A stress fracture is one type of incomplete fracture in bones. It is caused by “unusual or repeated stress” and also heavy continuous weight on the ankle or leg.This is in contrast to other types of fractures, which are usually characterized by a solitary, severe impact.
It could be described as a very small sliver or crack in the bone; this is why it is sometimes dubbed “hairline fracture”. It typically occurs in weight-bearing bones, such as the tibia (bone of the lower leg), metatarsals (bones of the foot), and less commonly, the femur.
It is a common sports injury, and most cases are associated with athletics.
Stress fractures usually have only a few symptoms. A stress fracture could present as a generalized area of pain and tenderness associated with weight bearing. Usually when running, a stress fracture in the leg or foot will cause severe pain at the beginning of the run, moderate pain in the middle of the run, and severe pain at the end and after the run. After running it may just feel likeshin splints, but in a very concentrated area. Occasionally, darkening or bruising will be seen at the site.
-gradual onset-a dull ache which progresses to sharp pin point pain
phase 1 : pain during activity
phase 2 : pain during and after activity
phase 3 : constant pain – even with the first steps in the morning before any activity
-usually no swelling
-repeated overloading-overuse. The stress on the bone is not afforded sufficient time to recover between periods of use.
-poor physical condition
-poor diet-lack of calcium
-structural condition of the foot
-change of training habits
-training too quickly; doing ¨ too much,too quickly¨
Bones are constantly attempting to remodel and repair themselves, especially during a sport where extraordinary stress is applied to the bone. Over time, if enough stress is placed on the bone that it exhausts the capacity of the bone to remodel, a weakened site—a stress fracture—on the bone may appear. The fracture does not appear suddenly. It occurs from repeated traumas, none of which is sufficient to cause a sudden break, but which, when added together, overwhelm the osteoblasts that remodel the bone.
Stress fractures commonly occur in sedentary people who suddenly undertake a burst of exercise (whose bones are not used to the task). They may also occur in Olympic-class athletes who do extraordinary quantities of high-impact exercise, in professional and amateur distance runners who run high weekly mileage, or in soldiers who march long distances.
Muscle fatigue can also play a role in the occurrence of stress fractures. In a runner, each stride normally exerts large forces at various points in the legs. Each shock—a rapid acceleration and energy transfer—must be absorbed. Both muscles and bones serve as shock absorbers. However, the muscles, usually those in the lower leg, become fatigued after running a long distance and lose their ability to absorb shock. As the bones now experience larger stresses, this increases the risk of fracture.
Previous stress fractures have been identified as a risk factor.
A stress fracture is best diagnosed after interview and examination by a physician. Investigations are not necessary to diagnose a stress fracture.
A stress fracture is so small that an X-ray can only detect the healing of the stress fracture ( the callus ) and not the fracture itself.It is better to take an initial X-ray as a baseline and a comparison X-ray 14 days later.
The most effective method of diagnosing a tress fracture is with a bone scan,where radioactive tracers are injected into the bloodstream and travel to the bone. If the bone absorbs the tracer,it will show as a ¨hot¨ spot and indicate a stress fracture. An MRI is also effective in showing bone abnormalities that X-ray fail to reveal.
If a stress fracture is suspected,it is recommended to stop the activity so the bony callus can form and begin to heal – usually 2 to 6 weeks,depending on the location of the fracture.
Stress fractures typically do no require casting,unless they are ignored and progress into a regular closed fracture.
A gradual return to activity is important.If activity is resumed too quickly,the stress fracture can return.
During recovery,corss training that does not put stress on the injury is recommended to maintain fitness levels.
If a stress fracture occurs in a weight-bearing bone, healing will be delayed or prevented by continuing to put weight on that limb. Most people don’t even know they have a hairline fracture until they hurt themselves again, then they have a broken bone. If left untreated, the broken bone can turn into an infection that can cause severe medical issues.
Rehabilitation usually includes muscle strength training to help dissipate the forces transmitted to the bones.
Bracing or casting the limb with a hard plastic boot or air cast may also prove beneficial by taking some stress off the stress fracture. An air cast has pre-inflated cells that put light pressure on the bone, which promotes healing by increasing blood flow to the area. This also reduces pain because of the pressure applied to the bone. If the stress fracture of the leg or foot is severe enough, crutches can help by removing stress from the bone.
One method of avoiding stress fractures is to add more stress to the bones. Though this may seem counter-intuitive (because stress fractures are caused by too much stress on the bone), moderate stress applied to the bone in a controlled manner can strengthen the bone and make it less susceptible to a stress fracture. An easy way to do this is to follow the runner’s rule of increasing distance by no more than 10 percent per week. This allows the bones to adapt to the added stress so they are able to withstand greater stress in the future.
Strengthening exercises also help build muscle strength in the legs. Strengthening these muscles will prevent them from becoming fatigued quickly, allowing them to absorb the strain of running for longer periods of time. Key muscles that need strengthening with lower leg stress fractures are the calves and the shin muscles. Runners often suffer from overuse injuries or repetitive stress injuries. These include stress fractures, stress reactions, tendinitis, meniscal tears, ITB Friction syndrome, and exacerbation of pre-existing arthritis. Stress fractures, if not diagnosed and treated, can develop into complete fractures.
Depending on a variety of factors (including weight, running surface and shoe durability), runners should replace their shoes every 300–700 miles to allow adequate mid-sole cushioning. A change in running surfaces can also help prevent stress fractures. However, it is also argued that cushioning in shoes actually causes more stress by reducing the body’s natural shock-absorbing action, increasing the frequency of running injuries.
During exercise that applies more stress to the bones, it may help to increase calcium and vitamin D intake, depending on the individual. Also, it is important to monitor diet, because nutritionplays a vital role in bone development. Some individuals are at risk of osteoporosis, and depending on the country in which medical care is being supplied, there may be an osteoporosis screening program available.
A study released by Creighton University has shown Calcium and Vitamin D supplementation, even over a short period, can significantly reduce stress fractures in female military recruits. The study results were reported on February 11, 2007 at the 53rd annual Orthopaedic Research Society meeting at the San Diego Convention Center.