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Biomedical subjects

M Börner

Publications and source records attributed to M Börner.

At least 19 recordsLinked to original sources
PubMed2000

[VRATS--Virtual Reality Arthroscopy Training Simulator].

The subject of this paper is a highly interactive medical training system for arthroscopic surgery; this is based on computer graphics and virtual reality (VR) techniques and offers an alternative to conventional training methods. To provide the virtual environment, a realistic 3D representation of the knee joint is derived from 2D medical image data. The use of tracking techniques guarantees an intuitive handling of the surgical instruments. The system allows navigation via a virtual camera and interaction with the virtual anatomical structures. First approaches for the simulation of tissue deformation caused by collisions with the instruments are implemented. One important advantage over conventional training systems is the possibility of verifying the training progress. Work is in progress on the realization of tactile feedback with the aim of providing a higher degree of interactive realism.

Arthroscopy↗
PubMed2000

Planning system for computer assisted total knee replacement.

Total knee replacement (TKR) is a common orthopaedic surgical intervention and includes the removal of bone sections from the end of the femur and the top of the tibia for replacement by prosthetic components. Pain relief and functional improvement are predictable clinical results. But the accuracy of the alignment affects the surgical outcome and the longevity of the prosthesis. Hence, current total knee implantation systems attempt to align the knee joint in the mechanical axis for placement of the total knee components. These approaches use templates and plain radiographs for preoperative planning and alignment devices for bone cuts. To overcome the inherent inaccuracy of the presently used systems a computer-assisted planning system has been developed delivering the necessary control data for the intraoperative surgical robot system.

Arthroplasty, Replacement, Knee↗
PubMed1999

Computer-integrated revision total hip replacement surgery: concept and preliminary results.

This paper describes an ongoing project to develop a computer-integrated system to assist surgeons in revision total hip replacement (RTHR) surgery. In RTHR surgery, a failing orthopedic hip implant, typically cemented, is replaced with a new one by removing the old implant, removing the cement and fitting a new implant into an enlarged canal broached in the femur. RTHR surgery is a difficult procedure fraught with technical challenges and a high incidence of complications. The goals of the computer-based system are the significant reduction of cement removal labor and time, the elimination of cortical wall penetration and femur fracture, the improved positioning and fit of the new implant resulting from precise, high-quality canal milling and the reduction of bone sacrificed to fit the new implant. Our starting points are the ROBODOC system for primary hip replacement surgery and the manual RTHR surgical protocol. We first discuss the main difficulties of computer-integrated RTHR surgery and identify key issues and possible solutions. We then describe possible system architectures and protocols for preoperative planning and intraoperative execution. We present a summary of methods and preliminary results in CT image metal artifact removal, interactive cement cut-volume definition and cement machining, anatomy-based registration using fluoroscopic X-ray images and clinical trials using an extended RTHR version of ROBODOC. We conclude with a summary of lessons learned and a discussion of current and future work.

Algorithms↗
PubMed1999

[Computer-assisted surgery for hip endoprosthesis].

The use of computer-controlled robots for implanting cement-free prostheses requires exact preoperative planning on a three-dimensional graphics computer (ORTHODOC). For the first time ever, it has been possible to implement the three-dimensional plan using a computer-controlled robot working on patients. We assume that the considerably improved bone contact provided by the high-precision reaming process--an thus high primary stability--will lead to better incorporation in the bone. In experiments on dogs, in which cement-free hips had been implanted using computer-assisted robots, the animals showed much earlier and more uniform weight-bearing on the affected extremity than animals in a control group that had received conventional implants. In histological therms, the precise fit obtained by the ROBOCOC was accompanied by primary angiogenic healing patterns that all demonstrated labels during the first four weeks. The manually reamed comparators showed more pronounced fissure and defect healing, the healing patterns was irregular, and turnover activity was demonstrate.

Arthroplasty, Replacement, Hip↗
PubMed1998

Primary and revision total hip replacement using the Robodoc system.

