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Biomedical subjects

D Wolter

Publications and source records attributed to D Wolter.

At least 19 recordsLinked to original sources
PubMed1992

[The arterial blood supply of the tibial and practical consequences].

In the periosteum of the human tibia, the arterial blood supply shows a general sectorial angioarchitecture. There are 4 segments: proximal and distal 1/5, proximal and distal diaphysis. The proximal 1/5 of the tibial periosteum is supplied with blood by the aa. recurrentes tibiales anterior et posterior and the aa. inferiores medialis et lateralis genus. At the proximal diaphysis (next 3/10 of the tibia) periosteal branches arise from the a. tibialis anterior and the a. tibialis posterior. The distal diaphysis (following 3/10 below the middle of the tibia) is nourished exclusively by semicircular rami periostales of the a. tibialis anterior, which move around the bone from both sides and join with each other at the facies medialis. It is the only sector, which is supplied by a single main artery. Concerning the periosteal blood supply of the distal 1/5 of the tibia 2 different types are found. In 2/3 of the cases the lateral side is nourished by a great vessel of the a. fibularis, which is supported by branches arising from the a. tibialis anterior. In 1/3 of the cases this vessel of the a. fibularis is absent and rami periostales of the a. tibialis anterior nourish the lateral aspect of the distal tibia alone. The dorsal region is supplied in all cases by rami of the a. fibularis and a. tibialis posterior. On the medial side the periosteal nourishment is ensured only by anastomoses. Both the facies lateralis and the facies posterior are supplied by direct branches, which arise from the main arteries of the lower leg.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

[Fracture treatment in the area of the tibia].

From May 1990 to March 1992 17 open and 6 closed fractures of tibia and fibula with second- to third-degree soft tissue injuries were treated by external fixation using the Ilisarov technique. In 14 patients this external fixation was used as the primary treatment. In nine cases it was used secondarily, mainly in patients transferred after stabilization with other internal or external devices. The mean duration of fixation for diaphyseal tibial fractures was 127 days and for metaphyseal fractures, 107 days. After removal of the fixation device, a brace was temporarily fitted for full weight-bearing. Disadvantages observed include less comfort for the patient and longer operation time compared to other external fixation systems. On the other hand, this method allows full weight-bearing soon after the operation and involves minimal damage of soft tissue. Furthermore, injured soft tissue was well protected during healing.

Adolescent↗
PubMed1992

[Treatment of calcaneus and mid-foot fractures using closed reposition and fixation with the Ilisarov fixator].

Sixteen fractures of the calcaneus involving the subtalar joint were treated by closed reduction and external fixation using the Ilisarov apparatus. Except for four cases in which temporary arthrodesis of the subtalar or ankle joint was used, fixation was usually only used for the calcaneus. The operative technique is described precisely. Initial follow-up examinations (on average after 1 year) show advantages over conservative treatment, e.g. better anatomical reduction. In addition, early mobilization of the joint and early weight-bearing result in less pain from disuse osteoporosis. Furthermore, several case reports demonstrate the efficiency of this method in tarsal and metatarsal fracture-dislocations.

Adult↗
PubMed1992

[In vivo measurements of electric potentials of the Ilisarov external fixator].

Ilisarov's idea that electrical phenomena could contribute to the efficacy of the ring fixation apparatus prompted us to carry out this preliminary investigation. Patients with lower leg fractures and a four-ring fixation apparatus were selected; the electrical potentials were measured over non-fractured and fractured bones. Patients who could not be studied in the Faraday box were subjected to great disturbances, caused by mains voltage and a neighbouring transmitter; in these cases no objective results could be obtained. Only measurements in the Faraday box yielded reproducible results. The results demonstrate that there is generally a difference in electrical potential among the four rings in patients fitted with an Ilisarov apparatus. Furthermore, weight-bearing on the fixator-bone system causes changes in the electrical potential among the rings.

Bone and Bones↗
PubMed1992

[Initial modifications of the ring fixator apparatus].

