Development Of Stress Fractures Research Articles

Tibial strains are sensitive to speed perturbations, but not grade perturbations, during running.

A fatigue-failure process is hypothesized to govern the development of tibial stress fractures, where bone damage is highly dependent on the peak strain magnitude. To date, much of the work examining tibial strain during running has ignored uphill and downhill running despite the prevalence of this terrain. This study examined the sensitivity of tibial strain to changes in running grade and speed using a combined musculoskeletal-finite element modelling routine. Seventeen participants ran on a treadmill at ±10, ±5 and 0deg; at each grade, participants ran at 3.33 m s-1 and at a grade-adjusted speed of 2.50 and 4.17 m s-1 for uphill and downhill grades, respectively. Force and motion data were recorded in each grade and speed combination. Muscle and joint contact forces were estimated using inverse-dynamics-based static optimization. These forces were applied to a participant-adjusted finite element model of the tibia. None of the strain variables (50th and 95th percentile strain and strained volume ≥4000 με) differed as a function of running grade; however, all strain variables were sensitive to running speed (F1≥9.59, P≤0.03). In particular, a 1 m s-1 increase in speed resulted in a 9% (∼260 με) and 155% (∼600 mm3) increase in peak strain and strained volume, respectively. Overall, these findings suggest that faster running speeds, but not changes in running grade, may be more deleterious to the tibia.

Differential roof cutting for roadway support in dual gob-side entry retention on a single working face − Multilevel continuous anchor-grouting control technology: A case study

The coal pillar-free gob-side entry retention technology (GER), which enhances resource recovery rates and reduces the amount of tunnel excavation, has been applied in multiple mining areas in China. However, cases of implementing gob-side entry retention on both sides of a single working face are rare. The asynchronous extraction of long-distance working faces leads to significant differences in the stress environment of roadways on both sides, and uniform technical means are poorly adapted to the control of surrounding rock on both sides, affecting the safe and efficient production. This paper, taking the dual gob-side entry retention on both sides of the 61001 W working face with thick mudstone roofs in Zhao Guan Coal Mine, Shandong Province, as the engineering background, utilizes a combination of theoretical calculations, numerical simulations, and on-site detailed monitoring to analyze the uncoordinated deformation characteristics of the upper part bulging and the lower part concaving of the two roadways. It clarifies the differentiated spatiotemporal evolution law of the number of fractures and the development turning points at different depths of the surrounding rock of the two entries, revealing the differential deformation mechanism of the surrounding rock of the two entries caused by stress state and fracture development differences. A “cutting roof to relieve pressure-multilevel continuous anchor-grouting” combined control technology system is proposed. By cutting off the stress transmission of the roof through drilling and blasting, and then reconstructing the integrity of the surrounding rock and improving the rock strength with the help of anchor-grouting. With the application of this new technology, the deformation of the surrounding rocks of the two entries was reduced by more than 60 % and 29 %, respectively, and the maximum crack depth of the roof was controlled within 3 m, significantly enhancing the stability of the roadways. The research results of this paper provide a reference for the control of surrounding rock in gob-side entry retention under similar conditions.

Stress fractures of the foot - current evidence on management

Stress fractures are a consequence of repeated submaximal loads with inadequate time for recovery and biologic repair or remodelling. The foot and ankle complex (FAC) represents a common site for development of stress fractures. Whilst the overall incidence of stress fractures is low, they are prevalent in athletes and military personnel causing significant time away from sports or work. Within these populations, certain stress fractures directly correlate to specific activities.Factors that commonly influence these fractures include an acute increase in new repetitive physical activity combined with muscle fatigue, training errors or improper athletic techniques, which challenge the regenerative and remodelling capacity of bone. Depending on the site that is subject to repetitive loading, various biomechanical factors can result in abnormal concentration of forces to specific areas of the FAC resulting in stress fracture. Decreased bone marrow density (BMD) is a major biologic cause for developing stress fractures. The female athlete triad comprising eating disorder, amenorrhea and osteoporosis in competitive athletes also predisposes to stress fractures. Vitamin D deficiency is also postulated to be the cause of these fractures and may contribute to poor healing.Clinical presentation is usually with vague pain of insidious onset which worsens with activity and improves with rest. Diffuse tenderness over the affected bone is common with only a minority having any visible swelling. Plain radiographs are the first line of investigation but rarely reveal an obvious fracture. MRI scans aid in diagnosis and CT scans help in treatment and characterisation of the fracture and monitor healing.Management relates to the site of injury, which stratifies them into high or low-risk. Stress fractures of the calcaneus, cuboid and cuneiforms are classed as low-risk fractures as they usually heal with simple activity modification or short duration of non-weight bearing. Stress fractures of the navicular, talus and hallucal sesamoids are classed as high-risk fractures due to higher rates of non-union and prolonged recovery time. Metatarsal fractures can be considered high or low-risk depending on location. These warrant aggressive management, often requiring surgical intervention. Adjuncts such as vitamin D supplements, external shockwave therapy, low-intensity pulsed ultrasound therapy have been used with varying success but there remains little supportive evidence of superiority in the available literature.

