Background Although osteoarthritis (OA) is predominantly considered as a disease of cartilage, articular cartilage is an aneural tissue, and there is a consensus that the association between knee radiographic OA and knee pain is modest.
Objectives To investigate the prevalence of asymptomatic subjects with advanced knee OA, we examined databases obtained from 2 Korean community residents.
Methods Subjects included were from Hallym Aging Study (HAS) or from the Korean National Health and Nutrition Examination Survey (KNHANES, year 2010–2012). Participants in each study were asked knee-specific questions regarding the presence of knee pain. Radiographic evaluations consisted of weight-bearing anteroposterior, weight-bearing semi-flexed knee radiographs. For HAS cohort, MRI of the knee was available. Each knee was evaluated for the presence of osteophytes, joint space narrowing, subchondral sclerosis, and cysts, and was graded for overall evidence of radiographic OA using the K-L grade. Advanced knee OA was defined as K-L grade 4 (large osteophytes, severe joint space narrowing, and/or bony sclerosis). Clinical factors associated with the presence of knee pain were evaluated with multivariate logistic regression analysis.
Results Included were 504 subjects from HAS and 8679 from KNHANES. Advanced knee OA was identified in 47 (9.3%) and 685 (7.8%) in HAS and KNHANES, respectively. The mean age of the study subjects were 72.5 years and 16.5% were male. Two hundred twenty five subjects (44.3%) did not report any pain despite having K-L grade 4 OA. Female, non-smoker, the presence of osteoporosis, and lower education were significantly associated with knee pain. After multivariate association, female and osteoporosis was significantly associated with the presence of knee pain. Advanced OA subjects without knee pain did not differ from non-OA subjects in the general physical health measured with the short-form (SF-12), except for the physical functioning. Regardless of the presence of pain, MRI finding such as summary cartilage score, bone marrow lesion score, the presence of synovitis and effusion was similar in advanced OA subjects.
Conclusions Our community study showed that a significant number of subjects with K-L grade 4 OA was asymptomatic. The guidance of therapeutic decision merely based on imaging study as well as treatment option focusing solely on cartilage engineering should be viewed with caution.
Disclosure of Interest None declared