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At least 145 records · Page 8Linked to original sources
PubMed1990

New design of hip prosthesis using carbon fibre reinforced composite.

We present a new design for a hip prosthesis using polyethylene-hydroxyapatite, a composite material with layered stiffness and good bone compatibility. In order to overcome the low stiffness of the matrix, carbon fibre reinforcement is suggested. This new collarless prosthesis was designed to give maximum stiffness at the core and lower stiffness at the bone-implant interface. For this design a 2D finite element analysis was undertaken; its results were compared with those for a titanium alloy prosthesis. The effect of the variation in the collar stiffness was also analysed.

Carbon↗
PubMed2004

Biomechanical analysis and quantitative analysis of bone scintigraphy on thrust plate hip prosthesis.

INTRODUCTION: To study the load distribution of the thrust plate hip prosthesis (TPP, Sulzer Medica, Baar, Switzerland) on femoral bone, a TPP insertion group and intramedullary cemented stem insertion group were prepared with the use of embalmed femoral anatomic specimens, and strain on the femoral bone induced by loading was measured. MATERIALS AND METHODS: Bone scintigraphy was performed in 26 joints which underwent total hip arthroplasty with the use of TPP, to enable quantitative evaluation of postoperative remodeling of the bone. RESULTS: In the TPP insertion group, the strain was almost equivalent to that in the untreated femoral control group. On the other hand, compared with the control group and TPP insertion group, strain in the proximal portion of the femoral bone (medial side of the femoral neck) was significantly smaller in the cemented stem group (control group versus cemented stem insertion group, p=0.0062; cemented stem insertion group versus TPP 130 degrees insertion group, p=0.0005; cemented stem insertion group versus TPP 140 degrees insertion group, p=0.0031). Bone scintigrams revealed decreased uptake at 12 weeks after operation compared with 6 weeks after operation, indicating that TPP allows earlier implant stabilization than the conventional stem. CONCLUSION: Compared with the conventional stem, TPP is a prosthesis that can perform physiological load transmission.

Aged↗
PubMed1999

Behavior of the femoral stem in the Bihapro hip prosthesis.

This study evaluated the hydroxyapatite-coated femoral stem of the Bihapro hip prosthesis (Biomet Ltd, Bridgend, United Kingdom) using radiography, TC-99 scintigraphy, and bone densitometry. Thirty stems with >2 years of follow-up (mean: 31 months) were evaluated. No loosening or changes in the position of the implant were seen, and the mean subsidence was 2.2 mm. Radiography revealed a densification in the metaphyseal zone with reconstruction of the trabecular lines in 21 cases, while in 22 patients, radiolucent lines in the distal area of the femoral component were observed. Scintigraphy showed a diaphyseal normo-captation in 19 cases and a hypercaptation <1.4 with a mean index of 1.1 in 10 patients. Metaphyseal hypercaptation >1.4 was seen in 24 patients. Bone densitometry revealed increased density in the metaphyseal zones in 29 patients with a periprosthetic/normal bone quotient of 1.4.

Bone Density↗
PubMed1996

A method for shape optimization of a hip prosthesis to maximize the fatigue life of the cement.

The long term success of total joint replacement can be limited by fatigue failure of the acrylic cement and the resulting disruption of the bone-cement interface. The incidence of such problems may be diminished by reduction of the fatigue notch factor in the cement, so that stress concentrations are avoided and the fatigue crack initiation time maximized. This study describes a method for numerical shape optimization whereby the finite element method is used to determine an optimal shape for the femoral stem of a hip prosthesis in order to minimize the fatigue notch factor in the cement layer and at interfaces with the bone and stem. A two-dimensional model of the proximal end of a femur fitted with a total hip prosthesis was used which was equivalent to a simplified three-dimensional axisymmetric model. Software was developed to calculate the fatigue notch factor in the cement along the cement/stem and cement/bone interfaces and in the proximal bone. The fatigue notch factor in the cement at the cement/stem interface was then minimized using the ANSYS finite element program while constraining the fatigue notch factor at the cement/bone interface at or below its initial level and maintaining levels of stress in the proximal bone to prevent stress shielding. The results were compared with those from other optimization studies.

Algorithms↗
PubMed1994

Photoelastic simulation of a cementless and of a hydroxyapatite coated total hip prosthesis.

Remodelling of bone, regularly observed after the implantation of a hydroxyapatite coated Furlong hip prosthesis, stimulated the authors to analyse the stress distribution and relative magnitude in photoelastic models, of 1. the upper half of an intact femur; 2. of a femur equipped with a prosthesis free of glue to simulate the implantation of a cementless non coated prosthesis; and 3. of a femur in which a prosthesis was glued to simulate the implantation of a hydroxyapatite coated prosthesis. The results match precisely the remodelling thus observed in the X-rays.

Biomechanical Phenomena↗
PubMed2001

Hydroxyapatite coated hip prosthesis followed up for 5 years.

We prospectively studied 250 patients with a proximal hydroxyapatite coated hip prosthesis. The follow-up period was 5 years. All components showed osseointegration except for one deep infection. The morphology of bone remodeling with either endosteal bone formation or periosteal bone formation was dependent on the way the stem filled the medullary canal. No linear or distal osteolysis around the stems was observed.

Adult↗
PubMed1990

[Hip prosthesis in the elderly].

Total hip replacement is often used in elderly patients. We found that the results are almost as good in the elderly as in younger patients. Mortality is higher in the older, but for other complications, there is no difference between older and younger patients.

Age Factors↗
PubMed1985

[Posterior and external transtrochanteric approaches for total hip prosthesis. Comparative study].