To increase the practicability of Ilisarov's ring fixation apparatus, we introduced the following modifications: Clamping of the fixation wires using a quick collet with a force indicator, which enables reproducibly preuse and rapid clamping. Hardened screws to maintain the tension longer. Production of the olive wire from homogeneous implant steel by the cold-press method. Optimization of the cutting edge at the wire tip. Measurement of tension in the fixation wire. A distractor incorporating a clock and a device showing the distraction achieved so that doctor and patient can better supervise the distraction procedure. Simplifications of the wound dressing.

Biomechanical Phenomena↗
PubMed1992

[Indications and technique of combined dorso-ventral stabilization of the spine].

In delayed treatment of fracture dislocations or luxation of the cervical spine, combined dorsoventral operative treatment is necessary. After anatomical reduction from dorsal, stabilization is performed from ventral using autologous bone grafting and a plate. The injured intervertebral disk is removed to avoid protrusion. At the thoracolumbar spine this technique includes ventral bone grafting with a corticocancellous sandwich block and dorsal transpedicular fixation using an internal fixator system. This simplifies removal of the implant.

Adult↗
PubMed1991

[Development of a resorbable temporary skin replacement for large surface burn wounds].

Most of the temporary dressing used in the treatment of extensive burn wounds pose immunological permeability, or transparency problems. All available dressings must be removed, and removal is often painful and traumatic. The development of biodegradable wound dressings made of copolymers of lactic and caproic acid was part of a research program (BMFT/FRG). Four parameters determine the properties of the copolymers: Purity, mole ratio of monomers, molecular weight, and sequence. Films of these copolymers can be made transparent, permeable, and flexible. They are degraded by hydrolysis and the normal ways of metabolism.

Animals↗
PubMed1990

[The effect of an angle-stable plate-screw connection and various screw diameters on the stability of plate osteosynthesis. An FE model study].

In a finite element model of a human femur with an attached stainless steel six-hole plate exposed to a load equivalent to that set up by standing on one leg, pressures on the face of the screw holes, bending stresses in the screws, and axial bone stresses in the mid-plate transverse section were determined. The calculations were performed for minor thread diameters of 3 mm, 5 mm and 8 mm. Further calculations were done assuming a fixator-like rigid screw-plate connection. As a model of a fracture a medial bone defect was chosen. The results show a definitive influence of the screw diameter and the screw-plate connection on the load distribution in the system. Increasing screw diameter makes for lower bone stresses combined with increased bending stability, a larger part of the load being carried by the plate. The rigid screw-plate connection (plate fixator) causes less bone stresses, but high bending stresses are set up the points of screw-plate fixation. Maximal stresses for screw and bone are found at the end of the plate, caused by the large difference in the E-module between the steel plate and the bone. End-plate bone and screws are loaded in excess of their material limits when 3 mm core diameters are used, and sometimes when 5 mm core diameters are used, under the assumed conditions. When a medial bone defect reducing the bone cross-sectional area by 44% is present, the loads on the inner screws increase by a factor of 3 and the loads of the distant screws, by a factor of only 1.3. The maximal pressure in the bone cross section increases 4-fold.

Biomechanical Phenomena↗
PubMed1989

Glucocorticoids inhibit prostaglandin synthesis not only at the level of phospholipase A2 but also at the level of cyclo-oxygenase/PGE isomerase.

