The pathophysiology, diagnosis, and management of foot stress fractures

A continuum damage model of fatigue and failure in whole bone

Predicting the fatigue failure of whole bone may provide insight into the etiology of stress fractures and lead to new methods for preventing and rehabilitating these injuries. Although finite element (FE) models of whole bone have been used to predict fatigue failure, they often do not consider the cumulative and nonlinear effect of fatigue damage, which causes stress redistribution over many loading cycles. The purpose of this study was to develop and validate a continuum damage mechanics FE model for the prediction of fatigue damage and failure. Sixteen whole rabbit-tibiae were imaged using computed tomography (CT) and then cyclically loaded in uniaxial compression until failure. CT images were used to generate specimen-specific FE models and a custom program was developed to iteratively simulate cyclic loading and progressive modulus degradation associated with mechanical fatigue. Four tibiae from the experimental tests were used to develop a suitable damage model and define a failure criterion; the remaining twelve tibiae were used to test the validity of the continuum damage mechanics model. Fatigue-life predictions explained 71% of the variation in experimental fatigue-life measurements with a directional bias towards over-predicting fatigue-life in the low-cycle regime. These findings demonstrate the efficacy of using FE modeling with continuum damage mechanics to predict damage evolution and fatigue failure of whole bone. Through further refinement and validation, this model may be used to investigate different mechanical factors that influence the risk of stress fractures in humans.

Stress fractures

Stress fractures (SF) represent 10%-20% of all injuries in sport medicine. An SF occurs when abnormal and repetitive loading is applied on normal bone: The body cannot adapt quickly enough, leading to microdamage and fracture. The etiology is multifactorial with numerous risk factors involved. Diagnosis of SF can be achieved by identifying intrinsic and extrinsic factors, obtaining a good history, performing a physical exam, and ordering laboratory and imaging studies (magnetic resonance imaging is the current gold standard). Relative energy deficiency in sport (RED-S) is a known risk factor. In addition, for women, it is very important know the menstrual status to identify long periods of amenorrhea in the past and the present. Early detection is important to improve the chance of symptom resolution with conservative treatment. Common presentation involves complaints of localized pain, with or without swelling, and tenderness on palpation of bony structures that begins earlier in training and progressively worsens with activity over a 2- to 3-week period. Appropriate classification of SF based on type, location, grading, and low or high risk is critical in guiding treatment strategies and influencing the time to return to sport. Stress injuries at low-risk sites are typically managed conservatively. Studies have suggested that calcium and vitamin D supplementation might be helpful. Moreover, other treatment regimens are not well established. Understanding better the pathophysiology of SFs and the potential utility of current and future bone-active therapeutics may well yield approaches that could treat SFs more effectively.

Comparison of Ultrasonography to MRI in the Diagnosis of Lower Extremity Bone Stress Injuries: A Prospective Cohort Study

OBJECTIVE

To determine the sensitivity and specificity of ultrasound imaging (USI) compared to the reference-standard of MRI in the diagnosis of bone stress injury (BSI).

METHODS

A prospective blinded cohort study was conducted. Thirty seven patients who presented to an academic sports medicine clinic from 2016 to 2020 with suspected lower-extremity BSI on clinical exam underwent both magnetic resonance imaging (MRI) and USI. Participant characteristics were collected including age, gender and sport. Exclusion criteria included contraindication for dedicated MRI, traumatic fracture, or severe tendon or ligamentous injury. The primary outcome measure was BSI diagnosis by USI. An 8-point assessment system was utilized on USI for diagnosis of BSI, and the Fredericson and Nattiv²² criteria were applied to classify MRI findings.

RESULTS

Thirty seven participants who met study criteria were consented to participate. All participants completed baseline measures. Using MRI, there were 30 (81%) athletes with a positive and seven participants with a negative BSI diagnosis. The most common BSIs in the study were in the metatarsal (54%) and tibia (32%). Compared to MRI, USI demonstrated 0.80 sensitivity (95% confidence interval [CI], 0.61-0.92) and 0.71 specificity (95% CI, 0.29-0.96) in detecting BSI, with a positive predictive value of 0.92 (95% CI, 0.75-0.99) and negative predictive value of 0.45 (95% CI, 0.17-0.77).

