Advances in prevention of venous thromboembolic disease after elective hip surgery.
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Anticoagulants↗
Biomedical subjects
W H Harris
Publications and source records attributed to W H Harris.
Porosity of various preparations of acrylic bone cements.
The total porosity and mean pore sizes of various bone cement preparations were measured using image analysis. The porosity in different commercial bone cements varied from 5% to 16% when these cements were prepared in the usual fashion. Centrifugation for 30 seconds resulted in a substantial reduction in the overall porosity of Simplex P, AKZ, Zimmer Regular, and CMW bone cements by reducing both the mean pore size and the number of pores per unit area. In contrast, the porosity of LVC, Palacos R, and Palacos R with gentamicin bone cements was not significantly decreased by centrifugation. Chilling the monomer before mixing resulted in higher porosity of both the centrifuged and uncentrifuged Simplex P, Zimmer Regular, and CMW bone cements. Simplex P mixed with chilled monomer and centrifuged for 120 seconds has one of the lowest porosities of the various cements, while retaining good handling characteristics and excellent fatigue strength.
Acrylic Resins↗
A double-blind study on the effects of a capacitively coupled electrical field on bone ingrowth into porous-surfaced canine total hip prostheses.
The effect of a capacitively coupled electrical field on bone ingrowth into titanium fiber mesh porous-surfaced canine total hip arthroplasties (THAs) was investigated in a double-blind experiment. The electrical field was induced by an external source delivering a 60-kHz 5-6-V peak-to-peak sinusoid voltage through skin electrodes. No significant increase in the ingrowth of bone into the porous coating occurred at the end of six weeks of electrical stimulation. The amount of bone that grew into the porous surface, the areal density of bone within the available pore space, and the extent of the prosthesis surface area with bone ingrowth or apposition were not significantly different in the control and stimulated groups. This particular form of electrical stimulation does not improve bone ingrowth into porous-surfaced canine THAs by six weeks.
Animals↗
Comparison of a hybrid with an uncemented total hip replacement. A retrospective matched-pair study.
The efficacy of a type of uncemented total hip replacement was compared with that of a hybrid total hip replacement in which an uncemented acetabular and a cemented femoral component were used. Twenty-five patients who had had a hybrid total hip replacement were matched, by age, weight, sex, and diagnosis, with twenty-five patients who had had an uncemented total hip replacement. All of the operations were done by one surgeon, who used the same operative approach and the same regimen of postoperative rehabilitation. All of the patients were followed for at least two years. The mean postoperative hip score was 96 points for the hybrid group and 84 points for the cementless group (p less than 0.02). Twenty-four (96 per cent) of the patients who had a hybrid prosthesis reported no or only slight pain postoperatively. In the uncemented group, of the six patients (24 per cent) who reported mild to severe pain, five had pain in the thigh, a limp occurred more frequently, five femoral components had migrated, and four hips needed reoperation. The results with the hybrid replacement that had a cemented femoral component were superior to those with the uncemented femoral component over the relatively brief period for which these patients were followed.
Aged↗
Failure of acetabular autogenous grafts in total hip arthroplasty. Increasing incidence: a follow-up note.
We reported previously on the application of an autogenous femoral-head graft to the acetabulum during total hip arthroplasty for compensation of marked osseous deficiency in patients who had arthritis secondary to severe congenital dysplasia or dislocation of the hip. An average of seven years postoperatively, the graft seemed to have been a successful adjunct to the arthroplasty. Five years later, to assess our long-term results, we reviewed the findings in the same forty-six hips (thirty-seven patients) that we had studied previously. An average of 11.8 years after the total replacement and use of the autogenous femoral-head graft, nine hips (20 per cent) needed a second operation because the acetabular fixation had failed. Two had had a resection arthroplasty and seven, a complex revision. In one additional hip, a resection arthroplasty was done for infection that had developed after operative reattachment of the greater trochanter. In twelve of the remaining thirty-six hips, there was definite radiographic evidence of acetabular loosening. Thus, the total incidence of loosening of the acetabular component was 46 per cent (twenty-one hips). The average time from the index operation to the first definite radiographic evidence that the fixation had failed was 6.4 years (range, 2.9 to 12.7 years). While we recognize that application of a bulk autogenous graft to the acetabulum is useful when the acetabular bone stock is extremely deficient, we no longer recommend the use of bulk corticocancellous autogenous grafts in other situations.
Acetabulum↗
Clinical and radiographic evaluation of total hip replacement. A standard system of terminology for reporting results.
