Biomedical subjects
Publications and source records attributed to M Tingart.
We report the rare case of sudden knee pain due to fracture of the total knee replacement nine years after implantation. Fracture occurred because of subsequent osteolysis due to polyethylene wear.
Computer aided surgery has become established in the clinical routine over the past years. There are some very good studies which show that navigation optimizes reconstruction of the leg axis in total knee replacement. The question of why outliers occur in spite of navigation has to be asked. It is clear that total knee replacement is not only a bony procedure, but the soft tissues have an immense influence on postoperative stability of the prosthesis over the full range of movement. Current navigation systems allow visualization of the leg axis and size of the extension and flexion gap, and support the surgeon during soft tissue management. The current paper shows how the anatomic approach and the position of the patella influence soft tissue tension and support the surgeon during release of soft tissues in severe leg axis deformities.
Recognizing the rising number of primary total knee arthroplasties (TKA) over the last decade, one may assume an increasing number for revisions after a certain time delay. Studies showing a rate of only 78% satisfied patients provide a hint that there is still room for improvement. Therefore, it seemed worthwhile to evaluate the benefits of the computer assisted technique in revision TKA and compare the alignment results with the conventional technique. In a prospective study, 120 patients were operated for revision TKA using either the Vector-Vision navigation system (n=60) or the conventional technique (n=60). The axial limb alignment was evaluated on standardized pre- and postoperative full length weight-bearing radiographs and the variation of the joint line was determined by the method of Figgie from 1986.A precise reconstruction of the mechanical limb axis was achieved in 57/60 Patients (95%) in the computer assisted group and in 48/60 (80%) in the conventional group. A reconstruction of the joint line with a variation of less then 4 mm was achieved in 47/60 (78%) in the computer assisted and in 33/60 (55%) in the conventional group. Revision TKA remains a challenging procedure for the surgeon. Modern navigation systems offer additional information intraoperatively and might therefore simplify the procedure. In particular, the adjustment of the extension and flexion gap and the reconstruction of the joint line the results were superior. Furthermore, the use of a CT-free navigation system provides a significant improvement of prosthesis and leg alignment in revision TKA.
INTRODUCTION: Symptomatic deep vein thrombosis is a serious complication after total knee arthroplasty, with a risk of about 4-5% despite prevention with herparin. Aim of the current study was to find out about the actual status of thrombosis prophylaxis in Germany after total knee replacement. MATERIAL AND METHODS: In a countrywide survey 470 German trauma and orthopaedic surgery departments were asked about their prophylactic procedures addressing deep vein thrombosis after total knee replacement. RESULTS: 98% perform prevention of thrombosis with low-molecular-weight heparin, 2% use unfractioned heparin. Low-molecular-weight heparin is applicated in standard doses in 48% and in 44% according to patient's weight. In 82% the prophylaxis is begun the night before surgery. The therapy is carried out for 4.7 weeks in mean. 96% use graduated compressions stocking as additional therapeutic option. CONCLUSION: Our survey shows that most of the surgeons perform prevention of deep vein thrombosis according to the official guidelines.
In a prospective randomised clinical study acetabular components were implanted either freehand (n = 30) or using CT-based (n = 30) or imageless navigation (n = 30). The position of the component was determined post-operatively on CT scans of the pelvis. Following conventional freehand placement of the acetabular component, only 14 of the 30 were within the safe zone as defined by Lewinnek et al (40 degrees inclination sd 10 degrees ; 15 degrees anteversion sd 10 degrees ). After computer-assisted navigation 25 of 30 acetabular components (CT-based) and 28 of 30 components (imageless) were positioned within this limit (overall p < 0.001). No significant differences were observed between CT-based and imageless navigation (p = 0.23); both showed a significant reduction in variation of the position of the acetabular component compared with conventional freehand arthroplasty (p < 0.001). The duration of the operation was increased by eight minutes with imageless and by 17 minutes with CT-based navigation. Imageless navigation proved as reliable as that using CT in positioning the acetabular component.
