Background Early stage of osteophyte (OP) formations are hard to be detected by radiography, but can be detected by magnetic resonance imaging (MRI). Their subsequent developments on structural and clinical abnormalities are still unknown.
Objectives To describe the prevalence of early osteophytes (OPs) that were detected by magnetic resonance imaging (MRI) but not by X-ray in older adults and to evaluate the longitudinal associations with knee pain and structural changes.
Methods 837 participants (mean age 62 years, 50% female) were randomly selected from local community at baseline. T1- or T2-weighted fat suppressed MRI was used to assess knee OPs, cartilage volume, cartilage defects and bone marrow lesions (BMLs) at baseline and after 2.6 years. Knee pain was assessed by self-administered Western Ontario and McMaster Osteoarthritis (WOMAC) Index questionnaire at baseline and after 5 years. X-ray-detected OPs were assessed at baseline using the Osteoarthritis Research Society International atlas. OPs detected only by MRI but not by standard X-ray were defined as early OPs. OPs detected by both MRI and X-ray were defined as definite OPs.
Results The prevalence of early OPs was 75% while the prevalence of definite OPs was 10% in total knee at baseline. Compared with participants without any OPs, participants with early OPs and with definite OPs had greater cartilage volume loss and increased cartilage defects and BMLs over 2.6 years. Presence of early medial tibiofemoral OPs predicted decreases in total knee pain over 5 years, while definite OPs predicted increases in total knee pain, after adjustment for relevant covariates.
Conclusions Although early OPs are associated with knee abnormal structural changes, they predict decreases in knee pain over time suggesting an adaptive response.
Centers for Disease C, Prevention. Public health and aging: projected prevalence of self-reported arthritis or chronic joint symptoms among persons aged >65 years–United States, 2005–2030. MMWR Morb Mortal Wkly Rep 2003; 52: 489–491.
Acknowledgements The authors thank the participants who made this study possible, and acknowledge the role of the staff and volunteers in collecting the data, particularly research nurses Boon C and Boon P. Warren R assessed MRIs and Dr Srikanth V and Dr Cooley H assessed radiographs.
Disclosure of Interest None declared