Cohort study of occupational risk factors of low back pain in construction workers.

OBJECTIVES: To identify work related risk factors of future low back pain (LBP) in a cohort of construction workers free of LBP at the start of follow up. METHODS: The Hamburg construction worker study comprises 571 male construction workers who have undergone two comprehensive interview and physical examination surveys. A cohort of 285 subjects without LBP at baseline was identified. After a follow up of 3 years, the 1 year prevalence of self reported LBP was determined in the 230 men followed up (80.7%). Prevalence ratios (PRs) with 95% confidence intervals (95% CIs) of LBP at follow up according to self reported work tasks of construction workers measured at baseline were estimated from Cox's regression models which were adjusted for age, and anthropometric measures. RESULTS: At follow up 71 out of 230 workers (30.9%) reported LBP during the preceding 12 months. Four work tasks (scaffolding, erecting roof structures, sawing wood, laying large sandstones) with an increased risk of 1 year prevalence of LBP at follow up were further evaluated. After further adjustment for occupation the relative risk was increased for workers who had reported > or = 2 hour/shifts laying large sandstones (PR = 2.6; 95% CI 1.1 to 6.5). Work load of bricklayers was additionally estimated by an index on stone load (high exposure: PR = 4.0; 95% CI 0.8 to 19.8), and an index for laying huge bricks/blocks (yes/no: PR = 1.7; 95% CI 0.5 to 5.7). CONCLUSIONS: The results suggest that self reported differences in brick characteristics (size and type of stone) and temporal aspects of the work of bricklayers (average hours per shift laying specified stones) can predict the future prevalence of LBP. The data have to be interpreted with caution because multiple risk factors were tested.

Sacroiliac dysfunction in construction workers.

BACKGROUND: In the literature of manual medicine the sacroiliac joint is widely accepted as a potential source of low back pain. On the other hand, some investigations have detected sacroiliac joint dysfunction without concomitant low back pain. The prevalence of sacroiliac dysfunction in the population has been noted in the medical literature to be between 19.3% and 47.9%. However, the prevalence of sacroiliac dysfunction in the general population and for construction workers is unknown. OBJECTIVE: This article presents results from the Hamburg Construction Workers Study in respect to sacroiliac diagnostics. The prevalence of and connection between sacroiliac dysfunction and low back pain are particularly interesting. DESIGN AND PARTICIPANTS: The sacroiliac joint diagnostics were studied in a cross-section investigation of a cohort of 480 male construction workers. Manual examination is the standard in the diagnostics of sacroiliac joint conditions at present. The assessment of sacroiliac joint function by standing flexion test, the spine test, the iliac compression test, and the iliac springing test was operationalized as two categories: sacroiliac dysfunction I and II. RESULTS: A prevalence of 29.0% was found for dysfunction I and 6.3% for dysfunction II, whereas a prevalence of 7.9% was found for the coprevalence of low back pain and sacroiliac dysfunction on the day of examination. This study demonstrated no statistical associations between low back pain and sacroiliac joint dysfunction. CONCLUSIONS: The reason why symptomatic and asymptomatic sacroiliac dysfunctions exist has not yet been sufficiently explained. The identification of pain-provoking factors should be the aim of subsequent investigations. A further study with a prospective design will be necessary to answer the questions that remain.

Sacroiliac joint diagnostics in the Hamburg Construction Workers Study.

BACKGROUND: In the medical literature, test procedures for sacroiliac joint diagnostics are viewed as controversial. The provocation tests are based on provoked sacroiliac pain, whereas the palpation tests examine the motion of the sacroiliac joint or describe the condition indirectly if limitation of the sacroiliac function is present. It must be presumed that the use of different test results in the detection of varying functional phenomena of a sacroiliac dysfunction or, alternatively, that identical effects of a dysfunction are evaluated in differing ways. OBJECTIVE: This article presents results with regard to the consistency of tests for sacroiliac joint dysfunctions carried out on participants from the building trade. DESIGN AND PARTICIPANTS: The consistency of the tests (standing flexion test, spine test, iliac compression test, iliac springing test) used in a cross-section investigation of a cohort of 480 male construction workers is presented. To evaluate the degree of consistency of the test procedure the percentage agreement and the kappa value, including a confidence interval of 95%, are given. RESULTS: The consistency between the iliac compression test and the three sacroiliac palpation tests could not be shown to be statistically significant. The consistency between the three palpation tests was moderate to good and the percentage agreement was acceptable (87.4%, 88.6%, 80.9%). CONCLUSIONS: It may be assumed that the palpation tests characterize the same dysfunction of the sacroiliac joint. Standing flexion test, spine test, and iliac springing test seem to be valuable tools for sacroiliac joint diagnostics.

