A bone bruise is a traumatic injury to a bone that is less severe than a bone fracture, causing blood and fluid to build up near the injured bone.
Bones have a cortex, or outer shell, made of interconnected fibers. Calcium fills the spaces between the fibers.If enough of those fibers break during a trauma, a bone fracture will result, but a bone bruise occurs when a smaller portion of the fibers break. This can result in pain, swelling and change in color of the affected area.
Typical recovery time
Bone bruises do not show up on X-rays and must be diagnosed with MRIs. Depending on depth and severity, they may heal in as little as a few weeks or require as long as six months.
On Aug. 12, 2017, Nationals outfielder Bryce Harper suffered a bone bruise in his left knee when he slipped on a wet first base. He didn't begin light jogging until a month later, on Sept. 13. In June of the same year, Marlins first baseman Justin Bour missed 10 days with a bone bruise in his left ankle.