Incidence Of Stress Fractures Research Articles

Influence of professional sports activities on bone mineral density (<i>literature review</i>)

Introduction. The positive effect of physical activity on the state of bone has been proven by many researchers. Professional sports activity is a model of the constant impact of physical activity on the human body, acting as the most powerful mechanism for activating and mobilizing the functional reserves of an athlete, which, against the background of a progressive increase in the volume, intensity and duration of exposure, shows an increase in the incidence of injuries and stress fractures, one of the leading causes of which is a decrease in bone mineral density (BMD) up to the development of osteoporosis. The risk factors for the development of the pathology of the musculoskeletal system, which have a direct impact on the formation of the BMD, in elite sports include the volume and intensity of training loads, the stereotype of the main competitive exercise, the daily balance of energy intake.The aim is to study is to analyze modern scientific publications on the impact of professional sports activities on bone mineral density.Materials and methods. The review is based on publications from the PubMed, Google Scholar, Cyberleninka, eLIBRARY databases. Preference was given to articles published in refereed sources over the past 10 years.Results. The specificity of the main competitive exercise determines the presence of asymmetry in the distribution of the BMD in athletes, in addition, the level of BMD is higher in the leading limb compared to the opposite. Increasing the qualifications, experience and age of an athlete shows a positive impact on the performance of the BMD, with the exception of certain specializations. A different effect of sports with a high osteogenic effect of shock and weight load on the state of the BMD was noted compared to the general population. Power athletes, combat and game sports athletes have higher levels BMD compared to representatives of cycling, swimming, rowing, triathlon and long-distance running, characterized by the limitation of gravitational (shock) load or a large amount of low-intensity training exposure. Lower BMD were noted in athletes in sports specializations with weight categories, aesthetic and cyclic sports, where the problem of a relative energy deficiency in sport, which negatively affects bone metabolism.Conclusions. In athletes, the volume and intensity of training loads, the stereotype of performing the main competitive exercise, the daily balance of energy intake have a direct impact on the formation of the BMD with the allocation of risk groups for the pathology of the musculoskeletal system in elite sports.

Effects of added trunk load on the in vivo kinematics of talocrural and subtalar joints during landing

BackgroundLanding from heights is a common movement for active-duty military personnel during training. And the additional load they carry while performing these tasks can affect the kinetics and ankle kinematic of the landing. Traditional motion capture techniques are limited in accurately capturing the in vivo kinematics of the talus. This study aims to investigate the effect of additional trunk load on the kinematics of the talocrural and subtalar joints during landing, using a dual fluoroscopic imaging system (DFIS). MethodsFourteen healthy male participants were recruited. Magnetic resonance imaging was performed on the right ankle of each participant to create three-dimensional (3D) models of the talus, tibia, and calcaneus. High-speed DFIS was used to capture the images of participants performing single-leg landing jumps from a height of 40 cm. A weighted vest was used to apply additional load, with a weight of 16 kg. Fluoroscopic images were acquired with or without additional loading condition. Kinematic data were obtained by importing the DFIS data and the 3D models in virtual environment software for 2D–3D registration. The kinematics and kinetics were compared between with or without additional loading conditions. ResultsDuring added trunk loading condition, the medial-lateral translation range of motion (ROM) at the talocrural joint significantly increased (p < 0.05). The subtalar joint showed more extension at 44–56 ms (p < 0.05) after contact. The subtalar joint was more eversion at 40–48 ms (p < 0.05) after contact under the added trunk load condition. The peak vertical ground reaction force (vGRF) significantly increased (p < 0.05). ConclusionsWith the added trunk load, there is a significant increase in peak vGRF during landing. The medial-lateral translation ROM of the talocrural joint increases. And the kinematics of the subtalar joint are affected. The observed biomechanical changes may be associated with the high incidence of stress fractures in training with added load.

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.

