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Biomedical subjects

J Dvorak

Publications and source records attributed to J Dvorak.

At least 73 records · Page 4Linked to original sources
PubMed2000

Severe injuries in football players. Influencing factors.

The aims of this prospective study were to analyze factors related to the occurrence of severe football injuries in players of different ages (14 to 42 years) and different skill levels (local teams to first league teams). In the Czech Republic, 398 players were followed up for 1 year, during which time they sustained 686 injuries. Of these, 113 (16.5%) were severe injuries. Ninety-seven severe injuries (86%) were able to be documented in detail. Trauma was the cause of 81.5% of the injuries and overuse was the cause of 18.5%. Joint sprains predominated (30%), followed by fractures (16%), muscle strains (15%), ligament ruptures (12%), meniscal tears and contusions (8%), and other injuries. Injuries to the knee were most prevalent (29%), followed by injuries to the ankle (19%) and spine (9%). More injuries occurred during games (59%) than in practice. Twenty-four percent of the injured players had suffered a previous injury of the same body part. Forty-six percent of injuries were caused by contact and 54% involved no body contact. Thirty-one percent of severe injuries were caused by foul play. From these results and the analysis of injuries in specific body parts, the following factors were determined to influence the occurrence of severe injuries: 1) personal factors (intrinsic): age of player, previous injuries, joint instability, abnormality of the spine, poor physical condition, poor football skills, or inadequate treatment and rehabilitation of injuries; 2) environmental factors (extrinsic): subjective exercise overload during practices and games, amount and quality of training, playing field conditions, equipment (wearing of shin guards and taping) and violations of existing rules (foul play).

Adolescent↗
PubMed2000

Risk factor analysis for injuries in football players. Possibilities for a prevention program.

Review of the literature shows that information concerning risk factors for football injuries is incomplete and partly contradictory. The aim of this study was to analyze the influence of medical history, physical findings, football skills, and football performance, as well as psychosocial characteristics on the occurrence and severity of football injuries. The prospective outline of the study was as follows: after a baseline examination was performed to ascertain possible predictors of injury, all players were followed up weekly for 1 year to register subsequent injuries and complaints. Two hundred sixty-four of 398 players (67%) had complete weekly follow-ups over 1 year. A majority of the players (N = 216; 82%) were injured during the observation period. In comparing injured and uninjured players, several differences were observed. To create a multidimensional predictor score for football injuries, 17 risk factors were selected. These risk factors covered a wide spectrum, such as previous injuries, acute complaints, inadequate rehabilitation, poor health awareness, high life-event stress, playing characteristics, poor reaction time, poor endurance, and insufficient preparation for games. By summing up the individual risk factors, a predictive sum was calculated for each player. The more risk factors present at the baseline examination, the higher the probability of that player incurring an injury in the ensuing year. Using two risk factors as the cut-off score, more than 80% of the players were correctly classified as to whether they went on to incur an injury. Based on these findings, knowledge from the literature, and practical experience, possibilities for a prevention program are suggested.

Adolescent↗
PubMed2000

Medical history and physical findings in football players of different ages and skill levels.

The physical and physiologic demands of football on its participants become more pronounced as the level of competition increases. The aim of this study was to compare the medical history and physical findings in players from different levels of play as well as to analyze the relationship between pathologic findings in the joints of the lower extremities and the medical history. Five hundred eighty-eight football players from eight age and skill levels were investigated. The medical histories of the players were obtained by questionnaire. A physical examination conducted by specially trained physicians incorporated anthropometric and body fat measurements and examination of the spine and the hip, knee, foot, and great toe joints. On average, the players reported 6.6 (SD, 8.8) previous injuries. At the time of the examination, 136 players (24%) still felt the effects of a previous injury. Almost one-quarter of the players (134, 23%) had a pathologic finding in either the right or left knee, and even more players (162, 28%) had a pathologic anterior drawer sign either in the right or left ankle. A correlation was found between the location of the pathologic findings and the preferred leg for playing football. We recommend that further research should address the prevalence of pathologic findings and complaints in football players as well as the secondary structural changes that may occur as the result of playing football.

Adolescent↗
PubMed1999

A randomized clinical trial of three active therapies for chronic low back pain.

