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Biomedical subjects

J B Lauritzen

Publications and source records attributed to J B Lauritzen.

At least 37 records · Page 2Linked to original sources
PubMed1996

Decreased bone density of the distal femur after uncemented knee arthroplasty. A 1-year follow-up of 29 knees.

We measured the early adaptive bone remodeling of the distal femur prospectively for 1 year after uncemented total knee arthroplasty (TKA) in 29 knees with primary arthrosis. 18 patients were randomized to receive a PCA Modular femoral component (n 9) or a modified version of the same prosthesis (n 9) with an altered location of the porous coating. The other 11 patients (n 11) formed a consecutive series with the Duracon femoral component. In the trabecular bone above the femoral component, bone mineral density (BMD) was measured in 2 regions of interest (ROI) anteriorly to the fixation pegs (ROI 1) and above the pegs (ROI 2), using dual photon absorptiometry (DPA). There were no differences between the Modular component and the modified version regarding the postoperative decrease in BMD. There was a decrease in BMD in both ROI 1 and ROI 2 with all 3 different femoral components, and in both ROIs the highest bone loss rate was observed during the first 3 months after surgery. On average (n 29), a significant bone loss of 44% and 19% in ROI 1 and ROI 2, respectively, was reached at the 1-year follow-up, compared to the initial values. A decrease of this magnitude in BMD in the anterior distal femur 1 year after TKA may be an important determinant of periprosthetic fracture and later failure of the femoral component. In this experimental set-up, a modified femoral component with an altered location of the porous coating did not influence the development of bone loss.

Absorptiometry, Photon↗
PubMed1996

[Prevention with hip protectors. Biomechanical aspects in falls and hip fractures].

The cascade of events leading to hip fracture is: a fall, protective responses, impact to the hip, local energy absorption and bone strength. A fall from standing height on the hip corresponds to a force of about 3500 N and the bone strength of the proximal femur in elderly women and men ranges between 2000 to 6000 N. Efficient hip protective systems have been developed and may be a significant factor in the prevention of hip fractures among the elderly with propensity to fall and osteoporosis. Theoretically, more than 90 per cent of all hip fractures can be prevented, and a substantial reduction in the rate of hip fractures can be obtained, when systematic intervention programs are initiated among nursing home residents. Prevention of hip fractures among home dwellers may be a greater challenge, although preliminary results seem promising. Improvement in design has made the protectors more compliant and may facilitate the aim of preventing hip fractures.

Accidental Falls↗
PubMed1995

Changes in bone mineral density of the distal femur following uncemented total knee arthroplasty.

The aim of the study was to quantitate changes in bone mineral density (BMD) in the distal femur following uncemented porous-coated total knee arthroplasty. Eight patients with total knee arthroplasties (PCA Primary, Howmedica, Rutherford, NJ) (female:male ratio, 6:2; mean age, 70 years; range, 51-77 years) were scanned by dual-photon absorptiometry within 3 months after surgery and at 2 years. An average decrease of 36% (P = .01) was found in BMD behind the anterior flange of the femoral prosthesis. Proximal to the fixation pegs, BMD increased by 22% (P = .12), but behind the posterior flange of the femoral component, BMD remained unchanged (P = .53). Stress shielding anteriorly in the distal femur occurred in all patients examined 2 years after surgery, and the increase in BMD proximal to the fixation pegs was probably a result of increased and altered mechanical loading.

Absorptiometry, Photon↗
PubMed1995

Changes in bone mineral density of the proximal tibia after uncemented total knee arthroplasty. A 3-year follow-up of 25 knees.

We measured bone remodeling of the proximal tibia prospectively for 3 years after uncemented total knee arthroplasty (TKA) in 25 knees with primary arthrosis. In the trabecular bone below the tibial component, bone mineral density (BMD) was measured in 6 different regions of interest (ROI), using dual photon absorptiometry (DPA). In the tibial condyles, where the change in knee alignment indicated that the load was reduced postoperatively, a fast bone loss of 7-20% was seen during the first 6 months after surgery. A small, but significant increase in BMD of 2-7% was seen in the tibial condyles, where the load was increased. On average, the density for all ROI below the tibial component showed a significant and progressive decrease in BMD, reaching 22% at 3 years follow-up.

Absorptiometry, Photon↗
PubMed1995

Hip fractures in Nordic cities: difference in incidence.

All new hip fractures referred to hospital in 1989 were recorded in seven urban populations from Denmark, Finland, Norway and Sweden. The total population at risk (50 years and older) was 588,427, and 4075 fractures were observed (76.5% women). In all cities an age-dependent increase in incidence was found, and the female incidence was highest. When comparing the incidence rates after direct standardization, significant differences in hip fracture incidence were found between the cities for both women and men. The standardized relative rates seemed to decrease when moving south and east with the lowest rates found in Tampere, Finland. This indicates that factors which differ even between urban populations within a restricted geographical region may have an important impact on hip fracture incidence.

Aging↗
PubMed1993

[External hip protectors against hip fractures. A randomized study in a nursing home].