Amenorrhea and Stress Fractures in Female New Jersey Division III Collegiate Runners: An Opportunity for Increased Health Education

BACKGROUND: In the National Collegiate Athletic Association (NCAA), 9.1% of the injuries reported by women’s cross-country athletes between 2014-2019 were fractures. Both history of amenorrhea and prior stress fractures have been found to predict incidence of subsequent bone stress injuries among female athletes. Although excessive exercise is a major contributor to the development of amenorrhea, there are currently no studies on the association between amenorrhea and stress fractures in New Jersey (NJ) National NCAA Division III Women’s cross country or track athletes. This study aims to determine if there is an association between incidence of amenorrhea and subsequent occurrence of stress fractures among this population, and to identify a possible area for increased reproductive health education. METHODS: This is a survey-based study. Participants were female athletes over the age of 18 who currently participate in collegiate cross country or track running at a NJ Division III school. Coaches of the Division III cross country and track teams in NJ distributed a survey to their female athletes to gain participants for this study. Survey data included information on participant menstrual history, stress fracture history, and athletic involvement. Participants also indicated if their school’s staff had ever educated them on the importance of menstrual regularity and athletics. Descriptive statistics and comparison between groups were analyzed. RESULTS: In total, 68 survey responses were collected. Survey respondents included female NJ cross country and track athletes ages 18-23, from a total of eight institutions. During training or competition, 58.8% of the study participants missed at least one menstrual cycle and 45.6% experienced a stress fracture. There is a significant association between having missed at least one menstrual cycle during training or competition and the number of stress fractures experienced by the athlete (p = 0.044). Only 30.9% of respondents indicated that someone from their school’s staff spoke to them about the importance of maintaining regular menstruation during training. CONCLUSION: This study confirms that both amenorrhea and stress fractures are commonly seen among NJ NCAA Division III female cross country and track athletes. Our data also highlights a need for increased education of NJ Division III female athletes regarding the importance of maintaining regular menstruation as a means of stress fracture prevention. Further investigation of the role of amenorrhea on the incidence of stress fractures may shine light on an important area for prevention and increased health education.

Cumulative Incidence of All-Cause Knee Injury, Concussion, and Stress Fracture among Transgender Patients on Gender-Affirming Hormone Therapy: An Exploratory Retrospective Cohort Study.

Previous research has shown a discrepancy in incidences of knee injuries, stress fractures, and concussions between cisgender men and women. Little is known regarding the incidence of musculoskeletal injuries among patients on gender-affirming hormone therapy (GAHT). This retrospective cohort study examines cumulative incidence of knee injuries, concussions, and stress fracture injuries among transgender patients on GAHT at one health system from 2011-2020. Using relevant ICD-9 and 10 codes, incidences of knee injury, concussion, and stress fracture were calculated. Cohorts included 1971 transgender and 3964 cisgender patients. Transgender patients had significantly higher incidence of all-cause knee injuries over the study period, 109 (5.5%) versus 175 (4.4%) (p < 0.001; OR: 2.14, 95% CI [1.17-3.92]). Subgroup analysis showed significantly higher incidence of knee injuries among cisgender men (5.6%) versus cisgender women (4.1%) (p = 0.042) and among transgender women (6.6%) versus cisgender women (4.1%) (p = 0.005). There were no significant differences between incidences of concussion and stress fracture between groups. This sample showed that patients on GAHT had increased cumulative incidences of all-cause knee injury compared to controls but similar cumulative incidences of concussion and bone-stress injuries. Transgender women on exogenous estrogen had significantly higher cumulative incidences of all-cause knee injuries compared to cisgender women.

Concomitant open distal clavicle excision is associated with greater improvement in range of motion without increased risk of acromial stress fracture after reverse total shoulder arthroplasty: a retrospective cohort study.

