Bone edema is the term used by doctors (radiologists) to describe swelling within bone. Bone swelling is typically identified on MRI and is the result of either a direct injury to bone or load bearing that is greater than what can be sustained by the bone (stress injuries). Bone edema can also be found secondary to an inflammatory injury of bone. Inflammatory injuries include various forms of infection or arthritis.
How does bone edema heal? The first issue to consider when discussing bone edema is the primary cause for the bone edema. For instance, if bone edema is secondary to an infection, the infection has to be treated for the bone edema to heal. Or if the bone edema is due to a stress injury, the mechanical stress needs to be eliminated.
Once the primary cause for bone edema is identified and eliminated, then we can look at the dynamics of bone healing in response to bone edema. One classic tool that helps to determine the rate of bone healing is a classification scheme. In many types of bone injuries/fractures we use classifications schemes to define characteristics of the injury such as depth of the injury, overall size of the injury, etc. Classification schemes help to guide us with answers to our patient’s question such as how long will this take to heal. But when we discuss bone edema, we have a problem. To date, we’ve had a difficult time defining bone edema in a classification scheme. And without a classification scheme, we then have a difficult time answering that question…how long will this bone edema injury take to heal.
In my practice (foot and ankle care), I’ve tended to find that when we discover bone edema on an MRI, the injury may take as long if not longer than most fractures to heal. For instance, a common foot problem that we’ll see is a metatarsal stress fracture. If the stress fracture doesn’t show on plain x-ray, we’ll send our patient for an MRI. And if that MRI comes back with a diagnosis of bone edema within the metatarsal, we then have an idea about overall time that it’ll take for bone healing. What’s the typical duration of time for a metatarsal stress fracture? I’d tell most folks 8-12 weeks. But with bone edema in the metatarsal, it may take as long if not longer than a traditional fracture.
Additional variables that influence the duration of healing of bone edema include the size of the bone that is injured, the type of bone that is injured, the depth of the injury and the overall size.
Unfortunately, until we can develop a classification scheme for defining the healing rate of bone edema, each doc just draws from his or her experince with previous patients and similar injuries. So if your doctor recommends an MRI and your MRI comes back with a diagnosis of bone edema, be patient with your doc. She/he will try to guide you with answers, but defining how long bone edema will take to heal can be a challenge.
Jeffrey A. Oster, DPM