Biomedical subjects

Holger Schmitt

Publications and source records attributed to Holger Schmitt.

10 recordsLinked to original sources

PubMed2005

Stress fractures in adolescent competitive athletes with open physis.

There have been no studies devoted exclusively to stress fractures in competitive athletes with immature skeletal systems so far. The object of this case series was to describe special features of stress fractures in athletes with immature skeletal systems, with special reference to sport-specific strain, diagnosis and treatment results. The study population was made up of 19 children and adolescents with a total of 21 stress fractures. The average observation period was 4.83 years [standard deviation (SD) 2.69] and the average age at diagnosis, 14.04 years (SD 4.7). The lower extremity was affected in most of our cases. In adolescent athletes, endurance sports appear to lead preferentially to stress fractures in the region of the metatarsal bones, while sports requiring sudden stops at high speed appear to increase the risk of fractures in the region of the tibial diaphysis (P=0.0322). Most (20 of 21) of the fractures in this study were treated conservatively with refraining from athletic activity and reduction of stress/weight-bearing for an average of 6.73 weeks (SD 2.91). In five cases the extremity was in addition immobilized in a plaster cast for 5.32 weeks (SD 2.21). Complete healing was achieved in 14 cases. In seven cases, however, the treatment did not lead to a satisfactory outcome. Most of the patients whose symptoms persisted over a long period had fractures in the tibia and were engaged in sports requiring frequent sudden stops. Our data suggest that stress fractures in athletes, whose skeletal systems are still immature, lead to a clinical picture that does not always culminate in a good outcome of treatment. We therefore recommend a thorough and early diagnostic investigation (including MRI) and consistent treatment whenever a patient's history and clinical picture give any indication that a stress fracture might be present.

Adolescent↗

PubMed2005

Reconstruction of blood propagation in three-dimensional rotational X-ray angiography (3D-RA).

This paper presents a framework of non-interactive algorithms for the mapping of blood flow information to vessels in 3D-RA images. With the presented method, mapping of flow information to 3D-RA images is done automatically without user interaction. So far, radiologists had to perform this task by extensive image comparisons and did not obtain visualizations of the results. In our approach, flow information is reconstructed by forward projection of vessel pieces in a 3D-RA image to a two-dimensional projection series capturing the propagation of a short additional contrast agent bolus. For accurate 2D-3D image registration, an efficient patient motion compensation technique is introduced. As an exemplary flow-related quantity, bolus arrival times are reconstructed for the vessel pieces by matching of intensity-time curves. A plausibility check framework was developed which handles projection ambiguities and corrects for noisy flow reconstruction results. It is based on a linear programming approach to model the feeding structure of the vessel. The flow reconstruction method was applied to 12 cases of cerebral stenoses, AVMs and aneurysms, and it proved to be feasible in the clinical environment. The propagation of the injected contrast agent was reconstructed and visualized in three-dimensional images. The flow reconstruction method was able to visualize different types of useful information. In cases of stenosis of the middle cerebral artery (MCA), flow reconstruction can reveal impeded blood flow depending on the severeness of the stenosis. With cases of AVMs, flow reconstruction can clarify the feeding structure. The presented methods handle the problems imposed by clinical demands such as non-interactive algorithms, patient motion compensation, short reconstruction times, and technical requirements such as correction of noisy bolus arrival times and handling of overlapping vessel pieces. Problems occurred mainly in the reconstruction and segmentation of 3D-RA images in cases of complex AVMs. The concentration of injected contrast agent was often not sufficient to provide highly contrasted vessels in 3D-RA images. Another segmentation-related problem is known as 'kissing vessels' [19]. Kissing vessel artifacts introduce artificial vessel junctions and thereby distort the feeding structure of the vessel. This may finally cause implausible flow reconstruction results and inverse flow directions in vessel segments. We are currently planning to validate our reconstruction results using particle imaging velocimetry (PIV). PIV experiments with phantoms, for which the true flow parameters are known, will allow for the assessment of the accuracy of our contrast agent based method. In the context of computational fluid dynamics techniques, the potential of the presented flow reconstruction method is high. Flow reconstruction results based on the presented method could be used both as boundary conditions for simulations and as a reference for the validation of simulation results. Computational fluid dynamics provide useful information such as arterial wall shear stress and complex flow patterns in aneurysms.

Algorithms↗

PubMed2005

Workplace stress, lifestyle and social factors as correlates of back pain: a representative study of the German working population.

