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Biomedical subjects

J Jurvelin

Publications and source records attributed to J Jurvelin.

At least 19 recordsLinked to original sources
PubMed2005

Abnormal response to physical activity in femurs after heterozygous inactivation of one allele of the Col2a1 gene for type II collagen in mice.

The objective of this study was to evaluate the influence of heterozygous inactivation of one allele of the type II collagen gene (Col2a1) on biomechanical properties and mineral density of bone under physical loading conditions. C57BL/6-TGN mice with heterozygous knockout (HZK) inactivation of Col2a1 gene and their nontransgenic littermate controls were housed in individual cages with running wheels for 9 and 15 months. The running activity of each mouse was monitored continuously throughout the experiment. Bone mineral density (BMD) of mice femora was measured using dual-energy X-ray absorptiometry (DXA) and peripheral quantitative computerized tomography (pQCT). Biomechanical properties were determined using three-point bending tests. Vertebral bone samples were prepared for quantitative polarized light microscopy and digital densitometry of proteoglycans. The concentration of total collagen and collagen cross-links were analyzed using high-performance liquid chromatograpy (HPLC). The average daily running distance was shorter for the HZK mice between the age of 4 and 15 months as compared with normal runners (P < 0.05). The ultimate breaking force was 14.8% and 23.6% (9 vs. 15 months) lower in HZK-runners than in wild-type runners. BMD of the femur was 6.1% lower in HZK-runners at the age of 9 months (P < 0.05). Physical activity increased cortical BMD in wild-type runners but not in the HZK runners at the age of 9 months. The collagen network of the HZK mice was less organized. There were only minor changes in BMD and mechanical and structural properties between sedentary HZK mice and their wild-type controls. Increased physical activity induced significantly lower bone density, mechanical properties, and organization of collagen fibers in male HZK mice. However, there were no major differences in biomechanical parameters between sedentary HZK and wild-type male mice. This suggests an important guiding role of collagen type II in bone remodelling and maturation.

Animals↗
PubMed2004

Calcaneal ultrasound predicts early postmenopausal fractures as well as axial BMD. A prospective study of 422 women.

Low calcaneal ultrasound measurement (quantitative ultrasound, QUS) has been shown to predict fractures in elderly women. However, only a few studies have examined its ability to predict perimenopausal and early postmenopausal fractures. We conducted a prospective population-based cohort study to assess the capability of QUS as compared to axial BMD measurement to predict early postmenopausal fractures at that age. Four hundred and twenty-two women (mean age 59.6, range 53.7-65.3) from the Kuopio Osteoporosis Risk Factor and Prevention Study (OSTPRE) were randomly chosen to undergo a calcaneal ultrasound measurement. In all, 9.4% of these women were premenopausal at the time of measurement. Thirty-two follow-up fractures were reported during the mean follow-up of 2.6 years (SD 0.7). These were validated with patient record perusal. Broadband ultrasound attenuation (BUA), speed of sound (SOS) and stiffness index (SI) were significantly lower among women with than without fracture ( P-values 0.028, 0.001 and 0.001, respectively). Mean T-score adapted from SI was -1.5 (95% CI -1.7 to -1.2) for fracture group and -1.0 (95% CI -1.1 to -0.9) for the non-fracture group. All QUS measurements predicted fractures even after adjusting for age, weight, height, previous fracture history, femoral neck BMD and use of hormone replacement therapy according to Cox regression. The adjusted hazard ratios (HR, 95% confidence interval) of a follow-up fracture for a 1 SD decrease were 1.80 (1.27-2.56), 1.72 (1.21-2.45) and 1.43 (1.01-2.03) for SOS, SI and BUA, respectively. Similarly, the adjusted HR for a 1 SD decrease of spinal BMD was 1.27 (0.85-1.94) and for that of femoral neck BMD 1.14 (0.78-1.70). In receiver operator analyses, the area under the curve (AUC) was greatest for QUS measurements: SOS (AUC=0.68), stiffness (AUC=0.67), BUA (AUC=0.62) and least for lumbar BMD (AUC=0.56), while and femoral neck BMD (AUC=0.59). The difference between AUCs was statistically significant between SI and lumbar BMD ( P=0.02, Duncan's P=0.07). We conclude that low calcaneal QUS predicts early postmenopausal fractures as well as or even better than axial BMD.

Bone Density↗
PubMed2001

Continuous mean arterial pressure measurement in the fingers: the influence of local arm cooling.

