Osteoarthritis and Cartilage. 2012; 20(12):1514-1518.
OBJECTIVES: Knee osteoarthritis (OA) is thought to be a slowly evolving disease with
glacial changes in cartilage morphology necessitating trials of potential treatments
lasting 1 -2 years with evidence that over 6 months change in cartilage is not detectable.
In contrast to cartilage, bone has the capacity to adapt rapidly, such as after fracture.
we tested whether bone marrow lesions (BMLs) change in volume in 6 and 12 weeks, suggesting
they may provide evidence of short term fluctuations of joint damage. METHODS: In
62 patients with patellofemoral knee OA, ( mean age 55. 7years, 59.7% women, mean
BMI 31.0), we obtained baseline, 6 and 12 week knee MRIs with contrast enhancement.
Of those with BMLs at baseline, we assessed BML volumeon the axial proton density
fat saturated images and postcontrast sagittal T1 weighted fat saturated images. We
manually segmented BML volumes, testing repeatability of BML volumes in knees remeasured.
Using the standard deviation of the difference between repeated measurements to calculate
Bland Altman limits of agreement, we determined how much BML volume change represented
a change greater than due to chance RESULTS: Fifty two patients had BMLs at baseline.
Test-retest reliability for BML volume was high (ICC 0.89, 95% CI 0.80 to 0.97). All
knees showed at least some change in BML volume by 6 and 12 weeks. On the axial view
at 6 weeks, 20/49 (40.8%) knees showed BML volume changes greater than the limits
of agreement with similar results at 12 weeks. BML changes were evenly divided among
knees with enlarging and shrinking BMLs. 63.3% of the knees had more than 50% change
in BML volume at either 6 or 12 weeks on the axial view and 48.7% on the sagittal
view. CONCLUSIONS: Knee BML volumes change in several weeks in many persons with knee
OA. To the extent that they could be regarded as treatment targets, trials testing
BML effects could avoid the usual prolonged structure modification trials.