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At least 163 records · Page 9Linked to original sources
PubMed2003

[Dislocated fracture of the lesser trochanter with malrotation of the stem after robot assisted implantation of a cementless hip prosthesis: a casuistic report].

This paper presents the case of a 63 year old female with a severe coxarthrosis. She got a robot assited implantation of a cementless hip prosthesis (Osteolock, Stryker-Howmedica, Mühlheim). As operation robot the CASPAR-System (Orto-Maquet, Rastatt) was used. Initially, the clinical progress of the patient was fine. She was nearly painfree within 14 days and showed an acceptable range of motion in the operated joint (flexion/ extension 90 degrees /05 degrees /00 degrees ). She was mobilized with crutches and 15 kg weight bearing at the operated leg. 3 weeks postoperative the patient complaint about increasing pain without trauma or intensification of the weight bearing. X-rays showed not only a dislocated fracture of the lesser trochanter, but also a sinking combined with a malrotation of the stem. A revision operation was necessary,where we implanted a cemented stem. Now clinical progress was completely satisfying.

Arthroplasty, Replacement, Hip↗
PubMed1986

Atraumatic removal of a well-fixed porous ingrowth hip prosthesis.

The authors describe their experience in the removal of a firmly fixed porous coated femoral component of a bipolar hip prosthesis in a 36-year-old man on a methadone maintenance program. The uncemented prosthesis had been implanted for 15 months when the patient complained of hip pain. A methicillin-resistant Staphylococcus aureus infection was found in the hip joint. It was decided to remove the femoral component when the infection failed to respond to irrigation, debridement, and several weeks of intravenous antibiotic therapy and because the patient developed early signs of impending renal compromise and a deterioration of his general nutritional status. The technique for separating and removing the well-fixed porous ingrowth component from its intramedullary environment without damaging the cortical tube of the proximal femur is described.

Adult↗
PubMed1982

Concept and material properties of a cementless hip prosthesis system with Al2O3 ceramic ball heads and wrought Ti-6Al-4V stems.

A cementless total hip system of modular design is presented. The design of the stem provides for a firm seating on the cortical bone over a large area. Therefore primarily stable fixation is accomplished. The stem in seven different sizes is made of hot forged Ti-6Al-4V Protasul-64 WF alloy of high corrosion fatigue strength. The Biolox ceramic ball with three different neck lengths is connected to the high strength stem by means of a special selflocking conical spigot with a structured surface. The ceramic ball is combined with a polyethylene screw socket in four different sizes, designed by Endler and anchored in the acetabulum without acrylic cement. This hip prosthesis system has proved itself in clinical application since 1979.

Alloys↗
PubMed1986

Six-year results with a microporous-coated metal hip prosthesis.

In an attempt to obtain bone ingrowth into a microporous-coated metal implant, a hip prosthesis with a pore width of approximately 50 microns was used in 34 cases. Implants revised up to six years following surgery have all shown fibrous tissue ingrowth only. Neither sinkage nor osteoporosis was observed. Revision was made difficult by the presence of a collar obstructing access to the proximal junction between the implant and bone.

Aged↗
PubMed1991

Comparison of the stability of press-fit hip prosthesis femoral stems using a synthetic model femur.

The motion of three different press-fit hip prosthesis femoral components was compared with that of a cemented stem and an Austin Moore noncemented hemiarthroplasty. Synthetic composite femurs were used as an experimental model to reduce the variations in shape and quality typical among cadaver femurs. Motion was measured under axial and rotational loading approximating a walking load. On the initial application of load, axial subsidence was as much as several millimeters for the noncemented stems. Considerable tightening occurred during the 5,000 walking cycles, such that the motion of the noncemented stems in some directions eventually was as small as that of the cemented stem, on the order of tens of microns.

Biomechanical Phenomena↗
PubMed1985

Focal lytic lesions associated with femoral stem loosening in total hip prosthesis.

Focal lytic lesions may occur in the proximal femur associated with loosening of the femoral component of a total hip prosthesis. During long-term follow-up of 62 patients with total hip prostheses, five such lesions developed. Histologically the lesions appear to be a histiocytic response to fragmented methylmethacrylate. Radiographically the lesions may suggest infection or neoplasm. Pathologic fracture may occur through large lesions. Experience in one case suggests that thorough removal of the tissue at the time of revision may be necessary to prevent recurrence. The recent reports of several malignant neoplasms developing in association with the femoral components of total hip replacements makes recognition of these benign focal lytic lesions even more important.

Aged↗
PubMed2001

[The use of Bicontact hip prosthesis in treatment of coxarthrosis].

The issue of a stabile, long lasting bone-implant interface is still very valid. One of the new models of uncemented hip prosthesis is the Bicontact prosthesis made by Aesculap. This four-part endoprosthesis offers two types of cups: threaded München type and spherical Plasmacup type. The prosthesis stem is a wedged type stem, porous in the proximal type. The aim of this paper was to evaluate the value of Bicontact prosthesis in treatment of coxarthrosis. Our material consisted of 69 patients (38 female and 31 male) with 72 operated hips. Average age of the patients was 50.8 years. The mean follow-up was 24.5 months. Clinical and radiological evaluation according to Merle d'Aubine-Postel classification with Charnley's modification yielded 88% very good and good results. In 11 hips a similar complication was noted--fracture of the femur during final hammering of the prosthesis stem into the medullary canal. This was immediately repaired by circular wire fixation without any influence on the final result. This complication was observed during the first procedures. The learning curve of surgical technique allowed us to avoid this complication during subsequent procedures. We concluded that type of hip prosthesis was is very useful in in treatment of coxarthrosis.

