Biomedical subjects
Publications and source records attributed to B Mjöberg.
Injury or entrapment of the superficial radial nerve is common in external fixation for fractures of the distal radius. However, by insertion of the half pins dorsally (rather than dorso-radially) in the diaphysis of radius, the nerve should be safe. None of the 40 patients we treated with this safer position of the pins developed symptoms related to the superficial radial nerve.
According to the Papineau technique, open autogenous cancellous bone grafting procedures were performed in tibial bone defects. Repeated positron emission tomography (PET) examinations with 2 tracers, [15O]water to assess blood flow and [18F]fluoride to assess bone metabolism, showed no evidence of recirculation of the bone graft within the first week.
The aluminium content in bone has been related in several ways: to the weight of wet bone, to the weight of dry bone, to the weight of bone-ash and to the calcium content of bone. We determined the accuracy and precision of measurement (using an inductively coupled mass-spectrometer) in 30 bone samples taken from one patient. The coefficient of variation of the aluminium/weight-quotient was 12.4 per cent for wet bone, 4.7 for dry bone and 5.0 for bone ash; and the coefficient of variation of the aluminium/calcium-weight-quotient was 7.5 per cent. Thus, the aluminium content in bone seems to be best related to the weight of dry bone.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The incidence of fragility fractures has increased epidemically. Especially patients with senile dementia (including Alzheimer's disease) have a greatly increased risk of fragility fractures. Aluminum inhibits bone mineralization; the greater the aluminium exposure, the higher the risk of an early fracture. Aluminium is neurotoxic and may, in addition to genetic factors, play a role in the development of Alzheimer's disease by contributing to the formation of the characteristic beta-amyloid and neurofibrillary tangles. Thus, a common denominator between Alzheimer's disease and bone fragility may be a chronic low-grade aluminum intoxication. The epidemic of fragility fractures may be caused by increased aluminium exposure--due to the use of aluminum cooking pots or the pollution acidification of our environment. In our pilot study of 26 hip-fracture patients (13 patients with Alzheimer's disease and 13 individually age- and gender-matched non-demented patients), the aluminum content, determined mass-spectro-metrically, was higher in trabecular bone biopsies from the patients with Alzheimer's disease than from the non-demented patients (p = 0.005). The aluminum content was also higher in the younger of the 26 patients (p = 0.02). Our findings agree with the hypothesis that aluminum plays a role in the development of Alzheimer's disease and bone fragility.
The issue of prosthetic loosening is currently a matter of debate, particularly with regard to the timing and nature of the precipitating events. The theory presented here postulates that loosening begins at an early stage due to either insufficient initial fixation or early loss of fixation. The loosened prosthetic component is then affected by varying degrees of mechanical stress associated with normal daily activity, which differs according to patient characteristics (body weight and level of physical activity) and the components used (prosthetic design, positioning, friction, and wear). This theory of early loosening can explain without supplementary ad hoc assumptions the rapid early prosthetic migration detected by roentgen stereophotogrammetry, the development of focal osteolysis and wear granulomas, the phenomenon known as stress-shielding, and, to a great extent, the epidemiology of clinical failure.
We studied the epidemiological features of tibial shaft fractures during two 5-year periods, 1971-75 and 1986-90, in the county of Uppsala, Sweden. The incidence was higher in men than in women during both periods. In men aged 10-19 years, the fracture incidence was lower during the second period, with a reduction of fractures sustained in road traffic accidents. In women above 80 years, the fracture incidence was higher during the second period.
The migration of an acetabular component, revised 12 years postoperatively, was clearly detectable within the first year after operation by roentgen stereophotogram analysis. The failure was probably the result of an early initiated prosthetic loosening.
