In the latest in our series from Pulse Live talks, GP and registrar in Sports and Exercise Medicine Dr Soo Yit Gustin Mak discusses bone stress injury
What is bone stress injury (BSI)?
BSI is an overuse injury where repeated mechanical loading of the bone results in damage to the bone, with an imbalance between formation and removal of load induced damage.1 Time is needed for remodelling. Damage occurs when not enough time is allowed between loads for recovery. If a bone stress injury continues to be loaded and is not managed, this can lead to a stress fracture and eventually a complete fracture.
The weight bearing bones with the highest incidence of BSI are the tibia, metatarsals and fibula. However, BSI can affect almost any bone, depending on where mechanical loading occurs. For example, rowers put load on their rib cage. Poorly managed BSI can result in malunion and avascular necrosis. Surgery may then be required.
Risk factors for BSI1,2
Intrinsic risk factors include:
- BMI less than 19
- Female sex
- Age (increases with age)
- Muscle weakness and lack of flexibility
- Young age (skeletally immature)
- Osteoporosis
- Biomechanical factors
- Genetic, endocrine and metabolic conditions
Extrinsic risk factors include:
- Excessive load or rapid progression of increase in exercise that loads the bones
- Inappropriate or ill-fitting shoes and equipment
- Temperature (hot, cold, humid)
- Smoking
A related issue is low energy availability leading to Relative Energy Deficiency in Sport (REDs). This could be due to inadvertent under fuelling, disordered eating behaviour or an eating disorder. This is a condition where fuelling does not meet the body’s needs, with multisystem effects. This happens in both females and males. In females of reproductive age who are not on contraception, a loss or change of normal periods raises suspicion of this condition. If not clinically diagnosed and managed appropriately, REDs can have a devastating impact on bone health.3,4
How common is it?
Data on BSI comes mostly from athletic and military populations.5,6,7 Lifetime prevalence of stress fractures is reportedly 10% in athletes but teenagers may be at more risk of BSI (age 15-19), representing the largest proportion afflicted (42.6%).6 In addition, recurrence rate can be as high as 21%.6,7
Some sports including gymnastics are associated with higher risks of this injury. This may be because of the emphasis on lean physique in aesthetic sports.
Key points in the history
When assessing a potential BSI, ask about:
- Physical activity levels. What type of activity does the patient do, how frequently, at what intensity and duration.
- Over what time period?
- Any sudden increase or changes to physical activity, and any new activity.
- Pain at rest or during the night.
- Risk factors for abnormal bone health.
Pain is likely to start when weight bearing activity starts. As pathology progresses, the patient may experience pain on reduced load, for example when walking.
Examination
Key bony landmarks are close to the skin and therefore easy to palpate. Look for localised bony tenderness. Redness, swelling and warmth are occasionally present.
In deeper bones such as the femur, use the hop test and fulcrum test. If the patient reproduces the pain by hopping on the involved leg, the hop test result is considered positive, with a reported sensitivity of 70%.7 In the fulcrum test, with the patient seated, the examiner places one of his arms under the symptomatic thigh. Gentle pressure is applied on the knee with the opposite hand. Pain reproduced at the point of the fulcrum under the stress fracture is a positive test.9 Check for extension with rotation of the spine if you suspect bone stress injury in the spine (pars interarticularis – lies between superior and inferior articular process at each vertebral level). This can happen to dancers and bowlers in cricket.1
Red flag areas 1
These areas are prone to delayed or non union and therefore are more likely to progress to a high risk fracture:
- Femoral neck
- Anterior cortex tibia
- Medial malleolus
- Talus (lateral process)
- Navicular
- Proximal diaphysis of the 5th metatarsal
- Base of 2nd metatarsal
- Great toe sesamoids
- Pars interarticularis of lumbar spine
- Pelvis
Investigations
Radiographs have poor sensitivity (15-35%) in early stage injuries until late along the bone stress continuum (30-70%).9 However, radiography is accessible so is often used as the first-line investigation.
MRI remains the recommended first line investigation for bone stress injuries. It has high sensitivity in detecting soft tissue, bone and marrow pathophysiological changes associated with BSI such as periosteal or adjacent soft tissue oedema or band like bone marrow oedema suggestive of bone stress injury. DEXA scans should be considered if risk factors of osteoporosis are present. Consider requesting blood tests including calcium, vitamin D, thyroid function, iron studies and a coeliac screen.11,12
Management
Manage pain with analgesia. Where necessary advise smoking cessation as this can impact recovery.1
Where the area affected is high risk, refer urgently to A&E as patients will need to be managed with protected weight bearing with crutches until the diagnosis is confirmed. Thereafter, an individualised management plan will be suggested depending on the patient’s diagnosis and multiple factors.
For low risk areas, recommend offloading in the early stages. This could mean doing less/stop impact activities or just reducing activity level, eg, walking but with supportive shoewear, using pain to guide the patient. The patient can progress to modified activity and gradually resume activity, using pain to guide activity levels, with a referral to a specialist sports physiotherapist.
Avoid NSAIDS as there is evidence to suggest that this affects prostaglandins needed for normal bone turnover and healing.12
In the longer term, review dietary intake of calcium and vitamin D accordingly. Recommend strength training to reduce risk of bone loss density with ageing.10
References
1. Brukner P, Clarsen B, Cook J et al. Brukner and Khan’s Clinical Sports Medicine 5th edition Vol 1. Injuries. McGraw-Hill Education
2. Greeves J, Beck B, Nindl B et al. Current risk factors and emerging biomarkers for bone stress injuries in military personnel. Journal of Science and Medicine in Sport Vol 26 (1): S14-S21
3. Relative Energy Deficiency in Sports. Trainbrave.org
4. Mountjoy M, Ackerman KE, Bailey DM, et al. 2023 International Olympic Committee’s (Iconsensus statement on Relative Energy Deficiency in Sport (REDs). Br J Sports Med 2023;57(17):1073-97
5. Cosman F, Ruffing J, Zion M et al. Determinants of stress fracture risk in United States Military Academy Cadets. Bone 2013:55,2,359-66
6. Beck B, Drysdale L. Risk Factors, Diagnosis and Management of Bone Stress Injuries in Adolescent Athletes: A Narrative Review. Sports (Basel) 2021;9:52
7. Bennell KL, Malcolm SA, Thomas SA, Reid SJ, Brukner PD, Ebeling PR, Wark JD. Risk factors for stress fractures in track and field athletes. A twelve-month prospective study. Am J Sports Med 1996 Nov-Dec;24(6):810-8
8. Avrahami D, Pajaczkowski JA. Femoral neck stress fracture in a female athlete: a case report. J Chiropr Med 2012 Dec;11(4):273-9
9. Fulcrum test, Physiopedia. Link
10. Samin K. Stress fracture. Radiopedia 2023 Radiopaedia.org Link
11. Robinson P, Campbell V, Murray A et al. Stress fractures: diagnosis and management in the primary care setting. British Journal of General Practice 2019:69(681);209-300
12. Smith R, Baldock J, FitzPatrick M, et al The incidence of undiagnosed coeliac disease in patients presenting with stress fracture to a tertiary referral centre. British Journal of Sports Medicine 2019;53:843
13. Wheeler P, Batt ME. Do non-steroidal anti-inflammatory drugs adversely affect stress fracture healing? A short review. Br J Sports Med 2005 Feb;39(2):65-9
