Association of Vitamin D With Stress Fractures: A Retrospective Cohort Study

Considerations Regarding Vitamin D in Foot and Ankle Treatment and Surgery

Although the impact that vitamin D has on bone healing is uncertain in foot and ankle (F&A) surgery, there is support for vitamin D supplementation (2000 IU/day) with calcium (1 g/day) to promote bone healing. Although orthopedic F&A surgeons are frequently the first provider to detect the harbingers of osteoporosis by the occurrence of fragility fractures, this should trigger referral to the appropriate specialist for assessment and treatment. There is circumstantial evidence suggesting a role of hypovitaminosis D in bone marrow edema syndrome and possibly osteochondritis dissecans. There should be a low threshold for assessing vitamin D levels in such patients.

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.

Vitamin D Supplementation and Its Impact on Different Types of Bone Fractures

Vitamin D helps to balance the levels of calcium and phosphorus to maintain proper bone structure. It is also involved in essential biological roles and displays a wide spectrum of potential benefits in the human body. Since there are many types of fractures that occur at specific ages and due to different circumstances, the influence of vitamin D on the frequency of a particular fracture may differ. Thus, the authors investigated the possible preventive effect of vitamin D on the risks of vertebral fractures, hip fractures, stress fractures and pediatric fractures. Additional aspects of vitamin D, especially on recuperation after injures and its impact on the severity of particular fractures, were also discussed. It was suggested that vitamin D supplementation may contribute to a reduction in hip fracture risk due to reduced bone turnover, decreased frequency of falls and improved muscle function. Furthermore, vitamin D appears to lower the risk of stress fractures in athletes and military recruits. Due to a nonunified protocol design, presented investigations show inconsistencies between vitamin D supplementation and a decreased risk of vertebral fractures. However, a vitamin D preventive effect on pediatric fractures seems to be implausible.

Proportion of Navy Recruits Diagnosed With Symptomatic Stress Fractures During Training and Monetary Impact of These Injuries

BACKGROUND

Lower extremity stress fractures result in lost time from work and sport and incur costs in the military when they occur in service members. Hypovitaminosis D has been identified as key risk factor in these injuries. An estimated 33% to 90% of collegiate and professional athletes have deficient vitamin D levels. Other branches of the United States military have evaluated the risk factors for stress fractures during basic training, including vitamin D deficiency. To the best of our knowledge, a study evaluating the correlation between these injuries and vitamin D deficiency in US Navy recruits and a cost analysis of these injuries has not been performed. Cutbacks in military medical staffing mean more active-duty personnel are being deferred for care to civilian providers. Consequently, data that previously were only pertinent to military medical providers have now expanded to the nonmilitary medical community.

QUESTIONS/PURPOSES

We therefore asked: (1) What proportion of US Navy recruits experience symptomatic lower extremity stress fractures, and what proportion of those recruits had hypovitaminosis vitamin D on laboratory testing? (2) What are the rehabilitation costs involved in the treatment of lower extremity stress fractures, including the associated costs of lost training time? (3) Is there a cost difference in the treatment of stress fractures between recruits with lower extremity stress fractures who have vitamin D deficiency and those without vitamin D deficiency?

METHODS

We retrospectively evaluated the electronic medical record at Naval Recruit Training Command in Great Lakes, IL, USA, of all active-duty males and females trained from 2009 until 2015. We used ICD-9 and ICD-10 diagnosis codes to identify those diagnosed with symptomatic lower extremity stress fractures. Data collected included geographic region of birth, preexisting vitamin D deficiency, vitamin D level at the time of diagnosis, medical history, BMI, age, sex, self-reported race or ethnicity, hospitalization days, days lost from training, and the number of physical therapy, primary care, and specialty visits. To ascertain the proportion of recruits who developed symptomatic stress fractures, we divided the number of recruits who were diagnosed with a stress fracture by the total number who trained over that span of time, which was 204,774 individuals. During the span of this study, 45% (494 of 1098) of recruits diagnosed with a symptomatic stress fracture were female and 55% (604 of 1098) were male, with a mean ± SD age of 24 ± 4 years. We defined hypovitaminosis D as a vitamin D level lower than 40 ng/mL. Levels less than 40 ng/mL were defined as low normal and levels less than 30 ng/mL as deficient. Vitamin D levels were obtained at the discretion of the individual treating provider without standardization of protocol. Cost was defined as physical therapy visits, primary care visits, orthopaedic visits, diagnostic imaging costs, laboratory costs, hospitalizations, if applicable, and days lost from training. Diagnostic studies and laboratory tests were incorporated as indirect costs into initial and follow-up physical therapy visits. Evaluation and management code fee schedules for initial visits and follow-up visits were used as direct costs. We obtained these data from the Centers for Medicare & Medicaid Services website. Per capita cost was calculated by taking the total cost and dividing it by the study population. Days lost from training is based on a standardized government military salary of recruits to include room and board.

