The comprehensive description of stress fractures: a new classification system

Bone Stress Injury Epidemiology and Risk Factors in Female Off-Road Runners: A Systematic Review

BACKGROUND

Off-road running is a growing sport with little research investigating injury profiles of female participants. Bone stress injuries (BSIs) are a particularly detrimental injury with little known about their incidence and risk factors in female off-road runners.

OBJECTIVE

Collate and review the available evidence reporting epidemiological data and risk factors associated with BSI in female off-road runners.

DESIGN

Systematic literature review, without meta-analyses.

DATA SOURCES

MEDLINE OVID, PubMed, SPORTDiscus, and MEDLINE EBSCO. Searches were finalized in July 2024.

ELIGIBILITY CRITERIA

Studies that reported injury surveillance statistics and/or risk factors associated with BSIs in female off-road runners.

RESULTS

Seventeen eligible studies were included, of which all reported surveillance statistics and 2 reported risk factors associated with BSI among 897 female runners. Owing to the scarcity of data, cross-country runners were included in the population of off-road runners. Most BSIs were high severity and in the lower leg, with an overall incidence ranging from 0 to 34.39 BSIs per 100,000 athlete-exposures and prevalence ranging from 0% to 40.9%. Study characteristics were reported alongside risk of bias, quality, and level of evidence assessment outcomes from varying tools. Eight significant intrinsic risk factors were associated with BSIs in female off-road runners: increasing age, disrupted menstruation, previous BSI, increased female triad risk, and lower calcium, vitamin D, and calorie intake.

DISCUSSION

Limited by the number of studies available reporting data on the specific target population, which highlights the need for performing high-quality prospective studies in the future, this review summarizes the current epidemiological data and risk factors associated with BSIs in female off-road runners.

International Delphi consensus on bone stress injuries in athletes

Bone stress injuries, commonly referred to as stress reactions and stress fractures, represent overuse injuries to bone. These injuries result in physical limitations in activity and can be career-ending for high-level athletes. While bone stress injuries have received increased attention in recent years, international consensus is lacking on definitions, risk factors and strategies for management and prevention. This study aimed to ascertain and improve the level of agreement on bone stress injuries by utilising a three-part modified Delphi approach on (1) pathophysiology, diagnosis, terminology and classification systems; (2) risk factors, screening and prevention; and (3) management and return to sport. A multidisciplinary steering committee initiated the consensus process. A panel of 41 members from six continents was formed to complete three rounds of voting, including experts (scientists and clinicians) and representatives (athletes and coaches). Thirty-three, 28 and 28 panel members completed Delphi rounds 1, 2 and 3, respectively. Consensus was reached on 41 out of 58 statements. Findings from this Delphi study outline a multifactorial approach to identify and manage bone stress injuries and to promote bone health in athletes. This includes recommendations for diagnostic workup and treatment to assist clinicians in caring for patients with bone stress injuries. Finally, this consensus process identifies knowledge gaps and provides a framework for future research to advance the clinical care and prevention of bone stress injuries.

Relative Energy Deficiency in Sport (RED-S) and Goldman's Dilemma: A Case Report in 42 Year-Old Woman Endurance Athlete

Relative Energy Deficiency in Sport (RED-S) defines insufficient calorie intake for the physiological and athletic functions of the athlete, and accordingly deterioration in the musculoskeletal, hormonal, cardiovascular and immune systems. Herein, we present a 42-year-old female long-distance runner with multiple pelvic stress fractures who didn't complete her prescribed treatment program and wanted to keep running despite being aware of the associated pain and risks. The Goldman dilemma refers to the unsettling reality that a significant number of professional athletes may contemplate sacrificing their lives in order to achieve Olympic glory. This disregard for the numerous challenges stemming from an obsession with success is equally applicable to the amateur athlete depicted in this case. Our patient's fractures were examined in relation to RED-S and managed through conservative treatment methods. The RED-S and Goldman dilemma should be kept in mind not only in professional but also in semi-professional, and amateur athletes.