Study on Sealing Depth Optimization of Gas Drainage Borehole in Coal Seam

To determine the reasonable sealing depth of the drainage borehole in the coal seam along lane W33011 of the Sihe coal mine and improve sealing quality based on the mine geological conditions, FLAC3D numerical simulation software was used to simulate the stress distribution and fracture development of coal body around the roadway after the roadway excavation. YFZ3 hole sealing quality detector was adopted to detect the hole sealing quality and leakage position. The reasonable drilling depth in the test area was determined to be 15m, effectively improving the gas drainage effect. This technology has important reference significance for improving the quality of hole sealing in other mines.

The law of blast stress wave propagation and fracture development in soft and hard composite rock

The process of blasting stress wave propagation and crack propagation is directly affected by the physical properties of the rock mass and internal joints in the rock. In soft and hard rock layers, the blasting process is more complicated since the blasting stress wave needs to penetrate two kinds of rocks with different physical properties and the interface between soft rock and hard rock. In this study, the modal transformation of stress waves at the interface of layered composite rock was analyzed, and the process was reproduced by finite element analysis. Furthermore, the development law of cracks was explored. The research results demonstrated that in the single blasting-hole model, a triangular crack area caused by reflected stress waves appeared at the rock interface of rock medium I near the blast hole. In rock medium II, the tensile crack generated by the interface wave appeared on the side away from the blast hole. Besides, the development of the tensile crack was associated with the incident mode of the blast stress wave and the incident angle. In the deep hole blasting model, the incidence of the detonation wave front from hard rock to soft rock promoted the fragmentation of the hard rock.

Tibial-fibular geometry and density variations associated with elevated bone strain and sex disparities in young active adults.

Tibial stress fracture is a common injury in runners and military personnel. Elevated bone strain is believed to be associated with the development of stress fractures and is influenced by bone geometry and density. The purpose of this study was to characterize tibial-fibular geometry and density variations in young active adults, and to quantify the influence of these variations on finite element-predicted bone strain. A statistical appearance model characterising tibial-fibular geometry and density was developed from computed tomography scans of 48 young physically active adults. The model was perturbed ±1 and 2 standard deviations along each of the first five principal components to create finite element models. Average male and female finite element models, controlled for scale, were also generated. Muscle and joint forces in running, calculated using inverse dynamics-based static optimization, were applied to the finite element models. The resulting 95th percentile pressure-modified von Mises strain (peak strain) and strained volume (volume of elements above 4000 με) were quantified. Geometry and density variations described by principal components resulted in up to 12.0% differences in peak strain and 95.4% differences in strained volume when compared to the average tibia-fibula model. The average female illustrated 5.5% and 41.3% larger peak strain and strained volume, respectively, when compared to the average male, suggesting that sexual dimorphism in bone geometry may indeed contribute to greater stress fracture risk in females. Our findings identified important features in subject-specific geometry and density associated with elevated bone strain that may have implications for stress fracture risk.

