Physical function and health-related quality of life in young adults with unilateral congenital lower-limb deficiencies.

PURPOSE: The primary aim was to examine if there were differences in physical function and health-related quality of life (HRQoL) between young adults (18 to 35 years) with unilateral congenital lower-limb deficiency (CLLD) who had been surgically lengthened (Surg) and those using lengthening prostheses (Pros). Second, we wanted to compare their health status with an age- and gender-matched reference group (Ref) without CLLD. METHODS: Cross-sectional study including a study-specific questionnaire, clinical examination, two field tests evaluating physical function (the six-minute walk test and the Stair test) and HRQoL questionnaires (Short Form (SF)-36 and EuroQol (EQ)-5D-3L). RESULTS: Physical function and HRQoL did not differ between the two treatment groups. The odds for having painful or disfiguring scars were 18 times higher in the Surg group (n = 16) compared with the Pros group (n = 14). The CLLD group showed significantly reduced physical function compared with the Ref group. HRQoL, measured by the EQ-5D-3L visual rating scale, was significantly reduced in the CLLD group compared with the Ref group, as was the SF-36 physical function domain in both genders. Men with CLLD also showed increased bodily pain and reduced general health (SF-36), while we found a reduction in the emotional role domain in women compared with Ref. CONCLUSION: There were no significant differences in physical function and quality of life in young adults with CLLD treated with surgical lengthening compared with those using lengthening prostheses. Compared with the general Norwegian population, young adults with CLLD had significantly lower physical function and reduced HRQoL in some domains.

Epidemiology of hip fractures in Oslo, Norway.

The incidence of hip fractures in Oslo has shown a secular increase during the past decades. The main aims of the present study were to report the current incidence of hip fractures in Oslo and to determine whether there is a seasonal variation in the occurrence of fractures. Using the electronic diagnosis registers and the lists of the operating theater for the hospitals in Oslo with somatic care, all patients with ICD-9 code 820.X (hip fracture) from May 1, 1996 to April 30, 1997 were identified. Medical records for all identified patients were obtained and diagnosis was verified. Using the population of Oslo on January 1, 1997 as the population at risk, the age- and gender-specific annual incidence rates were calculated. These rates were compared with those for 1988/89 and 1978/79. Outdoor temperature data for Oslo were obtained to study the relation between temperature and number of hip fractures. A total number of 1316 hip fractures was included, of which 78% occurred in women. An exponential increase in incidence with age was observed in both genders. The age-adjusted fracture rates per 10,000 for the age group > or =50 years were 118.0 and 44.0 in 1996/97, 124.3 and 44.9 in 1988/89, and 104.5 and 35.8 in 1978/79 for women and men, respectively. There was no significant seasonal variation in the incidence of hip fractures and no correlation between mean outdoor temperature and number of fractures for each month in 1996/97. The data show that the incidence of hip fractures in Oslo has not changed significantly during the last decade, and it is still the highest reported. The cold climate of Oslo does not seem to contribute to the high incidence.

Vitamin D deficiency and ovariectomy reduced the strength of the femoral neck in rats.

Vitamin D (vit D) deficiency is common in the elderly, and the aim of this study was to investigate whether vit D deprivation in ovariectomized (ovx) and normal rats would reduce fracture strength. Forty mature female Wistar rats were randomized into four groups: two were ovariectomized (ovx) and two were sham-operated (sham). One ovx and one sham group were fed a vit D-deficient diet (Ovx-D and Sham-D), and the control groups were fed normal rat chow (Ovx and Sham) for 12 weeks. Vit D deficiency was substantiated after 12 weeks by undetectable serum concentrations of 25OHD in the Sham-D and Ovx-D groups. 85Sr activity was lower in Sham-D than in the other groups (P < 0.005). Tibial and femoral weights and lengths showed no differences. Distal tibial trabecular bone volume was reduced in both ovx groups compare with sham (P < 0.005). Bone mineral density (BMD) was higher in sham than in Sham-D and both ovx groups (P < 0.005). Femoral area moment of inertia increased and ultimate stress decreased in Ovx-D compared with ovx (P < 0.05). Other biomechanical properties of the femoral shafts did not differ significantly. The femoral neck was significantly weaker in Ovx-D than in the other groups. In conclusion, ovx decreased tibial trabecular bone volume and both ovx and vit D depletion reduced femoral BMD in rats. Vit D depletion reduced the ultimate stress in the femoral shaft, and the combined depletion of estrogen and vit D significantly reduced the fracture strength in the femoral neck. This fits well with clinical evidence of how postmenopausal status combined with vit D deficiency lead to an increased risk of hip fractures, making this animal model a possible tool for investigating measures to prevent such fractures.