Spondylolysis and Spondylolisthesis in Athletes

This article is an update on spondylolysis and spondylolisthesis in athletes, from diagnosis to treatment, based on our service experience and a literature review.

[Sacral H-shaped fractures between traumatic, insufficiency and fatigue fractures : Similarities, differences and controversies]

In the basic entirety of stress fractures, insufficiency fractures are defined as fractures caused by prolonged normal or physiological loading of a bone with insufficient elastic resistance. This clearly distinguishes it from fatigue fractures, in which excessive loads are continuously applied to a bone with normal elastic resistance. According to Pentecost (1964) both entities of stress fracture result from "the inherent inability of the bone to withstand stress applied without violence in a rhythmical, repeated, subthreshold manner". This distinguishes them from acute traumatic fractures. In the clinical routine these differences are not always so clearly presented. The example of the H‑shaped sacral fracture is used to illustrate the relevance of a clear terminology. In this context, current controversies in the treatment of sacral insufficiency fractures are discussed.

Initial Experience With Subchondral Stabilization for Grade II Stress Fractures of the Midfoot and Forefoot

Stress fractures of the foot are often preceded by magnetic resonance imaging evidence of bone marrow edema. While new evidence suggests intraosseous injection of calcium phosphate ("subchondral stabilization") can alleviate symptoms associated with bone marrow edema, no data yet exist regarding its use in developing mid- and forefoot stress fractures. Fifty-four patients who underwent subchondral stabilization of various midfoot/forefoot bones in our practice were observed over a 5-year period. All patients were unresponsive to standard nonoperative measures for at least 6 weeks, and all had clinical exams and advanced imaging consistent with a Kaeding-Miller Grade II stress fracture. Forty patients were included with a mean age of 54.3 ± 14.9 years and mean follow-up of 14.1 ± 6.9 months. Patients saw a significant decrease in visual analog scale (VAS) pain as early as 1 month postoperatively (p < .05). Mean postoperative VAS at 12 months was 2.11 ± 2.50, and mean reduction in VAS pain from preoperative to 12 months postoperative was -5.00 (95% CI -3.44 to -6.56, p < .05). Fourteen patients (34%, 14/41) were entirely pain free at 12 months. Higher preoperative VAS pain scores (unadjusted odds ratio [OR] 2.13 [95% CI 1.20-3.77], p = .010) and treatment of more than 1 bone (unadjusted OR 6.23 [95% CI 1.39-27.8], p = .017) were associated with a greater likelihood of not achieving a pain free status at 12 months. Our initial experience with subchondral stabilization suggests the procedure may be safe and effective for use in many Kaeding-Miller Grade II stress fractures of the mid- and forefoot.

Bone Stress Injuries at the Ankle and Foot

Bone stress injuries (BSIs) are a frequent finding in athletes, particularly of the foot and ankle. A BSI is caused by recurring microtrauma to the cortical or trabecular bone exceeding the repair capacity of normal bone. The most frequent fractures at the ankle are low risk, characterized by a low risk for nonunion. These include the posteromedial tibia, the calcaneus, and the metatarsal diaphysis. High-risk stress fractures have a higher risk for nonunion and need more aggressive treatment. Examples are the medial malleolus, navicular bone, and the base of the second and fifth metatarsal bone.Imaging features depend on the primary involvement of cortical versus trabecular bone. Conventional radiographs may remain normal up to 2 to 3 weeks. For cortical bone, early signs of BSIs are a periosteal reaction or the "gray cortex sign," followed by cortical thickening and fracture line depiction. In trabecular bone, a sclerotic dense line may be seen. Magnetic resonance imaging enables early detection of BSIs and can differentiate between a stress reaction and a fracture. We review typical anamnestic/clinical findings, epidemiology and risk factors, imaging characteristics, and findings at typical locations of BSIs at the foot and ankle that may help guide treatment strategy and patient recovery.

Lower-extremity fatigue fracture detection and grading based on deep learning models of radiographs

OBJECTIVES

To identify the feasibility of deep learning-based diagnostic models for detecting and assessing lower-extremity fatigue fracture severity on plain radiographs.

