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Bone stress injuries (BSIs) are common running injuries and may occur at a rate of 20% annually. Both biological and biomechanical risk factors contribute to BSI. Evaluation of a runner with suspected BSI includes completing an appropriate history and physical examination. MRI grading classification for BSI has been proposed and may guide return to play. Management includes activity modification, optimizing nutrition, and addressing risk factors, including the female athlete triad. BSI prevention strategies include screening for risk factors during preparticipation physical examinations, optimizing nutrition (including adequate caloric intake, calcium, and vitamin D), and promoting ball sports during childhood and adolescence.
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Bone Stress Injuries in
Runners
Adam S. Tenforde, MD
a
, Emily Kraus, MD
b
, Michael Fredericson, MD
c,
*
INTRODUCTION
Bone stress injuries (BSIs) in runners result from the failure of skeleton to withstand re-
petitive, submaximal forces from running. BSI can range in severity, with early injuries
showing radiographic findings of periosteal edema with varying degrees of marrow
edema and more advanced stress fractures showing evidence of a fracture line. Stress
fractures account for up to 20% of injuries seen in sports medicine clinic.
1
Studies suggest the annual incidence of BSI may be greater than 20% in runners
and that BSI is a common cause of injury in track and field athletes.
2,3
Early identifica-
tion of a BSI is important in management, because delay in diagnosis or continued
running may result in a higher-grade BSI that requires longer healing time.
4,5
This
article discusses the incidence and distribution of BSI in runners. It reviews biological
and biomechanical risk factors for BSI, with a focus on risk factors that can be
Conflicts of interest: The authors have no conflicts of interest to disclose, and no funding was
received in the preparation of this review.
a
Department of Physical Medicine and Rehabilitation, Harvard Medical School, Spaulding
Rehabilitation Hospital, Spaulding National Running Center, 1575 Cambridge St., Cambridge,
MA 02138, USA;
b
Division of Physical Medicine and Rehabilitation, Department of Orthopae-
dic Surgery, Stanford University, 450 Broadway Street, MC 6120, Redwood City, CA 94063, USA;
c
Division of Physical Medicine and Rehabilitation, Department of Orthopaedic Surgery, Stan-
ford University, 450 Broadway Street, Pavilion A, 2nd Floor MC 6120, Redwood City, CA
94063, USA
* Corresponding author.
E-mail address: mfred2@stanford.edu
KEYWORDS
Stress fractures Runners Female athlete triad Track and field Cross-country
KEY POINTS
Bone stress injuries (BSIs) are a common form of injury in runners of both sexes.
Both biological and biomechanical risk factors may contribute to BSI.
History and physical examination are helpful to diagnose BSI, and MRI may be useful for
radiographic confirmation and grading BSI.
Prevention strategies include screening for risk factors during preparticipation evaluation,
promoting optimal nutrition, and encouraging appropriate bone loading activities,
including ball sports.
Phys Med Rehabil Clin N Am 27 (2016) 139–149
http://dx.doi.org/10.1016/j.pmr.2015.08.008 pmr.theclinics.com
1047-9651/16/$ – see front matter Ó2016 Elsevier Inc. All rights reserved.
efficiently evaluated in the clinic setting. It discusses evaluation and management of
BSI by anatomic location and grade of injury by MRI. In addition, it reviews evidence
for prevention of BSI in runners.
SUMMARY/DISCUSSION
Incidence and Distribution
The incidence of BSI varies by age and sex. In a study comparing high school sports,
female and male athletes participating in cross-country had the first and third highest
incidences of injuries at 10.62 and 5.42 per 100,000 athletic exposures, respectively.
6
In a separate investigation, adolescent runners of both sexes sustained stress frac-
tures at a similar rate of approximately 4% to 5% annually.
7
Elite collegiate runners
may sustain BSIs at a rate exceeding 20% per year.
2
Common sites for BSI include
the tibia, fibula, metatarsals, tarsals, calcaneus, and femur.
RISK FACTORS
Risk factors for BSI can be divided into biological and biomechanical risk factors
(Table 1). Genetics are reported to modulate fracture risk.
8
Medications, including ste-
roids, anticonvulsants, antidepressants, and antacids, may impair bone health. Nutri-
tional deficiencies in calcium and vitamin D increase risk for BSI.
9–11
Female athletes
seem to be at greater risk for BSI than male athletes.
12
Sex-specific differences
include the female athlete triad (hereafter referred to as the triad), defined as the inter-
relationship of energy availability, menstrual function, and bone mineral density
(BMD).
13
Each aspect occurs on a continuum of health with the most severe form of
the triad represented by low energy availability with an eating disorder, functional hy-
pothalamic amenorrhea, and osteoporosis.
13
A female runner may have 1 or more
components of the triad, and greater number of triad risk factors has been associated
with increased risk for BSI in female athletes.
14
In both sexes, prior fracture has been found to be a risk factor for development of
BSI in runners.
7,9,15
Lower whole body bone mineral content values increase risk for
BSI in female runners aged 18 to 26 years.
9
In adolescent female runners, the combi-
nation of menstrual irregularities with fracture history was associated with low bone
density.
16
The largest study to date in male runners identified lower BMD as an inde-
pendent risk factor for increased time for healing from a BSI.
4
In addition, athletes with
Table 1
Risk factors for BSI
Biological Factors Biomechanical Factors
Female sex Training patterns, including volume or
changes in intensity
Genetics Bone characteristics (thinner cortex, lower
bone mineral density)
Medications (including anticonvulsants, steroids,
antidepressants, antacids)
Anatomic considerations (leg length
discrepancy, lean mass, foot type, smaller
calf cross-sectional area)
Female athlete triad (low energy availability,
menstrual dysfunction, and low bone mineral
density)
Other dietary contributors (insufficient calcium
and vitamin D)
Tenforde et al
140
trabecular sites of fracture, including the sacrum, pelvis, and femoral neck, had lower
BMDs in the lumbar spine and proximal femur than runners with fractures in cortical
sites. In addition to bone density, bone geometric properties may predispose to
BSIs, including a thinner cortex of tibia in triathletes
17
and smaller tibial cross-
sectional area in runners.