CONCLUSIONS

USI is a potentially useful point-of-care tool for practicing sports medicine providers to combine with their clinical evaluation in the diagnosis of BSIs. Further research is ongoing to determine the role of USI in follow-up care and return-to-play protocols.

The Relationship Between Stress Fractures and Bone Turnover Markers Is Unclear in Athletic and Military Populations: A Critically Appraised Topic

Clinical Scenario: Having an indication of how bone is remodeling in response to training load could help identify athletes and military personnel at increased stress fracture (SFx) risk. Direct assessment of bone remodeling is impractical. Biochemical markers of bone turnover are used as an indirect measure of bone remodeling and have potential to inform prevention and treatment efforts. To date, the relationship between bone turnover markers and SFxs in athletes or military personnel remains unclear. Clinical Question: Are SFxs related to bone turnover markers in athletes and military personnel? Summary of Key Findings: Seven met eligibility criteria. In five studies, an association between SFxs and bone turnover markers existed. Clinical Bottom Line: The evidence supporting a relationship between SFxs and bone turnover markers in athletes and military personnel is mixed. While five of the seven studies reported some type of relationship, no studies prospectively measured bone turnover markers in a group of athletes or military personnel without an SFx or without SFx history and followed them over time to reassess bone turnover markers upon SFx occurrence. Strength of Clinical Recommendation: In accordance with the Strength of Recommendation Taxonomy, Grade C is the most appropriate strength of recommendation rating.

Training Load Capacity, Cumulative Risk, and Bone Stress Injuries: A Narrative Review of a Holistic Approach

Bone stress injuries (BSIs) are a common orthopedic injury with short-term, and potentially long-term, effects. Training load capacity, influenced by risk factors, plays a critical role in the occurrence of BSIs. Many factors determine how one's body responds to repetitive loads that have the potential to increase the risk of a BSI. As a scientific community, we have identified numerous isolated BSI risk factors. However, we have not adequately analyzed the integrative, holistic, and cumulative nature of the risk factors, which is essential to determine an individual's specific capacity. In this narrative review, we advocate for a personalized approach to monitor training load so that individuals can optimize their health and performance. We define “cumulative risk profile” as a subjective clinical determination of the number of risk factors with thoughtful consideration of their interaction and propose that athletes have their own cumulative risk profile that influences their capacity to withstand specific training loads. In our narrative review, we outline BSI risk factors, discuss the relationship between BSIs and training load, highlight the importance of individualizing training load, and emphasize the use of a holistic assessment as a training load guide.

Vitamin D and Stress Fractures in Sport: Preventive and Therapeutic Measures-A Narrative Review

There are numerous risk factors for stress fractures that have been identified in literature. Among different risk factors, a prolonged lack of vitamin D (25(OH)D) can lead to stress fractures in athletes since 25(OH)D insufficiency is associated with an increased incidence of a fracture. A 25(OH)D value of <75.8 nmol/L is a risk factor for a stress fracture. 25(OH)D deficiency is, however, only one of several potential risk factors. Well-documented risk factors for a stress fracture include female sex, white ethnicity, older age, taller stature, lower aerobic fitness, prior physical inactivity, greater amounts of current physical training, thinner bones, 25(OH)D deficiency, iron deficiency, menstrual disturbances, and inadequate intake of 25(OH)D and/or calcium. Stress fractures are not uncommon in athletes and affect around 20% of all competitors. Most athletes with a stress fracture are under 25 years of age. Stress fractures can affect every sporty person, from weekend athletes to top athletes. Stress fractures are common in certain sports disciplines such as basketball, baseball, athletics, rowing, soccer, aerobics, and classical ballet. The lower extremity is increasingly affected for stress fractures with the locations of the tibia, metatarsalia and pelvis. Regarding prevention and therapy, 25(OH)D seems to play an important role. Athletes should have an evaluation of 25(OH)D -dependent calcium homeostasis based on laboratory tests of 25-OH-D₃, calcium, creatinine, and parathyroid hormone. In case of a deficiency of 25(OH)D, normal blood levels of ≥30 ng/mL may be restored by optimizing the athlete’s lifestyle and, if appropriate, an oral substitution of 25(OH)D. Very recent studies suggested that the prevalence of stress fractures decreased when athletes are supplemented daily with 800 IU 25(OH)D and 2000 mg calcium. Recommendations of daily 25(OH)D intake may go up to 2000 IU of 25(OH)D per day.