METHODS

This retrospective study enrolled 1151 X-ray images (tibiofibula/foot: 682/469) of fatigue fractures and 2842 X-ray images (tibiofibula/foot: 2000/842) without abnormal presentations from two clinical centers. After labeling the lesions, images in a center (tibiofibula/foot: 2539/1180) were allocated at 7:1:2 for model construction, and the remaining images from another center (tibiofibula/foot: 143/131) for external validation. A ResNet-50 and a triplet branch network were adopted to construct diagnostic models for detecting and grading. The performances of detection models were evaluated with sensitivity, specificity, and area under the receiver operating characteristic curve (AUC), while grading models were evaluated with accuracy by confusion matrix. Visual estimations by radiologists were performed for comparisons with models.

RESULTS

For the detection model on tibiofibula, a sensitivity of 95.4%/85.5%, a specificity of 80.1%/77.0%, and an AUC of 0.965/0.877 were achieved in the internal testing/external validation set. The detection model on foot reached a sensitivity of 96.4%/90.8%, a specificity of 76.0%/66.7%, and an AUC of 0.947/0.911. The detection models showed superior performance to the junior radiologist, comparable to the intermediate or senior radiologist. The overall accuracy of the diagnostic model was 78.5%/62.9% for tibiofibula and 74.7%/61.1% for foot in the internal testing/external validation set.

CONCLUSIONS

The deep learning-based models could be applied to the radiological diagnosis of plain radiographs for assisting in the detection and grading of fatigue fractures on tibiofibula and foot.

KEY POINTS

• Fatigue fractures on radiographs are relatively difficult to detect, and apt to be misdiagnosed. • Detection and grading models based on deep learning were constructed on a large cohort of radiographs with lower-extremity fatigue fractures. • The detection model with high sensitivity would help to reduce the misdiagnosis of lower-extremity fatigue fractures.

Bone stress injuries

Bone stress injuries, including stress fractures, are overuse injuries that lead to substantial morbidity in active individuals. These injuries occur when excessive repetitive loads are introduced to a generally normal skeleton. Although the precise mechanisms for bone stress injuries are not completely understood, the prevailing theory is that an imbalance in bone metabolism favours microdamage accumulation over its removal and replacement with new bone via targeted remodelling. Diagnosis is achieved by a combination of patient history and physical examination, with imaging used for confirmation. Management of bone stress injuries is guided by their location and consequent risk of healing complications. Bone stress injuries at low-risk sites typically heal with activity modification followed by progressive loading and return to activity. Additional treatment approaches include non-weight-bearing immobilization, medications or surgery, but these approaches are usually limited to managing bone stress injuries that occur at high-risk sites. A comprehensive strategy that integrates anatomical, biomechanical and biological risk factors has the potential to improve the understanding of these injuries and aid in their prevention and management.

Does Magnetic Resonance Imaging Grading Correlate With Return to Sports After Bone Stress Injuries? A Systematic Review and Meta-analysis

BACKGROUND

While some studies have failed to reveal any significant relationship between magnetic resonance imaging (MRI) grading and return to sports after bone stress injuries, others have reported either a linear or nonlinear relationship.

PURPOSE

To evaluate the prognostic value of MRI grading for time to return to sports and rate of return to sports after bone stress injuries.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

A systematic search was performed in PubMed, Web of Science, SPORTDiscus, and Google Scholar. Studies reporting return to sports data after bone stress injuries using MRI grading systems were included in this review. The risk of bias was evaluated using the Quality in Prognosis Studies tool. Meta-analyses were performed to summarize the mean time to return to sports. The Pearson correlation was used to determine the relationship between time to return to sports and MRI grade. A meta-analysis of proportions was conducted to determine the percentage of athletes who successfully returned to sports.