18
Biomechanical factors can also contribute to BSI. Static alignment and anatomic is-
sues may contribute, including leg length discrepancy,
3,19,20
smaller calf girth,
3
and
cavus
19,21
or planus type foot.
22
Dynamic biomechanical loading patterns experi-
enced during running may also contribute to injury. These characteristics have been
evaluated primarily in female patients who sustain BSI in the tibia and include greater
average vertical loading,
23,24
higher peak acceleration,
25
and greater peak free
mass.
26
Higher peak hip adduction, knee internal rotation, knee abduction, tibial inter-
nal rotation, and rear foot eversion may also contribute.
24,27
Running volumes greater
than 32 km (20 miles) per week increase risk for BSI.
7,22
EVALUATION
Clinical Evaluation
Clinicians should complete a full history and physical examination in runners who pre-
sent for evaluation of a BSI. A complete running history should be obtained (including
changes in running volume, shoe type and duration of use, frequency of racing, and
change in foot strike pattern strategy). In female runners, screening for triad risk fac-
tors is important, including dietary restriction behaviors, daily servings of foods rich in
calcium and vitamin D, menstrual dysfunction, history of fractures, and personal/fam-
ily history of low BMD.
28
Medications including hormones (oral contraceptive pills, es-
trogen, progesterone) and historical or current use of medications that influence bone
health, including steroids and antacids, should be recorded.
During physical examination, the characteristics of a BSI include focal bony tender-
ness and pain with direct and/or indirect percussion. Single-leg hop test may be
attempted to elicit pain depending on the clinical context. In more advanced cases,
local swelling or skin color changes may be noted.
Specific forms of BSI may require additional aspects of the physical examination. In
our clinical experience, and based on available research, we recommend clinicians
consider the following for specific examination findings based on location of pain.
Sacral/pelvic location
In addition to focal tenderness, sacroiliac joint provocative maneuvers may elicit pain,
including thigh thrust; pelvic distraction; pelvic compression; and flexion, abduction,
and external rotation of hip (FABER maneuver). Evaluation for a leg length discrepancy
may be valuable to correct for biomechanical risk factors contributing to injury.
20
Femoral neck
Pain may be provoked with hip internal rotation. In addition, evaluate for the presence of
femoral acetabular impingement with flexion adduction and internal rotation (FADIR
maneuver) because this has been associated with femoral neck BSI.
29
Lesser trochanter
The clinical evaluation is similar to evaluation for a femoral neck BSI. This injury is
typically associated with iliopsoas tendinopathy and is a potentially high-risk injury
because it can progress to full fracture.
30
Femoral shaft
Fulcrum test may localize pain at the site of injury.
31
Bone Stress Injuries in Runners 141
Calcaneus
Calcaneal squeeze test may elicit pain and help differentiate from other causes of heel
pain, including retrocalcaneal bursitis.
ANATOMY AND IMAGING
The anatomic locations for BSI can be divided into high-risk, moderate-risk, and low-
risk locations based on time to heal and risk for nonunion (Table 2). Table 2 is based
on a modified version of previously published high-risk
32
and low-risk classifica-
tions,
33
including a moderate-risk category that may be more challenging to address
given biological and biomechanical forces that can contribute to risk for impaired bone
healing.
MRI is commonly used to evaluate BSI because of the value in grading severity of
injury and use of nonionizing radiation. Multiple grading systems have been devel-
oped.
4,5,34
Two MRI imaging grades are shown in Table 3, including the initial pro-
posed criteria by Fredericson and colleagues
5
that have been most recently
updated by Nattiv and colleagues.
4
MANAGEMENT
Activity Modification and Aerobic Activity
After the initial healing phase to achieve pain-free ambulation and no pain with provoc-
ative maneuvers on physical examination, most athletes initiate a nonimpact loading
activity to maintain fitness and strength, including deep water running. Athletes should
be counseled to maintain good caloric intake to meet the metabolic demands of
cross-training and not inadvertently restrict caloric intake, which may risk delayed
healing response. Use of an antigravity treadmill may allow for progressive impact
loading to maintain fitness while allowing healing of lower extremity BSIs.
35
We out-
lined a protocol used at Stanford University for athletes recovering from BSIs using
an antigravity treadmill that can modulate forces encountered in the lower extremities
to allow for progressive weight bearing.
35
Ensure Adequate Intake of Calcium and Vitamin D
All athletes with BSIs should be assessed to ensure adequate calcium and vitamin D
intake, preferably through diet. Target values published by the Institute of Medicine
based on age and sex in 2010 are as follows
36
:
600 IU of vitamin D daily is recommended for ages 9 to 70 years
800 IU of vitamin D daily is recommended for ages 71 years or older
1300 mg of calcium daily for ages 9 to 18 years
Table 2
Anatomical location and risk of BSI
Low Risk
33
Medium Risk High Risk
32
Posteromedial tibia
Fibula/lateral malleolus
Calcaneus
Diaphysis of second to fourth
metatarsals
Pelvis (sacrum and pubic rami)*
Femoral shaft
Proximal tibia
Cuboid
Cuneiform
Femoral neck
Patella
Anterior tibial diaphysis
Medial malleolus
Talus (lateral process)
* The pelvis is a controversial anatomical location for determining risk for bone stress injury, but
recent research by Nattiv and colleagues
4
showed that time to full return to play is longer in trabec-
ular BSIs.