Two different methods were studied for non-invasive beat-to-beat finger mean arterial pressure (MAP) measurement in 14 healthy volunteers during local arm cooling to 17 degrees C. Fingertip skin blood flow was recorded by a laser Doppler instrument. The difference between the oscillometric beat-to-beat blood pressure measurement device (UT9201) and volume clamp monitor (Finapres) before cooling was -1.5+/-1.1 mmHg, and, although statistically significant, (p< 0.01), this difference cannot be considered clinically meaningful. The results obtained using the two devices during arm cooling showed a systematic disagreement in the continuously recorded MAP. After a 30s period of cooling, the group-averaged difference of UT9201 minus Finapres, calculated as change from the baseline, reached (mean +/- SD) 8.8+/-6.3 mmHg (statistically significant, p< 0.01).

Adult↗
PubMed2001

Leisure-time physical activity and rate of bone loss among peri- and postmenopausal women: a longitudinal study.

We examined the association between continuous leisure-time physical activity and the change in bone mineral density (BMD) and bone mineral content (BMC) in a population-based random sample of 1873 peri- and postmenopausal women. Leisure-time physical activities were registered with self-administered questionnaires in 1989 and 1994, and with an assisted questionnaire in 1995-1997. BMD and BMC were measured from lumbar vertebrae L2-4 and left femoral neck using dual-energy X-ray absorptiometry (DXA) in 1989-1991 and 1994-1997. During the average 5.6 year follow-up, annual loss of lumbar BMC was 124 mg (311 vs. 435 mg, p = 0.036) and annual loss of lumbar BMD was 1.22 mg/cm(2) (4.15 vs. 5.37 mg/cm(2), p = 0.21) smaller among women with regular (at least 1 h each week) weight-bearing leisure-time exercise compared with sedentary women. The advantage was even larger in women with walking or jogging as their only regular weight-bearing leisure-time exercise; that is, their annual loss of lumbar BMC was 180 mg (272 vs. 452 mg, p = 0.022), and annual loss of lumbar BMD was 2.78 mg/cm(2) (2.96 vs. 5.74 mg/cm(2), p = 0.029) smaller than in sedentary women. Continuous leisure-time physical activity did not have any association with loss of BMC or BMD in the femoral neck Physical activity during 12 months before the last bone densitometry was not associated with loss of BMC or BMD at any site. Our results suggest that regular weight-bearing exercise diminishes lumbar bone loss, but might be ineffective in the prevention of femoral osteoporosis among peri- and early postmenopausal women.

Bone Density↗
PubMed2001

Evaluation of VOC measurments in the EXPOLIS study. Air Pollution Exposure Distributions within Adult Urban Urban Populations in Europe.

Personal exposures and microenvironment concentrations of 30 target VOCs were measured for 401 participants living in five European cities as a part of the EXPOLIS (Air Pollution Exposure Distributions within Adult Urban Populations in Europe) study. Measurements in Basel used an active charcoal (Carbotech) adsorbent as opposed to the Tenax TA used in the other study centres. In addition, within each centre, personal and microenvironment VOC sampling required different sampling pumps and, because of different sampling durations, different sampling flow rates. Thus, careful testing of the sampling and analysis procedures was required to ensure accuracy and comparability of collected data. Monitor comparison tests using Tenax TA showed a mean VOC concentration ratio of 0.95 between the personal and microenvironment monitors. The LODs for the target VOCs using Tenax TA ranged from 0.7 to 5.2 microg m(-3). The LODs for the 14 target compounds quantifiable using Carbotech ranged from 0.9 to 3.2 microg m(-3). Tenax TA field blanks showed no remarkable contamination with the target VOCs, except benzaldehyde, a known artefact with this adsorbent. Thus, the diffusion barrier system used prevented contamination of Tenax TA samples by passive diffusion during non-sampling periods. Duplicate and parallel evaluations of the Tenax TA and Carbotech showed an average difference of < 17% in VOC concentrations within the sampling methods, but a systematic difference between the methods (Tenax TA: Carbotech concentration ratio = 1.18-2.36). These field evaluations and quality assurance tests showed that interpretation and comparison of the results in any VOC monitoring exercise should be done on a compound by compound basis. It is also apparent that carefully planned and realised QA and QC (QA/QC) procedures are needed in multi-centre studies, where a common sampling method and laboratory analysis technique are not used, to strengthen and simplify the interpretation of observed VOC levels between participating centres.

