Your surgeon will base a diagnosis of a subchondral bone defect on your clinical history, physical exam and MRI findings.

A subchondral bone defect, often referred to as a Bone Marrow Lesion, or BML, is a term for a finding on an MRI that represents an abnormal area or defect inside the bone.

MRI of Bone Marrow Lesion in the knee.
ankle MRI
MRI of Bone Marrow Lesion in the ankle.

What is a Bone Marrow Lesion (BML)?

Bone marrow lesions (sometimes called Bone Marrow Edema) are small defects typically found in subchondral bone, the region below the cortical bone near a joint. They can only be seen on certain MRI sequences, appearing as a hazy white area against the background of darker bone.

Pathologists have shown that BML represent a healing response surrounding small defects in the subchondral bone, such as micro trabecular fractures.1

Generic Joint

This type of defect can be found throughout the extremities and pelvis. They can be found near any joint that sees weight-bearing or repetitive motion stress.

Tibia Plateau BML (knee)
Tibia Plateau BML (knee)
Talar Dome BML (ankle)
Talar Dome BML (ankle)

What Causes a BML?2

In some cases, BML defects are a result of a bone injury that doesn't heal properly. In other cases, BML may be a stress reaction that forms from overuse or poor joint mechanics. Other factors that correlate to chronic BML include:

  • Obesity and poor diet are thought to increase the likelihood of developing BML
  • BML are more commonly found in middle-aged patients than in younger patients
  • Patients with poor joint alignment are more likely to develop BML
  • Adults who quickly increase activity may develop BML


  • 1 Eriksen EF, Ringe JD. Bone marrow lesions: a universal bone response to injury? Rheumatol Int. 2012;32(3):575-584
  • 2 Roemer FW, Neogi T, Nevitt MC, et al. Subchondral bone marrow lesions are highly associated with, and predict subchondral bone attrition longitudinally: the MOST study. Osteoarthritis Cartilage. 2010;18(1):47-53.

Important Information: As with every surgical procedure, there are risks and potential complications. Individual results may vary. Success depends on factors such as age, weight and activity level.