Biomedical subjects

M Järvinen

Publications and source records attributed to M Järvinen.

At least 19 recordsLinked to original sources

PubMed2006

Knee injuries in leisure-time physical activities: a prospective one-year follow-up of a Finnish population cohort.

This prospective one-year follow-up study compared the risks of knee injuries in various commuting and lifestyle activities as well as in recreational and competitive sports in a 15 to 74-year-old Finnish population cohort. A cohort of 3657 persons was randomly selected from the nationwide population register of Finland. Ninety-two percent of them accepted to participate (n = 3363). The subjects were interviewed by telephone three times during the one-year follow-up. The recorded data included all physical activities that lasted 15 minutes or more, and all injuries that were sustained during these activities. Fifteen percent (n = 321) of all reported injuries affected the knee. The individual risk of knee injury per 1000 exposure hours was low in commuting activities (cycling, walking), 0.06 (95 % CI 0.04 to 0.09) and in lifestyle activities (gardening, hunting, fishing, home repair etc.), 0.04 (0.03 - 0.06). In recreational and competitive sports, the knee injury risk was almost ten times higher, 0.44 (0.39 - 0.50). For commuting activities (p = 0.046) and for recreational and competitive sports (p < 0.001), there was a decreasing injury rate with age. In lifestyle activities (p = 0.038), in turn, there was an increasing trend of injuries with aging. In commuting activities (hazard ratio, HR 5.99, 95 % CI 1.40 to 25.6), the risk of knee injury was significantly higher in women than in men. In conclusion, the knee injury risk per exposure hours is almost ten times lower in commuting and lifestyle activities compared to recreational and competitive sports. The knee injury risk is especially high in the age group of 15 to 25 years, especially in various team sports and ball games. At population level, however, widely practiced low-to-moderate intensity activities with relatively low injury risk per exposure hours produce a large absolute number of knee injuries.

Adolescent↗

PubMed2004

Active living and injury risk.

The purpose of this study was to get reliable insight into injury risk in various commuting and lifestyle activities, as well as recreational and competitive sports. A cohort of 3 657 persons was randomly selected from the 15- to 74-year-old Finnish population. Ninety-two percent (n = 3 363) of the subjects accepted to participate the one-year follow-up, record all their physical activities that lasted 15 min or more, and register all acute and overuse injuries that occurred during these activities. To collect the information, the study subjects were interviewed by phone by the trained personnel of the Statistics Finland three times in four-month intervals. The individual injury risk per exposure time was relatively low, ranging from 0.19 to 1.5 per 1 000 hours of participation, in commuting and lifestyle activities including walking and cycling to work, gardening, home repair, hunting and fishing, and, in sports such as golf, dancing, swimming, walking, and rowing. The risk was clearly higher in squash, orienteering, and contact and team sports, such as judo, wrestling, karate, rinkball, floorball, basketball, soccer, ice hockey, volleyball, and Finnish baseball ranging from 6.6 to 18.3 per 1 000 hours of participation. However, the highest absolute number of injuries occurred in low-risk activities, such as gardening, walking, home-repair, and cycling, because they are performed so often. In conclusion, individual injury risk per exposure hours is relatively low in commuting and lifestyle activities compared to many recreational and competitive sports. However, at a population level, these low-to-moderate intensity activities are widely practised producing a rather high absolute number of injuries, and thus, preventive efforts are needed in these activities, too.

Activities of Daily Living↗

PubMed2003

Early embryonic development and in vitro culture of in vivo produced embryos in the farmed European polecat (Mustela putorius).

Early embryonic development and in vitro culture of in vivo produced embryos in the farmed European polecat (Mustela putorius) was investigated as a part of an ex situ conservation program of the endangered European mink (Mustela lutreola), using the European polecat as a model species. The oestrus cycles of 34 yearling polecat females were monitored by visual examination of the vulval swelling and, to induce ovulation, the females were mated once daily on two consecutive days. Sixteen yearling males were used for mating. The females were humanely killed 3-14 days after the first mating and the uteri and oviducts were collected for embryo recovery. Uterine and oviductal flushings yielded a total number of 295 embryos, representing developmental stages from the 1-cell stage to large expanded and hatched blastocysts. On Day 3 after the first mating, only 1-16-cell stage embryos were recovered. Between Days 4 and 6 after the first mating, 1-16-cell stage embryos and morulae were found. The first blastocysts were recovered on Day 7 after the first mating. The first implanted blastocysts were detected on Day 11 after the first mating. A total number of 85 embryos were in vitro cultured after recovery. Blastocyst production rates for in vitro cultured 1-16-cell stage embryos and for morulae/compact morulae were 68 and 84%, respectively. For all cultured embryos, the hatching rate was 15%. The in vitro culture requirements for the preimplantation embryos of the farmed European polecat remain to be determined before further utilization of the technique.