The last five years have seen the rapid development of computer assisted surgery (CAS) in total knee replacement (TKR). Many surgeons perform TKR using navigation systems, which offer user-friendly workflows and reproducible results. A number of level 1 and 2 studies, according to evidence-based medicine criteria, have demonstrated that navigation in TKR allows a more precise implantation of the prosthesis, though CAS still requires an experienced surgeon and is time consuming. Nevertheless, 30% of surgeons in Germany who perform TKR have used navigation. It is still not known whether this new technique improves the longevity of TKR, however, and we therefore performed a meta-analysis to assess the results of this new health care technology.
INTRODUCTION: Precise reconstruction of leg alignment offers the best opportunity for achieving good long-term results in total knee arthroplasty (TKA). It was the aim of this study to evaluate the bone-cutting process as a potential source of inaccuracy in TKA. MATERIALS AND METHODS: In a consecutive series of 50 computer-assisted TKAs, cutting errors, which were defined as a difference between the cutting block position before sawing and the achieved resection plane afterwards, were measured for the distal femur and proximal tibia resection. Measurements were performed using a CT-based navigation system. RESULTS: For the distal femoral cut, there was a mean varus/valgus deviation of 0.6 degrees (SD+/-0.5 degrees ) and a mean flexion/extension deviation of 1.4 degrees (SD+/-1.3 degrees ). For the proximal tibia, varus/valgus alignment showed a mean deviation of 0.5 degrees (SD+/-0.5 degrees ). The mean sagittal variability was 1.0 degrees (SD+/-0.9 degrees ). Differences between the frontal and the sagittal plane were significant. CONCLUSION: To minimize cutting errors, techniques and instruments are needed which enable a more stable fixation of the cutting blocks or even more appropriate preparation instruments. Using a computer-assisted technique, the surgeon is aware of cutting errors occurring at each point of the operation and will therefore be able to correct these errors during surgery, while he is not aware of those errors with the conventional TKA technique.
Previous reports have described the potentially compromising effect of a high tibial osteotomy (HTO) on the results of a subsequent total knee arthroplasty (TKA). Although the reasons are not clear, some authors reported problems in soft-tissue balancing. In a prospective study, 22 patients with an average interval of 5.8 years after closed-wedge HTO were operated for TKA. All operations were performed with a CT-free navigation system, and measurements of the extension and flexion gap were assessed. The intraoperative data were compared to a control group of 100 consecutive computer-assisted TKA without previous osteotomy. In the study group, a highly significant shift towards a medial opening of the flexion gap between the posterior condylar line and the tibial resection (study group 0.4+/-4.7 degrees medial opening versus control group 3.4+/-3.3 degrees lateral opening, p<0.001) was observed. In the study group, 10/22 showed a medial opening of the flexion gap compared to 11/100 in the control group. Surgeons should be aware of difficulties in soft-tissue balance in TKA following HTO, especially for the flexion gap configuration and the axial rotation of the femoral component.
In a prospective study, two groups of 20 unicompartmental knee replacements (UKR) each were operated either using a CT-free navigation system or the conventional minimal invasive technique. Radiographic assessment of postoperative alignment was performed by long-leg coronal and lateral radiographs. The results revealed a significant difference between the two groups in favor of navigation. In the computer-assisted group, 95% of UKRs were in a range of 4-0 degrees varus (mechanical axis) compared with 70% in the conventional group. The only inconvenience was a prolonged operation time (+19 min). Due to the limited exposure, the navigation system is helpful in achieving a more precise component orientation. The danger of overcorrection is diminished by real-time information about the leg axis at each step during the operation.
