Biomedical subjects

J Geerling

Publications and source records attributed to J Geerling.

At least 19 recordsLinked to original sources

PubMed2007

[Cost-benefit analysis of intraoperative 3D imaging].

BACKGROUND: With intraoperative 3D imaging, inevitable corrections may be done already during the operation, and a second procedure can be avoided. The purpose of this study was to perform a cost-benefit analysis during the first year of intraoperative 3D application in order to provide a cost transparency for the surgeon within the current DRG system. METHODS: On the basis of internal data and the literature, the annual operating costs of the ISO-C(3D) were calculated at 27,940 euros (purchase price, depreciation, maintenance, repair), the costs of an average revision as a secondary operation at 2,385 euros (costs avoided with the ISO-C(3D), Siremobil, Siemens, Erlangen, Germany), and the dynamic costs of an intraoperative 3D scan were averaged to 131.08 euros (draping, additional time, personnel). RESULTS: In the year 2003 intraoperative 3D scanning was done in 126 patients, and intraoperative revision was performed in 24 (19%) due to the additional intraoperative 3D information provided by the Siremobil. In 11 (8.7%) patients the implant position was corrected and in 13 (10.3%) patients the reduction was improved. Taking only fixed costs into consideration, 29,311.52 euros could be saved, and when fixed and dynamic costs are taken into account 12,795.44 euros could be saved. Since the parameters for each hospital are different, the following formula for an individual computation is suitable. For the calculation of the cost the following mathematical relationship results: (annual fixed costs) + (costs per scan x number of cases) - (revision costs x revision rate [p]) x number of cases [N]) = 0. DISCUSSION: Although the costs of an ISO-C(3D) are considerably high, an economic benefit can also accrue with frequent application and high rates of avoided revision. However, if the rate of avoided revision adds up to only 5%, a substantial deficit may result.

Cost-Benefit Analysis↗

PubMed2006

[Precision in orthopaedic computer navigation].

Navigation has become increasingly integrated into orthopaedic surgery, especially in the area of endoprosthetic procedures. Simplification of the instrumentation along with the use of imageless systems has increased the ease of use for the orthopaedic surgeon. Principle navigation systems enable an accuracy of corrections and alignments within intervals of 1 mm or 1 degrees . Consequently, potential intra- and interobserver failures during the registration procedure typically range within a few millimetres or degrees. Analysis of the actual algorithms used for the registration process of the lower extremity mechanical axis and the articular surfaces reveal valid and reproducible results. With the help of navigation, it is possible to achieve a higher degree of precision in total hip and knee implant placement, including a distinct reduction in variance as compared to conventional techniques. Similarly, application of navigation during a high tibial osteotomy or at the osteotomy of the distal radius also enables a more precise correction of the axis of the affected extremity, in addition to improved reproducibility. Despite these promising early results, large prospective clinical studies comparing conventional techniques versus computer assisted navigation are thus far only available for total knee arthroplasty. Whether navigated prosthesis placement can truly extend the longevity of an implant will require continued observation in the years to come. In addition, further prospective studies are required to determine the benefit of navigation in other orthopaedic procedures.

Orthopedics↗

PubMed2006

Navigated percutaneous pelvic sacroiliac screw fixation: experimental comparison of accuracy between fluoroscopy and Iso-C3D navigation.

Percutaneous sacroiliac screw fixation is technically demanding and can result in complications mainly related to imaging problems. Furthermore, the conventional technique performed using fluoroscopic control is associated with a long radiation exposure. The purpose of this study was to evaluate the accuracy of two navigation technologies used in traumatology; fluoroscopy and Iso-C3D navigation. A total of 40 screws were placed (20 with Iso-C3D, 20 with 2D fluoroscopy) at levels S1 and S2. With both technologies, all S1 screws could be placed correctly, but four (10%) incorrect placements were seen at S2 with fluoroscopy navigation. With all Iso-C3D navigated drillings, no perforation was seen. Iso-C3D navigation therefore proved superior to 2D fluoroscopy navigation for sacroiliac screw fixation in an experimental set-up designed to assess accuracy.

Bone Screws↗

PubMed2006

Preliminary clinical experience using a newly developed minimal-invasive reference base in computer assisted foot surgery.