RESULTS

A total of 16 studies with 560 bone stress injuries met inclusion criteria. Higher MRI-based grading was associated with an increased time to return to sports (P < .00001). Pooled data revealed that higher MRI-based grading correlated with a longer time to return to sports (r = 0.554; P = .001). Combining all anatomic locations, the mean time to return to sports was 41.7 days (95% CI, 30.6-52.9), 70.1 days (95% CI, 46.9-93.3), 84.3 days (95% CI, 59.6-109.1), and 98.5 days (95% CI, 85.5-112.6) for grade 1, 2, 3, and 4 injuries, respectively. Trabecular-rich sites of injury (eg, pelvis, femoral neck, and calcaneus) took longer to heal than cortical-rich sites of injury (eg, tibia, metatarsal, and other long-bone sites of injury). Overall, more than 90% of all athletes successfully returned to sports.

CONCLUSION

The findings from this systematic review indicate that MRI grading may offer a prognostic value for time to return to sports after the nonsurgical treatment of bone stress injuries. Both MRI grade and location of injury suggest that individually adapted rehabilitation regimens and therapeutic decisions are required to optimize healing and a safe return to sports.

[Stress fractures of the lower limbs]

Stress reactions and fractures represent an important differential diagnostic entity, especially in patients active in sports. The lower extremities have predilection sites for stress fractures, which require special treatment in the context of the underlying risk factors. Clinically, patients usually complain of stress-dependent pain in the affected region and sport activities are mostly limited or even impossible. The detection of acute stress fractures is usually missed by conventional X‑ray within the first 4-6 weeks. The gold standard diagnostic tool is magnetic resonance imaging (MRI). Depending on the location, a distinction must be made between low-risk and high-risk stress fractures. Low-risk fractures show a high healing rate after conservative treatment including load and stress reduction as well as avoiding risk factors. High-risk fractures can take a complicated course under conservative treatment measures and in some cases, surgical intervention is required.

Editorial Commentary: An Optimal Classification System to Guide Prognosis and Treatment in Greater Trochanteric Pain Syndrome: Now We're Speaking the Same Language

The optimal classification system in arthroscopic and related surgery research and clinical practice should be clinically relevant, descriptive, reproducible, simple, inexpensive, safe, and widely applicable. For the hip, classification systems that characterize intra-articular disorders like femoroacetabular impingement (FAI) syndrome, dysplasia, labral tears, and articular cartilage disease predominate the literature. Recently, awareness of peritrochanteric and other extra-articular disorders has increasingly led to greater recognition, diagnosis, and treatment of what has been historically known as "just bursitis". These disorders are far more complex and include greater trochanteric pain syndrome, the spectrum of gluteal tendon pathology, greater trochanteric bursitis, snapping iliotibial band (external coxa saltans), and greater trochanteric-ischial impingement. The utility of an intraoperative greater trochanteric pain syndrome classification system has now been proven using prospectively collected data, assimilating a decade-long eligibility period following open or endoscopic treatment of peritrochanteric disorders with a minimum two-year follow-up using validated patient-reported outcome scores. This classification guides prognosis and treatment, exactly as an optimal orthopedic classification system should do.

Risk Factors, Diagnosis and Management of Bone Stress Injuries in Adolescent Athletes: A Narrative Review

Physical activity is known to be beneficial for bone; however, some athletes who train intensely are at risk of bone stress injury (BSI). Incidence in adolescent athlete populations is between 3.9 and 19% with recurrence rates as high as 21%. Participation in physical training can be highly skeletally demanding, particularly during periods of rapid growth in adolescence, and when competition and training demands are heaviest. Sports involving running and jumping are associated with a higher incidence of BSI and some athletes appear to be more susceptible than others. Maintaining a very lean physique in aesthetic sports (gymnastics, figure skating and ballet) or a prolonged negative energy balance in extreme endurance events (long distance running and triathlon) may compound the risk of BSI with repetitive mechanical loading of bone, due to the additional negative effects of hormonal disturbances. The following review presents a summary of the epidemiology of BSI in the adolescent athlete, risk factors for BSI (physical and behavioural characteristics, energy balance and hormone disruption, growth velocity, sport-specific risk, training load, etc.), prevention and management strategies.

