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Motivated by some questions arising in the study of quasistatic growth in brittle fracture, we investigate the asymptotic behavior of the energy of the solution $u$ of a Neumann problem near a crack in dimension 2. We consider non smooth cracks $K$ that are merely closed and connected. At any point of density 1/2 in $K$, we show that the blow-up limit of $u$ is the usual "cracktip" function $\sqrt{r}\sin(\theta/2)$, with a well-defined coefficient (the "stress intensity factor" or SIF). The method relies on Bonnet's monotonicity formula \cite{b} together with $\Gamma$-convergence techniques.

The goal was to determine if calcium and vitamin D supplementation can reduce the incidence of stress fracture in female Naval recruits during basic training. The secondary goal was to examine the potential mechanisms for increasing bone adaptation to intense mechanical loading. We recruited 5201 females who were randomly assigned to calcium 2000 mg and vitamin D 800 I.U. per day or a control placebo group. The intervention and stress fracture monitoring continued through 8 weeks of basic training. We were not able to recruit the targeted number of subjects for the sub-study designed to determine changes in moment of inertia using peripheral quantitative computed tomography (pQCT) because the Great Lakes Command directed us to stop the study once we reached our target sample size (5201) for the primary study. For the substudy, we enrolled 148 (out of a target 560). SFx were ascertained when recruits reported to the Great Lakes clinic with symptoms. All SFx were confirmed with radiography or technetium scan according to the usual Navy protocol. A total of 309 subjects were diagnosed with a SFx resulting in an incidence of 5.9% per eight weeks. Using intention-to-treat analysis by including all enrolled subjects, we found that the calcium and vitamin D group had a 20% lower incidence of SFx than the control group (5.3% vs. 6.6%, respectively, P=0.0026 for Fisher s Exact test). The per protocol analysis, including only the 3700 recruits who completed the study, found a 21% lower incidence of fractures in the supplemented vs. the control group (6.8% vs. 8.6%, respectively, P=0.02 for Fisher s Exact test). Generalizing the findings to the population of 14,416 females who entered basic training at the Great Lakes during the 24 months of recruitment, calcium and vitamin D supplementation for the entire cohort would have prevented about 187 persons from fracturing. Such a decrease in SFx would be associated with a significant decrease in morbidity and financial costs.

The overall aim of this research is to gain insight into the etiology of tibial stress fractures. Three dimensional motion analysis data along with structural data will be collected from 400 subjects (200 at each site) over a 3-year period. 30 of the subjects will have sustained a tibial stress fracture prior to the study and the other 370 will have not. Subjects will be recruited primarily from track teams, running clubs, and physicians local to the University of Delaware and University of Massachusetts. Within this Annual Report, information concerning adherence to work objectives, preliminary results with respect to. the proposed hypotheses, and reportable outcomes are presented for the third year of the investigation. Overall, we have adhered to most work objectives and have proposed plans for rectifying any discrepancies. The preliminary analysis of the data demonstrates encouraging results and support of most hypotheses.

The overall aim of this research is to gain insight into the etiology of tibial stress fractures. Three dimensional motion analysis data along with structural data will be collected from 400 subjects (200 at each site) over a 3-year period. 30 of the subjects will have sustained a tibial stress fracture prior to the study and the other 370 will have not. Subjects will be recruited primarily from track teams, running clubs, and physicians local to the University of Delaware and University of Massachusetts. Within this Annual Report, information concerning adherence to work objectives, preliminary results with respect to. the proposed hypotheses, and reportable outcomes are presented for the third year of the investigation. Overall, we have adhered to most work objectives and have proposed plans for rectifying any discrepancies. The preliminary analysis of the data demonstrates encouraging results and support of most hypotheses.

The overall hypothesis driving this work was that an increase in microdamage activity during repeated loading of bone will signal the approaching fatigue fracture. The formation and propagation of microdamage, in the form of microcracks and diffuse damage, produces detectable acoustic emission events similar to the seismic motions of an earthquake. Therefore, impending fatigue fracture of bone can be detected by acoustic emissions. In order to test this hypothesis, fresh-frozen human tibias from males and females between the ages of 20 and 50 years old were acquired for use in testing procedure outlined below. Sections of the tibias were removed and machined into a proper geometry for fatigue tests. Microdamage formation with characteristic waveform properties was monitored through the use of piezoelectric acoustic emission transducers. The primary aim of this work was to investigate and quantify the damage events during the in vitro fatigue loading of cortical bone fatigue fracture model.

This first annual report reviews progress towards completing each of our three study tasks. Major accomplishments include IRB and HRPO approvals for all study protocols, hiring and training of staff at MGH, as well as the initiation of subject recruitment and enrollment. In study Task 1 we aim to determine the sex- and race-ethnicity-specific bone traits that may contribute to stress fracture risk in military recruits. We are ahead of enrollment projections, with 61 of 120 subjects enrolled to date (n= 40 White women, 14 White men, 6 Black women, 1 Black man). In study Task 2 we aim to quantify changes in bone structure and bone metabolism in recruits before and after Basic Combat Training (BCT). Enrollment (n=161) and data collection are complete, and data analysis is ongoing. Finally, for study Task 3 we aim to characterize recovery and predict bone-healing trajectories and develop return-to-duty guidelines. We hypothesize that changes in bone health during recovery from stress-fracture injury can be quantified and used to develop evidence-based RTD. Enrollment is underway, with 3 women with recent stress fracture enrolled.

