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Biomedical subjects

C Dorow

Publications and source records attributed to C Dorow.

13 recordsLinked to original sources
PubMed2004

Viscoelastic response of the periodontal ligament: an experimental-numerical analysis.

A viscoelastic constitutive model for the periodontal ligament (PDL) capable of accounting for large strains, anisotropy, and inelastic time-dependent effects was developed. Anisotropy characteristics are determined by the composite nature of the tissue and, in particular, by the distribution of collagen fibres. Time-dependent viscous phenomena are due to microstructural modifications during loading, such as fluid fluxes moving through the solid matrix and the internal rearrangement of fibers and constitutive adaptation. The viscoelastic model presented here was implemented in a general purpose finite element code. In vitro experimental tests were carried out on the PDL specimens of adult pigs to obtain stress-relaxation and cyclic stress-strain curves. The comparison of experimental and numerical results revealed good correspondence and confirmed the capability of the formulation assumed to properly interpret the viscoelastic behavior of the PDL.

Animals↗
PubMed1998

[Joint empyema].

Bacterial joint infection is rare but may have an unfavourable functional aotcome. The different stages of purulent arthritis, depending on the pathophysiological developments, require different treatment measures. Clinical examination, analysis of joint tap and arthroscopy are crucial for diagnosis. Surgical management comprises: (1) open or arthroscopic débridement with intensive flush lavage; (2) postoperative drainage and flush lavage; (3) early and continuous active and passive motion. Recovery will be complete only if therapy is instituted as early as possible (within 3 days). Joint empyema must therefore be treated as a surgical emergency.

Adult↗
PubMed1998

[Traumatic peripheral vascular injuries].

2-4% of vascular injuries need operative reconstruction. In polytraumatized patients the rate is even 10%. Arterial vascular repair should precede venous reconstruction and orthopaedic stabilization due to limb threatening ischemia. Penetration or blunt vascular trauma result either in acute blood loss, ischemia or compartmental compression. Reperfusion syndrome leads to vital threat of patient. Clinical assessment, measurement of limb pressures using a Doppler device and use of duplex ultrasonography are reliable adjuncts in the rapid evaluation. Arteriography is rarely indicated and should be spared for patients with abnormal physical examination. Minimizing ischemia (6-8 h) is an important factor in maximizing limb salvage. Vascular repair include direct anastomosis or lateral suture repair mostly combined with primary shortening of the extremity. In most cases autogenous vein graft is required. Rethrombosis, arteriovenous fistula and pseudoaneurysms are possible complications. Stabilisation of the fracture has priority over vascular reconstruction. The initial steps to success are surgical debridement, adequate bony stabilization mostly by external fixation, revascularisation of vascular injury, immediate fascial decompression and early soft-tissue reconstruction. The best results are obtained when a multidisciplinary approach is used combining expertise in orthopedic surgery, vascular surgery and plastic surgery.

Arteries↗
PubMed1997

[Therapy of soft tissue injuries--biological strategies].

The traumatic soft tissue injury plays a central role in fracture healing. The knowledge of pathophysiological mechanisms has completely changed the management and therapy of injuries accompanied by soft tissue lesions. Treatment is aiming for prevention of the circle of hypoxia, microvascular perfusion disturbance, increased membrane permeability and potential infections. General therapeutic principles are decontamination, debridement, revascularisation and decompression. Modern methods of soft tissue treatment take these principles into consideration.

Debridement↗
PubMed1996

[Trauma in elderly patients].

The increasing proportion of old and very old people in the population has increased the task of treatment in the field of surgery and its main points. The decreasing function of and changes to the skeleton caused by osteoporosis have led to a number of fractures. The fracture near the hip joint is typical for this section of the population. 1180 patients from the Jena surgical clinic/casualty were analysed; the average age was over 75 years and the most common cause of accident was a fall. A quick operative treatment is recommended. In comparison with the risk factor of the ASA-classification 1.6% with factor I and 44.4% with factor IV died. Postoperative treatment is very important.

Accidental Falls↗
PubMed1995

[Principles of osteosynthesis of the hand].

