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Biomedical subjects

C Krettek

Publications and source records attributed to C Krettek.

At least 91 records · Page 5Linked to original sources
PubMed2003

[Changes in the injury pattern of polytraumatized patients over the last 30 years].

This study aims at describing the changes in injury patterns in traffic accidents in Germany that have taken place over a 30 year period. The basis for the analysis is the in-depth investigations by the scientific research team at the Trauma Department of the Hanover Medical School. Real accidents were investigated based on an on site random selection process. The study includes 1,235 accidents from 1973 to 1978 and 5,608 accidents from the years 1994 to 1999. A reduction in number of fatalities, as well as a change in the injury pattern and the time of death in fatalities was observed. In the earlier years, 54.2% of the fatalities occurred during hospital treatment, whereas in the currant years 78.8% of the fatalities occurred directly at the accident scene and were mainly caused by much higher impact levels. In the earlier group, the polytraumatised patients suffered injuries of AIS 3+ to nearly all body regions (head 69.6%, thorax 69.2%, abdomen 51.9%, pelvis 33.1% and lower extremities 51.9%), whereas today only the head and chest are dominant injury locations for life-threatening trauma. Analysis of the collision configuration showed that nowadays the impact of cars against structures with a low profile such as poles and trees is responsible for the majority of severe, life-threatening injuries, whereas other injury patterns are of minor importance. For pedestrians and cyclists, the impact of the body on the windscreen of the car is the major reason for severe injuries. We conclude that the currently used safety methods have led to a change in the injury pattern of polytraumatised victims. Injuries with much higher energy levels can nowadays be survived, but when the safety limits are exceeded immediate death at the scene is more common.

Accidents, Traffic↗
PubMed2003

[Navigated reposition of transverse acetabulum fractures. A precision analysis].

Up to now navigated reduction control based on computed tomography (CT) image data could not be used commercially. With newly developed software, a transverse fracture of the acetabulum was reduced with navigation control in a laboratory test. The results were compared to visual and tactile control in a foam pelvis and specimen. Measurements were done with another magnet-based navigation system. The residual dislocation was measured with translation (mm) and rotation (degrees). Compared with visually controlled reduction, navigated reduction led to a residual dislocation of 0.7 mm and 0.9 degrees. Navigated reduction based on CT image data is also accurate for reduction of joint fractures under laboratory conditions. Further improvements of the software are planned for later in vivo use.

Acetabulum↗
PubMed2003

[Integration of modern technologies in therapy of sarcomas of the pelvis. Computer-assisted hemipelvectomy and implantation of a "custom-made" Bonit gentamycin coated partial pelvic prosthesis].

The resection of primary malignancies in the pelvis is technically demanding as organs and structures are to be preserved and reconstruction of the defect as well as the postoperative function and rehabilitation are dependent on an optimal prosthesis. We present two patients with a sarcoma of the pelvis where for the first time a structured concept of technology integration led to a press-fit implantation of a hemipelvic prosthesis. This concept includes the design and production of a "custom-made" prosthesis as a hemipelvic substitute and the coating of this prosthesis with Bonit, a second-generation calcium phosphate, and gentamycin in watery solution. The tumor resection was done with computer-assisted surgery based on computed tomographies (CT) of the pelvis model done by rapid prototyping rather than on the CT of the patients' pelvis. With this procedure the presurgically simulated resection could be executed precisely with complete resection of the tumors and an accuracy which allowed an exact implantation of the prosthesis. The course was uneventful with primary healing and no sign of an infection or loosening after 6 months.

Bone Neoplasms↗
PubMed2003

[Navigated Iso-C(3D)-based drilling of a osteochondral lesion of the talus].