Construction work and low back disorder. Preliminary findings of the Hamburg Construction Worker Study.

STUDY DESIGN: Cross-sectional part of a longitudinal study in 571 male construction workers. OBJECTIVES: The Hamburg construction worker study is being conducted to assess the extent of musculoskeletal disorders in construction workers and factors predisposing for or leading to musculoskeletal disorders. The purpose of this analysis is to report findings about the association between job history and low back disorder. SUMMARY OF BACKGROUND DATA: Repetitive strain in forced positions during long periods of time has been reported as a risk factor for low back disorder. Of all construction workers, bricklayers predominantly are exposed to these conditions. METHODS: Subjects were recruited mainly from a routine health check-up. A structured interview with complete job history, job related activities, and symptoms was administered, and a detailed standardized physical examination was performed. Age-adjusted prevalences of low back pain were calculated, and logistic regression models were used to estimate odds ratios and their confidence intervals for different durations of working in a specific job category and physical signs of low back disorder, adjusting for a variety of possible confounders. RESULTS: The 12 month prevalence of low back pain was highest in painters (57%), intermediate in concrete builders and bricklayers (41%), and lowest in carpenters and unskilled workers (38%). The age-adjusted odds ratio (95% confidence interval) of low back disorder for having worked longer than 10 years as a bricklayer was 2.3 (1.2-4.5). CONCLUSIONS: Working longer than 10 years as a bricklayer was associated with signs of low back disorder. No comparable associations were found for house painters, carpenters, nor concrete builders. If replicated, these findings could be used to focus preventive measures on bricklayers with a long job history.

[A CAE (computer aided engineering) approach to dynamic whole body modeling--the forces iin the lumbar spine in asymmetrical lifting]. / Ein CAE-basierter Zugang zur dynamischen Ganzkörpermodellierung--Die Kräfte in der lumbalen Wirbelsäule beim asymmetrischen Heben.

Biomechanical models of the human body play an important role in the analysis of the mechanical loading of the musculo-skeletal system. The whole-body model presented in this paper is based on a CAE (Computer Aided Engineering) program that permits the dynamic simulation of complex systems of rigid bodies. The model we developed on this basis consisted of 19 segments and 18 joints. The experimental data are derived from the 3D motion analysis system VICON, which is provided with 5 cameras, a force-plate and a 10-channel EMG recorder. The kinematic data are fed into the simulator after first being processed in a special manner to generate drivers for joint angles. The model was first used to calculate the compression forces generated within the lumbar spine during the asymmetric lifting and putting down of a 15 kg stone. The quasistatic calculation shows a dynamic contribution to the compression forces generated during the lifting of 11%. Increasing or decreasing the inertial moments of the segments by the factor 2 had an effect of less than 1% with the identical movement.

Morbus de Anquin or spinous engagement syndrome. A rare cause of low-back pain syndrome and sciatica.

We report on a rare disease called to Anquin's disease or spinous engagement or impingement syndrome. Low-back pain in this specific syndrome probably combined with sciatica is caused by a hypertrophic spinous process along with a spina bifida occulta of the underlying vertebra. Mostly, the enlarged spinous process is seen at L5 and the spina bifida occulta at S1. Conservative therapy consists of physiotherapy with postural exercises including improvement of lumbar flexion. If conservative treatment is unsuccessful, surgical treatment is indicated. Surgical therapy should include resection of the hypertrophic spinous process, probably combined with revision of the nerve roots and division of adhesions. Between 1981 and 1993 six patients were treated surgically after long-lasting periods of conservative therapy. All patients were re-examined clinically and radiologically after a mean follow-up period of 2.9 years. In all but one patient a distinct release from lumbar back pain and/or sciatica was observed. Regarding this, the most important fact in de Anquin's disease is to be aware of this specific syndrome. If low-back pain can be traced to a hypertrophic spinous process the first choice of therapy should be conservative. In unsuccessful cases simple surgical resection probably combined with division of the adhesion can lead to significant release from pain and is recommended.

