Stress fractures

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

History should quantify load rather than merely asking about exercise. Record recent changes in distance, speed, hills, surface, footwear, pack weight, competition, work and recovery days. Map pain onset, whether it now occurs earlier during activity, persists at rest or caused an acute crack. Ask about previous stress or fragility fractures, osteoporosis, glucocorticoids, anticonvulsants, malabsorption, renal or thyroid disease, pregnancy and lactation, smoking and alcohol. In older adults, normal household activity can be sufficient for an insufficiency fracture.

Assess low energy availability sensitively in every sex and body size. Ask about intentional or unintentional weight change, dietary restriction, food insecurity, training without fuelling, menstrual cycle, libido, morning erections, fertility, fatigue, mood, recurrent illness and declining performance. A normal body mass index does not exclude relative energy deficiency in sport. Avoid blame and involve sports medicine, dietetics, endocrinology and mental-health or eating-disorder services according to risk; severe physiological compromise requires urgent medical care.

Local examination seeks a reproducible bony focus and high-risk site. Observe gait and alignment, palpate along the full bone, compare sides and assess adjacent joints, muscle strength and tendon function. Hop testing may reproduce low-risk tibial or metatarsal pain but should not be performed when femoral-neck injury, high-risk anatomy or completed fracture is possible. Femoral-neck stress injury may present only as deep groin or thigh pain, pain at end-range rotation and an antalgic gait without visible swelling.

Initial radiographs establish alignment, reveal a fracture line, cortical thickening, periosteal response, sclerosis or an alternative destructive lesion. Sensitivity is limited early because bone reaction takes time. When clinical suspicion remains, MRI is preferred: lower grades show periosteal and marrow oedema, while a fracture line indicates more advanced injury. MRI also distinguishes many soft-tissue differentials. CT gives superior cortical detail for navicular, anterior tibial and fifth-metatarsal injury, union or surgery. Bone scintigraphy is an alternative when MRI is unavailable but is less specific and exposes the patient to radiation.

Anatomical risk changes urgency. Compression-side inferior femoral-neck injury may heal with strict protection if incomplete and stable, while a tension-side superior lesion is prone to displacement and commonly needs fixation assessment. Anterior tibial cortical defects, navicular fractures, talar lesions and zone-two or zone-three fifth-metatarsal injuries have adverse mechanical or vascular environments. Lower-risk posteromedial tibial, fibular and central metatarsal-shaft injuries usually respond to activity modification when diagnosis and adherence are secure.

Treatment removes the causative load while preserving health. Stop running, jumping and painful walking; use a boot and crutches or strict non-weight bearing according to site and grade. An acute complete or displaced fracture follows trauma fixation principles. High-risk injuries need early orthopaedic or specialist sports review, with prophylactic fixation considered from site, fracture line, symptoms, athlete demands and progression. Low-risk injury can progress through pain-free daily activity, cross-training, strengthening and staged impact with specialist or physiotherapy oversight.

Investigate the person as well as the bone. Recurrent, high-risk or insufficiency injury may justify FBC, renal and liver profile, calcium, phosphate, alkaline phosphatase, 25-hydroxyvitamin D, thyroid testing, coeliac assessment and reproductive hormones guided by history. DXA and fracture-risk assessment are particularly relevant with fragility, amenorrhoea, prolonged low energy availability, glucocorticoids or older age. Treat confirmed deficiencies and osteoporosis through current pathways; a single generic supplement dose is unsafe across renal disease, malabsorption, pregnancy and severe deficiency.

Return is criteria based, not calendar based. Daily walking and site palpation should be pain free; range, calf or hip strength and movement control should approach the other side. High-risk lesions often need imaging evidence of healing. Reintroduce impact in small increments with rest days, reverting if focal pain returns during or the next day. Adjust footwear, surface and training errors, restore adequate energy and protein, and plan surveillance during future high-load blocks.