Air Pollution↗
PubMed2001

Personal exposure levels and microenvironmental concentrations of formaldehyde and acetaldehyde in the Helsinki metropolitan area, Finland.

Personal 48-hr exposures to formaldehyde and acetaldehyde of 15 randomly selected participants were measured during the summer/autumn of 1997 using Sep-Pak DNPH-Silica cartridges as a part of the EXPOLIS study in Helsinki, Finland. In addition to personal exposures, simultaneous measurements of microenvironmental concentrations were conducted at each participant's residence (indoor and outdoor) and workplace. Mean personal exposure levels were 21.4 ppb for formaldehyde and 7.9 ppb for acetaldehyde. Personal exposures were systematically lower than indoor residential concentrations for both compounds, and ambient air concentrations were lower than both indoor residential concentrations and personal exposure levels. Mean workplace concentrations of both compounds were lower than mean indoor residential concentrations. Correlation between personal exposures and indoor residential concentrations was statistically significant for both compounds. This indicated that indoor residential concentrations of formaldehyde and acetaldehyde are a better estimate of personal exposures than are concentrations in ambient air. In addition, a time-weighted exposure model did not improve the estimation of personal exposures above that obtained using indoor residential concentrations as a surrogate for personal exposures. Correlation between formaldehyde and acetaldehyde was statistically significant in outdoor microenvironments, suggesting that both compounds have similar sources and sinks in ambient urban air.

Acetaldehyde↗
PubMed2000

Bone loss around failed femoral implant measured by dual-energy X-ray absorptiometry.

Periprosthetic bone mineral density (BMD) and its changes after primary total hip arthroplasty (THA) have been studied extensively, but quantitative data on BMD around loosened prostheses are still lacking. In this study, using dual-energy X-ray absorptiometry (DXA), we determined periprosthetic BMD in 19 patients with failed primary THA. There was a decrease in BMD (8. 8%-25.5%) in every Gruen zone as compared with the patient's non-operated (control) side. Although the bone loss was most significant in the proximal femur, as in primary THA, the pattern of bone loss around the failed THA differred from the typical remodeling seen after successful THA. We suggest that quantitation of bone mass around the failed femoral stem is possible. Remarkable generalized bone loss around the stem is associated with a loosened prosthesis.

Absorptiometry, Photon↗
PubMed2000

Incomplete restoration of immobilization induced softening of young beagle knee articular cartilage after 50-week remobilization.

The aim of this study was to characterize the biomechanical and structural changes in canine knee cartilage after an initial 11-week immobilization and subsequent remobilization period of 50 weeks. Cartilage from the immobilized and remobilized knee was compared with the tissue from age-matched control animals. Compressive stiffness, in the form of instant shear modulus (ISM) and equilibrium shear modulus (ESM) of articular cartilage, was investigated using an in situ indentation creep technique. The local variations in cartilage of glycosaminoglycan (GAG) concentration were measured with a microspectrophotometer after safranin O staining of histological sections. Using a computer-based quantitative polarized light microscopy method, collagen-related optical retardation, gamma, of cartilage zones were performed to investigate the collagen network of cartilage. Macroscopically, cartilage surfaces of the knee joint remained intact both after immobilization and remobilization periods. Immobilization caused significant softening of the lateral femoral and tibial cartilages, as expressed by ESM (up to 30%, p < 0.05). Remobilization restored the biomechanical properties of cartilage in the lateral condyle of tibia, but in the lateral condyle of femur ESM remained 15% below the control level (p = 0.05). The instant shear modulus was not changed either after immobilization or remobilization. The GAG content of the cartilage was slightly decreased after immobilization, especially in the superficial zone of cartilage, but the change was not statistically significant. After remobilization the intensity of safranin O content rose to control level. Neither immobilization nor remobilization had any effect on the gamma value of collagen fibril network either in the superficial or the deep zone at any of the test points. The changes of ESM were positively correlated with the alterations in GAG content of the superficial and deep zones after immobilization and remobilization. This confirms the key role of protoglycans in the regulation of the equilibrium stiffness of articular cartilage. As a conclusion, immobilization of the joint of a young individual may cause long-term, if not permanent, alterations of cartilage biomechanical properties. This may predispose joint to degenerative changes later in life.

Age Factors↗
PubMed1999

Osteoporosis in adult patients with celiac disease.