Tenforde et al
142
1000 mg of calcium daily for women aged 19 to 50 years and men aged 19 to 70
years
1200 mg of calcium daily for women aged 51 years and older and for men 71 years
and older
Clinicians who suspect low energy availability should refer the runner for a complete
nutritional assessment with a registered dietitian. This assessment is best accom-
plished with a dietician who has sports nutrition background and takes into account
sports participation demands, caloric intake, and energy availability, in addition to other
important nutrients of bone health. Given the prevalence of vitamin D deficiency, we
recommend screening athletes who sustain a BSI by measuring 25-OH vitamin D level
and providing supplemental vitamin D if needed to ensure that the runner is not vitamin D
deficient. Further studies are needed to assess the relationship with BSIs and vitamin D.
Female Runners: Screening and Management of the Triad
In female runners, screening for the triad is critical for addressing risk factors for BSI
and identifying health risks in this population. The Female Athlete Triad Coalition state-
ment in 2014 outlined a risk factor assessment score that can be used to help in treat-
ment and return-to-play guidelines in female athletes.
28
The key component to
management of the triad is to ensure adequate energy availability, allow for ovulatory
menstrual cycles, and maintain bone mass.
13
In addition to preventing disruptions to
training from management of BSIs, female athletes may be motivated by research that
suggests that performance improves in athletes who maintain ovulatory function with
adequate nutrition.
37
A full description of the evaluation and management of the fe-
male athlete triad is described elsewhere.
38
One important consideration is to ensure
that female runners understand that adequate energy availability (defined as the differ-
ence between energy intake and estimated energy expenditure standardized to fat-
free mass per day
39
) should be maintained both during the healing process and on
return to full running. Inadvertent low energy availability may occur if a female runner
does not consume adequate calories to meet the metabolic demands of aerobic
cross-training activities.
Evaluation of Bone Health in Male Runners
For male runners with diagnosed BSIs in trabecular sites, including the pelvis, sacrum,
and femoral neck, practitioners should consider work-up for impaired bone health,
including dual-energy X-ray absorptiometry (DXA) to measure BMD and initial endocrine
work-up. Athletes with higher-grade BSI assessed by MRI and lower BMD values may
Table 3
MRI grading systems
MRI Grade
MRI Grading Scales for BSIs
Nattiv et al,
4
2013 Fredericson et al,
5
1995
1 Mild marrow or periosteal edema on T2;
T1 normal
Mild to moderate periosteal edema on
T2; normal marrow on T2 and T1
2 Moderate marrow or periosteal edema
plus positive T2
Moderate to severe periosteal edema on
T2; marrow edema on T2 but not T1
3 Severe marrow or periosteal edema on
T2 and T1
Moderate to severe periosteal edema on
T2; marrow edema on T2 and T1
4 Severe marrow or periosteal edema on
T2 and T1 plus fracture line on T2 or T1
Moderate to severe periosteal edema on
T2; marrow edema on T2 and T1;
fracture line present
Bone Stress Injuries in Runners 143
have a longer healing time before return to sports.
4
BMD values from DXA in athletes less
than 50 years of age should be interpreted using age, ethnicity, and male-sex reference
values (Z-scores). The AmericanCollege of Sports Medicine definesZ-score less than 1
as low bone mass in female athletes participating in weight-bearing sports,
13
although
criteria have not been defined for male athletes. The International Society for Clinical
Densitometry defines Z-scores less than 2 as low bone mass for age in both sexes.
40
RECOMMENDATIONS BY ANATOMIC SITE
Some of the most common locations for injury and management recommendations
are discussed here.
HIGH-RISK LOCATIONS
Femoral Neck and Lesser Trochanter
Femoral neck BSI are considered high risk because of complications that may occur
with nonunion, particularly on the tension side of the bone. Tension-side fractures
may be managed with bed rest, as long as widening of the cortical fracture is not
observed on serial imaging.
41
Fractures adjacent to the lesser trochanter may also
progress to femoral neck stress fractures if non–weight-bearing precautions are not
followed during initial management.
30
For compression side fractures and lesser
trochanteric fractures, we recommend use of crutches to maintain non–weight-
bearing status, with clinical evaluation and repeat imaging to ensure bony healing.
Runners can be advanced to cross-training exercises when pain free on examination
and cortical bridging on radiographs. Consultation with an orthopedic surgeon should
be sought early for tension-side injuries or failure to achieve interval bony healing on
repeat radiographs. Complete healing is typically expected by 2 to 3 months.
1
Anterior Tibial Cortex
Radiographs may include presence of the so-called dreaded black line, visualized as
horizontal radiolucency localized to the tension side of the tibia. Clinicians should
obtain repeat radiographs to ensure bony bridging and healing before progressing
to weight-bearing status. Nonsurgical outcomes in management have been described
as unsatisfying
42
; in the setting of nonunion, an intramedullary rod may be necessary.
Medial Malleolus
Fractures involving the medial malleolus are important to identify given that this struc-
ture contributes to the ankle mortise. A published case series of athletes managed sur-
gically who had radiographic evidence of fracture line had good outcomes
43
; however,
we recommend an initial trial of immobilization unless there was significant displace-
ment of the fracture or involvement of the talocrural joint.
Base of Second Metatarsal
Fractures at the base of the second metatarsal are considered high risk, especially if
the fracture extends to the Lisfranc joint (metatarsal-cuneiform joint). A minimum of
4 weeks’ immobilization is recommended
44,45
and repeat radiographs and clinical
examination are advised to ensure that the runner is pain free before advancing weight
bearing. Morton toe (defined as second toe extending past the great toe) may be
observed on examination and be an associated biomechanical risk factor for this injury
because of increased force transmitted through the second ray of the foot. Custom
foot orthosis with metatarsal pad beneath the second metatarsal may address these
biomechanical forces to reduce risk for future injury.
Tenforde et al
144
Fifth Metatarsal Diaphysis Fractures
Also known as Jones fracture, this injury is considered high risk because of relative
avascularity of the bone distal to the tuberosity, which may result in nonunion.
46
A
review of nonoperative versus surgical management described current quality of evi-
dence as low, although the investigators concluded that better results were observed
with surgery.
