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7 Most Common Symptoms of a Loose Knee Replacement

Walking became impossible.  Each step was associated with severe pain.  Knee replacement seemed like a good solution.  Unfortunately, months after the surgery problems exist.  Your doctor thinks you have a loose knee replacement.  What is a knee replacement?  What causes a knee replacement to become loose?  What are the 7 most common symptoms of a loose knee replacement?  How successful is knee replacement surgery?  What are the risks of knee replacement? Is there a knee replacement alternative?  Let’s dig in.

What Is a Knee Replacement?

A knee replacement, also known as knee arthroplasty is a surgical procedure where the actual knee joint is surgically cut out and replaced with an artificial joint. The artificial joint can also be called a prosthesis.   There are many types and manufacturers of artificial knee joints.  Examples include Zimmer, Biomet, Depuy, and Stryker.  After the damaged knee joint is cut out a metal rod is inserted into both the thigh and shin bone that serves as an anchor for the new joint.  This rod is then glued into position with special surgical cement.  The prosthesis attaches to the rod.  The procedure which takes approximately 1.5-2 hours can be performed in a hospital or outpatient surgical center.  A general anesthetic or spinal block is required.

What Causes a Knee Replacement to Become Loose? (Excessive wear, infection, fractures, misalignment, technical failures)

Loosening is one of the most common complications of total knee replacement surgery. Patients usually need revision surgery to fix it.  What that means is another surgery is required to address the loose knee replacement.  There are many causes for a knee replacement to become loose.  The 6 most common are:

Excessive Wear

Knee replacements do not last forever.   The longevity of knee replacement depends upon many factors including the type of implant, age, and gender of the patient, diagnosis, and type of fixation (1). The majority of knee replacements last approximately 20-25 years (2).  The actual implant can become worn out.


Infection can occur immediately after surgery or years later.  The infection can affect the skin, muscles, and the artificial joint.   This can compromise the cement that glues the artificial joint to the bone. When this occurs the knee replacement can become loose.


Fracture on the thigh bone (femur)

During knee replacement surgery, the end of the thigh bone is amputated.  A hole is then drilled into the end of the thigh bone.  A metal stud is then hammered into the thigh to which the new knee joint is attached.  If the bone is weak such is the case with patients with osteoporosis or if too aggressive, a fracture can occur.  The end result can be a loose knee replacement.

Poor Alignment

Many patients with knee arthritis have misaligned knees.  Some individuals are bow-legged (varus) whereas others are knock-kneed. (valgus).  Knee replacements must be properly aligned.  Often times at the time of surgery there is poor alignment of the artificial knee joint.  This misalignment can cause the knee replacement to become loose.

Technical Failure

After cutting out the knee joint the knee prosthesis is glued into the thigh and shin bone.  If the insertion of the prosthesis is incorrect or there is inadequate cement the knee replacement can become loose.  Lawsuits have claimed that the DePuy Attune implant loosened because the cement that was used to connect the knee replacement to the bone failed (3).  Zimmer NexGen implant has also had problems leading to a recall of 68,000 devices (4).


Some patients are allergic to the glue or the actual knee prosthesis.  This can cause a number of symptoms including persistent swelling, redness, and reduced range of motion.  In severe cases, the knee implant can become loose.

7 Most Common Symptoms of a Loose Knee Replacement


Pain is the most common of the symptoms of a loose knee replacement. The loose prosthesis, in addition to no longer functioning as a stable joint, places additional forces on the surrounding muscles, tendons, and ligaments.  The end result is pain.


Swelling in the right knee identified by the black arrow

A loose knee replacement can cause the knee to swell.  This is also known as water on the knee.  Oftentimes the excessive fluid on the knee is drained in an effort to decrease the pain. Unfortunately, it reaccumulates quickly.

Difficulty Walking

A loose knee replacement creates an unstable joint which makes walking difficult.


A knee replacement that becomes loose compromises the stability of the knee joint.  Many patients feel as though their knee wants to “give out”.  This is particularly problematic while standing, walking, or going up or downstairs.

Redness and Warmth

A loose knee replacement can be a constant source of irritation and inflammation.  The result is persistent redness and warmth despite conservative care.

Painful Popping

A loose knee replacement is unstable and creates excessive motion in the knee joint.  This excessive motion can result in the painful popping of the supporting ligaments and tendons. Ouch!

