Your Knee Pain Is Most Likely Due to Knee Arthritis Nerve Pain
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Modern orthopedics is all about structure. However, there’s a big problem with this focus. Recent research shows that this model is seriously flawed. For example, it’s an urban myth that cartilage loss in the knee is associated with knee pain, and most orthopedic surgeons today replace knees based on this assumption. The problem with the assumption is that studies show the same type of cartilage loss in patients with no pain. What then is the culprit? Knee arthritis nerve pain.
Why Knee Replacement Is Usually a Bad Idea
Pain is typically the driving force behind the decision to get a knee replacement, and most orthopedic surgeons have it all wrong when it comes to the cause of your knee pain. How do we know this? Of course, there’s the research, but an even more direct indicator is that so many knee-replacement patients are still in pain after the procedure. Here are some studies:
- Chronic knee pain is the most common complaint following knee replacement1.
- Pain rates worsen as time goes on—studies have followed out as far as four years following knee replacements2.
- Knee pain could be due nerves traced to an issue in your back3.
In addition to chronic pain, there are many risks and other problems associated with knee replacement. Only 1 in 20 patients with knee replacement are eventually able to function at normal activity levels4. Younger knee-replacement patients (those age 55 and younger) typically experience more pain and wear out the artificial joint faster5.
Allergies to the prosthesis can be an issue as well. Normal wear and tear can cause the knee-replacement device to shed metal particles, causing a buildup of ions in the blood6. In fact, if you already have allergies to any metal, such as those in jewelry, you could also be allergic to the metal in the artificial knee. Taking that a step further, if you have allergies to anything (e.g., pet dander, pollen, etc.), allergic reactions to the artificial knee are more likely7. The new plastics used in these knee devices can also induce an allergic response8.
If ongoing pain and these other risks aren’t enough, there’s much more:
- Spinal-fracture risk increases following knee replacement.
- Hip-fracture risk increases for up to 10 years following a knee replacement.
- Heart attack, stroke, and blood clots are a severe risk following a knee replacement.
As you can see, there are a lot of risks involved in a knee replacement, and the findings in this newest study suggest these surgeries are being performed based on a flawed orthopedic pain model.
The Phenomenon Known as Temporal Summation
I’ll discuss the new research in just a moment, but to understand this study, you need to know what temporal summation (aka wind-up and central sensitization) is. At the basic level, it occurs when the nervous system amplifies pain signals. This ramp up is a good thing when an injury is acute, or when it first occurs because it helps you keep weight off of the affected body part or not let anything touch the area as it heals. However, these amplified pain signals are a bad thing when the pain is chronic because it makes the affected area feel much more painful. In temporal summation, individual painful events get lumped together and magnified, or blown way out of proportion.
The New Study: Knee Arthritis Nerve Pain
For this new study9, researchers induced pain in knee arthritis patients and found that their structure didn’t account for their pain levels. So what did? Their nerve hypersensitivity. Once again, this demonstrates that knee arthritis pain is more about the nerves than what the X-ray or MRI shows the knee structure. The study concluded that “the temporal summation of pain response… is not explicable by a specific time-dependent behaviour of stress and strain in the activated deep tissue and hence not due to changes in tissue biomechanics.”
Knowing that this study showed that knee arthritis pain is more about nerves and not about the mechanics of the knee, this likely explains why many times after the knee is amputated and a prosthesis is inserted (knee replacement), many patients still report significant knee pain. In fact, the most commonly reported pain number on the pain scale after a knee replacement is a whopping 5 out of 10.
The upshot? This new study showing knee arthritis pain due to nerves, as opposed to knee arthritis pain due to tissue mechanics, would likely come as a big surprise to your surgeon. It’s why many times we see that replacing the old knee with a new one doesn’t address the knee arthritis nerve pain, and if this radical surgery, associated with so many complications and risks, isn’t addressing the real cause of the pain, what’s the point?
- Sakellariou VI, Poultsides LA, Ma Y, Bae J, Liu S, Sculco TP. Risk Assessment for Chronic Pain and Patient Satisfaction After Total Knee Arthroplasty. Orthopedics. 2016 Jan-Feb;39(1):55-62. doi: 10.3928/01477447-20151228-06. Epub 2016 Jan 5. PMID: 26730683.
- Schroer WC, Diesfeld PJ, LeMarr AR, Morton DJ, Reedy ME. Functional Outcomes After Total Knee Arthroplasty Correlate With Spine Disability. J Arthroplasty. 2016 Sep;31(9 Suppl):106-9. doi: 10.1016/j.arth.2016.06.015. Epub 2016 Jun 23. PMID: 27452138.
- Wylde V, Hewlett S, Learmonth ID, Dieppe P. Persistent pain after joint replacement: prevalence, sensory qualities, and postoperative determinants. Pain. 2011 Mar;152(3):566-72. doi: 10.1016/j.pain.2010.11.023. Epub 2011 Jan 15. PMID: 21239114.
- Kahn TL, Schwarzkopf R. Does Total Knee Arthroplasty Affect Physical Activity Levels? Data from the Osteoarthritis Initiative. J Arthroplasty. 2015 Sep;30(9):1521-5. doi: 10.1016/j.arth.2015.03.016. Epub 2015 Mar 31. PMID: 25882608.
- Valdes AM, Doherty SA, Zhang W, Muir KR, Maciewicz RA, Doherty M. Inverse relationship between preoperative radiographic severity and postoperative pain in patients with osteoarthritis who have undergone total joint arthroplasty. Semin Arthritis Rheum. 2012 Feb;41(4):568-75. doi: 10.1016/j.semarthrit.2011.07.002. Epub 2011 Aug 24. PMID: 21868060.
- 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 Mar;36(3):539-44. doi: 10.1007/s00264-011-1317-4. Epub 2011 Jul 14. PMID: 21755331; PMCID: PMC3291763.
- Hinarejos P, Ferrer T, Leal J, Torres-Claramunt R, Sánchez-Soler J, Monllau JC. Patient-reported allergies cause inferior outcomes after total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc. 2016 Oct;24(10):3242-3246. doi: 10.1007/s00167-015-3837-8. Epub 2015 Nov 3. PMID: 26531183.
- Utzschneider S, Lorber V, Dedic M, Paulus AC, Schröder C, Gottschalk O, Schmitt-Sody M, Jansson V. Biological activity and migration of wear particles in the knee joint: an in vivo comparison of six different polyethylene materials. J Mater Sci Mater Med. 2014 Jun;25(6):1599-612. doi: 10.1007/s10856-014-5176-6. Epub 2014 Feb 22. PMID: 24562818.
- Manafi-Khanian B, Kjaer Petersen K, Arendt-Nielsen L. Tissue mechanics during temporal summation of sequentially cuff pressure-induced pain in healthy volunteers and patients with painful osteoarthritis. Eur J Pain. 2017 Jul;21(6):1051-1060. doi: 10.1002/ejp.1006. Epub 2017 Feb 9. PMID: 28182316.