1. 1) Andrianakos A, Trontzas P, Christoyannis F, Dantis P, Voudouris C, Georgountzos A, Kaziolas G, Vafiadou E, Pantelidou K, Karamitsos D, Kontelis L, Krachtis P, Nikolia Z, Kaskani E, Tavaniotou E, Antoniades C, Karanikolas G and Kontoyanni A: Prevalence of rheumatic diseases in Greece: a crosssectional population based epidemiological study. The ESORDIG Study. J Rheumatol. 2003, 30: 1589–1601.
2. 2) Felson DT, Lawrence RC, Hochberg MC, McAlindon T, Dieppe PA, Minor MA, Blair SN, Berman BM, Fries JF, Weinberger M, Lorig KR, Jacobs JJ and Goldberg V: Osteoarthritis: new insights. Part 2: treatment approaches. Ann Intern Med. 2000, 133: 726–737.
3. 3) Naredo E, Cabero F, Palop MJ, Collado P, Cruz A and Crespo M: Ultrasonographic findings in knee osteoarthritis: a comparative study with clinical and radiographic assessment. Osteoarthritis Cartilage. 2005, 13: 568–574.
4. 4) Brandt KD, Heilman DK, Slemenda C, Katz BP, Mazzuca S, Braunstein EM and Byrd D: A comparison of lower extremity muscle strength, obesity, and depression scores in elderly subjects with knee pain with and without radiographic evidence of knee osteoarthritis. J Rheumatol. 2000, 27: 1937– 1946.
5. 5) Steultjens MP, Dekker J, van Baar ME, Oostendorp RA and Bijlsma JW: Range of joint motion and disability in patients with osteoarthritis of the knee or hip. Rheumatology (Oxford). 2000, 39: 955–961.