We investigated the bone mineral density (BMD) and prevalence of osteopenia and osteoporosis in adult celiac patients with varying disease states. In this cross-sectional study the data on the severity of celiac disease and BMD were collected from 77 celiac patients (28 newly diagnosed and 49 previously diagnosed celiac patients), and BMD results were compared with those of 157 control subjects matched for age, gender, and menopausal status. The celiac patients had significantly lower BMD than the control subjects at the lumbar spine (-6%) and femoral neck (-5%). The mean BMD did not differ significantly among celiac patients classified by severity of disease. Based on Z scores, 35% of the celiac patients and 17% of the control subjects had low BMDs for age at the lumbar spine (p = 0.005), whereas 31% of celiac patients and 16% of control subjects had Z scores of < or =-1 at the femoral neck (p = 0.01). Altogether, 26% of all celiac patients, but only 5% of control subjects, were classified as having osteoporosis (T score < or =-2.5 SD) at the lumbar spine (p = 0.03), whereas osteoporosis was rare at the femoral neck in both groups (3% vs. 1%, p = 1.00). Prevalence of osteopenia and osteoporosis was highest in newly diagnosed celiac patients and in patients with disease not in remission. A low 25-(OH)D vitamin concentration was a typical biochemical abnormality in our patients (64% of men and 71% of women). The main associated variables of low BMD were age (men), low serum vitamin D level, low body weight, and postmenopausal status (women). The present study suggests that celiac disease constitutes a risk factor for osteoporosis. This finding applies particularly to untreated and poorly treated patients.

Absorptiometry, Photon↗
PubMed1999

Bone recovery after a gluten-free diet: a 5-year follow-up study.

The purpose of our study was to investigate the recovery of bone disease in celiac patients during 5 years of a gluten-free diet. The study group consisted of 28 newly diagnosed celiac patients (9 men, 19 women) recruited between 1990 and 1991. Six patients withdrew from the 5-year follow-up. Compliance with the gluten-free diet was good: 96% at 1 year and 82% at 5 years. During the follow-up period, the body mass index increased significantly (8%). Both in men and women, bone mineral density (BMD) values determined by dual X-ray absorptiometry (DXA) increased at the lumbar spine (2%), the femoral neck (1%), the trochanter (6%), and the Wards' area (3%) during the follow-up. The increase in BMD was found already during the first year of follow-up. After 1 year, BMD increased or remained the same in 69% of the patients at the lumbar spine and in 67% of the patients at the femoral neck, 89% of patients at the throchanter, and 67% of patients at the Wards' area. During the 5-year follow-up, these figures were 52%, 46%, 68%, and 59%, respectively. At the baseline, 19 out of 28 patients, after 1 year, 14 out of 26 patients, and after 5 years, 2 out of 26 patients had low serum 25(OH)D vitamin values (p = 0.0001). A high serum parathormone value was noticed in 6 out of 25 patients at the baseline, but after 1 year, 5 of them showed normalized values (p = 0.03). According to our results, bone disease in celiac patients is cured in most patients during 5 years on a gluten-free diet. The improvement in BMD mostly occurred already within the first year after the establishment of a gluten-free diet.

Absorptiometry, Photon↗
PubMed1999

Prevention of femoral and lumbar bone loss with hormone replacement therapy and vitamin D3 in early postmenopausal women: a population-based 5-year randomized trial.

The long term effects of hormone replacement therapy (HRT) and vitamin D3 (Vit D) on bone mineral density (BMD) were studied. A total of 464 nonosteoporotic early postmenopausal women from the Kuopio Osteoporosis Study (n = 13100) were randomized to four groups: 1) HRT (sequential combination of 2 mg estradiol valerate and 1 mg cyproterone acetate, 2) Vit D3 (300 and 100 IU/day during the fifth year), 3) HRT and Vit D combined, and 4) placebo. Lumbar (L2-L4) and femoral neck BMD were determined by dual x-ray absorptiometry (DXA) at baseline and after 2.5 and 5 yr of treatment. Intention to treat analysis (n = 464) showed that after 5 yr, lumbar BMD remained unchanged in the HRT and HRT plus Vit D groups [+0.2% (P = 0.658) and +0.9% (P = 0.117), respectively], whereas lumbar BMD decreased by 4.6% in the Vit D group and by 4.5% in the placebo group (P < 0.001 in both). The loss of femoral neck BMD was less in the HRT (-1.4%; P = 0.005) and HRT plus Vit D (-1.3%; P = 0.003) groups than in the Vit D and placebo groups (-4.3%; P < 0.001 in both). Among those 370 women who complied with the 5-yr treatment, the effect was more pronounced: lumbar BMD had increased by 1.5% in the HRT (P = 0.009) and by 1.8% in the HRT plus Vit D group (P = 0.005), with a plateau after 2.5 yr, whereas lumbar BMD had decreased in both the Vit D and placebo groups (4.6% and 4.7%; P < 0.001, respectively). Femoral neck BMD decreased again less in the HRT (-0.4%) and HRT plus Vit D (-0.6%) groups than in the Vit D and placebo groups (-4.4% in both). This study confirms the positive long term effect of HRT on BMD also seen in intention to treat analysis. The data suggest that low dose vitamin D3 supplementation does not prevent bone loss in healthy, nonosteoporotic, early postmenopausal women, and it confers no benefit additional to that of HRT alone.

