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At least 127 records · Page 7Linked to original sources
PubMed2001

A study on beams passing through hip prosthesis for pelvic radiation treatment.

PURPOSE: To study the dose distributions at the interface due to the presence of a metal implant; to show the dose distributions in combined fields in the presence of hip prostheses; and to demonstrate the capabilities and limitations of a conventional system. METHODS AND MATERIALS: Perturbations in the dose distribution caused by a hip prosthesis can result in unacceptable dose inhomogeneities within the target volume and in regions where tissues interface with implant. The Monte Carlo technique and a conventional treatment planning system are used to calculate the dose distributions. RESULTS: Dose increases of 15% in tissue are seen at the interface between metal implant and tissue. Dose reductions of 5-25% or 10-45% are observed in the shadow of the hip prosthesis made of 0.5-3-cm-thick titanium or steel alloy respectively. We compared predicted dose distribution between the Monte Carlo simulation and a commercial treatment planning system (CADPLAN). We found that CADPLAN underestimated the attenuation of hip prostheses. This has led to overestimation of the target dose by 14% for a typical four-field box technique. CONCLUSIONS: An acceptable dose distribution can be achieved with a proper lateral beam weighting and compensation using an eight-field technique. The beam compensation may be applied to achieve an adequate target dose.

Hip Prosthesis↗
PubMed1986

[Replacement of a failed total hip prosthesis].

At the present time, apart from infectious complication, failed total hip prosthesis essentially consist of detached prosthesis. On the basis of their experience of eight thousand arthroplasties, including more than 6,000 Charnley prosthesis, performed over a period of 18 years, the authors propose three basic principles designed to ensure a long term satisfactory result: steel on polyethylene prosthesis, diameter 22 and fixation with acrylic cement. They consider that this approach can offer a second chance to patients with a detached prosthesis, especially when the technique of the first arthroplasty was faulty or if a poor quality prosthesis was used. The authors' experience has confirmed that the second operation should aim to restore an arthroplasty as close as possible to normal anatomy. The authors have satisfactorily achieved this aim by the wide use of homografts.

Hip Prosthesis↗
PubMed2004

Successful treatment of Staphylococcus epidermidis hip prosthesis infection with oral linezolid.

OBJECTIVE: To report a case of Staphylococcus epidermidis infection of a hip prosthesis successfully treated with oral linezolid. CASE SUMMARY: A 46-year-old woman developed methicillin-resistant S. epidermidis (MRSE) infection of her prosthetic hip. She received oral linezolid 600 mg twice daily for one month; after that time, the biological inflammatory markers returned to normal. DISCUSSION: One of the most serious complications of arthroplasty is joint prosthesis infection. It is mainly caused by gram-positive bacteria, in particular those of the genus staphylococcus. The increasing prevalence of gram-positive cocci that are resistant to antimicrobial agents has complicated the treatment of serious infections. CONCLUSIONS: Oral linezolid appears to be an effective and well-tolerated treatment option for hip prosthesis infections due to MRSE.

Acetamides↗
PubMed1992

[A comparative study of the characteristics of femoral hip prosthesis heads--study and results ceramic-coated hip joint heads of titanium].

Today, only hard/soft cup and femoral head combinations are employed for hip joint prostheses. Highly polished ceramic is a material with very good tribological properties for femoral heads, being highly resistant to mechanical wear and tear, and highly resistant to chemical reactions in the biological environment. The advantage of metal heads, in contrast, undoubtedly lies in their resistance to breakage and the ease with which their geometry can be modified with respect, for example, to antirotation angle and neck length. The ideal material for femoral heads is a combination of the two materials. The new multi-layer combination of titanium-niobium oxide/nitride ceramic coating applied to a prehardened titanium head combines the positive material properties in an ideal manner. Femoral heads made of CoCrMo, oxide-hardened titanium, aluminium oxide or multilayer titanium-niobium ceramic were compared by means of friction an wear and tear tests. The TiNb-ceramic-metal heads showed similar abrasion at the surface as the ceramic heads. At the high loads of more than 400 kp, which may also be reached under physiological conditions, the specially coated titanium-ceramic heads proved to be superior in terms of resistance to fracture and tribological properties.

Biomechanical Phenomena↗
PubMed1991

[Luxation of total hip prosthesis. Mathematic modelization, biomechanical approach].

Two particular aspects of total hip prosthesis dislocations were assessed by a mathematical method. A theoretical analysis of the intra-prosthetic motions, in function of the architectural parameters was presented as well as a biomechanical approach of the dynamic stability of the prosthetic hip during the flexion. It showed then two potential causes of dislocations: malposition dislocations, due to the block-effect of the femoral neck on the acetabular border; the position of the acetabular cup appeared as predominant for a given type of prosthesis too anteversed and/or too vertical, it limited the movement of external rotation at the origin of anterior dislocations; too horizontal and not enough anteversed it obstructed the flexion, especially if there was an association of internal rotation and adduction, the dislocation was then posterior. dislocation by muscular discoaptation. Here, the dislocating forces, during the flexion of the hip, were greater than the coaptation phenomenon which became precarious by the arthroplasty and quantified, in our model, by a multifactorial parameter translating the behaviour of the gluteus medius muscle during flexion.