High Cortico-Trabecular Transitional Zone Porosity and Reduced Trabecular Density in Men and Women with Stress Fractures

To determine whether stress fractures are associated with bone microstructural deterioration we quantified distal radial and the unfractured distal tibia using high resolution peripheral quantitative computed tomography in 26 cases with lower limb stress fractures (15 males, 11 females; mean age 37.1 ± 3.1 years) and 62 age-matched healthy controls (24 males, 38 females; mean age 35.0 ± 1.6 years). Relative to controls, in men, at the distal radius, cases had smaller cortical cross sectional area (CSA) (p = 0.012), higher porosity of the outer transitional zone (OTZ) (p = 0.006), inner transitional zone (ITZ) (p = 0.043) and the compact-appearing cortex (CC) (p = 0.023) while trabecular vBMD was lower (p = 0.002). At the distal tibia, cases also had a smaller cortical CSA (p = 0.008). Cortical porosity was not higher, but trabecular vBMD was lower (p = 0.001). Relative to controls, in women, cases had higher distal radial porosity of the OTZ (p = 0.028), ITZ (p = 0.030) not CC (p = 0.054). Trabecular vBMD was lower (p = 0.041). Distal tibial porosity was higher in the OTZ (p = 0.035), ITZ (p = 0.009), not CC. Stress fractures are associated with compromised cortical and trabecular microstructure.

Stress fractures in uncommon location: Six case reports and review of the literature

BACKGROUND

Individuals' interest in sports activities has been increasing, contributing to more stress fracture occurrences in uncommon locations on the skeleton. In this study, several cases of stress fractures in atypical locations are presented, and the possibility of combining diagnostic methods to make accurate and quick diagnoses is explored. Additionally, different causes of stress fractures, as well as various modalities of treatment, are highlighted. Other potential factors of stress fractures were identified by a literature review.

CASE SUMMARY

Six cases of stress fractures in the calcaneus, intermediate cuneiform bone, sacrum, tibia (bilateral), navicular bone and femoral neck are presented, with different types of diagnostic imaging and treatments. All of the cases were associated with an aspect of mobility because all of the patients were physically active in various sport disciplines.

CONCLUSION

The type of therapeutic procedure selected should depend on the specific clinical case, i.e., the patient's condition and level of physical activity.

Evaluating an Algorithm and Clinical Prediction Rule for Diagnosis of Bone Stress Injuries

BACKGROUND

A novel algorithm and clinical prediction rule (CPR), with 18 variables, was created in 2014. The CPR generated a bone stress injury (BSI) score, which was used to determine the necessity of imaging in suspected BSI. To date, there are no validated algorithms for imaging selection in patients with suspected BSI.

HYPOTHESIS

A simplified CPR will assist clinicians with diagnosis and decision making in patients with suspected BSI.

STUDY DESIGN

Prospective cohort study.

LEVEL OF EVIDENCE

Level 3.

METHODS

A total of 778 military trainees with lower extremity pain were enrolled. All trainees were evaluated for 18 clinical variables suggesting BSI. Participants were monitored via electronic medical record review. Then, a prediction model was developed using logistic regression to identify clinical variables with the greatest predictive value and assigned appropriate weight. Test characteristics for various BSI score thresholds were calculated.

RESULTS

Of the enrolled trainees, 204 had imaging-confirmed BSI in or distal to the femoral condyles. The optimized CPR selected 4 clinical variables (weighted score): bony tenderness (3), prior history of BSI (2), pes cavus (2), and increased walking/running volume (1). The optimized CPR with a score ≥3 yielded 97.5% sensitivity, 54.2% specificity, and 98.2% negative predictive value. An isolated measure, bony tenderness, demonstrated similar statistical performance.

CONCLUSION

The optimized CPR, which uses bony tenderness, prior history of BSI, pes cavus, and increased walking/running volume, is valid for detecting BSI in or distal to the femoral condyles. However, bony tenderness alone provides a simpler criterion with an equally strong negative predictive value for BSI decision making.