Adult↗
PubMed1997

Fretting wear in a modular neck hip prosthesis.

In vitro cyclic load fretting tests were conducted on a prototype of a cementless, modular neck, hip prosthesis. The study had three major objectives: to determine the amount of fretted material in the tapered-neck joint under various load cycle amplitudes, to determine the fretting damage evolution, and to determine the effect of different-sized stem bodies on the production of debris. All the tests produced some fretting microdamage on the tapered surface although the extent was quite different among test groups. The amount of abraded material increased almost linearly with the applied load magnitude but not with the number of load cycles. The amount of weight loss was higher in the large stem bodies than in the small ones. Weight loss ranged from 0.28 +/- 0.10 mg for small stem bodies loaded 5.5 million times up to 2300N to 2.54 +/- 0.53 mg for large stem bodies located 20 million times up to 3300N. Considering the large-size stem results, and assuming one million load cycles between 300N and 3300N to be the average yearly load history, the modular neck tapered joint would produce 0.6 mg/year of metal debris. The clinical impact of this observation is unknown; however, some of the literature on the presence of metal in patient tissues and fluids supports the hypothesis that a normal and stable prosthesis is likely to produce less than 10 mg/year of metal debris. Thus, a further production of 0.6 mg/year due to the modular neck should not have any significant effect.

Alloys↗
PubMed1992

Assessment of the deformation of the Bateman bipolar hip prosthesis inner bearing due to moisture absorption and creep.

The mechanism of inner bearing stiffness of bipolar hip prostheses has been investigated. The Ultra-high Molecular Weight Polyethylene (UHMWPE) component of the Bateman bipolar hip prosthesis has been subjected to a series of static and dynamic tests to assess water absorption and creep. Although deformation of the UHMWPE occurred, this did not produce an increased resistance to movement in the inner bearing.

Biomechanical Phenomena↗
PubMed1991

Retrieval analysis of a hydroxyapatite-coated hip prosthesis.

A 61-year-old woman fitted with a hydroxyapatite (HA)-coated macrotexture all-purpose hip prosthesis died three weeks after implantation. The retrieved femoral and acetabular components were examined using contact roentgenograms, the back-scattered mode of the scanning electron microscope, and light microscopy. Newly formed bone was observed in the marrow spaces and along the morselized autograft bone chips, which had been surgically placed in the medullary canal at the time of implantation. New bone was observed along 10% of the HA surface of the femoral component and 20% of the acetabular component. Some bone was also observed connecting the surrounding bone chips to the HA coating. Light microscopy showed the presence of osteoid on 20% of the femoral component and on 40% of the acetabular component. HA coating on total hip prostheses appears to enhance early skeletal attachment, which may be attributed to the osteoconductive properties of the composite.

Durapatite↗
PubMed1996

Stable partial debonding of the cement interfaces indicated by a finite element model of a total hip prosthesis.

A simplified three-dimensional finite element model of the femoral component of a cemented total hip prosthesis was used to investigate whether partial debonding at the stem-cement or bone-cement interfaces propagates in a stable or unstable manner, and to assess the resultant variation of the stresses within the cement layer. The likelihood of unstable debonding under tensile failure mode was assessed both by a conventional monotonic strength criterion and by a fracture mechanics approach that took into account debonding due to fatigue loading. The model predicted that partial debonding at the cement interfaces would be stable and would not precipitate complete debonding. Among the various bonding conditions that were investigated, the maximum tensile stress within the cement layer was least with a small amount of debonding rather than with complete bonding. These results were consistent with clinical observations of nonprogressive or slowly progressive separation at cement interfaces in cemented femoral components that were otherwise well functioning and asymptomatic.

Biomechanical Phenomena↗
PubMedDate not supplied

Biomechanical considerations of multiple-component hip prostheses. Analysis of three failures of the Lippman transfixation hip prosthesis.

Three cases are presented and analyzed in which a Lippman Transfixion Hip Prosthesis had to be replaced because of the discomfort of the patient. In each case, there was evidence of wear between the head of the prosthesis and the flange. The different wear patterns indicated problems which exist in the alignment of component parts of the prosthesis. In each case there was low grade sepsis to which the debris may have contributed. Because of phagocytosis, amount of debris accumulation was difficult to evaluate. The factors which appear to have contributed to the amount of debris accumulation were: the length of time the prosthesis had been used; the degree of alignment and amount of debris which may be formed and is phagocytized; the degree of manufacturing control. The design of this prosthesis incorporated mechanical problems which are generally undesirable because of: the eventual deformation of the end of the pivot rod or hole in the head of the prosthesis: progressive loosening of the movement due to this and inherent malalignment; the difficulty in fabrication, assembly and installation of the prosthesis because of the multiplicity of parts; the difficulty in maintaining adequate control of surface finishes.

