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Biomedical subjects

H Malchau

Publications and source records attributed to H Malchau.

At least 37 records · Page 2Linked to original sources
PubMed1999

Porous cups with and without hydroxylapatite-tricalcium phosphate coating: 23 matched pairs evaluated with radiostereometry.

Migration, wear, and presence of radiolucencies were studied in 23 matched pairs of patients operated with porous-coated acetabular cups with additional screw fixation. All implants had the same type of titanium fiber mesh. In each pair, one of the cups was plasma-sprayed with a coating consisting of 70% hydroxylapatite (HA) and 30% tricalcium phosphate (TCP). Radiostereometric analysis up to 2 years after the operation revealed smaller rotations around the horizontal axis in cups with HA/TCP coating. The migration of the cup center was not significantly influenced. Evaluation of femoral head penetration in 12 of the matched pairs did not reveal any significant difference. Immediately after operation, implants with HA/TCP coating had more central radiolucencies, which, despite minimal migration, disappeared during the follow-up. The clinical results did not differ between the 2 groups. The findings of less tilting and diminishing radiolucencies in the cups with HA/TCP coating suggest a more complete ingrowth of bone and a better sealing of the interface.

Bone Screws↗
PubMed1999

The Charnley versus the Spectron hip prosthesis: clinical evaluation of a randomized, prospective study of 2 different hip implants.

Prospective, randomized studies must be performed when new surgical techniques or implants are evaluated. In this study, a new implant system was compared with the Charnley prosthesis, which over the years has been the most used hip implant in Sweden. Between 1985 and 1989, 410 hips were randomized to treatment with a Charnley or a Spectron total hip arthroplasty: 206 Charnley and 204 Spectron prostheses were implanted. The patients were operated on by a standardized procedure using a contemporary cementing technique. The patients were followed prospectively by an independent observer after 1, 3, 5 to 6, and 10 years. Harris Hip Score and patient satisfaction were recorded in the outcome evaluation. A total of 144 patients with 164 hips were deceased, and 15 patients (8 Charnley and 7 Spectron) have required a revision. Nine hips were revised because of aseptic loosening (5 Charnley stems and 4 Spectron metal-backed cups). The Charnley stem as well as the metal-backed Spectron cup had a higher risk for revision because of aseptic loosening. The Charnley ogee cup and the Spectron stem have performed remarkably well with no revision of these components. Seven Charnley prostheses dislocated, but no dislocation was recorded in the Spectron group. Survivorship calculations with a mean follow-up of 10 years revealed an overall 11-year survivorship of 94.5% +/- 3.4% (Charnley, 93.2% +/- 5.8%; Spectron, 95.9% +/- 3.0%). The clinical outcome did not differ between the 2 systems. The overall results in this old population, using a contemporary surgical technique, illustrate that cemented hip arthroplasty is an excellent treatment alternative for elderly patients.

Aged↗
PubMed1999

The Charnley versus the Spectron hip prosthesis: radiographic evaluation of a randomized, prospective study of 2 different hip implants.

A total of 410 hips were randomized to treatment with either a Charnley (206 hips) or a Spectron (204 hips) total hip arthroplasty. The patients were operated on by a standardized procedure using a contemporary cementing technique and were followed after 1, 3, 5 to 6, and 10 years. The postoperative radiographs showed a significantly increased rate of malalignment and consequently low grade of cement mantle quality of the Charnley stem compared to the Spectron. No differences concerning cement mantle quality or positioning were found between the Charnley ogee cup and the metal-backed Spectron. Evaluation of the follow-up radiographs revealed 10 loose Charnley stems and 1 loose Spectron stem and 4 loose Charnley ogee cups and 23 loose Spectron metal-backed cups. The differences of revision rate for the femoral and acetabular components of the 2 prostheses were significant (P = .03, Charnley femoral component more frequent; P = .03, Spectron acetabular component more frequent). The radiographic evaluation strengthened this disparity. Poor wear characteristics of the metal-backed Spectron cup are perhaps the main reason for the highly significant difference in mechanical failure rate between the 2 cups. We therefore propose that metal-backing of cemented cups should be avoided, at least when combined with larger femoral heads. The difficulty in positioning the Charnley stem with an adequate cement mantle, especially in the absence of trochanteric osteotomy, might explain the inferior Charnley stem longevity in this study.