OBJECTIVES: To investigate the prevalence of back pain in the German working population and the relationship between back pain and workplace stresses, lifestyle and social factors. METHODS: The first National Health Survey of the Federal Republic of Germany was carried out between October 1997 and March 1999. It comprised a representative epidemiological cross-sectional study of the working population, with a total sample of 3,488 persons between the ages of 18 and 69 years. The participants took part in a medical examination and answered a self-rating questionnaire. The relationship between subjective back pain and workplace stresses and social and lifestyle factors was investigated with bivariate tests and multiple logistical regression analyses. RESULTS: The 7-day prevalence for back pain in the German working population was found to be 34%, and the 1-year prevalence was 60%. The odds ratios were significantly higher in women, persons of lower socioeconomic status, married and depressed persons and non-athletes. Carrying heavy loads or maintaining a single working posture were the most significant work-related correlates of back pain, for members of both the female and male working population, while environmental stress and psychological stress correlated significantly with back pain in men only. CONCLUSIONS: This study reports the first representative epidemiological prevalence data for back pain, and its correlates and potential risk factors, for the German working population. To reduce the negative impact of back pain the most promising behavioural and conditional prevention measures in the workplace would be to reduce carrying stress and to vary working posture. In addition, a more active, athletic lifestyle, plus the avoidance of being overweight, should provide an additional protective or preventive effect.

Adolescent↗

PubMed2005

Acute traumatic primary patellar dislocation: long-term results comparing conservative and surgical treatment.

OBJECTIVE: This report evaluates the subjective, clinical, and functional long-term results comparing surgical and conservative treatment in patients with a primary traumatic patellar dislocation. DESIGN AND SETTING: This retrospective clinical study focuses on patients with primary acute traumatic patellar dislocation. Patients with radiologic signs indicative of a predisposition for recurrent patellar instability were excluded from this study. PATIENTS: A total of 126 patients were examined a mean of 8.1 years after initial treatment of their primary patellar dislocation. INTERVENTIONS AND MAIN OUTCOME MEASUREMENTS: Patients were retrospectively divided into groups with conservative therapy (n = 63), diagnostic arthroscopy only (n = 20), immediate surgical reconstruction of the parapatellar ligament complex (n = 37), and refixation of osteochondral fragments (n = 6). Redislocation and resurgery rate, activity level, and subjective, clinical, and functional results were evaluated in these patients, and the outcomes in these groups were compared. RESULTS: In the long term, functional results (as expressed in the Lysholm score) were excellent or good in 85% of the patients, and good subjective results were reported by 71%, but follow-up revealed a recurrence rate of 26% in the total study population. The high activity level before the initial trauma could not be completely regained after treatment. There was no significant difference between the surgically and conservatively treated groups in the redislocation and reoperation rates, level of activity, or functional and subjective outcomes. CONCLUSIONS: Even with a focus on acute traumatic etiology and when factors predisposing to recurrent instability are largely excluded, the redislocation rate after treatment of acute patellar dislocation is still high, despite good clinical and subjective results. Conservative management seems to be the treatment of choice in patients with acute patellar dislocation, provided that the generally accepted indications for surgery, such as evidence of osteochondral fragments and major defects of the parapatellar ligament complex, are given due consideration.

Adolescent↗

PubMed2005

Influence of professional dance training on peak torque and proprioception at the ankle.

OBJECTIVE: To investigate the influence of professional dance training on the peak torque ratio of plantar flexion to dorsiflexion (PF/DF), angle replication ability, and balance in comparison to age-matched and gender-matched controls. The effects of injuries sustained before and during the study time period were also assessed. DESIGN: Prospective age-matched and gender-matched nonrandomized intervention study. SETTING: Premises of the Orthopedic University Hospital, Heidelberg, where measuring apparatus belonging to the hospital was used for the tests. PARTICIPANTS: One group of 42 dancers (31 female, 11 male) in professional training (State Academy) and 40 age-matched and gender-matched controls with no prior dance or specific sport training. MAIN OUTCOME MEASUREMENTS: Isokinetic tests for peak torque at 30 degrees /s and 120 degrees /s, a passive angle-replication test (Biodex system 3), and a test of 1-legged standing were each carried out on 2 measurement dates (M1, M2): at the beginning of a season of professional dance training (M1) and after 5 months of such training (M2). Symptoms and/or injuries sustained during this period were ascertained continuously by means of questionnaires and interviews. RESULTS: A significant increase in peak torque in PF was observed in both dancer groups and male controls between M1 and M2. A significant increase in PF/DF peak torque ratio at 30 degrees /s was observed in both male groups between M1 and M2. At M2, no significant differences in PF/DF peak torque ratio could be found between male dancers and controls, but at 30 degrees /s between the female groups. However, in both female groups, the PF/DF ratio was not found to increase significantly between M1 and M2. In the angle-replication and 1-legged standing test, no consistent improvement was observed between M1 and M2 in either dancers or controls. In the angle-replication test, there were no significant differences between dancers and controls at M2. In the 1-legged standing test, the dancers did significantly better than controls. A total of 7 ankle injuries were recorded, but no difference was found between injured and uninjured subjects in the proprioceptive tests either at M1, as the predicator, or at M2 as the residual. CONCLUSIONS: Dance training did not increase the peak torque ratio of PF/DF within 5 months, but a group difference was found between the women groups. Ballet training alone without concurrent additional coordinative training does not lead to improvements in ankle joint position sense or improved measures of balance within this period of observation.

