Efek ekstrak etanol 70% rumput mutiara (Hedyotis corymbosa (L.) Lamk.) terhadap penurunan jumlah osteoklas tulang calcaneus tikus model artritis reumatoid = The effect of 70% ethanolic extract of pearl grass (Hedyotis corymbosa (L.) Lamk.) in osteoclasts reduction in calcaneus bone of male rats rheumatoid arthritis model