• So far there have been various theories about the origin of noise.
• Researchers observed the process in the magnetic resonance tomograph.
• There is no indication of whether the cracking is bad or good for the joints.

The cracking noise when pulling apart of fingers formed according to a study by the formation of a cavity in the joint.

Finger in the magnetic resonance tomograph

In the investigation, Greg Kawchuk’s team from the University of Alberta in Edmonton, Canada, took a closer look at a man’s metacarpophalangeal joints in an MRI scanner. The scientists present their results in the journal “PLOS ONE” .

Is there a threat to health?

Some people can crack their joints when they pull their fingers apart. There is currently no evidence as to whether this phenomenon is bad or good for the joints. “So far, no one has ever been able to prove that this  cracking is harmful to health in the long term,” says Professor Jörg van Schoonhoven from the Clinic for Hand Surgery at the Rhön Clinic in Bad Neustadt an der Saale.

Different theories

For a long time there have been various theories about where the popping sound when clicking your fingers comes from. Some scientists suspected that the crackling sound was caused by a bursting bubble in the joint space.

Other researchers hypothesized that the sound is caused by the flapping of ligaments.

Another explanation for the origin of the cracking is what is known as tribonucleation: a mechanism in which the movement of surfaces creates gas bubbles in a liquid.

Study author as guinea pig

To date, there has not been any direct experimental evidence that solidly supports any of the theories. Kawchuk’s researchers wanted to change that. 

For their study, the scientists needed someone who had the ability to crack their metatarsophalangeal joints on request. These joints connect the bones of the metacarpus to the base members of the fingers. The choice fell on Jerome Fryer, one of the study authors.

Pull until it cracks

In the experiment, the researchers examined each finger of the test subject in isolation in a special magnetic resonance tomograph, with which movement sequences can be recorded.

The finger was attached to a kind of tube that was connected to a cable at the other end. Then the cord was pulled until Fryer’s fingers cracked. The entire process in the joint was recorded with an MRI scanner.

Is a cavity the cause?

Shortly before the cracking could be heard, the researchers were able to observe the formation of a cavity in the images.

The scientists therefore assume that tribonucleation has taken place in the joint: “It is a bit as if a vacuum is being formed,” explains Kawchuk in a communication on the study. “If the joint surfaces suddenly separate, there is no longer any liquid left to fill the increasing joint volume. This creates a cavity.” The noise is generated by this event. 

“It is interesting to know what acoustic phenomenon is behind the cracking of the fingers,” said the hand surgeon van Schoonhoven. However, by including only one person in their study, Kawchuk’s researchers would be able to explain the phenomenon only for that person. “The experimental setup does not allow any generalized statements,” said van Schoonhoven.

• Osteoarthritis results from wear and tear on bones and joint capsules.
• Five million Germans suffer from the consequences.
• Briefly explained: which osteoarthritis treatment helps whom?

If the joints hurt, it is usually osteoarthritis : it is the most common of all joint diseases. About five million Germans suffer from it. Osteoarthritis occurs when bones, ligaments, tendons and joint capsules wear out.

This is important to differentiate the disease from rheumatoid arthritis. Inflammation is the cause here.

This is important for osteoarthritis treatment

“Arthrosis is a disease that runs in waves,” explains Johannes Flechtenmacher, President of the Professional Association of Orthopedists and Trauma Surgeons. Less painful phases alternate with those that torment those affected.

The aim of the treatment is to relieve the pain on the one hand and to maintain or restore the ability to move on the other.

Osteoarthritis needs combination treatments

Ideally, the doctor combines non-drug treatments such as physiotherapy, nutritional recommendations, and hot or cold applications with medication. These are mainly used in the acute pain phase.

“In the less painful episodes, patients should try to avoid medication,” explains Flechtenmacher. In principle, movement in particular is an important component of therapy. His motto: “Move a lot, load little.”

Five osteoarthritis treatments put to the test:

1. NSAIDs: cortisone-free pain relievers

This is how the drug works: The non-steroidal anti-inflammatory drugs (NSAIDs) are the classic all-rounders in pain relief. They have both anti-inflammatory and analgesic effects, but do not contain cortisone.

