How Long Do Knee Replacements Last? The Truth.

Knee Surgery

Knee replacements are becoming increasingly popular for those suffering from advanced osteoarthritis. How long they last really depends on the quality of the prostheses, activity levels and quality of surgery.


1. How Long Do Knee Replacements Last?

Recovery from knee surgery can be daunting, so like many people you are probably wondering how long knee do replacements tend to last? Is it worth it? Knee replacements typically last 15-20 years after which another replacement may be required. This is why most surgeons prefer to operate on older patients as it is ideal not to require a second surgery. Outcomes are typically worse for those who have had multiple knee replacements.

To realize the full benefits of knee surgery, extensive rehabilitation is required. Typically this involves regular work with a physiotherapist for up to 6 months. It is not unusual for it to take up one year to maximize surgery results. For an in-depth examination of the typical knee replacement recovery timeline check this blogpost out.

The decision to get a knee replacement is significant and potentially life-changing. Before fully committing to the idea be sure to consider the following caveats regarding knee replacement surgeries.


2. Are You ACTUALLY a Good Candidate for Knee Replacement Surgery?

A 2014 analysis of ~5000 Americans who had undergone total knee replacement surgery showed that ⅓ of the operations were considered inappropriate1. Experts suggest that surgery should be considered viable only under specific criteria. The deciding factors include age, area of the knee that is affected, x-rays results, level of pain experienced day to day,  knee joint mobility and stability. To be an ideal candidate for total knee replacement surgery you should present with the following characteristics:

1) You are over 65 years of age

Knee prostheses have a lifespan of 15-20 years with normal use. Those who get there knee replaced a second time generally have a much higher rate of complications. Consquently, surgeons prefer to wait until one is older to minimize the need for another surgery in the future.

2) Your X-rays show advanced arthritis in your knee joint.

For knee replacement surgery to make sense, there must be observable damage to the joint itself. If you are experiencing significant pain, but actual damage to your knee joint appears negligible – there may be other factors at play. The progression of osteoarthritis is typically measured from your x-rays using the Kellgren Lawrence Osteoarthritis Criteria (0-4). Stage 3 and 4 are considered advanced.

3) Your arthritis is in two or more areas of the knee joint.

If you have uni-compartmental osteoarthritis, there are other non-surgical options to consider. Learn more about the anatomy of the knee joint here

4) Your knee is extremely immobile and feels unstable

Despite your discomfort if you are able to move freely and are maintaining a high quality of life a knee replacement may not provide a significant benefit.  

5) You are consistently experiencing intense pain

Knee replacements can make a big difference if you find that you are consistently experiencing debilitating pain. The WOMAC questionnaire is commonly used to evaluate knee dysfunction and pain in patients with osteoarthritis. A combined physical function and pain score greater than 23 is considered significant. See WOMAC here

Note that the absence of these characteristics does not mean that you should under no circumstance undergo knee surgery. It simply means that there may be alternatives solutions that are still viable apart from full knee replacement surgery.


3. Side Effects and Complications From Knee Replacement Surgery

Knee surgery is an invasive procedure that comes with risk both during and after. Approximately 2% of patients will have surgical complications, this number is higher for those with co-morbidities (e.g. diabetes & heart disease). The most common complications that occur during knee replacement surgery are:

  • Blood Clots: A lack of circulation to the lower area of leg below the knee can increase the risk of blood clots. This can be life-threatening should a blood clot break free and travel up the venous system into your lungs2.
  • Infection: like any surgery – infection is always a risk. This can occur superficially around the healing surgery wound or internally within the tissues surrounding the new prosthesis. The latter is more serious, and could result in another surgery2.

There are also issues that can occur with the implant itself during the recovery period or due to irregular use thereafter. Check out the full overview of the possible issues with knee prostheses here.


4. Alternatives to Knee Replacement Surgery

Most experts suggest exhausting your conservative alternatives before committing to a full knee replacement surgery. This is especially true for those that don’t fit the criteria for optimal candidacy. Knee surgery is a permanent alteration to your body, therefore once the decision is made, if the results weren’t what you were expecting there really isn’t any going back. Approximately 20% of knee replacement patients say they are unsatisfied with the final result3. For a comprehensive overview of all the treatments available for knee osteoarthritis, check out our osteoarthritis treatment guide.


5.Your Goals and Expectations from Knee Replacement Surgery

A common misconception that many have is that a knee replacement will feel like getting a brand new healthy knee. Unfortunately the functional benefits a knee replacement can offer are limited. To get a better understanding of exactly how much a knee replacement will benefit you requires understanding how scientists evaluate knee replacements in their studies.