Most hip fractures seem to be related to trauma near the hip, so a controlled trial was conducted to investigate the effect of external hip protectors on the prevention of such fractures in residents of a nursing home. Ten of 28 wards of the nursing home were randomized to receive external hip protectors; thus 167 women and 80 men were given protectors and 277 women and 141 men no protectors. A fall register was set up for two treatment wards (45 residents) and two control wards (76 residents). There were eight hip and 15 non-hip fractures in the hip protector group and 31 hip and 27 non-hip fractures in the control group. The relative risk of hip fractures among women and men in the intervention group was 0.44 (95% CL 0.21-0.94). None of the 8 residents in the intervention group who had a hip fracture was wearing the device at the time of the fracture. 154 falls were registered and 20% of these falls produced a direct impact to the hip. In 25 falls direct impact to the hip was sustained at a time when hip protectors were not being worn, and six fractures were produced. The study indicates that external hip protectors can prevent hip fractures in nursing-home residents.

Accidental Falls↗
PubMed1993

Effect of external hip protectors on hip fractures.

Most hip fractures seem to be related to trauma near the hip, so a controlled trial was conducted to investigate the effect of external hip protectors on the prevention of such fractures in residents of a nursing home. 10 of the 28 wards in the nursing home were randomised to receive external hip protectors; thus 167 women and 80 men were given protectors and 277 and 141 men no protectors. A fall register was set up for 2 treatment wards (45 residents) and 2 control wards (76 residents). There were 8 hip and 15 non-hip fractures in the hip-protector group and 31 hip and 27 non-hip fractures in the control group. The relative risk of hip fractures among women and men in the intervention group was 0.44 (95% CI 0.21-0.94). None of the 8 residents in the intervention group who had a hip fracture was wearing the device at the time of the fracture. 154 falls were registered and 20% of these falls produced a direct impact to the hip. In 25 falls direct impact to the hip was sustained at a time when hip protectors were not being worn, and 6 fractures were produced. The study indicates that external hip protectors can prevent hip fractures in nursing-home residents.

Accidental Falls↗
PubMed1993

Changing incidence and residual lifetime risk of common osteoporosis-related fractures.

Changes in incidence and lifetime risk of fractures are of major importance in the epidemiology of osteoporosis. We focused on hip fractures in women and men and on radial and humeral fractures in women. The study subjects comprised 4500 women and men 20 years old or more with fractures. In women 1735 fractures of the distal radius, 747 fractures of the proximal humerus, 878 cervical and 635 trochanteric hip fractures were included. In men 273 cervical and 232 trochanteric hip fractures were included. The fractures were registered during the period 1976 to 1984 and changes in age-specific incidence were calculated (chi-squared test for linear trend; p-values less than 0.05 were considered significant). On the basis of life tables and population background data, the lifetime risk was estimated. The incidence of cervical hip fractures in women aged 60-89 years decreased significantly (p < 0.05) during the observation period, while no significant decrease was found in the incidence of trochanteric fractures. No significant changes in incidence were observed in women with radial or humeral fractures, or in men with hip fractures. A women 60 years old with a life expectancy of 81 years had an estimated residual lifetime risk of radial, humeral or hip fracture of 17%, 8% and 14% respectively. A man 60 years of age with a life expectancy of 77 years had an estimated risk of hip fracture of 6%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Radial and humeral fractures as predictors of subsequent hip, radial or humeral fractures in women, and their seasonal variation.

Hip fractures are common in elderly women, and early risk assessment of future hip fractures is relevant in relation to prevention. We studied the predictive value of radial and humeral fractures in women. The influence of weather conditions on the risk was also studied. Women aged 20-99 years with a fracture of the distal radius (n = 1162) or proximal humerus (n = 406) were followed for 0 to 9 years. The relative risk (RR) and 95% confidence limits (CL) of subsequent fracture among women suffering radial or humeral fractures compared with the background population were calculated. Women 60-79 years of age who had suffered a fracture of the distal radius or proximal humerus had relative risks of sustaining a hip fracture of 1.9 (1.3-2.6, 95% CL) and 2.5 (1.3-3.6, 95% CL) respectively. The relative risk of hip fracture was highest within the first years following a fracture of the radius or the humerus. Women suffering an upper extremity fracture (radius or humerus) in snowy or icy weather had a marginally increased risk (RR = 1.3, 0.4-2.3, 95% CL and RR = 1.8, 0.3-3.4, 95% CL) for a later hip fracture. A woman 50 years old with a radial or a humeral fracture had an estimated residual lifetime risk of sustaining a subsequent hip fracture of 17% and 16% respectively compared with 11% for the background population.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Risk of hip fracture after osteoporosis fractures. 451 women with fracture of lumbar spine, olecranon, knee or ankle.

