[Is surgery of patients with hip problems performed too late? Good cost-benefit effects of hip alloplasty].
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Adult↗
Biomedical subjects
H Malchau
Publications and source records attributed to H Malchau.
Evaluation of Boneloc. Chemical and mechanical properties, and a randomized clinical study of 30 total hip arthroplasties.
We evaluated the mechanical, chemical and clinical properties of Boneloc cement using radiostereometry and a series of laboratory tests. Compared to a standard cement (Palacos) the new cement displayed reduced tensile strength, elastic modulus, curing and glass transition temperatures. The amount of MMA extracted during 3 weeks in methanol was smaller for the Boneloc, but the total amount of released monomers was larger. The adhesion to stainless steel and bone did not differ. Radiostereometric analysis during the first postoperative year in 30 patients randomized to fixation of hip prostheses using either of the 2 cements displayed increased proximal migration of the cup and increased stem subsidence when Boneloc had been used. Part of the stem subsidence occurred inside the cement mantle. On the basis of these findings, we conclude that the inferior fixation in the Boneloc group is mainly caused by its mechanical properties. Other mechanisms, such as increased release of monomers, may also be important.
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Accuracy of migration analysis in hip arthroplasty. Digitized and conventional radiography, compared to radiostereometry in 51 patients.
We assessed the accuracy of migration measurements on conventional and digitized radiographs of total hip arthroplasties by comparing the results with radiostereometry (RSA). 4 stem and 3 acetabular designs were studied. 2 of the stem designs and 1 cup design were uncemented. 180 manual and 202 digitized measurements were done on 120 conventional radiographic examinations. The readings on digitized radiographs did not differ from the manual measurements on the same radiographs. A comparison of the measurements from plain radiographs and with RSA of the femoral stems revealed an accuracy (absolute mean + 2 SD) of between 3.9 and 12.3 mm, depending on the choice of landmarks. The greatest accuracy was obtained by using tantalum markers inserted into the greater or the lesser trochanter and the shoulder of the stem. The most medial point of the lesser trochanter proved to be the best bony landmark. Measurements, including both the center of the femoral head and the greater trochanter, were associated with poor accuracy. The accuracy as regards horizontal cup migration varied from 4.4 to 6.5 mm and the accuracy as regards vertical migration varied between 4.4 and 6.3 mm. The intraobserver error (2 SD) ranged from 1.6 mm to 5.6 mm, The corresponding figures for the inter-observer error were 2.6 mm and 6.6 mm, respectively. One of the cemented cup designs was associated with inferior accuracy. Stem design did not affect the accuracy.
Bias↗
Long-term results of Charnley arthroplasty. A 12-16-year follow-up study.
A retrospective, long-term study was initiated to analyze clinical function, failures, and radiographic status in 95 Charnley low-friction arthroplasties performed during 1973-1977. Only patients with primary osteoarthrosis were included, and no patients were lost during the follow-up period. At the follow-up evaluation, 39 patients (41 hips) were deceased. Ten hips were revised (including 3 of the deceased patients), leaving 47 hips available for follow-up evaluation. Four patients (5 hips) were interviewed by telephone, and the remaining 42 hips were examined by the authors. With a mean follow-up period of 14 years, many of the patients had excellent pain relief with a mean Harris hip score for pain of 42 points (maximum, 44 points). Ninety-four percent of the patients were satisfied with their results. The survivorship for all 95 hips was 92% at 10 years and 83% at 16 years. Follow-up radiographs revealed that three (7%) of the femoral components were definitively loose, but only two (5%) of the acetabular components were probably loose. Forty-three percent of the hips had signs of polyethylene wear of the cup. The clinical and radiographic outcome is, in spite of an early cementing technique, very good in this long-term follow-up study.
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Micromotion of femoral stems in total hip arthroplasty. A randomized study of cemented, hydroxyapatite-coated, and porous-coated stems with roentgen stereophotogrammetric analysis.
The fixation of the femoral stem in a total hip arthroplasty was studied in sixty patients (sixty-four hips) with use of roentgen stereophotogrammetric analysis. The hips were randomly stratified on the basis of the age, sex, and weight of the patient; the roentgenographic quality of the bone; and the reason for the operation (primary or secondary osteoarthrosis). The hips were then randomly assigned to one of three types of fixation of the femoral component: insertion with cement, hydroxyapatite coating, or porous coating. Examinations with roentgen stereophotogrammetry were done as long as two years after the operation. Micromotion of the prostheses was evaluated in terms of subsidence or proximal migration and rotations and translations of the proximal-lateral (shoulder) and distal (tip) parts of the prostheses. The clinical results at the two-year follow-up evaluation did not differ significantly between the groups with regard to the Harris hip score or the pain score (p > 0.05 for both; Wilcoxon rank-sum test). There were small or no differences in rotations and micromotions of the shoulder and the tip of the prostheses. Increased subsidence of 0.1 to 0.2 millimeter was recorded for the cemented and the porous-coated prostheses (p = 0.002 and p = 0.02, respectively; Wilcoxon rank-sum test). Thus, proximal hydroxyapatite coating seems to enhance the early fixation of the stem. Conventional roentgenography revealed an increased number of radiodense lines surrounding the porous-coated prostheses. Distal hypertrophy of the femoral cortex was found mainly around the hydroxyapatite-coated prostheses. Proximal resorption of bone and heterotopic ossification occurred to approximately the same extent regardless of the type of fixation used.