Adolescent↗

PubMed2004

Radiographic changes in the lumbar spine in former elite athletes.

STUDY DESIGN: The authors conducted a retrospective cohort study. OBJECTIVE: The objective of this study was to clarify the occurrence of radiographic changes (vertebral osteophytes, heights of lumbar discs, concavity index) of the lumbar spine in former elite athletes of different track and field disciplines. SUMMARY OF BACKGROUND DATA: The influence of physical activity on occurrence of radiographic changes in the lumbar spine is not well known and seems to be contradictory. The loadings in the different track and field disciplines seem to play an important role in the development of radiographic changes. METHODS: One hundred fifty-nine former male elite track and field athletes were selected for a radiologic study. The heights of lumbar discs, the concavity index, the presence of anterior vertebral osteophytes, a radiographic evaluation according to Kellgren and Lawrence, and the FFbH-R score for the assessment of functional limitations in activities of daily living (ADLs) were determined. The influence of age, body mass index, current physical activity, and training history was also examined. RESULTS: In high jumpers and throwers, the absolute heights of lumbar discs increased from level T12/L1 to a maximum at L4/L5 and decreased again from level L4/L5-L5/S1. In endurance athletes and other jumpers, the absolute heights increased linearly from level T12/L1 to a maximum at L5/S1. The concavity index did not yield any significant differences between athlete categories. Shot putters, discus throwers, and high jumpers showed a significantly higher prevalence of osteophytes after adjustment for possible confounders. According to Kellgren and Lawrence, the highest prevalence of radiographic changes in the lumbar spine is seen in javelin throwers. Significant differences in the assessment of functional limitations in ADLs are not found between the disciplines. CONCLUSION: In throwing disciplines, the lumbar spine is more highly loaded than in jumpers and runners. Despite the observation of evident degenerative changes in some former athletes, there were only minor changes seen in ADLs. Even if body constitution is taken as a preselection factor, athletes in throwing disciplines as well as high jumpers have a higher risk of developing vertebral osteophytes of the lumbar spine.

Adult↗

PubMed2004

High prevalence of hip arthrosis in former elite javelin throwers and high jumpers: 41 athletes examined more than 10 years after retirement from competitive sports.

We studied the occurrence of hip arthrosis in 19 former elite javelin throwers and 22 former elite high jumpers 10 years or more after their retirement from competitive sports. Any restriction in the activities of daily living was assessed with an ADL-questionnaire. We compared the radiographic findings with male, age- and body mass index-matched controls (non-athletes). 22 of 38 hips in the javelin throwers (7 of 38 hips in the controls) and 15 of 44 hips in the high jumpers (6 of 44 hips in the controls) were classified as stage II or worse (Kellgren); hip arthrosis was commoner in both groups than in the controls. Despite considerable radiographic degenerative changes, the reduction of function in activities of daily living (FFbH score 96% in javelin throwers and 99% in high jumpers) was slight, as compared to a corresponding normal population. Javelin throwing and high jumping as competitive sports entail a high risk of subsequent hip arthrosis.

Activities of Daily Living↗

PubMed2003

Image stacking with entropy values in conventional angiography: initial experience.