Effects of hormonal conditions and drugs on both muscle and bone strength can be assessed in a single rat test.

Strength of both muscles and bone are important for fracture prevention in osteoporotic individuals. Therefore, drugs that are preclinically tested in animals for preventing or treating osteoporosis, and reducing fracture risk, should not only be checked for their effects on bone strength, but also for those on muscle strength. We developed a rat model to measure both in the same animal, using a single test. The model is based on an in vivo, ventral three-point bending test of the lower leg (Nordsletten L. and Ekeland A. J Orthop Res 11:299-304; 1993). This model was developed to test the contribution of triceps surae muscle contraction to the strength of the tibia. We hypothesized that this same test can be applied to determine bone and muscle strength independently, in an absolute sense. To investigate this possibility, the muscle contribution to bone stresses was estimated from mechanical analyses, based on direct assessment of muscle strength in a separate test. Sixteen mature female Wistar rats were used, half of which were ovariectomized. After 12 weeks, the rats were tested in vivo in three-point bending of the right lower leg during muscle contraction, and then the isolated triceps surae muscle strength in the left lower leg was measured separately, in another model. The rats were then killed, and the left nude shafts were tested mechanically in three-point bending in vitro to determine structural strength of the bone alone. Ultimate external bending moments of the in vivo and in vitro tests, maximal muscle force, and geometrical parameters formed the basis for the analysis. While contracting, the triceps surae loads the tibia in axial compression and bending. We found that the axial compressive stress on the bone due to muscle contraction was less than 2.5% of the bending stress this produced. This indicates that muscle contribution to lower leg strength is due almost entirely to the bending moment it produces, counteracting the external moment put on the leg by the testing device. Thus, the difference between the in vivo (lower leg) and in vitro (nude tibia) failure bending moments is approximately equal to the maximal muscle bending moment. This information can be applied to test the effects of hormonal conditions and drugs on both muscle and bone strength independently, in a single rat test, using the aforementioned procedure.

Incidence of hip fracture in Oslo, Norway: differences within the city.

Oslo, Norway has the highest incidence of hip fractures ever reported. There are great differences in life expectancy between city regions in Oslo, and we investigated if there were any differences in incidence of hip fracture within the city. In 1989, all new fractures of the proximal femur in Oslo residents 50 years or older were registered with each patient's address. Patients in nursing homes were registered according to preadmission address. All were localized to one of six city regions. The incidence of fracture of the total population of Oslo in 1 year age groups was projected on the population of the city regions to calculate the expected number of fractures compared with all of Oslo. The ratio between observed and expected number of fractures was calculated for each city region. The rural county of Sogn og Fjordane (S&F) has only two thirds the incidence of hip fractures compared with Oslo, and life expectancy is longer for both genders compared to Oslo. New hip fractures in 1989 were registered in S&F as in Oslo, and the ratio between observed and expected number of fractures calculated as for Oslo city regions. There were 1029 new fractures in Oslo women, and 284 in men. The relative risk (RR) for Oslo city regions using Inner Oslo West as the reference, showed significantly higher RRs for hip fracture in Inner Oslo East in women (1.23, 95% confidence interval 1.03-1.48) and in Inner and Outer Oslo East in men (1.67, 95% confidence interval 1.14-2.24; 1.45, 95% confidence interval 1.00-2.11, respectively). The risk in S&F compared with Inner Oslo West was significantly lower for women, but not for men (RR 0.74, 95% confidence interval 0.60-0.92; RR 0.82, 95% confidence interval 0.56-1.21, respectively). There were differences in annual incidence of hip fractures between different city regions in Oslo for both women and men, and the incidences were higher than in the rural county of S&F.

