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Biomedical subjects

K Jonsson

Publications and source records attributed to K Jonsson.

At least 37 records · Page 2Linked to original sources
PubMed2001

Effect of sorption kinetics on the transport of solutes in streams.

To provide an appropriate description of the transport of a reactive substance in a stream, it is important to include a kinetic description of sorption in a transport model. In this study, first-order sorption kinetics was taken into account in both the transient storage zone and the stream water, and analytical expressions for relative error in statistical moments of the residence time PDF, resulting from disregarding sorption kinetics, were derived. The sorption rate coefficient in the water was found to influence the error in the expected value, and the error was found to approach infinity as the travel distance or sorption rate coefficient approaches zero. The sorption rate coefficient in the storage zone influences only higher-order moments. For sufficiently long distances, the error in the variance was found to be more pronounced when sorption kinetics in the storage zone was disregarded, than when sorption kinetics in the stream water was disregarded. Parameter values from a tracer experiment with 51Cr revealed that the relative error in the variance could be more than 100%, if sorption kinetics in the storage zone is disregarded.

Journal Article↗
PubMed2001

Retention of conservative and sorptive solutes in streams--simultaneous tracer experiments.

The effective transport velocity of solutes in rivers and streams is governed by transient storage in hyporheic zones in which the longitudinal advection velocity is small relative to the main stream flow velocity. Results from a simultaneous tracer experiment using a non-reactive (tritium, 3H2O) and a sorptive tracer [chromium, 51Cr(III)] have formed the basis of a more accurate interpretation of the retention characteristics of solutes in streams than previously has been possible. By using a simultaneous injection of these two tracers, it was possible to distinguish between their different behaviours. Based on estimations of fluxes, the retained mass of chromium in the storage zones along the 30-km-long study-reach was 76% after 150 h. Independent observations in the bed sediment indicated that the loss of chromium observed in the water was mainly a result of uptake into the bed sediment. To describe the transport in the stream, a model concept including solute sorption kinetics in the bed sediment was proposed. Evaluation of parameters in the model, indicated that the uptake of chromium in the bed sediment is controlled by sorption kinetics.

Journal Article↗
PubMed2001

Magnetic resonance imaging of the knee in chronic knee pain. A 2-year follow-up.

OBJECTIVE: The aim of the study was to evaluate the change over time of cartilage defects, subchondral lesions and meniscal abnormalities of the knee using magnetic resonance (MR) imaging with a 2-year interval in patients with chronic knee pain. DESIGN: In the format of a prospective study of early osteoarthritis (OA), the signal knee (most painful at the inclusion in the study 1990) in 47 individuals, 25 women and 22 men (aged 41-57 years, median 50), with chronic knee pain, with or without radiographically determined knee OA, were examined using MR imaging on a 1.0 T imager with a 2-year interval (median 25 months, range 21-30). Cartilage defects, subchondral lesions and meniscal abnormalities were recorded and compared in blind between the examinations. RESULTS: Five new cartilage defects and eight subchondral lesions appeared during the 2-year interval. Seven defects and seven subchondral lesions disappeared during the same time. Thirty-two out of 93 cartilage defects (34%) and 19 out of 32 subchondral lesions (59%) displayed an increase or a decrease in size over time. A meniscal abnormality appeared in three locations, and disappeared in none. In 14 out of 54 locations (26%) with a meniscal abnormality an increase or a decrease of the abnormality was recorded over time and no abnormality decreased. CONCLUSIONS: After the 2 years of observation it was possible to register, using MR imaging, the appearance, increase, decrease and disappearance of cartilage defects, subchondral lesions and meniscal abnormalities in middle-aged people with chronic knee pain. This has to be considered in studies of the natural course of knee OA as well as in studies of the intraarticular effect of pharmacological treatment aiming at cartilage repair or protection.

Adult↗
PubMed2001

Radiographic measurement of femorotibial rotation in weight-bearing. The influence of flexion and extension in the knee on the extensor mechanism and angles of the lower extremity in a healthy population.

PURPOSE: A system for examination and measurement of the weight-bearing knee was developed earlier on examination equipment used for QUESTOR Precision Radiography (QPR), adapted to computed radiography and to a picture archiving and communication system. In this study the same system was used to develop a method to define "patellar variables" including measurements of the rotation of the femur and the tibia and the patellar translation, between semiflexion and extension, as well as the Q-angle. The aim of this study was to evaluate the reproducibility of these patellar variables and also to establish "normal" reference values for both the patellar variables and the variables in the original QPR system. MATERIAL AND METHODS: For evaluation of the reproducibility 10 volunteers with healthy knees were examined twice. To obtain the reference values, 80 volunteers with healthy knees, 10 females and 10 males within each decade between 20 and 59 years of age, were examined. RESULTS AND CONCLUSION: The reproducibility of the rotation of the femur and the tibia and of the Q-angle was 2--3 degrees (SD) and of the patellar translation about 3 mm (SD). The result from the healthy volunteers will be a useful tool for evaluation of disorders in the knee joint.