RESULTS

We found that 0.5% (1098 of 204,774) of recruits developed a symptomatic lower extremity stress fracture. Of the recruits who had vitamin D levels drawn at the time of stress fracture, 95% (416 of 437 [95% confidence interval (CI) 94% to 98%]; p > 0.99) had hypovitaminosis D (≤ 40 ng/mL) and 82% (360 of 437 [95% CI 79% to 86%]; p > 0.99) had deficient levels (≤ 30 ng/mL) on laboratory testing, when evaluated. The total treatment cost was USD 9506 per recruit. Days lost in training was a median of 56 days (4 to 108) for a per capita cost of USD 5447 per recruit. Recruits with deficient vitamin D levels (levels ≤ 30 ng/mL) incurred more physical therapy treatment costs than did those with low-normal vitamin D levels (levels 31 to 40 ng/mL) (mean difference USD 965 [95% CI 2 to 1928]; p = 0.049).

CONCLUSION

The cost of lost training and rehabilitation associated with symptomatic lower extremity stress fractures represents a major financial burden. Screening for and treatment of vitamin D deficiencies before recruit training could offer a cost-effective solution to decreasing the stress fracture risk. Recognition and treatment of these deficiencies has a role beyond the military, as hypovitaminosis and stress fractures are common in collegiate or professional athletes.

LEVEL OF EVIDENCE

Level III, prognostic study.

Prevalence of Female and Male Athlete Triad Risk Factors in Ultramarathon Runners

OBJECTIVE

To identify the prevalence of male and female athlete triad risk factors in ultramarathon runners and explore associations between sex hormones and bone mineral density (BMD).

DESIGN

Multiyear cross-sectional study.

SETTING

One hundred-mile ultramarathon.

PARTICIPANTS

Competing runners were recruited in 2018 and 2019.

ASSESSMENT OF RISK FACTORS

Participants completed a survey assessing eating behaviors, menstrual history, and injury history; dual-energy x-ray absorptiometry for BMD; and laboratory evaluation of sex hormones, vitamin D, and ferritin (2019 cohort only).

MAIN OUTCOME MEASURE

A Triad Cumulative Risk Assessment Score was calculated for each participant.

RESULTS

One hundred twenty-three runners participated (83 males and 40 females, mean age 46.2 and 41.8 years, respectively). 44.5% of men and 62.5% of women had elevated risk for disordered eating. 37.5% of women reported a history of bone stress injury (BSI) and 16.7% had BMD Z scores <-1.0. 20.5% of men had a history of BSI and 30.1% had Z-scores <-1.0. Low body mass index (BMI) (<18.5 kg/m 2 ) was seen in 15% of women and no men. The Triad Cumulative Risk Assessment classified 61.1% of women and 29.2% of men as moderate risk and 5.6% of both men and women as high risk.

CONCLUSIONS

Our study is the first to measure BMD in both male and female ultramarathon runners. Our male population had a higher prevalence of low BMD than the general population; females were more likely to report history of BSI. Risk of disordered eating was elevated among our participants but was not associated with either low BMD or low BMI.

Vitamin D supplementation and body composition changes in collegiate basketball players: a 12-week randomized control trial

Background

Vitamin D promotes bone and muscle growth in non-athletes, suggesting supplementation may be ergogenic in athletes. Our primary aim was to determine if modest Vitamin D supplementation augments favorable body composition changes (increased bone and lean mass and decreased fat mass) and performance in collegiate basketball players following 12 weeks of standardized training.

Methods

Members of a men’s and women’s NCAA D1 Basketball team were recruited. Volunteers were randomized to receive either a weekly 4000 IU Vitamin D₃ supplement (D3) or placebo (P) over 12 weeks of standardized pre-season strength training. Pre- and post-measurements included 1) serum 25-hydroxy vitamin D (25(OH)D); 2) body composition variables (total body lean, fat, and bone mass) using dual-energy X-ray absorptiometry (DXA) scans and 3) vertical jump test to assess peak power output. Dietary intake was assessed using Food Frequency questionnaires. Main outcome measures included changes (∆: post-intervention minus pre-intervention) in 25(OH)D, body composition, and performance.

