Knee replacement should be the last resort. You should try ayurveda before going for that. Ayurveda will prevent arthritis from further deterioration and will help in pain management.

If the cartilage between two major bones of a leg is totally damaged, then there is no option other than surgery; provided general physical condition permits. Ayurveda has part of panchakarma to relieve arthritis pain & it need to be periodically done. This option is applicable after seeing the X-ray/ MRI reports

Knee surgery is suggested for osteoarthritis. We have to know the history and degree of degeneration to determine whether surgery is advisable. Coming to ayurveda we have various treatments for osteoarthritis like Janu vasti( oil retention in knee), abhyangam(ayurveda medicated massage), kizhi( hot fomentation).nadi diagnosis and proper consultation are necessary.

आयुर्वेद में चिकित्सा हो सकती है, रोगी रोगानुसार आवश्यकता अनुसार लाभ  मिलता है

Ayurvedic treatment can many times avoid surgery,But for treatment in such case need detail history .Your mother also need panchkarma with treatment so please visit ayurvedic doctor.www.junankarayurveda.com

I need to know what happened to knee in detail . But yes ayurvedic treatment & therapy will surely help your mother to cure . Considering your mother age knee replacement have max 5 to10 yrs benefit. According to me you should start ayurvedic treatment as well therapies like janu basti or janu dhara for knee along with massage & steam , most importantly shastishalik Pind swedan.