STUDY DESIGN: A randomized clinical trial. OBJECTIVES: To examine the relative efficacy of three active therapies for chronic low back pain. SUMMARY OF BACKGROUND DATA: There is much evidence documenting the efficacy of exercise in the conservative management of chronic low back pain, but many questions remain regarding its exact prescription and method of application. The most successful method must be identified to enable refinement of future rehabilitation programs to target the specific needs of the patient with chronic low back pain and the budget of the healthcare provider. METHODS: One hundred forty-eight patients with chronic low back pain were randomized to one of the following treatments, which they attended twice a week for 3 months: 1) modern active physiotherapy, 2) muscle reconditioning on training devices, or 3) low-impact aerobics. Pretherapy and posttherapy, objective measurements of lumbar mobility were performed, and questionnaires were administered inquiring about self-rated pain and disability, and psychosocial factors. Similar questionnaires were administered 6 months after therapy. The data were analyzed using the intention-to-treat principle. RESULTS: Of the 148 patients, 16 (10.8%) dropped out of the therapy. One hundred thirty-seven questionnaires (93%) were available for analysis at all three time points. After therapy, significant reductions were observed in pain intensity, frequency, and disability; Fear-Avoidance Beliefs about physical activity (FABQactivity); and "praying/hoping," "catastrophizing," and "pain behavior" coping strategies--each with no group differences in the extent of the response. These effects were maintained over the subsequent 6 months, with the exception of disability and FABQactivity for the physiotherapy group. There were small but significant posttherapy increases in lumbar mobility, with aerobics and devices showing a greater response than physiotherapy. CONCLUSION: The general lack of treatment specificity suggests that the main effects of the therapies were educed not through the reversal of physical weaknesses targeted by the corresponding exercise modality, but rather through some "central" effect, perhaps involving an adjustment of perception in relation to pain and disability. The direct costs associated with administering physiotherapy were three times as great, and devices four times as great, as those for aerobics. Administration of aerobics as an efficacious therapy for chronic low back pain has the potential to relieve some of the huge financial burden associated with the condition.

Adult↗
PubMed1999

[Manual therapy in lumbo-vertebral syndromes].

Based upon the shortly presented survey among the members of the Swiss Medical Association for Manual Medicine, the low back pain problems are approached by the means of manual therapy on average 805 times per year and physician. On average each case with low back pain is treated 1,4 times by a general practitioner with experience in manual medicine while specialists who are dealing with more complex cases on average 4 to 5 times. The functional disorders of the lumbar spine treated by manual therapy are superior to the physiotherapy approach or in comparison with a "placebo group" (information by general practitioner about low back pain and application of medication). An appropriate indication for manual therapy is relevant to avoid or reduce the possible risk of the treatment procedure. The physician who performs the manual therapy has to know the limits of the method. Also the knowledge of contraindications for manual therapy will reduce the incidence of possible complication. However based upon the survey among the swiss association the side effects and complications due to manual therapy of the lumbal spine are extremely seldom.

Humans↗
PubMed1999

Histology of the ligamentum flavum in patients with degenerative lumbar spinal stenosis.

The degree of calcification as well as the structural changes of the elastic fibres in the ligamentum flavum in patients with degenerative lumbar spinal stenosis were evaluated and the results were compared to those of patients without spinal stenosis. In 21 patients (13 male, 8 female) with lumbar spinal stenosis the ligamentum flavum was removed, histologically processed and stained. The calcification, the elastic/collagenous fibre ratio as well as the configuration of the fibres were evaluated with an image analyzing computer. As a control group, 20 ligaments of 10 human corpses were processed in the same way. The results were statistically analysed using the Mann-Whitney-Wilcoxon test (alpha = 0.05) and the t-test (alpha = 0.05). Nearly all the ligaments of patients with lumbar spinal stenosis were calcified (average 0.17%, maximum 3.8%) and showed relevant fibrosis with decreased elastic/collagenous fibre ratio. There was a significant correlation between age and histological changes (P<0.05). In the control group we only found minimal calcification in 3 of 20 segments (average 0.015%). No relevant fibrosis was found and the configuration of elastic fibres showed no pathologic changes. The results of this study illustrate the important role of histological changes of the ligamentum flavum for the aetiology of lumbar spinal stenosis.

Adult↗
PubMed1999

Relation between neuropsychological and neuroimaging findings in patients with late whiplash syndrome.