The purpose of this study was to evaluate the effect of concomitant open distal clavicle excision (DCE) on postoperative clinical outcomes and incidence of acromial and scapular stress fractures (ASFs) in patients with symptomatic acromioclavicular joint osteoarthritis (ACJ OA) undergoing reverse total shoulder arthroplasty (RTSA). A single-surgeon retrospective cohort study was conducted including patients who underwent primary elective RTSA with or without DCE from 2015 to 2019 with a minimum 6-month follow-up period. Shoulder active range of motion (AROM) and visual analog scale (VAS) pain were recorded preoperatively and postoperatively. ASFs and other adverse events were identified using postoperative notes and/or radiographs. Characteristics and outcomes were compared between the RTSA and RTSA-DCE groups. Forty-six RTSA patients (mean age, 67.9±8.7 years; 60.9% male; mean follow-up, 24.9±16.6 months) and 70 RTSA-DCE patients (mean age, 70.2±8.9 years; 20.0% male; mean follow-up, 22.7±12.9 months) were included. There were no significant intergroup differences in rates of ASF (RTSA, 0.0% vs. RTSA-DCE, 1.4%; P=1.00), stress reactions (RTSA, 8.7% vs. RTSA-DCE, 11.4%; P=0.76), reoperation, revision, or infection (all P>0.05), or in pre-to-postoperative reduction in VAS pain (P=0.17) at latest follow-up. However, the RTSA-DCE group had greater pre-to-postoperative improvement in flexion AROM (RTSA, 43.7°±38.5° vs. RTSA-DCE, 59.5°±33.4°; P=0.03) and internal rotation (IR) AROM (P=0.02) at latest follow-up. Concomitant DCE in RTSA improves shoulder flexion and IR AROM, alleviates shoulder pain, and does not increase the risk of ASFs. Level of evidence: III.

Changes in the incidence of stress reactions and fractures among intercollegiate athletes after the COVID-19 pandemic

PurposeThe purpose of this study was to characterize the impact of detraining due to the COVID-19 pandemic on incidence of bony injuries and stress fractures in collegiate athletes.MethodsA comprehensive collegiate athletic conference injury database was queried for all in-season, sport-related bony injuries (defined as all stress reactions and fractures) that occurred across all sports from January 2016 to June 2021. The bony injury rate per 1000 athlete exposure hours (AEH) was calculated and compared between the immediate post-hiatus season and historic rates from pre-hiatus seasons (2016–2019). Injury characteristics were also compared between the pre- and post-hiatus time periods.ResultsA total of 868 bony injuries across 23 sports were identified. The sports with highest overall baseline bony injury rates in historic seasons were women’s cross country (0.57 injuries per 1000 AEH) and men’s cross country (0.32). Compared to historic pre-hiatus rates, female cross-country runners demonstrated a significantly lower bony injury incidence rate in the post-hiatus season (0.24 vs. 0.57, p = 0.016) while male swimming athletes demonstrated a statistically significant increase in bony injury rate (0.09 vs. 0.01, p = 0.015). The proportion of bony injuries attributed to repetitive trauma increased; while, the proportion of injuries attributed to running decreased between the pre- and post-hiatus seasons.ConclusionAcross all sports, there was no consistent trend toward increased rates of bony injury in the immediate post-hiatus season. However, female cross-country runners demonstrated lower rates of bony injury in the post-hiatus season while male swimmers demonstrated higher rates. Furthermore, bony injuries in the post-hiatus season were more likely to be the result of repetitive trauma and less likely to be from running.Level of Evidence: Level III, retrospective, cross sectional study.

Effect of stride length on the running biomechanics of healthy women of different statures.

Tibial stress fracture is a debilitating musculoskeletal injury that diminishes the physical performance of individuals who engage in high-volume running, including Service members during basic combat training (BCT) and recreational athletes. While several studies have shown that reducing stride length decreases musculoskeletal loads and the potential risk of tibial injury, we do not know whether stride-length reduction affects individuals of varying stature differently. We investigated the effects of reducing the running stride length on the biomechanics of the lower extremity of young, healthy women of different statures. Using individualized musculoskeletal and finite-element models of women of short (N = 6), medium (N = 7), and tall (N = 7) statures, we computed the joint kinematics and kinetics at the lower extremity and tibial strain for each participant as they ran on a treadmill at 3.0m/s with their preferred stride length and with a stride length reduced by 10%. Using a probabilistic model, we estimated the stress-fracture risk for running regimens representative of U.S. Army Soldiers during BCT and recreational athletes training for a marathon. When study participants reduced their stride length by 10%, the joint kinetics, kinematics, tibial strain, and stress-fracture risk were not significantly different among the three stature groups. Compared to the preferred stride length, a 10% reduction in stride length significantly decreased peak hip (p = 0.002) and knee (p < 0.001) flexion angles during the stance phase. In addition, it significantly decreased the peak hip adduction (p = 0.013), hip internal rotation (p = 0.004), knee extension (p = 0.012), and ankle plantar flexion (p = 0.026) moments, as well as the hip, knee, and ankle joint reaction forces (p < 0.001) and tibial strain (p < 0.001). Finally, for the simulated regimens, reducing the stride length decreased the relative risk of stress fracture by as much as 96%. Our results show that reducing stride length by 10% decreases musculoskeletal loads, tibial strain, and stress-fracture risk, regardless of stature. We also observed large between-subject variability, which supports the development of individualized training strategies to decrease the incidence of stress fracture.