Cholecalciferol↗
PubMed1998

Does vitamin D strengthen the increase in femoral neck BMD in osteoporotic women treated with estrogen?

The long-term effects on bone of estrogen therapy (HRT) combined with vitamin D3 supplementation were evaluated and compared with the effects of HRT without vitamin D3 supplementation in a 4-year prospective, partly randomized study among 60 osteoporotic women (mean age 55.4 years; range 49.7-59.4 years). The women studied were a subgroup of the population-based Kuopio Osteoporosis Risk Factor and Prevention Study (OSTPRE) (n = 13,100). The bone mineral densities (BMD) of the lumbar spine and femoral neck were determined by dual-energy X-ray absorptiometry (DXA) in 3236 perimenopausal women. Those 106 women with baseline BMD more than 2 SDs less than the mean value in this population, either at the lumbar spine (BMD < 0.826 g/cm2) and/or femoral neck (BMD < 0.684 g/cm2), were offered treatment for osteoporosis. After exclusions, 60 women were included in the analyses. Group allocation was: HRT (estradiol valerate (2 mg) plus cyproterone acetage, 1 mg, sequentially: ClimenR) (n = 21); HRT + Vit D: Climen + vitamin D3 (cholecalciferol, 300 IU/day, no intake during June-August) (n = 23); controls: 16 women who refused all treatment served as a non-randomized control group. In the HRT group, the highly significant increase in lumbar BMD was 5.4%, 5.3%, 4.7% and 4.0% after 1, 2, 3 and 4 years of treatment, respectively, all compared with the baseline values and with the control group. The increase in femoral neck BMD was statistically insignificant (1.4%, 2.2%, 1.9% and 2.1%, respectively; p > 0.05). In the HRT + Vit D group, the lumbar BMD increased by 3.7%, 4.9%, 4.9% and 4.9% (p < 0.001), whereas the 5.8% increase in femoral neck BMD reached significance at 4 years (p < 0.01) when compared with the control group as well as with the baseline values. However, there were no statistically significant differences in lumbar or femoral BMD changes between the two HRT groups. In conclusion, estrogen can substantially increase lumbar bone mass in patients with postmenopausal osteoporosis. In addition, the combination of HRT and vitamin D3 may increase femoral neck BMD in osteoporotic women more than estrogen alone.

Androgen Antagonists↗
PubMed1998

Bone density at the proximal femur after total hip arthroplasty.

Recent developments in dual xray absorptiometry have made it possible to quantify bone mineral density changes adjacent to total hip arthroplasty. Even small changes in local bone mass that are not visible with conventional radiographs can be detected using dual xray absorptiometry. Commonly there is a loss of 10% to 45% of the periprosthetic bone mass during the first years after total hip arthroplasty. Recent studies have suggested that this bone loss is not necessarily progressive and some degree of restoration of bone density around implants may occur. Current data suggest that there is active bone remodeling in the proximal femur in response to prosthetic implantation. Such response differs between different stem designs and type of fixation.

Absorptiometry, Photon↗
PubMed1995

Indentation instrument for the measurement of cartilage stiffness under arthroscopic control.

Changes in the biomechanical properties of articular cartilage are one of the first signs of the tissue degeneration. We have developed a small size indentation instrument for the quantification of cartilage stiffness under arthroscopic control. During measurement, the indenter imposes a constant deformation on the cartilage and the maximal indenter force, by which the cartilage resists the deformation, is used as a measure for cartilage stiffness. The instrument has been tested in laboratory conditions with elastomer and cadaver knee joint cartilage samples. A linear relationship was found between indenter force and elastomer stiffness (r = 0.990, n = 14) as well as between indenter force and cartilage shear modulus obtained by a reference device (r = 0.879, n = 22). Also, the correlation between two repeated measurements at the measurement sites, used to evaluate the reproducibility, was linear (r = 0.953, n = 16). Quantitative detection of cartilage stiffness is possible with the instrument.

