Many people experience pain in their knees and subsequently visit a physician to get a diagnosis of the problem. At a certain age (above 50) with additional complaints such as joint stiffness and functional disabilities the physician might arrive at a diagnosis of osteoarthritis; a progressive joint disease. An x-ray can confirm this diagnosis.
Pain is one of the most common clinical features of osteoarthritis and x-rays can show the abnormalities of structures which occur with this disease. Severity of osteoarthritis can be graded into 4 grades (0=no osteoarthritis – 3=severe osteoarthritis) and a physician may base their diagnosis of knee osteoarthritis on anamnesis/history taking, however, the x-ray of the knees of this patient might show no abnormalities in the knee structure. Moreover, in epidemiological research the discordance between having knee pain and osteoarthritis defined on x-rays is a well known fact (Bedson et al. 2008). This might particularly apply to less severe osteoarthritis but there are still people whose x-rays show severe osteoarthritis but who experience no knee pain at all. We wanted to identify factors (personal factors such as gender, age, BMI and education, but also the presence of other diseases and other disease symptoms of osteoarthritis) that could be related with knee pain and we especially wanted to know if there were different factors that were related to the different severity of osteoarthritis of the knee.
We looked at the x-rays of the knees of more than 5,000 participants of the Rotterdam Study (Hofman et al. 2012) and scored them for features of osteoarthritis to define which knee could be diagnosed with knee osteoarthritis and to what degree of severity. In an extensive interview several factors were documented. As expected, an increasing percentage of participants reported knee pain when the severity of osteoarthritis seen on x-rays increased, but still 25% of the participants with the most severe grades of osteoarthritis did not report pain in their knees.
We found that being a female, having widespread pain, reporting general health complaints, having parents or siblings with osteoarthritis, and having morning stiffness are factors that are associated with knee pain. However, these factors are not specific for the severity of osteoarthritis. None of the factors we investigated were specific for more severe knee osteoarthritis or less severe knee osteoarthritis, however, people with knee pain and no structural abnormalities might have a differential diagnosis of hip osteoarthritis or feeling depressed, which both need specific subsequent management.
Dieuwke Schiphof is post doctoral researcher at the department of General Practice of the Erasmus MC in Rotterdam, Netherlands. She obtained her PhD in 2012 on the identification of knee osteoarthritis, especially classification, early recognition and imaging. Dieuwke’s post doctoral research is an extension of her PhD; she is responsible for all data-procedures, data collection and analyses of the follow-up measurements of the women who participated in a substudy of the Rotterdam Study to identify preclinical knee osteoarthritis. In addition, she is now also active in the field of musculoskeletal pain, and chronic pain in general practice.
Link to Dieuwke’s published research here. For pdf’s mail her: email@example.com.
Schiphof D, Kerkhof HJ, Damen J, de Klerk BM, Hofman A, Koes BW, van Meurs JB, & Bierma-Zeinstra SM (2013). Factors for pain in patients with different grades of knee osteoarthritis. Arthritis care & research, 65 (5), 695-702 PMID: 23203619
Bedson J, & Croft PR (2008). The discordance between clinical and radiographic knee osteoarthritis: a systematic search and summary of the literature. BMC musculoskeletal disorders, 9 PMID: 18764949
Hofman A, van Duijn CM, Franco OH, Ikram MA, Janssen HL, Klaver CC, Kuipers EJ, Nijsten TE, Stricker BH, Tiemeier H, Uitterlinden AG, Vernooij MW, & Witteman JC (2011). The Rotterdam Study: 2012 objectives and design update. Eur J Epidemiol, 26 (8), 657-86 PMID: 21877163