The occurrence of stress fractures indicates a failure to maintain an adequate match between bones structure and their functional requirement. Stress fractures occur both in well-trained athletes pushins for the limits of their performance, and in poorly-trained people, particularly women, following an abrupt change or increase in the level of their physical activity. The conventional view of the etiology of the training up type of stress fracture is that the remodelling processes are incapable of completing the necessary structural alterations before continued loading causes failure due to fatigue in the bone material.

In order to promote public education and public safety, equal justice for all, a better informed citizenry, the rule of law, world trade and world peace, this legal document is hereby made available on a noncommercial basis, as it is the right of all humans to know and speak the laws that govern them. (For more information: 12 Tables of Code ) Name of Standards Organization: Bureau of Indian Standards (BIS) Committee Designation: CED 48 Designator of Legally Binding Document: IS 13946 : Part 1 : 2022 Title of Legally Binding Document: Determination of Rock Stress-Code of Practice - Part 1 Using the Hydraulic Fracturing Test and Hydraulic Tests on Pre-Existing Fractures Techniques Number of Amendments: 0 Status: Active Additional Info: LEGALLY BINDING DOCUMENT Step Out From the Old to the New --Jawaharlal Nehru

This article is from Indian Journal of Orthopaedics , volume 48 . Abstract None

Polly de Mille, exercise physiologist, discusses my VO2 max test results and how to incorporate them in to zone training. She discusses what about a fat adapted diet is ideal for distance runners, how to prevent injuries, and how exercise is the best medicine you can take. Serena Marie, RD, talks about the female triad and how \"calories in, calories out\" is just not a good idea. Stephen Brown talks about his new book, Relentless Mettle - My Cancer, My Rules.

The overall aim of this research is to gain insight into the etiology of tibial stress fractures. Three dimensional motion analysis data along with structural data will be collected from 400 subjects (200 at each site) over a 3-year period. 30 of the subjects will have sustained a tibial stress fracture prior to the study and the other 370 will have not. Subjects will be recruited primarily from track teams, running clubs, and physicians local to the University of Delaware and University of Massachusetts. Within this Annual Report, information concerning adherence to work objectives, preliminary results with respect to the proposed hypotheses, and reportable outcomes are presented for the second year of the investigation. Overall, we have adhered to most work objectives and have proposed plans for rectifying any discrepancies. The preliminary analysis of the data demonstrates encouraging results and support of most hypotheses.

The goal of this project is to determine if calcium and vitamin D intervention can reduce the incidence of stress fracture by at least 50% in female Naval recruits during basic training. We will recruit 5200 recruits who will be randomly assigned to an intervention group given calcium 2000 mg and vitamin D 800 I.U. per day or a control placebo group. The recruit intervention and stress fracture monitoring will continue through 8 weeks of basic training. Positive findings from this study would provide support for the Navy to adopt an easy, low cost method of further decreasing incidence of stress fractures. In May 2004, the DOD approved our protocol amendment to perform peripheral quantitative computed tomography (pQCT) measurements on a subset of recruits. The purpose of the substudy is to examine potential mechanisms for increasing bone adaptation to intense mechanical loading. We are performing the pQCT measurements. To date we have enrolled 4454 female recruits into the study, and 3518 have completed. We are retaining about 79% of enrolled participants. We have no findings to date.

Low serum 25-hydroxyvitamin D [25(OH)D] levels cause rickets and osteomalacia, but it is unknown whether the condition increases risk of stress fractures in young adult. This study was conducted to determine if young women with low serum 25(OH)D have an increased risk of stress fracture compared to those at higher levels. Methods. The Department of Defense has collected and frozen serum from over nine million service members. Pre-fracture serum specimens from 600 female cases of stress fracture of the tibia or fibula that occurred during the first 180 days of active-duty were analyzed for 25(OH)D content. Specimens from 600 controls, individually matched to the cases on age (+/-2 years);race (white, black or other); length of service +/- 30 days; who had blood drawn within 2 days of the case; and were on active duty within 30 days of the case?s diagnosis also were analyzed. Findings: Higher serum 25(OH)D levels were associated with lower risk of stress fracture (p =0..02). A linear dose-response relationship with increasing serum 25(OH)D revealed 50% lower risk of stress fracture in the top compared to the bottom quintile (p trend = 0.02). Women in the lowest quintile (≤ 19.7 ng/ml) had a mean 25(OH)D of 13.9 ng/ml (standard deviation [SD] +/-4.0), while those in the highest ≥ 39.9 had a mean of 49.7 ng/ml (SD +/- 10.4 ng/ml). Interpretation. Lower incidence of stress fracture in women with serum 25(OH)D greater than approximately 40 ng/ml indicates a minimum clinical target for prevention.