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Activities of Daily Living↗
Optimization and comparison of three vacuum mixing systems for porosity reduction of Simplex P cement.
Simplex P bone cement was prepared in three commercially available vacuum mixing systems, the Enhancement Mixer, the Mixevac II High Vacuum System, and the Mitab Vacuum System, to determine the improvement in fatigue strength associated with porosity reduction of the cement in all three systems. The results of the fatigue tests of vacuum-mixed Simplex P were also compared to the fatigue strength of Simplex P prepared by centrifugation of the cement immediately after mixing. Vacuum mixing one pack of Simplex P per syringe in all three systems was not effective in complete removal of all the large voids from the cement. Fatigue failure occurred very early in those specimens containing the large voids. There was no significant difference in fatigue life between one pack of cement per syringe mixed under vacuum in the three systems and the control cement (no vacuum, uncentrifuged). Vacuum mixing two packs of cement per syringe was more effective than one pack per syringe, and all three systems significantly increased the cycles to failure of Simplex P over the control cement. However, the Enhancement and Mitab vacuum mixing systems still produced some very weak specimens in fatigue. Two packs of cement per syringe prepared in the Mixevac II vacuum mixing system were significantly stronger in fatigue than two packs mixed in either the Enhancement or Mitab vacuum system. The Mixevac II vacuum mixing system was the most effective technique of the three vacuum mixing systems tested. Centrifugation of one or two packs of Simplex P per syringe produced a more uniform cement that was free of large voids and thus eliminated the very weak specimens.(ABSTRACT TRUNCATED AT 250 WORDS)
Bone Cements↗
Endosteal erosion in association with stable uncemented femoral components.
Sixteen cases of patients who had focal femoral osteolysis after total hip replacement without cement were identified. Fourteen of them were included in a retrospective review of 474 consecutive total hip replacements without cement in 441 patients who had been followed for at least two years. The criteria for inclusion in the study were focal osteolysis with a femoral component that appeared stable radiographically, and no subsidence or change of position of the implant. All but two patients were men and were quite active. The average age was forty-seven years (range, twenty to sixty-five years). Fourteen of the sixteen patients had an excellent clinical result (a Harris hip score of 90 points or more). In two patients, the hip replacement was revised and, in a third, a biopsy was done. In all three patients, the implant was found to be firmly fixed to the femur. In the two hips that were revised, extensive ingrowth of bone was demonstrated histologically, there was no evidence of infection, and a well defined fibrous membrane was found around the smooth portion of the stem. The histological specimens from these two hips contained focal aggregates of macrophages with particulate polyethylene and metallic debris. In the biopsy material from the hip that was not revised, a fine fibrous membrane lined a cystic cavity. Although the membrane contained an occasional macrophage, no foreign material was identified. Trabecular microfracture and osteoclastic resorption of bone were seen next to the fibrous lining. With one exception, osteolysis was not identified less than two years postoperatively. In most patients, osteolysis appeared after three years. This study showed that femoral osteolysis can occur around uncemented components.
Adult↗
Histomorphological studies of the long-term skeletal responses to well fixed cemented femoral components.
Thirteen femora that were obtained at autopsy from patients in whom a cemented total hip replacement had been implanted from forty months to 17.5 years earlier were evaluated radiographically and morphologically. All of the patients had been functioning well, and only one of the prostheses showed radiographic evidence of loosening. Serial sections of the proximal portion of the femur that enclosed the femoral component of the prosthesis showed that the host bone was intimately and directly apposed to the cement, and fibrous tissue intervened only rarely. The bone-remodeling processes had created a dense shell of substantial new bone around the cement-mantle that resembled a new cortex, attached to the outer cortex by new trabecular struts. Evidence of ingrowth of bone from this dense shell of bone into the undulating surface of the cement was found in many areas. In the adjacent femoral cortex, there was substantial osteoporosis and cortical thinning. The cement-bone interface was intact and excellent throughout, despite the presence of fractures within the cement-mantle and de-bonding at the cement-prosthesis interface in some specimens. The cemented femoral components were well tolerated by the skeleton over a long period of use, and fibrous tissue had rarely formed at the femoral cement-bone interface of these well fixed and clinically successful prostheses. The cement-mantle was well supported by extensive medullary bone-remodeling and formation of a dense shell of new bone. The internal bone-remodeling helped to maintain the cemented femoral components over time and did not cause loosening of the prosthesis.
Adult↗
Influence of antibiotic impregnation on the fatigue life of Simplex P and Palacos R acrylic bone cements, with and without centrifugation.