Results

Eighteen of the 23 players completed the trial (8 females/10 males). Eight received the placebo (20 ± 1 years; 3 females) while ten received Vitamin D₃ (20 ± 2 years; 5 females). Weekly Vitamin D₃ supplementation induced non-significant increases (∆) in 25(OH)D (2.6 ± 7.2 vs. −3.5 ± 5.3 ng/mL; p = 0.06), total body bone mineral content (BMC) (73.1 ± 62.5 vs. 84.1 ± 46.5 g; p = 0.68), and total body lean mass (2803.9 ± 1655.4 vs. 4474.5 ± 11,389.8 g; p = 0.03), plus a non-significant change in body fat (−0.5 ± 0.8 vs. −1.1 ± 1.2%; p = 0.19) (Vitamin D₃ vs. placebo supplementation groups, respectively). Pre 25(OH)D correlated with both Δ total fat mass (g) (r = 0.65; p = 0.003) and Δ total body fat% (r = 0.56; p = 0.02). No differences were noted in peak power output ∆ between the D3 vs. P group (−127.4 ± 335.4 vs. 50.9 ± 9 W; NS). Participants in the D3 group ingested significantly fewer total calories (−526.2 ± 583.9 vs. −10.0 ± 400 kcals; p = 0.02) than participants in the P group.

Conclusions

Modest (~517 IU/day) Vitamin D₃ supplementation did not enhance favorable changes in total body composition or performance, over 3 months of training, in collegiate basketball players. Weight training provides a robust training stimulus for bone and lean mass accrual, which likely predominates over isolated supplement use with adequate caloric intakes.

An Association between Bioavailable 25-Hydroxyvitamin D and Bone Mineral Density in a Diverse Cohort of Collegiate Athletes

INTRODUCTION

Although vitamin D is intimately involved in bone metabolism, the relationship between vitamin D status, as measured by serum total 25-hydroxyvitamin D [25(OH)D] concentration, and bone mineral density (BMD) is weak, particularly in non-White populations. Measurement of bioavailable 25(OH)D has been suggested as a better indicator of vitamin D status than total 25(OH)D concentration. To date, the bioavailable 25(OH)D biomarker has been explored minimally in athletic populations. The purpose of this study was to investigate the relationship between total and bioavailable 25(OH)D concentrations and BMD in collegiate athletes.

METHODS

NCAA Division 1 basketball and swimming athletes served as study participants (n = 53; 28 females, 25 males; 28 basketball players, 25 swimmers). All participants completed dual energy x-ray absorptiometry (DXA) scans for analysis of BMD, blood draws for vitamin D measures, and diet/lifestyle questionnaires.

RESULTS

Overall, total 25(OH)D was 80.0 + 13.9 nmol/L and bioavailable 25(OH)D was 6.0 ± 1.9 nmol/L. There was strong disagreement between total 25(OH)D and bioavailable 25(OH)D concentrations (κ = -0.299; r = -0.129) (p = 0.100); 53% of total participants and 77% of Black participants were classified differently (low vs. normal vitamin D status) based on total and bioavailable 25(OH)D criteria. Black participants had significantly lower total 25(OH)D and higher bioavailable 25(OH)D concentrations than White participants (59.5 vs. 102.5 nmol/L and 7.9 vs. 5.4 nmol/L, respectively) (p < 0.001). Total 25(OH)D and total BMD were not correlated, but bioavailable 25(OH)D and total BMD demonstrated a positive correlation (r = 0.618, p < 0.01).

CONCLUSIONS

These results suggest that bioavailable 25(OH)D concentration may be a better clinical measure of vitamin D status than total 25(OH)D in collegiate athletes as related to BMD, particularly in Black athletes. Further research on the utility of the bioavailable 25(OH)D biomarker in athletes is needed.