1100 total hip prostheses were inserted between 1977 and 1978. Among them, the authors have selected at random 150 cases operated on by the Austin Moore approach and 150 cases by trochanteric division. The pathology and the type of patient were the same in both groups. A study of the late results showed no difference between the two series. In each, there were two early infections and three late infections. The rate of post-operative dislocation was the same, two early and six late in the Moore approach group, and five early, and two late in the trochanteric division group. There were six sciatic involvements after the Moore approach but only three after trochanteric division, but in this last group there were complications relating to the trochanteric division itself. There were no statistical differences in a comparison of the numbers of re-interventions required. Both techniques appeared to be satisfactory. The Moore approach appeared to be better for the comfort of the patient and does not give any additional risk. Trochanteric osteotomy is indicated in particularly stiff hips, when the greater trochanter has to be displaced downwards or in cases of post-operative scarring.

Femur Head↗
PubMed1994

[Total hip prosthesis in young patients].

Total hip prostheses are functional for a shorter period of time in young patients than in elderly. This problem is essentially related to the production of wear debris consecutively to metal versus polyethylene friction. New materials, such as alumina, produce less debris and therefore have been used for more than fifteen years with acceptable results at ten years (> 90% of functional hips). Total hip prostheses are sometimes needed in young patients suffering of post traumatic lesions, severe osteonecrosis and early osteoarthritis. In these cases, the indication of the prostheses should be accurately discussed, since it gives very often excellent results in comparison to more conservative treatments.

Adult↗
PubMed1981

[Tuberculous infection of total hip prosthesis: report on two cases (author's transl)].

M. tuberculosis infection of a total hip prosthesis was observed in two patients. Clinical and bacteriological diagnostic features are described, as well as the two possible physiopathological mechanisms involved: activation of a chronic local lesion or blood dissemination. Combined medical and surgical treatment results in effective clinical and functional recovery.

Adult↗
PubMed1992

Arthroscopic removal of acrylic cement from unreduced hip prosthesis.

A case is reported in which entrapped polymethylmethacrylate following traumatic dislocation of a total hip replacement prevented complete reduction. A combined arthroscopic and fluoroscopic technique was used to remove the entrapped polymethylmethacrylate. Manipulation of the total hip prosthesis was done after removal of polymethylmethacrylate to minimize mechanical abrasion. This technique allows direct visual assessment of the articulating surfaces as well as the mechanical stability of the prosthesis. The morbidity related to the procedure is minimal and a short rehabilitation period is the major advantage.

Aged↗
PubMed1992

Thoracic disk herniation and recurrent dislocation of total hip prosthesis.

We have described a patient who had thoracic disk herniation, recurrent dislocation of a total hip prosthesis, and heterotopic ossification. The recurrent dislocation resulted from spasticity from a spinal lesion, but the treatment focused on technical solutions related to the hip. Evaluation for total hip arthroplasty should include careful neurologic examination. If recurrent dislocation occurs, spasticity from an occult lesion should be considered. Resection of calcified thoracic disks should be approached with caution.

Female↗
PubMed1998

Severe metallosis in an isoelastic hip prosthesis.

Severe black staining due to metallic wear debris has been reported in metal-on-metal hip prosthesis(3). This problem is not commonly seen because of the popular use of metal-on-polyethylene component and has not been previously reported with the use of isoelastic femoral prosthesis. We report a case of severe metallosis in an isoelastic prosthesis, four years after implantation.

Femoral Fractures↗
PubMed1994

[Elective total hip prosthesis management in patients over 80 years of age].

Ninety-five primary elective total hip prosthesis procedures were carried out in patients over 80 years of age (average 82.9 years). The results were studied retrospectively to determine the individual risk-advantage relationship and the general cost-advantage relationship taking the social aspects into consideration. Fractures and emergency procedures were excluded. Ninety-three percent of the patients had preexisting general illnesses. There were no local or general complications in the peri- and postoperative courses of 86% and 85%, respectively. The general complications included urological (6%), cardiovascular (5%) and abdominal (3%) problems. The only death (myocardial infarction) took place 4 weeks after the operation during the rehabilitation phase. The average hospital stay was 23.3 days; 20% of the patients were then able to return home, while 80% were sent to another institution for further care (geriatric department, rehabilitation), where the average stay was 36.7 days. The total inpatient treatment period was on average 52.3 days. At the time of the last follow-up, an average of 4.6 years postoperatively, 75% of the patients were alive with an average age of 87.4 years. Seventy-nine percent were still able to live alone and look after themselves; 81% were independent or only partially dependent (living in a retirement home). Ninety-three percent had no pain or only mild pain. If indicated, the operation risk factor for total hip prostheses in patients over 80 years is obviously low, and the results are good. This operation permits the patient to have many years free of pain, to remain independent, and to achieve a clearly higher quality of life. In this way one can also save on the high cost of many years of nursing care.

Activities of Daily Living↗
PubMed2000

Hippin: a semiautomatic computer program for selecting hip prosthesis femoral components.

This work illustrates a computer program designed to aid surgeons in selecting the hip prosthesis femoral component during the preoperation planning stage of hip replacement surgery. Starting from the processing of the patient's coxo-femoral region X-ray image, the program, called Hippin, interacts with the user to outline the femoral region, including the head and the inner contour of the proximal femur. It automatically examines all possible couplings with the patient's femur outlines from a database containing the outlines of the available prostheses created by digitizing the templates normally used in preoperation planning. The resulting images enable the surgeon to visually compare all the alternatives. In addition, the program provides numerical values for the distances between the physiological rotation and prosthesis centers, helping the surgeon in selecting from among the possibilities. The program has been validated by comparing the computer results with actual surgeon selections.

Automation↗