老人因关节炎走路时腿直挺挺的，无法弯曲膝盖。

The old man walks ___stiff-legged due to arthritis, unable to bend his knees.

尽管团队提出了更好的方案，他还是固执己见地坚持自己的计划。

Despite better suggestions from the team, he remained ___stiff-legged in sticking to his own plan.