Aged↗
PubMed1999

No biological advantage with a low temperature curing versus a conventional bone cement: an experimental, mechanical and histomorphometrical study in the rabbit tibia.

Both tibial marrow cavities of 12 rabbits were evacuated and filled with curing bone cement. In one of the tibias conventional curing bone cement (Simplex P) was injected, while the other tibia of the same animal was filled with a low temperature curing bone cement (Boneloc). Three titanium implants were inserted along the proximal metaphysis of each tibia. Eight weeks after insertion the most distal implant in each tibia was removed while recording the removal torque. The implant was then once again screwed home into its bone bed. The animals were sacrificed 16 weeks after implant insertion. The previously removed implant and another implant in each tibia were then both removed while recording the removal torque. The third implant in each tibia was cut out en bloc with surrounding tissue and processed for ground section. We found no statistical differences in the mechanical or the histomorphometric evaluation of implant integration between the two cements, indicating that the low temperature curing bone cement does not result in a significantly different bone response from that of a conventional acrylic cement.

Journal Article↗
PubMed1999

Subsidence of a non-polished stem in revisions of the hip using impaction allograft. Evaluation with radiostereometry and dual-energy X-ray absorptiometry.

We revised 24 consecutive hips with loosening of the femoral stem using impaction allograft and a cemented stem with an unpolished proximal surface. Repeated radiostereometric examinations for up to two years showed a slow rate of subsidence with a mean of 0.32 mm (-2.0 to +0.31). Fifteen cases followed for a further year showed the same mean subsidence after three years, indicating stabilisation. A tendency to retroversion of the stems was noted between the operation and the last follow-up. Retroversion was also recorded when displacement of the stem was studied in ten of the patients after two years. Repeated determination of bone mineral density showed an initial loss after six months, followed by recovery to the postoperative level at two years. Defects in the cement mantle and malalignment of the stem were often noted on postoperative radiographs, but did not correlate with the degrees of migration or displacement. After one year, increasing frequency of trabecular remodelling or resorption of the graft was observed in the greater trochanter and distal to the tip of the stem. Cortical repair was noted distally and medially (Gruen regions 3, 5 and 6). Migration of the stems was the lowest reported to date, which we attribute to the improved grafting technique and to the hardness of the graft.

Absorptiometry, Photon↗
PubMed1999

Poor outcome of the PCA and Harris-Galante hip prostheses. Randomized study of 171 arthroplasties with 9-year follow-up.

155 patients (171 hips) with a mean age of 50 years (24-64) were randomized to uncemented PCA (84 hips) or Harris-Galante type I (87 hips) total hip arthroplasty. Clinical and radiographic evaluations were done regularly. The improvements in the Harris hip and pain scores did not differ. Osteolysis developed in 5 PCA and 17 Harris-Galante hips. 13 hips in the PCA and 16 in the Harris-Galante (HG) group were revised because of mechanical failures and 1 hip (HG) because of infection after a mean follow-up of 9 years. Decreased 10-year survival rate, based on revision as end-point, was noted for the PCA (85%), compared with the Harris-Galante cup (99%). The corresponding survival rate of the PCA stem (96%) was higher than that observed for the Harris-Galante design (86%). When radiographic failures were included, the survival rates of the 4 different components dropped to between 73% and 94%. These findings indicate that further revisions will be necessary and continuous radiographic follow-up is indicated to enable revision before severe bone destruction has occurred. Although the PCA and the Harris-Galante designs differed as regards the survival of the individual components, the overall clinical and radiographic survival rates of these cementless total hip arthroplasties were poor.

Adult↗
PubMed1999

The economics of preventing revisions in total hip replacement.