1. Prostanoid synthesis was induced in bone marrow-derived macrophages by addition of exogenous arachidonic acid to the cell cultures. When the cells were preincubated with dexamethasone (10(-7) and 10(-6) M) overnight, prostaglandin synthesis was inhibited by 66.5 +/- 2.8% and 56.7 +/- 2.9% (mean +/- s.d.; n = 3) respectively. 2. Endogenous membrane bound phospholipase A2 was measured with labelled phospholipids used as substrates. The enzyme activity with phosphatidylcholine and phosphatidylethanolamine as substrates was inhibited by 27.0 +/- 8.3% and 23.3 +/- 11.1% (n = 4) respectively, in dexamethasone-treated macrophages compared to control cells. Neither the distribution of radiolabelled arachidonic acid among the different phospholipid species nor the release of arachidonic acid from prelabelled cells were significantly impaired by pretreatment of the macrophages with dexamethasone (1 microM). 3. The enzyme activity of the cyclo-oxygenase/prostaglandin E (PGE) isomerase was measured in cell membranes from control cells and dexamethasone-treated cells. It was inhibited by 40.0 +/- 8.4% (n = 4) in dexamethasone-treated cells as compared to control cells. Thus, glucocorticoids inhibit not only phospholipase A2 in these cells, but predominantly inhibit arachidonic acid metabolism subsequent to its release from phospholipids.

Animals↗
PubMed1989

Progress in purification of virus-inactivated factor VIII concentrates. Three generations of solvent/detergent treated plasma derivatives.

A production process of a newly developed highly purified and virus-inactivated Factor (F) VIII-concentrate (Octa V.I. and Octavi) is presented. Taking advantage of a selective resin matrix and the solvent/detergent procedure for virus inactivation--known not to denaturate proteins--a product of a specific activity greater than or equal to 100 IU F VIII/mg could be developed in the final container without the use of an immuno-affinity adsorption step. The main steps of the procedure are: Pooled cryoprecipitate is extracted, the extract is cleared from fibrinogen at + 10 degrees C and virus-inactivated at + 28 degrees C after addition of tributyl-phosphate (TNBP) and detergent. Thereafter the extract is brought in contact to a F VIII-selective anion exchange resin using a chromatographic column. TnBP and the detergent are removed by an extensive washing process and the F VIII-activity is concentrated in a fraction, ready for filling, by means of a cascade of wahing- and elution-buffers. The product is free from coagulable protein and gamma-globulins. The F VIIIC: Ag/F VIII:C-ratio is about unity, suggesting the F VIII-molecule remained in its native state. The development of highly purified F VIII concentrate is based on two previous products of lesser purity (spec. activity of about 1 and 10 IU/mg). The evolution is shown by a comparison of detailed analytical data.

Chromatography, Ion Exchange↗
PubMed1989

[Possibilities and limits of therapy of injuries of the cervical vertebrae with halo fixation].

74 patients were treated with a Halo-thoracic brace in the Department of Traumatology of the AK St. Georg between 1980 and 1986. Of these, 61 had fractures of the cervical spine, nine had tumor-osteolysis, and four had inflammatory destructions of the vertebrae. In almost all cases of fractures of the upper cervical spine (C0-C2) bone healing occurred with applying the Halo fixation alone. In the middle and lower cervical spine, however, secondary operative measures were often necessary because of persistent instabilities, redislocations or neurologic disturbances. New experience in the palliative treatment of malignant osteolysis of the cervical spine shows, that restabilisation of the segments concerned can be achieved by the combined use the Halo apparatus, surgical resection of the involved vertebral bodies with bone grafting and radiotherapy. A new radiolucent Halo apparatus broadens diagnostic and therapeutic facilities.

Adult↗
PubMed1988

[Classification and prognosis of spinal injuries].

ABCD-0123-CLASSIFICATION: Taking into consideration the known classifications, a new scale of spiral injuries has been developed in which the three osteoligamentous columns (= three column spine) of the axial organ are designated by the letters A, B, and C. The letter D denotes the discoligamentous structures. This classification includes constriction of the spinal canal, whereby constriction of 1/3 is given the number 1, 2/3 the number 2, 3/3 the number 3, and no constriction 0. The prognosis of spinal injuries depends on many factors, especially the following: 1. Severeness of injury, 2. Time of operation, 3. Operation team, 4. Result of reconstruction and degree of stability, 5. Fusion distance, 6. Other diseases, and 7. Postoperative care. A good reconstruction of the spinal canal and good stability by short fusion in the injured part of the spine are very important for prognosis.

Humans↗