Bone Edema - how long does it take to heal?
Bone edema describes 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 such as infection or arthritis.
How does bone edema heal? The first issue to consider in healing bone edema is the primary cause of 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 tool that helps to determine the rate of bone healing is a classification scheme. In many types of bone fractures, we use classifications schemes to define characteristics of the injury such as depth of the injury, overall size of the injury, etc. But when we discuss bone edema, we have a problem - to date, we no 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 as a hospital-based podiatrist I’ve tended to find that when we discover bone edema on an MRI, and we've excluded the diagnosis of infection, the injury to the bone 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 (precursor to a stress fracture), we then have an idea about overall time that it’ll take for bone healing. What’s the typical healing 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.
Some of the most challenging issues related to bone edema involve injuries to joints. The two images here show bone edema on MRI. This bone edema in the ankle (left) and subtalar joint (right), are due to injuries that occured when localized stress was applied to the joint, passing through the cartilage. These injuries are often called transchondral or osteochondral fractures. In a transchondral fracture, the cartilage stays intact but the underlying bone is injured resulting in bone edema.
Treatment of osteochondral injuries that result in bone edema can include:
Prior to any surgical intervention in bone edema, I'll let a joint rest for 8 weeks to see how the bone responds. Depending upon the location of the injury, rest may include partial weight-bearing or complete non-weight bearing.
Microfracture is a technique used to reactivate bone healing. Microfacture is a technique where a small thin wire is used to drill the edema site. The intent of drilling the site is to stimulate bone healing. And lastly, subchondroplasty is a technique where the patient's bone marrow or other substance is injected into the area of bone edema. Here's a link to the Zimmer website with additional information on the subchondroplasty technique.
Unfortunately, until we can develop a classification scheme for defining the healing rate of bone edema, each doc just draws from his or her experience 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