Incidence, risk factors, and complications of acromial stress fractures after reverse total shoulder arthroplasty

An acromial stress fracture (ASF) is an uncommon complication after reverse total shoulder arthroplasty (RTSA) that can have severe clinical consequences on shoulder function. Although patient-specific factors have been identified to influence the risk of ASFs, it is unclear whether modifying these factors can minimize risk. Moreover, there is limited information on the treatment outcomes of these fractures. Therefore, the purpose of this study was to determine modifiable risk factors of ASFs and the complication and revision rates of conservatively and operatively managed ASFs. The PearlDiver database was queried to identify a cohort of patients who underwent RTSA with minimum 2-year follow-up. Current Procedural Terminology (CPT) and International Classification of Diseases (ICD) codes were used to compare the demographics, comorbidities, and medication use of patients with and without ASFs. Surgical complication and revision rates were compared between operatively and conservatively treated fractures. The overall incidence of ASFs was 1.4%. Patient-specific factors that were independently associated with the occurrence of an ASF included osteoporosis, rheumatologic disease, shoulder corticosteroid injection within 3 months before surgery, and chronic oral corticosteroid use. Among patients with osteoporosis, the initiation of physical therapy within 6 weeks after surgery also increased the risk of ASF. Patients who underwent surgical treatment of ASFs had a revision arthroplasty rate of 7.0% compared to a rate of 3.2% among those with conservatively managed fractures. ASFs are an infrequent complication that can occur after RTSA. Preoperative factors that affect the quality of bone independently increase the fracture risk. Moreover, this risk can be minimized by avoiding shoulder corticosteroid injections 3 months before surgery and delaying physical therapy exercises among patients with osteoporosis. Surgical fixation of these fractures should be reserved to instances when conservative management has failed given high rates of infection, instability, and revision shoulder arthroplasty.

Clinical and Radiological Outcomes in Lateralized versus Non-lateralized and Distalized Glenospheres in Reverse Total Shoulder Arthroplasty: A Randomized Control Trial.

Lateralization in reverse total shoulder arthroplasty (RTSA) has been used to theoretically offer the potential benefits of reduced scapular notching rates and improved stability and range of motion (ROM), particularly external rotation. The aim of this study was to compare ROM, clinical and radiographic outcomes between patients who underwent RTSA with a lateralized versus a non-lateralized and distalized glenosphere. A single surgeon randomized control trial was conducted comparing 27 patients with a lateralized glenosphere and 26 patients with a non-lateralized and distalized glenosphere. 66 patients were enrolled, two patients died prior to two-year follow-up, four patients withdrew from the study and seven patients were lost to follow-up. All patients in the lateralized group received 6 mm of lateralization through the glenosphere. Participants represented a population presenting to an orthopedics sports medicine clinic with any indication for RTSA including revision arthroplasty. Patients completed preoperative and routine postoperative functional outcome measures 3, 6, 12, and a minimum of 24 months postoperatively including American Shoulder and Elbow Surgeons (ASES), Patient-Reported Outcomes Measurement Information System Physical Function Upper Extremity (PROMIS PF UE) and Activities of Daily Living Requiring Active External and Internal Rotation (ADLEIR) assessments. Patients were also evaluated with ROM and radiographic measurements. The primary outcome of interest in this study was ROM, particularly external rotation. At two-year follow-up, both groups had significant improvement in their ASES, PROMIS PF UE and ADLEIR scores with no significant difference observed between groups. There were no statistically significant differences in incidence of scapular notching or acromial stress fractures. ROM in both groups improved significantly at their two-year assessment with the only exception to this being external rotation at 90° of abduction in the non-lateralized and distalized group (39° ± 31° versus 48° ± 24°, p=0.379). Regardless of glenosphere lateralization status, patients in both groups had significant improvement in functional outcome scores and ROM and there were no significant differences observed between groups at two-year follow-up. Longer follow-up is needed to determine the effect of implant design on late complications, long-term outcomes and implant retention.