Prophylaxis of Pain and Fractures within Feet in the Course of Osteoporosis: The Issue of Diagnosing

Background

Considering the enormous risk of fractures in the course of osteoporosis in the area of the feet, an important aspect of prophylaxis is periodic and, in special cases, ongoing monitoring of defects and deformations as well as pressure distribution. The purpose of this article is to indicate the role of the examination of posture and pressure distribution during standing, postural balance, and gait, in the prevention of fatigue fractures in the course of osteoporosis, based on the literature review and examples of patients.

Methods

The manuscript consists of two parts; it has a review-analytical character. The first part reviews the literature. The data were obtained using the MEDLINE (PubMed), as well as Cochrane and Embase databases. The database review was carried out focusing mainly on English-language publications, while taking into account the topicality of scientific and research works in the area of osteoporosis. The problem of multiaspects in the area of bone density was pointed out. Considering the above, in the second part, the authors analyzed 11 exemplary patients with osteoporosis, referring to the assessment of foot and lower limb defects using traditional posturological methods and including pedobarography to diagnostic procedures that are used in the assessment of pressure distribution, standing and moving, and an attempt to balance.

Results

Analysis of the research and scientific literature proved the lack of unambiguous diagnostic procedures of the locomotor system recommended for the prevention of fatigue fractures in the course of osteoporosis. The main diagnostic recommendations are imaging tests (most often X-ray), which are recommended in the case of specific clinical symptoms. The analysis of exemplary patients with osteoporosis showed numerous disorders in the distribution of pressure in the plantar part of the feet, which are related, among other things, with their individual defects and lower limbs.

Conclusions

Detailed posture diagnostics and gait estimation, along with the analysis of pressure distribution within the feet are a very important aspect of the prevention of structural degradation and fatigue fractures within the feet. An important postulate for further research and scientific work is the elaboration of the procedures that will serve the preventive diagnostics of the locomotor system, aimed at early detection of threats of fatigue fractures.

A comparative overview of metatarsal stress fractures in premenopausal and postmenopausal women: our single-centre experience with eighty-one patients

PURPOSE

To compare the demographic, clinical, and laboratory features of metatarsal bone stress fractures encountered in premenopausal and postmenopausal women.

METHODS

This retrospective study was carried out in the orthopaedics and traumatology department of our tertiary care centre. Data were collected from the hospital records of a total of 81 women (average age 42.65 ± 12.97) allocated in premenopausal (n = 36) and postmenopausal (n = 45) groups. These two groups were compared in terms of age, body mass index, side, and level of the metatarsal stress fracture, serum levels of vitamin D, duration of complaint and treatment, and T-scores of femur and vertebra as measured by dual-energy X-ray absorptiometry.

RESULTS

The average body mass index (BMI) was 27.00 ± 2.49 kg/m² (range 21.8 to 31.2). The right side was involved in 44 cases (54.3%), while the left side was affected in 37 patients. DXA T-scores were significantly high for group 2 for both femur and vertebra (p < 0.001 for both). Two groups did not exhibit any significant differences in terms of BMI, side of the stress fracture, level and location of the fracture, seasonal distribution, smoking habits, comorbidities, serum levels of vitamin D, durations of complaints, and treatment.