Digital phenotyping in transmission constrained, military operational environments

Introduction: Stress fracture injuries affect defence forces worldwide. The sudden onset of high-impact exercise, insufficient recovery, and suboptimal conditions (e.g., energy and sleep restriction) elicit injuries in 5 to 10% of military recruits. Women are three times more likely to develop stress fractures than men1, and this risk of injury is projected to increase further in women employed in ground close combat roles2. Oestrogens have two distinct roles in women’s bone biology. 1. Oestrogens influence the size and shape of bone during puberty, promoting endosteal contraction, and resulting in a smaller cross-sectional area than men. A smaller bone size contributes to the increased risk of stress injuries under loading in women. 2. Oestrogens prevent excessive bone resorption by suppressing RANKL expression. Low oestrogen caused by suppression of the hypothalamic-pituitary-ovarian axis—indicated by a loss of menstrual periods—is highly prevalent during arduous exercise3 and demineralises bone. Cessation of menstrual periods, amenorrhoea, is a risk factor for stress fracture injury4. Ovulation is a key event in the menstrual cycle, preceded by a peak in oestrogen concentration, and followed by increased progesterone concentration. Anovulatory cycles are characterised by low, non-cyclical oestrogen and progesterone. Ovulation is a sign of menstrual health and informs women of their reproductive hormonal status. Non-invasive, innovative methods of detecting ovulation are disrupted approaches to mitigating injury risk in women. Methods: This presentation will provide an overview of the epidemiology of stress fracture injuries in military personnel, reporting the prevalence and patterns of injuries observed during basic military training. The role of the sex steroid hormones on bone health will be described, and the utility of wearables to detect ovulation appraised. Primary evidence will be obtained from open-source, peer-reviewed literature, and wearable data will be drawn from both published studies and preliminary data from the British Army’s EMPOWER study. Conclusions: A high proportion of women experience menstrual disturbances during arduous training and suffer a high incidence of stress fractures. The validity of wearable technology for women to detect ovulation during arduous military training, characterised by high physical demands, stress, and restricted energy and sleep, is under investigation. Acknowledgements: This work was funded by the British Army. References 1O’Leary TJ, Wardle SL, Rawcliff AJ, et al. Understanding the musculoskeletal injury risk of women in combat: the effect of infantry training and sex on musculoskeletal injury incidence during British Army basic training. BMJ Mil Health. 2020; 0:1-5. https://doi.org/10.1136/jramc-2019-001347 2Ministry of Defence. Women in Ground Close Combat Roles - Interim Health Report 2016. Available at: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/536381/20160706_ADR006101_Report_Women_in_Combat_WEB-FINAL.PDF Accessed 31 Aug 2021. 3Gifford RM, O’Leary TJ, Wardle SL, et al. Reproductive and metabolic adaptation to multistressor training in women. Am J Physiol Endoc-M 2021; 321(2):E281-E291. https://doi.org/10.1152/ajpendo.00019.2021 4Ackerman KE, Sokoloff NC, Maffazioli GDN, et al. Fractures in relation to menstrual status and bone parameters in young athletes. Med Sci Sports Exerc 2015; 47(8):1577-1586. https://doi.org/10.1249/MSS.0000000000000574

Surgically Treated Femoral Neck Stress Fractures Are Likely to Result in Military Separation During Basic Combat Training.