The Impact of Covid-19 Pandemic Restrictions on the Incidence of Stress Reactions and Fractures Among Division 1 NCAA Athletes

The Impact of Covid-19 Pandemic Restrictions on the Incidence of Stress Reactions and Fractures Among Division 1 NCAA Athletes

Enforcing walking speed and step-length affects joint kinematics and kinetics in male and female healthy adults

BackgroundIndividuals increase walking speed by increasing their step-length, increasing their step-frequency, or both. During basic training military recruits are introduced to marching “in-step”, and thus the requirement to walk at fixed speeds and step-lengths. The extent to which individuals are required to under- or over-stride will vary depending on their stature, and the stature of others in their section. The incidence of stress fractures in female recruits undergoing basic training is higher than that for their male counterparts. Research question:Therefore, the purpose of this study was to determine how joint kinematics and kinetics are affected by walking speed, step-length, and sex. MethodsThirty-seven (19 female) aerobically active non-injured individuals volunteered for this study. Synchronised three-dimensional kinematic and kinetic data were collected while participants walked overground at prescribed speeds. Audio and visual cues were used to control step-lengths. Linear mixed models were run to analyse the effects of speed, step-length condition, and sex on peak joint moments. Results and SignificanceThe findings of this study showed that, in general, walking faster and over-striding predominantly increased peak joint moments, suggesting that over-striding is more likely to negatively affect injury risk than under-striding. This is especially important for individuals unaccustomed to over-striding as the cumulative effect of increased joint moments may affect a muscles capability to withstand the increased external forces associated with walking faster and with longer step-lengths, which could then lead to an increased risk of developing an injury.

Clinical outcomes after reverse shoulder arthroplasty in patients 60 years old and younger; medium-term results

Reverse total shoulder arthroplasty (RTSA) has been well-described as a surgical solution to manage rotator cuff tear arthropathy in elderly, low demand paitents. As experience has increased along with improvements in technique and implant design, RTSA has become increasingly used to manage more varied pathologic conditions of the shoulder in younger, more active patients. This study evaluates outcomes in a consecutive series of patients aged 60 years old and younger after undergoing RTSA. There were 94 shoulders in 89 patients enrolled. Mean age of the cohort was 54.8 (range 18-60 years). Surgical indications included rotator cuff tear arthropathy, irreparable rotator cuff tear without arthritis, glenohumeral arthritis with erosive glenoid deformity, inflammatory arthropathy, proximal humerus fracture nonunion/malunion and failed prior shoulder arthroplasty. Sixty-one shoulders (70%) had undergone at least one prior surgery. Of these, 6 shoulders (6% of total cohort) had a prior failed arthroplasty. Clinical outcomes (American Shoulder and Elbow Surgeons score, Western Ontario Osteoarthritis of the Shoulder index; visual analog scale pain), radiographic outcomes and complications were analyzed and assessed for correlation with patient demographic factors. The mean follow-up for this cohort was 4.9 years (range 2-12 years). Subjects experienced improvements in ASES score and pain (P<.001) and active forward elevation (88° preop to 135° postop, P<.001). Prior operation correlated with worse postoperative ASES and WOOS scores. Higher demand occupation correlated with less improvement in pain scores. The overall complication rate was 12%. Seven shoulders (7%) underwent an additional procedure. There was a 2% incidence of dislocation and a 4% incidence of acromial stress fracture. There was a 36% incidence of notching. With medium-term follow-up, RTSA is a reliable and predictable operation to manage various pathologic conditions in patients aged 60 years or less. Patients predictably experience significant improvements in pain and range of motion while assuming a modest complication risk. Long-term study is needed to understand potential for late complications or implant failure.

How Advancement in Bone Science Should Inform the Examination and Treatment of Femoral Shaft Bone Stress Injuries in Running Athletes.

Stress fractures likely have a 1-2% incidence in athletes in general. In runners, a more vulnerable population, incidence rates likely range between 3.2 and 21% with female runners having greater susceptibility. The incidence of femoral shaft stress fractures is less well known. New basic and translational science research may impact the way clinicians diagnose and treat femoral stress fractures. By using a fictitious case study, this paper applies bone science to suggest new approaches to evaluating and treating femoral shaft stress fractures in the running population.