The ROBODOC system was designed to address potential human errors in performing cementless total hip replacement. The system consists of a preoperative planning computer workstation (called ORTHODOC) and a five-axis robotic arm with a high speed milling device as an end effector. The combined experience of the United States Food and Drug Administration multicenter trial and the German postmarket use of the system are reported. The United States study is controlled and randomized with 136 hip replacements performed at three centers (65 ROBODOC and 62 control). Followup was 1 year on 127 hip replacements and 2 years on 93 hip replacements. No differences were found in the Harris hip scores or the Short Form Health Survey outcomes questionnaire. Length of stay also was not different, but the surgical time and blood loss were greater in the ROBODOC group. This was attributed to a learning curve at each center. Radiographs were evaluated by an independent bone radiologist and showed statistically better fit and positioning of the femoral component in the ROBODOC group. Complications were not different, except for three cases of intraoperative femoral fracture in the control group and none in the ROBODOC group. The German study reports on 858 patients, 42 with bilateral hip replacements and this includes 30 revision cases for a total of 900 hip replacements. The Harris hip score rose from 43.7 to 91.5. In these cases the surgical time declined quickly from 240 minutes for the first case to 90 minutes. No intraoperative femoral fractures occurred in 900 cases. Other complications were comparable with total hip replacements performed using conventional techniques. The ROBODOC system is thought to be safe and effective in producing radiographically superior implant fit and positioning while eliminating femoral fractures.

Adolescent↗
PubMed1997

[Computer-assisted robotics in hip endoprosthesis implantation].

The most important prerequisite for permanent fixation of an implant is primary stability. Osteointegration of the implant is a major goal in cementless total hip replacement (THR). This means direct contact between bone and implant leading to fixation of the implant in the bone without the interference of fibrous tissue. In addition to the design of the implant, the structure of the implant surface and the material of the implant, the specific operational technique plays a major role in permanent fixation. Only the conical fixation of femoral implants guarantees high primary stability in cementless THR. The type of fixation of the implant in the femoral cavity and the resulting load transfer from implant to bone has a decisive effect on the durability of the prostheses. In order to achieve optimal primary fixation of the implant, robot-assisted implantation of the cementless implant has been performed at the Berufsgenossenschaftliche Unfallklinik Frankfurt am Main since the summer of 1994. After preoperative planning at a three-dimensional graphic work station these data are transferred to the robot, which transforms the preoperative planning by milling the femoral cavity with the highest precision. So far this type of surgery has been performed on 300 patients. The encouraging postoperative results prompted us to install the second system of Robodoc at the Berufsgenossenschaftliche Unfallklinik Frankfurt.

Arthroplasty, Replacement, Hip↗
PubMed1997

[Mobilization of the tibial insertion of the anterior cruciate ligament: new therapeutic possibilities in surgery of the cruciate ligament].

In patients with a significant elongation of the ACL we propose a new therapeutic regimen. After mobilisation of the tibial insertion of the ACL we pull the bone block with the attached ACL distally. Thus the ACL is easily tightened. In accordance with this method, we describe the treatment of a case of a strictly proximal rupture of the ACL: the tibial insertion is mobilised, the bone block with the attached ACL removed from the joint. Ex vivo sutures are placed into the ACL, the ligament is pulled back into the joint, and the shortening of the ligament caused by the sutures is compensated by slight proximal dislocation of the bone block.

Anterior Cruciate Ligament↗
PubMed1997

[Computer-guided robot-assisted hip endoprosthesis].

Computer-guided robot-assisted surgery in cementless total hip replacement requires exact preoperative planning at the 3D workstation Orthodoc. Only the Robodoc procedure allows the precise execution of the preoperative plan in surgery. Robot-assisted surgery has been undergoing clinical evaluation at the Berufsgenossenschaftliche Unfallklinik, Frankfurt, since November 1994. In all 465 patients, the preoperative plan was successfully carried out intraoperatively. The high precision in reaming, leading to a superb bone implant contact, guarantees absolute initial stability and is likely to promote primary healing between implant and bone. The common and often published incidence of varus or valgus malpositioning and any fractures or fissures could be avoided through the use of Robodoc. Although immediate full-weight bearing was strongly recommended to the patients, no implant subsidence was seen in the treatment follow-up X ray studies.

Adult↗
PubMed1993

[American football in Germany--aspects of trauma surgery].

While football injuries in the USA are well documented and thoroughly studied, informations on injuries caused by this spreading sport in Germany are not available. For this reason the Berufsgenossenschaftliche Unfallklinik in Frankfurt conducted a prospective study to register all injuries in major league football in southern Germany in 1991. In 49 games that were evaluated we found 281 minor injuries, mainly skin lesions and concussions of extremities. In addition 33 significant injuries were registered, amongst them 30% injuries of knee ligaments. The only severe injury was an abdominal hit causing a intrahepatic hematoma. The results of our study are comparable to the injury risks found in US college football as well as to those found in German statistics on soccer and hockey. Although no fatal injuries in our study were registered, this should not lead to neglecting the potential risks in football.