Animals↗

PubMed2003

Increased volumetric wear of polyethylene liners with more than 3 years of shelf-life time.

We analyzed 20 retrieved gamma-sterilized polyethylene liners (Biomet Hexloc). The long-term durability varied significantly depending on shelf-life time before implantation. Liners with a shelf-life time of 3 years or more evinced significantly ( P 0.002) higher volumetric wear than those with a shelf life time less than 3 years. Infrared spectroscopy and scanning calorimetry showed that all explanted implants underwent substantial in vivo oxidation and crystallization. The oxidative ageing of polyethylene renders the polyethylene liner susceptible to severe wear. Scanning electron microscopy of the bearing surface of the liner revealed abrasive wear as a dominant mechanism. Moreover, poor acetabular design produces excessively thin liners, substandard locking mechanism, and backside wear of the liner. The primary reason for severe wear in the Hexloc liner was poor modular design and oxidative degradation of the polyethylene.

Adult↗

PubMed2003

Estrogen deposits extra mineral into bones of female rats in puberty, but simultaneously seems to suppress the responsiveness of female skeleton to mechanical loading.

To first test the possible effect of gender on the responsiveness of growing rat skeleton to mechanical loading, 5-week-old littermates of 25 male and 25 female rats were subjected to either free-cage activity or treadmill training for a period of 14 weeks (experiment 1). Using peripheral quantitative computed tomography (pQCT) and mechanical testing of the femoral neck, we observed female rats exhibiting a clearly lower responsiveness to external loading than male rats (+3.0% vs +25% in cross-sectional area (CSA), +4.2% vs +27% in the bone mineral content (BMC), -0.6% vs +10% in volumetric bone mineral density (BMD), and +4.7% vs +28% in fracture strength (F(max)) of the femoral neck). Also, relative to the mechanical demands placed on the skeleton, the bones of the young female rats were considerably denser (>50%) than those of the males. In the subsequent experiment 2, we repeated the above-noted first experiment with 33-week-old rats and observed virtually identical exercise-induced benefits (+2.1% vs +10% in CSA, +3.4% vs +18% in BMC, +2.5% vs +23% in BMD, and -1.1% vs +27% in F(max) in females vs males, respectively) and the growth/puberty-related condensation of mineral into female bones. Finally, in experiment 3, 60 littermates of 3-week-old female rats were first subjected to sham operation or ovariectomy and then further randomized to exercise or control groups, respectively, to study whether the condensation of mineral into female bones and their lower responsiveness to loading were attributable to the effects of estrogen. At the end of the 16-week intervention, our pQCT and mechanical testing analysis showed not only the anticipated effect of reduced bone density in the ovariectomized rats ( approximately -20%) but also the hypothesized better responsiveness to mechanical loading in these estrogen-depleted rats (-3.5% vs +9.1% in CSA, -0.4% vs +12% in BMC, +4.4% vs +9.6% in BMD, and -4.2% vs +16% in F(max) in SHAM vs OVX, respectively). In conclusion, the results of our series of three experiments suggest that as such estrogen seems to have very little primary effect on the sensitivity of female bone to respond to external loading, but rather deposits extra stock of mineral into female bones in puberty. This estrogen-driven extra condensation of the female skeleton seems to persist into adulthood, simultaneously damping the responsiveness of the female skeleton to mechanical loading.

Animals↗

PubMed2003

Basic science and clinical studies coincide: active treatment approach is needed after a sports injury.

The basic response to injury at the tissue level is well known and consists of acute inflammatory phase, proliferative phase, and maturation and remodeling phase. Knowing these phases, the treatment and rehabilitation program of athletes' acute musculoskeletal injuries should use a short period of immobilization followed by controlled and progressive mobilization. Both experimental and clinical trials have given systematic and convincing evidence that this program is superior to immobilization - a good example where basic science and clinical studies do coincide - and therefore active approach is needed in the treatment of these injuries.

Animals↗

PubMed2002

Microbial toxicity tests and chemical analysis as monitoring parameters at composting of creosote-contaminated soil.

