Bone Marrow Edema of the Knee

As MRIs become more commonplace, providers are finding more bone marrow edema. On a T2 weighted fat suppression MRI image, bone marrow edema will appear bright in contrast to a normally appearing dark/low fluid intensity appearing bone (1,2).

T2 Image of Bone Marrow Edema (2)

Formal naming of bone marrow edema can be confusing. Bone marrow edema has taken on multiple names and some of the more common are transient osteoporosis, spontaneous osteonecrosis, and subchondral insufficiency fracture (1).

Nomenclature of Bone Marrow Edema (8)

Radiologists have tried to classify bone marrow edema syndrome as primary or secondary (9). A primary source involves the large weight bearing joints and the cause is usually unknown (9). A secondary source is caused by acute or chronic repetitive stresses (9). Bone marrow edema has been found more commonly in older patients. This can create confusion as to the etiology of the edema because older patients have higher rates of osteoarthritis, which can be associated with edema (1).  Research has shown that articular cartilage degeneration is associated with the development of bone marrow edema (2). Bone marrow edema typically occurs in the areas where the articular cartilage is damaged (5).

There are multiple hypotheses regarding the etiology of bone marrow edema. The cause of the marrow edema can be the result of ischemic changes in the bone marrow and reactive changes to mechanical stress (4). Much attention to the etiology of the bone marrow edema has been given to the subchondral bone (3). Histologic samples of bone marrow edema show fibrotic changes, necrosis, and poor mineralization within the subchondral bone (3). In cases of spontaneous osteonecrosis, there is an increase of fluid in the bone marrow that can lead to haversian collapse (3). MRI can help aid in the diagnosis of spontaneous necrosis, as the edema typically is found around a thickened area of necrosis (6).

Trauma can also lead to the formation of bone marrow edema due to the presence of blood and interstitial fluid within the marrow (5).

Patients with bone marrow edema experience pain with weight bearing (1). Independently, bone marrow edema is a risk factor for needing a total knee arthroplasty (3).  There also is no clear association between osteopenia and osteoporosis in the development of bone marrow edema (8).

There are normal variants of marrow edema that are found in MRI studies. Haemopoietic marrow is typically found in peri-menopausal woman and will have the appearance of less intense marrow edema.

Hematopoietic marrow with less fluid intensity (5)

There is also debate as to the significance of asymptomatic bone marrow edema lesions found in runners (7).

Treatment can vary but many cases will resolve with conservative measures (4). Studies have begun looking at the role of intraosseous injections for the treatment of bone marrow edema.

Bone marrow edema is characterized by an increase in fluid intensity on a T2 fat suppressed image (3). These lesions can be painful and are a risk factor for requiring total knee arthroplasty. Future treatments including intraosseous injections may serve a role in their treatment.

By Gregory Rubin, DO
rubinsportsmed.com

References

1)      Karantanas, Apostolos H., et al. “Acute Non-Traumatic Marrow Edema Syndrome in the Knee: MRI Findings at Presentation, Correlation with Spinal DEXA and Outcome.” European Journal of Radiology, vol. 67, no. 1, July 2008, pp. 22–33. PubMed, https://doi.org/10.1016/j.ejrad.2008.01.053.

2)      Bining, H.J.S., Santos, R., Andrews, G. et al. Can T2 relaxation values and color maps be used to detect chondral damage utilizing subchondral bone marrow edema as a marker?. Skeletal Radiol 38, 459–465 (2009). https://doi-org.ezproxy.med.ucf.edu/10.1007/s00256-008-0629-y

3)      Kasik, Connor S., et al. “Short-Term Outcomes for the Biologic Treatment of Bone Marrow Edema of the Knee Using Bone Marrow Aspirate Concentrate and Injectable Demineralized Bone Matrix.” Arthroscopy, Sports Medicine, and Rehabilitation, vol. 1, no. 1, Nov. 2019, pp. e7–14. PubMed, https://doi.org/10.1016/j.asmr.2019.07.001.

4)      Ververidis, Athanasios N., et al. “Surgical Modalities for the Management of Bone Marrow Edema of the Knee Joint.” Journal of Orthopaedics, vol. 17, 2020, pp. 30–37. PubMed, https://doi.org/10.1016/j.jor.2019.08.025.

5)      Fowkes, Lucy A., and Andoni P. Toms. “Bone Marrow Oedema of the Knee.” The Knee, vol. 17, no. 1, Jan. 2010, pp. 1–6. PubMed, https://doi.org/10.1016/j.knee.2009.06.002.

6)      Beckwée, David, et al. “The Influence of Joint Loading on Bone Marrow Lesions in the Knee: A Systematic Review With Meta-Analysis.” The American Journal of Sports Medicine, vol. 43, no. 12, Dec. 2015, pp. 3093–107. PubMed, https://doi.org/10.1177/0363546514565092.

7)      Niva, Maria H., et al. “Bone Stress Injuries Causing Exercise-Induced Knee Pain.” The American Journal of Sports Medicine, vol. 34, no. 1, Jan. 2006, pp. 78–83. PubMed, https://doi.org/10.1177/0363546505278699.

8)      Patel, Sanjeev. “Primary Bone Marrow Oedema Syndromes.” Rheumatology (Oxford, England), vol. 53, no. 5, May 2014, pp. 785–92. PubMed, https://doi.org/10.1093/rheumatology/ket324.

9)      Vitali, Matteo, et al. “Bone Marrow Edema Syndrome of the Medial Femoral Condyle Treated With Extracorporeal Shock Wave Therapy: A Clinical and MRI Retrospective Comparative Study.” Archives of Physical Medicine and Rehabilitation, vol. 99, no. 5, May 2018, pp. 873–79. PubMed, https://doi.org/10.1016/j.apmr.2017.10.025.