Effects of clodronate on cortical and trabecular bone in ovariectomized rats on a low calcium diet.

The aim of this study was to evaluate the contribution of a low calcium diet to the cortical and trabecular osteoporosis seen in ovariectomized rats after 7 weeks on a low calcium diet and to investigate the effects of the bisphosphonate clodronate on this development of osteoporosis. Thirty-six mature, female Wistar rats were randomized into four groups: Ovx-B (bisphosphonate) and Ovx-C (control) were ovariectomized, and Sham-Ca (low calcium) and Sham+Ca (normal calcium) were sham operated. The first three groups were fed a low calcium diet (0.01%) and Sham+Ca normal rat chow (Ca 1.1%). The Ovx-B received 10 mg/kg s.c. clodronate daily for nine weeks, and Ovx-C, Sham-Ca, and Sham+Ca received the same volumes of saline. Bone mineral turnover measured as 85Sr-uptake was increased in all low calcium groups compared to Sham+Ca. The Sham+Ca femora had higher dry weight and ash weight than the other groups, and Ovx-C had higher dry weight compared with Ovx-B and Sham-Ca. Calcium content was lower in both Ovx groups compared to both Sham groups. Magnesium was lower in all groups compared to Sham+Ca and higher in Ovx-B compared with Ovx-C. In the femoral shaft, Sham+Ca had significantly higher ultimate bending moment, energy absorption, and deflection compared to the other three groups. Ultimate bending moment was higher in Sham-Ca than in Ovx-C. Stiffness was increased in both Sham+Ca and Ovx-B compared to Ovx-C. The maximum stress in the femoral midshaft was higher in Sham+Ca than in the other groups, and higher in Ovx-B than in Ovx-C. Histomorphometry showed increased medullary area in all low calcium groups compared to Sham+Ca and larger cortical area in Sham+Ca and Ovx-B compared to Ovx-C. Compared to Sham+Ca the trabecular bone volume was decreased to 30% in Sham-Ca and to 9% in Ovx-C, but was unchanged in Ovx-B. The low calcium diet generally increased bone mineral turnover and reduced the tibial bone volume. Femoral changes led to a reduction of cortical fracture strength and maximal stress. Ovariectomy in addition to a low calcium diet reduced femoral strength even more. Daily injections of clodronate to ovariectomized rats on a low calcium diet increased femoral shaft stiffness and maximum stress, and clodronate preserved both trabecular and cortical tibial bone volume completely.

Effect of intensive training on lower leg structural strength: an in vivo study in ovariectomized rats.

The aim of this study was to investigate the effect of training on the in vivo tibial structural strength during the development of post-ovariectomy osteoporosis. Seventeen mature Wistar rats (215 g) were ovariectomized and randomized into two groups. The sedentary control group was kept cage confined, while 3 days postoperatively the trained group started treadmill running with high intensity for 1 h 5 days a week. All were given a low calcium diet (Ca 0.01%). After 8 weeks the animals were anaesthetized and the right lower legs fractured during muscle contraction in three-point ventral bending. The left legs were fractured at the same level after removal of all soft tissues. Histomorphometry of the meta- and diaphysis of the distal tibiae was performed. Weight-gain was higher in sedentary (108 g) than in trained (61 g) rats (P<0.0001). There were no significant differences in mechanical results between the groups at in vivo or in vitro fracture. Correcting for weight-gain differences did not change these results. Histomorphometry showed no differences between the groups. Corticosterone was higher in trained than in sedentary rats (P<0.02), and corticosterone may have had a negative influence both on muscle and bone. The study could not show an effect of high intensity training in the early phase after ovariectomy on in vivo or in vitro fracture strength.