Restoration of the mechanical limb axis and accurate component orientation are two major factors affecting the long-term results after total knee replacement (TKR). Different navigation systems are available to improve the outcome. Image-based systems require pre-operative CT scans, while non-image-based systems gain all necessary information intra-operatively during a registration process. We studied 130 patients who received a TKR either using the CT-based (Knee 1.1) or the CT-free module (CT-free Knee 1.0) of the BrainLAB Vector-Vision Navigation System. Post-operative leg alignment and component orientation was determined on long-leg coronal and lateral X-rays. Sixty of 65 patients in the CT-based group and 63/65 patients in the CT-free group had a post-operative leg axis between 3 degrees varus/valgus. No significant differences were found for varus/valgus orientation of the femoral and tibial components.
INTRODUCTION: The operative treatment of a secondary gonarthrosis due to RA claims high quality in soft tissue balancing and accurate alignment in total knee arthroplasty (TKA) which are essential for good long-term results. The efficiency of an imageless computer-assisted implantation in TKA was evaluated and compared with conventional technique. METHOD: The authors implanted each 40 TKA either using the imageless computer-assisted or classical surgeon-controlled technique. The quality of implantation was studied on postoperative long leg coronal and lateral x-rays. RESULTS: A postoperative leg axis between 3 degrees varus and 3 degrees valgus was obtained in 37 patients (92.5%) in the study group and 30 patients (75%) in the control group. Complications influencing the clinical outcome did not occur. CONCLUSION: The use of the imageless Vector-Vision navigation system provides the patient a good chance for longterm survival. Especially the ligament balancing tool appears to be useful. Cutting errors can be detected and intraoperatively corrected.
AIM: Reconstruction of insufficient anterior cruciate ligament (ACL) has become a standard operative procedure. Still, graft choice and fixation technique are discussed controversially. The objective of this study was to ascertain the current treatment of ACL reconstruction in german orthopedic surgery and trauma centers. METHODS: A total of 250 trauma and 220 orthopedic surgery centers were asked for their treatment strategy and postoperative procedure of ACL reconstruction in an anonymous German-wide survey. RESULTS: 230 questionnaires (48.9 %) were returned for evaluation. 90.4 % of the surgeons reconstruct the anterior cruciate ligament. Patellar tendon is used by 73 % of orthopedists and 80.7 % of trauma surgeons. Reconstruction with semitendinosus tendon transplant is performed by 71.6 % of the orthopedists and 41.6 % of trauma surgeons. For tibial fixation the interference screw is as well of the semitendinosus tendon as of the patellar tendon the most common technique. In about 30 % each the femoral fixation results from interference screw and endo-button. CONCLUSION: There is still no generally accepted intra- and postoperative strategy for reconstruction of ACL. Reconstruction with semitendinosus tendon becomes more common.
Restoration of neutral alignment of the leg is an important factor affecting the long-term results of total knee arthroplasty (TKA). Recent developments in computer-assisted surgery have focused on systems for improving TKA. In a prospective study two groups of 80 patients undergoing TKA had operations using either a computer-assisted navigation system or a conventional technique. Alignment of the leg and the orientation of components were determined on post-operative long-leg coronal and lateral films. The mechanical axis of the leg was significantly better in the computer-assisted group (96%, within +/- 3 degrees varus/valgus) compared with the conventional group (78%, within +/- 3 degrees varus/valgus). The coronal alignment of the femoral component was also more accurate in the computer-assisted group. Computer-assisted TKA gives a better correction of alignment of the leg and orientation of the components compared with the conventional technique. Potential benefits in the long-term outcome and functional improvement require further investigation.
Total elbow arthroplasty has become a reliable treatment option for patients with rheumatoid arthritis as well as primary or posttraumatic arthrosis. The aim of this study is to present the indications, operative technique and results for the implantation of an Acclaim elbow prosthesis. Case reports are given to demonstrate the indications for prosthesis implantation. Furthermore, the follow-up results are reported for 65 patients after implantation of an Acclaim prosthesis. Pre- and postoperative pain were evaluated using the visual analogue scale. The pain level decreased from 8.0 to 2.3 postoperatively. After implantation of an elbow prosthesis, there was a significant improvement in the range of motion. The mean flexion increased from 103 degrees preoperatively to 140 degrees postoperatively. An increase of 10 degrees was found for both supination and pronation. Complications included temporary ulnary nerve irritation in seven patients, intraoperative fractures in four cases and postoperative elbow dislocation in one case. In conclusion, total elbow arthroplasty results in a reduction of pain and an improvement in elbow movement. However, selection of the right patient is important. Patients are advised not to lift heavy objects or to perform hard physical work. If patients' compliance can not be ensured preoperatively, no total elbow arthroplasty should be performed.