CONCLUSION

Our results indicated that there was no difference between 2 groups in terms of serum vitamin D levels; however, postmenopausal women had higher T-scores of femur and vertebra. Identification of patients under higher risk for stress fractures and elucidation of the possible role of menopause necessitate further controlled, randomized trials on larger series.

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.

Part I: epidemiology and risk factors for stress fractures in female athletes

Objectives: Stress fractures (SFx) are a common athletic injury, occurring in up to 40% of athletes at some point in their career. These injuries can cause pain, permanent disability, financial burden, and loss of playing time. This review presents updated epidemiology and comprehensive analysis of risk factors for stress fractures, especially as it pertains to female athletes.Results: Stress fractures (SFx) account for up to 10% of all orthopedic injuries and up to 20% of injuries seen in sports medicine clinics, with an incidence among female athletes as high as 13%. Lower extremity SFx represent 80-95% of SFx, and the increased popularity of endurance running has contributed to the tibia (49% prevalence) replacing the metatarsals (9%) as the most common location for lower extremity SFx. Studies have demonstrated that 50% of peak bone mass is acquired during adolescence, a 'peak time' for eating disorder and female athlete triad development; furthermore, catch-up growth cannot be expected in athletes with diminished bone growth in this critical period. The female athlete triad (low energy availability with or without disordered eating, menstrual dysfunction, and low bone mineral density) are well-known risk factors for SFx; the risk of SFx for female athletes presenting with a single aspect of the triad is 15-20%, and this risk increases to 30-50% for female athletes presenting with multiple aspects of the triad.Conclusion: This review provides a basis for how to identify populations at greatest risk for SFx. Prompt recognition of the intrinsic and extrinsic risk factors for SFx in female athletes is imperative to early diagnosis and to develop targeted strategies to prevent SFx occurrence or recurrence.

Return to sport following stress fractures of the great toe sesamoids: a systematic review

INTRODUCTION

This review aims to provide information on return rates and times to sport following stress fractures of the great toe sesamoids (SFGTSs).

SOURCES OF DATA

A systematic search of CINAHAL, Cochrane, EMBASE, Google Scholar, Medline, PEDro, Scopus, SPORTDiscus and Web of Science was performed using the keywords 'stress', 'fractures', 'great', 'toe', 'sesamoid', 'athletes', 'sports', 'non-operative', 'conservative', 'operative' and 'return to sport'.

AREAS OF AGREEMENT

Fourteen studies were included: three studies reported on the outcome of conservatively-managed SFGTSs; thirteen studies reported on the outcome of surgically-managed SFGTSs. The management principles were to attempt conservative management for 2-6 months using activity modification, analgesia, orthotics and physiotherapy; if symptoms persisted following this, surgical management was to be recommended, either with internal fixation or sesamoidectomy.

AREAS OF CONTROVERSY

The optimal treatment modalities for SFGTSs remain to be defined.

GROWING POINTS

Internal fixation shows the best return to full-level sport rates with low rates of complications.

AREAS TIMELY FOR DEVELOPING RESEARCH

Future prospective studies should aim to establish the optimal treatment modalities for SFGTSs.

Lower limb stress fractures in sport: Optimising their management and outcome

Stress fractures in sport are becoming increasing more common, comprising up to 10% of all of sporting injuries. Around 90% of such injuries are located in the lower limb. This articles aims to define the optimal management of lower limb stress fractures in the athlete, with a view to maximise return rates and minimise return times to sport. Treatment planning of this condition is specific to the location of the injury. However, there remains a clear division of stress fractures by “high” and “low” risk. “Low risk” stress fractures are those with a low probability of fracture propagation, delayed union, or non-union, and so can be managed reliably with rest and exercise limitation. These include stress fractures of the Postero-Medial Tibial Diaphysis, Metatarsal Shafts, Distal Fibula, Medial Femoral Neck, Femoral Shaft and Calcaneus. “High risk” stress fractures, in contrast, have increased rates of fracture propagation, displacement, delayed and non-union, and so require immediate cessation of activity, with orthopaedic referral, to assess the need for surgical intervention. These include stress fractures of the Anterior Tibial Diaphysis, Fifth Metatarsal Base, Medial Malleolus, Lateral Femoral Neck, Tarsal Navicular and Great Toe Sesamoids. In order to establish the optimal methods for managing these injuries, we present and review the current evidence which guides the treatment of stress fractures in athletes. From this, we note an increased role for surgical management of certain high risk stress fractures to improve return times and rates to sport. Following this, key recommendations are provided for the management of the common stress fracture types seen in the athlete. Five case reports are also presented to illustrate the application of sport-focussed lower limb stress fracture treatment in the clinical setting.