Adult↗
PubMed2001

Diagnosis of a patient with oncogenic osteomalacia using a phosphate uptake bioassay of serum and magnetic resonance imaging.

A previously healthy man with no family history of fractures presented with muscle pain, back pain and height loss. Investigations revealed hypophosphataemia, phosphaturia, undetectable serum 1,25-dihydroxyvitamin D and severe osteomalacia on bone biopsy, suggestive of a diagnosis of oncogenic osteomalacia. Thorough physical examination did not locate a tumour. Support for the diagnosis was obtained by detection of phosphate uptake inhibitory activity in a blinded sample of the patient's serum using a renal cell bioassay. On the basis of detection of this bioactivity, a total body magnetic resonance (MR) examination was performed. A small tumour was located in the right leg. Removal of the tumour resulted in the rapid reversal of symptoms and the abnormal biochemistry typical of oncogenic osteomalacia. Inhibitory activity was also demonstrated using the bioassay in serum from two other patients with confirmed or presumptive oncogenic osteomalacia, but not in serum from two patients with hypophosphataemia of other origin. This is the first case to be reported in which the diagnosis of oncogenic osteomalacia was assisted by demonstration of inhibitory activity of the patient's serum in a renal cell phosphate bioassay that provided an impetus for total body MR imaging.

Adult↗
PubMed2001

Femorotibial rotation and the Q-angle related to the dislocating patella.

PURPOSE: To compare the femorotibial rotation, the patellar translation, the hip-knee-ankle angle and the Q-angle in patients with a dislocation of the patella with those of healthy volunteers. Further, the clinically measured Q-angle was compared to that measured by radiography. MATERIAL AND METHODS: A system for measurement of patellar variables was previously developed and applied to 80 healthy volunteers. In the present study, 28 patients (20 women, 8 men) with dislocation of the patella were examined bilaterally. Fourteen patients had habitual dislocations (20 affected knees) and 14 patients traumatic dislocations (17 affected knees). In 20 patients the clinical Q-angle was measured bilaterally by an orthopaedic surgeon and in 9 of these patients also by a second independent orthopaedic surgeon. RESULTS: The most striking finding was that dislocating knees in both groups showed a smaller Q-angle than the healthy knees. Further, the habitual group showed greater relative rotation between the tibia and the femur and an increased patellar translation compared to the traumatic group and to the healthy volunteers. There was a poor correlation between clinical and radiographic measurements of the Q-angle and no correlation was found between two independent clinical measurements. CONCLUSION: Surgical operations aiming at decreasing the Q-angle should be challenged.

Adolescent↗
PubMed2000

Recurrent chromosome aberrations in fibrous dysplasia of the bone: a report of the CHAMP study group. CHromosomes And MorPhology.

The nosologic status of fibrous dysplasia (FD), a well-known and relatively common bone lesion, is controversial. Information collected by the CHromosomes And MorPhology (CHAMP) study group on published and unpublished cases of fibrous dysplasia shows the presence of clonal chromosome changes in at least a proportion of these lesions. The chromosome aberrations found in FD lesions have been quite variable and have included both structural and numerical changes. Two of the three cases investigated at the study group had trisomy 2 as the sole acquired anomaly. Combined with previously published data, +2 and rearrangements involving chromosome band 12p13 have each been detected in 3 of 8 cases with abnormal karyotype of 11 in which chromosomal analysis has been performed, suggesting that FD is a neoplastic lesion rather than a "dysplastic" process, as has been generally believed and as implied by its very name.

Adolescent↗
PubMed2000

A prospective study of suicidal burns admitted to the Harare burns unit.

The aim of this study was to obtain prospective information on suicidal (attempted suicide) burns patients admitted to the Harare burns unit during 1995-1998. Forty-seven patients, 42 females (89%) and five males (11%), evenly distributed throughout the period of study, were included. The median age was 25 years, range 13 to 50 years. Thirty were housewives (64%). Women married according to customary law were the group most at risk. All patients were burnt by flame after dousing themselves with paraffin or petrol. Conflict in love relationships was the most common circumstance leading to attempted suicide. The median Total Body Surface Area (TBSA) burnt was 60%, range 10-90%, for all patients, 25%, range 10-40%, for those who survived and 65%, range 20-95%, for those who died. Surgery was performed on 16 patients (34%). Mortality was 68%. The overall median hospital stay for all patients was 10 days, range 0-322 days, and 5 days, range 0-322 days, for those who died.