The entropy method for stacking a series of angiographic images is presented and compared with the maximum opacity method, which is already established. The entropy method comprises calculation of the entropy of the time course for each image pixel. This accentuates image areas where a contrast agent bolus is passing. Quantitative analysis of the contrast-to-noise ratio and qualitative analysis of 11 cases were performed, the latter by eight independent viewers. Results indicate that the entropy images show more vascular detail in small peripheral vessels and increased contrast-to-noise ratio by up to a factor of 1.97 compared with maximum opacity images.

Adult↗

PubMed2003

Degenerative changes in the ankle in former elite high jumpers.

OBJECTIVE: The object of this study was to find what degenerative changes are present in the ankle (talotibiofibular) joints in former elite high jumpers at least 10 years after their retirement from competition, whether there are differences between takeoff and swinging leg, and whether correlations between any particular training history parameters, former injuries, and the degenerative changes can be recognized. DESIGN: A cross-sectional case control study with matched controls for radiological outcomes SETTING: The Orthopedic Department at the University of Heidelberg, Germany. PARTICIPANTS: The subjects were 40 male high jumpers (required personal best at least 2.18m), featured in the lists of top athletes kept by the German Athletics Association (DLV) from 1972 to 1986. All radiological findings were compared with X-rays of male age, and BMI-matched controls. MAIN OUTCOME MEASUREMENTS: All underwent clinical and radiological examinations. In addition to eliciting data on the training history with the aid of a questionnaire, we assessed symptoms affecting the ankle by means of the Freiburg Ankle Score and the Kitaoka Score and scored the radiological findings according to Bargon and Scranton and MacDermott. RESULTS: Differences between takeoff and swinging leg were small (Freiburg takeoff leg 93/swinging leg 95, Kitaoka takeoff 89/swinging leg 93 points on a 100 points scale) in both clinical scores, but statistically significant (p < 0.005). The more jumps were performed during the active phase, the worse the radiological scores (r(s) = 0.4, p = 0.01). Radiological differences between takeoff and swinging leg were not found. Comparison with controls revealed no radiological differences between athletes and age- and BMI-matched men (all p-values >0.40). It was found that one takeoff and one swinging leg ankle was affected by grade 2 arthritis (Bargon). Scranton grade 3 was found in four takeoff and in three swinging legs. No further correlations with training history data were found. Athletes who reported injuries in the past tended to have poorer radiological scores, although statistically not significant. None of the athletes had an instable ankle. CONCLUSIONS: The talotibiofibular joints in former high jumpers showed only slight signs of wear and tear with no clinically relevant side-related differences; severe arthrosis with narrowing of the joint space was rare. The risk of arthrosis connected with high-jumping seems not to be elevated.

Adult↗

PubMed2002

Sports activity of patients with idiopathic scoliosis at long-term follow-up.

OBJECTIVE: The aim of the study was to assess long-term the sports activities of operatively and nonoperatively treated patients with idiopathic scoliosis and compare these activities with those of controls. STUDY DESIGN: Cross-sectional case-control study, performed at The Orthopaedic University Hospital Heidelberg. PATIENTS AND METHODS: The study enrolled 59 patients (53 female, 6 male; mean age 43 years) with idiopathic scoliosis and a minimum follow-up of 5 years (mean 22 years) since treatment (28 nonoperative, 31 operative). Mean Cobb angle at the time of the study was 54 degrees. An age-adjusted control group (n = 33) with no history of spinal disorder was evaluated at the same time. All participants in the study (n = 92) completed a questionnaire assessing spinal function (Spine Score) and sporting activity (Sport Score). In addition, the scoliosis patients underwent radiographic evaluation of their spine. The groups were compared by analysis of variance. In order to assess the relationship between two variables, Spearman's correlation coefficient was calculated. RESULTS: Both groups of scoliosis patients attained a lower Sport Score than the controls (p < 0.015 and p < 0.006, respectively). There was no difference between the two scoliosis groups. Reduced spinal function correlated with reduced sports activity (p < 0.001). In both scoliosis groups, the subscales "back pain" and "physical activity" correlated with sporting activity (p < 0.03 and p < 0.02, respectively). In the surgically treated patients, Cobb angle correlated with reduced sports activity (p < 0.03). The extent of the spinal arthrodesis (number of segments) in surgically treated patients had no effect on their sports activity. CONCLUSIONS: Over the long term, patients with idiopathic scoliosis suffer impairment of their sports activities compared with age-matched controls. The main reasons for this are functional impairment and the frequency of back pain. Sports activity is not more restricted after extended spinal fusion than it is after nonoperative treatment.

Activities of Daily Living↗