42
Use of a CAM walker boot may offload this site most effectively to pro-
mote initial healing.
47
Surgical management, including intramedullary screw fixation
and bone grafting, has been shown to result in predictable healing and return to
play by as early as 12 weeks.
48
Tarsal Navicular
Examination findings may include presence of tenderness over the navicular tuberosity or
navicular-cuneiform joint. Maintaining strictnon–weight-bearing status initially to promote
healingmay result in the best clinical outcome.
49
Computed tomography may be a helpful
imaging modality when assessing for healing response in the setting of a chronic injury.
Saxena and colleagues
50
proposed a grading system for navicular BSI, and higher-
grade injuries treated with surgery may have more favorable outcomes, especially if there
is radiographic evidence of avascular necrosis, cystic changes, or sclerosis.
Sesamoids
The sesamoids consist of a fibular and tibial sesamoid bone. Because of the loading
demands, BSI at this location may have delayed healing response. Use of cushioned
orthosis with accommodative insole to offload the sesamoid is helpful to reduce
biomechanical stress and promote healing. Note that bipartite sesamoid with sesa-
moiditis may radiographically appear as a split sesamoid. Plain radiographs of the
contralateral asymptomatic foot can sometimes show this normal anatomic variant.
MODERATE RISK
Sacrum and Pelvis
Most injuries in the sacrum have radiographic evidence of high-grade BSI. Crutches
and other assistive devices to ensure pain-free mobility are important early in the clin-
ical course and can be discontinued with pain-free ambulation. Runners usually return
to full running activity around 12 weeks.
51
Tarsals Cuboid and Cuneiform
Given their location, both cuboid and cuneiform BSIs can be difficult to heal given the
biomechanical forces and loads encountered through the foot. Management includes
immobilization if needed to ensure pain-free ambulation, followed by progression to a
neutral shoe and physical therapy to address strength and other biomechanical defi-
cits that may have contributed to injury.
Femoral Shaft
Injuries without evidence of displacement or cortical break tend to heal and allow
return to running within 8 to 12 weeks.
1
LOW RISK
Tibia
Injuries are typically located at the distal third posterior medial aspect of the tibia. Clin-
ical features suggestive of more severe injuries include focal pain, tenderness elicited
Bone Stress Injuries in Runners 145
with direct or indirect palpation, and associated MRI grading criteria can predict length
of recovery ranging from 3 to 12 weeks.
5
Fibula
Easy to examine given the surface bony anatomy, these injuries tend to heal quickly
and allow prompt return to running when asymptomatic.
1
Calcaneus
Heel pain in an athlete may be a clue to the presence of an injury involving the calca-
neus. The calcaneal squeeze test is helpful for eliciting bony pain. Given that the bone
has significant trabecular content, screening for female athlete triad risk factors is
particularly important. We recommend initial use of a walking boot and possibly use
of crutches to ensure pain-free mobility.
Metatarsals
With exception of the base of the second metatarsal and fractures involving the meta-
physis of the fifth metatarsal, fractures involving the shaft of metatarsals 2 to 4 are
considered low risk and have good healing response. In lower grade BSI (injury
without presence of fracture line), use of a metatarsal pad and firm-sole shoe may
allow the athlete to ambulate without pain.
1
With the presence of a fracture line, repeat
radiographs at 4 weeks are recommended to document evidence of bony bridging
and cortical hypertrophy over the fracture site, along with a pain-free examination
before advancing to cross-training and starting a return-to-running progression.
Most injuries heal within 6 to 8 weeks to allow return to ground running.
PREVENTION
Participation in Ball Sports During Adolescence
We have proposed prehabilitation strategies, including ball sports (basketball
and soccer) and related activities, during adolescence for 2 years to reduce BSI
risk.
52
These findings are based on prior research showing that military recruits and
runners who participated in ball sports during youth have reduced risk for stress
fractures.
7,53,54
Adequate Calcium and Vitamin D Intake
Calcium and vitamin D intake may reduce risk for BSI. We recommend meeting daily
calcium and vitamin D intake levels published by the Institute of Medicine to optimize
bone health.
36
The role of calcium and vitamin D in fracture prevention has previously
been described. Nieves and colleagues
10
showed that female runners consuming
800 mg of calcium daily have 6-fold increased risk for stress fractures compared
with those with intakes of 1500 mg daily. In this investigation, each cup of milk reduced
prospective fractures by 62%, highlighting other aspects of nutrition as contributing to
risk reduction.
10
Lappe and colleagues
55
found a 20% reduction in female navy re-
cruits who were randomly assigned to supplemental calcium 2000 mg and vitamin
D 800 IU daily during 8-week basic training.
Preparticipation Physical Examination Screening
During preparticipation screening, all athletes should be asked about prior fracture
history and screened for triad risk factors. Female runners should be educated on
the importance of normal menstrual periods during training. Work-up for menstrual
dysfunction should be considered early to address this important aspect of female
runner health.
Tenforde et al
146
SUMMARY
BSI is a common form of overuse injury in runners of both sexes. Clinicians should
consider these injuries on the differential diagnosis for musculoskeletal complaints
in runners. Early and effective management of the injury can help facilitate return to
sport, and addressing underlying risk factors may prevent future injury. Early
screening for triad risk factors, optimizing nutrition, and encouraging participation in
higher-impact activities, including ball sports during adolescence, may reduce the
burden of these injuries in runners and promote overall bone health.
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Bone Stress Injuries in Runners 149
... In more severe cases, stress fractures with distinct fracture lines are present. 3 Stress fractures account for more than 10% of all sport-related injuries, and can be as high as 30% in running. It also represent up to 20% of the injuries treated in sports medicine clinics. ...
... 4,5 In runners, BSIs come from the failure of bones to overcome the repetitive, submaximal forces from running. 3 BSI is a very common cause of injury in track and field athletes, with an annual incidence of BSI more than 20% in runners. 6,7 However, there has been no report on the incidence of BSIs or stress fractures among athletes in Korea. ...
