Is it permissible to pray kneeling due to bowed legs and the inability to stand naturally?

Standing in obligatory prayers is a pillar for one who is able to do so, based on the Almighty's saying: "And stand before Allah, devoutly obedient." (Quran 2:238). Whoever is unable to stand should pray sitting, based on the hadith of Imran ibn Husayn: "Pray standing; if you are unable, then sitting; and if you are unable, then on your side." Some scholars are of the opinion that whoever is able to stand on their knees must do so.