loading

INTRODUCTION:

Stress fractures occur when bone, typically in the lower extremities, is subjected to repeated mechanical stress that results in microscopic fractures. They often occur when the frequency or degree of physical activity is significantly increased; therefore, stress fractures are commonly seen among military recruits, athletes, and runners. Stress fractures can be classified as fatigue reaction stress fractures or insufficiency reaction stress fractures. A stress fracture occurs when the adaptive ability of the bone is unbalanced. Normal bone is constantly being remodeled by osteoclasts absorbing and osteoblasts laying down new bone. During military training, for instance, the body cannot adapt fast enough, so the bone develops microfractures. They occur as the result of repeatedly making the same movement in a specific region, which can lead to fatigue and imbalance between osteoblast and osteoclast activity, thus favoring bone breakage.

CAUSES AND SYMPTOMS:

Runners, soldiers, and dancers are the main victims of stress fractures. Stress fractures are mostly commonly diagnosed in the tibia, followed by the metatarsals (especially the second and third metatarsals) and by the fibula. The factors associated with increased risk of development of stress fractures can be divided into extrinsic and intrinsic factors. This makes stress fractures multifactorial (1). Abrupt increases in the intensity and volume of training are often enough for lesions to develop. The quality of the training track may also be a risk factor, when it is uneven, irregular, or very rigid. Lastly, if the athlete’s fitness level is insufficient for the sports movement or functional technique, this may lead to injury, sometimes without the number of repetitions having been very high. The intrinsic factors relate to possible anatomical variations, muscle conditions, hormonal states, gender, ethnicity, or age.

Inadequate nutritional intake may alter bone metabolism and predispose toward appearance of stress fractures. Furthermore, rigid pes cavus, discrepancy of the lower limbs, short tibia, genu valgum, increased Q angle, body mass index lower than 21 kg/m2 and short stature should also be taken into consideration in analysing the risk factors for stress fractures. Women are more at risk. At first, the pain associated with a stress fracture, but it tends to worsen with time. The tenderness usually starts at a specific spot and decreases during rest. Also could be present swelling around the painful area. 

Diagnosis:

Physical examination of stress fractures is very sensitive but unspecific. In addition, the skipping rope test (hop test) can be used: this consists of asking the patient to hop on the spot while putting weight on the limb that is under investigation. The test is positive when it triggers strong or incapacitating pain in the region injured. Some laboratory tests may be useful in investigating stress fractures: serum levels of calcium, phosphorus, creatinine and 25(OH)D3. Nutritional markers should be requested in the presence of clinical conditions of weight loss and anorexia. Simple radiography (X-ray) is the initial imaging examination because of its ease of access and low cost. However, it has a high false-negative rate, given that the alterations caused by stress fractures only appear on such examinations at a late stage (two to four weeks after the start of the pain). Magnetic resonance imaging (MRI) is the most sensitive and specific imaging examination for diagnosing stress fractures. The abnormalities caused by the fracture can be identified one to two days after the start of the symptoms (2).

Treatment:

Prevention of new episodes is achieved through modifying activities, correcting sports movements, changing sports equipment, changing training locations that might be favouring bone overloading, changing nutritional habits, recognizing hormonal, anatomical and muscle strength alterations and recognizing low cardiomuscular conditioning. Treatments for stress fractures are based on prevention of new episodes and on recovery of the injured area. 

The treatments for these injuries comprise diminution of the overloading on the site affected, medication for pain control and physiotherapeutic rehabilitation. Immobilization is only rarely used for treating stress fractures because of its deleterious effects on muscles, tendons, ligaments, and joints. However, there are some specific types of fracture for which immobilization is fundamental for obtaining appropriate conditions for a cure: this is the case for the navicular bone, sesamoids, patella and posteromedial region of the tibia. High-risk fractures commonly evolve to non-consolidation of the bone and surgical intervention by an orthopaedist becomes necessary.

Some new types of therapy for stress fractures are being studied. In vitro studies have demonstrated that administration of 100% oxygen is capable of stimulating osteoblasts and consequently bone formation. Bisphosphonates suppress bone reabsorption and inactivate osteoclasts through their bonding with calcium phosphate crystals (3).


Resources:

  1. Cosman F, Ruffing J, Zion M, Uhorchak J, Ralston S, Tendy S, McGuigan FE, Lindsay R, Nieves J. Determinants of stress fracture risk in United States Military Academy cadets. Bone. 2013 Aug;55(2):359-66.
  • Ishibashi Y, Okamura Y, Otsuka H, Nishizawa K, Sasaki T, Toh S. Comparison of scintigraphy and magnetic resonance imaging for stress injuries of bone. Clin J Sport Med. 2002 Mar;12(2):79-84.
  • Raasch WG, Hergan DJ. Treatment of stress fractures: the fundamentals. Clin Sports Med. 2006 Jan;25(1):29-36, VII.

Write a Reply or Comment

Your email address will not be published. Required fields are marked *