Traditionally, chemical analyses are used in the assessment of contaminated soil and in monitoring the efficiency of soil remediation processes. We investigated if chemical analysis could be supported and even partly replaced by biological toxicity tests. In two case studies creosote-contaminated soil was composted outdoors in 5- and 100-m3 windrows. Degradation of polyaromatic hydrocarbons (PAHs) was followed by chemical analysis and toxicity tests. Polyaromatic hydrocarbons were quantified and identified by HPLC. Because the soil was also contaminated by copper-, chromium-, and arsenic-containing fungicides, these elements were analyzed by atomic absorption spectrometry. The toxicity of soil samples was assessed by a soil-contact modification of the luminescent bacteria (Vibrio fischeri) test and in the other case also by enzyme synthesis inhibition (Toxi-ChromoPad test, Escherichia coli). The toxicity of soil water extracts was measured by the standard luminescent bacteria (V. fischeri) test and bacterial (Pseudomonas putida) growth inhibition test. After the first 4 months of the composting period the total amount of PAHs was reduced in all windrows, and in particular, the loss of two- and some three-ring compounds was high, almost 90%. Toxicity decreased concurrently with the decrease in PAH concentration during composting, but after 4 months, one of the piles inoculated with mycobacteria and containing more three- and four-ring compounds was found to be more toxic than at the beginning. After the next summer, total PAH content was further reduced but some four-ring or heavier compounds were demonstrated to be poorly degraded. The toxicity was also reduced to the same level as in the control pile. The total PAH content and the toxicity were both reduced significantly during 5 months of composting.

Biodegradation, Environmental↗

PubMed2002

[Pathophysiology of overuse tendon injury].

Overuse tendon injury is one of the most common injuries in sports. The etiology as well as the pathophysiological mechanisms leading to tendinopathy are of crucial medical importance. At the moment intrinsic and extrinsic factors are assumed as mechanisms of overuse tendon injury. Except for the acute, extrinsic trauma, the chronic overuse tendon injury is a multifactorial process. There are many other factors, such as local hypoxia, less of nutrition, impaired metabolism and local inflammatory that may also contribute to the development of tissue damage. The exact interaction of these factors cannot be explained entirely at the moment. Further studies will be necessary in order to get more information.

Achilles Tendon↗

PubMed2002

Temporal coherence in water temperature and chemistry under the ice of boreal lakes (Finland).

Temporal coherence was assessed for 11 limnological variables--water temperature, oxygen, conductivity, alkalinity, pH, colour, calcium (Ca), iron, aluminium, total phosphorus and total nitrogen--between 28 boreal lakes in southern Finland for the winter ice-covered period. The lakes were mainly small (<0.2 km2) and brown-coloured, and located within a circle of 10-km radius. A mean Pearson correlation coefficient for all lake pairs and variables averaged 0.37. Temporal coherence of variables across lake pairs was highest for conductivity, Ca, water temperature and alkalinity. The lake pairs with a direct surface water channel connection had a higher coherence than the lake pairs not connected by a stream. The size of the lake or catchment area had little effect on the coherence between the lakes. Temporal coherence was not strongly related to the difference in water colour (dystrophy) between the lakes. However, between polyhumic lakes (colour > 100 g Pt m(-3)) the coherence was generally higher than between less coloured lakes. Year-to-year variation in limnological characteristics could be partly explained by the variation in local weather. In March, water temperature and chemistry were infrequently related to winter weather, rather they correlated with the weather conditions of the previous autumn, while the ambient late winter weather seemed to have a stronger influence on lake conditions in April. Temporal variation in some variables was related to the atmospheric pressure changes over the North Atlantic (the North Atlantic Oscillation, NAO). Our results suggest that the potential effects of climatic change on lakes can be generalised regionally for brown-coloured dystrophic lakes.

Aluminum↗

PubMed2002

Increasing number and incidence of low-trauma ankle fractures in elderly people: Finnish statistics during 1970-2000 and projections for the future.

To increase knowledge about recent trends in the number and incidence of various low-trauma injuries among elderly people, we selected, from the National Hospital Discharge Register, all patients > or =60 years of age who were admitted to hospitals in Finland (5 million population) for primary treatment of a first low-trauma ankle fracture during 1970-2000. In each year of the study, the age-adjusted and age-specific incidence of fracture was expressed as the number of patients per 100,000 persons. The predicted numbers and incidence rates of fractures until the year 2030 were calculated using a regression model. For the study period, the number and incidence of low-trauma ankle fractures in Finnish persons > or =60 years of age rose substantially: the total number of fractures increased from 369 in 1970 to 1545 in 2000, a 319% increase, and the crude incidence increased from 57 to 150, a 163% increase. The age-adjusted incidence of these fractures also rose in both women (from 66 in 1970 to 174 in 2000, a 164% increase) and men (from 38 in 1970 to 114 in 2000, a 200% increase). The regression model indicates that, if this trend continues, there will be about three times more low-trauma ankle fractures in Finland in the year 2030 than there was in 2000. In conclusion, the number of low-trauma ankle fractures in elderly Finns is rising rapidly at a rate that cannot be explained simply by demographic changes and, therefore, potentially effective preventive measures, such as prevention of slippings, trippings, and falls in elderly people, and use of ankle supports, should be urgently studied.

