Knee replacement for my mother

Hi. My mother aged 66 years old can't walk now. The doctors have recommended both knee replacement otherwise she will have deep pain in both knees. The material inside the knee has worn out and the bones touch each other creating deep pain. The cost is 8000 euros for one knee which I cannot afford from my meagre salary. The insurance do not cover this because it is an old problem and under insurance rules old problems are not covered. Please please help me financially in getting new knee for my mother so that she can walk again.