Lower Extremity Stress Fractures in the National Basketball Association, 2013-2014 Through 2018-2019.

Background:Players in the National Basketball Association (NBA) are at risk for lower extremity stress fractures, partly because of the sport’s high-intensity demand on the lower body.Purpose:To provide insight on the identification and management of potential risk factors associated with lower extremity stress fractures in NBA athletes.Study Design:Case series; Level of evidence, 4.Methods:A retrospective study was conducted using the NBA electronic medical record database for all players who were on an NBA roster for ≥1 game from the 2013-2014 through 2018-2019 seasons. Player characteristics, games missed, and treatment methodology were independently analyzed. Results were presented as incidence per 1000 player-games.Results:There were 22 stress fractures identified in 20 NBA players over the course of 6 years, with an average of 3.67 stress fractures per year and an incidence of 0.12 stress fractures per 1000 player-games. Most stress fractures occurred in the foot (17/22), and 45% (10/22) of stress fractures were treated surgically, with the most common site of operation being the navicular. On average, approximately 37 games and 243 days were missed per stress fracture injury. There was no significant difference in time to return to play between high-risk stress fractures treated operatively versus nonoperatively (269.2 vs 243.8 days; P = .82).Conclusion:The overall incidence of stress fractures in NBA players was 0.12 per 1000 player-games, and a high percentage of players returned to NBA activity after the injury. There was a relatively even distribution between high-risk stress fractures treated operatively and nonoperatively. When comparing high-risk stress fractures treated operatively to ones treated nonoperatively, no significant difference in average time to return to play in the NBA was found.

The incidence and risk factors for stress fracture following periacetabular osteotomy.

The aims of this study were to characterize the incidence and risk factors associated with stress fractures following periacetabular osteotomy, and to determine their effect on osteotomy union. We retrospectively reviewed all periacetabular osteotomies (PAOs) performed for developmental dysplasia of the hip (DDH) at one institution over a six-year period between 2012 and 2017. Perioperative factors were recorded, and included demographic and surgical data. Postoperatively, patients were followed for a minimum of one year with anteroposterior and false profile radiographs of the pelvis to monitor for evidence of stress fracture and union of osteotomies. We characterized the incidence and locations of stress fractures, and used univariate and multivariable analysis to identify factors predictive of stress fracture and the association of stress fracture on osteotomy union. A total of 331 patients underwent PAO during the study period with 56 (15.4%) stress fractures: 46 fractures of the retroacetabular posterior column, five cases of ischiopubic stress fracture, and five cases of concurrent ischiopubic and retroacetabular stress fractures. Overall, 86% (48/56) healed without intervention. Univariate analysis revealed that stress fractures occurred more frequently in females (p = 0.040), older patients (mean age 27.6 years (SD 8.4) vs 23.8 (SD 9.0); p = 0.003), and most often with the use of the broad Mast chisel (28.5%; p < 0.001). Multivariable analysis revealed that increasing age (odds ratio (OR) 1.04; 95% CI 1.01 to 1.07; p = 0.028) and use of the broad Mast chisel (OR 5.1 (95% CI 1.3 to 19.0) compared to narrow Ganz chisel; p = 0.038) and surgeon (p = 0.043) were associated with increased risk of stress fracture. Patients with stress fractures were less likely to have healed osteotomies after one-year follow-up (76% vs 96%; p < 0.001). Stress fracture of the posterior column may be an under-recognized complication following PAO, and the rate may be influenced by surgical technique. Consideration should be given to using a narrow chisel during the ischial cut to reduce the risk of stress propagation through the posterior column.Cite this article: Bone Joint J2022;104-B(9):1017-1024.