Training increases the in vivo fracture strength in osteoporotic bone. Protection by muscle contraction examined in rat tibiae.

The effect of high-intensity training on the in vivo lower leg fracture strength during muscle contraction was investigated in osteoporotic rats. 20 Wistar rats were ovariectomized and given a low calcium (0.01%) diet. 7 weeks after ovariectomy they were randomized into training (T) and sedentary (S). The S group was kept cage-confined without any intervention. The T group ran on a treadmill with 10 degrees inclination 5/7 days for 8 weeks. A maximum intensity of 27 m/min was reached after 4 weeks. After 8 weeks, the right lower legs of the anesthetized animals were loaded in three-point ventral bending until fracture occurred during electrically-induced muscle contraction. The left tibiae were excised and fractured at the same level as the right tibiae. Weight gain was equal in the two groups. Energy absorption and deflection at fracture were significantly higher in the T group than in the S group in vivo during muscle contraction. In vitro, there were no significant differences in mechanical results. The mediolateral outer diameter was larger in the T group, and the maximal stress that the tibia could withstand was lower than in the S group. We conclude that 8 weeks of high-intensity training of osteoporotic rats increased the structural lower leg strength during muscle contraction. The reduced maximal stress in the training animals indicates a reduction in bone material quality. The increase of in vivo structural strength must reflect an increased protective effect of muscle contraction due to training.

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.

The development of femoral osteopenia in ovariectomized rats is not reduced by high intensity treadmill training: a mechanical and densitometric study.

The effect of treadmill running on the development of osteopenia was investigated in adult ovariectomized (OVX) rats compared with sedentary OVX and sedentary sham-operated rats. The rats were 3 months old with a mean weight of 214 g. OVX rats were fed a low calcium diet (0.01%), and the sham rats received the normal diet (1.1% calcium). The training consisted of treadmill running at a speed of 27 m/minute for 1 hour 5 out of 7 days during a period of 8 1/2 weeks. The weight gain was higher in the sedentary OVX (108 g) than in the training OVX (62 g) and sham-operated rats (61 g) (P < 0.001). Comparing the two OVX groups, training had no significant effects on the development of femoral osteopenia as assessed by mechanical testing of the femoral shaft and neck, and by bone mass measurements by dual energy X-ray absorptiometry (DXA) or by ashing. Comparing all three groups bone mineral content (BMC) and bone mineral density (BMD) were reduced by more than 40% in both the OVX groups compared with the sham-operated rats (P < 0.001). Ash weight and calcium content were reduced by approximately 40% in both OVX groups. Femoral volume and length were 10% higher in the sedentary OVX animals compared with the trained (P < 0.05), indicating that the training had had a negative effect on the growth changes induced by ovariectomy. The fracture strength of the femoral shaft was reduced by 26% and 22% in the trained and sedentary OVX rats, respectively compared with the sham-operated group (P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Muscle contraction increases the in vivo structural strength to the same degree in osteopenic and normal rat tibiae.

