Search PubMed⌕ Search

Biomedical subjects

R Gradinger

Publications and source records attributed to R Gradinger.

At least 19 recordsLinked to original sources
PubMed2006

[Typical injuries seen in football players].

Injuries seen in football players mainly affect the knee and ankle joints and muscles. The causes include chronic overstrain and traumatization usually resulting from physical contact between opponent players. Torsional trauma of the joints results in excessive stressing of the capsular ligaments, potentially leading to rupture of the structures involved. Therapeutic options range from conservative measures to reconstructive or prosthetic surgery. While muscular injuries have a good prognosis with regard to the chances of continuing sports activities, injuries to ligaments often enforce a lengthy pause from sports. Extensive injuries to cartilages can terminate a player's sporting career. However, new procedures that take account of physiological biomechanics, together with the further development of surgical technologies now often allow players to regain their pre-injury level of fitness. Specific rehabilitation is a major therapeutic means of preventing further injury.

Ankle Injuries↗
PubMed2006

[Soft tissue sarcoma--epidemiology, diagnosis and treatment].

On account of the considerable variability of the clinical situation, treatment of soft tissue sarcoma requires an individually oriented multimodal approach. In the case of patients with superficial low-grade tumors measuring less than 5 cm in diameter, resection alone is usually adequate. In the event of medium-grade lesions, resection with negative margins, resection in combination with radiotherapy achieves excellent local control rates associated with an overall survival rate of almost 80%. In patients with high-grade sarcomas measuring more than 5 cm in diameter, local control can be achieved with resection and radiotherapy, although every second such patient develops metastases. For patients with local recurrence, further resection should be considered/performed. Radiotherapy is all the more effective, the smaller the postoperative tumor cell burden.

Combined Modality Therapy↗
PubMed2006

[Therapy of arthrofibrosis after total knee arthroplasty].

Arthrofibrosis is one of the most common complications after total knee arthroplasty with an overall incidence of approximately 10%. Nevertheless, published data are rare and clinical trials mostly include small and heterogeneous patient series resulting in controversial conclusions. Clinically, arthrofibrosis after knee arthroplasty is defined as (painful) stiffness with scarring and soft tissue proliferation. Differentiation between local (peripatellar) and generalized fibrosis is therapeutically relevant. Histopathology typically shows subsynovial fibrosis with synovial hyperplasia, chronic inflammatory infiltration, and excessive and unregulated proliferation of collagen and fibroblasts. Diagnostic strategies are based on the exclusion of differential causes for painful knee stiffness, and especially the exclusion of low-grade infections represents a diagnostic challenge. Early and intensive physiotherapy combined with sufficient analgesia should be initiated as a basic therapy. The next therapeutic steps for persisting arthrofibrosis include closed manipulation and open arthrolysis. Arthroscopic interventions should be limited to local fibrosis. Revision arthroplasty represents a rescue surgery, often associated with recurrence of fibrosis. Prevention of arthrofibrosis by sufficient analgesia and early physiotherapy remains the best treatment option for painful stiffness after knee arthroplasty.

Arthroplasty, Replacement, Knee↗
PubMed2006

[Soft tissue carcinoma. Epidemiology, diagnostics and therapy].

The treatment of soft tissue sarcoma requires an individually tailored, multimodal therapy due to the high variability in the clinical situation. Resection is the usual treatment for patients with superficial, low grade tumors with a diameter of <5 cm. For intermediate grade, differentiated lesions, resection with negative resection edges combined with radiotherapy attains an almost 80% total survival rate. For patients with high grade sarcoma of >5 cm, local control can be attained by resection and radiotherapy, however every second patient will develop metastases. Patients with a local recurrence should consider a new resection. Radiotherapy is the more effective the lower the remaining postoperative tumor burden.

Biopsy↗
PubMed2005

[Diagnosis specific differences in knee joint geometry. A challenge for the correct axial implantation of long stems in total knee arthroplasty].

BACKGROUND: Arthrotic deformities with changes in knee geometry can produce difficulties in implanting long stem knee prosthesis systems using intramedullary alignment. They can result in incorrect lower limb axis and prosthesis positioning. The aim of the presented study was to measure knee geometry in patients with varus and valgus gonarthrosis in order to define diagnosis related differences. METHODS: A total of 75 patients with indication for total knee arthroplasty were divided in two groups using the weight bearing lower limb axis: patients with varus gonarthrosis (n=43) and with valgus gonarthrosis (n=32). Angles and extensions, important for knee prosthesis implantation, were measured, digitalized and analyzed. The results were investigated for diagnosis specific differences. RESULTS: After regulation of the measured extension in mean femur/tibia lengths, significant diagnosis specific differences were found: femur condyles were widened towards pathologic weight bearing (P<0.044), and the mechanical tibia axis of the varus gonarthrosis group is transferred to the lateral side (P<0.046) and in projection over the lateral internal cortical substance. CONCLUSION: The significant differences in deformed arthrotic knees indicate that for an optimal postoperative result the use of standard implants is not always sufficient. Modular knee prosthesis systems can provide adequately for individual demands.

