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Mid-term results in total hip arthroplasty with the basic noncemented hip prosthesis.

The Basic (IQL-Biomet, Valencia, Spain) hip prosthesis was used in 430 implant procedures, of which 417 had mean follow-up of 6 years. Radiographic follow-up was performed at 1, 3, 6, and 12 months postoperatively, and annually thereafter. The average Harris hip score improved from 35.7 preoperatively to 90.9 postoperatively. Clinical results after 2 years of follow-up showed 6% thigh pain, which decreased to 2% at 6 years. Radiographic evaluation demonstrated 22 cases of calcar resorption, 14% of which had distal pedestal formation. Heterotopic ossification was noted radiographically in 36%. These mid-term results obtained with the Basic prosthesis are similar to the findings of other series and warrant its use.

Adult↗

Shape optimal design of the stem of a cemented hip prosthesis to minimize stress concentration in the cement layer.

An optimal shape of the metal stem of a cemented total hip prosthesis minimizing stress concentration in the cement layer was searched for. A gradient projection method of numerical optimization and a finite element method of stress analysis were employed. A two-dimensional model of the femoral part of a total hip prosthesis was derived equivalent to a simplified three-dimensional axisymmetric model. The result of the stress analysis of the two-dimensional model compared favorably with that of the three-dimensional axisymmetric model. Using this two-dimensional model, an optimal shape of the stem, minimizing stress concentration in the cement layer, was obtained by a gradient projection method and the shape was checked again by the three-dimensional finite element analysis. The resulting optimal shape of the stem profile was in good agreement with conventional ones, except in the proximal region where a significant amount of stress reduction in the cement layer was achieved by tapering the stem to the limit that the stem still could withstand the increased stem stress.

Bone Cements↗

Wear of polyethylene in the total hip prosthesis.

Direct in vivo measurement of wear of total hip prostheses by radiography is not possible. However, improved in vitro approaches have been developed that agree with clinical observations in all salient points. Such measurements show that the wear of the polyethylene component depends crucially on the molecular weight distribution (and probably on other structural variables). Combined with clinical retrievals, there is evidence that relatively high wear may occur even in the absence of acrylic debris. Although sufficient knowledge exists to reduce wear of the total hip prosthesis to a negligible level, for the total knee replacement with higher contact stresses, presently, this is not the case.

Equipment Failure↗

[Comparison of the efficacy and tolerance of Kabi 2165 and standard heparin in the prevention of deep venous thrombosis in total hip prosthesis].

A series of 80 patients operated for total hip prosthesis under epidural anesthesia was randomly allocated to treatment with Kabi 2165 (n = 40): 2,500 U anti-Xa preoperatively and evening of operation and 2,500 U anti-Xa morning and evening daily up to the 9th or 10th day postoperatively, or standard heparin (n = 40): 3,750 U preoperatively and then 8 hourly, at a dose adjusted with thrombin time and cephalin + activator time, daily up to the 9th or 10th day. Phlebography was performed routinely on the 9th or 10th day. Venous thrombosis occurred in 7 patients (17.5%) in the Kabi 2165 group, including two high, potentially emboligenic, localizations (5%), and in 4 patients (10%) in the standard heparin group, including 2 potentially emboligenic clots (5%). The difference is not statistically significant (total number: p = 0.5; potentially emboligenic: p = 0.33). Pulmonary embolism did not occur. Overall tolerance, evaluated from hemoglobin and hematocrit values, intra- and post-operative bleeding and operation wound hematoma and at injection site was comparable in the two groups.

Aged↗

Radical radiation therapy for carcinoma of the prostate in patients with a single hip prosthesis: a technique analysis using dose-volume histograms.

Radiation therapy of the prostate patient is sometimes complicated by the presence of a hip prosthesis. Using dose-volume histogram (DVH) data, various techniques were assessed in terms of rectal and bladder sparing, as well as total dose to the femoral head and neck. An attempt was made to isolate a suitable technique in prosthesis patients that was comparable to the standard 4-field box technique in nonprosthesis cases. A 3-field coplanar technique is identified as equally efficacious in terms of rectal sparing, while avoiding the hip prosthesis. The importance of using dose-wall histograms for the rectum in plan ranking is discussed, as are the limitations of DVH data analyses without biological endpoints.

Dose-Response Relationship, Radiation↗

Bilateral gait patterns in subjects fitted with a total hip prosthesis.

OBJECTIVES: The purpose of this report was to determine whether the muscle powers and the mechanical energies developed during the push-off period of the gait cycle of patients having a total hip prosthesis were different from able-bodied subjects as well as the effect on the nonoperated limb. DESIGN: Case control study. SETTING: All patients where independent and functional. PATIENTS: Four patients participated in the study. The indication for surgery was degenerative arthritis of the hip. There was also an able-bodied group. INTERVENTION: A Harris-Galante total hip prosthesis was used to restore hip stability and function. The patients were all operated on by the same orthopedic surgeon and had the same type of total hip replacement. MAIN OUTCOME MEASURE: Gait analyses showed that not only the hips of the surgical group were affected but also the knees. RESULTS: Peak power did not show any significant difference except for a decrease in the frontal plane of the operated hip power absorption. The operated hip developed 35% and 48% less energy than that of the able-bodied group in the sagittal and frontal planes, respectively. The nonoperated hip was also affected and developed 35% more energy in the sagittal plane than the operated limb but 20% less than that of the able-bodied group. There was a reduction of 47% in the energies developed in the knees of the surgical patient group. CONCLUSION: These results confirmed the presence of some mechanical dysfunction in the nonoperated limb.

