During a total knee replacement, a surgeon will remove damaged tissue and implant an artificial knee joint.

Surgery can reduce pain and increase mobility in the long term, but pain will be present immediately after the procedure and during recovery.

People usually feel fully comfortable again after 6 months to a year. Meanwhile, medication can help them manage the pain.

Most people have knee replacement surgery under a general anesthetic.

However, from the time they awaken, they will need pain relief and other types of medication to help them manage discomfort and reduce the risk of complications.

Medications after knee replacement surgery can help you:

  • minimize pain
  • manage nausea
  • prevent blood clots
  • lower the risks of an infection

With appropriate treatment and physical therapy, many people recover from a knee replacement and are able to return to their everyday activities within weeks.

Without adequate pain management, you may have difficulty starting rehabilitation and moving around after surgery.

Rehabilitation and mobility are important because they improve the chances of a positive outcome.

Your surgeon may choose from various options, including:

  • opioids
  • peripheral nerve blocks
  • acetaminophen
  • gabapentin/pregabalin
  • non-steroidal anti-inflammatories (NSAIDs)
  • COX-2 inhibitors
  • ketamine

Find out more about pain medication for a total knee replacement.

Oral pain medications

Opioids can relieve moderate to severe pain. A doctor will usually prescribe them alongside other options.

Examples include:

  • morphine
  • hydromorphone (Dilaudid)
  • hydrocodone, present in Norco and Vicodin
  • oxycodone, present in Percocet
  • meperidine (Demerol)

However, taking too many opioid medications can cause:

  • constipation
  • drowsiness
  • nausea
  • slowed breathing
  • confusion
  • a loss of balance
  • an unsteady gait

They can also be addictive. For this reason, a doctor will not prescribe opioid medications for longer than you need.

Patient-controlled analgesia (PCA) pumps

Patient-controlled (PCA) pumps usually contain opioid pain medications. This machine will allow you to control the dose of your medication.

When you press the button, the machine releases more medication.

However, the pump controls the dose over time. It is programmed so that it cannot deliver too much. This means you can’t receive more than a certain amount of medication per hour.

Nerve blocks

A nerve block is administered by inserting an intravenous (IV) catheter into areas of the body near nerves that would transmit pain messages to the brain.

This is also known as regional anesthesia.

Nerve blocks are an alternative to PCA pumps. After one to two days, your doctor will remove the catheter, and you can begin taking pain medicines by mouth if you need them.

People who’ve received nerve blocks have reported higher satisfaction and fewer adverse events than those who’ve used a PCA pump.

However, nerve blocks can still entail some risks.

They include:

  • infection
  • an allergic reaction
  • bleeding

The nerve block can also affect the muscles in the lower leg. This may slow your physical therapy and ability to walk.

Liposomal bupivacaine

This is a newer medication for pain relief that a doctor injects into the surgical site.

Also known as Exparel, it releases a continuous analgesic to relieve pain for up to 72 hours after your procedure.

The doctor may prescribe this drug along with other pain medications.

After knee replacement surgery, there is a risk of developing a blood clot. A clot in the deeper blood vessels is called deep vein thrombosis (DVT). They usually occur in the leg.

However, a clot can sometimes break off and travel around the body. If it reaches the lungs, it can result in pulmonary embolism. If it reaches the brain, it can lead to a stroke. These are life-threatening emergencies.

There is a higher risk of DVT after surgery because:

  • Your bones and soft tissue release proteins that aid in clotting during surgery.
  • Being immobile during surgery can reduce blood circulation, increasing the chance that a clot will develop.
  • You won’t be able to move around very much for a while after surgery.

Your doctor will prescribe medications and techniques to reduce the risk of blood clots after surgery.

These could include:

  • compression stockings, to wear on your calves or thighs
  • sequential compression devices, which gently squeeze your legs to promote blood return
  • aspirin, an over-the-counter pain reliever that also thins your blood
  • low-molecular-weight heparin, which you can receive by injection or through a continuous IV infusion
  • other injectable anticlotting medications, such as fondaparinux (Arixtra) or enoxaparin (Lovenox)
  • other oral medications such as warfarin (Coumadin) and rivaroxaban (Xarelto)

The options will depend on your medical history, including any allergies, and whether you have a risk of bleeding.

Doing exercises in bed and moving around as soon as possible after knee surgery can help prevent blood clots and enhance your recovery.

Blood clots are one reason why complications occur after knee replacement surgery. Find out more about other possible complications.

Infection is another serious complication that can arise during knee replacement surgery.

In the past, around 1 in 20 people developed an infection, but the current rate is around 1.1 percent. This is because surgeons now give antibiotics before surgery, and they may continue to give them for 24 hours after.

People with diabetes, obesity, circulatory problems, and conditions that affect the immune system, such as HIV, have a higher risk of getting an infection.

If an infection develops, the doctor will prescribe another course of antibiotics.

If this happens, it is essential to take the whole course of treatment, even if you feel better. If you stop a course of antibiotics partway through, the infection may return.

In addition to medications to reduce pain and risks of blood clots after knee replacement, your doctor may prescribe other therapies to minimize the side effects of anesthesia and pain medicines.

In one study, around 55 percent of people needed treatment for nausea, vomiting, or constipation after surgery.

Antinausea medications include:

  • ondansetron (Zofran)
  • promethazine (Phenergan)

Your doctor may also prescribe medications for constipation or stool softeners, such as:

  • docusate sodium (Colace)
  • bisacodyl (Dulcolax)
  • polyethylene glycol (MiraLAX)

You may also receive additional medications if you need them. This could include a nicotine patch if you smoke.

Knee replacement surgery can increase pain for a while, but the procedure can improve pain and mobility levels in the long term.

Medications can help keep pain to a minimum, and this can improve your mobility after surgery.

If you experience any symptoms or adverse effects after a knee replacement, it is best to speak to a doctor. They can often adjust a dose or change the medication.