Association between bisphosphonate use and risk of undergoing knee replacement in patients with osteoarthritis

Osteoarthritis (OA) is the most common joint disorder and the major cause of chronic musculoskeletal pain and mobility disability in elderly populations worldwide.1 Currently there is no effective pharmacological treatment for OA, necessitating joint replacement to reduce joint pain and improve physical functions at advanced stages of the disease.2 It has been reported that abnormal subchondral bone resorption and bone loss play an important role in both OA initiation and progression.3–5 Therefore, antiresorptive drugs are suggested to be potential OA therapies.6 We read with deep interest a recent article published in this journal by Neogi et al , who found that in elderly women with newly diagnosed knee OA, those who use bisphosphonates had lower risk of knee replacement than non-users, and suggested that treatment with bisphosphonates has a potential beneficial effect on knee OA.7 We really appreciate the great work performed by the authors; nevertheless, some worthwhile issues need to be further explored.First, the definition of knee OA at baseline is not clearly described in the study. Nowadays there is no consensus on the classification criteria of knee OA despite extensive epidemiological and clinical studies. The two criteria most frequently used are the American College of Rheumatology (ACR) classification criteria8 and the Kellgren and Lawrence (K-L) system.9 The ACR classification criteria depend on clinical (such as pain, aching or …