This article is from Journal of the International Society of Sports Nutrition , volume 9 . Abstract Background: Appropriate and sufficient dietary intake is one of the main requirements for maintaining fitness and health. Inadequate energy intake may have a negative impact on physical performance which may result in injuries among physically active populations. The purpose of this research was to evaluate a possible relationship between dietary intake and stress fracture occurrence among combat recruits during basic training (BT). Methods: Data was collected from 74 combat recruits (18.2 ± 0.6 yrs) in the Israeli Defense Forces. Data analyses included changes in anthropometric measures, dietary intake, blood iron and calcium levels. Measurements were taken on entry to 4-month BT and at the end of BT. The occurrence of stress reaction injury was followed prospectively during the entire 6-month training period. Results: Twelve recruits were diagnosed with stress fracture in the tibia or femur (SF group). Sixty two recruits completed BT without stress fractures (NSF). Calcium and vitamin D intakes reported on induction day were lower in the SF group compared to the NSF group-38.9% for calcium (589 ± 92 and 964 ± 373 mg·d-1, respectively, p < 0.001), and-25.1% for vitamin D (117.9 ± 34.3 and 157.4 ± 93.3 IU·d-1, respectively, p < 0.001). During BT calcium and vitamin D intake continued to be at the same low values for the SF group but decreased for the NSF group and no significant differences were found between these two groups. Conclusions: The development of stress fractures in young recruits during combat BT was associated with dietary deficiency before induction and during BT of mainly vitamin D and calcium. For the purpose of intervention, the fact that the main deficiency is before induction will need special consideration.

Appropriate and sufficient dietary intake is one of the main requirements for maintaining fitness and health. Inadequate energy intake may have a negative impact on physical performance which may result in injuries among physically active populations. The purpose of this research was to evaluate a possible relationship between dietary intake and stress fracture occurrence among combat recruits during basic training (BT).

Stress fractures of bone constitute the most serious musculoskeletal overuse injury during military training of male and female recruits. The hypothesis of our study is that the onset of stress fractures can be predicted by monitoring the evolution of microdamage activity using acoustic emissions. During the first year bone tissue was procured and amassed for specimen preparation. A sufficient number of donor tibias have been obtained and have been machined into test specimens. The test system was redesigned after the first year to improve the performance of both the mechanical testing as well as the acoustic emission detection of microdamage events. Different groups of beams will be tested to varying degrees of mechanical property degradation and relationship between the acoustic event parameters and fatigue failure will be studied. The third year activities focused on eliminating the artifactual emissions generated by sample motion over the loading supports which confound legitimate emissions from bone microcracking, and, characterization of the AE emission strength at the source and attenuation over time.

The overall aim of this research is to gain insight into the etiology of tibial stress fractures. Three dimensional motion analysis data along with structural data will be collected from 400 subjects (200 at each site) over a 3-year period. 30 of the subjects will have sustained a tibial stress fracture prior to the study and the other 370 will have not. Subjects will be recruited primarily from track teams, running clubs, and physicians local to the University of Delaware and University of Massachusetts. Within this Annual Report, information concerning adherence to work objectives, preliminary results with respect to the proposed hypotheses, and reportable outcomes are presented for the third year of the investigation. Overall, we have adhered to most work objectives and have proposed plans for rectifying any discrepancies. The preliminary analysis of the data demonstrates encouraging results and support of most hypotheses.

The stress fracture is one of the most frequent injuries in peacetime military populations, responsible for the military's greatest drain of both lost recruit time and medical resources. Unfortunately, not until we improve our understanding of the causative agents of this pathology can we expect to take effective measures in diminishing its appearance. Thus far, the studies we have undertaken have demonstrated that the origins of the lesion stem from tissue remodeling to material microdamage. As importantly, the site of the lesion, when correlated to the mechanical environment to which the bone is subjected, emphasizes that the pathology predominates in areas of least strain, not those areas subject to greatest deformation. Finally, the pathology observed in the two animal models is histologically identical to that which occurs in the human condition, demonstrating that appropriateness of the extrapolation towards the pathogenesis of the human condition. These observations have led to the development of a new hypothesis which holds major implications towards the design and modification of recruit training regimen. Keywords: Stress fractures; Bone remodeling; Training; Muscle fatigue; Strain.

Department of Defense PIN 69034 PREVENTION OF STRESS FRACTURES IN MILITARY TRAINING EXPLAINS HOW TO IDENTIFY, TREAT AND PREVENT STRESS FRACTURES WHICH OFTEN OCCUR AMONG MEN AND WOMEN UNDERGOING MILITARY TRAINING.

Stress fractures of bone constitute the most serious musculoskeletal overuse injury during military training of male and female recruits. We believe that the cascade of events in stress fractures is structured as the upregulation of bone turnover, amplification of porosity, induction of greater local strains and associated increase in damage activity a priori to fracture. The hypothesis of our study is that the onset of stress fractures can be predicted by monitoring the evolution of microdamage activity using acoustic emissions. During the first year bone tissue was procured and amassed for specimen preparation. A new mechanical loading set up was designed and fabricated to improve the cyclic loading tests. Ristological protocols were developed for sequential labeling of bone tissue prior to and after mechanical loading to separate in vivo and in vitro microdamage. Acoustic emission tests were run on a preliminary group of samples and the characteristic of extraneous waveforms emanating from other sources were obtained for filtering purposes. In the overall the protocols have been finalized and the proposed tests will be accomplished during the second year.

