I say, and with God's success: It is permissible to wipe over the splint of one leg while washing the other; because wiping over the splint is originally allowed, unlike wiping over the socks, where washing and wiping cannot be combined. Refer to: 'Umdah al-Ri'ayah 1: 119, Sharh al-Wiqayah p. 120, Al-Hadiyyah al-'Alaiyyah pp. 42-43, and Nihayat al-Mirad p. 400, and God knows best.