Perbedaan Skor Nyeri, Fleksibilitas, Kemampuan Fungsional, dan Ketebalan Ligamen Kolateral Medial pada Pasien Osteoartritis Lutut Sebelum dan Sesudah Mendapatkan Shock Wave Therapy = Differences in Pain Score, Flexibility, Functional Performance, and Medial Collateral Ligament Size in Knee Osteoarthritis Patient Before and After Shock Wave Therapy.