Accurate leg alignment is one important factor for long term survival in total knee arthroplasty (TKA). The aim of this study was to determine the accuracy of a CT-based navigation system in restoration of the leg axis. 80 TKA (P.F.C.-Sigma--DePuy) were implanted either using a CT-based navigation-system or the conventional technique. There were no significant differences between the groups according to the preoperative leg deformity. Accuracy of implantation was determined on postoperative long-leg coronal and lateral x-rays. A postoperative leg axis between 3 degrees varus and 3 degrees valgus was obtained in 35/40 patients (88%) in the computer assisted and 28/40 patients (70%) in the conventional operated group. A higher precision in the sagittal plane was seen for the tibial (computer assisted: 3.9 +/- 2.2 vs. conventional TKA 1.3 +/- 5.8) and the femoral component (computer assisted: 3.5 +/- 2.3 vs. conventional TKA 6.9 +/- 3.6). The use of the CT-based VectorVision-System allows a significant improvement in the accuracy of implantation in TKA. The CT-based module has the advantage of a precise preoperative planning and a useful documentation and control tool for each important step. On the other hand there are additional costs and time consuming logistics.
Musculoskeletal disorders represent the main cause for absenteeism. To determine the disorders exactly, a multistep inventory of examinations was developed. The method of diagnostics may be an indicator of the quality of occupational medical management. It may improve the availability of health data related to working conditions and may increase the chances of goal-oriented prevention in the field of working conditions as well as in the field of behavior. In addition, the standardized recording of data provides an opportunity for evaluation in epidemiological studies, which may be organized as longitudinal studies to look for the development of musculoskeletal disorders over time.
Typical back problems as well as complaints in the shoulder-arm-hand system are increasing as the volume of sedentary office work at the computer screen rises. Various legal rules precisely define preventive measures. However, basic orthopedic-biomechanical principles are not being taken into consideration. Orthopedists as well as occupational physicians are equally challenged to enforce those legal guidelines by beginning to raise awareness of the principles and thus contributing towards improvement of working conditions.
INTRODUCTION: There is no general agreement on the operative treatment of displaced proximal humeral fractures. While T-plate fixation was the method of choice until the end of the 1980s, minimally invasive techniques have been favoured during the past decade. The indication for primary shoulder prosthesis is controversial. The purpose of this report was to evaluate the scientific evidence of current treatment recommendations. METHODS: Relevant articles were retrieved from "Medline" and "Knowledge-Finder" using the combined search strategy for the keywords "proximal humerus" and "fracture". Retrieved articles were evaluated according to the criteria of evidence-based medicine. RESULTS: The analysis retrieved 3 randomized, 4 prospective, and 26 retrospective studies and a number of review articles relevant to the subject. Limitations of most publications were due to small study populations, differences in patient selection and fracture classification as well as measurements of outcome. According to these studies good functional results can be achieved in dislocated two-part fractures treated with minimal osteosynthesis in the elderly and T-plate fixation in younger patients. For three- and four-part fractures minimally invasive techniques seem to be more favourable in the elderly. However, there is some evidence that alternative therapies such as conservative treatment and plating can be successful in defined populations. A general indication for primary implantation of a prosthesis in four-part fractures in the elderly is not supported by the literature. CONCLUSION: We conclude from our analysis that the scientific evidence for treatment recommendations of displaced proximal humeral fractures is still limited.