We showed that the selection of a cost-effective type of cement and method of prophylaxis against deep infections for patients undergoing total hip replacement depended on the number of arthroplasties performed each year at individual hospitals. When 100 arthroplasties were performed each year, the use of Palacos cement and systemic antibiotics reduced the total costs to the department, i.e., the cost of cement, infection prophylaxis and revisions. The use of gentamicin-impregnated cement in combination with systemic antibiotics will further reduce the risk of revision and is another cost-effective strategy. The most effective infection prophylaxis would be achieved with a combination of gentamicin-impregnated cement, systemic antibiotics and surgical enclosure. However, the additional cost of the surgical enclosure would not be offset by cost savings due to reduced risk of revisions.

Anti-Bacterial Agents↗
PubMed1998

Specific or general health outcome measures in the evaluation of total hip replacement. A comparison between the Harris hip score and the Nottingham Health Profile.

We assessed 100 patients with a primary total hip replacement using the Harris hip score and the Nottingham Health Profile at one, three and five years after operation. They were derived from two prospective randomised series of cemented and uncemented replacements. Both scoring systems correlated highly and were each heavily influenced by the system of functional classification defined by Charnley. After five years both reflected the function of the implant and the general state of the patient. A higher degree of sensitivity is needed to show differences in the performance of an implant in the short and medium term. We do not yet have an ideal system of clinical assessment and the overall function must always be properly assessed.

Activities of Daily Living↗
PubMed1998

Fixation and metal release from the Tifit femoral stem prosthesis. 5-year follow-up of 64 cases.

We stratified the fixation of the femoral component in 64 hips with degenerative joint disease into 3 groups, cemented (C), proximal hydroxyapatite coating (HA) or proximal porous coating (P). All implants had the same basic design and were made of TiAIV alloy. The migration of the implants was assessed by radiostereometry. After 5 years, the mean subsidences in the cemented and porous-coated groups were 0.16 and 0.31 mm, whereas the HA-coated implants displayed a mean proximal migration of 0.1 mm. 7 stems (2 C, 1 HA, 4 P) showed a continuous subsidence (> 0.25 mm) between the 2- and 5-year follow-up. 1 porous-coated stem was revised after the 2-year follow-up, because of pain and implant failure (previously reported) and 1 cemented stem was revised after 5 years because of pain and osteolysis. In a subset of patients, all with a femoral head made of aluminum oxide, the levels of metal were determined using atomic adsorption spectrometry. Subsidence of the stem between the 2- and 5-year follow-up was associated with increased levels of aluminum in the blood at 2 years. Generation of metallic particles from abrasive wear of the stem followed by third body abrasion of the ceramic femoral head could be one explanation of this finding. 5 hips which had shown high levels of titanium and aluminum in joint fluid at the 2-year follow-up displayed increased subsidence and developed proximal radiolucencies or osteolysis at the 5-year follow up. One of these was the cemented hip which was subsequently revised.

Adult↗
PubMed1998

Life expectancy and cost utility after total hip replacement.

In a prospective study of 410 cemented hip replacements in 372 patients with a mean age of 71 years, mortality after 8 years was 33%. Mortality for patients with osteoarthrosis was lower than in an age matched control population, probably because of a preoperative selection of patients. An estimate of costs and adjusted quality of life has shown that total hip replacement has a good cost utility even in the elderly patient. The conclusion of this study is that the indications for hip replacement in the elderly patient can be expanded. Such patients should undergo surgery earlier in the course of their disease.

Adult↗
PubMed1997

Scandinavian multicenter porous coated anatomic total hip arthroplasty study. Clinical and radiographic results with 7- to 10-year follow-up evaluation.