Adult↗
PubMed2005

[Fluoroscopy-based 3D navigation of complex correction osteotomies at the proximal femur].

BACKGROUND: Despite great advances in hip alloarthroplasty there are still numerous indications for joint-saving procedures such as correction osteotomies. Often these procedures include complex 3D rearrangements of the proximal femur, which are for the surgeon technically very demanding. The project aim was to develop a precise intraoperative virtual 3D planning tool including a detailed biomechanical analysis and enable the surgeon to realize exactly this plan by using computer-assisted techniques. METHODS: Using only two different angled fluoro frames a simplified femoral model was inversely constructed. For navigation a passive optical system was used with a C-arm calibration kit and PC-based software. For in vitro evaluation complex osteotomies were performed on ten femora under simulated OR conditions. RESULTS: The mean difference between the planning and real surgical outcome for the wedge size was less then 2 degrees and for the femur head center position less then 4 mm. No implant penetrated the femur neck isthmus. CONCLUSION: Without changing the standard operative procedure the method can be of high clinical importance to improve planning accuracy and consecutive operative realization for precise fragment positioning and plate location without penetrating the isthmus of the femoral neck. And -- besides precision -- it can potentially help to reduce intraoperative complications such as implant penetration and minimize X-ray use.

Computer Simulation↗
PubMed2005

[Evaluation of the assembling and retention forces of constraint liners for total hip replacement].

Dislocation is a severe complication after total hip replacement which may cause revision surgery in some cases. The use of constraint inserts that are coupled to the femoral head by a snapping mechanism provides an opportunity for treatment of recurrent dislocations. This study was aimed to investigate the assembling and retention forces of a specific constraint liner. Using a universal testing machine the assembling forces were determined for head sizes of 28 and 32 mm and the clinically mostly used as well as the maximum cup size. Subsequently, under variation of load direction and pull-out velocity the retention forces were investigated. For primary assembly of the head the required compressive forces were in a range from 197 N and 283 N depending on head and cup size (each size n = 3). Repeated assembly led to a decrease of these forces up to 29%. The retention forces always were slightly below the assembling forces, i. e. forces to remove the heads from the inserts were between 183 N and 230 N (each size n = 3). Repeated disconnection caused a decrease of the retention forces up to 16%. An increase of load velocity as well as an oblique load direction resulted in an enhancement of the retention forces. For all investigated implant sizes the retention force for the femoral head was approximately ten-times less than the interface strength between the insert and the metal-back. In case of correct implant handling the risk of disconnection between the tested constraint insert and the corresponding metal-back has not to be considered in clinical practice.

Acetabulum↗
PubMed2003

[Congenital clubfoot].

Owing to the relatively high incidence of this condition (2 in 1,000 neonates) and the poor functional outcome of inadequate treatment, clubfoot represents a major clinical problem. Although its etiology is not fully known, modern three-dimensional analyses have led to a better understanding of the pathomorphology and provide a new basis for a differentiated therapeutic strategy. Of central importance is early diagnosis and immediate postpartum initiation of primarily conservative treatment taking the form of intensive redressment measures. Depending on the residual deformity, an appropriate surgical procedure aimed at achieving complete correction should be done between the age of 4 to 6 months. To ensure a lasting positive outcome, rigorous follow-up physiotherapeutic treatment and close surveillance are essential.

Age Factors↗
PubMed2003

[Carbon fiber-reinforced plastics as implant materials].

Carbon fiber-reinforced plastics have been used clinically as an implant material for different applications for over 20 years.A review of technical basics of the composite materials (carbon fibers and matrix systems), fields of application,advantages (e.g., postoperative visualization without distortion in computed and magnetic resonance tomography), and disadvantages with use as an implant material is given. The question of the biocompatibility of carbon fiber-reinforced plastics is discussed on the basis of experimental and clinical studies. Selected implant systems made of carbon composite materials for treatments in orthopedic surgery such as joint replacement, tumor surgery, and spinal operations are presented and assessed. Present applications for carbon fiber reinforced plastics are seen in the field of spinal surgery, both as cages for interbody fusion and vertebral body replacement.

Carbon↗
PubMed2002

[Mechanical studies of lumbar interbody fusion implants].

In addition to autogenous or allogeneic bone grafts, fusion cages composed of metal or plastic are being used increasingly as spacers for interbody fusion of spinal segments. The goal of this study was the mechanical testing of carbon fiber reinforced plastic (CFRP) fusion cages used for anterior lumbar interbody fusion. With a special testing device according to American Society for Testing and Materials (ASTM) standards, the mechanical properties of the implants were determined under four different loading conditions. The implants (UNION cages, Medtronic Sofamor Danek) provide sufficient axial compression, shear, and torsional strength of the implant body. Ultimate axial compression load of the fins is less than the physiological compression loads at the lumbar spine. Therefore by means of an appropriate surgical technique parallel grooves have to be reamed into the endplates of the vertebral bodies according to the fin geometry. Thereby axial compression forces affect the implants body and the fins are protected from damaging loading. Using a supplementary anterior or posterior instrumentation, in vivo failure of the fins as a result of physiological shear and torsional spinal loads is unlikely. Due to specific complications related to autogenous or allogeneic bone grafts, fusion cages made of metal or carbon fiber reinforced plastic are an important alternative implant in interbody fusion.