... Early diagnosis of BSIs is most important for treatment, because delayed diagnosis and continued running can lead to highergrades of BSI requiring longer healing time. 3,8 The purpose of this review is to broaden the understanding of stress fractures, as well as to assist in the treatment and prevention of stress fractures by providing information about the epidemiology, risk factors, diagnosis and classification of BSI. In addition, we look forward to seeing a lot of interest and follow-up studies in Korea, a barren area of research on stress fractures. ...
Article
Full-text available
A bone stress injury (BSI) means that the bones cannot tolerate repeated mechanical loads, resulting in structural fatigue and local bone pain. A delay in BSI diagnosis can lead to more serious injuries, such as stress fractures that require longer treatment periods. Therefore, early detection of BSI is an essential part of management. Risk factors for BSI development include biological and biomechanical factors. Medical history and physical examination are the basics for a BSI diagnosis, and magnetic resonance imaging is helpful for confirming and grading. In this paper, the authors review the overall content of BSI and stress fractures which are common in runners. Through this review, we hope that interest in stress fractures will be raised in Korea and that active researches will be conducted.
... The development of TFFs in runners is multifactorial [44], and if improper mechanics are a contributor, it makes sense to address these factors to ensure that a return to running does not result in a reoccurrence of the injury [45]. Similarly, it also makes sense to address technique related faults placing uninjured runners at risk as an injury prevention strategy [46]. ...
... While speculative, this could be as a result of the younger girls having a reduced tibia mass, and therefore reduced effective mass [76]. These studies were limited by small samples sizes, and the fact that comparisons were made against 44 the percentage of their individual maximum [120], or comfortable running velocity [84], rather than an absolute velocity. ...
Thesis
Full-text available
Overuse injuries are common in runners, with tibial fatigue fractures (TFF) being particularly severe in nature and challenging to manage. Acceleration of the tibia at foot-ground contact, measured from accelerometers attached over the distal bone, can be used as a surrogate of lower extremity loading in runners. Elevated tibial acceleration (TA) is a risk factor for TFF. The primary question of this thesis is, what is the effectiveness of a real-time haptic feedback gait retraining intervention in reducing TA in runners. A review of the literature describing the measurement of, and outlining the factors that can affect, the measurement of TA was carried out in conjunction with an experimental study to assess the reliability and variability of these measurements. TA was measured from eighty-five uninjured runners to establish a representative database at four different running speeds. Values ranged from 4.5 g to 20.6 g, and a regression analysis revealed that for typical runners, every 0.1 m/s increase in running velocity resulted in a 0.38 g increase in TA. There were considerable individual variations to this trend. These data also served to identify runners who might be classified as high-impact based on their TA magnitude. Together these studies established the parameters of assessment for a subsequent intervention. An in-depth systematic review of augmented feedback to reduce lower extremity loading in runners at risk of tibial fatigue fracture found moderate evidence to support short-term reductions in tibial acceleration using visual feedback modalities. No studies have exclusively used haptics as a feedback modality with runners. There was also moderate evidence to suggest that eight sessions over two weeks was an appropriate stimulus dose, and that feedback withdrawal may be important to reduce the reliance on feedback. A final laboratory-based intervention study sought to investigate the effectiveness of a real-time haptic feedback system on 18 high TA runners. All but one runner reduced their TA immediately post-intervention. At the group level, when running on a treadmill a 50% reduction in TA was observed post-intervention, and 41% after 4-weeks. The reductions in TA were 28% and 17% at these same timepoints when running over ground. 61% of runners who completed the feedback programme and returned for a follow-up assessment were classed as positive responders to the intervention. The dominant strategies used by runners to reduce their TA were to adopt a higher cadence, while reducing their foot impact velocity and leg stiffness during initial stance. There was a high degree of individual variability in the mechanical strategies used, highlighting the need for a personalised, data-driven approach to understanding the response of each runner. The haptic feedback intervention used in this study appears to be as effective, but less invasive and expensive, compared to other more established modalities, such as visual feedback. This new approach to movement retraining has the potential to revolutionise the way runners engage in gait retraining with the next steps taking them out of the laboratory and into a normal training environment.
... Patients with diagnosed pseudofractures had significantly lower levels of vitamin D compared to patients with MTSS and no pseudofractures, posing a risk factor for the development of insufficient mineralization with subsequent osteomalacia [14,21] as well as an increased risk for the development of pseudofractures [7,13,27] and MTSS [24]. Moreover, insufficient vitamin D levels favor the development of stress injuries [29], stress fractures [23], as well as fractures in general [6]. Assessment of BMD revealed no systemic reduction but significantly higher values in patients with pseudofractures compared to those with MTSS without pseudofractures. ...
Article
Full-text available
Purpose: Medial tibial stress syndrome (MTSS) represents a common diagnosis in individuals exposed to repetitive high-stress loads affecting the lower limb, e.g., high-performance athletes. However, the diagnostic approach and therapeutic regimens are not well established. Methods: Nine patients, diagnosed as MTSS, were analyzed by a comprehensive skeletal analysis including laboratory bone turnover parameters, dual-energy X-Ray absorptiometry (DXA), and high-resolution peripheral quantitative computed tomography (HR-pQCT). Results: In 4/9 patients, bilateral pseudofractures were detected in the mid-shaft tibia. These patients had significantly lower levels of 25-hydroxycholecalciferol compared to patients with MTSS but similar levels of bone turnover parameters. Interestingly, the skeletal assessment revealed significantly higher bone mineral density (BMD) Z-scores at the hip (1.3 ± 0.6 vs. - 0.7 ± 0.5, p = 0.013) in patients with pseudofractures and a trend towards higher bone microarchitecture parameters measured by HR-pQCT at the distal tibia. Vitamin D supplementation restored the calcium-homeostasis in all patients. Combined with weight-bearing as tolerated, pseudofractures healed in all patients and return to competition was achieved. Conclusion: In conclusion, deficient vitamin D levels may lead to pseudofractures due to localized deterioration of mineralization, representing a pivotal component of MTSS in athletes with increased repetitive mechanical loading of the lower limbs. Moreover, the manifestation of pseudofractures is not a consequence of an altered BMD nor microarchitecture but appears in patients with exercise-induced BMD increase in combination with reduced 25-OH-D levels. The screening of MTSS patients for pseudofractures is crucial for the initiation of an appropriate treatment such as vitamin D supplementation to prevent a prolonged course of healing or recurrence. Level of evidence: III.