The increase in structural capacity due to muscle contraction in the lower leg was investigated in osteopenic and normal rats. Osteopenia was induced by ovariectomy combined with a low-calcium diet (0.01%). The control rats were sham operated and fed a diet containing 1.1% calcium. After 7 weeks the right lower leg of all animals were fractured in three-point ventral cantilever bending during muscle contraction induced by electrical stimulation of the ischiatic nerve. The left tibiae were resected and fractured as each animal's control. During muscle contraction in vivo, the ultimate bending moment, energy absorption, bending stiffness, and deflection were significantly lower in the osteopenic than in the sham-operated animals. However, the increase in mechanical parameters due to muscle contraction comparing the in vivo and resected tibiae in each animal were equally high in the osteopenic and sham-operated animals. Ultimate bending moment in the resected tibiae was 10% higher in the sham-operated animals compared with the ovariectomized, proving mechanically weaker tibiae in the osteopenic rats. In accordance with this, the medullary area of the osteopenic rats was 46% larger in the distal tibial diaphysis, and the ultimate stress the tibiae could withstand was 15% lower in the osteopenic compared with the sham-operated rats. The trabecular bone volume in the distal tibial metaphysis of the osteopenic rats was reduced by 70% compared with the sham operated. This study shows that muscle protection against fracture can be substantial in osteopenic tibia and that it is of the same magnitude as in rats with normal bone mass.

Fracture strength prediction in rat femoral shaft and neck by single photon absorptiometry of the femoral shaft.

The bone mineral content (BMC) and bone mineral density (BMD) of the femoral midshaft from 15 skeletally mature male rats were measured by Single Photon Absorptiometry (SPA), and comparisons made to fracture strength of the femoral diaphysis and the femoral neck. In stepwise regression the factors contributing significantly to the ultimate bending moment of the shaft were BMC and femoral length. BMC correlated strongly with the ultimate bending moment of the femoral diaphysis (r2 = 0.63, P < 0.01). The correlation between BMC and ultimate moment of the femoral neck was moderate (r2 = 0.51, P < 0.01). The correlations between BMD and mechanical parameters were lower than the corresponding values for BMC, with a significant result only for the bending moment of the femoral diaphysis (r2 = 0.48, P < 0.01). In conclusion, BMC rather than BMD, is most predictive for fracture strength of the femur in rats.

Training increases the in vivo strength of the lower leg: an experimental study in the rat.

The effect of training on bone strength has been investigated in rats. After 7 weeks of training, fracture strength of the tibia in vivo during muscle contraction and after resection was assessed. A group of 30 male rats 11 weeks old were randomized to exercise on a treadmill, sedentary (ordinary caging), and inactivity (right-sided patellar tendonectomy) groups. The training group ran on a treadmill with a 10% inclination for 1 h per day. After 4 weeks the animals in all groups were anesthetized and the right lower legs loaded in three-point ventral bending until fracture during electrically induced muscle contraction. The contralateral tibiae were tested correspondingly after resection. Ultimate bending moment, energy absorption to failure, bending stiffness, and deflection were assessed for the in vivo and the resected tibiae. The body weight gain was 37% higher in the sedentary and 57% higher in the inactive animals than in the training group (P < 0.05), indicating a physiologic effect of the training. In the dissected tibiae there were no significant group differences in any of the mechanical parameters, indicating that neither training nor inactivity changed the structural capacity of the tibiae per se. In contrast, there were significant differences between the in vivo tibiae. Ultimate bending moment was 12% higher in the training group than in the sedentary and inactive groups (P = 0.03). Energy absorption in the training group was 11 and 12% higher (not significant) than in the sedentary and inactivity groups, respectively. Bending stiffness was 7 and 17% higher in the training group compared to sedentary and inactivity groups (P = 0.018).(ABSTRACT TRUNCATED AT 250 WORDS)

Secular increase and geographical differences in hip fracture incidence in Norway.

In 1988 and 1989, 2790 hip fractures were reported from the urban population of Oslo (annual incidence per 10,000 in the age group 50 years and older: women 118.7, men 45.4). For the same period, 385 fractures were reported from the rural population of the county Sogn og Fjordane (annual incidence per 10,000 in the age-group 50 years and older: women 74.6, men 36.7). The hip fracture incidence in Oslo had increased for all sex and age groups above 50 years (except women 50-59 years) in the 10-year period 1978/79 to 1988/89. The incidence of hip fractures in Sogn og Fjordane was only 65% of the incidence in Oslo. These results support previous reports on a secular increase and geographical differences in hip fracture incidence.