CLINICAL RELEVANCE

For suspected BSI in or distal to the femoral condyles, imaging can be deferred when there is no bony tenderness. When bony tenderness is present in the setting of 1 or more proven risk factors and no clinical evidence of high-risk bone involvement, presumptive treatment for BSI and serial radiographs may be appropriate.

Part II: presentation, diagnosis, classification, treatment, and prevention of stress fractures in female athletes

Objectives: Stress fractures (SFx) occur as the result of repetitive loads over short periods of time, which leads to micro-damage of the bone through cortical resorption, ultimately leading to fracture. They are a common injury in female athletes and often cause significant morbidity. The goal of this study is to review the presentation, diagnosis, classification, treatment, and prevention of SFx in female athletes.Results: A thorough history, physical exam, and appropriate imaging can facilitate early diagnosis of stress fracture (SFx) and faster resolution of symptoms with more conservative management. The female athlete triad is an especially important factor that contributes to the increased risk of SFx in females. The continuum of stress injuries ranges from mild microfailure to complete fracture, which has resulted in the development of newer grading schemas through MRI and radiographic findings. Stress fractures are also classified as low- or high-risk according to anatomic location, as blood supply and applied forces at different locations affect the likelihood of fracture propagation, displacement, delayed union, or non-union.Conclusions: The ability to screen for at-risk athletes is paramount in preventing SFx. Recognition and prompt treatment of the female athlete triad requires a multidisciplinary approach in order to restore energy balance, correct menstrual irregularities, and improve bone health. This review provides a basis for understanding how to identify and treat stress fractures, which may allow treating physicians to diagnose this condition earlier and minimize any associated morbidity.

Emerging Options for Biologic Enhancement of Stress Fracture Healing in Athletes

In an era of continual single-sport specialization and year-round training, overuse injuries, including stress injuries of bone, are increasingly common. These injuries can be season- or even career-ending. For many elite and professional athletes, the traditional treatment strategy of immobilization and extended rest from sports participation is often not practical or acceptable. An understanding of modern strategies for evaluating and treating stress fractures is paramount for maintaining athletic participation and optimal athletic performance. This begins with the ability to categorize and stratify bony stress injuries by both severity and risk of fracture progression. Surgical procedures such as open reduction and internal fixation or intramedullary fixation with possible bone grafting remain the standard of care for chronic or severe stress fractures. However, emerging techniques to augment the biologic environment are a minimally invasive adjunct for stimulating and supporting bone healing in elite-level athletes to optimize bone health, expedite recovery, and decrease the risk of nonunion or catastrophic fracture.

Sacral Stress Fractures: A Rare but Curable Cause of Back Pain in Athletes

BACKGROUND

Stress fractures of the sacrum are an uncommon cause of low back and buttock pain in athletes. They have been described in a few case reports, with the injury occurring most often in female distance runners. Given the rarity of this condition, there is a general lack of awareness of this injury, which may lead to a missed or delayed diagnosis.

STUDY DESIGN

Case series.

LEVEL OF EVIDENCE

Level 5.

METHODS

The 5 cases were identified by performing a medical records search within the practices of the senior authors over a 3-year period from January 2016 to December 2018.

RESULTS

Three of 5 patients (1 male, 2 females) returned to regular activity after diagnosis and treatment. Two (1 male, 1 female) have yet to return to regular activity. Magnetic resonance imaging was the key modality in all diagnoses. All 3 female patients had components of the female athlete triad-menstrual irregularity, disordered eating, and decreased bone mineral density.

CONCLUSION

A high index of suspicion is required to make the correct diagnosis and initiate treatment for this rare condition given its association with low body mass index, vitamin D insufficiency, disordered eating, and malabsorption disorders. Appropriate treatment includes rest from the causative activity, nutritional support, and biomechanical optimization. In severe, chronic, or recurrent cases, referral for nutritional counseling, hormonal replacement therapies, and mental health support may be necessary.

CLINICAL RELEVANCE

Sacral stress fractures, though uncommon, should be included prominently in the differential diagnosis for runners with low back pain, especially if the athlete has a history of prior stress fracture or the female athlete triad.