Femoral neck stress fractures are a common condition affecting military service members, most noticeably during basic combat training. Previous studies have investigated the risk factors for femoral neck stress fracture development in basic trainees and outcomes associated with treatment; however, few studies have focused on operatively treated femoral neck stress fracture in the military trainee. Doing so would be important not only for the military, but also providers caring for athletes, such as distance runners, who have a heightened risk for femoral neck stress fracture development. (1) What proportion of US Army trainees completing basic combat training at Fort Jackson, SC, USA, who undergo surgery for femoral neck stress fracture during basic training subsequently leave military service because of the injury? (2) What factors are related to the patient or the fracture are associated with a higher likelihood of military separation? (3) What factors on the initial MRI are associated with progression of the stress fracture extent? A retrospective study of a longitudinally maintained database of stress injuries involving basic combat trainees from a single military post was reviewed over a 3-year period. Inclusion criteria included basic trainees undergoing surgery for a femoral neck stress fracture between January 2018 and June 2020 with a minimum of 1-year follow-up. Surgery was indicated for service members with complete and tension-sided femoral neck stress fractures and those with high risk compression-sided stress fractures, generally representing fractures involving more than 50% of the femoral neck width. Over the study period, 57 service members (51% [29 of 57] women with a mean age of 24 years) underwent surgery for a femoral neck stress fracture, and all 57 had a minimum of 1-year follow-up. Identified service members underwent independent data collection including injury and radiographic parameters based on chart and imaging review. Documented fracture line progression on repeat imaging was present in 39% of service members, with a mean fracture line progression of 55% of the femoral neck width. Service members were subdivided based upon the ability to return to military service at 1 year. Univariate analysis was performed using patient and injury variables to identify factors associated with the ability to return to military service. Overall, 58% (33 of 57) of service members who had a femoral neck stress fracture treated surgically underwent military separation. A higher proportion of service members who demonstrated fracture line progression leading to surgical treatment remained in the military (58% [14 of 24] versus 30% [10 of 33]; odds ratio 0.3 [95% confidence interval (CI) 0.1 to 0.9]; p = 0.03). With the numbers available, we found no other patient- or fracture-related variables associated with military separation, although we suspect we may have been underpowered on some of these comparisons, in particular gender (61% [20 of 33] of individuals separated after surgery for this injury were women compared with 38% [9 of 24] who were retained; OR 2.6 [95% CI 0.9 to 7.56]; p = 0.09). The extent of osseous edema on T1-weighted imaging in association with a hip effusion demonstrated a significant positive correlation with final fracture percentage (r = 0.62; p = 0.003). Military service members with a femoral neck stress fracture initially managed nonoperatively but with progression of the fracture line requiring surgical intervention were more likely to return to military duties and complete basic combat training, suggesting that early diagnosis of femoral neck stress fractures may be associated with better functional recovery after surgical treatment. Additionally, the extent of the osseous edema on initial MRI T1-weighted imaging sequences may help predict the final extent of femoral neck stress fractures on repeat imaging. Further investigations should incorporate patient-reported outcomes and further explore factors associated with fracture progression and the inability to return to active duty or sport. Level III, therapeutic study.

Structural Characteristics and Evolution Process of the Metamorphic Buried Hill: A Case of BZ Oilfield in Bohai Bay, China

Bozhong oilfield which is abbreviated as BZ oilfield is the first oilfield with deep metamorphic buried hill that is discovered reserves of billion-ton in Bohai Bay. Affected by multi-stage tectonic movements, the distribution of fractures is very complex in this area, therefore it is significant to study the evolution of structures for understanding the distribution of fractures. In view of the complexity on the tectonic evolution of the buried hill region in the study area, the influence of tectonic movements on the formation of fractured reservoir is analyzed, and the research results lay the foundation for the efficient development in this type of the oilfield. The results show that main faults, which is formed during early Indosinian and Yanshanian period, are mainly developed in the BZ oilfield area, and the fracture strike has mainly east-west and north-east-east trend. Based on the analysis of the relationship among tectonic evolution, regional stress field and fracture development, it is considered that Indosinian extrusion is the main reason for the formation of main direction faults in the study area. Yanshanian strike-slip transformation and Himalayan reactivation further controlled the development of the fractured reservoirs in the later stage, and formed the present fracture network system. Well block 5 is located in passive plate system during Indosinian period, it is affected by Himalayan stretching and long-term activation of large faults in the later stage, so that the effective fractures are relatively developed. The result plays an important role in guiding the overall plan deployment of the BZ oilfield.

Coaches' Attitudes Toward Campus Board Training in Adolescent Climbers in the United States.

Campus board training in adolescent climbers is controversial. Evidence, albeit limited, suggests this type of training may lead to the development of finger epiphyseal stress fractures. The purpose of the present study was to investigate coaches' attitudes toward campus board training in the United States. Surveys were sent to 116 coaches at gyms across the United States with affiliated adolescent climbing teams. Outcomes collected included demographic information, training time, campus board use prevalence, coaches' attitudes toward campus board use, and willingness to participate in future research. Seventy-three coaches representing 3090 adolescent climbers completed the survey. Forty-six coaches (63%) reported using full weight (no foot contact) campus board training in some or all of their climbers. A variety of factors were cited by coaches when deciding which climbers should or should not use the campus board, including physical maturity, climbing ability, and age, among others. Climbing coaches in the United States disagree on the use of campus board training in adolescent climbers. Some coaches avoid using this training modality entirely, whereas others believe certain climbers can use it safely. There is lack of consensus in determining who those certain climbers are.