... These excessive impact loads may be injurious to musculoskeletal tissue including bone or cartilage, especially if these forces are not appropriately attenuated (Radin et al., 1973). Impact load variables measured with force plates have been cited as strong predictors of running-related injuries (Khan et al., 2018;Kiernan et al., 2018;Milner et al., 2006;Pohl et al., 2009;Tenforde et al., 2016;Van der Worp et al., 2016). Unlike continuous straight-line running activities, sports such as soccer also involve a variety of dynamic movements that require high-velocity cutting, pivoting, and acceleration-deceleration manoeuvres. ...
Article
There is little information on the reliability of inertial measurement units for capturing impact load metrics during sport-specific movements. The purpose of this study is to determine the reliability of the Blue Trident IMU sensors in measuring impact load, step count and cumulative bone stimulus during a series of soccer-related tasks. Ten healthy recreational soccer players (age: 27.9 ± 2.18; height: 1.77 ± 0.10 m; mass: 79.02 ± 13.07 kg) volunteered for a 3-visit study and performed 4 tasks. Bilateral impact load, total number of steps and cumulative bone stimulus during the tasks were collected. Data were sampled using a dual-g sensor. Intraclass correlation coefficients (ICC3,1) with 95% confidence intervals assessed between-day reliability. Impact load (0.58-0.89) and cumulative bone stimulus (0.90-0.97) had good to excellent reliability across tasks. ICC values for right/left step count were good to excellent during acceleration-deceleration (0.728-0.837), change direction (0.734-0.955) and plant/cut manoeuvres (0.701-0.866) and fair to good during the ball kick (0.588-0.683). This suggests that wearable sensors can reliably measure the cumulative impact load during outdoor functional movements; however, kicking manoeuvres are less reliable. Measuring impact load in the field expands the ability to capture more ecologically valid data.
... BSIs exist along a pathology continuum that can be defined based on findings on magnetic resonance imaging (MRI). The pathology continuum progresses from periosteal edema with varying degrees of bone marrow edema to more advanced injuries showing evidence of a cortical fracture line [3]. ...
Chapter
Full-text available
Bone stress injuries (BSIs) are a common concern in athletes and occur when bone is unable to withstand repetitive, mechanical loading. Athletes who have delayed healing, incomplete healing, nonunion, or repeat BSI may benefit from systemic treatment modalities to optimize BSI recovery and outcomes. There are case studies of select systemic treatment modalities used in high-level athletes with BSI seeking faster return to competition. This chapter uses evidence-based medicine to highlight the impact of teriparatide, extracorporeal shockwave therapy (ESWT), and bone stimulation devices on BSI recovery. Evidence varies for each treatment modality based on the characteristics of the fracture as well as the duration and method of treatment delivery. Practitioners should research the relevant evidence and should consider a cost-benefit analysis of treatment prior to initiating a systemic treatment modality.
... Bone stress injuries are common injuries sustained by athletes (84), and interventions that can mitigate the risk are warranted. There have been no RCTs in athletes that examined the effects of FS on bone metabolism, or bone mineral density. ...
Article
Despite almost 25 years of fish oil supplementation (FS) research in athletes and widespread use by the athletic community, no systematic reviews of FS in athletes have been conducted. The objectives of the systematic review are to: 1) provide a summary of the effect of FS on the athlete’s physiology, health and performance; 2) report on the quality of the evidence; 3) document any side effects as reported in the athlete research; 4) discuss any risks associated with FS use; 5) provide guidance for FS use and highlight gaps for future research. Electronic databases (PubMed, EMBASE, Web of Science, Google Scholar) were searched up until April 2019. Only randomised placebo-controlled trials (RCTs) in athletes, assessing the effect of FS on a health, physiological/biochemical, or performance variable were included. Of the 137 papers identified through searches, 32 met inclusion criteria for final analysis. Athletes varied in classification from recreational to elite, and from Olympic to professional sports. Mean age for participants was 24.9  4.5 years, with 70% of RCTs in males. We report consistent effects for FS on reaction time, mood, cardiovascular dynamics in cyclists, skeletal muscle recovery, the pro-inflammatory cytokine TNF-alpha, and post-exercise nitric oxide responses. No clear effects on endurance performance, lung function, muscle force or training adaptation were evident. Methodological quality, applying the PEDro scale, ranged from 6 to a maximum of 11, with only four RCTs reporting effect sizes. Few negative outcomes were reported. We report various effects for FS on the athlete’s physiology; the most consistent findings were on the central nervous system, cardiovascular system, pro-inflammatory cytokines, and skeletal muscle. We provide recommendations for future research and discuss the potential risks with FS use.
... This is not surprising, as performance for exercises using this energy system include short-bouts of high-intensity exercise and, thus, may benefit from higher levels of muscle mass (32). Athletes involved in sports emphasizing the PCr/AG/ OP energy systems more frequently reported taking supplements to increase athletic endurance and reduce risk of injury/illness, a finding consistent with the endurance nature of these sports and their elevated injury risk (33). Motivations for supplement use, namely the use of supplements to improve health, reduce risk of injury/illness, and improve recovery, also emerged as significant, independent predictors of overall supplement use. ...