Arthroscopes↗
PubMed1995

Ultrasound attenuation of the calcaneus in normal subjects and in patients with wrist fracture.

We determined broadband ultrasound attenuation (BUA) of the calcaneus, and bone mineral density (BMD) of the spine, proximal femur and radius in 137 healthy subjects (79 women and 58 men) and in 56 women with Colles' fracture. The repeated measurements on 9 healthy subjects indicated a short-term reproducibility (coefficient of variation) of 4 percent for BUA. There was a small (7 percent) but significant difference in BUA between normal men and women. The age-dependence in normal subjects was weak. When all the study subjects were pooled, modest correlations between BUA of the calcaneus and BMD at all measured skeletal sites were found (rs values 0.3-0.4). However, it was not possible to make an accurate prediction of the axial BMD, using BUA. BUA values were 13 percent lower in the wrist fracture patients than in the age-matched normals. In general, BUA could discriminate the fracture patients from normals as effectively as BMD. As suggested by the physical theory of ultrasound attenuation, our results support the idea that BUA reflects not only the bone density but also other factors related to the structural properties of bone.

Absorptiometry, Photon↗
PubMed1994

Articular cartilage thickness and glycosaminoglycan distribution in the young canine knee joint after remobilization of the immobilized limb.

The recovery of articular cartilage from atrophy induced by joint immobilization was investigated in immature dogs. In a previous study, we showed that 11 weeks of immobilization of the knee (stifle) joint of young dogs reduced the concentration of articular cartilage glycosaminoglycans (GAGs) by 13-47%. In the present study, right hindlimbs from six female beagles were immobilized for 11 weeks, as in the previous study, and then were remobilized for 15 weeks. Cartilage from the knee joint was compared with cartilage from nonimmobilized knees of eight age-matched control beagles. Histological samples taken from 11 different locations of the knee joint were stained with safranin O, and microspectrophotometry was used to demonstrate distribution of GAGs in the tissue. After remobilization, GAG concentration was restored in the patellofemoral region and tibial condyles. On the summits of the femoral condyles, and especially at the periphery of the femoral condyles, GAG concentration remained 8-26% less than the control values. On the summits, the thickness of the uncalcified cartilage was as much as 15% less than in the age-matched controls. Consequently, the changes induced by unloading were reversible to a great extent, but a full restoration of articular cartilage was not obtained at all sites of the knee joint within the 15 weeks of remobilization. Immobilization of the skeletally immature joint therefore may affect the development of articular cartilage in such a way that very slow recovery or permanent alterations are induced.

Animals↗
PubMed1994

Softening of the lateral condyle articular cartilage in the canine knee joint after long distance (up to 40 km/day) running training lasting one year.

The effects of long distance running training (up to 40km/day) on the biomechanical properties of young canine articular cartilage were investigated using in situ indentation creep technique. The stiffness of articular cartilage was determined in the form of instantaneous and equilibrium shear moduli. The rate of cartilage deformation was also computed. Microspectrophotometric and polarized light microscopic analyses were made for determination of local glycosaminoglycan content and collagen organization, respectively. During a period of one year, the runner dogs (n = 10) underwent a gradually increased treadmill exercise up to 40 km/day, while the littermate control dogs (n = 10) lived normally in their cages. The equilibrium shear modulus of articular cartilage decreased significantly by 12 to 14% (p < 0.05) in the lateral, but not in the medial, condyles of femur and tibia. In the lateral condyles of the runner dogs, the deformation rate of cartilage increased by 16% (p < 0.05). Consequently, the articular cartilage response to running training was site-dependent. The simultaneous changes of the equilibrium shear modulus or the retardation time spectrum and the glycosaminoglycan content confirm the key role of proteoglycans in modulating the cartilage equilibrium stiffness and creep rate. The changes in the instant shear modulus appeared to be predominantly related to the alterations in the organization of the superficial collagen network. Although the running training did not create cartilage damage, we assume that the softening of the cartilage may with time jeopardize the ability of articular cartilage to maintain its normal structural and functional properties.

Animals↗