Hello Prakash ji,
Pain after plastic surgery, especially in elderly patients, can be due to various factors such as nerve sensitivity, healing issues, or underlying conditions like poor circulation or arthritis. Since your father is 90 years old and having difficulty sleeping due to pain, it is important to consult his doctor for a proper evaluation. They may recommend pain management strategies, physiotherapy, or medication adjustments. Ensure he stays comfortable and keeps his leg elevated if advised by the doctor. Let us know if you need further guidance!