Expected Time to Return to Athletic Participation After Stress Fracture in Division I Collegiate Athletes

BACKGROUND

Few studies have documented expected time to return to athletic participation after stress fractures in elite athletes.

HYPOTHESIS

Time to return to athletic participation after stress fractures would vary by site and severity of stress fracture.

STUDY DESIGN

Retrospective cohort study.

LEVEL OF EVIDENCE

Level 3.

METHODS

All stress fractures diagnosed in a single Division I collegiate men's and women's track and field/cross-country team were recorded over a 3-year period. Site and severity of injury were graded based on Kaeding-Miller classification system for stress fractures. Time to return to full unrestricted athletic participation was recorded for each athlete and correlated with patient sex and site and severity grade of injury.

RESULTS

Fifty-seven stress fractures were diagnosed in 38 athletes (mean age, 20.48 years; range, 18-23 years). Ten athletes sustained recurrent or multiple stress fractures. Thirty-seven injuries occurred in women and 20 in men. Thirty-three stress fractures occurred in the tibia, 10 occurred in the second through fourth metatarsals, 3 occurred in the fifth metatarsal, 6 in the tarsal bones (2 navicular), 2 in the femur, and 5 in the pelvis. There were 31 grade II stress fractures, 11 grade III stress fractures, and 2 grade V stress fractures (in the same patient). Mean time to return to unrestricted sport participation was 12.9 ± 5.2 weeks (range, 6-27 weeks). No significant differences in time to return were noted based on injury location or whether stress fracture was grade II or III.

CONCLUSION

The expected time to return to full unrestricted athletic participation after diagnosis of a stress fracture is 12 to 13 weeks for all injury sites.

CLINICAL RELEVANCE

Athletes with grade V (nonunion) stress fractures may require more time to return to sport.

Improving Diagnostic Accuracy and Efficiency of Suspected Bone Stress Injuries

CONTEXT

Lower extremity stress fractures among athletes and military recruits cause significant morbidity, fiscal costs, and time lost from sport or training. During fiscal years (FY) 2012 to 2014, 1218 US Air Force trainees at Joint Base San Antonio-Lackland, Texas, were diagnosed with stress fracture(s). Diagnosis relied heavily on bone scans, often very early in clinical course and often in preference to magnetic resonance imaging (MRI), highlighting the need for an evidence-based algorithm for stress injury diagnosis and initial management.

EVIDENCE ACQUISITION

To guide creation of an evidence-based algorithm, a literature review was conducted followed by analysis of local data. Relevant articles published between 1995 and 2015 were identified and reviewed on PubMed using search terms stress fracture, stress injury, stress fracture imaging, and stress fracture treatment. Subsequently, charts were reviewed for all Air Force trainees diagnosed with 1 or more stress injury in their outpatient medical record in FY 2014.

STUDY DESIGN

Clinical review.

LEVEL OF EVIDENCE

Level 4.

RESULTS

In FY 2014, 414 trainees received a bone scan and an eventual diagnosis of stress fracture. Of these scans, 66.4% demonstrated a stress fracture in the symptomatic location only, 21.0% revealed stress fractures in both symptomatic and asymptomatic locations, and 5.8% were negative in the symptomatic location but did reveal stress fracture(s) in asymptomatic locations. Twenty-one percent (18/85) of MRIs performed a mean 6 days (range, 0- 21 days) after a positive bone scan did not demonstrate any stress fracture.

CONCLUSION

Bone stress injuries in military training environments are common, costly, and challenging to diagnose. MRI should be the imaging study of choice, after plain radiography, in those individuals meeting criteria for further workup.

Taking a holistic approach to managing difficult stress fractures

Stress fractures and other bony stress injuries occur along a spectrum of severity which can impact treatment and prognosis. When treating these injuries, it should be borne in mind that no two stress fractures behave exactly alike. Given that they are not a consistent injury, standardized treatment protocols can be challenging to develop. Treatment should be individualized to the patient or athlete, the causative activity, the anatomical site, and the severity of the injury. A holistic approach to the treatment of the most difficult stress fractures should be taken by orthopedists and sports medicine specialists. This approach is necessary to obtain optimal outcomes, minimize loss of fitness and time away from sports participation, and decrease the risk of recurrence.

