The purpose of this study was to determine if a correlation exists between magnetic resonance imaging (MRI) findings of bone marrow edema (BME) in osteoarthrosis (OA) of the knee joint and need for total knee arthroplasty (TKA) within a follow-up period of 3 years.
The entire database of knee MR studies over a 3-year period was used to select individuals with knee OA. A chart review was conducted to identify and include only those who had a 3-year follow-up appointment from the time of the initial MR study. There were 25 patients in the OA-only group (four men and 21 women; age range, 28-75; average age, 49.3 years). The OA and BME group had 48 patients (23 men and 25 women; average age, 55.5 years). The MRs were reviewed and interpreted by a musculoskeletal radiologist and were classified into one of four patterns of BME: none, focal, global, or cystic pattern. Meniscal tear and degree of cartilage loss were also assessed.
Subjects who had BME of any pattern type were 8.95 times as likely to progress rapidly to a TKA when compared to subjects with no BME (p = 0.016). Subjects with a global pattern of BME were 5.45 times as likely to have a TKA compared to subjects with focal, cyst, or no BME (p < 0.05). Subjects with a global edema pattern were 13.04 times as likely to have a TKA than subjects with no marrow edema in the knee (p < 0.01). There was no correlation of TKA with meniscal tear or cartilage loss. The group of subjects who had a TKA were 12.6 years older than those who did not have a TKA (p < 0.001). However, the BME results were still significant after accounting for the age difference.
Our classification of patterns into global, focal, cystic, and absence of BME is an attempt to further define edema in osteoarthrosis and how it relates to clinical progression. Patients with BME and OA have an increased risk of TKA as opposed to OA and no marrow edema. The BME pattern with the worst prognosis for the knee is the global pattern.