What happened to those who often "clicked" their fingers? Can they really get arthritis?

We often see that in martial arts movies, masters would crack their fingers before fighting to show that their fists are very "hard". In daily life, some people also like to bend their finger joints, especially those who work a lot or often type on the keyboard or write. Their fingers will feel sore, so the natural way to relax is to bend them.

However, some elders also say: "If you often crack your fingers, you will get arthritis in the future!" So, is this harmful to your fingers? Why does cracking your fingers make a "cracking" sound? Today, let's talk about whether cracking your fingers is harmful.

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Why do we hear a "cracking" sound when we snap our fingers?

First of all, except for fingers, all joints in the human body may make a "clicking" sound, which is clinically known as "joint popping". So, what exactly is joint popping?

Body movement is driven by many joints. The larger joints of the human body include the shoulder joint, elbow joint, wrist joint, hip joint, knee joint, etc. Joints are generally composed of articular surfaces, joint cavities, and joint capsules. Scientists generally believe that snapping is the sound of friction between articular surfaces, between cartilage pads and articular surfaces, between tendons and joint capsules, or the bursting of bubbles in joints.

Of course, there are some different opinions. In 2005, a Canadian research team performed dynamic MRI scans on the finger joints. They found that the finger joints are filled with synovial fluid. When the fingers are stretched, the synovial fluid will also change accordingly. During this process, gas will appear in the synovial fluid and form bubbles in the synovial fluid. The bubbles will exist until the fingers make a "click" sound. Therefore, they believe that the sound when bending the fingers is not caused by the bursting of bubbles, but is related to the formation of cavities in the joints.

When the joint is pulled apart, a black cavity can be seen forming inside the joint cavity. Image source: Reference 3

In addition, the experiment also found that when the joints are moving, the bones do not contact each other. Therefore, the sound produced by cracking fingers is not caused by bone friction.

Will you get arthritis if you often bend your fingers?

So, is frequent joint popping a disease? The answer is "no", because joint popping can be divided into physiological and pathological.

The characteristics of physiological joint popping are as follows:

1. It only occurs when the joint is stretched or flexed.

2. The joint must be still for a period of time before the popping occurs.

3. The sound is clear, single and non-repetitive.

4. There is no pain or discomfort when playing, but a sense of relaxation.

If the snapping does not meet any of the above criteria, it is pathological. In short, if the snapping is not accompanied by discomfort, it is a normal physical phenomenon, but if there is pain, swelling or other discomfort, you should seek medical attention in time.

There is also some interesting evidence that there is no correlation between finger cracking and arthritis.

Donald Unger, the winner of the Ig Nobel Prize, once experimented on himself. In order to prove that the accusations of his elders were groundless, Donald began a 50-year experiment: his right hand was used as a blank control and did not crack his fingers; his left hand was used as an experimental subject, and he continued to crack his fingers with similar intensity every day. From 1948 to 1998, Dr. Donald remained consistent. In 1998, the results of the experiment were unexpected. There was no obvious difference in the appearance, function, and X-ray images of Dr. Donald's hands, and they were both in a relatively healthy state.

Of course, the author believes that this experiment cannot fully explain the problem from the perspective of sample size or variable control. But no matter what, Professor Donald's persistent attitude towards scientific research is worth learning from.

In fact, there are more rigorous experiments that show that cracking your fingers does not cause arthritis.

In 2011, a study conducted a correlation experiment on 215 subjects between finger bending and hand osteoarthritis. The results showed that there was no correlation between finger bending and hand osteoarthritis in various joints. Arthritis is basically only related to factors such as family history of genetic diseases, heavy labor experience, and joint trauma. Donald's point of view is therefore strongly supported.

What will happen if you often snap your fingers?

Since Donald says that cracking your fingers is harmless, can we relax our muscles every day?

“It is foolish to talk about toxicity without considering the dosage.” Similarly, low-intensity and low-frequency finger cracking will not cause arthritis, but frequent and excessive finger cracking is dangerous.

In 2015, a literature report said that a 24-year-old man was hospitalized for long-term and frequent bending of his fingers. Examination revealed that the finger extensor tendon and dorsal retinaculum were damaged. When the finger joints were bent more than 50°, the finger joints would dislocate, and he eventually underwent surgery to recover.

When fingers are injured, especially when the ligaments are damaged and have not yet recovered, bending the fingers will aggravate the ligament damage, which may cause the fingers to become thicker and the finger joints to become unstable, which can easily lead to arthritis in the long run.

Therefore, there is no harm in cracking your fingers, but if you crack your fingers frequently for a long time, especially when the fingers themselves have primary diseases or injuries, cracking your fingers may become a bad habit that harms the health of your finger joints.

In addition, when the following pathological snapping occurs in the fingers, medical treatment is required in a timely manner:

1

Arthritis

If the finger popping is accompanied by joint pain, swelling, nodules around the joints, and finger stiffness, then this indicates that you may have arthritis.

2

Trigger finger

The medical name for "trigger finger" is stenosing tenosynovitis of the flexor tendons of the fingers. The essence of the disease is a chronic aseptic inflammatory reaction caused by repeated friction between the flexor tendons and the fibrous sheath of the flexor tendons at the metacarpophalangeal joints.

At first, you may feel pain in the palm and finger joints in the morning or after fatigue, find it difficult to hold things, and your fingers are difficult to straighten when bent, producing a snapping sound. In severe cases, the fingers may be fixed in the bent position and the other hand must be used to help the affected fingers to stretch. If the condition is delayed to the end, it may lead to joint contracture.

References

[1]UngerDL.Doesknucklecrackingleadtoarthritisofthefingers?[J].Arthritis&Rheumatology,1998,41(5):949-950.

[2]DeweberK,OlszewskiM,OrtolanoR.KnuckleCrackingandHandOsteoarthritis[J].TheJournaloftheAmericanBoardofFamilyMedicine,2011,24(2):169-174.

[3]GregoryN.Kawchuk,JeromeFryer,JacobL,etal.JaremkoReal-TimeVisualizationofJointCavitation, PLOSONE, 2015

[4]ClaudiaHammond.Doescrackingyourknucklescausearthritis[J]?BBCFuture,2012.09.18.

Planning and production

Author: Deng Ting, attending physician of orthopedics department of Changsha Third Hospital

Reviewer: Ji Gang, deputy chief physician of orthopedics, the First Hospital of Hebei Medical University