Aged↗

Massive wear of a steel ball head by ceramic fragments in the polyethylene acetabular cup after revision of a total hip prosthesis with fractured ceramic ball.

The purpose of this case study of severe metallosis is to draw the attention of orthopedic surgeons to extremely serious results of this kind in the event of the fracture of the ceramic ball in a total hip prosthesis. Eleven months after implantation of a KJF hip prosthesis with an aluminum oxide ceramic ball in combination with a polyethylene acetabular cup, fracture of the ceramic ball was observed. After examining the polyethylene cup during the revision operation, the operating orthopedic surgeon merely replaced the fractured ceramic ball with a metal ball head made of stainless steel. Twenty-five months after this procedure, radiography revealed massive wear of the steel ball head with resulting severe metallosis of the surrounding tissues. All prosthetic components therefore had to be removed. Careful examination of the removed prosthetic components clearly showed that sharp-edged ceramic particles originating from the fractured ceramic ball had become embedded in the bearing surface of the polyethylene cup. These tiny ceramic fragments, ranging from 0.05 to 2 mm, were too small to be seen by the operating surgeon's unaided eye. It is these extremely hard ceramic fragments that were responsible for the massive wear of the steel ball head, the hardness of which is approximately ten times less than that of aluminum oxide ceramic. The fracture of the ceramic ball further resulted in damage to the metal taper of the stemmed femoral component. In cases of this kind it is consequently absolutely essential to remove both the polyethylene cup and the ball head, and--if necessary--the femoral component as well.

Acetabulum↗

[Harris and Galante non-cemented total hip prosthesis. 1st results].

Amongst the various models of total hip prosthesis available on the market, the Harris and Galante non-cemented implant constitutes an attractive alternative. The authors report their preliminary experience on the basis of a limited series (77 hips) and a follow-up of 6 to 30 months. The hemispherical acetabular prosthesis, which is very easy to use, induces a local reaction in about 10% of cases. The femoral pivot, inserted by means of a very sophisticated apparatus, is more frequently responsible for local reactions (4 circumferential rings, 2 of which were asymptomatic, and 24 partial rings particularly in Gruen's zone 1). Although the preliminary results of this short series appear to be encouraging (59 operated patients out of 63 were scored as D5 - D6), a longer follow-up is nevertheless essential.

Acetabulum↗

[Recurrent dislocation of the hip prosthesis].

Recurrent dislocation of a hip prothesis is a severe complication. For the patient it is debilitating both physically and mentally. In most such cases one or more revision operations are necessary. Reintervention is more likely to be successful if the cause and the mechanism of luxation are understood. Recurrent hip dislocation is often seen after insertion of socalled tumor prostheses, after the "southern" approach and in the case of fracture treatment. One helpful and secure method seems to be the conversion of a non-linked prosthesis to a linked prosthesis. For elderly patients the simplest method seems to be cementing the head of a bipolar hip prosthesis.

Acetabulum↗

Ten-year survivorship of cemented ceramic-ceramic total hip prosthesis.

In the first 187 consecutive alumina-alumina combination hip arthroplasties performed from 1977 to 1979, both components were cemented with conventional techniques. At ten-year follow-up evaluation, 87 patients were reviewed or interviewed by telephone, 37 were dead, 39 were lost to follow-up evaluation, and 24 failures were reoperated on before the end of ten years. The major cause of failure was aseptic loosening of the acetabular component (15 failures). Fracture of the socket and of the femoral head occurred in five patients in this series. However, these complications were not seen with components manufactured after 1979. At the end of ten years, survivorship analysis depicted a 82.59% survival rate when reoperation was considered as failure and a 88.57% rate when reoperation for aseptic loosening was considered as failure. The femoral component had a 99.16% survival rate and the acetabular component had an 88.57% survival rate when reoperation for aseptic loosening was considered as failure. Age, appearance of a two- or three-zone demarcation at the intermediate follow-up evaluation, and outer diameter of the acetabular component were the major parameters influencing the results. Better results observed in the population younger than 50 years of age may be related to the small amount of wear debris produced by the alumina-alumina combination. This combination in hip prosthesis is secure, but should be implanted in young and active patients; the outer diameter of the acetabular component must be at least 50 mm. The major problem that remains is the socket's fixation. It could be improved by a design modification, by choosing another mode of fixation, or both.

Aluminum Oxide↗

Dynamic compression plate fixation for post-operative fractures around the tip of a hip prosthesis.