Adolescent↗
PubMed2000

Radiation dose and image information in computed radiography. A phantom study of angle measurements in the weight-bearing knee.

PURPOSE: To establish a correlation between radiation dose and diagnostic accuracy when employing a new digital method for angle determinations. The specific intention was to determine how far the radiation dose can be reduced without losing measuring accuracy and to compare this radiation dose with that employed with our conventional method. MATERIAL AND METHODS: An image succession of an anthropomorphic phantom was generated with a computed radiography (CR) system, by reducing the exposure stepwise. The images were archived and transferred to a workstation for evaluation. The intraobserver variation of two angle determinations was used as an indicator of the evaluation accuracy. Patient radiation doses were measured with thermoluminescent dosimeters. The energy imparted, indicating the relative risk associated with exposure to ionising radiation, and the effective dose, which determines the absolute risk, were calculated. RESULTS AND CONCLUSION: No significant correlation was found between patient dose and measuring accuracy within the evaluated exposure interval. At the lowest exposure of the CR system, the energy imparted to the patient was 30 microJ. Compared with our conventional analogue method this is a reduction by 98%. The effective dose was as low as 1.5 microSv. The CR technique creates possibilities to adapt exposure parameters, and thus the radiation dose to the patient, according to the purpose of the investigation.

Ankle↗
PubMed2000

Distal radioulnar instability is an independent worsening factor in distal radial fractures.

Distal radial fractures in patients who are younger than the age when osteoporosis usually develops are different from fractures in the elderly. Arthroscopy has revealed these fractures often have a complex pattern of fracture related chondral and ligament injuries in the wrist. In Lund, Sweden, of the 92 distal radial fractures that occurred during 1 year in patients younger than the age when osteoporosis usually develops, 76 patients were assessed after more than 1 year (range, 14-38 months). The examination included questions, a visual analogue scale for pain, a physical examination, bilateral radiographic assessment, and wrist score determination according to Gartland and Werley. Instability at clinical examination of the distal radioulnar joint was associated with a worse wrist score and doubled the visual analogue measures for pain at rest and pain at load. This instability was not correlated to any radiographic variable at the time of fracture or at followup. The distal radioulnar joint was painful in 17 of the 27 patients with instability. Radiographic scapholunate dissociation did not affect the outcome. However, radiographic osteoarthrosis Grade 1 was associated with a worse wrist score. The outcome was dependent on the stability of the distal radioulnar joint, which in turn was not correlated to any radiographic parameter. Thus, destabilizing ligamentous injuries are thought to be an important cause of residual problems.

Adult↗
PubMed2000

Investigation of ascites--are we doing enough?

A case of ascites with peritonitis is described. Delayed diagnosis might have contributed to the death of our patient. The current tools used in investigating ascites with peritonitis and a review of the existing guidelines for a workup of these patients are discussed. The use of the laparoscopic technique is recommended.

Aged↗
PubMed1999

Radiography in osteoarthritis of the knee.

Osteoarthritis (OA) is a multifactorial process affecting cartilage and subchondral bone. Conventional radiographs are inexpensive and readily available. The increased knowledge with regard to interpreting weightbearing radiographs of the tibiofemoral joint and axial radiographs of the patellofemoral joint will enable these examinations to remain competitive techniques compared with more expensive and sophisticated methods, such as MR imaging, when investigating knee pain to establish the diagnosis and the severity of OA.

Arthrography↗
PubMed1999

A Prospective study on the epidemiology of burns in patients admitted to the Harare burn units.

The purpose of this study was to record the causes and the magnitudes of burn injuries prospectively and to evaluate the outcome of treatment of patients admitted to the burn units in Harare. The median age of the 451 patients included was 6 years (range: 1 month to 71 years), 54% were female and 46% male. The burn injuries were caused by flame in 51% of the cases and hot liquids in 47%. The overall median total body surface area burnt was 13% (range: 0.5 to 99%). Parasuicidal burns (attempted suicides) were noted in 11% of the patients with a median total body surface area burnt of 30% and mortality of 73%. Lodgers were overrepresented in the material. Delayed split skin grafting was done on 26% of the patients and early primary excision and skin grafting on 3%. The overall median hospital stay was 15 days (range: 0 to 229 days). The median hospital stay for patients with delayed split skin grafting was 42 days and that for those with primary excision and split skin grafting was 17 days. The overall mortality was 22%. All patients with burns larger than 65% of the total body surface area died. Burn injuries were more frequent and larger with higher mortality in females than in males. Flame was the major cause of the burns. Self-inflicted burns, noted mainly in young women, resulted in 73% mortality. Primary excision and grafting reduced hospital stay by 60% compared to delayed skin grafting.

Adolescent↗
PubMed1999

Polyethylene wear and synovitis in total hip arthroplasty: a sonographic study of 48 hips.