Biomechanical Phenomena↗
PubMed2002

Limb salvage with tumor endoprostheses for malignant tumors of the knee.

Data of 64 consecutive patients with malignant tumors of the knee treated with tumor endoprostheses between 1976 and 1996 were reviewed. The study was retrospective before 1990 and prospective since then. Four patients were lost to followup and are not included in the study. The average age of the remaining 60 patients was 33.2 years (range, 9-72 years). Fifty patients had surgery for primary sarcoma and 10 patients had surgery for metastases of carcinoma. In the patients in the sarcoma group, the probability of 5 years survival was 72% and 10 years survival was 69%. The overall clinical score of 47 patients with a followup more than 9 months was 81% using the evaluation system of the International Society of Limb Salvage. Fifty-eight reoperations were done in 29 patients because of complications. Twenty reoperations were attributable to soft tissue complications, 34 reoperations were because of mechanical problems related to the prostheses, and four were because of local tumor recurrence. The probability of survival of the leg of the patient after 10 years was 95%. Despite a high rate of complications after limb salvage with endoprostheses, the final clinical outcome usually was good.

Adolescent↗
PubMed2001

[Using robots in hip prosthesis implantation. Precision with the wrong concept?].

Robot-assisted milling permits more precise preparation of the proximal femur, without necessarily optimizing stem placement. Currently propagated implantation concepts involving maximized implant-cortical bone contact may result in major biomechanical disadvantages, such as unphysiological load transfer in the proximal femur and increased stiffening in this region and subsequent stress shielding. While equipment procurement and running costs are higher, evidence of longer prosthetic life over the long-term has not been forthcoming. Against this background, present efforts to propagate this system for general use in hip replacement surgery cannot be justified.

Arthroplasty, Replacement, Hip↗
PubMed2001

Acute confusional state in the elderly following hip surgery: incidence, risk factors and complications.

OBJECTIVE: To determine incidence and risk factors for the development of postoperative acute confusional state (ACS) in the elderly. DESIGN: A prospective cohort study. SETTING: University hospital. PATIENTS: One hundred and five consecutive patients without ACS at baseline who underwent hip surgery because of hip fracture or elective hip replacement. All patients were 60 years or older. MEASUREMENTS: All patients underwent preoperative and daily postoperative evaluation by a research psychiatrist. Standardized instruments were used for cognitive screening, baseline assessment of depression, screening for alcohol abuse, comorbidity, and functional status. ACS was diagnosed by using the Confusion Assessment Method (CAM). Additional medical data were taken from patients' charts and anaesthetic records. RESULTS: Postoperative ACS developed in 23.8% of the study sample, in 40.5% of the hip fracture group and in 14.7% of the hip joint replacement group. The prevalence was highest between postoperative days 2 and 5. Multiple logistic regression analysis demonstrated the following risk factors of ACS: higher age (OR = 1.14, 95% CI 1.07-1.22), prior cognitive impairment as measured by Mini-Mental State Examination (OR = 1.32 for each point less, 95% CI 1.06-1.64), depression (OR = 3.67, 95% CI 1.12-12.02), low educational level (OR = 3.59, 95% CI 1.14-11.25), and preoperative abnormal sodium (OR = 4.32, 95% CI 1.01-18.38). Other risk factors showing statistically significant differences in the univariate analyses were: living in nursing home, vision or hearing impairment, higher comorbidity, regular use of psychotropic drugs before admission, fracture on admission, preoperative leucocytosis. A considerable proportion of patients with ACS showed self-destructive behaviour postoperatively, whereas self-destructive behaviour was not observed among non-delirious patients. CONCLUSIONS: ACS is common among elderly hip surgery patients. The occurrence of ACS is influenced by several predisposing and precipitating factors. Further knowledge of these risk factors will contribute to the early identification of high risk patients and to the development of preventive measures.

Acute Disease↗
PubMed2001

[New compounds for improving wear behavior of a tumor knee endoprosthesis].

Wear of the central bushing made of ultra-high molecular weight polyethylene (PE-UHMW) of the hinged knee endoprosthesis of a tumour-resection system is the leading reason for revision. The aim of the study was to optimize the wear characteristics of the endoprosthesis on the basis of the tribological properties of new materials and an additional finite element (FE) calculation taking account of the given design. In screening tests the reference combination of PE-UHMW bushing and CoCr axis--used in the clinical setting--was first tested. The PE-UHMW bushing was then replaced by one made of each of the materials reinforced high-density polyethylene (PE-HD) and carbon fibre-reinforced epoxy resin (CFRP). In addition, a new material combination with an alumina ceramic bushing and a CFRP axis was investigated. In comparison with the reference combination PE-UHMW/metal, the combination of ceramic bushing and CFRP axis showed less wear. However, with the particular design of the prosthesis studied here, high mechanical loading applied experimentally resulted in mechanical failure. FE calculations confirmed these experimental results. Improvement of the wear characteristics of this specific implant caused therefore be achieved only by optimizing the bearing design.

Biomechanical Phenomena↗