' interpretation, lack of synchronous mobility distribution between adjacent motion segments might be a provoking factor. Inverse C7-T1 function predicts NSP related to the cervico-thoracic articulations and yields a positive predictive value of 84%. Assessments must be repeated, however.

Mobility in the cervico-thoracic motion segment: an indicative factor of musculo-skeletal neck-shoulder pain.

The aim of the study was first to evaluate whether mobility in the cervico-thoracic motion segment is an indicative factor of musculo-skeletal neck-shoulder pain and secondly to compare differences in individual factors between cases and controls for female and male subjects. One-hundred-and-forty-two male electricians and 139 female laundry workers participated in a cross-sectional study. An examination of the Cervico-Thoracic Ratio and a classification of mobility at level C7-T1 was done. All subjects answered a questionnaire about musculo-skeletal complaints. The analysis of relationship between relative flexion mobility in motion segments C7-T5 and neck-shoulder pain showed significant relationships between mobility in specific motion segments and neck-shoulder pain. The overall fit of the multiple regression analysis explained 10% of the variation in neck index (N1) for subjects classified as hypomobile at level C7-T1 and 18% for subjects classified as having an inverse C7-T1 function. Both female and male subjects classified as hypomobile at level C7-T1 showed elevated odds ratios of 2.7 and 2.2, respectively, to have had more than 7 days of neck pain during the previous 12 months, compared to subjects classified as having ordinary mobility at level C7-T1. The factor age showed that young subjects with hypoar hypermobility at level C7-T1 showed elevated odds ratios for neck pain compared to subjects with ordinary mobility in the same age group. In old subjects hypermobility at level C7-T1 was protective compared to subjects with ordinary mobility in the same age group. The factor number of working years showed significant difference between cases and controls among female subjects in the ordinary and hypermobile classes. The factor height showed no significant differences between female or male cases and controls; it did show significant correlation to C7-T1 mobility among female subjects, but not among male subjects. The factors exercise and smoking showed significant differences between cases and controls among female subjects in the ordinary mobility class. The conclusion was that relative flexion mobility is a factor related to the development of neck-shoulder pain rather than the cause of pain.

A clinical method for measuring segmental flexion mobility in the cervico-thoracic spine and a model for classification.

Pain and limitation of spinal mobility are symptoms frequently reported by patients. Many methods have been used to assess the total range of mobility in the different parts of the spine, but there is no method for clinical examination of segmental mobility. The aim of this study was to describe such a technique concerning of segmental flexion mobility in the cervico-thoracic spine, C7-T5, and to present a model for classification of mobility. The results of this study show that the relative flexion mobility examined, according to the Cervico-Thoracic-Ratio technique (CTR), may become a valuable complement to conventional methods of assessing mobility in the cervical spine. The normalized CTR values are less influenced by the individual factors age, body weight, height and number of years at work and the classification model presented makes functional analysis of segmental flexion mobility in the cervico-junction and upper thoracic spine more substantial.

A clinical method for measuring the distribution of segmental flexion mobility in the cervico-thoracic spine.

The aim of this study was to evaluate the validity and the repeatability of a new technique to assess segmental flexion mobility in the cervico-thoracic spine between segments C7 and T5. The new technique is referred to as the Cervico-Thoracic-Ratio (the CTR-technique). The radiological evaluation of skin distraction measurements showed that validity was high for the CTR-technique. A high correlation between vertebral flexion mobility and skin distraction was recognized individually and for the whole group. The evaluation of repeatability was found to be high for intratester and fair for intertester repeatability. The CTR-technique may become a valuable complement to other methods for assessing segmental flexion mobility in patients suffering from neck-shoulder pain in clinical practice.

Evaluation of impact loading in overhead work using a bolt pistol support.

This paper evaluates the effects of a bolt gun support stand on impact loading of the hand-arm system while firing spiked bolts into a steel beam. Ten healthy male subjects fired two bolts into the centre of the beam, one with and one without the aid of the support stand. During firing of a bolt gun, the shock sequences were recorded by two accelerometers. The analysis showed that peak values of acceleration decreased more than eightfold during firing with the bolt pistol support. The shock damping effect due to the bolt support was noted at the thumb (metacarpal level) and elbow bones.

Implementation of double-pulsed holography in evaluation of whole-body vibration.

This study used a unique holographic technique to evaluate the effects of vibration on soft tissues and bones. It was possible to record forced whole-body vibration in humans by holograph interferometry using a double-pulsed ruby laser. The study investigated the manner in which the muscles of the back and vertebral column are affected by vibrations applied to the human buttocks in the sitting position. The subject was exposed to vibration at two frequencies: 40 and 60 Hz (vertical Z axis). Transmission of the vibrations along the subject's back was recorded by means of double-pulsed holography and electromyography. Evaluation of the vibration pattern showed that the vibrations are transmitted along the back all the way up to the neck and head. The pattern of vibration in the muscles of the back and vertebral column showed that the greatest effect was exerted on the lumbar region of the back and the area of transition between the thoracic and cervical regions.

Effects of vibration on arm and shoulder muscles in three body postures.

The electromyographic responses of arm and shoulder muscles to vibrations were studied in three postures similar to the postures of drilling in a ceiling, drilling in a wall and drilling in a floor. This experiment was performed within the defined parameters of: vibrational frequency at 30 Hz, acceleration level 40 m.s-2 (rms), pushing force expressed as percentage maximal voluntary contraction, and gripping force which was set at 100 N. The exposure time for each test was 5 min. The general findings from these three body postures show that all the examined muscles were affected by exposure to vibration. The EMG index increased as follows: trapezius muscle 39% (p less than 0.05), lower-arm flexor muscles 23% (p less than 0.05), infraspinatus muscle 14% (p less than 0.05), lower-arm extensor muscles 14% (p less than 0.1) and biceps muscle 6% (p less than 0.1). The muscle most affected by vibration was found to be the trapezius muscle. It should be taken into consideration that vibration can be a contributing factor in neck/shoulder disorders among power handtool operators. The general conclusion from this study is that changes in working posture give different transmissions of vibration in the upper extremities. It seems as if the prime movers and muscles with an increased muscle length or increased degree of contraction are most affected by vibration.