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Biomedical subjects

R Hoffmann

Publications and source records attributed to R Hoffmann.

At least 289 records · Page 16Linked to original sources

[Biomechanical comparison of various emergency stabilization measures of the pelvic ring].

Massive bleeding with shock is still the most frequent reason for early death after complex pelvic trauma. For hemostasis, fracture stabilization in the pelvic ring is an important aspect. By use of the external fixator and introduction of emergency pelvic c-clamps, attempts were made to include pelvic ring stabilization on the early resuscitation algorithm. This biomechanical study compared a simple anterior external fixator (one supraacetabular pin on each side), the emergency pelvic c-clamp (Ganz) and the Browner modification of the clamp ("ACE clamp"). Two fresh-frozen human cadaver pelves were loaded in a one-leg stance model. The displacement and rotations on the site with the fracture were measured with a 3D measurement system. Fracture models included a Tile type B injury and two Tile type C instabilities (pure SI dislocation; transforaminal sacrum fracture). In type B injuries all methods withstood loading with 100% of the body weight (640/700 N). In C-type injuries with SI dislocation the external fixator showed no significant holding force, whereas the two c-clamps withstood loading of 112 N and 160 N. In the transforaminal fracture model no one method withstood a load of more than 40 N. The combination of the clamps with the external fixator increased the holding strength to 66 N and 103 N. Although a single-leg-stance model does not reflect the emergency situation, in which the patient is normally in a supine position, the data recorded are comparable to those observed in earlier investigations.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomechanical Phenomena↗

[Osteosynthesis of proximal femoral fractures with the modular interlocking system of unreamed AO femoral intramedullary nail. Initial clinical results].

The unreamed femoral nail system (UFN) features highly versatile proximal interlocking options for the treatment of a wide range of femoral fracture patterns and combinations. Besides standard interlocking modes for diaphyseal fractures, special interlocking options for subtrochanteric fractures and ipsilateral neck/shaft fractures are available. Two aiming arms can be attached to the insertion handle of the nail in a modular fashion. The standard aiming arm is designed for transverse static or dynamic locking. The special aiming arm permits spiral blade, 130 degrees, and miss-a-nail interlocking. From August 1992 to July 1994, in 10 out of 55 UFN implantations the special interlocking options were used. In 9 subtrochanteric fractures the spiral blade interlocking and in one ipsilateral neck/shaft fracture the miss-a-nail cancellous screw interlocking was applied. ASIF type A fractures with closed soft tissue damage prevailed. Fracture healing was uneventful and no implant complications or loss of reduction have been observed.

Adult↗

[The AO external clamp fixator. New techniques in external stabilization of tibial fractures].

A serious disadvantage of conventional external fixators is the opening of the medullary canal. This creates a direct communication between the canal and the exterior. The new pinless external fixator does not have this disadvantage. The clamps of the new fixator system do not penetrate cortical bone, they simply rest on the cortical surface. The clinical indications of this easily managed system are fractures of the tibial shaft in cases in which primary internal fixation is precluded either by precarious local or general conditions, or even by a lack of infrastructure. In such situations the pinless external fixator is an excellent device to achieve a good fracture stabilisation rapidly, while leaving open all subsequent alteration of treatment. In case of secondary change to an intramedullary nail the pinless fixator facilitates the procedure, because this fixator can be also used as an distractor during nailing. Furthermore this fixator can be combined with any intramedullary nail to increase the stability in case of very proximal or distal as well as highly instable shaft fractures. The clamps of the pinless external fixator set are used in combination with the standard AO fixator system.

Adult↗

[Instability of the shoulder joint in the athlete].

In all shoulder instabilities it is very important to classify the type of instability precisely in order to choose the right form of therapy and predict the results. The acronyms TUBS, which means traumatic instability, unidirectional, Bankart lesion, and good response to surgery, and AMBRI, which means atraumatic aetiology, multidirectional, and good for rehabilitation, represent the complete range of possible instabilities. We discuss the subtypes in the differentiation of various instabilities and the different causes and pathologies for instability, the clinical and radiological tests possible, and the different surgical treatment options, as well as the results in the literature. A modification of the Bankart procedure and the arthroscopic Caspari capsulorrhaphy procedure for traumatic instabilities are described. The capsular T-shift by Neer and Foster is explained as a surgical treatment for multidirectional instability.