Article
Background: Supplements may expose athletes to dangerous ingredients, banned substances, toxins or contaminants; however, few investigations assess use among collegiate athletes in the U.S. Objective: This cross-sectional study evaluated habitual dietary supplement intake, defined use ≥2 days/week over the past year, in NCAA Division I athletes. Methods: Male and female members of a NCAA Division I team, at two universities in southern California completed a 13-item survey. Among 705 eligible participants, 596 submitted surveys (84.5% response rate), 557 surveys included complete data. Chi-square (χ²) analyses evaluated differences among athletes based on sex, weight status, year in college, and sport-type. Independent t-test or ANOVA evaluated mean differences for continuous variables. Results: A total of 45.2% athletes (n = 252) reported taking supplements (≥2 days/week over the past year). Vitamin/minerals (25.5%, n = 142), protein/amino acids (24.6%, n = 137) were used most frequently. Male, vs female athletes, took more supplements overall (1.2 ± 0.1 vs 0.8 ± 0.1, p = 0.004) and indicated higher use of protein/amino acid products (34.2% vs 13.5%, p < 0.005), whereas, females reported higher use of vitamin/minerals (30.5% vs 21.1%, p < 0.05). Higher supplement use was also reported by athletes with BMI ≥ 30.0 kg/m² (vs <30 kg/m², 1.9 ± 0.3 vs 1.0 ± 0.1, p = 0.02), and athletes in ≥ third college year (vs first or second year, 1.2 ± 0.1 vs 0.9 ± 0.1, p = 0.03). Conclusions: Nearly half of NCAA athletes reported habitual supplements use, with significant variation in patterns based on sex, sport-type, year in college, and weight status.
... Lowrisk locations in the foot and ankle include the calcaneus and the second to fifth metatarsals (excluding the base of the second metatarsal and metaphysis of the fifth metatarsal). 26,78 MRI has the best combined sensitivity and specificity for BSI and is the recommended diagnostic imaging test for assessing the full spectrum of BSI. 79 Management of foot and ankle BSIs depends on anatomic location. ...
Chapter
Athletes vary in their susceptibility to stress fractures, and the cause of stress fractures is multifactorial. Risk factors are often categorized as intrinsic or extrinsic. Intrinsic risk factors can be further subcategorized into non-modifiable or modifiable. Non-modifiable risk factors include gender, race, previous history of fracture, genetics, and anatomic alignment. Modifiable risk factors include relative energy deficiency syndrome, calcium and/or vitamin D deficiency, low body weight, poor biomechanics, strength imbalance, and exposure to specific medications, tobacco, and/or alcohol. Extrinsic risk factors for stress fractures are largely modifiable and include sport or activity type, training variables, and improper equipment. Identifying these risk factors, especially those that are modifiable, can help guide care to prevent injuries in athletes who are at higher risk. Prediction algorithms utilizing risk factors have shown promise in helping to identify high-risk athletes.
Chapter
This chapter will review the management of stress fractures, particularly in acute settings. Stress fractures are common overuse injuries and clinicians should expect to manage these injuries both acutely and chronically. Although stress fractures are not typically acute injuries, stress fractures in high-risk locations often require acute and sometimes emergent medical management, especially if these are allowed to progress to complete fractures. This chapter will review the epidemiology, sideline evaluation, and management of stress fractures. Finally, this will briefly review management of associated risk factors for bony stress injuries including the spectrum of relative energy deficiency in sport (RED-S).
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Bone mineral density (BMD) is the most widely used predictor of fracture risk. We performed the largest meta-analysis to date on lumbar spine and femoral neck BMD, including 17 genome-wide association studies and 32,961 individuals of European and east Asian ancestry. We tested the top BMD-associated markers for replication in 50,933 independent subjects and for association with risk of low-trauma fracture in 31,016 individuals with a history of fracture (cases) and 102,444 controls. We identified 56 loci (32 new) associated with BMD at genome-wide significance (P < 5 × 10(-8)). Several of these factors cluster within the RANK-RANKL-OPG, mesenchymal stem cell differentiation, endochondral ossification and Wnt signaling pathways. However, we also discovered loci that were localized to genes not known to have a role in bone biology. Fourteen BMD-associated loci were also associated with fracture risk (P < 5 × 10(-4), Bonferroni corrected), of which six reached P < 5 × 10(-8), including at 18p11.21 (FAM210A), 7q21.3 (SLC25A13), 11q13.2 (LRP5), 4q22.1 (MEPE), 2p16.2 (SPTBN1) and 10q21.1 (DKK1). These findings shed light on the genetic architecture and pathophysiological mechanisms underlying BMD variation and fracture susceptibility.
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Adolescent runners may be at risk for low bone mineral density (BMD) associated with sports participation. Few prior investigations have evaluated bone health in young runners, particularly males. To characterize sex-specific risk factors for low BMD in adolescent runners. Cross-sectional study; Level of evidence, 3. Training characteristics, fracture history, eating behaviors and attitudes, and menstrual history were measured using online questionnaires. A food frequency questionnaire was used to identify dietary patterns and measure calcium intake. Runners (female: n = 94, male: n = 42) completed dual-energy x-ray absorptiometry (DXA) to measure lumbar spine (LS) and total body less head (TBLH) BMD and body composition values, including android-to-gynoid (A:G) fat mass ratio. The BMD was standardized to Z-scores using age, sex, and race/ethnicity reference values. Questionnaire values were combined with DXA values to determine risk factors associated with differences in BMD Z-scores in LS and TBLH and low bone mass (defined as BMD Z-score ≤-1). In multivariable analyses, risk factors for lower LS BMD Z-scores in girls included lower A:G ratio, being shorter, and the combination of (interaction between) current menstrual irregularity and a history of fracture (all P < .01). Later age of menarche, lower A:G ratio, lower lean mass, and drinking less milk were associated with lower TBLH BMD Z-scores (P < .01). In boys, lower body mass index (BMI) Z-scores and the belief that being thinner improves performance were associated with lower LS and TBLH BMD Z-scores (all P < .05); lower A:G ratio was additionally associated with lower TBLH Z-scores (P < .01). Thirteen girls (14%) and 9 boys (21%) had low bone mass. Girls with a BMI ≤17.5 kg/m(2) or both menstrual irregularity and a history of fracture were significantly more likely to have low bone mass. Boys with a BMI ≤17.5 kg/m(2) and belief that thinness improves performance were significantly more likely to have low bone mass. This study identified sex-specific risk factors for impaired bone mass in adolescent runners. These risk factors can be helpful to guide sports medicine professionals in evaluation and management of young runners at risk for impaired bone health. © 2015 The Author(s).