Stress fractures of bone constitute the most serious musculoskeletal overuse injury during military training of male and female recruits. We believe that the cascade of events in stress fractures is structured as the upregulation of bone turnover, amplification of porosity, induction of greater local strains and associated increase in damage activity a priori to fracture. The hypothesis of our study is that the onset of stress fractures can be predicted by monitoring the evolution of microdamage activity using acoustic emissions. During the first year bone tissue was procured and amassed for specimen preparation. A new mechanical loading set up was designed and fabricated to improve the cyclic loading tests. Ristological protocols were developed for sequential labeling of bone tissue prior to and after mechanical loading to separate in vivo and in vitro microdamage. Acoustic emission tests were run on a preliminary group of samples and the characteristic of extraneous waveforms emanating from other sources were obtained for filtering purposes. In the overall the protocols have been finalized and the proposed tests will be accomplished during the second year.

The study group successfully performed two evaluations during this period. The new dual energy x-ray bone densitometer machine was updated with new software.... RA II, Stress, Bone, Scintigraphy, Volunteers.

Stress fractures result from repetitive loading and have been regarded as a mechanical fatigue-driven process. However, a number of studies indicate that increased remodeling precedes the occurrence of bone microdamage and stress fractures, suggesting a central role for bone remodeling in the pathogenesis of stress fractures. Our ongoing experiments test the hypothesis by pharmacological inhibition of bone remodeling will slow the subsequent accumulation of microdamage, diminishing the severity of the stress fracture. We are using a bisphosphonate (BIS) in the rabbit tibial stress fracture model, to test the hypothesis that reactive remodeling within the cortex drives the development of stress fractures. Results to date indicate that BIS antiresorptive therapy reduces the intensity of the stress fracture response, as indicated by (99m)Techneitum bone scans, with the uptake of (99m)Techneitum reduced by approximately 50 percent in treated animals as compared to saline-treated controls. However, BIS treatment attenuated, but did not completely prevent the stress fracture response. These data are consistent with the hypothesis that bone remodeling contributes to the pathogenesis of stress fracture. The implication of this suppression on the later accumulation of bone microcracks and the evolution of final stress fracture are unknown are currently under investigation.

Stress fractures result from repetitive loading and have been regarded as a mechanical fatigue-driven process. However, a number of studies indicate implicate increased bone remodeling in the pathogenesis of stress fractures. These experiments tested the hypothesis by pharmacological inhibition of bone remodeling will diminish the severity of the stress fracture and slow the accumulation of microdamage with resulting from chronic loading. Bisphosphonate (BIS) antiresorptive therapy was used to suppress remodeling in the rabbit tibial stress fracture model. BIS antiresorptive therapy reduced the extent of periosteal reactive bone, with the resulting fracture callus volume reduced by about 40 percent. Similarly, microdamage content in bone was reduced as well. These data are consistent with the hypothesis that bone remodeling contributes to the pathogenesis of stress fracture. We also report on the results of novel model for stress fracture healing. using adult rats, developed under the aegis of this program.

The sharp rise in physical demands initiated during basic training all too frequently will precipitate stress fractures in the lower appendicular skeleton of new recruits. During peacetime, stress fractures are by far the most common physical injury in the military population, and are responsible for the military's greatest drain of both lost recruit time and medical expense. The objective of this three year research program is to study the etiology of the stress fracture lesion, and isolate any aspects of a physical regime which may exacerbate this condition. To perform this mission, we are persuing two parallel experimental protocols: a) the effect of muscle fatigue on bone strain distributions and, b) the effect of repetitive cyclic loading on bone remodeling. The summation of these two protocols has already provided unique insight towards the effect of new strain regimens on skeletal remodeling, and almost certainly will isolate and identify specific activities which may accelerate the pathogenesis of this condition. Keywords: Stress physiology, Bone fractures, Fatigue physiology.

Thesis (M.D.)--Yale University, 1956

Stress fractures of bone constitute the most serious musculoskeletal overuse injury during military training of male and female recruits. We believe that the cascade of events in stress fractures is structured as the upregulation of bone turnover, amplification of porosity, induction of greater local strains and associated increase in damage activity a priori to fracture. The hypothesis of our study is that the onset of stress fractures can be predicted by monitoring the evolution of microdamage activity using acoustic emissions. During the first year bone tissue was procured and amassed for specimen preparation. A sufficient number of donor tibias have been obtained and have been machined into test specimens. The test system was redesigned after the first year to improve the performance of both the mechanical testing as well as the acoustic emission detection of microdamage events. Different groups of beams will be tested to varying degrees of mechanical property degradation and histological examination will be used to determine the relationship between the acoustic event parameters and the microdamage morphology. The first group of beams are to be tested in fatigue until failure and these tests are currently underway.