[ligament kinematics of the ankle joint. An experimental study]. / Bänderkinematik des oberen Sprunggelenkes. Eine experimentalle Untersuchung.

In an experimental study using osteo-ligamentous preparations of ankle joints we studied the ligamentous kinematics of isolated ligament fibers of different lateral and medial ankle ligaments. Results demonstrate a different kinematic pattern of the ligaments depending on the joint position. The anterior fibula-talar ligament shows an anisometric characteristic of different fibers and demonstrates a maximal ligament strain of the most anterior fiber in maximal plantarflexion; fibers located more dorsally have their maximal strain in plantarflexion of less degrees. In contrast to that the fibula-calcaneus ligament demonstrates a more isometric characteristic. At the medial side the different parts of the deltoid ligament also demonstrate a different kinematic characteristic. In contrast to the pars tibio-calcanearis which has a more isometric ligament kinematic of isolated fibers, ligament fibers of the pars tibiotalaris posterior demonstrate an anisometric ligament kinematic. For clinical aspects an anatomically correct reconstruction of ruptured ligaments and fractures as well as an anatomic reconstruction in chronic unstable ankle joints is recommended.

Bilateral osteochondritis dissecans of the medial trochlea femoris: an unusual case of patellofemoral pain.

We report a case of bilateral osteochondritis dissecans of the medial trochlea femoris. Arthroscopic removement of loose bodies in the symptomatic left knee led to an excellent result; the untreated right knee showed effusion and locking one year later. This condition should be considered in the diagnosis of patellofemoral pain.

[Synthetic replacement of the anterior cruciate ligament--effects on the remaining ligament structures]. / Synthetischer Ersatz des vorderen Kreuzbandes--Auswirkungen auf die verbleibenden Bandstrukturen.

In a three-dimensional anatomical knee joint model all major ligaments were replaced by six nylon fibers and length-pattern changes registered and computed during motion between 0-140 degree. Then anteromedial, posteromedial and intermedial fibers were replaced by an artificial ligament made from Aramid (one to three bundle prothesis) and length changes of the remaining ligaments investigated. The result revealed a dynamic feed-back with characteristic changes in the posterior and collateral ligaments in comparison to the reference. A synthetic replacement using a one bundle prothesis in the isometic tracking led to disapointing results. Best correlations were achieved mimicking the anatomic situation by use of a three bundle prothesis with nearly no changes in the length pattern of the remaining ligaments.

[Design of partial pelvic replacement with calculation of stresses on the pelvic bone using the finite element method]. / Konzipierung eines Beckenteilersatzes mittels Berechnung der Belastungen am Beckenknochen mit der Methode der Finiten Elemente.

Although tumors of the pelvic region are relatively rare, with regard to the provision of an individual prosthesis, they make great demands both on the engineer and on the surgeon. In the case of partial pelvic replacement, the main problem is that of fixation. The direction of the preload by the screw and counternut in the anchorage should make possible the introduction of forces into the bone that closely mimic the natural pre-operative situation, in order to keep bone remodeling and stressing to a minimum. A three-dimensional finite element (FE) analysis of the stresses at work in the pelvic bone was performed using an FE model of the pelvis constructed on the basis of computed tomographic data, since with the FE method it is possible to obtain information about deformations, internal stresses and local forces acting on the bone. The results show that the main stressing of the bony pelvis occurs in the region of the acetabulum and the iliosacral joints, and that further points of loading are located in the lower region of the ischium-and this while standing on one leg, on the side of the supporting leg.

[Primary diagnosis and postoperative course follow-up of inflammatory bone lesions of the spine. Conventional roentgen diagnosis and/or computerized tomography?]. / Primärdiagnostik und postoperative Verlaufs-kontrollen entzündlicher Knochenläsionen der Wirbelsäule. Konventionelle Röntgendiagnostik und/oder Computertomographie?