Sixty-eight closed tibial shaft fractures were treated with an anterior unilateral external fixator over a 5 year period (1986-1991). Pin tract drainage and/or infection was seen in 71/380 pins. The total number of secondary operations, excluding planned pin extraction, during fracture healing was 61 (including 22 due to pin tract problems and 25 secondary corrections of alignment). Delayed union was seen in 14 fractures and non-union in three. Healing disturbances were more frequent following high-energy trauma. Bone grafting was done in 11 fractures. Eventually, all fractures healed within an average of 22 weeks. There were three refractures. At follow-up, on average 3 years after injury, functional results were excellent in 41 per cent, good in 46 and acceptable in 13 per cent. Due to the high number of unplanned secondary operations and prolonged healing times we do not consider the use of unilateral external fixation to be an adequate method for the treatment of closed tibial shaft fractures. The poor results are probably due to weight-bearing being too high in these patients relative to the mechanical stability provided by the external fixator system.
The accuracy of three methods (the simple and noncomputerized Scheier-Sandel and Charnley-Duo methods and the computerized Ein Bild Roentgen Analyse [EBRA] method) for retrospective wear measurements of the acetabular cup from standard pelvis radiographs was studied. Measurements on 13 hip prostheses were compared with those obtained by roentgen stereophotogrammetry analysis. The Scheier-Sandel method had the lowest accuracy and the EBRA method had the best accuracy. The Charnley-Duo method was almost as good when starting analysis 3 months after surgery and is easier to use. The EBRA method is useful for accurate measurements on a small number of patients; the Charnley-Duo method is recommended for clinical wear studies on a larger number of patients.
We treated 37 infected tibial shaft nonunions by debridement followed by open autogenous cancellous bone grafting in a 2-stage procedure. Additional surgery was done in 21 fractures including second debridement before bone grafting and/or a second limited bone grafting and/or a split-thickness skin grafting. All fractures healed after an average of 11 (8-16) months. During 2 years follow-up there were no recurrences of the infection. Two cases of early refracture occurred, both healed following new bone grafting.
The observation of perioprosthetic granulomas containing wear debris around apparently well-fixed as well as around loose-fitting prosthetic components has led to the development of the hypothesis of wear-induced loosening. However, the hypothesis of wear-induced loosening can neither explain the rapid early prosthetic migration detected by roentgen stereophotogrammetry nor the epidemiology of clinical failure without supplementary ad hoc-assumptions. By contrast, apart from explaining the rapid early prosthetic migration detected by roentgen stereophotogrammetry, the theory of early loosening can explain the development of wear granulomas as well as to a great extent the epidemiology of clinical failure.
Nineteen patients with juvenile chronic arthritis underwent 29 resurfacing hip arthroplasties. In 22 the original all-plastic Wagner acetabular component was used and in 7 the metal-backed Wagner-Tillmann component. After a mean of 11 (range 8-13) years 19 of the Wagner acetabular components had been revised and another 2 showed radiographic loosening. After a mean of 7 (range 5-9) years no metal-backed acetabular cup had been revised and only 1 was definitely loose.
Roentgen stereophotogrammetric analysis (RSA) was used to evaluate the migration in 17 cemented acetabular components after revision operations for mechanical loosening. All of the hips were examined four months and one year after surgery; ten of the hips were also examined after two years. In 15 of the 17 components, definite migration (0.5-2.7 mm) was identified, whereas two acetabular components showed no significant migration (< 0.25 mm). In 13 hips, the migration was seen within four months after surgery. There was a tendency for larger migration in revisions for severe bone destruction. These findings indicate that prosthetic fixation in revision operations is relatively poor. In cases with severe bone loss, cement fixations is extremely poor.
Four different methods of radiologic evaluation of the acetabular component migration following total hip arthroplasty have been compared with roentgen stereophotogrammetry, a proven highly accurate method for studying early migration. In the Sutherland and Wetherell method the implant's position is measured with a pencil and a ruler from an ordinary pelvis radiograph. New reference lines of the Wetherell method are thought to be more accurate. The Sulzer and EBRA methods are computerized. In the Sulzer method prominent bone markers are digitized and used as reference points. In the EBRA method a system of tangents on prominent pelvis structure is digitized and used to detect radiographs with similar projection. The implant's position is calculated as the mean position of similar radiographs. The Sutherland, Wetherell, and Sulzer methods had almost the same accuracy, whereas the EBRA method was more accurate and could be used for pro- and retrospective studies in a large number of patients.
Explore the source record for details and available documents.