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

In vivo strains at the middle and distal thirds of the tibia during exertional activities

There is a known variance in the incidence and anatomical site of tibial stress fractures among infantry recruits and athletes who train according to established uniform training programs. To better understand the biomechanical basis for this variance, we conducted in vivo axial strain measurements using instrumented bone staples affixed in the medial cortex, aligned along the long axis of the tibia at the level of the mid and distal third of the bone in four male subjects. Strain measurements were made during treadmill walking, treadmill running, drop jumps from a 45 cm height onto a force plate and serial vertical jumps on a force plate. Significance levels for the main effects of location, type of activity and their interaction were determined by quasi-parametric methodologies. Compared to walking, running and vertical jumping peak axial tensile strain (με) was 1.94 (p = 0.009) and 3.92 times (p < 0.001) higher, respectively. Peak axial compression strain (με) values were found to be greater at the distal third than at the mid tibia for walking, running and vertical jumping (PR = 1.95, p-value<0.001). Peak axial compression and tension strains varied significantly between the subjects (all with p < 0.001), after controlling for strain gauge location and activity type.The study findings help explain the variance in the anatomical location of tibial stress fractures among participants doing the same uniform training and offers evidence of individual biomechanical susceptibility to tibial stress fracture. The study data can provide guidance when developing a generalized finite element model for mechanical tibial loading. For subject specific decisions, individualized musculoskeletal finite element models may be necessary.

Once daily calcium (1000mg) and vitamin D (1000IU) supplementation during military training prevents increases in biochemical markers of bone resorption but does not affect tibial microarchitecture in Army recruits.

Basic combat training (BCT) is a period of novel physical training including load carriage resulting in higher risk of stress fracture compared to any other time during military service. Prior trials reported a 20% reduction in stress fracture incidence with Ca and vitamin D (Ca+D) supplementation (2000mg Ca, 800IU vitamin D), and greater increases in tibia vBMD during BCT compared to placebo. The primary objective of this randomized, double-blind, placebo-controlled trial was to determine the efficacy of a lower dose of Ca (1000mg/d Ca, 1000IU vit D) on PTH, bone biomarkers and tibial microarchitecture during BCT. One hundred volunteers (50 males, 50 females; mean age 21.8±3.5 y) were block randomized by race and sex to receive a daily Ca+D fortified food bar or placebo. Anthropometrics, dietary intake, fasted blood draws and high resolution pQCT scans of the distal and mid-shaft tibia were obtained at the start of BCT and 8 wks later at the conclusion of training. As compliance was 98% in both treatment groups, an intent-to-treat analysis was used. At the distal tibia, total vBMD, Tb.vBMD, Tb.N, Th.Th and Tb.BV/TV increased (+1.07 to 2.12% for all, p<0.05) and Tb.Sp decreased (0.96 to 1.09%, p<0.05) in both treatment groups. At the mid-shaft, Ct.Pm increased (+0.18 to 0.21%, p=0.01) and Ct.vBMD decreased (-0.48 to -0.77%, p<0.001) in both groups. Ca+D prevented increases in CTX and TRAP, which were observed in the placebo group (group-by-time, p<0.05). Mean circulating 25OHD, BAP, P1NP and iCa increased and PTH decreased in both treatment groups (p<0.05). These results, in agreement with other studies, suggest that bone microarchitectural changes indicative of bone formation occur during BCT. While Ca+D supplementation at lower doses than those tested in previous studies prevented increases in biochemical markers of bone resorption in this study, there were no significant changes in bone tissue after 8 wks of Army BCT.

Non-Modifiable Risk Factors for Stress Fractures in Military Personnel Undergoing Training: A Systematic Review.

A fracture, being an acquired rupture or break of the bone, is a significant and debilitating injury commonly seen among athletes and military personnel. Stress fractures, which have a repetitive stress aetiology, are highly prevalent among military populations, especially those undergoing training. The primary aim of this review is to identify non-modifiable risk factors for stress fractures in military personnel undergoing training. A systematic search was conducted of three major databases to identify studies that explored risk factors for stress fractures in military trainees. Critical appraisal, data extraction, and a narrative synthesis were conducted. Sixteen articles met the eligibility criteria for the study. Key non-modifiable risk factors identified were prior stress fracture and menstrual dysfunction, while advancing age and race other than black race may be a risk factor. To reduce the incidence of stress fractures in military trainees, mitigating modifiable risk factors among individuals with non-modifiable risk factors (e.g., optimising conditioning for older trainees) or better accommodating non-modifiable factors (for example, extending training periods and reducing intensity to facilitate recovery and adaptation) are suggested, with focus on groups at increased risk identified in this review.