Fatigue fractures or stress fractures of the pelvic and femoral bones occur as a result of bone overload, not impact or injury. Bone overload essentially means repeated, prolonged, repetitive microtraumatization. As a rule, stress fractures occur in female athletes, but they can also occur simply in active young people.
Fatigue fractures or stress fractures are predisposed to several factors that can be divided into external and internal: external factors include shoes, the surface of the playing field or track and field tracks and the intensity of exercise, and internal factors include osteopenia (reduced bone strength) and various violations of the normal anatomy of the skeleton, for example, congenital varus (deviation inwards) deformity of the femoral neck. All these factors should be taken into account for the prevention of fatigue fractures. So, long-distance runners should wear shoes with soft, elastic soles and run on a not too hard surface. In addition, a gradual, rather than sudden increase in exercise load during exercise reduces the likelihood of any fatigue fractures.
Internal predisposing factors are more difficult to influence. Anatomical defects can be corrected with orthopedic devices. Osteopenia is more common in female athletes and is part of the so-called triad of athletes (which includes, in addition to osteopenia, an eating disorder and amenorrhea). It requires more active medical intervention and prescribing medications and a special diet.
In the area of the hip joint, there are fatigue fractures of the femoral neck, sacrum, pubic bone branch, sciatic bone, acetabular cavity and femoral head.
Fatigue fractures are very different from traditional traumatic fractures. For example, a hip fracture is diagnosed and treated in a completely different way, so now we will not dwell on this issue.
Depending on the location of the fatigue fracture, patients complain of pain in the lower back, buttocks, groin, hip, and even in the knee. At first, it appears after physical exertion, training, and then begins to occur during physical exertion and even during simple standing and walking. Patients do not recall any obvious injuries immediately preceding the appearance of pain.
The inspection is not very informative. Patients often spare a sore leg when walking. In fractures of the sacrum and pubic bone, palpation in the area of the fracture is painful; in fractures of the femoral neck, the point of greatest pain can not be found. In femoral neck fractures, the amount of movement in the hip joint (especially the amount of internal rotation) can be reduced due to pain. With sacral fractures, the Patrick test is positive (the patient, lying on his back, puts the foot of one foot on the knee of the other, and the doctor presses the knee of the bent leg to the couch, which is accompanied by pain in the lower back or buttocks). Fractures of the pubic bone may cause pain during pelvic compression.
To confirm or exclude osteopenia, athletes undergo a biochemical blood and urine test.
Stress fractures are incomplete (marginal) and complete, passing through the entire thickness of the bone. Changes on radiographs (sclerosis, clearings, cortical hypertrophy) may not appear for a long time, sometimes up to a month. Unfortunately, X-rays often show only complete fractures, but with good image quality, this method of investigation allows you to suspect a marginal stress fracture.
Radiograph of a complete stress fracture of the femoral neck
To study the sciatic bone, pelvic radiographs are required, at least in the direct posterior projection and oblique caudal projection (“pelvic entrance”), as well as an X-ray of the lumbosacral spine in the lateral projection. To study the pubic bone, pelvic radiographs are required in the direct posterior projection, oblique caudal (“pelvic entrance”) and cranial (“pelvic exit”) projections, and posterior oblique projection (according to Judet). To study the femoral neck, you need a pelvic X-ray in a straight posterior projection, a hip joint X-ray in a straight posterior projection, and a pelvic X-ray in a posterior bilateral projection with the patient’s legs bent and separated by 45° (in the frog position).
Computed tomography is of great value in the diagnosis of fatigue fractures. Tomograms show the same signs of fatigue fractures as radiographs: sclerosis, cortical hypertrophy, and a light fracture line. Scintigraphy of bones shows pockets of isotope accumulation at the site of fatigue fractures. Scintigraphy has a high sensitivity, but low specificity for fatigue fractures — the frequency of false positive results reaches 30%.
Unlike scintigraphy, magnetic resonance imaging is not only highly sensitive, but also a highly specific method that allows you to distinguish fatigue fractures from the physiological response of the bone to high stress.
Magnetic resonance imaging showing a marginal stress fracture of the femoral neck
The diagnosis of fatigue fractures (stress fractures) is very important, and this diagnosis should be the first among suspects in hip pain in young active people. Fatigue fractures of the femoral neck are especially dangerous. The fact is that if you miss a fatigue fracture (stress fracture) of the femoral neck, the consequences can be the most severe. Without proper treatment, a marginal fracture can develop into a complete femoral neck fracture, which is much more difficult to treat and may require surgery.
In addition, a complete femoral neck fracture can heal slowly or even not at all. Another complication of a fatigue fracture of the femoral neck is osteonecrosis (aseptic or avascular necrosis of the femoral head), which may require serious operations to treat: femoral osteotomy or hip replacement.
Treatment of fatigue fractures of the pelvic and femoral bones is usually conservative, i.e. non-surgical. To relieve a sore leg, you can use crutches at first. Then, as the pain subsides, they are allowed to step on the affected leg, gradually increasing the load until the pain appears. The same tactic is used if the bone pain is not caused by a fracture, but simply by overwork; in this case, recovery occurs faster.
During the recovery period, exercises that strengthen the leg muscles, but at the same time relieve the bones from having to support the weight of the body, are useful. These exercises include, for example, swimming, water aerobics, and exercise bike classes.
Treatment of fatigue fractures of the femoral neck depends on their location. Lower fatigue fractures are compression fractures by their mechanism of occurrence; they rarely progress to a complete fracture and are therefore treated conservatively. The injured leg is unloaded, focusing on complaints. If the leg support is painful, the patient is placed on crutches for up to a month and a half; then, if the leg support no longer causes pain, the ban is lifted and physical exercises are prescribed. Increase the load should be extremely careful, focusing on the severity of pain. If long-term conservative treatment is ineffective, surgery is indicated.
Surgical treatment. Upper fatigue fractures of the femoral neck often turn into a complete fracture with displacement of bone fragments, so they are considered an indication for preventive percutaneous fixation (osteosynthesis)of the femoral head and neck. Under the control of radioscopy, three hollow screws are screwed into the head through the outer surface of the femur, parallel to each other, placing them at the corners of an imaginary isosceles triangle for maximum stability.
Osteosynthesis of the femoral neck with three screws for stress fracture
The prognosis after fatigue fractures is good, with the exception of only upper fatigue fractures of the femoral neck, which require serious surgical treatment. If the treatment of a fatigue fracture of the femoral neck is inadequate, then serious complications are possible and recovery will not always be complete. It can take up to 6 months to return to the sport (for fatigue fractures of the femoral neck, for other fractures – less). Repeated radiographs and bone scintigraphy can help determine whether the fracture has healed sufficiently to resume training. As the load on the affected leg increases, the radiography is repeated to make sure that the fracture does not progress.