Pittsburgh placed Arnold (calf) on injured reserve Thursday, Alan Saunders of SteelersNow.com reports.
Arnold hurt his calf during practice Wednesday and has landed on IR one day later. The 26-year-old had been competing for a roster spot after logging 18 tackles (12 solo) and a forced fumble over eight regular-season contests with Houston last season. Arnold's placement on IR means he'll be required to miss the entire 2024 campaign unless he and the Steelers reach an injury settlement.