OBJECTIVES: The interpretation of long term cognitive impairment after whiplash injury is still a problem for many physicians. On the grounds of nuclear medicine findings previous research speculated that brain damage is responsible for cognitive problems of patients with whiplash. To test this hypothesis the relation between neuroimaging and neuropsychological findings was analysed. METHODS: Twenty one patients (11 women, 10 men, mean age 42.2 (SD 8.6) years) with the late whiplash syndrome (average interval of trauma 26.1 (SD 20.7) months) referred for diagnostic action to the Department of Neurology were investigated. Assessment included computer assisted assessment of working memory and divided attention, neuroimaging (by the means of [99mTc]-HMPAO-SPECT, [15O]-H2O-PET and [18F]-FDG-PET), testing of emotional functioning (depression and anxiety ratings), and pain intensity at the time of testing. RESULTS: On average, scoring on tests of cognitive functioning was very low. However, no significant correlations were found between regional perfusion or metabolism in any brain area and the scores of divided attention or working memory. By contrast, significant relations were found between indices of impaired emotional functioning (state anxiety) and divided attention. In addition, low scoring in divided attention was significantly correlated with pain intensity at the time of testing. CONCLUSIONS: The present data do not provide evidence of a significant relation between detectable morphological or functional brain damage and impaired cognitive performance in the late whiplash syndrome. Results indicate triggering of emotional and cognitive symptoms on the basis of initial injury of the cervical spine.

Adult↗
PubMed1998

Translaminar screw fixation of the lumbar and lumbosacral spine. A 5-year follow-up.

STUDY DESIGN: In a retrospective study, the long-term results of translaminar facet screw fixation of the lumbar and lumbosacral spine are reviewed. OBJECTIVES: To evaluate the clinical results, fusion rates and complications of this posterior fusion technique in various conditions of the lumbar spine. SUMMARY OF BACKGROUND DATA: Posterior fusion of the lumbar and lumbosacral spine is one of the possible methods to relieve pain and eliminate instability in degenerative conditions. Data in the literature support the use of internal fixation to optimize the rate of fusion. METHODS: Posterior lumbar and lumbosacral fixation with translaminar screws and fusion in 173 patients with degenerative changes with or without compressive syndromes including failed back syndromes, monosegmental hypermobilities, and posttraumatic conditions were investigated. Fixation and fusion with translaminar screws was performed in 57% monosegmentally, in 40% across two segments and in 2% over three segments. Decompressive surgery was performed in addition in 52% and nucleotomy in 30% of the cases. Clinical and radiologic assessment with flexion/extension x-rays was performed in 145 (83%) patients by two independent orthopedic surgeons. After an average follow-up of 68 months (range, 52-83). RESULTS: Ninety-four percent of the patients showed solid bony fusion in the radiologic follow-up. Loosening of the screws was noted in 3%, and two screws were broken without apparent motion on the functional x-rays. Pain scores decreased from 7.6 before surgery to 2.9 after surgery on a 10-point pain scale. The results were further analyzed according to Stauffer and Coventry with 99 good results, 70 satisfactory results, and 4 bad results. CONCLUSIONS: Translaminar screw fixation offers an immediate postoperative stability of the lumbar and lumbosacral spine and enhances fusion. In the present series no neurologic complications were noted. It represents a useful and inexpensive technique for short segment fusion of the nontraumatic lumbar and lumbosacral spine.

Adult↗
PubMed1998

[Sacral block: indications and effectiveness].

It has been shown that during injection of 17 to 20 ml local anesthetics combined with a corticosteroid via the hiatus canalis sacralis that the solution is distributed up to the level of the thoraco-lumbar junction. The indication for therapeutical peridural injection are radicular symptoms as a result of disc herniation, foraminal stenosis as well as neurogenic claudicatio. Contraindications are anticoagulation, local infection as well as suspicion of systemic inflammatory disease of the peripheral nervous system. With proper technique and adequate desinfection, complications and side effects are very rare.

Anesthesia, Epidural↗
PubMed1998

Simulation of whiplash trauma using whole cervical spine specimens.

STUDY DESIGN: Whiplash injuries were studied in an experiment using whole cervical spine specimen. OBJECTIVES: To develop a whiplash trauma model that uses a whole cervical spine specimen, and to show the feasibility and unique features of such a model. SUMMARY OF BACKGROUND DATA: Whiplash trauma has been simulated in biomechanical experiments using volunteers, whole body cadavers, animals, anthropometric dummies, and mathematic models. These experiments require large facilities, are expensive, and provide limited information about cervical spine injuries. METHODS: An alternate approach, in which a bench-top sled accelerating apparatus is used to produce whiplash trauma, has been developed to study such trauma in whole cervical spine specimens. Several transducers were developed to monitor soft tissue injuries during the trauma. The model also provides quantification of injuries to the cervical spine. RESULTS: To assess the feasibility and usefulness of the model, a specimen was traumatized, and the following parameters were monitored during the trauma: linear acceleration of the sled, linear and angular acceleration of the head surrogate, displacements of the head surrogate, loads at T1 and C1 vertebrae, and linear deformations of capsular ligaments and vertebral artery. CONCLUSIONS: This model, which incorporates a fresh cadaveric whole human cervical spine specimen, can simulate whiplash trauma effectively and is useful in providing a comprehensive set of clinically relevant information during the trauma. This model gives insight into the complex events and interactions that cause the injuries that occur during whiplash trauma.