Aged↗

PubMed2002

Simple measurements in assessing muscle performance after an ACL reconstruction.

The purpose of this study was to evaluate the validity of the simple measurements of the muscle performance of the lower extremity, one legged hop testing for distance and the measurement of the circumference of the thigh 15 cm proximal to the joint line, by comparing them to the isokinetic strength testing 5 to 9 years after an ACL reconstruction with a bone-patellar tendon-bone (BTB) autograft. The measurements were performed on 86 patients on average 7 years after the surgery. The clinical evaluation was performed using the standard knee ligament evaluation form of the International Knee Documentation Committee (IKDC) and the Lysholm and the Marshall knee scores. At seven years, the isokinetic mean strength deficit of knee extension at the 60 degrees per second was 10 % in the operated limb as compared to the contralateral limb (NS). In the knee flexion, the differences were even smaller and statistically not significant either. The strength deficit of the knee extension at all knee angle velocities (p < 0.005), and flexion at 60 degrees per second (p < 0.05), correlated to the one legged hop testing, so that the patients with the greatest strength deficit also had the worst outcome in the one legged hop test. Also, the correlation between thigh atrophy and the deficit in the isokinetic strength test was significant in knee extension at all knee angle velocities (p < 0.001), and in knee flexion at 180 degrees per second (p < 0.005). In the final evaluation of the IKDC, 21 patients were rated as "normal", 51 as "nearly normal", 13 as "abnormal", and one as "severely abnormal". The mean of the Lysholm score was 83, classified as good, and that of Marshall score 43, classified as good. In conclusion, the one legged hop testing, as a functional muscle strength testing after an anterior cruciate ligament reconstruction, seems to correlate well with the isokinetic strength testing of the knee, especially in the knee extension. Because the hop testing can be easily performed and without extra equipment, we recommend its use for the evaluation of the functional muscle performance after an anterior cruciate ligament reconstruction. The measurement of the thigh atrophy is also easy to perform, and should be used beside the one legged hop testing, especially if the isokinetic strength testing is not available.

Analysis of Variance↗

PubMed2002

Surgical treatment for chronic Achilles tendinopathy: a prospective seven month follow up study.

OBJECTIVE: To prospectively assess the early results of surgical treatment of chronic Achilles tendinopathy. METHODS: This seven month prospective follow up study assessed the short term results of surgical treatment of chronic Achilles tendinopathy and compared the subjective and functional outcome of patients with Achilles tendinopathy without a local intratendinous lesion (group A) with that of similar patients with such a lesion (group B). Forty two of the initial 50 patients were examined before surgery and after the seven month follow up. Evaluation included an interview, subjective evaluation, clinical tests, and a performance test. RESULTS: At the follow up, physical activity was fully restored in 28 of the 42 patients (67%), and 35 patients (83%) were asymptomatic or had only mild pain during strenuous exercise. In clinical tests, significant improvements were observed in climbing up and down stairs and the rising on the toes test. Surgical treatment also seemed to be successful from the total test score, which was excellent or good in 35 patients, compared with before surgery when it was excellent or good in one patient only. Patients in group A fared better than those in group B, whether evaluated by recovery of physical activity after surgery (88% v 54%) or the complication rate (6% v 27%). CONCLUSIONS: Surgical treatment of chronic Achilles tendinopathy gives good and acceptable short term results. A lower complication rate and a trend to better recovery was observed in patients with peritendinous adhesions only than in those with peritendinous adhesions combined with an intratendinous lesion.

Achilles Tendon↗

PubMed2002

Bipolar hemiartroplasty in the treatment of hip fracture: are special centres necessary for the optimal outcome?