Biomechanical Phenomena↗
PubMed1983

Replacement of femoral head endoprosthesis with total hip prosthesis. A report of five cases with problems of management.

Five cases who had endoprosthesis implanted for medial fracture of the neck of the femur are reported. All of them developed late complications that required replacements of endoprosthesis with total hip prosthesis. Complications included wearing of both joint cartilage and subchondral bone of the acetabulum, osteoporosis of the proximal end of the femur and fracture of the femur and the level of the endoprosthesis. Several problems of surgical management ensued. This experience strengthens the author's opinion that other forms of treatment--reduction in traction and nailing or total hip prosthesis--should be tried first also in particular cases of chronologically aged, but physically healthy patients with medial fractures of the neck of the femur.

Aged↗
PubMed1979

[Total hip prosthesis. Current indications (author's transl)].

The various problems posed by total hip prosthesis are first described. The authors then analyse the various parameters which should guide the choice of this technique which must be used only when all other solution have failed. The recent development of prostheses without cement has made it possible to widen the application of this surgery to younger patients. Two special cases are finally reported: the role of total prostheses in the treatment of sequelae of fractures of the acetabulum, and in disarthrodesis of the hip with insertion of a total prosthesis.

Aged↗
PubMed2002

The effect of a metal hip prosthesis on the radiation dose in therapeutic photon beam irradiations.

Prostate and cervical cancer patients are often treated with external X-ray beams of bi-lateral incidence. Such treatment may incur some dose effect that cannot be predicted precisely in commercial treatment planning systems (TPS) for patients having undergone total hip replacement. This study performs a Monte Carlo (MC) simulation and an analytical calculation (convolution superposition algorithm which is implemented in ADAC TPS) of a 6 MV, 5 x 5 cm2 X-ray beam incident into water with the existence of hip prosthesis, e.g. Ti6A14V and CoCrMo alloy. The results indicate that ADAC TPS cannot precisely account for the scatter and backscatter radiation that a metal hip prosthesis causes. For percent depth dose (PDD) curves, the maximum underdosage of ADAC TPS up to 5mm above the interface between dense material and water is 5%, 20% and 27% for PDD(Bone), PDD(Ti) and PDD(Co), respectively. The dose re-buildup, which occurs behind the hip region, becomes more and more obvious for denser medium existed in water. Increasing inhomogeneity also enhances the underdosage of ADAC for greater depth (> 10cm), as the figures of nearly 2% in PDD(Bone), PDD(Ti) and 4-5% in PDD(Co) reveal. Overestimating the attenuated power of high-density non-water material in ADAC TPS causes this underdosage. For dose profiles, no significant differences were found in Profile(Bone) at any depth. Profile(Ti) reveals that MC slightly exceeds ADAC at off-axis position 1.0-2.0 cm. Profile(Co) reveals this more obviously. This finding means that scatter radiation from these denser materials is significant and cannot be predicted precisely in ADAC.

Algorithms↗
PubMed1992

Motion of the bipolar hip prosthesis components. Friction studied in cadavers.

It has been postulated that most hip motion occurs at the inner bearing in bipolar hip prosthesis. However, radiography and cineradiography analyses have shown that the inner bearing is not always the primary articulation. We studied the frictional behavior of bipolar prosthesis and Austin-Moore prostheses and the motion of the bipolar prosthesis using a pendulum apparatus. The primary articulation was altered according to the amount of loading. When a load of 10 kg was applied to the joint, motion occurred at both bearings with friction coefficients 0.061 at the inner bearing and 0.026 at the outer bearing. With loads of over 20 kg, the outer bearing was the primary articulation. The inner bearing was the dominant articulation only when the acetabular cartilage had been removed. Our results suggest that the motion of bipolar prostheses occurs mainly at the outer bearing during normal walking, and that this prosthesis cannot be expected to reduce wear of articular cartilage.

Biomechanical Phenomena↗
PubMed2002

Comparison of 99mTc ciprofloxacin, 99mTc white blood cell and three-phase bone imaging in the diagnosis of hip prosthesis infections: improved diagnostic accuracy with extended imaging time.

