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  • Writer's pictureJames McMurray

What is a Stress Fracture?


"March foot" was the first name given to stress fractures when they were initially reported by Prussian soldiers in 1855. They were experiencing metatarsal stress fractures with soldiers complaining of foot pain and swelling (McCormick, 2012; Behrens, 2013). This lead to Julius Wolff (1836-1902), a German surgeon, to propose that bones remodel and adapt to the loads placed on them (Frost, 1994). Forty years later, in 1897, the first radiographic evidence of metatarsal stress fractures of military recruits were produced, only 2 years after the physicist Wilhelm Röntgen discovered X-Rays in 1895. The earliest known diagnosis of a stress fracture in an athlete occurred in 1934 which was on the femoral shaft (thigh bone). It was until 1956, 100 years after its initial reporting in military recruits, that the first comprehensive study with a series of athletes with fibular stress fractures in 1956 (Devas, 1956). It most likely took this long to produce quality research in runners due to the revival of middle-distance running events in the Olympics in the middle of the 19th century increasing the popularity of running of this time, along with the development in X-Ray technology by medical pioneers such as Marie Currie inventing the portable X-Ray machine in 1917. By 1925 about a quarter of all patients admitted to the hospital had some sort of an X-ray examination performed in the US (Howell, 1995).


What Causes Stress Fractures?


Repeated mechanical stress on bones, typically in the lower extremities, leads to stress fractures, which are microscopic fractures. These fractures often happen when there's a significant increase in the frequency or intensity of physical activity, making them common among military recruits, athletes, and runners. Stress fractures can be categorized into two types: fatigue reaction stress fractures and insufficiency reaction stress fractures.


Fatigue reaction stress fractures occur due to repetitive and excessive strain on structurally normal bone, surpassing the remodeling process, for example a new runner who has increased their volume of training far too quickly. On the other hand, insufficiency reaction stress fractures happen when normal stress and straining affect a bone with impaired formation, for example this could happen in the elderly population with reduced bone mineral density, or in an under fuelled athlete.


Normal bone undergoes constant remodeling, with osteoclasts reabsorbing and osteoblasts depositing new bone. During over-intense weight bearing activities, the osteoclast activity increases too much and becomes greater than the osteoblast activity, in simple terms bone breakdown is greater that new bone development, leading to the development of microfractures in the bone. If this level of activity persists, these microfractures can progress to a full-blown fracture.


Risk Factors


As outlined by McCormick (2012) the intrinic and extrinsic risk factors are as follows:


Intrinsic factors:

  • Poor physical conditioning

  • Female

  • Hormonal disorder

  • Menstrual disorder

  • Poor bone density

  • Reduced muscle mass

  • Relative energy deficiency syndrome (RED-S)

  • Genu valgum knees (only in knee osteoarthritis (Vaishya, 2018))

  • Clinical leg length discrepency

Extrinsic factors:

  • High-impact sports activities like running, jumping

  • Abrupt increase in physical activity

  • Irregular or angled running surface

  • Poor footwear

  • Running shoe wear older than 6 months

  • Deficient vitamin D and calcium intake/absorbtion

  • Smoking



The most common risk factor is an abrupt increase in activity. A longitudinal study (Pihlajamäki, 2019) of 5000 Finnish male military recruits that reported regular physical activity (> 2 times/week) before entering the military had significantly fewer fatigue fractures, meaning that those recruits that do not exercise prior to military service are more at risk of developing a stress fracture. Regular physical activity before entering the service was the only strong protective factor in the study. Most fatigue fractures occurred in the first 3 months of military service. This demonstrates the importance of slow progressive overload which allows the body to adapt.


Common Sites


The most common sites for stress fractures are as follows:

  1. Metatarsals

  2. Tibia

  3. Tarsals

  4. Femur

  5. Fibula

  6. Pelvis


However, in female athletes, stress fractures of the pelvis and metatarsals are most common. 