Reduced Range of Motion

Many patients with a loose knee replacement complain of reduced range of motion. That means that they can not fully bend or flex the knee. This is typically due to excessive fluid and a malfunctioning knee joint.

What Is the Actual Success of Knee Replacement Surgery?

Knee replacement surgery is a common orthopedic procedure. More than 670,000 knee replacement surgeries are performed annually (5).   Does it work?  Credible high-level evidence is essential to understanding the actual success of the surgery. The gold standard in research is a randomized controlled trial study (RCT).  A randomized controlled trial study is a scientific trial in which subjects are randomly assigned to one of two groups:  the experimental group receiving the intervention being tested or the control. The goal is to reduce bias when testing the effectiveness of new treatments. Is there such a study that examined the effectiveness of knee replacement surgery?

Absolutely!  The best study to date performed on knee replacement is a 2015 RCT that compared knee replacement to physical therapy(5).  95 patients with moderate to severe knee Arthritis who were eligible for knee replacement surgery were randomized into the two groups.  In the first group, patients underwent knee replacement followed by 12 weeks for physical therapy.  In the second group, patients received 12 weeks of physical therapy.  This showed some interesting things.

  • 3 in 4 patients in the physical therapy group decided not to get a knee replacement
  • About half of the knee replacement group reported some sort of serious complication
  • While the knee replacement group had better functional improvement than physical therapy in some tests, in others there was no difference
  • You needed to perform 6 knee replacements before one person reported that they had at least 15% better function (this is called an NTT of 6)

What Are the Risks of Knee Replacement?

A loose knee replacement is but one of the many complications.  Knee replacement is a major surgery in which the damaged knee joint is literally amputated.  The most common knee replacement surgery complications are:

  • Infection (6)
  • The need for a second surgery (revision), which happens in about 6% of patients (7)
  • Knee replacement patients are 9 times more likely to have a heart attack (8). The risks go up from there with almost 20% of patients with a prior serious cardiac history having heart side effects after the surgery (9).
  • A build-up of toxic metal ions in the blood (10)

How to Avoid a Loose Knee Replacement?

Don’t have the knee replacement surgery.  Dig deep, understand the problem/problems with your knees, and evaluate all nonsurgical treatment options. Realize that once the joint is amputated there is no turning back.  If you are dissatisfied with your results you can’t ask for your knee back.  The mechanics of the knee joint are changed forever after knee replacement surgery.

Is There a Knee Replacement Alternative?

The Centeno-Schultz Clinic has been injecting bone marrow concentrate which contains your own stem cells for the last 16 years in the treatment of knee arthritis.  The goal is to help patients avoid knee replacement surgery and the complications therein.  We recently published a similar RCT to the one described above where the less invasive injection-based technique was compared to physical therapy. More than 2/3rds of the patients met the functional criteria for success at 2 years out (11).  Our real-time patient registry provides an in-depth analysis of our results based upon the area of the body, function, pain reduction over time.  To learn more please click here.

Any new advances?  Absolutely!  We have been meticulous in the treatment of patients with knee osteoarthritis.  This starts with acknowledging that the body is a complex system with many moving parts that work together.  For the best results, we evaluate the patient in total as opposed to just the knee. We use the SANS approach.  We evaluate Symmetry, Articulation, Neurologic, and Stability.  To learn more about this comprehensive approach please click here.

Want to Get Back to What You Love, Without Surgery and Medication?

To learn more and review MRI results before and after treatment with bone marrow-derived stem cells please click on the video below.

Symptoms of a Loose Knee Replacement

Recently we established a new standard in the treatment of knee arthritis.   How?   Based upon a landmark study from Phillipe Hernigou in Paris France we are now injecting stem bone marrow concentrate which contains your own stem cells directly into the knee bones (12). The procedure is called an interosseous injection.  This is in addition to injecting other important structures such as ligaments, tendons, cartilage surfaces, and meniscus.  Why?  Because we are committed to providing our patients the very best clinical outcomes

In Conclusion

A knee replacement, also known as knee arthroplasty is a major surgery in which your damaged knee is amputated and replaced with an artificial joint.

The artificial knee joint is glued into position with special surgical cement.