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Prior literature has suggested an association between the radiographic signs of femoroacetabular impingement (FAI) and femoral neck stress fractures (FNSF) or femoral neck stress reactions (FNSR). At the time of the writing of this article, no study has described the association of FAI and FNSF/FNSR along with the need for surgical intervention and outcomes. To determine the prevalence of radiographic features of FAI in patients diagnosed with FNSF. Retrospective case series. Tertiary care, institutional setting PATIENTS: A medical records search program (XXXXXX Translational Research Integrated Database Environment, XXXXXX University, XXXXXX) was used to retrospectively search for patients 18-40 years old with a history of FNSF or femoral neck stress reaction (FNSR). The records were obtained from the following time frame- 7/25/2003 to 9/23/2011. (Assessment of Risk Factors): Plain radiographs and magnetic resonance imaging (MRI) studies were reviewed for features of cam or pincer FAI. Medical records were reviewed to determine if patients required operative intervention. Incidence of abnormal alpha angle, abnormal anterior offset ratio (AOR), abnormal femoral head/neck junction (FHNJ), coxa profunda, positive crossover sign, and abnormal lateral center to edge angle (LCEA). Twenty-one females and three males [mean age of 27 (range 19-39)] were identified with MRI evidence of femoral neck stress injury. Cam morphology was seen in 10 patients (42%). Pincer morphology could only be assessed in 18 patients, with coxa profunda in 14 (78%) and acetabular retroversion in six (14%). Features of combined pincer and cam impingement were observed in four (17%). Seven patients (29%) had operative intervention, with three (12%) requiring internal fixation of their femoral neck fractures, and all had radiographic evidence of fracture union after surgery. Four patients (17%) had persistent symptoms after healing of their femoral neck stress fractures with conservative treatment and eventually required surgery for FAI, three had no pain at final follow-up, one-year post-surgery, and one was lost to follow-up. The results of the current study suggest that patients in the general population with femoral neck stress injuries have a higher incidence of bony abnormalities associated with pincer impingement, including coxa profunda and acetabular retroversion, although it is unclear if pincer FAI is a true risk factor in the development of FNSF. Bony abnormalities associated with pincer type FAI may predispose patients to femoral neck stress injuries. This study demonstrates an association between pincer FAI and FNSF in the general population, with approximately 1/3 eventually requiring operative intervention for either FNSF or FAI. Copyright © 2015 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.
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The Female Athlete Triad is a medical condition often observed in physically active girls and women, and involves three components: (1) low energy availability with or without disordered eating, (2) menstrual dysfunction and (3) low bone mineral density. Female athletes often present with one or more of the three Triad components, and an early intervention is essential to prevent its progression to serious endpoints that include clinical eating disorders, amenorrhoea and osteoporosis. This consensus statement represents a set of recommendations developed following the 1st (San Francisco, California, USA) and 2nd (Indianapolis, Indiana, USA) International Symposia on the Female Athlete Triad. It is intended to provide clinical guidelines for physicians, athletic trainers and other healthcare providers for the screening, diagnosis and treatment of the Female Athlete Triad and to provide clear recommendations for return to play. The 2014 Female Athlete Triad Coalition Consensus Statement on Treatment and Return to Play of the Female Athlete Triad expert panel has proposed a risk stratification point system that takes into account magnitude of risk to assist the physician in decision-making regarding sport participation, clearance and return to play. Guidelines are offered for clearance categories, management by a multidisciplinary team and implementation of treatment contracts. This consensus paper has been endorsed by the Female Athlete Triad Coalition, an International Consortium of leading Triad researchers, physicians and other healthcare professionals, the American College of Sports Medicine and the American Medical Society for Sports Medicine.
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Sports participation has many benefits for the young athlete, including improved bone health. However, a subset of athletes may attain suboptimal bone health and be at increased risk for stress fractures. This risk is greater for female than for male athletes. In healthy children, high-impact physical activity has been shown to improve bone health during growth and development. We offer our perspective on the importance of promoting high-impact, multidirectional loading activities, including ball sports, as a method of enhancing bone quality and fracture prevention based on collective research. Ball sports have been associated with greater bone mineral density and enhanced bone geometric properties compared with participation in repetitive, low-impact sports such as distance running or nonimpact sports such as swimming. Runners and infantry who participated in ball sports during childhood were at decreased risk of future stress fractures. Gender-specific differences, including the coexistence of female athlete triad, may negate the benefits of previous ball sports on fracture prevention. Ball sports involve multidirectional loading with high ground reaction forces that may result in stiffer and more fracture-resistant bones. Encouraging young athletes to participate in ball sports may optimize bone health in the setting of adequate nutrition and in female athletes, eumenorrhea. Future research to determine timing, frequency, and type of loading activity could result in a primary prevention program for stress fracture injuries and improved life-long bone health. Copyright © 2014 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.
Article
Female participation in running is at a historical high. Special consideration should be given to this population, in whom suboptimal nutritional intake, menstrual irregularity, and bone stress injury are common. Immature athletes should garner particular attention. Advances in the understanding of the Triad and Triad-related conditions have largely informed the approach to the health of this population. Clinicians should be well versed in the. identification of Triad-related risk factors. A multidisciplinary team may be necessary for the optimal treatment of at-risk runners. Nonpharmacologic strategies to increase energy availability in athletes should be used as first-line treatment.