Post-operative fractures around the tip of the femoral component of a hip prosthesis are inherently unstable and have been reported to be associated with high nonunion rate if treated conservatively. A group of 27 of these fractures were treated with dynamic compression plates between 1994 and 2000. The fractures followed primary total hip arthroplasty in 10 cases, revision surgery in five cases and hemiarthroplasty in 12 cases. According to the Vancouver classification, there were 18 type B1, six type B2 and three type B3 fractures. The average age was 82 years. The average follow up was 35.7 months (range 12-72 months). Complications included one nonunion (B3) and three fixation failures (one B2 and two B3). Also, two cases became infected, one of these was managed conservatively, the other needed removal of plate and prosthesis. Twenty patients regained their pre-injury mobility. Dynamic compression plate fixation is sufficient for type B1 and some selected cases of type B2 fractures that occur around the tip of a hip prosthesis.

Aged↗

[Hip metallosis caused by wear of a TT-1 stem on a ceramic modular head hip prosthesis --case report].

The author presents a case of metal stem cone wear caused by a ceramic head. During revision hip arthroplasty procedure a new modular ceramic head was implanted in combination with a stable cemented TT-1 stem. 13 months after surgery the hip became symptomatic and 20 months after the procedure total loosening of the cup was observed. Wear of the stem cone was visible. During the next revision procedure all hip prosthesis elements were removed, soft tissue debridement was performed and a new cemented prosthesis was implanted. One year post-op the hip is pain free.

Ceramics↗

Modelling evaluation of the testing condition influence on the maximum stress induced in a hip prosthesis during ISO 7206 fatigue testing.

In vivo fatigue failure of hip prosthesis stems has been extensively reported in literature. The ISO 7206 international standard has been developed to assess the fatigue reliability of hip prostheses. It describes the fatigue testing apparatus and procedure and it is currently adopted by several testing laboratories throughout the world. In this work we evaluate the maximum stress in a titanium alloy commercial stem in different testing conditions, ranging within the standard specification, using the finite element method applied to a 3D model of the stem. The calculated maximum von Mises stress ranges from +4.5 to -1.5% (for different cement constraint levels) and from +6.7 to -6.8% (for different stem angular orientations) with respect to that calculated at the nominal testing conditions. The results suggest that the ISO 7206 testing specification will give experimental data of reasonable accuracy, with probably no more scatter than that found in typical specimen test results. This is particularly important in the case of components manufactured from materials showing a fatigue resistance highly sensitive to stress variations, such as the Ti6A14V alloy, for which a small increase of the maximum applied stress corresponds to a significant decrease of the statistical fatigue life.

Alloys↗

The bi-articular hip prosthesis for fractures of the femoral neck--a preliminary report.

The bi-articular hip prosthesis (BHP), based on an original design by Bateman, is a bi-polar hemi-arthroplasty which seeks to reduce acetabular wear. We have used this prosthesis to treat 101 elderly patients with displaced intra-capsular fractures of the neck of the femur. The results of the first two years experience with this prosthesis are encouraging. Post-operative hip pain was not significant and did not interfere with mobility. The use of the antero-lateral approach to the hip joint prevented dislocation of the prosthesis, in contra-distinction to reports of series in which the Southern approach was used.

Aged↗

The Christiansen hip prosthesis preliminary results.

The combined endo- and total hip prosthesis of Christiansen is described. In this prosthesis an articular connection, or trunnion bearing, is introduced between the head and stem components in order to reduce friction at the acetabular joint. The stem portions of both prostheses are identical. The endoprosthesis was inserted in 50 patients, who were followed-up during one year. The results were according to the classification of Love (Surg. Clin. N. Amer., 1963, 43, p. 1217): excellent in 60%, good in 22%, and poor in 18% of cases. In addition some results from other Norwegian hospitals were presented.

Femoral Neck Fractures↗

Mycotic aneurysm of the external iliac artery caused by migration of a total hip prosthesis.

A 77-year-old patient had a mycotic aneurysm of the left external iliac artery secondary to migration of a total hip prosthesis. Symptoms included pain, numbness, decreased hip motion, and a temperature of 38.5 degrees. The left leg was shortened, externally rotated, and swollen. There was anterior thigh hypoesthesia and quadriceps paralysis. A pulsatile mass in the lower left quadrant of the abdomen emitted a thrill and a loud bruit. A preoperative arteriogram facilitated diagnosis and planning of surgery. A transpubic femorofemoral bypass graft was used to reroute blood to the left lower limb, avoiding vascular reconstruction in the area of the aneurysm, a suspected site of infection. A false aneurysm was determined and was then isolated. The prosthesis was removed. During this operation, the acetabular component was found freely mobile within the false aneurysm. Cultures of the removed vascular tissue grew Staphylococcus epidermidis. An arteriogram should be obtained prior to operation for any medial intrapelvic displacement of a total hip prosthesis to diagnose the extent of vascular involvement. Physical examination may not reveal the aneurysm, but signs of neuropathy or venous thrombosis may suggest this diagnosis.

Acetabulum↗