Increased serum and synovial levels of midkine are associated with radiological progression in primary knee osteoarthritis patients

Abstract

Abstract Background Midkine is a heparin-binding growth factor that is believed to have functional antagonism, although it helps in tissue repair, it can also enhance inflammatory reactions resulting in more tissue injury. Aim of the work This study aimed to determine serum and synovial fluid (SF) levels of midkine in patients with primary knee osteoarthritis (KOA) and to correlate these levels with patients’ clinical and functional parameters as well as radiological progression of KOA. Patients and methods Midkine was measured in the serum and 23 SF samples from 52KOA patients as well as in the serum from 20 healthy controls. In the patients, The Western Ontario McMaster scale (WOMAC) was recorded to assess functional status. Graded plain radiographs using Thomas score, and musculoskeletal ultrasound examination (MSUS) of both knees were performed at baseline and after 2\u202fyears to assess radiological progression. Results The patients mean age was 51.5\u202f±\u202f10.6\u202fyears and disease duration was 5.4\u202f±\u202f4.7\u202fyears. Serum levels were significantly increased in KOA patients (80.8\u202f±\u202f31.8\u202fpg/mL) compared to the controls (65.6\u202f±\u202f14.8\u202fpg/mL). Patients with elevated serum and SF midkine had twofold increased risk of radiological progression with MSUS (RR2.4 and 2.6 respectively). However, there was no increased risk of radiological progression detected with plain radiography. Conclusion Osteoarthritis patients have significantly elevated serum and synovial levels of midkine that were correlated with functional status assessed with WOMAC index and obviously associated with radiological progression on MSUS suggesting that it could be a useful marker to reflect OA severity and implies a possible role in the disease pathogenesis.