Arthroscopes↗

[Principles for treatment of open fractures].

Fractures with soft-tissue injury are urgent surgical emergencies. Fracture care in the first few hours after the injury crucially determines the course of healing. In open fractures aggressive debridement of all necrotic tissues is mandatory as well as stable external or internal fracture fixation. Secondary wound closure must be performed liberally and prophylactic antibiotics should be administered. Closely observing such a stringent regimen, the rate of posttraumatic osteitis in open fractures can be reduced significantly.

Anti-Bacterial Agents↗

[Laparoscopic cholecystectomy: heat damage to the liver caused by hooked electrode and laser].

To control heat damage in the liver after cholecystectomy caused by electrosurgery or Laser, gallbladders were resected at autopsy partly by the Holmium:YAG-Laser and Nd:YAG-Laser and partly by electrosurgery. Heat damage was documented by histological examinations of the liver-bed of the gallbladder. Microscopical evaluation showed that electrocautery tends to produce deeper heat damage in the liver-tissue than the Holmium:YAG-Laser.

Burns↗

[A new procedure for determination of leg length and differences in leg length using sonography. I. Development and experimental studies].

The precise measurement of leg length and leg length discrepancies (LLD) plays an important role in the examination of lumbar spine and lower extremities. Those real LLD which may be posttraumatic or idiopathic, can sometimes hardly be differentiated from LLD caused by spinal scoliosis or malposition. Although there is no final agreement, to which extent a LLD becomes clinically significant, most authors state that clinical assessment of LLD by tape measure or lengthening of the short leg with blocks of known thickness is highly unreliable. Radiological methods are necessary for precise detection of LLD less than 10 mm. Since previously reported non-invasive, ultrasound-supported leg-length measurement methods proved to be complicated and unhandy, a new method was developed. To avoid radiation exposure accuracy and precision were tested on human cadavers and were compared to clinical assessments by tape measurement. A measurement device was constructed consisting of a wire rope meter and a length millimeter digital display. Measurements were taken with the examined person in supine position. The device was placed beyond their feet and the end of the rope was hinged with a metal brace to a convenient transducer in exact middle position. Thus the middle of the ultrasound monitor concords with the end of the rope. The medial knee joint and ventral hip joint were used as standardised sonographic landmarks. Ten not pre-selected mortants were measured in this manner and additionally clinical LLD was obtained with a tape measure (medial ankle to anterior superior iliac spine). Afterwards all distances were anatomically prepared and measured with a meter stick.(ABSTRACT TRUNCATED AT 250 WORDS)

Equipment Design↗

Surgery and environmental influence as risk-factors for the development of deep vein thrombosis in animal experiments.

The aim of this experimental study was to determine whether deep vein thrombosis (DVT) in animals occurs after osteosynthesis of the femur, and whether a postoperative drop in air pressure increases the frequency of DVT. Thus, osteosynthesis of the femur was performed in 10 New Zealand rabbits. Postoperatively a drop in air pressure of 300 hPA was induced. After 40 h in the pressure cabin ascending phlebography was performed (Group A). In a control-group of 10 other rabbits surgery was performed without postoperative drop in air pressure (Group B) while in a second control only the drop in air pressure was induced without surgery (Group C). The phlebographic studies showed DVT in 4 out of 10 rabbits in group A. In group B there was no demonstrable DVT while in group C one case of DVT was seen. The difference between group A and group B and C is statistically significant. In conclusion, a rapid drop in air pressure seems to have significant impact on the pathogenesis of DVT in rabbits after osteosynthesis of the femur.

Air Pressure↗

[Functional therapy of Achilles tendon rupture].