This second annual report reviews progress towards completing each of our three study tasks. Major accomplishments include IRB renewal for all study protocols, hiring and training of new staff at MGH, as well as the completing subject enrollment for Task 1 and continuing enrollment for Task 3. In study Task 1 we aim to determine the sex- and race-ethnicity-specific bone traits that may contribute to stress fracture risk in military recruits. We are ahead of schedule by increasing our study size and completing study enrollment, with 185 subjects enrolled (n= 50 White women, 50 White men, 51 Black women, 34 Black men). Data analysis and manuscript preparation are underway. In study Task 2 we aim to quantify changes in bone structure and bone metabolism in recruits before and after Basic Combat Training (BCT). Enrollment and data collection are complete, and data analysis is ongoing. Finally, for study Task 3 we aim to characterize recovery and predict bone-healing trajectories and develop return-to-duty guidelines. We hypothesize that changes in bone health during recovery from stress-fracture injury can be quantified and used to develop evidence-based RTD. Enrollment is underway, with 13 women with recent stress fracture enrolled.

The study group performed two evaluations during this period. 175 Cadets remain in the study. Nonparticipant are primarily due to resignation from the Academy. Body fat % for the men and women has remained the same. The women have increased weight indicating a gain in muscle mass. Lower extremity injuries have equalized in the two groups. There were more injuries in men (32%) than in women (27%) from January 9l to August 1991. Bone density and laboratory values are being automated presently. RAII; Stress; Bone; Scintigraphy; Volunteers.

The goal of this project is to determine if calcium and vitamin D intervention can reduce the incidence of stress fracture by at least 50% in female Naval recruits during basic training. We will recruit 5200 recruits who will be randomly assigned to an intervention group given calcium 2000 mg and vitamin D 800 I.U. per day or a control placebo group. The recruit intervention and stress fracture monitoring will continue through 8 weeks of basic training. Positive findings form this study would provide support for the Navy to adopt an easy, low cost method of further decreasing incidence of stress fractures.

The overall aim of this research is to gain insight into the etiology of tibial stress fractures. Three dimensional motion analysis data along with structural data will be collected from 400 subjects (200 at each site) over a 3-year period. 30 of the subjects will have sustained a tibial stress fracture prior to the study and the other 370 will have not. Subjects will be recruited primarily from track teams, running clubs, and physicians local to the University of Delaware and University of Massachusetts. Within this Annual Report, information concerning adherence to work objectives, preliminary results with respect to the proposed hypotheses, and reportable outcomes are presented for the third year of the investigation. Overall, we have adhered to most work objectives and have proposed plans for rectifying any discrepancies. The preliminary analysis of the data demonstrates encouraging results and support of most hypotheses.

Abstract Stress fractures (SF's) affect a substantial portion of military recruits. We are investigating the hypothesis that a germline mutations in the procollagen genes or specific allelic patterns in other candidate genes confer genetic susceptibility to SF. Clinical, biochemical epidemiological and bone scan data on Israeli male soldiers diagnosed with high grade SF's were compared with two control groups.

The overall aim of this research is to gain insight into the etiology of tibial stress fractures. Three dimensional motion analysis data along with structural data will be collected from 40 subjects (200 at each site) over a 3-year period. 30 of the subjects will have sustained a tibial stress fracture prior to the study and the other 370 will have not. Subjects will be recruited primarily from track teams, running clubs, and physicians local to the University of Delaware and University of Massachusetts. Within this Annual Report, information concerning adherence to work objectives, preliminary results with respect to the proposed hypotheses, and reportable outcomes are presented for the third year of the investigation. Overall, we have adhered to most work objectives and have proposed plans for rectifying any discrepancies. The preliminary analysis of the data demonstrates encouraging results and support of most hypotheses.

This article is from Indian Journal of Orthopaedics , volume 47 . Abstract Background:: Stress fractures of the naviculum bone are uncommon injuries occurring predominantly in athletes. These fractures are usually treated nonoperatively with a nonweight bearing cast for a minimum of 6 weeks followed by rehabilitation. Further, there is a paucity of literature on the long term clinical followup of these patients. These fractures do not heal predictably with conservative management, which does not inspire great compliance and their clinical outcome is variable. We report on the outcome of these fractures following early operative intervention by minimally invasive fixation and early weight bearing and rehabilitation. We propose that this is reliable and a successful treatment regimen and its role as the definitive management of this clinical problem should be explored. Materials and Methods:: Nine athletes with ten stress fractures of the navicular treated at our institution between April 1991 and October 2000. The mean age of the patients was 22.8 years (range 18-50 years). All patients were treated by minimally invasive screw fixation and early weight bearing mobilization without a cast. The average followup was 7 years (range 2-11 years). Results:: Seven of the nine patients returned to their pre-fracture level of sporting activity at an average of 5 months (range 3-9 months). One patient returned to full sporting activity following a delay of 2 years due to an associated tibial stress fracture and one patient had an unsatisfactory result. Long term review at an average of 7 years showed that six of these eight patients who returned to sports remained symptom free with two patients experiencing minimal intermittent discomfort after prolonged activity. Conclusions:: We recommend percutaneous screw fixation as a reliable, low morbidity procedure allowing early return to full sporting activity without long term complications or recurrences.