Key points

Stress injury is a continuum from bone stress response to visible crack; load-related focal pain and tenderness can precede radiographic change by weeks.
Classify mechanism as fatigue injury in normal bone or insufficiency injury in weakened bone, then search for training, nutrition, endocrine, medicine and bone-density contributors.
Immediately unload suspected high-risk sites: femoral-neck tension side, anterior tibial cortex, navicular, talus, proximal fifth metatarsal and patella need urgent specialist assessment.
Obtain targeted radiographs initially because they identify a completed fracture and alternative pathology, but do not use normal early films to exclude a clinically important stress injury.
MRI is the preferred definitive test when suspicion persists because it detects marrow and periosteal stress response, fracture line and surrounding tissue without ionising radiation.
Use CT selectively to define a cortical line, navicular or fifth-metatarsal anatomy, delayed union and surgical planning; bone scintigraphy is sensitive but less specific and uses radiation.
Treatment starts with site-specific load reduction, pain-free cross-training when safe and correction of energy availability, calcium and vitamin D deficiency, menstrual or gonadal disturbance and biomechanics.
Return to impact only after daily activity and focal examination are pain free, high-risk healing is confirmed when required, strength and mechanics recover, and load increases gradually without recurrent symptoms.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Fatigue loading

Repetitive submaximal load exceeds remodelling capacity in otherwise normal bone, commonly after abrupt increases in running, marching, jumping, surface hardness or training frequency.

Insufficiency loading

Normal daily load fractures weakened bone in osteoporosis, osteomalacia, inflammatory disease, endocrine disorder, renal disease, prolonged glucocorticoid exposure or postpartum skeletal loss.

Low energy availability

Inadequate dietary energy relative to exercise disrupts reproductive, thyroid and bone physiology in all sexes and impairs remodelling, recovery and performance.

Biomechanical concentration

Cavus or planus alignment, leg-length difference, reduced calf capacity, poor technique and unsuitable footwear concentrate repeated force at vulnerable sites.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Remodelling imbalance
Osteoclastic resorption temporarily weakens repeatedly loaded bone; without sufficient recovery, microcracks coalesce faster than osteoblasts can restore structure.
2
Stress reaction continuum
Marrow and periosteal oedema precedes a visible cortical crack, so symptoms and MRI abnormalities can appear before radiographic fracture.
3
Tension-side propagation
Tensile forces distract a cortical defect, making superior femoral-neck and anterior tibial injuries less likely to heal under continued loading.
4
Vascular vulnerability
Navicular central bone and proximal fifth-metatarsal watershed regions have limited healing biology, increasing delayed union, nonunion and refracture.
5
Systemic skeletal deficit
Low oestrogen or testosterone, vitamin D deficiency, malabsorption and glucocorticoids reduce mineralisation or bone mass, turning ordinary load into injury.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Low-risk tibial pattern

Diffuse posteromedial tibial load pain or a focal compression-side reaction without anterior cortical defect commonly improves with graded unloading and biomechanical correction.

High-risk anterior tibia

Focal anterior mid-shaft tenderness and the radiographic dreaded black line reflects tension-side failure with substantial delayed-union risk.

Femoral-neck stress injury

Deep groin or thigh pain, painful hip rotation and antalgic gait in an endurance or low-bone-density context requires immediate protected loading and MRI.

Navicular stress injury

Poorly localised midfoot pain with focal dorsal navicular N-spot tenderness is easily missed on radiographs and has vulnerable central healing.

Metatarsal stress pattern

Focal shaft tenderness and swelling after a load increase commonly affects second or third metatarsals; proximal fifth location indicates greater risk.

Systemic bone-health pattern

Multiple sites, minimal load, recurrent injury, weight loss or menstrual or gonadal symptoms indicate insufficiency or low energy availability rather than isolated training error.