BACKGROUND AND AIMS: This study compares retrospectively clinical follow-up of 72 bipolar arthroplasties made either by specialist surgeons or residents. MATERIAL AND METHODS: 72 patients with a life-expectancy of more than three years were selected to have bipolar arthroplasty for the treatment of femoral collum fracture at Tampere University Hospital district during 1993-1995. The average age of the patients was 70 (47-92) years. All patients were followed at least 4 years for mortality as well as primary and late complications. A group of 49 (68%) patients could be followed more carefully by clinical examination, by questionaire or by phone. RESULTS: 20 (28%) patients died during the first three years after surgery and four (6%) patients were re-operated. The bare preoperative clinical estimation made by the senior consultant surgeon did not predict good enough the life expectancy of the patients. Four patients had been revised, all operated by a senior surgeon. There were no revisions among the patients operated by junior doctors. No statistical differences were found between the patients operated by junior or senior surgeons or between cemented and cementless prostheses in pain, walking distances, limping, getting in to a car, need of support or sitting in high or normal chair. CONCLUSIONS: The bipolar arthroplasty was found to give reproducible results also when residents take the responsibility of hip fracture treatment.

Aged↗

PubMed2001

Anterior cruciate ligament reconstruction in patients with or without accompanying injuries: A re-examination of subjects 5 to 9 years after reconstruction.

PURPOSE: The purpose of this study was to compare the clinical and radiologic results of an anterior cruciate ligament (ACL) reconstruction in patients with an isolated ACL tear and patients with an ACL tear and accompanying injuries. TYPE OF STUDY: A retrospective investigation. METHODS: Seventy-two patients who did not have previous knee surgery or surgery of the contralateral knee were re-examined 5 to 9 years after the primary ACL reconstruction. The clinical assessment was made using the International Knee Documentation Committee (IKDC) evaluation system, and the Lysholm and the Marshall knee scores. Also, radiographic evaluation and isokinetic strength testing were performed. There were 34 patients (25 men and 9 women) with an isolated ACL tear (group A), and 38 patients (23 men and 15 women) with an ACL tear and accompanying injuries (group B). The mean age was 29 years (SD 9; range, 15 to 49 years) in group A, and 34 years (SD 12; range, 15 to 61 years) in group B. Bone-patellar tendon-bone autograft with mini-arthrotomy technique and screw fixation was used in all patients. Postoperative rehabilitation was also similar in both groups. In group B, 10 medial and 12 lateral (partial or subtotal) arthroscopic meniscectomies were performed at the same time as the ACL reconstruction. Also, 18 of the 19 medial collateral ligament ruptures, the 2 lateral collateral ligament ruptures, and the 1 posterior cruciate ligament rupture were treated surgically at this operation. RESULTS: Subjectively (overall assessment, pain, swelling, and giving way of the knee) and objectively (range of motion, stability, crepitation, isokinetic strength testing, and radiological changes of the knee), the groups did not have any significant differences in the 5- to 9-year results. Also, the final evaluation results using the IKDC and the Lysholm and the Marshall knee scores were similar in both groups. However, there were significantly more subsequent knee surgeries in the injured knee in group B than in group A. CONCLUSIONS: Our results show no large differences between patients with an isolated ACL tear and those with an ACL tear with accompanying injuries 5 to 9 years after an ACL reconstruction with a bone-patellar tendon-bone autograft. Tibiofemoral osteoarthritis was quite rare, and this may be partly attributable to the fact that the ACL reconstructions were successful, so that all the knees were stable at the re-examination. However, the future will show the final outcome for the patients.

Adolescent↗

PubMed2001

Regulation of alpha7 integrin by mechanical stress during skeletal muscle regeneration.

The continuity of the tendon-myofibre-tendon units disrupted by shearing injury must be re-established during regeneration. We have previously demonstrated in freely moving rats that transected myofibres reinforce their lateral integrin-mediated adhesion, with the maximum around days 5-7. After day 14, most integrin molecules are redistributed to the newly formed myotendinous junctions, by which the ends of regenerating myofibres attach to the scar between the stumps. Here, we analyzed the effects of mechanical stress (free and forced mobilization vs. immobilization and denervation separately and in combination) on the expression of alpha7 integrin and merosin in regenerating myofibres using quantitative in situ hybridization and immunohistochemistry. In all groups, alpha7 integrin expression was upregulated at mRNA level, whereas increased protein accumulation in lateral sarcolemma occurred only in the mobilized groups. The accumulation of merosin was not affected by the stress level. The results demonstrate that active mechanical stress reinforces early lateral integrin-mediated adhesion; molecules may at the same time mediate signals from matrix to cells for adaptation to the altered biomechanical status.