The fatigue properties of Simplex P and Palacos R bone cements were compared to their antibiotic impregnated counterparts AKZ* and Palacos R with gentamycin. The effect of porosity reduction by centrifugation of all four cement types was also assessed. Fifteen specimens of each cement type were prepared according to manufacturer's instructions and 15 additional specimens of each cement type were prepared by mixing the powder with chilled monomer (0 degrees C) and then centrifuging the cement immediately after mixing. Fifteen fully reversed tension-compression fatigue tests were performed at 15 MPa in stress control for each cement preparation in vitro while simulating the in vivo state (37 degrees C and 100% humidity). The number of cycles to failure were recorded. There was no significant difference in the fatigue life of Palacos R and Simplex P when both cements were prepared in the standard fashion. The addition of 1/2 g of gentamycin to Palacos R did not significantly alter its fatigue properties. The addition of 0.5 g of erythromycin and 0.24 g of colistin did not decrease the fatigue life of Simplex P. Centrifugation significantly improved the fatigue properties of Simplex P and AKZ. The fatigue lives of Palacos R and Palacos R with gentamycin were not improved by centrifugation. The fatigue life of centrifuged Simplex P was significantly greater than the fatigue life of Palacos R and of Palacos R with gentamycin, whether the Palacos R based cements were centrifuged or not.
Biocompatible Materials↗
Comparison and optimization of three centrifugation systems for reducing porosity of Simplex P bone cement.
Simplex P bone cement was spun for 30, 60, and 120 seconds in three different centrifugation systems (I.E.C. HN-S II, I.E.C. clinical, and Johnson & Johnson) to determine whether differences among the three systems also produce differences in the improvement of the fatigue strength of the cement. The fatigue properties of the cement after centrifugation were also assessed when it was mixed with monomer that had been chilled to 0 degrees C. There were important and statistically significant differences in the fatigue life of Simplex P spun for the same duration in the different centrifuges. Simplex P prepared as recommended by the manufacturer had an average fatigue life of 15,143 cycles in the test system used. Optimum centrifugation among the techniques studied increased the fatigue life nearly fivefold, to the range of 71,000 cycles. Taking into account both the fatigue strength and the viscosity of the cement, the optimum centrifugation system for improving the fatigue life of Simplex P bone cement is the Miller cartridge containing two packs of cement spun in the IEC-HN-S II centrifuge. The authors recommend 30 seconds of centrifugation if the monomer is not chilled prior to mixing and 60 seconds if the monomer is chilled.
Bone Cements↗
Uncoupling protein and its mRNA in brown adipose tissue of newborn rabbits.
Guanosine diphosphate binding to the uncoupling protein of isolated mitochondria of brown adipose tissue in newborn rabbits was measured as an index of thermogenic activity. The binding was 0.281 +/- 0.022 nmol GDP/mg mitochondrial protein at 1 day of age, 0.214 +/- 0.017 at 3 days, 0.428 +/- 0.038 at 5 days, and 0.208 +/- 0.016 at 7 days. The increase in binding between 3 and 7 days of age suggests that the brown fat has an increased thermogenic capacity at that age. In addition, the potential for synthesis of the uncoupling protein was investigated in 1- to 5-day-old newborn rabbits by probing the total cellular ribonucleic acid for the messenger that codes for uncoupling protein. The amount of uncoupling protein messenger was highest at 1 day of age and declined at least until 5 days of age. Because the amount of uncoupling protein messenger decreased as the GDP binding increased, the results suggest that either the initially translated uncoupling protein was unmasked at about 5 days of age or there was a delay in the incorporation of uncoupling protein into the mitochondrial inner membrane, or both.
Adipose Tissue, Brown↗
The effect of centrifuging bone cement.
We have tested the porosity and fatigue life of five commonly used bone cements: Simplex P, LVC, Zimmer regular, CMW and Palacos R. Tests were conducted with and without centrifugation and with the monomer at room temperature and, except for LVC, at 0 degrees C. We found that the fatigue life of different specimens varied by a factor of nearly 100. It did not depend on porosity alone, but was more influenced by the basic composition of the cement. Simplex P when mixed with monomer at 0 degrees C and centrifuged for 60 seconds had the highest fatigue life and was still sufficiently liquid to use easily.
Bone Cements↗
Clinical evaluation and cost effectiveness of preoperative laboratory assessment on patients undergoing total hip arthroplasty.