Four hundred ninety-four patients (539 hips) with a mean age of 50.1 (SD, 9.7) years entered a prospective, multicenter study of the Porous Coated Anatomic (Howmedica, Rutherford, NJ) total hip arthroplasty. The preoperative diagnoses were primary osteoarthrosis (297 hips), secondary osteoarthrosis to childhood diseases (88 hips), fracture (73 hips), inflammatory arthritis (26 hips), idiopathic avascular necrosis (28), and miscellaneous (27 hips). After a mean follow-up period of 6 years and 10 months, 71 hips had been revised. The mean Harris hip score increased from 43 (15.7) to 94 (7.4) at the last follow-up evaluation, without any deterioration with time. After 7 years, the combined survival rate for the cup and/or stem using revision as endpoint was 92.2%. Radiographic failure, defined as migration of either component more than 5 min and/or focal osteolysis, was registered in 72 stems and 96 cups. The combined clinical (revision) and radiographic 7-year survival rates were 61.1 (+/-5.2) and 59.7 (+/-5.3) for the stem and cup, respectively. Statistical analysis revealed that young age and poor fill rate influenced the rate of stem failure, whereas cup failure was difficult to predict. Four variables were associated with stem subsidence: loosening of beads, pedestal formation, sclerotic lines in Gruen zone 7, and acetabular granuloma. According to our findings, the 5- to 10-year complication rate with this implant is high. Therefore, continuous radiographic follow-up evaluation of these cases is strongly recommended, to enable revision before severe destruction of bone or catastrophic clinical failure has occurred.

Adult↗
PubMed1997

Osteoarthrosis of the hip in women and its relation to physical load at work and in the home.

OBJECTIVES: The aim of this case referent study was to investigate the relation between physical workload and osteoarthrosis of the hip in women. METHODS: The study base comprised all women of ages 50-70 years, living in five counties and four towns in Sweden 1991-1994. Cases (n = 230), who had undergone total hip replacement for primary osteoarthrosis of the hip were identified by means of the Swedish National Register of Total Hip Replacements, and the referents (n = 273) were women without hip problems randomly selected from the study base. All women were interviewed about state of health, smoking habits, occupational history, work in the home, sports activities, etc. Each subject's history of occupational work and work in the home up to the age of 50 was divided into periods within each of which the work tasks were similar, and a questionnaire for each such period was filled in by the participants. On the basis of information given by the referents, the women were classified as having had low, medium, and high exposure to different factors. Relative risks (RRs) and 95% confidence intervals (CI) were calculated. RESULTS: Physically demanding tasks at work and in the home were associated with increased RRs of osteoarthrosis of the hip in those with high exposure compared with the low exposure group. A RR in the range of 2 or higher was found for those who frequently jumped or moved between different levels (RR = 2.1, CI 1.9, 4.2), who frequently climbed stairs (RR = 2.1, CI 1.2, 3.6), and who had physically demanding tasks outside occupational life (RR = 2.3, CI 1.5, 3.6). The highest RR (RR = 4.3, CI 1.7, 11.0) was found for those exposed to high physical loads both at work and during sports activities. CONCLUSION: High physical loads at work and in the home up to the age of 50 seem to be risk factors for development of severe osteoarthrosis of the hip in women.

Aged↗
PubMed1997

Lifestyle factors and hip arthrosis. A case referent study of body mass index, smoking and hormone therapy in 503 Swedish women.

We investigated in a case-referent study the relationship between arthrosis of the hip in women and lifestyle factors such as body mass index (BMI), smoking and hormone therapy. The study comprised all women of ages 50-70 years, living in 5 counties and 5 towns in Sweden 1991-1994. The cases (n 230) were women with total hip replacements (THR) because of primary arthrosis, and the referents (n 273) were randomly selected women from the study base, without hip problems. All women were interviewed about height, weight, smoking habits, hormone therapy, sports activities, occupational history, home work, etc, to the age of 50. The relative risk of developing hip arthrosis leading to a THR after the age of 50 was associated with an increased BMI. The highest value, 2.9 (Cl 1.3-6.5), was reported in those with BMI > or = 25 at the age of 40. The preventive value of weight loss seems substantial. There was a greater risk of 1.5 (Cl 1.0-2.2) for smokers than for non-smokers. Use of contraceptive pills meant an increase in the relative risk for THR, unlike estrogen substitution which was associated with a lower risk than in unexposed persons.

Aged↗
PubMed1997

How outcome studies have changed total hip arthroplasty practices in Sweden.

