Why do people get hip and knee replacements?

Arthritis, especially osteoarthritis (wear and tear arthritis) is the most common reason for joint replacements. Bones have a smooth gliding surface called cartilage on their ends, at joints. Osteoarthritis wears down the cartilage and the underlying bone gets exposed, causing inflammation within the joint, stiffness, pain, crunching and grinding. Bone-on-bone arthritis is when the cartilage is completely gone and the bones rub against each other.

There are many risk factors for arthritis, including age, obesity, genetics, systemic conditions like rheumatoid arthritis and lupus, prior surgeries, prior trauma like fractures, and in rare cases problems such as infection and gout.

Is joint replacement right for you?

People get joint replacements when they have debilitating hip or knee pain that interferes with their day-to-day life and causes them to alter the things they do on a routine basis because of that pain. Using x-rays, we confirm that the cause of the pain is arthritis and that replacement may be the right treatment.

Instead of jumping straight to surgery, we try non-surgical treatment options first. Some mainstays include weight loss, exercise and physical therapy, anti-inflammatory NSAIDs like Aleve, Advil and Motrin as well as Tylenol. Injections are also a mainstay. The most common injection is cortisone, but there are a few other options as well. Finally, there are other non-surgical treatment options in one-off cases.

Surgery is always a risk to the body, so we need to make sure that you’re healthy enough and that joint replacement is the right treatment for you. If you’re on dialysis or on home oxygen or have other severe medical conditions, you may be at very high risk for undergoing surgery.

How do hip and knee replacements work?

How hip replacements work

A hip replacement is replacing the ball and socket portion of the hip joint. The ball is the top portion of the femur and the socket is part of the pelvis. The major UK medical journal The Lancet called hip replacements the “operation of the century” because of how impactful and successful this operation has been.

Hip replacements may be done anterior (from the front) or posterior (from the back). There are pros and cons to both, but overall both provide an excellent hip replacement with no long-term difference in outcomes. You’ll discuss with your doctor about which option they’re most comfortable with in your situation.

Hip replacements have excellent long-term results. We’ve been continuously improving them since we started doing replacements in the 1960s. There are rare complications, like infection, dislocation, leg length difference, and fracture. You’ll want to discuss risks with your doctor, but the complications are very rare.

How knee replacements work

Knee replacements are similar to hip replacements. You are reshaping the end of the femur (thigh bone) and top of the tibia (shin bone) and replacing that with the combination of metals and plastics. There’s a standard approach (entry) through the front of the knee. Implants may be done cemented, which is more common, or cementless, which is newer.

Both cemented and cementless have pros and cons. The cemented is the current gold standard, with a long record of success, and works in most patients. There is a risk that over a few decades the cement may start to come loose from the bone. The cemented is newer technology, but your bone grows into the implant so long-term we think it stays in place better. However, you need to have healthy enough and strong enough bone to use a cementless, so it is only the right answer for some patients.

Knee replacement has a more difficult first few weeks after surgery than hip replacement does, but like hip replacement it has excellent long-term results over decades. Again, there are rare complications like infection, stiffness, instability, or the implants coming loose from the bone, and you should discuss the risk with your doctor.

What is the process to get a replacement?

History of replacements

In the 1960s and 1970s, you would donate blood before the surgery, to be transfused back during surgery, and be pre-admitted to the hospital for prehab and blood work. After surgery you’d be in bed, sometimes for weeks, as you started to heal. Finally, you’d spend a good portion of your rehabilitation time in the hospital.

In the 1980s and 1990s, surgeries shifted towards shorter stays and fewer transfusions. We found that patients were doing well with more limited hospital stays.

In the early 2000s, surgeons pioneered rapid recovery and started doing outpatient joint replacement. We found patients who got up and moved with modern implants were doing better, so stays became shorter, fewer blood transfusions were performed, and rehab started earlier.

In recent years, outpatient surgery, where you have surgery and go home the same day, has exploded. Outpatient surgery leaves hospital beds available for critically ill patients, which was essential during covid. As outpatient surgery options spread, it has become very popular.

What does outpatient joint replacement look like?