Adult↗
A new radiographic method for detection of tibial component migration in total knee arthroplasty.
In a prospective study the accuracy of a new radiographic method, Matched Indicators for Radiographic Assessment (MIRA), used to assess tibial component migration in total knee arthroplasty was evaluated. Radiopaque markers were placed in the tibial component and the tibial metaphysis in a standardized way so that four vertical distances could be measured on standard radiographs. Subsidence during the first postoperative year was measured both with this new method and with roentgen stereophotogrammetric analysis in 27 Freeman-Samuelson total knee arthroplasties. The error of measurement of MIRA was determined using the known error of roentgen stereophotogrammetric analysis. The new method was found to be promising with an accuracy of 1 mm, and the correlation between MIRA and roentgen stereophotogrammetric analysis was high when subsidence exceeded this value. Therefore, subsidence of clinical importance should be detected with MIRA. The method is simple and well suited for routine follow-up examination of large patient materials.
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Prognosis of total hip replacement in Sweden. Follow-up of 92,675 operations performed 1978-1990.
A prospective, national multi-center study of all reoperations after total hip replacement (THR) was started by the Swedish Orthopedic Association in 1979. The material comprises all THR performed in Sweden, presently more than 10,000 yearly or 130 THR per 100,000 inhabitants; uncemented implants have been used in less than 2 percent. The main reasons for revision have been aseptic loosening 79 percent, infection 10 percent, technical error 6 percent, and dislocation 2 percent. The cumulative rate of revision for deep infection has dropped from 0.9 percent to < 0.5 percent for implants inserted 1979 and 1983, respectively. With the Charnley prosthesis as the gold, standard the performance of other prostheses was analyzed. Improved cementation techniques and anti-infection measures have continuously reduced the revision risk. The register demonstrates that the average orthopedic surgeon cannot match the results achieved by experts. However, the vast majority of THR, worldwide, are not performed by experts. Quality-assurance in this sector of orthopedics demands a continuous analysis of the outcome of these operations.
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Prognosis of total hip replacement. A Swedish multicenter study of 4,664 revisions.
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Adult↗
Multicenter clinical trials and their value in assessing total joint arthroplasty.
Multicenter clinical trials (MCT) have an important role in the assessment of total joint arthroplasty. The primary reason for such MCT is the need to have access to a large number of patients. In Sweden, failure after total hip arthroplasty has been recorded prospectively since 1979. Medical records from every reoperation are documented and computer analyzed. This MCT has shown that patient-related, surgical, and implant-related parameters are of importance to rates of failure. There were an increasing number of revisions after total hip arthroplasty in Sweden between 1979 and 1986. Male gender and young age increase the risk of revision. The primary diagnosis is very important for type of failure. The risk of deep infection is small but increases with the number of previous operations. Aseptic loosening has emerged as the main problem and is the cause for 74% of all revisions. Prosthetic design is of utmost importance for the rate of failure, and significant differences exist among different prosthesis types with respect to long-term survival. Finally, this MCT has shown that revisions for total hip arthroplasty in patients younger than 70 years of age eventually have failed in Sweden whenever the cemented technique has been used.
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Normal range of motion of the cervical spine.
To evaluate the normal range of motion of the cervical spine, 70 healthy subjects were studied using radiography and clinical examination. An equal number of men and women were studied; age ranged from 12 to 79 years. Radiographs were taken in the lateral projection during maximal flexion and extension. In the frontal projection, radiographs were taken during maximal bending to the left and right. The radiographs were analyzed on a digitizing tablet linked to a computer, using preset points to indicate the motion between the vertebrae. The intraobserver error of measurement was +/- 1.8 degrees. The range of axial rotation was measured with the aid of a compass placed on the subject's head. The intraobserver error of measurement with this technique was +/- 6 degrees. The largest intersegmental flexion-extension motion occurred between C4/C5 and C5/C6. A linear decrease of motion in all directions, except in flexion, was found with age. There was no statistically significant difference in motion for men and women. The reliability of methods is discussed.
Adolescent↗
Osteoarthrosis of the hip in women and its relationship to physical load from sports activities.
In a case-control study, the relationship between sporting activities and osteoarthrosis of the hip in women was investigated. The study base comprised Swedish women 50 to 70 years of age between 1991 and 1994. Case subjects (N = 230) had had total hip replacements because of primary osteoarthrosis of the hip, and control subjects (N = 273) were randomly selected women without hip problems from the study base. All women were interviewed about sports activities to the age of 50, health status, smoking habits, occupational history, and work in the home. Three exposure classes were defined based on total hours of sports activities aggregated to the age of 50. The relative risks of developing osteoarthrosis of the hip leading to total hip replacement was 2.3 (confidence interval, 1.5 to 3.7) for those with high sports exposure and 1.5 (0.9 to 2.5) for those with medium sports exposure compared with those with low exposure. The relative risks were adjusted for age, occupational physical load, body mass index, hormone therapy, and smoking. Physical load from sporting activities seems to be a moderate risk factor for women for the development of severe osteoarthrosis of the hip. Participation in sports was low, and therefore individual risk estimates for different sports activities were not possible to obtain.
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