The Relationship of 24-Hour Recalls and Diet Questionnaires for Estimating Calcium and Vitamin D Intakes in Young Women

ObjectivesFemale military recruits are at risk for developing stress fractures during initial military training (IMT). Accurate assessment of both calcium (Ca) and vitamin D (vit D) intake may support the development of targeted dietary interventions for those at risk of deficiency. The objective of this study was to investigate the relationships between different dietary assessment methods for estimated dietary Ca and vit D intakes in a healthy population. MethodsActive, healthy females (18–42 yr, 19–26 kg/m2 body mass index) recruited for an exercise study were included. Study dietitians administered: three 24-hour recalls (24HR) (baseline and before two exercise interventions), full-length Block 2014 Food Frequency Questionnaire (FFQ) (baseline), and Block Calcium and Vitamin D Screener (baseline). Twenty-four HR data were averaged and then quantified by Food Processor SQL. Block questionnaires were analyzed by NutritionQuest. Ca and vit D intakes were energy adjusted using the density method for all assessment methods except the screener. Means, standard deviations (SD), and correlations between 24HR variables were analyzed using SPSS. ResultsTwenty-one participants completed the study: (mean ± SD) 26.2 ± 6.7 yr, 22.76 ± 2.12 kg/m2. Estimated intakes from the 24HR, FFQ, and screener for Ca (mg/d) were 741 ± 403,1001 ± 420, and 446 ± 270, respectively and for vit D (μg/d) were 2.8 ± 3, 4.6 ± 2.6, and 1.8 ± 1.6, respectively. Moderate, positive correlations were found between the 24HR and unadjusted FFQ Ca intake (r = 0.636, P = 0.002), and the 24HR and adjusted FFQ vit D intake (r = 0.561, P = 0.008). No significant correlations were observed between the nutrients of interest as measured by the 24HR and screener. ConclusionsIntake estimates of Ca and vit D from the full-length FFQ displayed moderate agreement with those estimated by the 24HR, and the FFQ produced relatively higher estimates. Given this, the FFQ may be more practical for use in an IMT setting, for estimating relative Ca and vit D intakes, than the 24HR to identify individuals who may benefit from interventions promoting bone health. Funding SourcesDefense Health Program. The views expressed in this abstract are those of the authors and do not reflect the official policy of the Department of Army, Department of Defense, or the U.S. Government.

Bony Stress and Its Association With Intervertebral Disc Degeneration in the Lumbar Spine: A Systematic Review of Clinical and Basic Science Studies.

Study Design:Translational review encompassing basic science and clinical evidence.Objectives:Multiple components of the lumbar spine interact during its normal and pathological function. Bony stress in the lumbar spine is recognized as a factor in the development of pars interarticularis defect and stress fractures, but its relationship with intervertebral disc (IVD) degeneration is not well understood. Therefore, we conducted a systematic review to examine the relationship between bony stress and IVD degeneration.Methods:Online databases Scopus, PubMed and MEDLINE via OVID were searched for relevant studies published between January 1980-February 2020, using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines. Two authors independently analyzed the data, noting characteristics and biases in various studies.Results:Thirty-two articles were included in the review: 8 clinical studies, 9 finite element modeling studies, 3 in-vivo biomechanical testing studies, and 12 in-vitro biomechanical testing studies. Of the 32 articles, 19 supported, 4 rejected and 9 made no conclusion on the hypothesis that there is a positive associative relationship between IVD degeneration and bony stress. However, sufficient evidence was not available to confirm or reject a causal relationship.Conclusions:Most studies suggest that the prevalence of IVD degeneration increases in the presence of bony stress; whether a causal relationship exists is unclear. The literature recommends early diagnosis and clinical suspicion of IVD degeneration and bony stress. Longitudinal studies are required to explore causal relationships between IVD degeneration and bony stress.

Stress Fracture Tibia among Military Recruits Management by Patellar Tendon Bearing Cast

