Published on: 29-Jun-2018
Many people are surprised to learn that bone has a blood supply. It’s every bit a living tissue as skin, your brain, or your heart. And like any of those other tissues with a blood supply, a bone can be bruised.
Lots of people are familiar with a bruise on the skin. If you bump the outside of the skin hard enough it will cause tiny blood vessels in the skin to break, leading to some bleeding in the skin. This causes the common black/blue/green discoloration. If you hit a bit harder the force can be transmitted deeper, to the underlying muscle. And if you hit harder still that force can go straight to the bone.
A bone bruise is an injury to the interior of the bone (the bone marrow) with enough force to disrupt the internal blood supply but not enough force to crack the outside of the bone. A bone bruise is an injury that almost broke the bone but came up just short. There are several sports scenarios that can cause bone bruises. Common ones I see are direct impact injuries such as a fall onto a hard surface, or a bone bruise to the arm in a batter hit by a pitch. We’ll see a fair number from player to player contact, and there’s also a bone bruise pattern we see on an MRI of a knee with an ACL tear.
One of the key features of a bone bruise is that it can be extremely painful immediately after the injury. Severe pain after impact typically makes an orthopedic surgeon concerned for a fracture, and if the initial x-ray shows no broken bone a common next thought would be for a bone bruise. A bone bruise is diagnosed by MRI scan, and x-rays are typically normal.
The good news about a bone bruise is that the same system that causes the bruise- the internal blood supply- is also the system that creates the environment for healing. Like the bruise in the skin, the bone bruise will typically go on to heal. What’s usually required is limiting the impact loading that caused the problem. In the upper extremity the treatment may be and arm sling or brace followed by light activity until healing. In the lower extremity crutches, a brace, or a boot may be needed.
The tough part about a bone bruise is that they can be very painful, especially in the initial healing phase. The other key consideration for the athlete is that return to play can be highly variable, taking from a couple of weeks to several months.
There are several interesting variables about bone bruises. First, the long term implications of a bone bruise are unknown. We believe that the vast majority of bone bruises will go on to heal in the near term but there isn’t yet enough data to know whether there are any long term implications. Second, the extent of the bruise on an MRI is not necessarily correlated with pain. We see severe pain with fairly minimal bone bruising, and conversely we see some severe bruises on an MRI in people with only a small amount of pain.
Because of the lack of clear correlation between bruising on the MRI, pain, and function, we will usually not repeat an MRI to assess healing but instead rely on how the injured athlete feels and how they are functioning. When pain is resolved and the function is restored we’ll usually allow the athlete to return to play.