Thread by @DrJN_SportsMed

Stress fractures - a detailed thread 🦴🦴🦴

I thought I'd put together an overview & some clinical nuggets from the 'coal-face'

First up, I prefer to call them 'bone stress injuries' - majority don't have a # line on imaging & the language can be scary / nocebic for some

Pathophysiology & risk factors

Stress fractures-
Occur in normal bone that is placed under abnormal / persistent load & strain ('training / sporting error')

Insufficiency fractures-
Occur in bone that is under normal strain but is structurally vulnerable eg metabolic conditions

In reality, can be a combination of both to varying degrees - not 'black & white'

Special mention goes to RED-S which often underpins BSI in athletes - men & women!

Ask about relationship with food (past & present) & menstrial history - periods are a barometer of athlete health

At a granular level, bone physiology, its hormonal control & homeostasis is complex - but the fundamentals are pretty straight forward ⬇️

Grading

Fredericson classification originally created for Medial Tibial Stress Syndrome (MTSS) - now extrapolated to other BSIs

Is it helpful?🧐

I occasionally see high grade injuries with minimal pain - & low grade stress reactions with significant symptoms & functional loss

However, generally if cortical involvement with fracture line = significant injury & correlates with extended RTP / running timescales

A useful platform for discussion with patient around severity of injury and respecting the injury & realistic timescales

High vs Low risk BSI

Some stress #s need to be treated with extra respect & caution - see table

These are typically under sustained high strain coupled with relatively poor blood supply

These are more likely to go through delayed union & take longer to recover - or indeed even need early orthopaedic opinion - tension / lateral side neck of femur is a good eg

Keep them on your clinical radar & assess specifically for them - lower threshold for imaging

Presentation

Gradual onset with persistent impact activity - but occasionally patient describes acute onset pain/ 'crack'

Pain on impact / 'first step' - tendon conditions often ‘warm up’ - unusual with BSI

Some with lower grade BSI can often run through it, but ⬇️performance

Rest & night pain when high grade

Ache, throb at rest - sharp, shooting under load - pelvic & proximal femur BSIs can feel 'neural' & refer into lower limb

Description of loss of power output, control, heaviness

Assessment

Lower limb & pelvic - 'Hop test' invariably positive - shut down, reduced power output

Sacral stress # - SIJ provocation tests

FADIR test positive for pubic & neck of femur BSI

Swelling & oedema (esp foot & ankle) around bony tenderness site in absence of trauma

Imaging - X-ray

X-rays ➡️poor sensitivity eg ~ 85% of pelvic stress #s are missed on plain films

More likely to pick up a BSI in later stages (eg 4 weeks+) due to callus formation

But better than nothing, esp if suspecting high grade high risk BSI eg ant tibial

MRI

Close to 100% sensitivity & the modality of choice

It picks up medullary bone oedema (earlier stress reaction) which X-ray & CT can't

It's more sensitive than 2 phase bone scan - plus bone scan non-specific

It also assesses periosteal & wider soft tissue involvement

MRI VIBE sequences ('pseudo CT') are excellent for detailed assessment of pars stress injuries

https://twitter.com/DrJN_SportsMed/status/1404740855756431362?s=20

This can be repeated to assess pars bony healing which takes longer than other BSIs (~3-6 months)
journals.assaf.org.za/index.php/sajs…

CT

Misconception re CT being accurate at identifying stress

Excellent at picking up & delineating high grade cortical disruption or long-standing changes eg callus formation / periosteal changes

But it's not a first line modality - MRI is gold standard

Lower threshold for using CT alongside MRI in high risk BSI

Useful where concern re:

Fracture configuration or cortical involvement underestimated on MRI

https://twitter.com/DrJN_SportsMed/status/1653786457436307456?s=20

Healing status / delayed union

Ruing out differential diagnosis eg tumour, osteomyelitis

Ultrasound

A quick useful tool at the point of care, time efficient

Can pick up periosteal reaction, callus formation, local soft tissue swelling & inflammation

Like x-ray & CT, won't pick up medullary bone oedema

On balance probably more sensitive than x-ray

Management

Ideally an MDT approach best esp if RED-S part of the picture - see slide below

Communication key - ? SEM led

Pharmacological Rx 💊💊- specialist decision in difficult cases eg bisphosphonates, teriparatide, transdermal oestrogen (RED-S)

Nutritional & dietary modifications - eg improving macro / calorie intake in cases of low energy availability (LEA)

Vitamin D

Other adjuncts eg shockwave therapy, LIPUS - controversial

Rehab fundamentals

Return to running & load progressions guided by pain levels & function

Beware 'lag phenomenon' when assessing pain response / flare on⬆️load - delay over 2-3 days

Generally 12-16 weeks RTR

<8 weeks seems a recipe for recurrence & back to 'square 1'

Challenge 😤🙄 the small number of patients who have low levels of pain - or pain settles v quickly with early offload - but high grade stress radiologically

In these cases seems sensible to respect physiology & set arbitrary number of weeks before moving into RTR

Some clinicians might not agree with this & have a more pragmatic approach

@rwilly2003 paper has suggested that with MTSS, if pain free for 5 days can begin graded RTR

So clearly can't be rigidly prescriptive / recipe based - every patient different due to personal factors ++

Tips:

Time scales variable
Respect physiology
Not ‘one size fits all’
Step count?
Pragmatic approach to cross training
Parallel S&C programme
Education
Alter G – graded exposure?

Why aren't they getting better?

Compliance aside - misdiagnosis might be the cause -

eg rheumatological - enthesopathy with florid bone oedema

Osteoid osteoma tumour - eg proximal femur & calcaneum - here CT will help differentiate

https://twitter.com/DrJN_SportsMed/status/1628905076616994819?s=20