Bone bruising was a phenomenon that was not observed prior to magnetic resonance imaging, according to the International Society of Arthroscopy, Knee Surgery & Orthopaedic Sports Medicine. Bone marrow edema and bone bruising appear the same on MRI. If the patient has a history of injury to the bone, it is referred to as bone brusing. In diseases such as arthritis and sickle cell disease, bone marrow edema correlates with bone pain.
Bone marrow has three components: the bony portion, a fatty portion, and a portion that makes blood cells. The composition of bone marrow changes to have less blood formation with age. There is more fatty marrow. The last area of bone to change is near the ends of bone and in the spine. In marathon runners, high altitude residents, and menstruating women, islands of blood forming marrow can be seen on MRI, according to the American Roentgen Ray Society.
Bone marrow edema or bone bruises are areas of increased fluid. This can occur from small fractures of the bone, blood, or increased fluid. Bone edema on MRI helps to diagnose several conditions.
When the bones are subject to repetitive force, they may develop a stress fracture from loading or muscle pull. New military recruits who are unaccustomed to marching, distance runners and ballet dancers are at risk for stress fractures. These fractures do not initially show-up on X-rays. Fractures of the hip may require surgery. Early diagnosis of stress fractures is done with MRI. There is bone edema and sometimes a visible fracture line, according to the Clinical Sports Medicine website.
Bone bruises have helped to understand the mechanics of Anterior Cruciate Ligament tears in the knee. ISAKSOSM cites studies showing that bone edema is dependent on time after injury with up to 80 percent of patients with ACL tears having bone edema on MRI. The bone bruises are typically located on the lateral portion of the knee. The presence of bone edema is more likely with a complete ACL tear than a partial tear. ISAKSOSM reports that some researchers are investigating if bone bruising is correlated with development of arthritis, since the cartilage over bone bruises is affected in some studies, but not all studies, says the International Society of Arthroscopy.
Bone marrow edema is more common in arthritic patients who are experiencing pain. Both bone pain and bone edema develop after activity in arthritics. "The Journal of Rheumatology" reports that a multi-center rating system of MRI arthritic findings found bone edema, synovitis, and erosions were consistently rated by reviewers. ISAKSOSM estimates 40 percent of arthritics with bone edema have worsening of joint surfaces within year.
Cancer and Infection
Infection and cancer produce bone edema. The inflammatory infection cells and metastatic tumor cells produce high water content bone which is seen as edema on MRI. Radiation treatment initially produces bone edema. Changes in the bone marrow from medication used to stimulate the marrow to produce more blood cells may be seen on MRI. Increased blood cell production due to sickle cell blood diseases and other anemias also cause bone edema.
The increased use of MRI has led to a new diagnosis; transient bone marrow edema syndrome, BMES. This was first seen in the hip. It was not correlated with avascular necrosis which is death of the bone. Another disease, transient osteoporosis, begins with hip pain. Loss of bone mass is then seen on X-ray. BMES doesn’t have the initial pain. ISAKSOSM theorizes these three syndromes may be related.
Bone edema is actively being studied. It is not clear why some people have persistent bone edema. ISAKSOSM reports that most bone bruises resolve four to 12 months after the injury but 10 to 15 percent of patients have bone edema two years after injury. The long-term effects and meaning of bone edema are still being discovered.