Paradoxical Relationships between Serum 25(OH)D and Ferritin with Body Composition and Burnout: Variation by Sex and Sports Team

Adequate serum vitamin D and iron levels are thought to influence physical training adaptations and mood positively. The primary purpose of this prospective, observational study was to investigate relationships between serum 25-OH vitamin D/25(OH)D and serum ferritin levels with body composition and athlete burnout symptoms. Seventy-three collegiate athletes (female: n = 49; male: n = 24) from indoor (swimming, basketball) and outdoor (soccer, cross-country) sports were tested pre-season and post-season for serum 25(OH)D and serum ferritin (nutrient biomarkers) via venipuncture; body composition (total lean mass, bone mineral density/BMD, and % body fat) via dual energy X-ray absorptiometry (DXA) scans; and athlete burnout symptoms (post-season) via the athlete burnout questionnaire (ABQ). When male and female cohorts were combined, significant correlations (Pearson’s r) were noted between pre-season serum 25(OH)D versus the change (∆: post-season minus pre-season) in both BMD (r = −0.34; p = 0.0003) and % body fat (r = −0.28; p = 0.015). Serum ferritin ∆ was significantly associated with lean mass ∆ (r = −0.34; p = 0.003). For burnout symptoms, serum 25(OH)D ∆ significantly explained 20.6% of the variance for devaluation of the sport in the male cohort only. Across time, serum 25(OH)D levels decreased while serum ferritin levels increased, non-significantly, in both males and females. Relationships between nutrient biomarkers and body composition were opposite of physiological expectations.

Beneficial effects of vitamin D on anxiety and depression-like behaviors induced by unpredictable chronic mild stress by suppression of brain oxidative stress and neuroinflammation in rats

The objective of this study was to investigate the protective effects of vitamin D (Vit D) on anxiety and depression-like behaviors induced by unpredictable chronic mild stress and brain tissue oxidative damage criteria and neuroinflammation in rats. The rats were treated as follows: (1) control, (2) UCMS, (3-5) Vit D 100, 1000, and 10,000 iu + UCMS. Rats were subjected to UCMS for a total of 4 weeks. During week 4, they received seven training trials. The brains were then collected to examine inflammation and oxidative stress criteria. Pretreatment with Vit D enhanced performances of the rats in the elevated plus maze (EPM) and open field (OF) and forced swimming test (FST). UCMS also increased MDA and interleukin-6 (IL-6) levels while decreased CAT, SOD, and thiol. Vit D reversed the effects of UCMS. The results of the current research revealed that Vit D improved UCMS-induced anxiety and depression via decreasing brain oxidative stress and inhibiting neuroinflammation.

Management of ankle injuries in professional basketball players: Prevalence and rehabilitation

Basketball is a popular internationally played sport. With the physical requirements the game has on athletes, players are at risk of injury. Ankle injuries are the most common injury type suffered by basketball players. In this comprehensive review, we present an analysis and overview of the most common ankle injuries among basketball players, including sprains, fractures, impingement, and Achilles tendon pathology. The review includes treatment modalities for such injuries. More research is warranted regarding prevention strategies.

Acute presentation of a proximal fibular stress fracture after a total knee arthroplasty

A 67-year-old woman underwent a routine and uneventful elective total knee arthroplasty for osteoarthritis at our centre. No intraoperative nor immediate postoperative complications were noted clinically nor radiologically. At 5 weeks postoperative, she began to notice some new discomfort in her upper calf area, with no preceding history of trauma. A Doppler ultrasound scan ruled out a deep vein thrombus. Only on further re-imaging of her knee with X-rays and CT was there shown to be a fibular fracture of the proximal third with evidence of callus formation. The pain arising from her stress fracture delayed her rehabilitation slightly, going on to require a successful manipulation under anaesthetic (0°-95°). She went on to have excellent function in her knee and the pain from the stress fracture had settled by 5 months.

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.

[Musculoskeletal laboratory diagnostics in competitive sport]

Hintergrund

Die labordiagnostische Untersuchung stellt eine wichtige Möglichkeit zur Beurteilung und Optimierung der Leistungs- und Regenerationsfähigkeit professioneller Athleten dar. Ferner ist sie für die Prävention, Diagnostik und Rehabilitation von Verletzungen und Überbelastungen von Bedeutung.

Fragestellung

Ziel dieser Arbeit ist die Darstellung muskuloskelettaler laborchemischer Parameter, die relevante Erkenntnisse für die medizinische Betreuung von Leistungssportlern liefern.

Material und Methoden

Literaturrecherche und narratives Review.