Visualization of stress fractures of the foot using PET-MRI: a feasibility study

BACKGROUND

Diagnosis and treatment of stress fractures still remains to be a clinical and radiological challenge. Therapeutic options vary from conservative treatment to surgical treatment without a clear treatment concept. Recently the combination of PET and MRI has been introduced, aiming a superior diagnostic accuracy in clinical practice. Therefore the aim of our study was to analyse whether PET-MRI would be a feasible technique to recognize stress fractures of the foot and to analyse if our conservative treatment plan leads to a good clinical outcome.

METHODS

Therefore, 20 patients with suspected stress fractures of the foot and ankle underwent plain radiography and (18)F-Fluoride PET-MRI. Two blinded readers assessed in consensus both imaging techniques for the presence of stress fracture, stress reaction or osteoarthritis. Patients with stress fractures or stress reactions in the foot and ankle area underwent our conservative treatment plan, with immobilization in a VACO®ped cast for 6 weeks under partial weight bearing on forearm crutches. The benefit of our conservative therapeutic concept was evaluated by the patients on the basis of VAS and FAOS scoring systems before and after treatment.

RESULTS

8 out of 20 patients underwent conservative treatment after diagnosis of either a stress fracture or a stress reaction of the foot and ankle area. PET-MRI identified four stress fractures and seven stress reactions. In all cases, no pathological findings were present on plain X-ray. FAOS and VAS significantly improved according to the patients' records.

CONCLUSIONS

PET-MRI seems to be a useful modality to diagnose stress fractures and stress reactions of the foot and ankle area, especially when conventional modalities, such as plain radiographs fail. Conservative management is a promising therapeutic option for the treatment of stress fractures. To rule out the benefits compared to a surgical treatment plan, further studies are needed.

Superior performance of cone beam tomography in detecting a calcaneus fracture

Cone beam computed tomography is a state-of-the-art imaging tool, initially developed for dental and maxillofacial application. With its high resolution and low radiation dose, cone beam tomography has been expanding its application fields, for example, to diagnosis of traumata and fractures in the head and neck area. In this study, we demonstrate superior and satisfactory performance of cone beam tomography for the imaging of a calcaneus fracture in comparison to conventional X-ray and computed tomography.

Periodization and physical therapy: Bridging the gap between training and rehabilitation

BACKGROUND

Exercise prescription and training progression for competitive athletes has evolved considerably in recent decades, as strength and conditioning coaches increasingly use periodization models to inform the development and implementation of training programs for their athletes. Similarly, exercise prescription and progression is a fundamental skill for sport physical therapists, and is necessary for balancing the physiological stresses of injury with an athlete's capacity for recovery.

OBJECTIVE

This article will provide the sport physical therapist with an overview of periodization models and their application to rehabilitation.

SUMMARY

In recent decades models for exercise prescription and progression also have evolved in theory and scope, contributing to improved rehabilitation for countless athletes, when compared to care offered to athletes of previous generations. Nonetheless, despite such advances, such models typically fail to fully bridge the gap between such rehabilitation schemes and the corresponding training models that coaches use to help athletes peak for competition. Greater knowledge of periodization models can help sport physical therapists in their evaluation, clinical reasoning skills, exercise progression, and goal setting for the sustained return of athletes to high level competition.