Most studies follow up with knee replacement patients before and after the surgery at regular intervals. At each check-in the patient will undergo Functional Testing and Subjective Measures.

  • Functional Testing: Tests that evaluate a patient’s ability to perform simple physical tasks that represent the average demands encountered in daily life.
  • Subjective Measures: Tests that evaluate a patient’s perception of their ability to perform simple physical tasks, level of pain and stiffness.

In 2013 the Osteoarthritis Research Society International (OARSI) recommended the following functional tests to be used in evaluating patients at any stage suffering from osteoarthritis4.

  • 6 Minute Walk Test: Total distance covered in 6 minutes of comfortable walking
  • Shuttle Walking Test: Time required to Walk 4×30 ft. as fast as possible.
  • 30s Sit to Stand Test: The number of times patient can rise out and sit back down into a chair within 30s
  • Timed Get Up and Go Test: The amount of time it takes to get out of a chair, walk 9 feet, and then return to a seated position.

Subjective measures are generally questionnaires that will ask you 20-40 questions about the pain during or your ability to complete simple activities like walking or kneeling. Examples of common questions are:

  • In the last 48 hours how would you rate your pain getting in and out of cars?
  • In the last 48 hours how would you rate your pain bending to the floor?
  • In the last 48 hours how you rate your pain squatting to a chair?

The majority of the scientific studies that show improvement in knee function after knee replacement surgery use the measures described. Because of this knee replacement surgery has been extensively validated in its ability to improve the quality of life for those that struggle with basic movements. However, anything above and beyond that is much less clear. In fact, your surgeon will likely place you on permanent activity restrictions in an effort to preserve the integrity of the new prosthesis. Depending on your goals, you may have to consider other treatments in addition to, or instead of a full knee replacement. If you are someone that hopes to lead an active lifestyle after surgery consider the following:

  • At up to 18 months those with surgically replaced knees still exhibit a functional range of motion deficit of approximately ~30%5. This means that despite having much more flexibility in your knee joint, you wouldn’t use all of it during weight bearing movements like lunging and squatting. The likely cause is a lack of strength to support the joint at deeper knee angles. You may still require an external knee support or additional strength training to maximize the benefit of your knee replacement.
  • A 2008 study found that of those that undergo a full knee replacement 63% were able to return to their sport of choice after the surgery.7 Of those that returned 80% felt that the surgery improved their performance with 43% still experiencing pain during play.
  • Most individuals are able to quickly return to their job after surgery However, depending on the physical demands of your job you may require permanent modifications to your roles.

Being clear on what you are hoping to achieve after your surgery is beneficial for all parties involved in the decision-making process. If you are interested in learning more about knee surgery and other osteoarthritis treatments check out our comprehensive treatment guide. If you want to delay the need for surgery and are concerned about the side effects associated with long term use of pain killing drugs check out our guide to conservative treatment.

Looking to Avoid or Delay surgery?


References

  1. Riddle, D. L., Jiranek, W. A., & Hayes, C. W. (2014). Use of a validated algorithm to judge the appropriateness of total knee arthroplasty in the United States: a multicenter longitudinal cohort study. Arthritis & rheumatology, 66(8), 2134-2143.
  2. https://orthoinfo.aaos.org/en/treatment/total-knee-replacement/ (Accessed 2019 – 03 – 21)
  3. Kahlenberg, C. A., Nwachukwu, B. U., McLawhorn, A. S., Cross, M. B., Cornell, C. N., & Padgett, D. E. (2018). Patient satisfaction after total knee replacement: a systematic review. HSS Journal®, 14(2), 192-201.
  4. Dobson, F., Hinman, R. S., Roos, E. M., Abbott, J. H., Stratford, P., Davis, A. M., … & Hansen, P. (2013). OARSI recommended performance-based tests to assess physical function in people diagnosed with hip or knee osteoarthritis. Osteoarthritis and cartilage, 21(8), 1042-1052.
  5. McClelland, J. A., Feller, J. A., Menz, H. B., & Webster, K. E. (2017). Patients with total knee arthroplasty do not use all of their available range of knee flexion during functional activities. Clinical Biomechanics, 43, 74–78.doi:10.1016/j.clinbiomech.2017.01.022
  6. http://orthoinfo.aaos.org/topic.cfm?topic=a00357 (Accessed 2019 – 03 – 21)
  7. Hopper, G. P., & Leach, W. J. (2008). Participation in sporting activities following knee replacement: total versus unicompartmental. Knee Surgery, Sports Traumatology, Arthroscopy, 16(10), 973.