Forty-six patients (48 hips), operated on with cemented total hip arthroplasty (THA) because of arthrosis, were examined radiographically and sonographically at 10-year follow-up. Polyethylene wear of acetabular cups was measured on conventional non-weight-bearing pelvic radiographs, and the volume of polyethylene debris was calculated. Radiographic signs of loosening were identified. The capsular distance (ie, thickness of the synovium or synovial contents) was measured sonographically. We found a significant correlation between increased volumetric wear and increased capsular distance. Hips with radiographically loose acetabular components had significantly greater volumetric wear and capsular distance than those without signs of acetabular loosening. This relationship was not observed in hips with radiographically loose femoral components. In cemented THA, the volume of polyethylene wear debris and the thickness of the synovium and the synovial contents are related. In the event of radiographic loosening of the acetabular component, they are both increased.

Aged↗
PubMed1999

Bone scintigraphy in chronic knee pain: comparison with magnetic resonance imaging.

OBJECTIVE: To compare increased bone uptake of 99Tcm-MDP and magnetic resonance (MR) detected subchondral lesions, osteophytes, and cartilage defects in the knee in middle aged people with long-standing knee pain. METHODS: Fifty eight people (aged 41-58 years, mean 50) with chronic knee pain, with or without radiographic knee osteoarthritis, were examined with bone scintigraphy. The pattern and the grade of increased bone uptake was assessed. On the same day, a MR examination on a 1.0 T imager was performed. The presence and the grade of subchondral lesions, osteophytes, and cartilage defects were registered. RESULTS: The kappa values describing the correlation between increased bone uptake and MR detected subchondral lesions varied between 0.79 and 0.49, and between increased bone uptake and MR detected osteophytes or cartilage defects the values were < 0.54. The kappa values describing the correlation between the grade of bone uptake and the grade of the different MR findings was < 0.57. CONCLUSIONS: Good agreement was found between increased bone uptake and MR detected subchondral lesion. The agreement between increased bone uptake and osteophytes or cartilage defects was in general poor as well as the agreement between the grade of bone uptake and the grade of the MR findings.

Adult↗
PubMed1999

Norian SRS versus external fixation in redisplaced distal radial fractures. A randomized study in 40 patients.

We compared Norian SRS, an injectable calcium phosphate bone cement, with external fixation in the treatment of redisplaced distal radial fractures by a prospective randomized study in 40 patients (women 50-80 years or men 60-80 years). After rereduction, the fracture was either stabilized by injection of SRS and immobilized with a cast for 2 weeks, or externally fixed with Hoffman's bar for 5 weeks. Each patient was evaluated at 2, 5, 7 weeks and at 3, 6 and 12 months. Functional parameters were grip strength, range of motion and pain. Radiographic parameters were radial angle, ulnar variance and dorsal tilt. The chosen primary effect variable was grip strength at 7 weeks. Patients treated by injection of SRS apatite had better grip strength, wrist extension and forearm supination at 7 weeks. There was no difference in functional parameters at 3 months or later. None of the methods could fully stabilize the fracture: radiographs showed a progressive redislocation over time. The results indicate that SRS can be used in the treatment of unstable distal radial fractures. The more rapid recovery of grip strength and wrist mobility in the SRS group appears to be due to the shorter immobilization time.

Aged↗
PubMed1999

Cervical laminectomy without fusion in patients with rheumatoid arthritis.

OBJECT: The authors performed a prospective study to determine whether cervical laminectomy without simultaneous fusion results in spinal instability. METHODS: Because of clinical and radiographic signs of cord compression, 15 patients with rheumatoid arthritis (including one with Bechterew's disease) and severe involvement of the cervical spine underwent decompressive laminectomy without fusion performed on one or more levels. Preoperative flexion-extension radiographs demonstrated dislocation but no signs of instability at the level of cord compression. Clinical and radiological reexamination were performed twice at a median of 15 months (6-24 months) and 43 months (28-72 months) postoperatively. One patient developed severe vertical translocation 28 months after undergoing a C-1 laminectomy, which led to sudden tetraplegia. She required reoperation in which posterior fusion was performed. No signs of additional instability at the operated levels were found in the remaining 14 patients. In three patients increased but stable dislocation was demonstrated. The results of clinical examination were favorable in most patients, with improvement of neurological symptoms and less pain. CONCLUSIONS: The authors conclude that decompressive laminectomy in which the facet joints are preserved can be performed in the rheumatoid arthritis-affected cervical spine in selected patients in whom signs of cord compression are demonstrated, but in whom radiographic and preoperative signs of instability are not. Performing a simultaneous fusion procedure does not always appear necessary. Vertical translocation must be detected early, and if present, a C-1 laminectomy should be followed by occipitocervical fusion.

Adolescent↗