Cadaver↗
PubMed1998

[Biomechanics of whiplash injury].

The article reports a new hypothesis of whiplash injury based on a series of experimental studies using isolated human cadaveric specimens. Although the clinical symptoms of whiplash are widely known, the understanding of the underlying injury mechanism is poor. The prevailing view of neck-hyper-extension as the essential injury mechanisms was not supported by recent experiments. In a series of experiments using eight human cadaveric specimens which underwent experimental stepwise whiplash acceleration from 2.5 to 10.5 g functional radiographs and flexibility tests were performed at the end of each acceleration step. Ligament strains, vertebral alignment and elongation of the vertebral artery were monitored during the whiplash trauma by highspeed cinematography and specially designed transducers. After the trauma CT- and MRI-scans were taken and specimens were sectioned using Cryomicrotomy. We found a distinct biphasic kinematic response of the cervical spine to whiplash trauma. In the first phase the spine formed an S-shaped curve with flexion at the upper levels and hyper-extension at the lower levels. This phase was found to be the vulnerable phase of whiplash trauma. The largest dynamic elongation of the capsular ligaments was observed at the C6-C7 level during this initial S-shaped phase of whiplash. The maximum elongation of the vertebral artery could be observed synchronously in the first S-shaped curve of the cervical spine. In the second phase of whiplash all levels of the cervical spine were extended, so that the head reached is maximum extension. No injuries were observed in the second phase. We propose, based on our experimental findings, that with low accelerations the anterior structures of the lower cervical spine are injured during the first phase of whiplash, when the cervical spine forms an S-shaped curve and before the neck is fully extended. At higher trauma accelerations there is also a tendency for the injuries to occur at upper levels of the cervical spine. Based on our findings the traditional view of whiplash as hyper-extension injury can be modified by a differentiated, time dependent, biphasic biomechanical model of the injury, thus allowing better and more effective injury prevention, diagnosis and therapy.

Biomechanical Phenomena↗
PubMed1998

Head kinematics during in vitro whiplash simulation.

Knowledge of precise head kinematics during whiplash trauma is important for identifying possible injury mechanisms and their prevention. This study reports a comprehensive data set describing head kinematic response to horizontal accelerations simulating whiplash. Seven isolated fresh human cervical spine specimens (C0 to T1 or C7), each carrying a surrogate head designed to represent a 50th percentile human head, were mounted on the sled and subjected to incremental trauma by horizontal sled accelerations of 2.5, 4.5, 6.5, 8.5, and 10.5 g. Sled and head kinematics were measured with potentiometers and accelerometers. The incremental sled accelerations resulted in average (standard deviations) sled velocity changes (delta V) ranging from 5.8 (0.2) to 15.8 (0.2) km/h. Generally, all the peak head kinematic parameters increased with increasing sled acceleration, except for the peak head angular displacement, which decreased. In the initial phase of a whiplash trauma, the head translated posteriorly with respect to T1, without rotation. In the later phase, the head rotated backwards, but much less than its physiological limit. Maximum head rotation of 31.5 (23.9) degrees occurred in a 2.5 g trauma class, and this was less than the maximum physiological head extension of 55.1 (13.3) degrees. Head kinematics expressed in the T1 or shoulder coordinate system is better suited to study potential neck injury in whiplash.

Accidents, Traffic↗
PubMed1998

PET with 18fluorodeoxyglucose and hexamethylpropylene amine oxime SPECT in late whiplash syndrome.

BACKGROUND: Many patients have cognitive abnormalities and psychological problems after whiplash injury to the cervical spine. To our knowledge, neuroradiologic imaging has not depicted brain damage that explains the symptoms. Parietotemporo-occipital perfusion deficits on hexamethylpropylene amine oxime (HMPAO) SPECT studies have been described among patients who have sustained whiplash injury. METHODS: We examined 13 patients with typical late whiplash syndrome (study group) using HMPAO SPECT, 18fluorodeoxyglucose (FDG) PET, and MRI of the brain and compared the findings with those for 16 control subjects who underwent FDG PET. RESULTS: In the study group, statistical parametric mapping revealed significantly decreased FDG uptake in the frontopolar and lateral temporal cortex and in the putamen. The frontopolar hypometabolism correlated significantly with scores of the Beck Depression Inventory. However, in individual cases, reliability in the depiction of hypometabolic areas was relatively low. No alterations were found in the parietotemporo-occipital area. In these areas, decreased uptake of HMPAO and FDG correlated with cortical mass. CONCLUSION: FDG PET did not allow reliable diagnosis of metabolic disturbances for individual patients. Therefore, we do not recommend FDG PET or HMPAO SPECT as a diagnostic tool in routine examinations of patients with late whiplash syndrome.