We are going to present two cases with functional treatment of Achilles tendon ruptures. We define a treatment as functional if the involved limb is either not immobilized at all or whenever the immobilization is incomplete and for a limited time only and when no operation is necessary. The functional treatment is presented as an alternative, and we are going to present the advantage and disadvantage.

Achilles Tendon↗

Comparative evaluation of bicycle and dobutamine stress echocardiography with perfusion scintigraphy and bicycle electrocardiogram for identification of coronary artery disease.

In 66 patients with suspected coronary artery disease (CAD), exercise electrocardiography (ECG), exercise echocardiography, dobutamine stress echocardiography (dosage, 5 to 40 micrograms/kg/min), single-photon emission computed tomography (SPECT) using methoxy-isobutyl-isonitrile (MIBI) and coronary angiography were performed prospectively to compare methods for detecting CAD. CAD was defined as 70% luminal area stenosis in at least 1 coronary artery at coronary angiography. Significant CAD was present in 50 patients. Compared with exercise ECG, exercise echocardiography, dobutamine stress echocardiography and MIBI-SPECT had a significantly higher sensitivity (52% vs 80, 79 and 89%; p < 0.01, p < 0.01 and p < 0.001, respectively). There were no significant differences in sensitivity between exercise echocardiography, dobutamine stress echocardiography and MIBI-SPECT. Specificity of MIBI-SPECT was lowest (71%), whereas exercise ECG, exercise and dobutamine echocardiography had higher specificities (93, 87 and 81%, respectively). Significance, however, was not achieved. Differences in overall accuracy between exercise echocardiography (82%), dobutamine stress echocardiography (80%) and MIBI-SPECT (85%) were not significant. Comparison with accuracy of exercise ECG (62%) was significant (p < 0.05, p < 0.05 and p < 0.01, respectively). In 1-vessel disease, exercise ECG had a lower sensitivity (45%) than exercise and dobutamine echocardiography and MIBI-SPECT (79, 78 and 84%; p < 0.02, p < 0.02 and p < 0.01, respectively). Regarding the 24 patients with false-negative exercise ECG results, 67% had positive exercise echocardiography findings, 71% positive dobutamine echocardiography results and 84% positive technetium-99m MIBI-SPECT results.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

[Rupture of an aneurysm of the common hepatic artery with pancreatic necrosis].

A male patient known to have hemophilia A was operated on twice (1990, 1991) in the Department of Surgery, University Hospital, Zurich, first because of severe intraabdominal hemorrhage from a liver artery aneurysm, and then because of a ruptured common hepatic artery aneurysm. The second surgical intervention revealed necrosis of the head and body of the pancreas. We consider that the pancreatic necrosis had resulted from the aneurysm, in view of the patient's history of silent pancreatitis and the uncomplicated postoperative course. Immediate reconstruction of the common hepatic artery aneurysm (in the presence of an occluded gastroduodenal artery) was performed with saphenous vein interposition. Because visceral aneurysms may be multiple, further aneurysms must be sought at the time of the first diagnosis. Elective surgery is the method of choice, because 40-80% of visceral aneurysms rupture spontaneously, with a high mortality rate. The mortality rate for elective surgery is now low.

Aneurysm, False↗

Restrictive dermopathy: a lethal congenital skin disorder.

Restrictive dermopathy is a recently described lethal congenital disorder of the skin with an autosomal recessive mode of inheritance. The rigidity of the skin impairs fetal movements in utero and causes arthrogryposis, as well as highly characteristic facial features and pulmonary hypoplasia. We report two cases of restrictive dermopathy in prematurely born infants, describe the typical pathological findings and discuss this disorder in the context of the fetal akinesia/hypokinesia deformation sequence.

Abnormalities, Multiple↗

Planimetry of orifice area in aortic stenosis using multiplane transesophageal echocardiography.