Why does a knee replacement become loose?  The most common causes include:

  • Excessive wear
  • Infection
  • Fractures
  • Poor alignment
  • Technical Failure
  • Rejection

A knee replacement can become loose and when this occurs it is a major problem.  The 7 most common symptoms of a loose knee replacement are:

  • Pain
  • Swelling
  • Difficulty Walking
  • Instability
  • Redness and Warmth
  • Painful Popping
  • Reduced range of motion

Don’t believe the glossy ads and Dr. Google claims.  A high-level randomized control study comparing knee replacement vs physical therapy questions the actual success of knee replacement.

There are significant risks associated with knee replacement which include infection, revision, heart attack, and build-up of toxic ions.

The best way to avoid a loose knee replacement is to NOT have the surgery.

The Physicians at the Centeno-Schultz Clinic are experts in the treatment of knee osteoarthritis and other common injuries.  Treatment options include including stem cells and PRP into the areas of damage.  Our clinical results have been published and are available online.

If you or a loved one have knee pain and ongoing limitations please schedule a telemedicine schedule new patient consultation where you can learn what regenerative treatment options are best for you.  We are experts in the field and will compassionately listen to you and your loved ones.

1.Rand JA, Trousdale RT, Ilstrup DM, Harmsen WS. Factors affecting the durability of primary total knee prostheses. J Bone Joint Surg Am. 2003 Feb;85(2):259-65. doi: 10.2106/00004623-200302000-00012. PMID: 12571303.

2.Evans JT, Walker RW, Evans JP, Blom AW, Sayers A, Whitehouse MR. How long does a knee replacement last? A systematic review and meta-analysis of case series and national registry reports with more than 15 years of follow-up [published correction appears in Lancet. 2019 Feb 20;:]. Lancet. 2019;393(10172):655-663. doi:10.1016/S0140-6736(18)32531-5


4.Pellerin C, Adamson M, Janney C. Recall Rates of Total Knee Arthroplasty Devices Are Dependent on the FDA Approval Process. Cureus. 2020;12(8):e9744. Published 2020 Aug 14. doi:10.7759/cureus.9744

5. Skou ST, Roos EM, Laursen MB, Rathleff MS, Arendt-Nielsen L, Simonsen O, Rasmussen S. A Randomized, Controlled Trial of Total Knee Replacement. N Engl J Med. 2015 Oct 22;373(17):1597-606. doi: 10.1056/NEJMoa1505467

6.Peersman G, Laskin R, Davis J, Peterson M. Infection in total knee replacement: a retrospective review of 6489 total knee replacements. Clin Orthop Relat Res. 2001 Nov;(392):15-23.

7.Pabinger C, Berghold A, Boehler N, Labek G. Revision rates after knee replacement. Cumulative results from worldwide clinical studies versus joint registers. Osteoarthritis Cartilage. 2013 Feb;21(2):263-8. doi: 10.1016/j.joca.2012.11.014.

8. Lu N, Misra D, Neogi T, Choi HK, Zhang Y. Total joint arthroplasty and the risk of myocardial infarction: a general population, propensity score-matched cohort study. Arthritis Rheumatol. 2015;67(10):2771–2779. doi: 10.1002/art.39246

9.Feng B, Lin J, Jin J, Qian W, Cao S, Weng X. The Effect of Previous Coronary Artery Revascularization on the Adverse Cardiac Events Ninety days After Total Joint Arthroplasty. J Arthroplasty. 2018 Jan;33(1):235-240. doi: 10.1016/j.arth.2017.08.011.

10. Friesenbichler J, Maurer-Ertl W, Sadoghi P, Lovse T, Windhager R, Leithner A. Serum metal ion levels after rotating-hinge knee arthroplasty: comparison between a standard device and a megaprosthesis. Int Orthop. 2012;36(3):539–544. doi: 10.1007/s00264-011-1317-4

11.Centeno C, Sheinkop M, Dodson E, et al. A specific protocol of autologous bone marrow concentrate and platelet products versus exercise therapy for symptomatic knee osteoarthritis: a randomized controlled trial with 2 year follow-up. J Transl Med. 2018;16(1):355. Published 2018 Dec 13. doi:10.1186/s12967-018-1736-8

12.  Hernigou P, Bouthors C, Bastard C, Flouzat Lachaniette CH, Rouard H, Dubory A. Subchondral bone or intra-articular injection of bone marrow concentrate mesenchymal stem cells in bilateral knee osteoarthritis: what better postpone knee arthroplasty at fifteen years? A randomized study. Int Orthop. 2020 Jul 2. doi: 10.1007/s00264-020-04687-7. Epub ahead of print. PMID: 32617651.


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