Adult↗
PubMed1992

[Monteggia injuries in athletes. Causes, classification, results].

Monteggia-fractures are serious combination injuries to the forearm. Sport injuries are being increasingly observed; the reason for this, besides the general expansion of mass sports, is the increasing burden of high-performance sports. Monteggia fractures can occur during a fall on an outstretched arm, for example in motor or bicycle sport injuries, but also when falling from gymnastic equipment. Generally, it is easy to diagnose the monteggia injury. Considerable secondary damage could occur from the frequent failure to notice the involved radiohumeral joint. It should be demanded that in case of an uluar fracture the adjoining joints should be x-rayed on two planes in order not to overlook the possibility of a chisel fracture. The different forms of this combination injury, its classification and the results of our own medical bulletins are presented.

Athletic Injuries↗
PubMed1992

[Arthrodesis of the upper ankle joint. Indications, technique, results].

From 1984 to 1990 a total of 119 arthrodesis of the upper ankle joint were performed at the Hospital of Accident Surgery of the Trade Association in Frankfurt am Main. The results of 98 patients after an arthrodesis of the upper ankle joint are documented by an x-ray control series and patient files, including the expertise on the medical status of pensioners plus a follow-up examination of 34 patients. The indications and the results are discussed on the basis of the various procedures. The results confirm the method of a compressions arthrodesis with an extension screw in case of a posttraumatic arthrosis of the upper ankle joint, while a fixateur externe should be used in case of chronical osteomyelitis, osteoporotic bones, extensive tissue swellings and after a pilon or talus fragment fracture.

Ankle Injuries↗
PubMed1990

[The treatment of proximal femoral fractures using the interlocking nail].

The good result hoped for with interlocking nailing of the proximal part of the femoral shaft is only possible when precise diagnosis is of the fracture form is made with reference to informative X-rays and a meticulous operative technique is observed. Therefore, positioning of the patient on an extension table, the repositioning of the bone, the choice of the insertion point for the nail, and careful drilling are of the utmost important. All follow-up examinations conducted in 42 patients, we found good or very good results in 32 cases, satisfactory results in 7, and poor results in 3.

Adolescent↗
PubMed1990

[Results of interlocking nailing of distal tibial fractures].

Between 1982 and 1989, 117 fractures of the distal part of the lower leg were surgically treated in the Trauma Clinic belonging to the employers' liability insurance company in Frankfurt/Main. A follow-up examination of 85 of these patients, based on X-ray series, clinical reports, and insurance files, shows the functional results. Because of the high proportion of good to excellent results (95.4%), we consider fracture of the distal tibia a good indication for interlocking nailing, even from the aspect of the borderline indication of fracture in the fifth sixth. In open fractures of the distal part of the lower leg we consider the change of method from primary stabilization with external fixation to secondary interlocking nailing an appropriate procedure. The methods presented for internal fixation of fractures of the distal tibia by interlocking nailing allow early partial and full weight-bearing with the stability needed for exercising.

Adult↗
PubMed1988

[Fracture of the scaphoid bone--surgical treatment, indications, method and results].

In fractures of the scaphoid bone, conservative treatment leads to an osseous consolidation in 95% of all cases. A primary surgical treatment seems justified in case of instability by torsion, tilting, or shifting of the fragments, associated fractures of the same arm, as well as de Quervain dislocation fracture. The different surgical possibilities are described and the complications are compiled in a special study. The question if a recent fracture of the scaphoid bone should be managed by conservative or surgical treatment ist not justified considering the rate of 14.5% of complications, i.e. formation of pseudarthroses, observed after surgery of recent fractures of the scaphoid bone.

Carpal Bones↗
PubMed1986

[Treatment of chronic osteomyelitis with gentamicin PMMA chains].

In the treatment of chronic osteomyelitis radical removal of sequestrated bone fragments is of essential importance. Any antibiotic therapy - whether systemically or locally applied - can only be a supplementary measure. By implantation of gentamicin-PMMA-chains into infected cavities high local concentrations of the antibiotic can be achieved which are far above the minimal bactericidal concentrations of most common pathogens. As result of the very low concentrations of gentamicin in the serum and urine there is no hazard of nephrotoxicity and ototoxicity. Chronic sequestrating osteosyntheses and infected non-unions are the most important indications for the application of gentamicin-PMMA-chains.

Chronic Disease↗