In cases of joint fractures as well as in dislocated and open fractures of the hand special standards concerning operation methods have to be set. Treatment of soft tissue damage accompanying the fracture is in no other region of the body so important. Therefore the current efforts for development of an AO-classification for fractures of the hand taking into account the soft tissue damage are of major significance. Special features of miniosteosynthesis compared to conventional osteosynthesis are the subject of this study. The use of the miniplate especially in juxtaarticular fractures of the hand due to complex injuries or replantations can overcome the disadvantages of joint-bridging K-wires. Osteosyntheses of the hand are making high technical demands on surgeons and are not at all operations for beginners.

Bone Plates↗
PubMed1993

[Amputation injuries of the upper extremity--early complications after replantation and revascularization].

Within a time of ten years 144 patients with difficult injuries on their hands were operated. These were 95 replantations and 102 revascularizations. 26 patients had to be operated again because of arterial and venous thrombosis. 46% of our patients had early vascular complications already within 24 hours. The frequency of thrombosis was increasing with the accompanying soft tissue injury and therefore with the gravity of the trauma. Avulsion injuries had of course the worst prognosis. After diagnosis of vascular occlusion within the replanted finger there should be a quick surgical revision of the anastomosis. With the help of application of urokinase into the artery we could create the circulation without any new production of the anastomosis in two cases. With a subtile technique of the disposition of the anastomosis and two venous connections to one artery with the replanted fingers we could reduce the rate of thrombosis and improve the results.

Adult↗
PubMed1992

[Drug modification of post-traumatic edema of the extremities by the proteinase inhibitor aprotinin. An animal experiment study].

Posttraumatic edema remains a serious problem in traumatology. Unrecognized or improperly treated, edema poses a threat to the survival of any extremity, particularly the hand, where a number of intricate functional structures are at stake. This study, as well as other recent clinical and experimental work, show that aprotinin, a proteinase inhibitor, is valuable in the treatment of posttraumatic edema, provided it is given as early as possible and in an adequate dosage.

Animals↗
PubMed1991

[Results and late sequelae of colectomy].

Results after 55 colectomies are reported in the period from 1962-1986. The surgical intervention was indicated by ulcerative colitis in 19, Crohn's disease in 18 and familial polyposis of the colon in 18 cases. 37 total colectomies, 12 subtotal colectomies with ileorectal anastomosis and 6 colectomies with a remaining terminal closed stump of the rectum were performed. During the period of observation postoperative lethality decreased from 37% to 6%. Death was most frequently caused by thromboemboli and peritonitis. In 44% of the patients ill with familial polyposis malignant degeneration could be observed. 3 died by generalized metastases. Metabolism of protein, lipid and electrolyte showed no essential disturbances after colectomy. Intestinal assimilation was nearly standard. More difficult is social reintegration.

Adenomatous Polyposis Coli↗
PubMedDate not supplied

A transversally isotropic elasto-damage constitutive model for the periodontal ligament.

A numerical formulation of an elasto-damage constitutive model was developed and implemented in a finite element software to investigate the biomechanical response of the periodontal ligament (PDL). The mathematical framework accounts for the description of large strains, anisotropy and inelastic phenomena. The anisotropic mechanical response is caused by the spatial orientation of the sub-structures of the tissue, such as collagen fibres. Inelastic behaviour, induced by high level strains, is modelled by means of damage models. In vitro experimental testing on PDL samples from pigs was performed to obtain tensile stress-strain curves. A finite element analysis is presented in order to define a general numerical approach. A comparison of numerical and experimental data is provided in order to show the reliability and effectiveness of the formulation assumed.

Animals↗
PubMedDate not supplied

[Experimental model of tooth mobility in the human "in vivo"].

The aim of the present study was to investigate experimentally the mechanical properties of tooth deflection under external loading. These properties have a significant impact on tooth movement during orthodontic treatment. The stresses and strains caused by tooth movement influence bone remodelling, which is the basis of orthodontic treatment. The movement of a tooth as a direct reaction to the forces acting on it is termed "initial" movement. It is nonlinear and has a clearly time-dependent component. While the initial tooth movement represents the totality of the reaction mechanisms of all the tissues of the tooth unit, it is determined primarily by the mechanical properties of the periodontal ligament (PDL). The PDL is the softest tissue of the tooth unit and is therefore subject to the largest deformations when forces act on the crown of the tooth. The objective of orthodontic treatment is to achieve as precise and rapid tooth movement as possible, without provoking such undesired effects as bone and root resorption. To enable the implementation of an optimal orthodontic force system that meets these requirements, a thorough knowledge of the biomechanics of tooth movement is a must.

Biomechanical Phenomena↗