This paper presents a comparison of the diagnostic value of CT studies and conventional radiological diagnosis, based on 46 CT studies, in patients with inflammatory bone lesions of the spine (n = 20) before and after surgical interventions (n = 12). In cases with a tentative clinical diagnosis of an inflammatory bone lesion, CT will not supplant conventional radiological diagnosis as the roentgenologic method of first choice. The superiority of CT is based on its ability to demonstrate intraspinal, paravertebral, and intervertebral complications. Osseous incorporation of spongiosa parts and the healing of paravertebral and intraspinal complications can be assessed more easily and accurately with CT.

Computer-aided three-dimensional reconstructions of the arrangement of primary spermatocytes in human seminiferous tubules.

With the use of a digital image-processing method three-dimensional reconstructions of the arrangement of spermatocytes in human seminiferous tubules were performed. With this method it was possible to investigate the cellular distribution in the tubule in nearly any given perspective and projection. In addition, by means of simple mathematical procedures, such as by transformation of Cartesian coordinates into cylindrical coordinates, it was possible to vary the shape of a reconstruction, i.e., to convert the cylindrical image of a tubular portion into a right-angled r-phi-z-representation. The present work not only confirms the existence of a complex helical plan of organization of the human seminiferous epithelium but also provides further aspects of the phenomenon of physiological germ-cell loss and its integration into the kinetics of spermatogenesis.

Comparison of computed tomography and digital subtraction angiography of preoperative evaluation of soft-tissue tumors of the limbs.

The preoperative results of computed tomography (CT) (n = 59) and digital subtraction angiography (DSA) (n = 14) were compared with the intraoperative site and the pathological histological finding. The tumor was correctly estimated by CT in 69% (difference less than 20%), and overestimated in 31% (difference greater than 20%). The superiority of CT consisted in the visualization of intratumor alterations and the representation of the muscle compartments concerned and of the spatial relationship of the tumor to the bone and large vessels. Specific morphological CT criteria were found only in rhabdomyosarcoma and liposarcoma. Unequivocial preoperative appraisals with regard to the histological finding to be expected were possible only in the case of lipoma. DSA was helpful for evaluation of vascular involvement and vascularization. The technique contributed to differential diagnosis (malignant-benign) in only 70%. In peripheral soft-tissue tumors (lower leg, forearm), arterial DSA is preferable to venous DSA. Angiography should be employed after the CT investigation and reserved for specific cases.

Organization and morphogenesis of the human seminiferous epithelium.

The various types of human primary spermatocytes were classified by means of morphological and morphometrical studies. Based on this classification, the topographic arrangement of the spermatocyte populations in the longitudinal course of seminiferous tubules was determined. This analysis revealed human spermatogenesis be to subjected to a complex local plan of organization, which is based upon the geometry of spirals. The centers of gravity of spermatocyte populations of subsequent degrees of differentiation are arranged on helices that are contracted conically to the lumen of the seminiferous tubule. On these helices the centers of gravity of the populations diverge continuously 173.8 degrees +/- 32.4 degrees. Populations of the same degrees of development are arranged on helices with constant diameters. On these helices the centers of gravity of the populations diverge continuously 142.6 degrees +/- 14.2 degrees. The present results lead to new aspects of the kinetics and morphogenesis of the seminiferous epithelium, which can be integrated into a comprehensive biological concept.

[Visco-elasticity and cell volume density of the patellar cartilage]. / Viskoelastizität und Zellvolumendichte des Patellaknorpels.

The elasticity of the joint surface was measured at defined points on a freshly removed patella which had no macroscopically apparent degenerative changes. The chondrocyte volume density of the stressed points was determined planimetrically. A correlation was found between the cell volume density and the viscoelastic properties of the joint cartilage, indicative of an increase in elasticity where the cell volume density was reduced. The mean chondrocyte volume under a defined joint surface was found to be almost constant, with varying cartilage thickness.

Morphometrical studies on the symmetry of the human knee joint: femoral condyles.

The curvature of the tibial part of the femoral condyles in the sagittal plane can be described by mathematical spirals: involutes of a circle. Archimedean and logarithmic spirals. In the order of the accuracy of measurement (+/- 0.2 mm) the curvature can be described by all three spirals.