Arthroplasty↗
PubMed1999

[Uretero-acetabular fistula after removal of a septic total hip prosthesis].

The authors report a case of an uretero-acetabular fistula after a Girdlestone procedure. The reason of ablation was an infected hip prosthesis. The urinary fistula was treated with an uretero-ileoplasty and hip infection with a two stages procedure. There was no recurrence of infection at two years follow-up. Different causes of this urinary complication are discussed.

Acetabulum↗
PubMed1990

[Total hip prosthesis in patients less than 50 years of age. Value of ceramic materials].

87 consecutive cases of sealed total hip prosthesis with an alumina/alumina friction couple, placed in 76 patients less than 50 years old, have been studied. The surveillance period ranged between 2 and 13 years for 74 of them. 51 have been followed over more than 5 years, 10 have been lost out of sight and 3 died. 5 failures are to be deplored, one by fracture of a 22 mm ceramic head, the normal size in this series being 32 mm; the 4 others occurred after 6, 6, 10 and 11 years and are the consequence of a cotyloid loosening. Compared to the other series in literature concerning young patients and therefore those considered to be "at risk", the results obtained are better, especially if the high number of cases re-operated upon in this series (18 prosthesis exchanges out of 87) is taken into account. The actuarial method of Kaplan Meier gives a probability of 94% of keeping the prosthesis for 8 years. It is undoubtedly the quality of the design of the titanium femoral stem and especially the small amount of erosion scraps produced by the alumina/alumina couple which explain this result. The hip replacement must however remain an exceptional indication in a young subject.

Adult↗
PubMed1986

[Study of a painful total hip prosthesis].

The authors propose a simple routine survey to be performed in the case of a painful total hip prosthesis which is generally able to define the diagnosis and the prognosis. X-ray films are more valuable by their repetition than by their simple analysis. Certain minor signs can help predict or detect loosening of the prosthesis or other complications, but in the great majority of cases, radiology alone is not sufficient to make the diagnosis, as the films are only able to show clear spaces around the prosthesis, without being able to definitely confirm the aetiopathogenic significance of this sign. In these cases, when the decision has not been taken to re-operate, more sophisticated investigations are required (scintigraphy, dynamic tests, arthrography), although they must be used with caution as very often the clinical findings will have the last word.

Bacteriological Techniques↗
PubMed1995

Cancellous bone stresses surrounding the femoral component of a hip prosthesis: an elastic-plastic finite element analysis.

The cancellous bone stresses surrounding the femoral component of total hip replacement were investigated using the finite element method. Four versions of a certain femoral hip prosthesis (the Freeman, Corin Medical), cemented, HA coated, press-fit, and press-fit with ridges were analysed. Each model was subjected to two separate load cases with the cancellous bone modelled as an elastic perfectly plastic material. The effect of bone quality was investigated by varying the cancellous bone stiffness. The resulting cancellous bone stress distributions were compared to that of the intact femur. The results were also compared to clinical subsidence data (published elsewhere) for the Freeman femoral prosthesis to determine if the initial cancellous bone stress distribution could be used to predict the migration of the various versions of this prosthesis. The results showed that the press-fit designs of prosthesis generated substantially higher cancellous bone stresses than the cemented and HA coated designs, and that these stresses were up to 6.5 times higher than found in the intact femur. For all forms of fixation the cancellous bone stress distribution was found to be insensitive to changes in the trabecular bone stiffness: thus poor quality cancellous bone is more likely to promote 'plastic' deformation, and therefore subsidence of the prosthesis. Comparison with the clinical migration data showed a good correlation and revealed that it may be possible to use the calculated initial cancellous bone stresses to predict the migration of the implant, and hence the probability of early and mid-term aseptic loosening.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomechanical Phenomena↗
PubMed1998

Composite hip prosthesis design. II. Simulation.

An investigation was performed to study the mechanical performance of fiber-reinforced composite hip prostheses. In Part I of the study, a three-dimensional finite element code was developed for analyzing a composite hip prosthesis in a femur. The material properties of the composite were treated as anisotropic and inhomogeneous while the properties of the femoral bone were treated as anisotropic and homogeneous. All the materials were assumed to behave linear-elastically. Thermoplastic graphite/PEEK material was selected for the study. No slippage was assumed at the interface between the implant and the surrounding femoral bone. In Part II, numerical simulations were performed using the code to study the performance of a composite prosthesis in the femur. The stress/strain distributions, micromotions, and strain energy density of the surrounding femoral bone were evaluated and found to be related to initial fixation and long-term stability of the prosthesis in the femur. Numerous fiber orientations were studied, and the results of the calculations were compared with those generated from a prosthesis made of cobalt chrome and Ti-6Al-4V titanium alloys. Based on the analysis, it was shown that compared to conventional metallic implants more favorable stresses and deformations could be generated in the femur using composite implants. In addition, by changing fiber orientations according to femoral loads, a composite implant could be designed specifically for the left or the right femur.

Computer Simulation↗