  1. You have a clinic appointment, and you and your surgeon decide to have a hip or knee replacement.
  2. You obtain medical clearance. This may be as simple as reviewing your conditions and deciding that it is safe, using risk assessment tools. If you have more complex health needs, we may need to talk with your specialists.
  3. We set you up with equipment for home and medications.
  4. You attend the education class and pre-surgery therapy visit so you can know the expectations after surgery.
  5. You come to the hospital or surgery center, have the surgery, and go home the same day.
  6. You receive pain control and physical therapy with help from your support system, who may be family, friends, spouse, neighbors, or anyone who can help especially immediately after surgery.

Benefits of outpatient joint replacement

Patients love outpatient joint replacement, and studies show there is increased satisfaction compared with staying in the hospital. The benefits of outpatient joint replacement include:

  • Lower infection risk. Infection risk for outpatient replacements is lower, partially due to not being in a hospital with sick people and partially due to patients having outpatient surgery being slightly healthier overall.
  • Comfortable recovery. You’re able to recover comfortably at home, in your own bed and your own space. Being at home forces you to move more than you would in the hospital, which helps you recover quicker.
  • Lower costs. Going home the same day eliminates many of the charges.
  • No hospital food. You’re able to enjoy your favorite foods, made the way you like them.

Who should have outpatient surgery?

The ideal patient for outpatient surgery should have:

  • Strong support network
    • Your support network may be family, friends, spouse, neighbors, or anyone you’re close to who can help, especially the first few days
  • Home set up for success
    • Equipment ready
    • Transportation arranged to and from the surgery, doctor visits, and physical therapy
    • Opportunity to live on a single level after surgery (if available)
  • Well-controlled or minimal medical conditions
    • Well-controlled blood pressure, diabetes, etc.
    • Not actively trying new medications to get a condition under control
  • No preoperative opioid medications
    • Opioid medications before surgery are a risk factor for having to be readmitted after surgery
  • Self-motivation
    • Taking an active role in your own care is very important with outpatient surgery

Which patients should stay in the hospital overnight?

Patients should stay in the hospital overnight if they have:

  • Less support at home
  • Medical issues that need close monitoring
  • Long-term use of opioids
  • Complex replacements or revisions, which are bigger surgeries

Which patients should go to a nursing home or rehab facility?

Ideally, no patients would go to a nursing home or rehab. Studies show these places have worse patient outcomes, higher infection rates, higher costs, and a slower recovery. In certain circumstances these facilities are unavoidable, but we try to get patients home either the same day or after a short hospital stay.

Frequently Asked Questions

What is the recovery time after an outpatient joint replacement?

It takes patients several weeks to recover from the pain of a hip or knee replacement surgery and start working on your strengthening, mobility, and movement. The bulk of the recovery is in the first few months, and you continue working on your strength, your endurance, and your balance for the first year after surgery. With hip replacements it takes about a month to turn that first corner, while with knee replacements it takes about a month and a half.

Am I eligible for a knee replacement if the interior of the knee is bone-on-bone but there is still cartilage on the exterior?

Yes, you may be eligible for either a partial knee replacement or total knee replacement, depending on the specifics. You are describing medial arthritis, the most common pattern of arthritis. A partial knee replacement only replaces the side of the knee that is worn down, but it’s not right for every patient. An x-ray may show cartilage left in a knee, but the cartilage may not be healthy, so a total knee replacement makes more sense.

If I have a torn labrum, should I get a hip replacement?

The labrum is an O-ring around your hip socket that deepens the hip joint. It’s part of the cartilage structure. The labrum can get pinched as your hip moves. As you get arthritis, the labrum starts to see more stress and tears can develop. In that case, a hip replacement is usually a good option.

If it’s a labrum tear in isolation, without much hip arthritis, then physical therapy or sometimes arthroscopic surgery to repair the tear itself are good options.

If the ACL and MCL were torn decades ago, how will they fit with a total knee replacement?

We remove the ACL in all knee replacements. The geometry and implant design of the traditional knee replacement implant provides stability once we take the ACL out. However, we rely on the MCL, on the inside of your knee, to give stability to the knee side-to-side.

During your physical exam, your doctor would see how strong your MCL is. If it was repaired well and healed well, then you could have a traditional knee replacement. If the MCL wasn’t working or had a lot of laxity, you would receive a different kind of knee replacement that has internal stability and doesn’t rely on the MCL.