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Stress Fractures
- June 15, 2017
- Posted by: Pieter Kroon
- Category: Uncategorized
This blog post will discuss a poorly understood entity- the stress fracture
Stress fractures are a common entity encountered across all patient demographics. The first case description of bone stress injuries was in Prussian military recruits who presented with metatarsal pain from marching—the “march fracture.”
The proper definition and pathophysiology of the stress fracture today is best understood as two contrary processes with a similar end result:
• The fatigue fracture is the result of an abnormal load upon normal bone. The patient population is usually younger, athletic, females>males
• The insufficiency fracture is the result of normal loading upon abnormal bone (osteopenia/osteoporosis) or metabolic bone disease. Common locations: sacrum, pubic rami, hip.
For the sake of this discussion we will stick to the fatigue fractures.
Etiology: multifactorial
Risk Factors
A systematic review by Wright et al. (2015) revealed a striking lack of evidence for any risk factors, but with 2 exceptions:
• Runners with a previous history of stress fractures have a 5 times higher risk of a future stress fracture.
• Female distance runners have a 2.3 times higher risk of developing bone stress compared to male distance runners.
Why is the evidence scant?
Prospective studies examining stress fractures are difficult to perform given the large populations that must be followed for long time periods, and thus, retrospective studies are often pursued, even though they are unable to establish a causal relationship.
Additionally, one could argue that the lack of available evidence may be secondary to the complex nature of stress fracture research in the running population. One of the complications in stress fracture research in runners is the interdependence of variables and how individual differences may influence response to confounding factors.
The individual nature of stress fracture risk, and thus, the need to identify risk factors to prevent them, is also clear when one considers athletes performing nearly identical training regimens within a team. While some athletes remain injury free, others develop soft tissue injuries (eg, tendinopathy), whereas other develop stress
fractures at different sites.
Prevalence of Stress Fractures
Stress fractures can affect almost any bone, but the vast majority (up to 95%) affect the lower extremity. A review by Liong and Whitehouse (2012) notes the following incidence of LE stress fractures:
Pelvis: 1.3-5.6% of stress fractures seen in athletes
Femur: 4.2-48%. More common in females, especially runners
Fibula: 1.3-12.1%
Tibia: most commonly involved bone, up to 50%
Tarsal bones: 10-25%
Healing Time Table
A systematic review by Hallee et al. (2015) compared the time to return to sport, activity and work after conservative or operative treatment of stress fractures of the tibia, navicular and fifth metatarsal.
The Take Away:
High-risk stress fractures of the lower leg are prone to be a career ending injury in athletes. Conservative therapy in anterior tibial stress fractures reported very low success rates and only a few athletes returned to their previous sports level.
Navicular and fifth metatarsal stress fractures seem to have an earlier return to sport after surgical intervention.
Tibia
Conservative treatment provides worrying outcomes since most patients did not return to their previous level of sport and a high-rates of non-union was found. Clinicians must keep these results in mind and explain the difficulties in anterior tibial stress fractures to their patients. Extensive follow-up of conservatively treated bone stress is advised in order to assess proper healing and to intervene if non-union occurs. Having a high index of suspicion is helpful as the reported time between onset of symptoms until the start of treatment is reported to be quite extreme in most cases, up to 36 months.
Navicular
Current data suggests that surgical intervention leads to an earlier return to sport (16.4 vs 21.7 weeks). Post-operative complications were rarely reported. Among conservatively treated patients, the complication rates were high, especially delayed unions and re-fractures.
A non-weight bearing conservative treatment of at least 6-weeks results in less treatment failures than conservative treatment without non-WB immobilisation.38 Therefore, this would be the conservative treatment of choice.
Proximal Fifth Metatarsal
Patients with this type of fracture must account for time away from sports of approximately 14 weeks. Significant differences could not be calculated; however, surgical treatment resulted in an earlier return to sport (13.8 vs 19.2 weeks). Union problems and re-fractures seem less prevalent after surgical treatment. Conservative treatment details were limited, consisting of WB and non-WB protocols. Unfortunately, evidence is still lacking to advise on one adequate method
Femur
Fractures of the neck of the femur can happen on the compression side (inferior portion of the neck) or the traction side (superior portion of the neck). Stress fractures on the compression side do well with conservative management whereas stress fractures on the traction side likely need surgical intervention. Failure to properly identify a femoral neck stress fracture can lead to complete fractures, avascular necrosis of the femoral head and other major complications, which may eventually require total hip arthroplasty and result in long-term disability.
Clinical findings indicative of a possible femoral stress fracture includes: groin pain, Trendelenburg gait, positive single leg hop test, positive patellar-pubic percussion test, and pinpoint tenderness on palpation of the neck of the femur.
Imaging
A systematic review by Wright et al. (2015) identified MRI as the most sensitive and specific imaging test for diagnosing stress fractures of the lower extremity. When MRI is available, bone scans are not recommended because of its low specificity and high dosage of ionizing radiation. Radiographs are likely to result in false negatives upon initial presentation, especially in the early stages of stress fractures, and in some cases may not reveal an existing stress fracture at any time.
See you all next time,
Pieter
The Manual Therapy Institute is a part-time, on-site orthopedic manual physical therapy certification and fellowship education program. To find out more about MTI, please see our website at www.mtitx.com
Reference
1. Clement et al. Exercise induced stress injuries to the femur. International Journal of Sports Medicine (1993);14(6):347-352
2. Liong SY and Whitehouse RW. Lower extremity and pelvic stress fractures in athletes. Br J Radiol. (2012);85(1016):1148-1156
3. Mallee WH et al. Surgical versus conservative treatment for high risk stress fractures of the lower leg (anterior tibial cortex, navicular and fifth metatarsal base: a systematic review. Br J Sports Med (2015);49 (6);370-376
4. Matcuk GR et al. Stress Fractures: pathophysiology, clinical presentation, imaging features and treatment options. Emergency Radiology (2016):23(4):365-375
5. Schneiders AG, Sullivan SJ, Hendrick PA, Hones BD, McMaster AR, Sugden BA, Tomlinson C. The ability of clinical tests to diagnose stress fractures: a systematic review and meta-analysis. JOSPT (2012) Vol42(9):760-71.
6. Wright AA et al. Diagnostic accuracy of various imaging modalities for suspected lower extremity stress fractures: a systematic review with evidence based recommendations for clinical practice. Am J Sports Med. (2016);44(1):255-263
7. Wright AA et al. Risk factors associated with lower extremity stress fractures in runners: a systematic review and meta-analysis. Br J Sports Med. (2015):49(23):1517-23
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