Evaluating the “patella-friendly” concept in total knee arthroplasty: a minimum 15-year follow-up outcome study comparing constant radius, multiradius cruciate-retaining, and nonanatomical cruciate-retaining implants - Karachalios, T; Komnos, G; Hantes, M; Varitimidis, S (J Arthroplasty, 2021)