Ergebnisse

Die Bestimmung des Vitamin-D-, Calcium- und Knochenstoffwechsels stellt die laborchemische Basisdiagnostik im Rahmen der Beurteilung des Skelettstatus mit zusätzlichem präventivem Nutzen bezüglich muskuloskelettaler Verletzungen dar. Ferner können muskuläre Serummarker, z. B. Laktatdehydrogenase (LDH), Kreatinkinase (CK), Myoglobin und Aspartat-Aminotransferase (ASAT), helfen, eine metabolische Adaptation an das physische Training festzustellen und Aussagen über die muskuläre Arbeitslast und mögliche Schädigungen zu gewinnen. Die Energieverfügbarkeit kann durch eine entsprechende Bilanzierung sowie die laborchemische Bestimmung der Makro- und Mikronährstoffe eingeschätzt und optimiert werden.

Schlussfolgerungen

Die labordiagnostische Untersuchung besitzt in der Betreuung von Athleten eine sportartenübergreifende klinische Relevanz. Sie dient der Erreichung einer höchstmöglichen Leistungsfähigkeit sowie optimalen Prävention von Knochen- und Muskelverletzungen, wobei sämtliche Mangelzustände (z. B. Vitamin D) ausgeglichen werden sollten. Durch eine Periodisierung der laborchemischen Untersuchungen, mit zumindest zwei Labordiagnostiken im Jahr, und Aufstellung individueller Variabilitäts- und Referenzbereiche kann ferner eine bessere Beurteilbarkeit erreicht werden.

Adolescent Athlete Stress Fractures Associated with Vitamin D Insufficiency: Three Cases with Review of the Literature

CASE

The authors present 3 adolescent athletes who presented with stress fractures in their lower extremities, initially diagnosed as tumors. All 3 patients received an inconclusive magnetic resonance imaging before referral; fractures were confirmed on radiographs and computed tomography. All were found to have vitamin D insufficiency.

CONCLUSIONS

Vitamin D insufficiency is a global epidemic mainly focused on adults and young-adult athletes. These case reports raise concerns about a growing prevalence of vitamin D insufficiency in adolescents, the potential risk of stress fracture, and the need for screening and possible supplementation in adolescent athletes to improve their bone health.

Prevalence of Vitamin D Insufficiency and Deficiency in Young, Female Patients With Lower Extremity Musculoskeletal Complaints

BACKGROUND

Low levels of vitamin D have well-known impacts on bone health, but vitamin D also has a more global role throughout many tissues, including skeletal muscle. The high prevalence of hypovitaminosis D and the vast physiological features of vitamin D have led researchers to examine the influence of vitamin D on physical performance and injury. Because of the critical role of vitamin D in maintaining musculoskeletal health and function, a high rate of hypovitaminosis D among female patients with a variety of musculoskeletal issues could be of high clinical relevance.

HYPOTHESIS

There is a high prevalence of low vitamin D in female patients with both acute and overuse sports-related issues of both soft tissue and bone.

STUDY DESIGN

Prospective cohort study.

LEVEL OF EVIDENCE

Level 3.

METHODS

Female patients, aged 16 to 40 years, presenting with lower extremity injury diagnosed within the past 4 weeks, no use of multivitamin or vitamin D supplement, and no history of malabsorption syndrome met the inclusion criteria. Vitamin D levels were assessed and categorized as normal (≥32 ng/mL) and low, which includes insufficient (20.01-31.9 ng/mL) and deficient (≤20 ng/mL).

RESULTS

Of the 105 patients enrolled, 65.7% had low vitamin D. Within the low vitamin D cohort, 40.6% were deficient and 59.4% were insufficient. Injuries were grouped into overuse or acute with 74 overuse injuries and 31 acute injuries, exhibiting low vitamin D prevalence of 60.8% and 77.4%, respectively. Patients with ligamentous/cartilaginous injuries exhibited the highest percentage of low vitamin D (76.5%), followed by those with patellofemoral-related complaints (71.0%), muscle/tendon injuries (54.6%), and bone stress injuries (45.5%). In univariable analysis, older age, non-White race, less physical activity, less high-intensity interval training days, less endurance training days, and more rest days showed an association with low vitamin D, but none showed an independent association in multivariable analysis.

CONCLUSION

The prevalence of low vitamin D in female patients with various musculoskeletal complaints was high. Clinicians should evaluate for low vitamin D in both acute and overuse injuries.