Animals↗

PubMed2001

Graft placement after the anterior cruciate ligament reconstruction: a new method to evaluate the femoral and tibial placements of the graft.

In order to evaluate graft placement of the anterior cruciate ligament (ACL) reconstruction and its relationship to the clinical outcome of the patient, 100 patients were examined 7 years after an ACL reconstruction. Clinical assessment was performed using the standard knee ligament evaluation form of the International Knee Documentation Committee (IKDC), and the Lysholm and the Marshall knee scores. We developed a new evaluation method of graft placement after an ACL reconstruction, 'the sum score of the graft placement', which takes into account both the femoral and the tibial positions of the graft simultaneously, and our study showed that 'the sum score of the graft placement' has an association to clinical outcome of patients and that it can better explain the long-term osteoarthritic changes at the injured knee than the separate measurements of the femoral and tibial tunnel placements.

Adult↗

PubMed2001

Continuously rising problem of osteoporotic knee fractures in elderly women: nationwide statistics in Finland in 1970-1999 and predictions until the year 2030.

We assessed the current trends in the number and incidence of osteoporotic knee fractures in Finland by collecting data from the National Hospital Discharge Register for all patients > or =60 years of age who were admitted to Finnish hospitals in 1970-1999 for primary treatment of such fractures. The knee fracture was defined "osteoporotic" if it was caused by a low-energy trauma only; that is, a fall from standing height or less. We also predicted fracture development until the year 2030 by a regression model, which took into account the predicted changes in the fracture incidences and population at risk. The number and incidence (per 100,000 persons) of osteoporotic knee fractures in Finnish women aged > or =60 years clearly rose during the study period, from 218 (number) and 55 (incidence) in 1970 to 685 and 113 in 1999. Even after age adjustment, the incidence of women's fractures showed a clear increase, from 59 in 1970 to 105 in 1999. If this trend continues, there will be about 2.5 times more osteoporotic knee fractures in Finnish women in the year 2030 than there were in 1999. In Finnish men aged > or =60 years, the annual number of fractures and its changes were clearly smaller (77 in 1970 vs. 138 in 1999), and the fracture incidence did not show consistent trend changes over time (30 in 1970 vs. 34 in 1999). We conclude that in elderly Finnish women the number of osteoporotic knee fractures shows a rise with a rate that cannot be explained merely by demographic changes and, therefore, vigorous preventive measures are needed to control this development.

Age Distribution↗

PubMed2001

Effects of remobilization on rat femur are dose-dependent.

Seventy 9 to 11-week-old Sprague-Dawley male rats were divided into seven groups [baseline, 3-week, 11-week control groups; a group with a left limb immobilization for 3 weeks; and three groups with a similar immobilization and subsequent 8-week free (FR), low-intensity running (LR) or high-intensity running (HR) remobilization] to determine the site-specific effects of decreased mechanical loading and subsequent increased activity on rat femur. Bone mineral content of the proximal femur (PBMC), femoral midshaft (SBMC) and distal femur (DBMC) and the histomorphometry of the distal femur were used as outcome variables. The 3-week immobilization period resulted in significant bone loss in the proximal and distal ends of the immobilized left limb, the deficit being -5.9% in PBMC and -14.7% in DBMC. Immobilization also led to marked microarchitectural changes in the distal femur, the left-side deficit in trabecular bone volume (BV/TV) being -23.9%. After remobilization, there was a clear indication for dose-dependent response; i.e., immobilization-induced left-to-right side differences in BV/TV persisted in the FR animals (-23.8%), while these left limb deficits were significantly reduced in the LR group (-15.0%) and virtually absent in the HR group (-3.1%). The left limb deficit in PBMC was still significant in all groups after the 8-week period of remobilization [-9.6% in the FR group; -13.4% in the LR group; and -7.2% in the HR group]. The left-limb deficit in SBMC was significant in the HR11 group only (-7.2%), and, contrary to histomorphometric data, virtually absent in DBMC in all remobilization groups. As compared with the age-matched control data, the weight-adjusted BMCs of both limbs of the LR and HR groups were comparable or even higher (right limbs) than those of the controls. In conclusion, this study indicates that remobilization-induced bone recovery depends on the intensity of the remobilization so that during the 8-week period of remobilization, high-intensity running results in better recovery than low-intensity running, both of which are more efficient than free-cage activity only. Immobilization-induced changes in rat femur are also restored in a site-specific fashion, the most trabecular distal region of the femur showing more complete recovery than the more cortical proximal and midshaft regions.

Absorptiometry, Photon↗