Arthritis Facts and Myths, Can You Tell Them Apart?

As I was perusing the first page of the 2,630,000 results from my most recent Google search, "arthritis myths", I came upon a quiz that entailed sorting out some common facts from myths about arthritis. Tapping into my inner competition seeker, I eagerly accepted the challenge. Be cautioned fellow science bloggers, I use the word "challenge" loosely as the 20 question quiz was hardly a deviation from common sense (for the most part). Although I would like to point out that there were a couple of questions that sparked my interest. 

SPOILER ALERT: This next section will delve deeper into the logic behind a few of the quiz questions and the answer(s) may be revealed. Take the quiz first here: Arthritis Quiz - Myth or Fact. or just read on.



Exhibit A: Knuckle-cracking can cause arthritis.  

I must admit that knuckle-cracking has never been a habit of mine until recently. It could be that I was constantly reprimanded by my grandparents who believed that cracking knuckles inevitably leads to arthritis. Considering grandparents only ever have your best interests at heart, I thought nothing of it and would even pass what I thought to be such a great piece of knowledge off onto my classmates at school. Needless to say the validity of a statement drops significantly with age of the person saying it. Not only did I receive strange looks, but nobody even took my advice! To this day I still am not sure as to whether they actually knew arthritis isn't associated with knuckle-cracking or if they just didn't care. Back then though, I couldn't help but be entertained with the thought that all those persistent knuckle-crackers were in for the worst arthritis of their lives come 50 years from then. I had warned them, but I was wrong. This led me to dig deeper into this myth and here is what I found.
Knuckle-cracking is done for a variety of reasons. Most might say they find it relieves pressure that has built up from frequent use of the fine motor skills, like perhaps writing for long periods of time. While others may simply find enjoyment in the so-called "cracking" sound we are all too familiar with.  The actual "cracking" sound heard comes from the popping of an air bubble that forms within the synovial fluid (joint lubricant) when the joints are pulled apart.¹ Those who write or type frequently may find relief in the popping of that air bubble to, say, relieve pressure within joints. Furthermore, as some of you knuckle-crackers may have experienced, it takes some force in order to produce the desired cracking sound and/or relief, and as one study found, knuckle-cracking can lead to swelling and minor pain due to the mechanical nature of the cracking.² Similarly, another study looked at the potential metacarpal-phalangeal osteoarthritic changes in geriatric patients with a history of knuckle-cracking and found no conclusive evidence of degenerative changes.³ As I continued my search to crack this myth I stumbled upon a man named Donald Unger, a medical doctor who authored a scientific paper on a study he performed on himself. He made it a point to crack the knuckles on only his left hand for half a century, leaving his right hand uncracked as a control and after analyzing his data, or his hands rather, he found no apparent difference between the two.⁴ So for all you knuckle-crackers, there is no need to rush to break the habit as no clear link between knuckle-cracking and arthritis has been found.

Myth = busted.

Exhibit B: Cold, damp weather causes arthritis.

This second myth caught my attention because it is another one of those that a good amount of people have heard of even though it's not actually true, at least not entirely. What do I mean by that? Well, we know that arthritis is a condition involving the loss of cartilage in the joints and can be categorized into three types: traumatic arthritis in which onset is triggered by injury, osteoarthritis in which onset is triggered by normal everyday wear and tear, and rheumatoid arthritis in which onset is triggered when the body makes antibodies that attack cartilage.⁵ Regardless of the type, those with arthritis usually experience pain, swelling and stiffness of joints due to the degeneration of the cartilage. This then, becomes the preface for those who believe that weather is indeed having a detrimental effect.

 -->As I was searching for some scientific facts to support this claim, a search bar that Weather.com has implemented immediately caught my attention. The idea is that you input your current location and the results will give you not only a forecast, but also "Today's Aches and Pains Index", a numerical scale they've developed that "forecasts the potential for weather-related aches and pains, especially in people with chronic health conditions (such as migraines or arthritis) that might make them sensitive to changes in weather conditions" and is defined as follows: Very High (9, 10), High (7, 8), Moderate (5, 6), Low (3, 4), Minimal (1, 2).-->⁶ Given a number on their scale, you can then infer how bad your symptoms of a chronic health condition may be that day. They also specify that the top three weather conditions that may be having this effect on symptoms are, chance of precipitation, humidity change, and temperature change.⁶ It could be that the change in pressure within the atmosphere could cause a change in pressure within the joints and thus swelling and/or pain. And the same could be said in regards to humidity and temperature with respect to joint pain, but whether or not these conditions are having a significant effect, has not scientifically been proven.⁷ 
Despite the fact that no direct link has been found, research in this area is difficult in general due to the mere fact that pain is relative. It is hard to determine that a high of 32 degrees with a 50% chance of rain is significantly causing a person's arthritis to worsen thus causing pain when pain tolerance between people can be very variable. Two people meeting the same criteria, with the same history may report two very different levels of pain under the same conditions making a completely controlled experiment invalid. Although as with anything, people will believe what they believe and just because the science can't back them up doesn't mean they are going to change their minds or ways. So, does the weather actually cause arthritis? No, but there is a slight chance that it could be worsening the symptoms.

Myth = mostly busted.
 
Sources:.

1. Bonafede, Peter. "Ask an Expert: Knuckle cracking and arthritis." Providence Health & Services. N.p., n.d. Web. 24 Oct. 2012. <http://oregon.providence.org/patients/programs/providence-medical-group-arthritis-center/pages/askanexpertlanding.aspx?templatename=ask+an+expert%3A+knuckle+cracking+and+arthritis&templatetype=askanexpert>. 
2. Castellanos, J, and D Axelrod. "Effect of habitual knuckle cracking on hand function.." Annals of Rheumatic Diseases 49.5 (1990): 308-309. BMJ Journals. Web. 24 Oct. 2012.
3. Swezey, Robert, and Stuart Swezey. "The Consequences of Habitual Knuckle Cracking." Western Journal of Medicine 122.5 (1975): 377-379. National Center for Biotechnology Information. Web. 24 Oct. 2012. 
4. Cracking joints. (2012, October 16). In Wikipedia, The Free Encyclopedia. Retrieved 06:29, October 25, 2012, from http://en.wikipedia.org/w/index.php?title=Cracking_joints&oldid=518120930
5. Lum, Grant. "Aches & Pains: Cold weather and effects on arthritis - The Weather Network." Current Weather - The Weather Network. N.p., n.d. Web. 25 Oct. 2012. <http://www.theweathernetwork.com/achespains/coldwx_arthritis>.  
6. "weather.com - Aches & Pains - Local Forecast." National and Local Weather Forecast, Hurricane, Radar and Report. N.p., n.d. Web. 29 Oct. 2012. <http://www.weather.com/outlook/health/achesandpains/weather/tenday/USWA0395?x=0&lswe=&lswa=&GO=GO&whatprefs=&from=aches_welcome&y=0>. 
7. Griffin, J. Morgan. "Arthritis and Weather." WebMD - Better information. Better health.. WebMD, 9 June 2003. Web. 29 Oct. 2012. <http://www.webmd.com/osteoarthritis/guide/arthritis-weather?page=3>.