Hello, your father has grade 3 (KL) Osteoarthritis of right knee joint. Although it's difficult to suggest any treatment unless we know his age,clinical findings and if this xray has been taken in standing position. The pain can subside by physiotherapy, medicines and activity modification. However, long term painkillers would harm other organs.
Next Steps
He needs consideration for further management after seeing standing x-rays and clinical signs
Health Tips
Avoid sitting on floor or any deep knee bending activities.