CLINICAL RELEVANCE

In addition to screening, this study suggests that clinicians should evaluate for low vitamin D levels beyond bone stress injuries in the setting of acute and overuse injuries.

Association of Serum Vitamin D Levels and Stress Fractures in Collegiate Athletes

Background

Low vitamin D levels along with high-intensity athletic training may put an athlete at increased risk for a stress fracture.

Purpose

To assess whether supplementation with vitamin D is associated with a reduced risk of stress fractures in college athletes. We also assessed differences in vitamin D levels among athletes participating in outdoor versus indoor sports.

Study Design

Cohort study; Level of evidence, 2.

Methods

The study participants included 802 National Collegiate Athletic Association Division I intercollegiate athletes (497 men and 305 women) on a sports team for at least 1 semester from 2012 to 2018. All athletes who had a baseline vitamin D level in their medical record were included. Athletes with vitamin D levels <40 ng/mL were given vitamin D supplements. We assessed differences in the rate of stress fracture among those who maintained or improved vitamin D levels to ≥40 ng/mL and those who did not, as well as differences in average baseline vitamin D levels by sport type (indoor vs outdoor).

Results

The rate of stress fracture was 12% higher (95% CI, 6-19; P < .001) for those who remained low in vitamin D compared with those who were low at baseline but improved their vitamin D status to ≥40 ng/mL. The rate of stress fracture was also 12% higher (95% CI, 5-18; P < .001) for those who had low vitamin D levels compared with those who maintained normal levels. The mean baseline vitamin D values were significantly higher for men participating in outdoor sports versus indoor sports. For men, the mean vitamin D level was 5.7 ng/mL higher (95% CI, 0.9-10.5; P = .01) in outdoor athletes. For women, the mean vitamin D level was 3.7 ng/mL higher (95% CI, -0.58 to 8.03; P < .04) for outdoor versus indoor sports.

Conclusion

Study results indicated that correcting low serum vitamin D levels reduces the risk of stress fracture. This study also presented evidence that athletes who participate in indoor sports may be at greater risk for vitamin D deficiency than those who compete in outdoor sports.

Vitamin D for Improved Bone Health and Prevention of Stress Fractures: A Review of the Literature

Vitamin D is a vital nutrient and hormone needed for many essential functions in overall health. There is growing literature examining the role of vitamin D not only in the general population but also in athletes. The most predominantly studied area of vitamin D pertains to bone health. Recently, there has been increased investigation into the relationship of vitamin D and stress fractures, including genetic polymorphisms, levels of 25-hydroxyvitamin D, and bioavailable vitamin D. This review will address the most recent developments of vitamin D research and its important role in bone health in athletes.

Jones Fracture Management in Athletes

Jones fractures in both elite and recreational athletes are best treated with surgical fixation, given superior results as compared to nonoperative management. While screw specifics remain controversial, intramedullary screw fixation is established as the standard surgical technique. Plate fixation also has shown excellent outcomes. Complications of refracture, nonunion, and delayed union require careful evaluation for contributions of early return to play, implant characteristics, and anatomic/metabolic abnormality. Revision fixation with autograft and biologic augmentation is supported in the literature, with ongoing inquiry to optimizing specific implants and adjuvants.

Nutrition and Athlete Bone Health

Athletes should pay more attention to their bone health, whether this relates to their longer-term bone health (e.g. risk of osteopenia and osteoporosis) or their shorter-term risk of bony injuries. Perhaps the easiest way to do this would be to modify their training loads, although this advice rarely seems popular with coaches and athletes for obvious reasons. As such, other possibilities to support the athletes’ bone health need to be explored. Given that bone is a nutritionally modified tissue and diet has a significant influence on bone health across the lifespan, diet and nutritional composition seem like obvious candidates for manipulation. The nutritional requirements to support the skeleton during growth and development and during ageing are unlikely to be notably different between athletes and the general population, although there are some considerations of specific relevance, including energy availability, low carbohydrate availability, protein intake, vitamin D intake and dermal calcium and sodium losses. Energy availability is important for optimising bone health in the athlete, although normative energy balance targets are highly unrealistic for many athletes. The level of energy availability beyond which there is no negative effect for the bone needs to be established. On the balance of the available evidence it would seem unlikely that higher animal protein intakes, in the amounts recommended to athletes, are harmful to bone health, particularly with adequate calcium intake. Dermal calcium losses might be an important consideration for endurance athletes, particularly during long training sessions or events. In these situations, some consideration should be given to pre-exercise calcium feeding. The avoidance of vitamin D deficiency and insufficiency is important for the athlete to protect their bone health. There remains a lack of information relating to the longer-term effects of different dietary and nutritional practices on bone health in athletes, something that needs to be addressed before specific guidance can be provided.