Upper body stress fractures are rare but have been reported in gymnasts, weightlifters, and throwing athletes.  The clavicle, scapula, first rib and proximal humerus/shaft (thrower's shoulder), medial epicondyle (thrower's elbow), olecranon, and radial physis (gymnast's wrist) are the most common sites (Matcuk, 2016).


The most common stress fractures in runners specifically are: (Kahanov, 2015)

  1. Tibia (23.6%),

  2. Tarsal/navicular (17.6%)

  3. Metatarsals (16.2%)

  4. Femur (6.6%)

  5. Pelvis (1.6%)


Runners who average more than 25 miles a week are considered high risk and stress fractures account for nearly 16% of all injuries (Moreira, 2017).  However if you are an athlete who has trained for a number of years and accustomed to this volume of running this amount is unlikely to be an issue.


High Risk and Low Risk Factors


High risk stress fractures are those which have a higher tendency for nonunion or delayed union. These require prompt treatment and may require immobilisation to prevent complications and progression to a full fracture.


Could I have a stress fracture?


If you have started to experience pain while running on a bony area of the body which progressively gets worse during running, and may also have some of the risk factors mentioned above, you should see a health professional for an assessment to clear a diagnosis of a stress fracture.


Imaging is used to confirm the diagnosis. X-Ray can be used but with a sensitivity of 10% in the first 6 weeks of injury (meaning a low probability it can detect the facture) as the fracture is to small for the X-Ray to see and is more accurate once a callus has formed after 6-8 weeks. MRI on the other hand is much more accurate (sensitivity 86-100%). A CT scan maybe needed in the Sacrum and pelvis region which an MRI may not pick up as well.




Thanks for Reading


James McMurray

Sport and Exercise Health Science BSc

Physiotherapy BSc

 

Disclaimer:

This is not medical advice. The content is intended as educational content only. If you have any heel pain that is not getting better, then you should seek care of a medical professional.





References:

Behrens, S. B., Deren, M. E., Matson, A., Fadale, P. D., & Monchik, K. O. (2013). Stress fractures of the pelvis and legs in athletes: a review. Sports health, 5(2), 165–174. https://doi.org/10.1177/1941738112467423


Devas MB. Stress fractures of the fibula: a review of fifty cases in athletes. J Bone Joint Surg Br. 1956;38:818-829


Howell JD. Technology in the Hospital: Transforming Patient Care in the Early Twentieth Century. Baltimore, Maryland: Johns Hopkins University Press; 1995.


McCormick F, Nwachukwu BU, Provencher MT. Stress fractures in runners. Clin Sports Med. 2012 Apr;31(2):291-306.


Frost HM. Wolff's Law and bone's structural adaptations to mechanical usage: an overview for clinicians. Angle Orthod. 1994;64(3):175-88.


Matcuk GR, Mahanty SR, Skalski MR, Patel DB, White EA, Gottsegen CJ. Stress fractures: pathophysiology, clinical presentation, imaging features, and treatment options. Emerg Radiol. 2016 Aug;23(4):365-75


Moreira CA, Bilezikian JP. Stress Fractures: Concepts and Therapeutics. J Clin Endocrinol Metab. 2017 Feb 01;102(2):525-534.


Kahanov L, Eberman LE, Games KE, Wasik M. Diagnosis, treatment, and rehabilitation of stress fractures in the lower extremity in runners. Open Access J Sports Med. 2015;6:87-95.


Pihlajamäki H, Parviainen M, Kyröläinen H, Kautiainen H, Kiviranta I. Regular physical exercise before entering military service may protect young adult men from fatigue fractures. BMC Musculoskelet Disord. 2019 Mar 25;20(1):126.


Vaishya, R., Vijay, V., Agarwal, A. K., & Vaish, A. (2018). Single-stage Management of Advanced Bilateral Knee Osteoarthritis with Stress Fracture of Medial Malleolus. Journal of orthopaedic case reports, 8(1), 89–92. https://doi.org/10.13107/jocr.2250-0685.1014



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