The following symptoms could indicate the requirement for a total knee replacement surgery:

• Severe pain in the knee joint
• Severe stiffness in the knee joint 
• Knee pain not relieved on sleeping or resting
• Knee joint inflammation
• Knee joint swelling 
• Deformity in the knee joint, such as bowing in or out of the knee
• Other treatment options fail to treat knee pain and stiffness 

The following diagnostic tests may be done before a total knee replacement surgery:

1. Physical examination: The doctor checks the knee strength, stability, motion, and leg alignment. The symptoms of the patient are noted.
2. X-rays of the knee joint: This test helps the doctor check the image of the knee joint and see if any deformity or damage is present.
3. CT scans and MRI scans: Imaging tests such as MRI scans and CT scans help in obtaining clear images of the knee joint and checking the condition of the bone and soft tissues present in the knee joint.
4. Blood tests: Certain underlying medical conditions can be diagnosed with the help of these tests.
5. Urine tests: Underlying urinary infections can be checked using these tests.
6. Electrocardiogram (ECG): The electrical activity of the heart can be recorded by an ECG. 

Total knee replacement surgery is generally performed under general anesthesia (the patient is put to sleep during the procedure).
The procedure may be performed in the following different ways:

1. Open surgery:

• An incision or cut is made by the surgeon at the knee region.
• The damaged cartilage surfaces present at the end of the femur and tibia are removed along with a small part of the underlying bone.
• The removed cartilage and bone are now replaced using metal components that recreate the joint surface.
• These metal parts can either be cemented or press-fitted into the bone.
• The undersurface of the patella (kneecap) is now cut and resurfaced with a plastic button. However, in some cases, the doctor may not resurface the patella.
• A plastic spacer is inserted between the metal components. This creates a smooth gliding surface.
• The incision is closed using sutures or stitches.

2. Laparoscopic surgery:

• The surgeon makes several small keyhole incisions at the surgical site.
• A tube with a camera on one end, known as a laparoscope, and other small surgical instruments are inserted through these tiny incisions to carry out the procedure of total knee replacement.
• The procedure is less painful, has quicker healing, and has fewer complications than open surgery.

3. Robot-assisted surgery:

• The procedure is performed using a laparoscopic approach.
• The procedure is performed by robotic arms that are controlled by the surgeon who views the inside of the surgical site through a video monitor.
• The procedure is more precise than an open or laparoscopic technique.

Total knee replacement surgery may have the following complications:

• Infection
• Bleeding
• Scar tissue formation inside the knee
• Blood clot formation
• Blood vessel damage around the knee
• Nerve damage
• Allergic reaction to the anesthesia 
• Wearing down of the implant 
• Loosening of the implant 
• Persistent pain in the knee joint
• Need for another surgery 

1. The patient is usually discharged from the hospital one to three days after the surgery.
2. The patient’s physiotherapy sessions are started within 24 hours of the surgery.
3. Physiotherapy sessions need to continue for a few weeks after the surgery. They help in improving the patient's range of motion, muscle strengthening, and prevention of circulation problems.
4. The patient can start walking using a walker or crutches about two to three days after the surgery.
5. The patient will notice a significant improvement in mobility approximately one month after the surgery.
6. The patient can resume his/her daily activities three to six weeks after the surgery.
7. The patient should avoid heavy lifting and other strenuous activities for a couple of weeks after the surgery.
8. The patient should avoid any injury or fall during the recovery period.
9. Complete recovery after the surgery may take up to four months or more. 
10. The scar tissue may take as long as two years to heal completely.