The purpose of this study was to compare the utility of 99mTc labelled ciprofloxacin (Infecton) imaging with the 99mTc white blood cell and three-phase bone imaging procedures for identifying hip prosthesis infection. We studied 30 symptomatic patients in whom infection was confirmed in eight and excluded in 22 cases based on clinical and microbiological findings. 99mTc ciprofloxacin images were obtained at 1, 4 and 24 h after the injection of the tracer, and the data were compared to those obtained from 99mTc leukocyte and three-phase bone imaging. The 99mTc ciprofloxacin imaging correctly identified all true infections. In 13 (59%) of the non-infected patients, non-specific uptake of 99mTc ciprofloxacin was found in the 1-h and 4-h images, which disappeared, however, in the 24-h images. When the early and late 99mTc ciprofloxacin images were compared, the specificity was found to improve from 41% to 95%, positive predictive value from 38% to 89%, and the diagnostic accuracy from 57% to 97%. The accuracy of the conventional 99mTc leukocyte imaging was 90%. Dynamic bone imaging also yielded abnormal findings in all the infected patients although also in 23% of the non-infected patients. Current data indicate that 99mTc ciprofloxacin is a useful method for confirming hip prosthesis infection. The diagnostic efficiency of this method is improved when the imaging time is extended to 24 h post-injection of the tracer.

Adult↗
PubMed1987

Development of alumina ceramic bipolar hip prosthesis and clinical application.

The concept of the bipolar type prosthesis is that the articular motion is observed primarily between the HDP bearing insert and the inner head, thereby avoiding the greater frictional shear force between the prosthetic head and acetabulum found with the traditional one piece endoprosthesis. A newly developed ceramic bipolar hip prosthesis utilizes an outer head composed of bio-inert fine alumina ceramic rather than a metal head. The mechanical strength of this prototype bipolar hip prosthesis was tested with static load and impact force, and the dynamic fatigue strength was also tested with repeated loads. Results were judged to show that the device has strength adequate for clinical use. The hip prostheses has been clinically applied in replacement of the femoral head of a neck fracture, femoral head necrosis and osteoarthritic hip. Finally, using a mathematical model, the so-called self-centering effect due to center offset between outer and inner heads is discussed.

Adult↗
PubMed1990

Grosse-Kempf nail combined with a Scan hip prosthesis.

A Grosse-Kempf nail was used with a Scan femoral hip prosthesis to manage a patient who sustained a pathological fracture of the neck of the femur after the previous introduction of the interlocking nail for a similar fracture of the lower end of the femur.

Aged↗
PubMed1987

Clinical evaluation of 104 hip resection arthroplasties after removal of a total hip prosthesis.

Functional results of resection arthroplasty are currently considered poor. In 104 hip prosthesis removals after either septic or aseptic loosening, pain, walking, joint motility, life style, and patient's opinion were evaluated. A satisfactory result was recorded in 72% of cases. Prognosis is poorer in patients who are young, have septic loosening, and have poor residual mobility. Resection arthroplasty should be considered a salvage procedure in cases of septic loosening and/or bone stock deficiency after a failed total hip arthroplasty.

Adult↗
PubMed1984

Acetabular erosion and the Monk "hard top" hip prosthesis.

Nine cases of acetabular erosion following insertion of the Monk "hard top" hip prosthesis for subcapital fractures are presented. All of these patients had significant symptoms and represented 5% of the total group. In our experience acetabular erosion has proved to be a significant complication of the Monk "hard top" prosthesis.

Acetabulum↗
PubMed1983

[Spongiosa plug for closing the medullary cavity. A technical variation in the implanting of total hip prosthesis].

A modification and the technical details for the implantation of total hip prosthesis is reported. In order to improve stabilisation of the femoral shaft component of the endoprosthesis and to prevent the progress of bone cement also in the distal femoral part of the marrow cavity, the intramedullary cavity is blocked with a bone cylinder prepared from the resected femoral head. Using a special instrument, this bone block is introduced into the intramedullary cavity before filling up the proximal femur with bone cement. Bone cylinders can be prepared and preserved in a bone bank for use whenever necessary.

Bone Transplantation↗
PubMed2004

Why does outer joint motion predominate in bipolar hip prosthesis? Experimental and clinical studies.

BACKGROUND: Theoretically, the motion of a bipolar hip prosthesis is most likely to occur at the inner joint if the frictional coefficients are equal at both surfaces. However, many studies have suggested that most motion occurs at the outer joint. MATERIAL AND METHODS: We performed an analysis of motion in a cadaveric bone model and in 50 patients during fluoroscopic examination, to determine how the motion is distributed between the two joints and what factors contribute to this distribution. RESULTS: The motion distributions varied widely between the patients. However, there was a relative pre-ponderance (63-90%) of outer motion in all directions of leg movement in addition to a persistent coexistence of motion at both joints in 44 of 50 patients. This preponderance of outer motion was the result of an early impingement of the acetabular cup and structural differences between the two joints. INTERPRETATION: An adjustment of the positive eccentricity and a decrease in the frictional torque of the inner joint as a result of better lubrication and smoothness can be expected to improve the motion distribution, thus reducing the amount of acetabular erosion.

Adult↗