Cyclical loading causes injury in and around the porcine proximal femoral physeal plate: proposed cause of the development of cam deformity in young athletes

Background

The repetitive load to which the adolescent athlete’s body is exposed during training and competition affects bone growth. In previous studies, abnormalities of the spine and extremities of adolescent athletes have been described on radiographs and this also applies to the hip. The cam deformity of the hip is an extension of the physeal plate and develops during the adolescent athlete’s growth. Studies of the porcine spine have shown that the vertebral endplates, apophyseal rings and intervertebral discs are susceptible to both static and repetitive loads. The proximal physeal plate of the porcine femur is susceptible to static loads, but no studies have been performed on its susceptibility to repetitive loads. The purpose of this study was to investigate the susceptibility of the proximal porcine femur to repetitive loads.

Methods

Descriptive laboratory study. Seven proximal femurs from four young (5 months) pigs were loaded repetitively (50,000 cycles) using a previously developed model. Three were loaded vertically, three antero-superiorly and one was used as a control. All femurs were examined macroscopically, histologically and with MRI after loading.

Results

No macroscopic injuries were detected on any of the femurs after loading. Fluid redistribution was seen in all femurs on MRI compared with the unloaded control. Injuries were seen in all loaded femurs on microscopic examination of histological samples. Injuries, perpendicularly to the physeal plate and fractures adjacent to the plate, were seen in the vertically loaded specimens. In the antero-superiorly loaded specimen, the injury in the growth plate was parallel to the plate.

Conclusion

Repeated loading of the young porcine hip leads to histological injuries in and adjacent to the physeal plate. These injuries are likely to cause growth disturbances in the proximal femur. We propose that such injuries may be induced in adolescent athletes and offer a plausible explanation for the development of the cam deformity.

The pathophysiology, diagnosis, and management of foot stress fractures

INTRODUCTION

There is an increasing prevalence of osteoporosis, and with it a rise in the diagnosis of stress fractures. Postmenopausal women are particularly at risk of stress fractures. This review article describes the pathophysiology of foot stress fractures and the latest diagnostic and treatment strategies for these common injuries.

DISCUSSION

There are numerous risk factors for stress fractures that have been identified in the literature. Reduced bone mineral density is an independent risk factor for delayed union. Prevention of stress fractures with training periodization and nutritional assessment is essential, especially in females. Diagnosis of stress fractures of the foot is based on history and diagnostic imaging, which include radiographs, ultrasound, therapeutic ultrasound, computed tomography, and bone scans; however, magnetic resonance imaging is still the gold standard. Treatment depends on the bone involved and the risk of nonunion, with high-risk fractures requiring immobilization or surgical intervention. Patients presenting with underlying bone mineral deficiency treated without surgery require a longer period of activity modification. Training rehabilitation protocols are described for those with low-risk stress fractures.

RESULTS

A useful algorithm is presented to guide the clinician in the diagnosis and management of such injuries.

Stress fractures of the ribs and upper extremities: causation, evaluation, and management

Stress fractures are common troublesome injuries in athletes and non-athletes. Historically, stress fractures have been thought to predominate in the lower extremities secondary to the repetitive stresses of impact loading. Stress injuries of the ribs and upper extremities are much less common and often unrecognized. Consequently, these injuries are often omitted from the differential diagnosis of rib or upper extremity pain. Given the infrequency of this diagnosis, few case reports or case series have reported on their precipitating activities and common locations. Appropriate evaluation for these injuries requires a thorough history and physical examination. Radiographs may be negative early, requiring bone scintigraphy or MRI to confirm the diagnosis. Nonoperative and operative treatment recommendations are made based on location, injury classification, and causative activity. An understanding of the most common locations of upper extremity stress fractures and their associated causative activities is essential for prompt diagnosis and optimal treatment.