OBJECTIVES: The purpose of this study was to investigate whether the orifice area in aortic stenosis can be determined accurately and reliably by multiplane transesophageal echocardiography. BACKGROUND: Monoplane transesophageal echocardiography has been used for planimetry of aortic valve orifice areas; however, obtaining a precise short-axis view is sometimes impossible. METHODS: In 41 consecutive patients with known valvular calcific aortic stenosis (20 men, mean age 64 +/- 9 years), aortic valve orifice area was measured by planimetry using a multiplane transesophageal echocardiographic probe that allows full rotation of the cross-sectional plane. Results were compared with invasive measurements obtained by the Gorlin formula and areas determined noninvasively by transthoracic echocardiography using the continuity equation. RESULTS: Multiplane transducer technology enabled the rotation of the cross-sectional plane from an exactly aligned long-axis view of the stenosed valve to a precise short-axis view without moving the tip of the echocardiographic probe, thus achieving an orifice cross section at a level predetermined in the long-axis view. Planimetry was feasible in 38 patients (93%). In three patients with pinhole stenosis (area determined by the Gorlin formula < 0.4 cm2), the valve area could not be exactly delineated. Correlation between areas derived by transesophageal echocardiographic planimetry (0.56 +/- 0.31 cm2) and by the Gorlin formula (0.58 +/- 0.31 cm2) was excellent (r = 0.95; standard deviation of regression [SDR] = 0.054; Y = 0.92X + 0.085, where Y = Gorlin area and X = planimetry area). Correlation between Gorlin- and continuity equation-derived areas (0.65 +/- 0.46 cm2) was r = 0.79; for continuity equation- and transesophageal planimetry-derived areas it was r = 0.83. Severe aortic stenosis (valve area < or = 0.75 cm2) was predicted with high sensitivity (96%) and specificity (88%). CONCLUSIONS: Multiplane transesophageal echocardiography is a practical and accurate clinical tool for the assessment of the severity of aortic stenosis.

Aged↗

Increased frequency of CD8+ CD45R0+ memory T lymphocytes in acute hepatitis B virus infection.

CD8+ lymphocytes of the memory subset (= CD45R0+) encompass antigen-specific effector cells, which are believed to be decisive for virus elimination in several viral infections. To determine whether this can be extended to HBV infection naive and memory T cells were studied among CD(4+)- and CD(8+)-lymphocytes and used monoclonal antibodies in two-color flow cytometric analysis to quantitate functional T cell subsets in peripheral blood of patients with acute hepatitis B (n = 11), chronic hepatitis B (n = 24) and healthy individuals (n = 26). Compared to CD4+ populations of healthy individuals the number of total CD4+ lymphocytes in patients with both acute or chronic hepatitis was significantly reduced. In contrast CD8+ cells did not significantly change in either acute and chronic hepatitis. Analysis of naive and memory subsets demonstrated, however, a significant rise in CD45R0+ memory cells from 5 to 15% (70% of all CD8+ cells) in acute hepatitis. These changes within the CD8+ population were, however, restricted to the acute phase of hepatitis in that the frequency of CD8+CD45R0+ decreased within weeks post infection. Furthermore, patients with chronic hepatitis did exhibit normal values of CD8+ memory cells (30% of all CD8+ cells). These findings suggest that enrichment of CD8+CD45R0+ memory cells reflects an accumulation of functional effector cells, which may be specifically activated by viral antigens and determine the outcome of infection.

Acute Disease↗

The incidence of osteitis in open fractures: an analysis of 948 open fractures (a review of the Hannover experience).

Even though treatment protocols of open fractures have been improved in the past two decades, osteitis is still a major complication in these injuries. To investigate the primary factors responsible for posttraumatic osteitis, 19 cases of osteitis out of 297 open fractures (retrospective series from 1981 to 1983) and nine cases of osteitis out of 651 open fractures (prospective series from 1984 to 1989) were analyzed. The Hannover fracture scale was used for quantitative evaluation of the injury. A high prognostic index for bone infections was found for the amount of bone loss, the fracture type, the type of bacteriologic contamination, deep soft-tissue defects, compartment syndromes, vascular injuries, and soft-tissue infections.

Fractures, Open↗