Introduction: Lower limb overuse injuries are common features of military training. Female recruits have significantly higher incidence of fracture than male recruits. In addition to the cost and time of rehabilitation, injury leads to disillusionment among recruits. Conventionally stress fracture tibia is treated with long leg posterior cast for 6-8 weeks but little is known about the length of time required for rehabilitation and to return to pre-injury level.
 Objectives: To see the outcome of management of stress fracture tibia among military recruits treated with Patellar Tendon Bearing (PTB) cast for 8 weeks and to find out the rehabilitation time to return to pre-injury level.
 Materials and Methods: This prospective study was conducted in Combined Military Hospital, Bogura, Bangladesh, from January 2015 to December 2016. Out of 2600 recruits 74 (male 60 females 14) were diagnosed as case of stress fracture tibia during the period. They were treated by PTB cast for 08 weeks and their treatment and rehabilitation to pre-injury level (follow-up) were recorded prospectively.
 Results: Total 85 patients were clinically suspected to have stress fracture tibia, out of them 74(87.06%) patients were finally diagnosed as case of stress fracture. Of these 74 patients 44(59.46%) were diagnosed by initial x-ray and 30(40.54%) were diagnosed by MRI scan. Prevalence of stress fracture in male was 2.45% and in female recruits 9.33%, overall prevalence was 2.85%.About 56(75.67%) patients developed stress fracture in 0-8 weeks of training, mean rehabilitation time to return to pre-injury level was 15.51 weeks, there was no recurrence of stress fracture and all the patients completed 12 months training, none of them was relegated or withdrawn from training on medical ground.
 Conclusion:Patellar tendon bearing cast is an effective, technically simple method for treating stress fracture of tibia in military recruits with excellent outcome. This method not only treats the fracture but also prevents depressive disorders.
 JAFMC Bangladesh. Vol 15, No 2 (December) 2019: 196-199

Bone density and its relation to the development of acromial stress fracture following reverse total shoulder arthroplasty.

Postoperative acromial stress fracture is a troublesome postoperative complication after reverse shoulder arthroplasty. Our study aims to utilize routinely performed preoperative computed tomography scans to identify differences in the material properties of the acromion in patients who did and did not develop a postoperative acromial stress fracture. Treatment records and computed tomography scans for 99 reverse shoulder arthroplasties were collected. Scans were calibrated using a phantom and transferred for post-processing where the acromion, full scapula, and humeral head were isolated. The final segmented model was used to assess acromial volume and volumetric bone mineral density for each region of interest. There was no association between age and volumetric bone mineral density in any region of interest (all R 2 ≤ 0.048, all p > 0.082). Patients who developed an acromial stress fracture were not significantly different from those who did not in terms of age, acromial volume, or acromial volumetric bone mineral density (all p > 0.559). Patients with known osteoporosis or osteopenia had slightly lower volumetric bone mineral density, but the differences were not significant (all p ≥ 0.072). Postoperative acromial fractures following reverse shoulder arthroplasty cannot be predicted by computed tomography-derived volumetric bone mineral density or volume. These mechanical characteristics also do not predictably decrease with age or osteoporosis diagnosis.

Numerical Study on Stress Relief and Fracture Distribution Law of Floor in Short-Distance Coal Seams Mining: A Case Study

During the mining process of short distance coal seams group with high gas content, excavation of the protective coal seam will result in stress relief and fracture development which provides pathways for gas migration. Gas stored in the lower coal seam moves along the mining-induced fracture to the floor of the upper working face, which may cause the gas over-limit at the upper coal seam. This paper takes the short distance coal seams group in Xinghua coal mine as an example, theoretical analysis, numerical simulation and field monitoring are comprehensively applied to study the floor failure mechanism, pressure relief law and dynamic evolution of cracks induced by the mining of the second-right working face. The results showed that as the upper coal seam gradually advances, the pressure relief angle of roof and floor gradually decreases, and the pressure relief range and floor failure depth gradually increase. After the working face of the upper coal seam is advanced 100 m, the range of the pressure relief in the surrounding coal and rock masses approaches stable; the cracks in the shallow depth are mainly with small angles or type II shear cracks, and the cracks in the large depth are mainly shear-expansion with lager angles, and the amount of fractures in the floor reduces with the increase of the depth of the floor. It was found that the mining-induced fractures in the floor is distributed in the shape of an “O” ring, and as the working face advances, the range of this “O”-shaped crack circle keeps moving forward but the width of the crack circle is basically unchanged. Finally, the low-level drilling field was used to control the gas from lower coal seams according to the stress relief and fracture distribution law, which achieved satisfied application effect and provided guidance for mine gas extraction in similar mining conditions.

