When you press, twist, squeeze, or pull on your fingers, you get that satisfying crack sound. For some people it鈥檚 a force of habit, others just like the feeling. Whether you just wince at the sound, or do it yourself, you鈥檙e likely familiar with knuckle cracking. If you鈥檙e like me and you can鈥檛 go more than a couple hours before that satisfying pop of the joints in your hand, you鈥檙e also familiar with the scolding that comes with it. 鈥淪top that nasty habit or you鈥檒l get arthritis.鈥� Is cracking your knuckles as bad as it sounds?
Are 36 500 cracks enough to prove a point?
A fellow knuckle-cracker, Dr. Daniel Unger, faced the same scolding and decided to conduct his own study. For 50 years, he deliberately cracked the knuckles on his left hand at least twice a day and used his right hand as a control. In his paper, 鈥�鈥� he reported that after 50 years of cracking knuckles on the left hand and sparing the right, there were no apparent differences in arthritic symptoms.
Let鈥檚 Knuckle Down
Each has 27 bones: eight carpals which make up your wrist, five metacarpals in your mid-hand (the palm part), and 14 phalanges (the fingers). Each finger has three phalanges (with the exception of the thumb, with two), that you can easily identify yourself if you bend your finger into a hook shape. The junction between two bones is called a joint, with 鈥渒nuckle鈥� being the blanket term for all the joints in the hands. Each joint has a name determined by the bones they separate. The joint between carpal and metacarpal bones is the carpometacarpal joint. Between the metacarpals and phalanges is the metacarpophalangeal (MCP) joint. And between each phalange is an interphalangeal (IP) joint. Pretty simple, right? That鈥檚 why my anatomy professors always told me to just guess if I was ever stuck on an exam. When it comes to cracking knuckles, most people are referring to the MCP and the IPs, where the finger meets the palm, and where your finger bends in half, respectively.
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While Dr. Unger鈥檚 study was long-term and controlled, it only had one subject. Luckily, there has been more research on the topic since. A paper in 1990 could not find any causal link between knuckle cracking and arthritis when comparing the MCP joints of 300 patients. In fact, they found indications for arthritis in many people who don鈥檛 crack their knuckles at all. However, they did explain that knuckle cracking was linked to more hand swelling and lower grip strength, meaning that it wasn鈥檛 a positive habit for overall hand function. This disproved the old wives tale but didn鈥檛 remove all fear of the habit. Another study published in 2011 used radiography to assess the prevalence of arthritis in 215 people, 20% of whom were knuckle crackers. The prevalence of arthritis in any joint was the same in subjects who crack their knuckles (18%) and those who don鈥檛 (21%). Other reports from orthopaedic doctors also confirm that there are no associated risks with cracking your knuckles 鈥� as long as you aren鈥檛 causing pain or breaking fingers.
So, no need to knuckle under when you are warned that one day you will regret cracking your knuckles. That day is not likely to come.
