Background Bone marrow lesions (BMLs) are detected using magnetic resonance imaging (MRI) and defined as non-cystic ill-defined subchondral areas of high signal intensity. BMLs are now considered as one of the key pathologic features in knee osteoarthritis (OA)1,2. However there has been no research-examining hip BMLs and their relation to pain and cartilage.
Objectives The aim of this study was to investigate the cross-sectional relationship between hip BMLs, cartilage signal change and pain.
Methods Four hundred and forty three randomly selected older adults (mean age 63 yrs) were included in this study. They had a right hip MRI using standardized protocols (both T1 and T2-weighted). Acetabular and femoral hip BML presence was defined as being adjacent to the cartilage bone interface. Bml size (cm2) was assessed manually by drawing contours around the outer edges of the lesion on the sagittal T2-weighted MR images. High cartilage signal intensity was recorded (yes or no). Hip pain and knee pain were assessed using the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index pain score.
Results Sixty-nine participants (15.6%) had either a femoral or acetabular BML. Acetabular BML presence was not associated with hip or knee pain. Knee pain (but not hip pain) was more common in people with a femoral BML (83% v 16%,p=0.03). On average, acetabular BML size (0.66 cm2) was larger than femoral BML size (0.11cm2). Acetabular BML size was significantly associated with hip pain (p=0.02) while femoral BML size was significantly associated with knee pain (p<0.001) but not vice versa. This was especially notable in males (Figure 1). Hip BMLs were strongly associated with increased cartilage signal in the hip (58% v 2%,p<0.001) but increased cartilage signal was not associated with hip or knee pain.
Conclusions Hip BMLs are common and have site-specific associations with pain. Further, hip BMLs are associated with high cartilage signal change, which is asymptomatic but implies BMLs have a deleterious effect on overall joint health. Thus, hip BMLs may also be a key player in hip osteoarthritis.
Zhai G et al. Arthritis care and Research 55(2): 264-271; 2006
Dawn Dore et al. Arthritis Research and Therapy 12(6): R222, 2010
Disclosure of Interest None Declared