Adult↗
PubMed1997

Whiplash produces an S-shaped curvature of the neck with hyperextension at lower levels.

STUDY DESIGN: A bench-top trauma sled was used to apply four intensities of whiplash trauma to human cadaveric cervical spine specimens and to measure resulting intervertebral rotations using high-speed cinematography. OBJECTIVES: To determine the cervical spine levels most prone to injury from whiplash trauma and to hypothesize a mechanism for such injury. SUMMARY OF BACKGROUND DATA: Whiplash injuries traditionally have been ascribed to hyperextension of the head, but other mechanisms such as hypertranslation also have been suggested. METHODS: Six occiput to T1 (or C7) fresh cadaveric human spines were studied. Physiologic flexion and extension motions were recorded with an Optotrak motion analysis system by loading up to 1.0 Nm. Specimens then were secured in a trauma sled, and a surrogate head was attached. Flags fixed to the head and individual vertebrae were monitored with high-speed cinematography (500 frames/sec). Data were collected for 12 traumas in four classes defined by the maximum sled acceleration. The trauma classes were 2.5 g, 4.5 g, 6.5 g, and 8.5 g. Significance was defined at P < 0.01. RESULTS: In the whiplash traumas, the peak intervertebral rotations of C6-C7 and C7-T1 significantly exceeded the maximum physiologic extension for all trauma classes studied. The maximum extension of these lower levels occurred significantly before full neck extension. In fact, the upper cervical levels were consistently in flexion at the time of maximum lower level extension. CONCLUSIONS: In whiplash, the neck forms an S-shaped curvature, with lower level hyperextension and upper level flexion. This was identified as the injury stage for the lower cervical levels. A subsequent C-shaped curvature with extension of the entire cervical spine produced less lower level extension.

Biomechanical Phenomena↗
PubMed1997

Atlantoaxial fusion and retrodental pannus in rheumatoid arthritis.

STUDY DESIGN: This study analyzed the influence of atlantoaxial fusion in rheumatoid arthritis patients on inflammatory retrodental pannus. OBJECTIVES: To determine the value of fusion on the magnitude of pannus as a compressive structure on the spinal cord. SUMMARY OF BACKGROUND DATA: Transverse and vertical instability may lead to neurologic deficits from spinal cord compression. Increased size of the retrodental pannus can exacerbate the neurologic deterioration. Anterior removal of dens and pannus followed by posterior fusion has been proposed in such situations as a method to relieve spinal cord compression. METHODS: Twenty-two patients with atlantoaxial instability and verified pannus on magnetic resonance imaging underwent posterior fusion of the upper cervical spine. These patients were followed 12 to 75 months after surgery by clinical, radiologic, and magnetic resonance imaging evaluations. The size of the pannus was compared before and after surgery. RESULTS: In all patients, the retrodental pannus had significantly decreased or disappeared postoperatively. CONCLUSIONS: Pannus reduction occurred even in patients whose disease was active or progressing, supporting the hypothesis that the pannus is more a reactive fibrous tissue resulting from instability rather than a direct consequence of the inflammatory process itself.

Adult↗
PubMed1997

Fibre type characteristics of the lumbar paraspinal muscles in normal healthy subjects and in patients with low back pain.

A knowledge of the alteration in the fibre type profile of paraspinal muscle associated with low back pain is essential for the design of successful rehabilitation programmes. In attempting to compare the muscles of patients with low back pain with those of controls, few previous studies have considered factors such as gender, age, and size of the subjects, each of which can potentially confound interpretation of the results. We obtained samples of lumbar paraspinal muscle during spinal surgery from 21 patients with low back pain and, using the percutaneous biopsy technique, from 21 control volunteers matched for gender, age, and body mass. The samples were subject to routine histochemical analysis to determine characteristics of muscle fibre type. Compared with controls, the muscle of the patients had a significantly higher proportion of type-IIB (fast-twitch glycolytic) fibres than type-I (slow oxidative) fibres. The mean size of a given fibre type did not differ between the patients and the controls. Consequently, the relative area of the muscle occupied by type-IIB fibres was higher and that by type-I fibres was lower in the patients. The patients had a greater number of muscle samples with more than 1% type-IIC fibres, and abnormalities that could be described as pathological were more marked in the patients than in the controls. In conclusion, the paraspinal muscles of patients who have low back pain display a more glycolytic (faster) profile; this can be expected to render them less resistant to fatigue.

Adenosine Triphosphatases↗