By examining the records of 101 admissions (86 patients) undergoing total hip replacement for osteoarthritis, we studied the impact of 24 preoperative laboratory assessments on the postoperative course. Four patients had their procedures postponed or canceled because of laboratory abnormalities; three of these patients had abnormal urinalyses and one had abnormal liver function tests. No other patients had alterations in their perioperative course as a result of the tests. No subsequent postoperative complications were attributable to either an abnormal or deficient preoperative assessment. Two patients with postoperative hepatitis had normal preoperative liver function studies. One patient had a postoperative bleeding episode but had had normal preoperative PT and PTT values. The economic implications are discussed in a cost-effectiveness model. On the basis of these results, we recommend that only a minimal set of preoperative laboratory tests be added to the detailed medical history and physical examination in otherwise healthy patients about to undergo total hip replacement surgery.
Clinical Laboratory Techniques↗
Biomechanical and histologic investigation of cemented total hip arthroplasties. A study of autopsy-retrieved femurs after in vivo cycling.
Eleven whole anatomic specimens of the femur were retrieved at autopsy from patients who previously had cemented total hip arthroplasty. Implant duration ranged from 0.5 to 210 months. Clinically and roentgenographically the implants were stable. A detailed biomechanical analysis evaluated bone strains and implant stability in both the single-limb stance and stair-climbing positions using a 100-pound spinal load. The stability offered by cement in these well-fixed prostheses was remarkable, with the maximum axial micromotion being 40 mu. This is a reflection of intimate osseointegration at the bone-cement interface with only rare intervening fibrous tissue. The strain gauge and photoelastic strain-coating studies revealed that marked stress shielding in the proximal medial femoral cortex persists long after a cemented femoral component is inserted. Even 17 years after surgery, the strain in the calcar region did not normalize.
Adult↗
Hybrid total hip arthroplasty.
One hundred twenty-six primary total hip arthroplasties composed of a hybrid cemented femoral component and a cementless acetabular component were followed for a minimum of two years (mean, 42 months). The average patient age was 63 years. The most common diagnosis was osteoarthritis (85 hips), although 13 of the cases were severe or total congenital dislocations. Overall, the results were excellent. The mean Harris hip score was 93. Postoperative pain was rated as none or slight in 94% of the cases. No patient had moderate or severe pain. No femoral or acetabular components were revised. Roentgenographically no femoral component was definitely or probably loose. One acetabular reconstruction component had migrated. The authors conclude that the selective use of cemented and cementless fixation by anatomic site in this hybrid form of hip arthroplasty provided excellent results for five and one-half years.
Acetabulum↗
Bone ingrowth into porous coated canine total hip replacements. Quantification by backscattered scanning electron microscopy and image analysis.
Bone ingrowth into titanium fiber mesh porous-surfaced canine total hip replacement prostheses was evaluated and quantified using a computer assisted image analysis system attached to a scanning electron microscope equipped with a back scattered electron detector. Excellent contrast between the bone, the porous metal and the soft tissues resulted in the backscatter mode, allowing easy differentiation of these components in real time by the image analysis based on gray scales. By three weeks the mean (+/- standard deviation) amount of bone ingrowth expressed as a percentage of porous layer measured 7.2% (+/- 1.5%) for the acetabular components, and 3.9% (+/- 1.7%) for the femoral components. At six weeks the amount of bone ingrowth increased to 10.5% (+/- 1.3%) for the acetabular components and 8.5% (+/- 1.4%) for the femoral components. Cementless prosthetic fixation using porous surfaced prostheses holds great promise in joint replacement surgery, and the ability to quantitate the amount of bone ingrowth will permit the evaluation of the efficacy of various techniques to improve bone ingrowth.
Animals↗
A preliminary report of the use of a cementless acetabular component with a cemented femoral component.
A clinical and roentgenographic study was done on 52 primary total hip arthroplasties (THAs) in which all patients were treated with hip reconstruction with a combination of a cementless, porous-coated acetabular component and a cemented femoral component. The operations were performed between November 1982 and May 1984, and the patients were followed for an average of 31 months (range, 24-40 months). The average age of the patients (55 years) was younger than in many THA series. At the last follow-up assessment, 50 hips were classified as good or excellent, one as fair, and one as a poor result. No total hip component required revision. No acetabular components had migrated as judged by conventional roentgenographic examination, and only one hip had progressive radiolucencies around the acetabular component. No femoral component was rated definitely loose or probably loose, and only one was rated possibly loose. If long-term follow-up study confirms these preliminary results, the combination of a cemented femoral component with a cementless socket may prove to be of value for selected patients requiring THA.
Acetabulum↗