The Swedish Hip Registry has defined the epidemiology of total hip replacement in Sweden. Most hip implants are fully cemented. Serious complications and rates of revision associated with total hip replacement have declined significantly despite an increasing number of patients at risk. During the past 5 years only 9% to 10% of hip replacement procedures are revision procedures. Aseptic loosening with or without osteolysis is the major problem and constitutes 73% of the revisions, but the incidence has decreased four times during the past 15 years to less than 3% at 10 years. Even septic complications can be prevented effectively. Demographics are important because male gender and young age increase the risk for revision because of aseptic loosening. Young female patients with rheumatoid arthritis and male patients with a previous hip fracture have five times higher revision rates than elderly patients. The quality of the surgical technique is the most important factor for reducing the risk for revision because of aseptic loosening, but choice of implant is also important. The variations among hospitals in type of surgical technique used is big enough to cause a 100% difference in revision rate for aseptic loosening. Total hip replacement practice in Sweden has improved based on information from this Registry about individualized patient risks, implant safety, and the efficacy of improving surgical and cementing techniques.

Arthroplasty, Replacement, Hip↗
PubMed1997

Radiostereometry of hip prostheses. Review of methodology and clinical results.

Radiostereometric analysis is a science that enables reliable measurements to be made from radiographs. The method involves several steps including insertion of spheric tantalum markers, radiographic examinations, measurements of radiographic films, and calculations of three-dimensional movements. The precision of the method corresponding to the 99% significance interval varies between 0.15 and 0.6 mm and 0.3 degree and 2 degrees when applied to total hip replacement depending on the technique used. Measurements of implant micromovement during 1 to 2 years after surgery have proved to be of value to predict later clinical failure because of aseptic loosening and revision. Subsidence of the femoral stem or proximal migration of the acetabular cup between 1 and 2 mm has indicated increased risk of early or intermediate term revisions in those prosthetic designs studied so far. Minimum early migration has been recorded for clinically well documented nonpolished stems and polyethylene cups, which probably is one explanation for their long term success. This small amount of early micromotion also has been found in porous coated and screw fixated press fit cups and all hydroxyapatite coated designs hitherto studied. As a first step in a clinical evaluation of new implants or surgical techniques, the predictive value of radiostereometric analysis measurements can be used to reduce the number of patients exposed to the potential risk of clinical failure.

Arthroplasty, Replacement, Hip↗
PubMed1996

Migration of press-fit cups fixed with poly-L-lactic acid or titanium screws: a randomized study using radiostereometry.

The early migration of porous acetabular cups was studied in 43 patients with osteoarthrosis. The patients were randomly allocated to additional fixation of the cup with either biodegradable poly-L-lactic acid screws or titanium screws. Radiostereometric evaluation was done during the first 2 years after the procedure in 43 hips (23 with poly-L-lactic acid screws and 20 with titanium screws). At the 2-year follow-up, cups fixed with poly-L-lactic acid screws had migrated significantly more in the proximal-distal (p < 0.05) and medial-lateral (p < 0.05) directions. Cups with titanium screws displayed more pronounced rotations around the longitudinal axis (p < 0.05). Postoperatively, on the lateral view, there was an increased occurrence of radiolucencies at the dome of the cups fixed with poly-L-lactic acid screws (p < 0.05). The clinical result did not differ between the two groups. Inferior implant-bone contact in the poly-L-lactic acid group, local changes of the bone quality, and diminishing support of the poly-L-lactic acid screws caused by their degradation with time could be reasons for the different pattern of migration observed.

Acetabulum↗
PubMed1996

Long-term clinical and radiological results of the Lord total hip prosthesis. A prospective study.

We enrolled 98 patients (107 hips) with a mean age of 47 years (SD 8.6) into a prospective study of the Madreporic Lord THR; 34 hips had primary and 73 secondary osteoarthritis. After ten years, the survival rate using revision as the endpoint for failure was 70% (+/-9) for the cup and 98% (+/-0.3) for the stem. The combined clinical and radiological survival rates were 46% (+/-11) and 81% (+/-10), respectively. Osteoporosis due to stress-shielding was observed in the proximal femur. Hips with radiologically dense bone postoperatively showed the most pronounced bone loss. We recommend continued radiological follow-up of patients with this type of implant to allow revision to be performed before there is severe bony destruction of the pelvis.

Acetabulum↗