Red flags requiring action

Deep groin pain, pain on hip rotation or an antalgic gait in a runner, military recruit, pregnant or recently postpartum person, or someone with osteoporosis may represent femoral-neck stress injury and requires immediate unloading and urgent MRI-based assessment.
Sudden increase in previously gradual pain, a crack, new inability to bear weight, deformity or swelling suggests propagation to a complete or displaced fracture and requires emergency imaging and orthopaedic review.
Anterior tibial focal pain, navicular dorsal tenderness, proximal fifth-metatarsal pain or talar pain is a high-risk pattern because tension, limited blood supply or joint consequences raise delayed-union and displacement risk.
Weight loss, restrictive eating, menstrual disturbance, low libido, recurrent injury, fatigue or reduced performance signals low energy availability or an endocrine disorder requiring confidential multidisciplinary assessment, not exercise advice alone.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
First-line targeted radiographsFirst stepFirst line
Why
Find completed fracture, cortical reaction, alignment change or alternative pathology.
Interpretation and limitations
Obtain at the symptomatic bone and adjacent joint; normal early films are common and do not end investigation when focal symptoms persist.
02
Preferred MRIPreferred
Why
Confirm and grade bone stress response before a cortical fracture becomes radiographically visible.
Interpretation and limitations
Marrow or periosteal oedema supports early injury and a fracture line raises grade; interpret distribution with symptoms to avoid overcalling incidental signal.
03
CT for cortical detail
Why
Define fracture line, sclerosis, displacement and bridging in anatomically complex or delayed-healing sites.
Interpretation and limitations
Use for navicular, anterior tibia, proximal fifth metatarsal, operative planning or union; CT is less sensitive than MRI for the earliest marrow response.
04
Bone scintigraphy
Why
Detect increased bone turnover when MRI is unavailable or multifocal assessment is required.
Interpretation and limitations
It is sensitive but less specific, provides less anatomy and uses ionising radiation, so correlate any uptake with targeted structural imaging.
05
Targeted metabolic blood tests
Why
Identify mineral, renal, thyroid, malabsorptive or gonadal contributors.
Interpretation and limitations
Select tests from mechanism, recurrence and history rather than ordering a uniform panel; interpret vitamin D, calcium and hormones with clinical and reproductive context.
06
DXA and fracture-risk assessment
Why
Quantify bone density and support osteoporosis decisions in insufficiency or recurrent injury.
Interpretation and limitations
Use age- and sex-appropriate interpretation, noting that athletes can have clinically important low bone density without meeting an older-adult osteoporosis threshold.
07
Nutrition and energy assessment
Why
Identify low energy availability and deficiencies that impair bone remodelling.
Interpretation and limitations
Use confidential dietetic and medical assessment of intake, expenditure, weight trajectory, menstrual or gonadal function and eating-disorder risk rather than a screening score alone.
08
Healing assessment
Why
Determine readiness to advance load and investigate persistent pain.
Interpretation and limitations
Clinical recovery guides lower-risk injury; high-risk sites, ongoing tenderness or delayed progress commonly require repeat radiograph, CT or MRI before impact resumes.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Muscle or tendon overload

Diffuse pain linked to contraction or stretch without focal bony tenderness may indicate strain or tendinopathy, although both can coexist.

Medial tibial stress syndrome

Longer posteromedial tibial tenderness without a focal high-risk cortical point favours periosteal overload rather than a discrete fracture.

Bone tumour or infection

Night pain, rest pain, fever, systemic symptoms, destructive imaging or an atypical lesion requires urgent oncological or infection evaluation.

Joint or referred pain

Labral, arthritic, sacroiliac or lumbar pathology can cause groin or limb symptoms and needs regional examination when bone imaging is negative.

Acute occult fracture

A single traumatic event in osteoporotic bone may create an insufficiency fracture with similar MRI findings but different immediate trauma and falls needs.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01UrgentUnload a high-risk siteFirst stepPain and examination suggest femoral-neck, anterior tibial, navicular, talar, proximal fifth-metatarsal or another high-risk stress injury.

1Stop impact immediately, provide crutches and site-appropriate non-weight bearing or protected loading and avoid provocative hop testing.
2EscalationObtain targeted radiographs and urgent MRI despite normal films, escalating acute inability to bear weight or deformity as completed fracture.
3Arrange early orthopaedic or specialist sports review to decide immobilisation, fixation and imaging surveillance from site and grade.
4Screen simultaneously for low energy availability, pregnancy or lactation, medicines and metabolic bone disease without delaying fracture protection.

02Low riskRestore capacity under controlled loadImaging and specialist assessment define a stable low-risk bone stress injury.

1Remove painful impact and use a boot or crutches only as needed to make daily activity pain free while preserving safe conditioning.
2Address training progression, surface, footwear, strength, biomechanics, sleep and adequate energy, protein, calcium and vitamin D status.
3Progress from pain-free daily walking to strengthening, then short impact intervals separated by recovery days under a written plan.
4Step back and reassess if focal pain returns during exercise, persists the next morning or examination tenderness fails to improve.