Retrograde drilling of osteochondral lesions has obtained acceptable results in the initial stage. Intraoperatively not all lesions are accessible with the arthroscopic technique, despite being readily identifiable with modern imaging preoperatively. As an alternative, open surgical treatment is recommended to achieve good results. The use of computer-assisted navigated retrograde drilling of osteochondral lesions has been described with promising results as a new technique. Computed tomography (CT)- and fluoroscopy-based navigation systems in current use are limited in their flexibility. The drawbacks of fluoroscopy are lack of three-dimensional imaging intraoperatively. CT-based navigation still requires intraoperative cumbersome registration, extra preoperative planning, and imaging with further technical resources. In the current case report, we describe a patient with an osteochondral lesion of the posteromedial talus. In addition to the current method of arthroscopic evaluation and treatment, we also introduce an alternative technique of using Iso-C(3D)-based navigation-assisted retrograde drilling of the lesion. The advantages of this technique are an actual intraoperative three-dimensional imaging for the use of navigation without the need for anatomical registration and an immediate postoperative control of surgical treatment. The results of this case report demonstrate accurately navigated drilling with the described system. The accuracy was confirmed with immediate intraoperative Iso-C(3D) and postoperative CT scans. Our results indicate that the use of an Iso-C(3D) navigation system is a possible alternative to arthroscopic or open drilling for osteochondral lesions of the talus. To provide further evidence for the use of Iso-C (3D)-based drilling, current studies will start at our institution.

Adult↗
PubMed2003

[Navigated osteosynthesis of the proximal femur. An experimental study].

Screw position in femoral head has been considered the most important predictive factor for mechanical failure in pertrochanteric osteosynthesis, and correct positioning is assisted by fluoroscopic control. Although fluoroscopy leads to precise and reproducible results, it is associated with scattered radiation to the patient and surgical staff. Computer-assisted surgery (CAS) may be an alternative in means of achieving precise screw insertion with a low radiation dose. We designed a laboratory study in which artificial proximal femora were submitted to insertions of a dynamic hip screw (DHS) and an anti-rotational screw (ARS). Three set-ups were tested: (1) conventional implantation with two simultaneous C-arms using a guide wire; (2) drilling and implantation controlled by CAS solely with a 3.2-mm drill bit, then insertion of a guide wire and drilling for the dynamic hip screw; (3) after navigated drilling (3.2 mm) a fluoroscopic control was performed. Five variables were used comparing methods and surgeons: operation time, radiation time, tip-apex distance (TAD), and the insertion neck-shaft angles of DHS and ARS. Considering TAD as a precision parameter, CAS led to screw insertion as accurate as with fluoroscopic control, with a reduction of radiation time up to 93%.

Analysis of Variance↗
PubMed2003

[Diagnostics at the wrist].

Injuries of the wrist are difficult to diagnose because of the complex and narrow anatomic structures. Based on precise clinical examination, X-rays, CT, and MRI are valuable additional tools that can be used. If a fracture is suspected a CT scan is preferable. In the case of a suspected soft tissue or ligamentous injury and non-vital fragments or necrosis MRI is suitable. Other diagnostic tools are presently of minor importance for the wrist. Technical innovations allow better visualization and classification of lesions. However, exact knowledge of the tools is important.

Adult↗
PubMed2003

Trauma care in Germany.

Trauma Care in Germany fulfils all requirements to deal with injured young and mobile individuals as well as with an increasing number of injured elderly patient. Furthermore, it is prepared to cope with mass casualties of injured. As a public task the Trauma System in Germany is well organized and follows clear cut demands. To perform technical and medical therapy at highest available level as soon as possible, a ground system of physician staffed ambulances is supported by a network of physician-staffed HEMS all over Germany. Therefore, enormous efforts in financing, basic research and quality management have been undertaken during recent years to create such a sophisticated rescue system.

Accidents, Traffic↗
PubMed2003

LISS PLT: design, mechanical and biomechanical characteristics.

Following the development of the Less Invasive Sabilization System for Distal Femur a similar system for proximal tibia fractures (LISS PLT) was designed. Anatomical studies were carried out to define the shape of the plate and the position and orientation of the screws. Standard mechanical tests were performed to ensure that the LISS PLT fixation provides similar fatigue resistance to that of conventional plates. Finally, cadaver tibia pairs were used to compare the biomechanical performance of the new device to that of bilateral plating. An unstable intra-articular proximal tibia fracture model was used. The medial condyle of the tibias were submitted to loading cycles with increasing load levels and the vertical subsidence of the medial condyle during the loading cycles was monitored. Comparable stability against secondary loss of reduction was observed for the LISS PLT and the bilateral plating constructs.

