Biomedical subjects

A Prescher

Publications and source records attributed to A Prescher.

95 records · Page 6Linked to original sources

PubMedDate not supplied

[Disruption of the arteria nutricia tibiae by reamed and unreamed intramedullary nailing. Study of the vascular architecture of the human tibial intramedullary cavity].

AIM: By reason of the pseudarthrotic healing of fractures due to vascular complications after reamed and unreamed intramedullary nailing, the intraosseous course and branching of the tibial nutrient artery and its impairment by nailing procedures needs an actual analysis. METHOD: The nutrient vessel of 24 tibiae taken from fresh corpses were prepared by injection of Technovit and lead oxide. After this procedure the medullary cavities of 12 bones were opened by a frontal cut. These specimens were subjected to routine maceration. The other 12 tibiae were naed with the unreamed (6) and the reamed nailing (6) techniques. X-rays were also taken routinely. RESULTS: After penetration of the tibial compact bone the main trunk of the nutrient vessel runs through a perforated osseous tunnel (pars tecta arteriae nutriciae tibiae). At its end the vessel divides into a descending branch (obligate) and two ascending branches (facultative). The descending branch lies near to the centromedial region of the medullary cavity which is termed as the pars liberal arteriae nutriciae tibiae. All branches pass through supporting horizontal osseous lamellas. Due to this topography the reamed nailing technique destroyed the nutrient vessel completely in all specimens. In contrast to this observation the unreamed nailing destroyed the vessel completely only in 1 (16.7%) and partially in 3 (50%) bones; 2 (33.3%) specimens exhibited no destruction of the vessel. CONCLUSION: The unreamed as well as the reamed nailing technique can destroy the intramedullary course of the tibial nutrient artery. Fractures as well as displacement osteotomies or corticotomies are able to diminish the medullary blood supply seriously, if they are localised within the area of the tactic an of the tibial nutrient artery.

Aged↗

PubMedDate not supplied

[Effect of femoral intramedullary irrigation on periprosthetic cement distribution: jet lavage versus syringe lavage].

INTRODUCTION: The purpose of this experimental study was to determine quantitatively the cement penetration into periprosthetic femoral bone by Icomparing the use of jet-lavage with the conventional syringe irrigation. METHODS: 10 pairs of fresh-frozen human cadaver femora were used for cemented stem implantation, The left femora were irrigated with a syringe device, the right femora with a jet-lavage system. After implantation, all femora were cut into 5-mm slices from proximal to distal with a diamond saw. The scanned slices were analysed using an image processing system which provided a discrimination between implant, cement, and bone as well as an exact determination of the cement area. RESULTS: In all 10 femora, a recognizable improvement of the cement penetration into the periprosthetic bone was demonstrated using the jet-lavage. In the proximal part, the mean cement penetration was 8.6% higher in the jet-lavage group than in the syringe device group. An equivalent tendency towards the jet-lavage pretreated femora was seen in the middle part with 8.7% on average mean and in the distal part with 6.4% on average. Also, when subdividing the periprosthetic area into 4 quadrants, a significant improvement of the cement penetration was found with the exception of the ventro-medial region. CONCLUSION: Cement distribution and penetration is improved using the jet-lavage technique for cleaning the medullary canal of the femur. Therefore, the jet-lavage should be used as a standard procedure in clinical cementing techniques.

Arthroplasty, Replacement, Hip↗

PubMedDate not supplied

[Accuracy of fluoroscopically navigated drilling procedures at the hip].

AIM: Many orthopaedic procedures require an accurate drilling in bone. The outcome is frequently dependent on the geometric accuracy of this surgical step. The precision of such a procedure can be improved with the help of fluoroscopic navigation. Reliability, accuracy and benefit of this new method for the patient, as well as for the surgical staff, need to be analysed. METHOD: In a standardised in vitro trial, the drilling of a 5 mm spherical lesion implanted in an artificial femoral head was performed using a navigated drill-guide and a navigated drill. In groups A and B, the distance of the tip of the drill to the center of the lesion was analysed in a 3D CT-generated model and in macroscopic cross section. Additionally, in group B the actual direction of the drill canal was measured. RESULTS: The mean distance in group A was measured to be 1 mm, with all results ranging between 0 and 2.5 mm. In group B the planned direction of the canal was reproduced with a deviation of 0 degrees to 7 degrees, the target only being missed by a mean distance of 2.5 mm and a maximum of 3.5 mm. Compared to the macroscopic and 3D-CT findings, the correlation of the data calculated by the navigation system was accurate up to a difference of 4 degrees or 2 mm. CONCLUSION: The fluoroscopically assisted freehand navigation used during the drilling of bone led to a high accuracy of three-dimensional tip placement while reducing radiation exposure to a minimum. It represents a promising and efficient application for a variety of procedures in orthopaedic surgery.