The objective of this twenty month contract has been to identify the causative mechanical factors responsible for the stress fracture lesion. Over this period, the research has focussed exclusively on an animal model developed specifically for this work, the functionally isolated avian ulna. The stress fracture protocols have exploited this model's ability to withstand, in vivo, high cyclic loading, applied both axially and torsionally, with the aim of identifying that specific mechanical agent within the physical regimen which stimulates this debilitating condition. Previous work from our group suggests that the lesion is a product of tissue remodeling (intracortical porosis), not material microdamage. As importantly, the site of the lesion, when correlated to the mechanical environment to which the bone is subjected, emphasizes that the pathology predominates in areas of least normal strain, not those areas subject to greatest deformation. Finally, the pathology observed in this animal model is identical to that which occurs in humans, demonstrating the appropriateness of using these studies to better understand the etiology of the human condition. From these developments, we proposed that the stress fracture lesions, or rather elevated intracortical remodeling, was not intensity dependent, but instead was a product of redundant, cyclic activity.

Stress fractures result from repetitive loading and have been regarded as a mechanical fatigue-driven process. However, a number of studies indicate implicate increased bone remodeling in the pathogenesis of stress fractures. Our experiments tested the hypothesis that pharmacological inhibition of bone remodeling will slow the accumulation of microdamage and diminish the severity of the stress fracture. Using a bisphosphonate (BIS) to suppress remodeling in the rabbit tibial stress fracture model, we found that antiresorptive therapy reduced the intensity of the stress fracture response in this model.(99mTechneitum uptake reduced by approximately 50 percent, size of the resulting fracture callus reduced by about 30-50% in BIS-treated animals) and a trend toward reduced bone microdamage accumulation. These data are consistent with the hypothesis that bone remodeling contributes to the pathogenesis of stress fracture. However, variability in this model was greater than expected, limiting our ability to move forward with this animal model. We also report on the results of novel model for stress fracture healing, using adult rats, developed under the aegis of this program.

The goal is to determine if calcium and vitamin 0 supplementation can reduce the incidence of stress fracture by at least 50% in female Naval recruits during basic training. The secondary goal is to examine the potential mechanisms for increasing bone adaptation to intense mechanical loading. The Command Officers at the Great Lakes Naval Station stopped the study on xxx because we had recruited our originally targeted sample size. We recruited 5201 females who were randomly assigned to calcium 2000 mg and vitamin 0 800 l.U. per day or a control placebo group. The intervention and stress fracture monitoring continued through 8 weeks of basic training. We were not able to recruit the targeted number of subjects for the sub-study designed to determine changes in moment of inertia using peripheral quantitative computed tomography(pOCT). We enrolled 148 (out of a target 560) In the 3703 participants who completed the main study we found that calciumiD supplementation decreased the incidence of stress fracture by 27%(p=0.02). Furthermorn supplementation suggest that supplementation can compensate for a history of low physical activity.

The goal is to determine if calcium and vitamin 0 supplementation can reduce the incidence of stress fracture by at least 50% in female Naval recruits during basic training. The secondary goal is to examine the potential mechanisms for increasing bone adaptation to intense mechanical loading. The Command Officers at the Great Lakes Naval Station stopped the study on xxx because we had recruited our originally targeted sample size. We recruited 5201 females who were randomly assigned to calcium 2000 mg and vitamin 0 800 l.U. per day or a control placebo group. The intervention and stress fracture monitoring continued through 8 weeks of basic training. We were not able to recruit the targeted number of subjects for the sub-study designed to determine changes in moment of inertia using peripheral quantitative computed tomography(pOCT). We enrolled 148 (out of a target 560) In the 3703 participants who completed the main study we found that calciumiD supplementation decreased the incidence of stress fracture by 27%(p=0.02). Furthermorn supplementation suggest that supplementation can compensate for a history of low physical activity.

The objective of this study was to examine the effect of physical training in adolescent males and females on the interrelationship of the hypothaliunic-pituitary-gonadal axis, bone mineral density, and incidence of stress fractures. Participants consisted of male and female Cadets enrolled at the U.S. Military Academy, West Point, NY. Both male and female Cadets had reduced plasma gonadal steroid levels during an intense period of physical training over the first six months of enrollment at the Academy. Female Cadets had a reduction in BMD with six months. Gains in bone mineral density were not noted until the second year in both males and females. In female Cadets who had persistently low estradiol levels, BMD did not increase over the study. In males with persistently low testosterone concentrations, BMD did not increase and was decreased compared to other subjects. The incidence of stress fractures was 6 percent and did not appear related to hypogonadism or low BMD. Initiation of rigorous physical training results in a period of hypogonadism and absence of BMD gain in both male and female adolescents. Persistence of hypogonadism is associated with attenuated BMD gain in both females and males. The initial incidence of stress fractures is similar in males and females and does not appear related to gonadal hormone levels or BMD. The undertajing by adolescents of rigorous physical training, which reduces gonadal steroid levels and BMD gain, does not appear to result in a significant incidence of stress fractures irrespective of gender.