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.

Bone Stress Injuries Are Associated With Differences in Bone Microarchitecture in Male Professional Soldiers

Bone stress injuries are commonly due to repetitive loading, as often described in competitive athletes or military recruits. The underlying pathophysiology of bone stress injuries is multifactorial. The present cross-sectional study investigated (i) cortical and trabecular bone microstructure as well as volumetric bone mineral density in subjects with bone stress injuries at the tibial diaphysis, measured at the distal tibia and the distal radius by means of high-resolution peripheral quantitative computed tomography (CT), (ii) areal bone mineral density using dual-energy X-ray absorptiometry as well as calcaneal dual X-ray absorptiometry and laser, and (iii) the influence on bone turnover markers of formation and resorption at the early phase after injury. A total of 26 Caucasian male professional soldiers with post-training bone stress injury at the tibial diaphysis were included (case group). A total of 50 male, Caucasian professional soldiers from the same military institution served as controls (control group). High-resolution peripheral quantitative CT revealed a higher total area at the radius within the case group. Cortical bone mineral density was reduced at the radius and tibia within the case group. The trabecular number and trabecular thickness were reduced at the tibia in the case group. The trabecular network was more inhomogeneous at the radius and tibia within the case group. Calcaneal dual X-ray absorptiometry and laser was significantly reduced in the case group. This study quantified differences in bone microstructure among otherwise healthy individuals. Differences in bone microarchitecture may impair the biomechanical properties by increasing the susceptibility to sustain bone stress injuries. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2516-2523, 2019.

Vitamin D and foot and ankle trauma: An individual or societal problem

BACKGROUND

Vitamin D deficiency is a worldwide health concern. Hypovitaminosis D may adversely affect recovery from bone injury. The authors aimed to perform an audit of the Vitamin D status of patients in three centres in the United Kingdom presenting with foot and ankle osseous damage.

METHODS

Serum 25-hydroxyvitamin-D (vitamin D) levels were obtained in patients presenting with imaging confirmed foot and ankle osseous trauma. Variables including age, gender, ethnicity, location, season, month, anatomical location and type of bone injury were recorded.

RESULTS

308 patients were included from three different centres. 66.6% were female. The average age was 47.7 (range; 10-85). The mean hydroxyvitamin-D levels were 52.0 nmol/L (SD 28.5). 18.8% were grossly deficient, 23.7% deficient, 34.7% insufficient and 22.7% within normal range. 351 separate bone injuries were identified of which 104 were categorised as stress reactions, 134 as stress fractures, 105 as fractures and 8 non-unions. Age, gender, anatomical location and fracture type did not statistically affect vitamin D levels. Ethnicity did affect Vitamin D levels: non-Caucasians mean levels were 32.4 nmols/L compared to Caucasian levels of 53.2 nmol/L (p=0.0026).

CONCLUSION

Only 18.8% of our trauma patients had a normal Vitamin D level and 22.7% were grossly deficient. Patient age, gender, anatomical location and injury type did not statistically affect vitamin D levels. No difference between trauma and elective patients were found. Hypovitaminosis D is a problem of society in general rather than specific to certain foot and ankle injury patterns or particular patient groups sustaining trauma.

LEVEL OF EVIDENCE

2b.

Current concepts in vitamin D and orthopaedic surgery

INTRODUCTION

Vitamin D plays an important role in the musculoskeletal system of the human body. Here, we review the most current literature on vitamin D as it relates to orthopaedic surgery and the musculoskeletal system, focusing largely on non-fracture applications.

MATERIALS AND METHODS

A literature review was performed on the basic science of vitamin D metabolism, epidemiology of vitamin D levels, role of vitamin D within the musculoskeletal system, and the correlation of vitamin D with injuries and orthopaedic surgical outcomes.

RESULTS

The existing literature suggests vitamin D plays multiple roles in the musculoskeletal system. Recent research has shed light on the importance of vitamin D in the setting of soft tissue healing and recovery in addition to affecting postoperative outcomes after common orthopaedic procedures.