In recent years, many new tools and techniques have been developed in computer assisted orthopaedic surgery primarily with an industry led effort in software innovation and development. Only a few research and clinical projects have focused on intraoperative difficulties. A common operative challenge in computer assisted orthopaedic surgery is the positioning of the reference base. Rigid fixation of a dynamic reference base is essential in navigated surgery of the extremities. The aim of this study was to develop a minimal-invasive screw which could be placed effectively and efficiently with rotational stability during computer assisted orthopaedic surgery. The minimal-invasive screw was initially evaluated in an artificial bone experiment. After successful results with the artificial bone experiment, it underwent testing in seven human cadaver thighs with ISO-C3D navigated drilling. Finally the screw was transferred into a clinical application during five foot surgeries. In 10 ISO-C3D navigated drillings, the lesions were targeted 100% of the drillings. A screw dislocation was not observed. In comparison to conventional one or two pin fixation systems, the newly designed small screw did not have any observed side effects such as artifacts. In addition, the screw generated less heterodyning than a conventional fixation system. The small screw design is an advantage in theatre. We believe the minimally-invasive screw allows the surgeon to use a tool that helps avoid common pitfalls from conventional fixation systems, and it may improve efficiency.

Bone Screws↗

PubMed2005

[Intraoperative three-dimensional imaging with an isocentric mobile C-arm at the wrist].

In addition to conventional radiological C-arm image amplifiers used for intraoperative imaging, now a new mobile C-arm image amplifier with an option for three dimensional imaging (Iso-C 3D) is available to visualize reduction of fractures and position of implants. In a wrist-model three titanium pins were placed and three holes of different length were drilled. Distances between the pins and the depths of the drilled holes were calculated in conventional computer tomographic scans and Iso-C 3D scans in perpendicular, 30 degree and 90 degree position of the gantry and compared to actual distances and depths. There were no significant differences between the actual measured distances and those measured by CT scans and Iso-C 3D scans. Furthermore, gantry position had no significant effect upon the results. Iso-C 3D scans are as reliable as conventional CT scans for intraoperative controlling of implant positioning.

Analysis of Variance↗

PubMed2004

[Computer-assisted surgery for pelvic injuries].

For pelvic fractures, pre- and postoperative imaging includes spiral computed tomography, providing high resolution and accuracy. In conventional pelvic operations, these image data cannot be used directly. Intraoperative imaging is limited with fluoroscopy and visualization by the approaches. One solution in terms of precision and reduction of radiation exposure could be computer-assisted surgery (CAS). This method can be divided into navigation, which requires active registration, CT based navigation and registration-free fluoroscopy-based or Iso-C-3D-based navigation. Applications for CAS in the pelvis include sacroiliac screw osteosynthesis in pelvic ring fractures, navigated periacetabular screw fixation, and correction operations for malhealed pelvic ring fractures. Nowadays, CAS is still costly and frequently requires additional staff. However, it helps to reduce complications caused by implant placement. With the introduction of new health care requirements in Germany, this may be an economic argument as well. Current developments focusing on accurate navigated reduction will provide new indications for CAS, further decrease complication rates, and help to reduce the invasiveness of pelvis operations.

Acetabulum↗

PubMed2004

[Restoration of the ability to walk through bilateral triple arthrodesis in marked spastic pes equinovarus].

A tendon transfer is the method of choice in easily reducible pes equinovarus. However, in long-time persisting deformities with spasms, a plantigrade position can not be maintained with these procedures. Therefore, we perform an additional bilateral triple arthrodesis in a patients with such bilateral deformities. A 55-year-old woman developed, within the scope of several surgical procedures on the cervical spine, marked bilateral pes equinovarus and flexion contractures of the knees. The patient's ambulation was limited to a wheelchair for 3 years. Then, in an interval of 1 year, we performed an unilateral soft tissue release, z-tenotomy of the Achilles tendon, triple arthrodesis with correction of the deformity, and posterior tibial tenden transfer. At follow-up 5 years after the second procedure, the 61-year-old patient was able to walk alone with two walking sticks. In the case described, the correction of a marked pes equinovarus with spasms, which was achieved by an extensive soft tissue release, could be stabilized through a triple arthrodesis in such way that the plantigrade position of the foot could be controlled through a posterior tibial tendon transfer.

Arthrodesis↗

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↗

PubMed2002

[Pediatric prehospital trauma care. A retrospective comparison of air and ground transportation].