Similar diagnostic criteria are used for pelvic stress fractures and musculoskeletal pelvic pain. Differential diagnosis is made with a three phase bone scan. Of fifty-four sequential female soldiers having the symptoms of pelvic area stress fractures, seven had positive bone scans. Subjects were stratified by stress fracture or musculoskeletal pain then randomized into placebo or real treatment groups. Treatment was exposure to pulsing electromagnetic fields five days per week until resolution of the problem according to pain ratings, bone scans, and return to duty. Only twelve subjects accepted treatment because it was impossible for most to do their jobs and come to the hospital every weekday for months. Seven subjects dropped out for the same reason. Thus, although both patients with stress fractures receiving a significant number of treatments improved and the three who only received a few treatments did not, the randomized portion of the study never completed a meaningful number of subjects. None of the subjects with musculoskeletal pain nor those receiving placebo treatment improved. The results indicate that pelvic stress fractures are being over-diagnosed. It is recommended that bone scans be given to soldiers meeting the diagnostic criteria early in the diagnostic/treatment process to avoid lengthy treatments for the wrong problem.

Stress fractures result from repetitive loading and have been regarded as a mechanical fatigue-driven process. However, histopathological data and experimental data from our laboratory suggests that increased remodeling precedes the occurrence of bone microdamage and stress fractures, suggesting a central role for increased intracortical remodeling in the pathogenesis of stress fractures. Thus, we propose that stress fracture occurs through a positive feedback mechanism, in which increased mechanical usage stimulates focal bone turnover, resulting in a locally increased in porosity. Microdamage accumulation and stress fractures result from continued cyclic loading of this transiently osteopenic bone. The proposed experiments test the hypothesis by pharmacologically inhibiting the bone remodeling response, the subsequent accumulation of microdamage and the severity of the stress fracture can be diminished. In the proposed experiments, this hypothesis is being tested experimentally in the rabbit tibial stress fracture model, which was developed in our laboratory. To test the hypothesis that reactive remodeling within the cortex drives the development of stress fractures, the effect of remodeling suppression using a bisphosphonate on the accumulation of bone microdamage and diminishing the severity of stress fracture will be examined. Outcomes of these experiments will be assessed using bone scintigraphy, histomorphometry and biomechanical approaches.

Stress fractures usually take a long time to heal and prevent soldiers, from participating in most physical activities. About half of the trainees at Ft. Sill diagnosed with stress fractures never return to active duty. The pilot tests the feasibility of using pulsing electromagnetic fields, such as those used to potentiate the healing of non-unions, to speed healing of stress fractures. In the first trial, the field coil was embedded in the cast to produce a magnetic field around the fracture. The unit was supposed to be used for a minimum of six weeks but, due to change in treatment policies resulting from a turnover in staff with DESERTS SHIELD, the units were only used for a few weeks. Eighteen trainees used the units in their casts, ten just had casts(the standard treatment) during the treatment period and thirty-one just had the standard treatment before the treatment period. There was no difference between number of days it took those numbers of the groups able to return to duty to do so. However, Only two of the treated soldiers had MEBs while twenty of the controls did. The pilot will continue as an unfunded study at FT. Sill. The proposed work and new investigators were identified in the annual report to MDRC for this project dated 6 November, 1992

This study examined the potential cost savings of implementing programs to reduce the incidence of lower extremity stress fractures in basic training. The author predicted a potential cost savings of over one million dollar annually based on a 60% reduction in incidence of stress fractures. The author proposes a program to implement that should achieve a 60% reduction in the incidence of stress fractures.

The goal of this project is to determine if calcium and vitamin D intervention can reduce the incidence of stress fracture by at least 50% in female Naval recruits during basic training. The secondary goal is to examine the potential mechanisms for increasing bone adaptation to intense mechanical loading. We will recruit 5200 recruits who will be randomly assigned to an intervention group given calcium 2000 mg and vitamin D 800 I.U. per day or a control placebo group. The intervention and stress fracture monitoring will continue through 8 weeks of basic training. In a subset of 560 subjects, we will obtain peripheral quantitative computed tomography(pQCT)measurements of the tibia at baseline and end of training to determine changes in moment of inertia. To date we have enrolled 4606 subjects and completed 3518. We have enrolled 113 into the pQCT substudy. We continue to enroll and collect data. To date, 249 subjects have sustained stress fractures. There have been no adverse events since the last annual report. We have requested a no-cost extension to complete the study. We have no findings to report.