Artifacts↗

PubMedDate not supplied

[Computer-assisted retrograde drilling of osteochondritic lesions of the talus with the help of fluoroscopic navigation].

AIM: Due to the narrow access to the talar dome and the proximity of osteochondritic lesions to the joint surface, the therapeutic retrograde drilling often requires multiple attempts and repeated intraoperative X-ray-control. The advantages of a fluoroscopy-based computer-assisted navigation system regarding efficient planning and easy performance of the ideal drill path are evaluated in respect to accuracy and radiation exposure, as well as to time requirements. METHOD: A 5 mm spherical target was subcortically implanted in the medial aspect of the talar dome of 16 human cadaver specimens. Free-hand drilling was performed using the FluoroNav TM system in one group and conventional repetitive C-arm control in the other. The computed evaluation of the operative results was realized in a CT-generated 3D-model with the help of the DISOS planning and calculation program. The distance of the tip of the drill to the center of the lesion was measured, as well as X-ray exposure and total operating time. RESULTS: The CAS procedure missed the lesion only once. The mean deviation of the computer-guided drill path was measured to be 2 mm, whereas the conventional method led to a mean distance of 5 mm from the target. Conventional drilling failed to reach the target in 5 cases, violating the articular cartilage twice. Navigation reduced the traditionally required multiple attempts of the intervention to just one drill canal and reduced radiation time to 25 %. Despite the increased technical preparation required, the navigated procedure only exceeded the conventional operating time by 2 minutes. CONCLUSION: Thanks to the significantly increased accuracy, fluoroscopic navigation offers a high degree of safety and efficacy for this minimally invasive procedure. The operation can easily be performed successfully causing only minimal collateral damage to the bone, preserving the joint surface. The inherent risks of the retrograde drilling of osteochondritic lesions are lower with navigation, while the radiation exposure of the patient and the staff is significantly reduced.

Cadaver↗

PubMedDate not supplied

[Minimally-invasive computer-assisted fluoroscopic navigation for kyphoplasty].

AIM: The transpedicular placement of a hollow needle into vertebral bodies for kyphoplasty requires utmost accuracy and thereby permanent multiplanar X-ray control. Facing the increasing number of vertebral compression fractures, the aim of this work was the implementation of computer-assistance to optimise the issue. Prior to clinical implementation, experimental trials were undertaken to analyse the quality-improving options of the technique. METHOD: The virtual image of the planning and the puncture were correlated with the postoperative X-ray image of the needle. The real canal in the bone was then correlated with the preoperative planning in a CT-based 3D model and differences were calculated. As a measure of accuracy the deviation of the needle from the ideal intruding vector and the distance between its top and the centre of a predefined target were scrutinised and related to the indications of the navigation system. Operating time, radiation exposure and general applicability were additionally assessed. All data were compared with those of a conventional control group. RESULTS: Planning and navigation could be executed with high accuracy. With an exactly transpedicular approach, neural structures were safely circumnavigated without once missing the target. In the control group the distance fault was up to 9 mm. The navigated drilling differed from the ideal trajectory by 1 degrees to max. 4 degrees. Conventional C-arm control led to a divergence of 4 degrees to 8 degrees . Radiation exposure could be reduced through computer assistance by 76 % to a fourth of the conventionally resulting amount and the pure operating time thereby decreased by 40 %. The inconvenient course of repeated positioning of the C-arm was overcome. CONCLUSION: In challenging cases of deteriorated anatomy and difficult radiomorphologic orientation, especially of the lower thoracic spine, the CAOS-procedure succeeds in finding the optimal pedicular approach to the vertebral body, helps to avoid collateral damage and minimises the overall risk of the procedure. High accuracy and reduced radiation exposure justify the clinical use of fluoroscopic navigation for transpedicular instrumentation.

Decompression, Surgical↗