In a follow-up study during 1976-1984, the risk of a subsequent hip fracture was investigated in women aged 60-99 years, hospitalized for the following fractures: lumbar spine (n 70), olecranon (n 52), knee (n 129) and ankle (n 200). Follow-up ranged from 0 to 9 years. Observation time of the 4 different fractures were 241, 180, 469, and 779, person-years, respectively. In women aged 60-79 years with one of the following fractures the relative risk of a subsequent hip fracture was increased by 4.8 (lumbar spine), 4.1 (olecranon), 3.5 (knee) and 1.5 (ankle). The relative risk of hip fracture showed a tendency to level off 3 years after the primary fracture.

Aged↗
PubMed1993

Risk factors for hip fractures. A review.

Risk factors for hip fracture have been reviewed based on case-control and prospective follow-up studies. Falls with impact to the hip, the capacity of energy absorption in soft tissue, and bone strength are closely linked to the risk of hip fracture. Consistently documented risk factors are age, sex, race, low bone mass, low body weight, estrogen deficiency and earlier fracture. Other risk factors are tendency to fall, disability and immobilisation, low physical activity, use of psychotropic/anxiolytic/hypnotic drugs, use of corticosteroid, low calcium intake in the elderly, osteomalacia, thyreotoxicosis, cigarette smoking, chronic alcoholism, diabetes mellitus, insufficient sunlight exposure and a protective effect from thiazide diuretics. Evidence is lacking for risk factors such as heredity, nutrition and medical conditions. No information is available on the combined effects of the different risk factors. Risk estimation of hip fractures should focus on the risk of falls, the capacity of energy absorption and the bone strength. Recent studies indicate that the prevention of hip fractures is realistic, even in the elderly and definitely osteoporotic population when these fundamental risk factors are modified, which has been shown in controlled trials in nursing homes by vitamin D and calcium supplementation or by wearing external hip protectors.

Aged↗
PubMed1992

Protection against hip fractures by energy absorption.

Impact lateral to the hip was noted in 37 of 60 patients with hip fracture. Women with hip fracture (n = 12) had an average 22 mm thick soft tissue cover of the hip as compared to 32 mm in healthy women (n = 27), even for the same body mass index. Experiments where a steel weight was dropped from various heights onto porcine soft tissue showed that a layer of 29 mm could absorb 60% more energy than a 20 mm thick layer before nearly metallic contact would occur, corresponding to a sharp rise in load. If the results are related to conditions in vivo, then the passive protection of soft tissue over the hip is important for the development of hip fractures, and may under certain assumptions explain the higher risk of hip fractures in thin persons. An external hip protection device might therefore prevent some hip fractures.

Adult↗
PubMed1989

[A comparative study of the Lixiscope and conventional X-ray in fracture diagnosis].

The Lixiscope is a portable hand-held real time imaging device, weighing 3 kg, with an iodine-125 source. The Lixiscope was compared with conventional x-ray. An in vitro experiment trial of the Lixiscope on a transected ox bone, and an in vivo experiment with 24 patients from the Accident & Emergency Department, were made. The diagnostic specificity for two doctors was found to be 0.67 and 1.00 and the diagnostic sensitivity was 0.78 and 0.84. The Lixiscope may be used in the Accident & Emergency Department, and similary in situations where x-ray is not avaiable the Lixiscope seems to be valuable.

Arm Injuries↗
PubMed1987

Heart rate responses to moderate linear body accelerations: clinical implications in aeromedical evacuation.

Linear accelerations during take-off and landing were measured in both civilian and military aircraft usually involved in aeromedical evacuations in Denmark. Accelerations of similar durations and magnitudes were induced in six healthy subjects transported in an ambulance in different supine positions. Heart rate responses recorded depended significantly on the position of the subject. It was concluded that seriously ill patients must be positioned transversely to the axis of acceleration during aeromedical evacuation.

Acceleration↗
PubMed1986

Duodenal output of lactoferrin in normal subjects and correlation to output of amylase, bicarbonate, and total bile acids.

Nineteen normal subjects were studied before and after pancreatic stimulation. Duodenal flow was quantitated by means of a dilution indicator technique, and the secretion pattern of lactoferrin, amylase, total bile acids, and bicarbonate was studied. Output of lactoferrin in the duodenum was increased both after stimulation with a test meal and after hormonal stimulation by cholecystokinin alone or cholecystokinin in combination with secretin. Output of lactoferrin was not affected by stimulation by secretin alone. Lactoferrin was secreted in parallel with amylase and bile acids. The results indicate that the origin of lactoferrin in duodenum can be bile or pancreatic juice, or a combination of these.

Adult↗
PubMed1986

Duodenal output and concentration of lactoferrin in chronic pancreatitis: correlation to amylase secretion and duct morphology.

To evaluate the clinical value of lactoferrin determination in duodenal contents in patients with chronic pancreatitis, three different studies were performed. No significant difference in meal stimulated output or secretion pattern was found between seven patients with chronic pancreatitis and six controls. After a meal test in 88 patients suspected for pancreatitis no correlation between concentration of lactoferrin and amylase was found. No correlation was found between degree of obstruction at endoscopic retrograde pancreaticography and duodenal concentration of lactoferrin. We conclude that the diagnostic value of lactoferrin determinations in chronic pancreatitis is doubtful.

Adult↗