Stress fracture

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Stress fractures are fractures induced by fatigue caused by repetitive stress over time. Instead of generating from one severe impact, a stress fracture is the result of accumulated trauma from repeated submaximal loading, such as running or jumping. Due to this mechanism, stress fractures are excessive injuries that often occur in athletes.

A stress fracture can be described as a small incision or fracture in the bone; and is sometimes referred to as "hairline fracture." Stress fractures are most common in burdened bones, such as the tibia (the lower leg bone), the metatarsal, and the navicular bone (leg bone). Less common are fractures to the femur, pelvis, and sacrum.

Video Stress fracture

Signs and symptoms

Stress fractures are usually found after a rapid increase in exercise. They are most often present as pain with an increased load with activity. The pain usually subsides with rest but may be constantly present with more serious bone injuries. Usually there is a local tenderness area in or near bone and general swelling to the area. Percussion or palpation to the bone may reproduce the symptoms. Anterior tibial stress fracture results in focal tenderness in anterior tibial crystals, whereas a posterior medial stress fracture may become tender on the posterior tibia boundary.

Maps Stress fracture

Cause

The bones continue to try to remodel and improve themselves, especially during sports where extraordinary pressure is applied to the bones. Over time, if sufficient stress is placed on the bone that drains the bone's capacity to remodel, the attenuated site - a stress fracture - may appear on the bone. Fracture does not appear suddenly. Occurs due to repetitive trauma, there is nothing sufficient to cause a sudden break, but which, when added together, floods osteoblasts that break the bone.

Stress fractures usually occur in people who are inactive who suddenly do exercises (whose bones are unfamiliar with the task). They can also occur in athletes who complete high volume workouts, high impact training, such as running or jumping sports. Stress fractures are also often reported in soldiers who line up long distances.

Muscle fatigue can also play a role in the occurrence of stress fractures. In runners, each step usually gives great strength at various points in the foot. Every surprise - acceleration and quick energy transfer - must be absorbed. Muscle and bone function as shock absorbers. However, the muscles, usually those in the lower legs, become tired after running long distances and lose their ability to absorb surprises. Because bones are now under greater pressure, this increases the risk of fractures.

A previous stress fracture has been identified as a risk factor.

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Diagnosis

X-rays usually do not show evidence of new stress fractures, but can be used 3 weeks after onset of pain when bone begins to break down. CT scans, MRIs, or 3-phase bone scans may be more effective for early diagnosis.

MRI seems to be the most accurate test.

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Prevention

Changing training biomechanics and training schedules can reduce the prevalence of stress fractures. Orthotic soles have been found to reduce stress fracture levels in military recruits, but it is unclear whether these can be extrapolated to the general population or athletes. On the other hand, some athletes argue that cushioning in shoes actually causes more stress by reducing the body's natural shock absorbing action, thereby increasing the frequency of running injuries. During exercise that is more emphasis on bone, this can help increase daily calcium intake (2,000 mg) and vitamin D (800 IU), depending on the individual.

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Treatment

For low-risk stress fractures, rest is the best management option. The amount of recovery time varies greatly depending on the location and severity of the fracture, and the healing response of the body. Complete rest and stirrups or walking braces are typically used for a period of four to eight weeks, although rest periods for twelve weeks or more are not uncommon for more severe stress fractures. After this period, activities can be gradually resumed as long as the activity does not cause pain. While bones may feel healed and unwell during daily activities, bone remodeling may occur for months after the injury is healed. The incidence of bone refraction is still a significant risk. Activities such as running or sports that put extra stress on the bones should only gradually resume. Rehabilitation usually includes muscle strength training to help remove the transmitted force to the bone.

With a severe stress fracture (see "prognosis"), surgery may be necessary for proper healing. This procedure may involve clamping the place of the fracture, and rehabilitation may take up to six months.

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Prognosis

An anterior tibial stress fracture can have a very poor prognosis and may require surgery. In radiographic imaging this stress fracture is referred to as "the dreaded black line." When compared to other stress fractures, anterior tibial fractures are more likely to develop to resolve tibial fractures and displacement. Superior femoral neck fractures, if left untreated, may develop into complete fractures with avascular necrosis, and should also be managed surgically. A proximal metadiaphyseal fracture of the 5th metatarsal (the center of the outer edge of the foot) is also notable for poor bone healing. This stress fracture heals slowly with significant refractive risk.

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Epidemiology

In the US, the annual incidence of stress fractures in athletes and military recruits ranges from 5% to 30%, depending on exercise and other risk factors. Women and highly active individuals are also at higher risk. This incidence may also increase with age due to age reduction in bone mass density (BMD). Children are also at risk because their bones have not reached full density and strength. Triad female athletes can also put women at risk as eating disorders and osteoporosis can cause bones to become very weak.

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Other animals

Dinosaur

In 2001, Bruce Rothschild and other paleontologists published a study examining the evidence for stress fracture in theropod dinosaurs and analyzing the implications that such injuries would have to reconstruct their behavior. Because stress fractures are due to their recurring events it may be caused by regular expressions of behavior rather than chance trauma. Researchers pay particular attention to evidence of hand injuries because dinosaur back legs will be more vulnerable to injuries received when running or migrating. Hand injuries, meanwhile, are more likely to be caused by struggling prey. Stress fractures on dinosaur bones can be identified by searching for bumps on the bones facing the front of the animal. When X-rays, these bulges often show the lines of empty space where the x-rays have a harder time to pass through the bone. Rothschild and other researchers noted that the "attenuation zone" seen under these x-rays is usually not visible to the naked eye.

The researchers described the phalanges of theropods as "pathognomonic" for stress fractures, meaning they are "characteristic and firmly diagnosed." Rothschild and other researchers examined and rejected the types of injuries and other diseases as the cause of the lesions they found on dinosaur bones. Lesions left behind by stress fractures can be distinguished from osteomyelitis without difficulty because of the lack of bone damage in stress fracture lesions. They can be distinguished from benign bone tumors such as osteoid osteoma by a lack of sclerotic perimeter. No interference from the internal bone architecture of the type caused by malignant bone tumors found among candidates of stress fractures. There is no evidence of metabolic disorders such as hyperparathyroidism or hyperthyroidism found in specimens.

After examining the bones of different types of dinosaurs, the researchers noted that Allosaurus had a much greater amount of bulge in the bones of the hands and bones of the leg than the Albertosaurus tyrannosaur, or the ostrich dinosaur Ornithomimus and Archaeornithomimus . Most of the stress fractures observed along the bones of the Allosaurus bone are limited to the ends closest to the hind legs, but are scattered across all three major digits in "statistically indistinguishable numbers ". Because the lower end of the third metatarsal will contact the ground first while the theropod runs it will bear most of the stress and must be most susceptible to suffering from stress fractures. The lack of such bias in the fossils examined shows the origin of stress fractures from sources other than running. The authors concluded that this fracture occurred during interaction with prey. They argue that such injuries can occur as a result of theropods that try to withstand prey struggling with their feet. The presence of stress fractures provides evidence for a very active predation-based feeding rather than a scavenging diet.

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References

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External links

Source of the article : Wikipedia