Dr Veena Aggarwal

Several risk factors such as age, body weight, injury to the joint or trauma due to frequent squatting etc. affect pain in patients with knee osteoarthritis. However, as the disease advances, the number of major risk factors decline and only few remain significant as shown in a new study published in the journal Arthritis Care & Research.1

In this study, researchers reviewed data of 4446 patients, mean age 61 years, with osteoarthritis (OA) of the knee from the prospective, multicenter Osteoarthritis Initiative (OAI) conducted in the United States. Based on the scores on the numerical rating scale (NRS), the severity of pain in the preceding 30 days was categorized as no pain (0 score), mild pain (0 to ≤3) and moderate/severe pain (>3). Knee OA severity was stratified into 4 categories according to the Kellgren and Lawrence (K/L) system. Through this study, the researchers aimed to examine if risk factors related to pain differed at different stages of knee OA. The mean BMI of the participants was 28.5 kg/m2 and nearly 32% gave a history of knee injury.

A total of 1138 had mild pain (25.6%) and 1734 had moderate/severe pain (39.0%), while 1574 patients did not have pain (35.4%). Among patients in the premorbid OA stage, those who had a history of knee injury, diabetes, depression or were using nonsteroidal anti-inflammatory drugs (NSAIDs) reported more severe pain. Participants who had valgus malaligned knees (knock knees) also reported more severe pain than patients who had normal alignment. On the other hand, older patients and those with stronger quadriceps muscles had milder pain. Patients with higher KL grade (4) had higher probability of experiencing severe pain compared to those with lower KL grades (0/1, 2 or 3). “Only age and quadriceps muscle force remained significant in end-stage disease”, according to the authors. Therefore, management of pain due to osteoarthritis should take into consideration the radiological stage of the disease.

Dr Veena Aggarwal is Consultant Womens’ Health, CMD and Editor-in-Chief, IJCP Group & Medtalks Trustee, Dr KK’s Heart Care Foundation of India.