Differences in the principal strain angles during activities performed on natural hilly terrain versus engineered surfaces

BackgroundTibial stress fractures in military recruits occur beginning with the fourth week of training. In and ex vivo tibial strain experiments indicate that the repetitive mechanical loading during this time may not alone be sufficient to cause stress fracture. This has led to the hypothesis that the development of tibial stress fracture is mediated by the bone remodeling response to high repetitive strains. This study assesses the differences in the strain and angle of the principal strain during military field activities versus common civilian activities. MethodsIn vivo strain measurements were made from a rosette strain gauge bonded to the midshaft of the medial tibia. Measurements of principal strains and their angles were made while performing level and inclined walking and running on an asphalt surface, while fast walking up and down stairs, while performing a standing vertical jump and while zig-zag running up and down a 30° inclined dirt hill. FindingsThe angle of the principal strain varied little (5.40° to +2.74°) during activities performed on engineered surfaces. During zig-zag running on a dirt hill the strain levels were higher (maximum shear = 4290 με). At the pivot points of zig-zag running the angle of the principal strain varied between −115° to −123° downhill and between −32.8° to −51° uphill. InterpretationActivities that mimic those performed by infantry recruits on irregular hilly surfaces result in higher tibial strains and have more variation in principal strain angles than activities of ordinary civilian life performed on engineered surfaces.

Changes In Peak Accelerations And Shock Attenuation Over The Course Of A Marathon

Peak tibial and peak sacral accelerations have been shown to increase during a fatiguing run. Peak accelerations are often used as a surrogate for impacts on the body during running. High tibial impacts have been linked to development of tibial stress fractures. To understand how impacts are related to injury development, we need more insight in how shocks propagate through the body, especially under the influence of fatigue. PURPOSE: To investigate bilateral peak accelerations and shock attenuation over the course of a Marathon. METHODS: 5 trained athletes (2M 3F, 33.8±11.8 years, 182.3±5.8 cm, 73.9±9.1 kg years) ran a Marathon during competition. Inertial measurement units (240Hz) were placed on the sternum, pelvis, and bilaterally on the tibia and foot. Mean peak accelerations around initial contact and shock attenuation (% decrease of peak acceleration) were calculated over 25 strides during the 2nd and 42nd km of the Marathon. Paired sample t-tests were used to test for statistical differences between the 2nd and 42nd km and between the dominant and non-dominant side. RESULTS: See Table 1. Mean finish time was 4:07:40±0:19:07. CONCLUSION: Impacts and shock attenuation changed asymmetrically during a Marathon. Both side dominance and fatigue significantly influenced shock attenuation. However, on sternum level, only fatigue influenced impacts and shock attenuation, implying some sort of protective mechanism to keep proximal impacts low. The non-dominant side showed larger impacts during the whole Marathon, possibly because this side is less strong and therefore less able to actively (i.e. muscle contractions) absorb shocks. Overall, impacts increased and shock attenuation decreased towards the end of the Marathon, possibly increasing the risk of overuse injuries.

The role of acromial morphometry in the development of acromial stress fracture following reverse total shoulder arthroplasty.

Indications for reverse total shoulder arthroplasty are expanding, and postoperative acromial stress fractures are a troubling postoperative complication. The purpose of this study was to determine if differences in acromial morphometry were present between cohorts with and without this complication. A retrospective review of 101 reverse total shoulder arthroplasty procedures met criteria for the study. A total of eight acromial measurements on preoperative computed tomography scans were performed in axial, coronal, and sagittal views. Postoperative acromial stress fractures were confirmed by computed tomography scan on six patients and classified by fracture type. Statistical analysis was performed using a Mann-Whitney U test. The median acromial thickness at the posterior and lateral half was significantly thinner in the fracture cohort compared to the non-fracture cohort. Fracture and non-fracture cohort measurements demonstrated a median lateral thickness of 6.8 and 8.7 mm (p = 0.010), respectively, and median posterior thickness of 7.6 and 9.5 mm (p = 0.008), respectively. There were no demographic differences between cohorts. Two acromial measurements (lateral and posterior thickness) were associated with the development of postoperative acromial stress fracture following reverse total shoulder arthroplasty. These findings suggest that a thinner acromion in the lateral and posterior half is a risk factor for an acromial stress fracture following reverse total shoulder arthroplasty.

Tibial Stress Fracture Following Ankle Arthrodesis.