OBJECTIVE: In contrast to prehospital care of adult trauma victims, prehospital care providers have only limited clinical experience of pediatric trauma cases as these are relatively infrequent. Literature reports on prehospital pediatric trauma care given by paramedics are frequently found in the literature, but there are few publications analyzing the quality of prehospital trauma care provided by emergency physicians in the care of injured children. It was the goal of this study to analyze the prehospital care of the pediatric trauma victims transported to a trauma center by physician-staffed ambulances and helicopters. METHODS: The study took the form of a retrospective 5-year review of pediatric trauma patients admitted to a trauma center. The inclusion criteria were age younger than 13 years and a NACA score higher than 3. In all, 104 patients were included, and these were divided into two groups, those transported to hospital by helicopter (RTH, n=87) and those taken to hospital by road ambulance (NEF, n=17). RESULTS: With a mean NACA score of 4.6 and a mean ISS of 15, no significant differences were found between the two groups in either severity of injury or length of hospital stay. The mortality of the total patient population was 15.4%, with no evidence of preventable deaths in patients who were admitted to the trauma center with vital signs. Analysis of prehospital therapy showed no differences in the volume of intravenous fluids administered (RTH 636 ml vs NEF 476 ml) or in the proportion of children with a GCS<9 in whom endotracheal intubation was implemented (RTH 39/44 vs NEF 7/7). Placement of more than one i.v. line and endotracheal intubation were associated with longer times at the scene of the accident before patients were taken to hospital (>one i.v. corresponded to 9 min longer, and endotracheal intubation, to 10 min longer). CONCLUSIONS: Prehospital pediatric trauma care delivered by physician-staffed ambulances or rescue helicopters is associated with a high rate of i.v. line placement (92%) and high intubation rates (90%) in patients with an altered level of consciousness (GCS<9). The prehospital care provided by helicopter or ground ambulance personnel was not different and was not associated with longer stays in the intensive care unit or longer overall stays in hospital. Scene times became longer with increasing number of i.v. line placements and with endotracheal intubation, but was not prolonged by a greater severity of injury as determined by the ISS. Preventable deaths were not observed in the patient population. In summary, owing to the the local infrastructure, pediatric trauma patients are more frequently transported to the trauma center by air (87 by air vs. 17 by road per 5-year time period). However, despite being less frequently involved in the case of pediatric trauma, the quality of care provided by road ambulance staff is similar to that in air ambulances.

Air Ambulances↗

PubMed2002

Computer-assisted fracture reduction of pelvic ring fractures: an in vitro study.

A newly developed software module for computer-assisted surgery based on a commercially available navigation system allows simultaneous, independent registration of two fragments and real-time navigation of both fragments while reduction occurs. To evaluate the accuracy three fracture models were used: geometric foam blocks, a pelvic ring injury with disruption of the symphysis and the sacroiliac joint, and a pelvic ring fracture with symphysis disruption and a transforaminal sacral fracture. One examiner did visual and navigated reduction and in all experiments the end point was defined as anatomic reduction. Residual displacement was measured with a magnetic motion tracking device. The results revealed a significantly increased residual displacement with navigated reduction compared with visual control. The differences were low, averaging 1 mm for residual translation and 0.7 degrees for the residual rotation, respectively. Residual displacement was small in both set-ups and may not be clinically relevant. Additional development of the software prototype with integration of surface registration may lead to improved handling and facilitated multifragment tracking. Use in the clinical setting should be possible within a short time.

Biomechanical Phenomena↗

PubMed2001

Primary subtalar arthrodesis of calcaneal fractures.

We evaluated retrospectively the long-term results of isolated calcaneal fractures treated with open reduction and internal fixation and a primary subtalar arthrodesis. From 1990 to 1997 258 patients were treated with a calcaneal fracture, for the current study six patients were included. Six different surgeons operated on the patients. The indication for the fusion was based on the comminution of the posterior facet according to the preoperative CT as well as the intraoperative evaluation of destruction of the cartilage. The restoration of length, axes and angles of the calcaneus was almost anatomical in all cases. Follow-up was done at a mean of 4.9 (2.5 - 7.5 years). Using the AOFAS score, the results were good or excellent in five patients. In one patient with a painful arthritis in the talonavicular joint and hyperesthesia of the sural nerve, the results were fair. All returned to their profession within 9 months and had no or only minor daily restrictions. The results are comparable with single surgeon series. We found open reconstruction of the calcaneus with primary fusion of the subtalar joint may be indicated in selected patients and, in these 6 patients led to good results.

Arthrodesis↗

PubMed1989