03SystemicTreat the reason bone failedInjury is recurrent, multifocal, insufficiency-related or accompanied by nutritional, menstrual, gonadal or fragility features.

1Take a confidential dietary, endocrine, medicine, gastrointestinal, renal, reproductive and fracture history and assess physiological stability.
2Order targeted laboratory, DXA and fracture-risk investigations and refer to dietetics, endocrinology, bone health or eating-disorder care as indicated.
3Replace confirmed deficiency and treat osteoporosis through current condition-specific guidance, accounting for renal function, pregnancy and future fertility.
4Coordinate training restriction and return with the patient, coach or employer only with appropriate consent and measurable health and bone criteria.

Key medicines and prescribing safety1 treatment · regimens, roles and cautions

Can relieve pain during protected daily activity without using symptom suppression as a return-to-impact test.

Paracetamol for short-term pain

If analgesia is needed, give 1 g orally up to four times daily with at least 4 hours between doses and no more than 4 g in 24 hours; reduce the maximum for body weight under 50 kg, frailty, malnutrition or hepatic risk.

Count combination products and liver and alcohol risk; regular analgesia that masks focal pain can defeat load monitoring, and escalating rest pain requires diagnostic review rather than stronger routine medication.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Complete fracture and displacement

Continued impact can propagate a stress injury; displaced femoral-neck fracture risks avascular necrosis, nonunion and major reconstructive surgery.

Delayed union or nonunion

High-risk anatomy, smoking, poor energy availability and premature return to load can leave persistent pain and require fixation or grafting.

Recurrent multifocal injury

Uncorrected training error, endocrine disease, low energy availability or low bone density produces repeated injuries at new sites.

Deconditioning and psychological harm

Prolonged restriction without alternative training or support can cause muscle loss, isolation, anxiety and unsafe concealment of symptoms.

Chronic pain and lost participation

Incomplete rehabilitation, fear and persistent biomechanical overload can prevent return to sport, military work or independent mobility after union.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Record pain during daily activity, focal tenderness and next-day response rather than relying only on pain during a supervised session.
Repeat imaging according to anatomical risk and grade, using structural healing for high-risk sites before impact or unrestricted load advances.
Track weight trajectory, dietary adequacy, menstrual or gonadal recovery, fatigue, mood and performance with consent and appropriate multidisciplinary support.
Review calcium, vitamin D, endocrine or osteoporosis treatment against the identified disorder, renal function, pregnancy plans and adherence rather than indefinite empirical supplementation.
Measure site-relevant range, strength, hopping or running mechanics only when safe, and compare gait and functional capacity with the unaffected side.
After return, monitor weekly load, surfaces, footwear, recovery days and recurrent focal pain, especially during rapid training or occupational increases.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

Normal films are time dependent

Radiographic sensitivity improves only after cortical or periosteal response develops, while MRI can show the earlier remodelling failure.

Site outweighs pain score

Mild groin or navicular pain can represent a higher-consequence injury than severe pain at a biologically favourable fibular site.

RED-S affects every sex

Low energy availability can suppress reproductive and metabolic function without low body weight or an obvious eating disorder.

Hop tests can cause harm

Provocative impact is inappropriate when femoral-neck or another high-risk lesion is plausible and cannot safely rule it out.

MRI grade is not destiny

Imaging severity informs prognosis, but anatomical site, symptoms, nutrition, endocrine health and adherence determine actual recovery.

Return needs next-day data

A session tolerated without pain can still exceed bone capacity if focal symptoms recur later that day or the following morning.

11Common pitfallsFrequent interpretation and management errors.

01
Reassuring a patient with focal load pain because early radiographs are normal.
02
Encouraging hop testing or continued running before a high-risk femoral-neck or navicular injury is excluded.
03
Calling injury an overuse problem without assessing energy availability, menstrual or gonadal function, medicines and metabolic bone disease.
04
Using a fixed number of rest weeks instead of site, grade, clinical recovery and imaging criteria to guide return.
05
Prescribing generic vitamin D or calcium indefinitely without confirming need, renal safety and pregnancy context.
06
Allowing analgesia to mask pain during load progression or failing to act when symptoms return the following day.