End-stage ankle arthritis is frequently treated with either tibiotalar or tibiotalocalcaneal (TTC) arthrodesis, but the inherent loss of accommodative motion increases mechanical load across the distal tibia. Rarely, patients can go on to develop a stress fracture of the distal tibia without any antecedent traumatic event. The purpose of this study was to determine the incidence of tibial stress fracture after ankle arthrodesis, highlight any related risk factors, and identify the effectiveness of treatment strategies and their healing potential. A retrospective chart review was performed at 2 large academic medical centers to identify patients who had undergone ankle arthrodesis and subsequently developed a stress fracture of the tibia. Any patient with a tibial stress fracture before ankle arthrodesis, or with a nontibial stress fracture, was excluded from the study. A total of 15 out of 1046 ankle fusion patients (1.4%) developed a tibial stress fracture at a mean time of 42 ± 82 months (range, 3-300 months) following the index procedure. The index procedure for these 15 patients who went on to subsequently develop stress fractures included isolated ankle arthrodesis (n = 8), ankle arthrodesis after successful subtalar fusion (n = 2), primary TTC arthrodesis (n = 2), and ankle arthrodesis subsequent to successful subtalar fusion with resultant ankle nonunion requiring revision TTC nailing (n = 3). Four patients had undergone fibular osteotomy with subsequent onlay strut fusion, and 5 had undergone complete resection of the lateral malleolus. Stress fracture location was found to be at the level of the fibular osteotomy in 2 patients and at the proximal end of an existing or removed implant in 9. Fourteen of the 15 patients had a nondisplaced stress fracture and were initially treated with immobilization and activity modification. Of these, 3 failed to improve with nonoperative treatment and subsequently underwent operative fixation (intramedullary nail in 2; plate fixation in 1). Only 1 of the 15 patients presented with a displaced fracture and underwent immediate plate fixation. All patients reported pain improvement and were ultimately healed at final follow-up. In this case series review, we found a 1.4% incidence of tibial stress fracture after ankle arthrodesis, and both hardware transition points and a fibular resection or osteotomy appear to be risk factors. Operative intervention was required in approximately 25% of this population, but the majority of tibial stress fractures following ankle fusion were successfully treated nonoperatively, and ultimately all healed. Level IV, retrospective case series.

The effects of methylphenidate on stress fractures in patients' ages 10–29: a national database study

ABSTRACT Objectives: Current literature is divided on the effect of methylphenidate (MP) on stress fracture development and if this medication increases fracture, or is actually protective for it. This study further investigates this effect utilizing a large national database. We hypothesized that individuals on MP would have a reduced risk of SF compared against controls. Methods: This study utilized the Humana insurance data set within the PearlDiver Patient Records Database (PearlDiver Inc, Fort Wayne, Indiana). All patients’ ages 10–29 were included and patients were identified without ADHD, with ADHD not on MP, and with ADHD on MP. ADHD and stress fracture diagnoses were identified by International Classification of Disease, Tenth Revision codes. Bivariate analysis of stress fracture occurrence was conducted using chi-square analysis. Multivariate logistic regression was used to calculate odds ratios, controlling for age, sex, race, and Charlson Comorbidity Index (CCI). Statistical analysis was performed using the PearlDiver software, which runs R, Version 1.1.442. An α value of .05 was set as the level of significance. Results: The study included 29,590 patients on MP and 831,439 patients not on MP from ages 10–29. The highest proportions of patients who filled MP prescriptions were in the age range 10 to 14 years old (51.2%), followed by 15 to 19 (41.0%). Patients rarely continue MP from years 20 to 24 (16.5%) or 25 to 29 (9.6%). ADHD patients on MP had the lowest calculated risk of stress fractures (0.45%) compared to patients without ADHD (0.54%) and ADHD patients not on methylphenidate (0.58%). In all three patient groups, most stress fractures occurred in 15 to 19-year olds. Patients with ADHD on MP conferred lower odds of stress fracture than ADHD patients not on MP and patients without ADHD (aOR = 0.64, p = 0.0002). The older age groups 20–24 and 25–29 involved less risk of stress fracture compared to the youngest age group 10–14 (p < 0.0001; p < 0.0001), as well as did male gender (p < 0.0001). Conclusions: This database-based study of the effect of MP on SF adds to the growing body of literature providing evidence that MP may offer protective benefit for stress fracture.