Biomechanical Phenomena↗
PubMed2003

Comparison of human bone marrow stromal cells seeded on calcium-deficient hydroxyapatite, beta-tricalcium phosphate and demineralized bone matrix.

The aim of this study was to compare three resorbable biomaterials regarding seeding efficacy with human bone marrow stromal cells (BMSCs), cell penetration into the matrix, cell proliferation and osteogenic differentiation. Calcium-deficient hydroxyapatite (CDHA), beta-tricalcium phosphate (beta-TCP), and demineralized bone matrix (DBM) were seeded with human BMSCs and kept in human serum and osteogenic supplements for 3 weeks. Morphologic and biochemical evaluations were performed on day 1, 7, 14 and 21. The allograft DBM and CDHA exhibited both an excellent seeding efficacy while the performance of beta-TCP was lower when compared. The total protein content and the values for specific alkaline phosphatase (ALP) increased on all matrices and no significant difference was found for these two markers. BMSCs in monolayer had a significant increase of protein, but not of ALP. Osteocalcin (OC) values increased significantly higher for BMSC in cultures on DBM when compared to CDHA and beta-TCP. The OC levels decreased significantly in the BMSC monolayer culture. BMSCs were found inconsistently within the synthetic materials, whereas in DBM they were found more homogeneously distributed throughout the matrix. All three matrices promoted BMSC proliferation and differentiation to osteogenic cells. DBM allografts seem to be more favorable with respect to cell ingrowth tested by histology, and osteogenic differentiation ascertained by an increase of OC. CDHA with its high specific surface area showed more favorable properties than beta-TCP regarding reproducibility of the seeding efficacy.

Biocompatible Materials↗
PubMed2003

[Open reduction and internal fixation of unstable sacral fractures].

Sacral fractures are frequently misdiagnosed or overlooked, as the majority of the patients are suffering from polytrauma situations. Obvious clinical signs both of the fracture and the associated neurological complications are missing. A poor longterm outcome with pain and urogenital disorders is frequent. Based on clinical and biomechanical studies a new concept for internal fixation of transsacral pelvic instabilities combined with decompression of the central canal is applied. To approach the sacrum, a posterior longitudinal incision is carried out and can be modified according to the fracture pattern. Decompression and anatomic reduction is performed and the fracture stabilized with minimized small fragment implants which are solely fixed in the sacrum. 32 patients were treated according to this protocol between 1989 and 1996. Bony healing occurred in all but one case. A complete anatomical sacral reconstruction was achieved in 80 % of the cases, another 16 % had close to anatomic (< 5 mm) reconstruction. In eight cases a primary neurologic deficit was present, with five complete or partial recoveries directly postoperative. Complications occurred in seven patients with two secondary displacements.

Adolescent↗
PubMed2003

Failure of operative treatment in a child with osteoporosis-pseudoglioma syndrome.

A 6-year-old girl with osteoporosis-pseudoglioma syndrome had operative treatment of a distal femur fracture that failed. Osteoporosis-pseudoglioma syndrome is an autosomal recessive syndrome combining severe premature osteoporosis with a bilateral eye disorder leading to early onset of blindness. Beginning in early childhood, the patient sustained multiple fractures of the left distal femur that were treated nonoperatively. At the age of 5 years the patient had a fracture of the left distal femur with an 80 degrees angulation in the sagittal plane. The patient was treated with internal stabilization because of gross bowing of the femur at the fracture site. Intraoperatively, anatomic reduction was achieved by insertion of a flexible nail but not without some intraoperative problems. Because of the severe osteoporosis, iatrogenic penetration and fracture of the femoral cortex by the nail occurred intraoperatively in the subtrochanteric region. In addition, a hip spica cast was applied. The nail was removed 1 week later. After 6 weeks wearing the hip spica cast, the patient's fracture healed with some shortening but with correction of the angulation in the sagittal plane. Internal stabilization seems to be potentially troublesome in patients with severe forms of this syndrome and severe bony deformities.

Biomechanical Phenomena↗