Your knees must withstand a lot of pressure and work in your lifetime. The cartilage that protects the knee joint can start to wear down over time. This causes bone to rub against bone, which can be very painful. If this occurs, your doctor may recommend knee replacement surgery.

Surgery and medication

A knee replacement is a surgical procedure that’s done to replace a damaged knee, often worn down by osteoarthritis. This is usually considered a final intervention after other methods, such as pain relievers and knee joint injections, have failed. The success rates of joint replacements after 10 years are greater than 90 percent.

Medications that people receive after knee replacement surgery are given to minimize pain and nausea, prevent blood clots, and reduce the risks of surgical site infections. With time and an emphasis on early mobility, people who receive a knee replacement are finding relief and finally taking steps without pain and discomfort.

Pain control is very important after knee replacement surgery. If your pain isn’t managed well, you may have difficulty beginning rehabilitation and moving around after surgery. Rehabilitation and moving around after surgery are important because they improve the chances that your joint replacement is successful.

There are a number of methods your surgeon may use to manage your pain. Examples include:

Oral pain medications

These often include opioid pain medicines, such as:

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

These are commonly used as medicines to manage moderate to severe pain after surgery. However, taking too many opioid medications can cause:

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

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. Whenever you press the button, more medication is released. However, the pump is programmed so that it cannot deliver an excess of pain medicine. The dose is controlled over time. For example, a pump may be programmed so that you can’t receive more than a certain amount of morphine 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 they’re needed.

People who’ve received nerve blocks report higher satisfaction and fewer adverse events than those who’ve used a PCA pump. However, nerve blocks still have risks that include infection, allergic reaction, and bleeding. The nerve block also causes you to lose control of the muscles of 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, this medicine releases a continuous analgesic to relieve pain for up to 72 hours after your procedure. This medication may be prescribed along with other pain medications.

Having a knee replacement surgery increases your risk for blood clots after surgery. Blood clots are extremely dangerous because they can lodge in the heart or brain, resulting in a heart attack or stroke. A blood clot is known as a deep vein thrombosis (DVT). You’re at an increased risk of a DVT after surgery for the following reasons:

  • Your bones and soft tissue release proteins that aid in clotting during surgery.
  • You’re immobile during the surgery, which can promote the development of blood clots.
  • You don’t move around as much as you usually do after surgery.

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

  • compression stockings, which you wear on your calves or thighs
  • sequential compression devices, which gently squeeze your legs to promote blood return
  • aspirin, which is 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 besides aspirin, such as warfarin (Coumadin) and rivaroxaban (Xarelto)

There are several medications currently awaiting FDA approval to prevent postoperative blood clots. Examples include ximelagatran and razaxaban.

What medication your doctor prescribes often depends on your medical history, allergies, and risk of bleeding. Moving around shortly after your knee surgery is another great way to prevent blood clots and can enhance your recovery.

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

In one study, an estimated 55 percent of patients in the hospital needed treatment for nausea, vomiting, or constipation. Your doctor may prescribe antinausea medications, such as ondansetron (Zofran) or promethazine (Phenergan), if you experience nausea. Your doctor may also prescribe medications for constipation or stool softeners, such as:

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

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

Knee replacement surgery may temporarily cause pain, but the procedure can offer long-term pain reduction and greater mobility. Medications are available to keep your pain to a minimum, which can improve your mobility after surgery.