Stress fractures result from repetitive loading and have been regarded as a mechanical fatigue-driven process. However, data suggests that increased remodeling precedes the occurrence of bone microdamage and stress fractures, suggesting a central role for increased intracortical remodeling in the pathogenesis of stress fractures. Our ongoing experiments test the hypothesis by pharmacological inhibition of bone remodeling will slow the subsequent accumulation of microdamage, diminishing the severity of the stress fracture. We are using a bisphosphonate (BP) in the rabbit tibial stress fracture model, to test the hypothesis that reactive remodeling within the cortex drives the development of stress fractures. Ongoing studies suggest that BP antiresorptive therapy reduces the intensity of the stress fracture response, as indicated by technetium bone scans. This effect was most pronounced with short-term loading (3 weeks), with (99) technetium uptake in BP treated animals reduced approximately 25 percent from control levels; this effect was diminished by 6 weeks of loading. Reduction of bone 99technetium uptake at 3 weeks in drug-treated animals is consistent with suppression of the acute activation of new intracortical resorption foci by bisphosphonates. The implication of this suppression of the later accumulation of bone microcracks, and the evolution of final stress fracture, are unknown.

This article is from Indian Journal of Orthopaedics , volume 47 . Abstract Neglected or late presenting femoral neck stress fractures are often associated with varus deformity, with potential risks of nonunion and osteonecrosis. We proposed a surgical technique whereby a wedge osteotomy was performed at the basal part of the neck, on the tensile surface, keeping the inferomedial femoral neck as a hinge. The femoral shaft was abducted to close the osteotomy site and it was fixed with three cannulated cancellous screws. Three military recruits who presented with neglected femoral neck stress fracture with varus deformity were operated on with the proposed modified femoral neck valgus osteotomy. All the fractures united without any complications and the patients resumed their professional activity.

Stress fractures result from repetitive loading and have been regarded as a mechanical fatigue-driven process. However histopathological data and experimental data from our laboratory suggests that increased remodeling precedes the occurrence of bone microdamage and stress fractures suggesting a central role for increased intracortical remodeling in the pathogenesis of stress fractures. Thus we propose that stress fracture occurs through a positive feedback mechanism in which increased mechanical usage stimulates focal bone turnover resulting in a locally increased in porosity. Microdamage accumulation and stress fractures result from continued cyclic loading of this transiently osteopenic bone. The proposed experiments test the hypothesis by pharmacologically inhibiting the bone remodeling response the subsequent accumulation of microdamage and the severity of the stress fracture can be diminished. In the proposed experiments this hypothesis is being tested experimentally in the rabbit tibial stress fracture model which was developed in our laboratory. To test the hypothesis that reactive remodeling within the cortex drives the development of stress fractures the effect of remodeling suppression using a bisphosphonate on the accumulation of bone microdamage and diminishing the severity of stress fracture will be examined. Outcomes of these experiments will be assessed using bone scintigraphy histomorphometry and biomechanical approaches.

Stress fractures result from repetitive loading and have been regarded as a mechanical fatigue-driven process. However histopathological data and experimental data from our laboratory suggests that increased remodeling precedes the occurrence of bone microdamage and stress fractures suggesting a central role for increased intracortical remodeling in the pathogenesis of stress fractures. Thus we propose that stress fracture occurs through a positive feedback mechanism in which increased mechanical usage stimulates focal bone turnover resulting in a locally increased in porosity. Microdamage accumulation and stress fractures result from continued cyclic loading of this transiently osteopenic bone. The proposed experiments test the hypothesis by pharmacologically inhibiting the bone remodeling response the subsequent accumulation of microdamage and the severity of the stress fracture can be diminished. In the proposed experiments this hypothesis is being tested experimentally in the rabbit tibial stress fracture model which was developed in our laboratory. To test the hypothesis that reactive remodeling within the cortex drives the development of stress fractures the effect of remodeling suppression using a bisphosphonate on the accumulation of bone microdamage and diminishing the severity of stress fracture will be examined. Outcomes of these experiments will be assessed using bone scintigraphy histomorphometry and biomechanical approaches.

PREVENTION OF STRESS FRACTURES IN MILITARY TRAINING - Department of Defense 1978 - PIN 69034 - EXPLAINS HOW TO IDENTIFY, TREAT AND PREVENT STRESS FRACTURES WHICH OFTEN OCCUR AMONG MEN AND WOMEN UNDERGOING MILITARY TRAINING.

The literature and clinical experience indicate that the overwhelming incidence of pelvic area stress fractures is among women engaged in strenuous activities. Pulsing electromagnetic fields (PEMFs)have been shown to speed the healing of non-union fractures and we have used them successfully to treat stress fractures in the lower limbs. All women at Ft. Lewis who have the clinical symptom complex indicative of pelvic area stress fractures are being referred for bone scans. Thirty soldiers meeting the criteria have had bone scans but only four have been positive. Subjects with negative bone scans but meeting all other criteria are placed into the musculoskeletal pelvic pain group. Patients are stratified by presence or absence of a fracture and then randomized into actual PEMF and placebo PEMF groups and treated for one hour per day until they return to duty. Changes in the bone scan are used to determine differences between the fracture groups while differences in pain and return to duty are used to determine differences between the musculoskeletal groups. Results to date indicate that pelvic stress fractures are being misdiagnosed. If these results are confirmed, treatments for women showing this symptom complex may be changed as they receive treatments designed to ameliorate stress fractures.