In this sentence, Jessie injured the same ankle that was hurt before, I know that the relative clause is "that was hurt before" and is the adjective clause modifying the direct object of injured, the ankle. Then why is the noun function of the relative clause is the subject? All help is appreciated

Which sentence in this excerpt from leo tolstoy’s the death of ivan ilyich shows the human tendency to contemplate one’s past life? "but if that is so," he said to himself, "and i am leaving this life with the consciousness that i have lost all that was given me and it is impossible to rectify it—what then? " he lay on his back and began to pass his life in review in quite a new way. in the morning when he saw first his footman, then his wife, then his daughter, and then the doctor, their every word and movement confirmed to him the awful truth that had been revealed to him during the night. in them he saw himself—all that for which he had lived—and saw clearly that it was not real at all, but a terrible and huge deception which had hidden both life and death. this consciousness intensified his physical suffering tenfold. he groaned and tossed about, and pulled at his clothing which choked and stifled him. and he hated them on that account. he was given a large dose of opium and became unconscious, but at noon his sufferings began again. he drove everybody away and tossed from side to side. his wife came to him and said: "jean, my dear, do this for me. it can't do any harm and often . healthy people often do it." he opened his eyes wide. "what? take communion? why? it's unnecessary! " she began to cry. "yes, do, my dear. i'll send for our priest. he is such a nice man." "all right. very well," he muttered. when the priest came and heard his confession, ivan ilyich was softened and seemed to feel a relief from his doubts and consequently from his sufferings, and for a moment there came a ray of hope. he again began to think of the vermiform appendix and the possibility of correcting it. he received the sacrament with tears in his eyes.