CONCLUSIONS

Given the widespread prevalence of vitamin D deficiency, orthopaedic surgeons should be aware of the current evidence regarding clinical implications in patients with musculoskeletal complaints.

Nutrition for the Prevention and Treatment of Injuries in Track and Field Athletes

Injuries are an inevitable consequence of athletic performance with most athletes sustaining one or more during their athletic careers. As many as one in 12 athletes incur an injury during international competitions, many of which result in time lost from training and competition. Injuries to skeletal muscle account for over 40% of all injuries, with the lower leg being the predominant site of injury. Other common injuries include fractures, especially stress fractures in athletes with low energy availability, and injuries to tendons and ligaments, especially those involved in high-impact sports, such as jumping. Given the high prevalence of injury, it is not surprising that there has been a great deal of interest in factors that may reduce the risk of injury, or decrease the recovery time if an injury should occur: One of the main variables explored is nutrition. This review investigates the evidence around various nutrition strategies, including macro- and micronutrients, as well as total energy intake, to reduce the risk of injury and improve recovery time, focusing upon injuries to skeletal muscle, bone, tendons, and ligaments.

Treatment of Medial Tibial Stress Syndrome With Radial Soundwave Therapy in Elite Athletes: Current Evidence, Report on Two Cases, and Proposed Treatment Regimen

Two case reports of high-level athletes with medial tibial stress syndrome (MTSS), 1 an Olympian with an actual stress fracture, are presented. Successful treatment included radial soundwave therapy, pneumatic leg braces, relative rest using an antigravity treadmill, and temporary foot orthoses. Radial soundwave therapy has a high level of evidence for treatment of MTSS. We also present recent evidence of the value of vitamin D assessment. Both patients had a successful outcome with minimal downtime. Finally, a suggested treatment regimen for MTSS is presented.

Effects of Vitamin D on Skeletal Muscle and Athletic Performance

Vitamin D is known to be important for calcium homeostasis and bone metabolism. It also has important direct effects on skeletal muscle. Unlike authentic vitamins, which cannot be synthesized in the body, vitamin D is produced in the skin using sunlight. Through its nuclear receptor (ie, vitamin D receptor) located throughout the body, including skeletal muscle, vitamin D initiates genomic and nongenomic pathways regulating multiple actions, including myocyte proliferation and growth. In some studies, vitamin D supplementation has been shown to increase muscle strength, particularly in people who are vitamin D deficient. Higher serum levels of vitamin D are associated with reduced injury rates and improved sports performance. In a subset of the population, vitamin D appears to play a role in muscle strength, injury prevention, and sports performance.

Sun exposure in pigs increases the vitamin D nutritional quality of pork

There is a high prevalence of vitamin D insufficiency and deficiency worldwide likely because of both limited sun-exposure and inadequate dietary intake. Meat, including pork, is not typically considered a dietary source of vitamin D, possibly because of management practices that raise pigs in confinement. This experiment determined the vitamin D content of loin and subcutaneous adipose tissue in sun-exposed finisher pigs. Two separate groups of pigs were used. The first group (28 white Landrace-Duroc) was assigned at random to either sunlight exposure (SUN) in spring and summer or confinement per standard practice (Control). The second (24 Yorkshire-Duroc-Landrace) underwent the same exposure protocol but was exposed in summer and fall or assigned to control (Control). A subsample of five SUN and four Control pigs, matched for weight and body condition score, was selected for slaughter from each group. Pigs (n = 10 SUN, n = 8 Control) had blood drawn for analysis of 25(OH)D₃ concentration before/after sun exposure or control, and tissue samples were taken at slaughter for analysis of tissue vitamin D3 and 25(OH)D₃ concentration. Three random samples from a single loin chop and surrounding adipose were collected and analyzed. Serum concentrations of 25(OH)D₃ did not differ (P≥0.376) between treatments prior to sun exposure in either group, but was increased (time*treatment interaction, P<0.001) with SUN exposure. Total vitamin D content (D3 plus 25(OH)D₃) of loin tissue was increased (P < 0.001) with sun exposure and averaged 0.997±0.094 μg/100g and 0.348±0.027 μg/100g for sun and control pigs, respectively. While exposure to sunlight increased (P = 0.003) tissue content of 25(OH) D in subcutaneous adipose tissue, vitamin D₃ content was similar between treatments (P = 0.56). Sunlight exposure in pigs increased the vitamin D content of loin, and may provide an additional source of dietary vitamin D.