Medicines include ibuprofen, diclofenac, or naproxen. They block two important enzymes that play a role in the sensation of pain: Cyclooxygenase (COX) isoenzymes I and II.

The so-called Cox II inhibitors are therefore well suited to treat acute joint pain associated with osteoarthritis.

NSAIDs also have an antipyretic effect.

Side effects: Gastrointestinal complaints and an increased risk of cardiovascular diseases are among the risks of NSAIDs. “That is why it is particularly important to tailor the osteoarthritis treatment to the patient,” explains orthopedist Flechtenmacher.

For example, ibuprofen is not suitable for patients with kidney problems, and diclofenac hits the liver. Both drugs also have a negative effect on the cardiovascular system. Naproxin is therefore better suited for heart disease patients with osteoarthritis.

2. Opioids

This is how the drug works: Opioids are effective remedies that are used against severe joint pain. By attacking the opioid receptors, they prevent pain from developing and being transmitted.

Tramadol is one of the morphine-like drugs. “Morphines are not suitable for treating acute phases of pain in osteoarthritis,” says Flechtenmacher. This is especially true for plasters. Morphine should only be used for chronic treatment if no other therapy is helping the patient.

Side effects: Many sufferers suffer from the exhaustion caused by morphine. Especially in older people, opioids aggravate many age problems. These include, for example, constipation and dizziness. This also increases the risk of frail patients falling.

3. Hyaluronic acid

In addition to drugs that directly combat pain, there are active ingredients that intervene in the mechanism of the disease. A typical representative is hyluronic acid.

This is how the drug works: Doctors inject hyaluronic acid into the joint to treat osteoarthritis. That’s the only way it works. “In contrast, it is pointless in tablet form, as is sometimes offered,” explains Flechtenmacher. Only in the joint does the drug help the knees or fingers move more smoothly.

With regard to evidence-based studies, hyaluronic acid should be viewed critically, adds the doctor. For example, the relief of osteoarthritis on knock knees or bow legs, where it is biomechanically induced, works less well than on straight legs.

Side effects: As a rule, osteoarthritis patients tolerate hyaluronic acid very well. Since it is injected directly into the joint, there is the usual risk of infection from the method.

4. Natural medicine

This is how the treatment works: Natural active ingredients such as nettle leaves, willow bark or devil’s claw should also relieve pain. The latter contains, among other things, harpagoside. Similar to the non-steroidal anti-inflammatory drugs, they are supposed to inhibit the formation of the pain messenger prostaglandin.

“So far, however, nothing has been identified in evidence-based studies that proves the effectiveness of the natural active ingredients,” explains Flechtenmacher.

Side effects: They are dependent on the natural medicine product. The instruction leaflet of the devil’s claw, for example, warns of possible gastrointestinal complaints such as diarrhea, nausea, flatulence, vomiting as well as dizziness and headaches or rashes.

5. Acupuncture

This is how the treatment works: As with natural active ingredients, evidence of how acupuncture works for osteoarthritis has not yet been provided in scientific studies.

On the contrary. An Australian study looked at the effects of acupuncture. The results published in the “JAMA” magazine showed: Acupuncture with needles or laser has no relevant effect on pain and function in patients over 50 with knee osteoarthritis and moderate or severe chronic pain.

However, acupuncture helps some osteoarthritis sufferers. Johannes Flechtenmacher, for example, relies on the alternative form of treatment

• light and irregular pain
• when many illnesses in the affected person rule out other drugs.

In addition, there are many patients who benefit from the doctor’s attention and empathy alone.

Side effects: The symptoms can get worse at first, writes the German Pain Society on acupuncture . And adds: “Occasionally there are slight bruises or bruises, and brief circulatory reactions can also occur during acupuncture treatment.”

In any case, those affected should not treat their joint pain independently, but should always have it checked out by a specialist.

• If you want to do something about osteoarthritis, you should exercise.
• With these sports you can prevent.
• At the same time, those affected can still practice many sports.

Anyone who hurts movements in their knees, shoulders or ankles usually suffers from osteoarthritis. It is the most common joint disease. At least five million Germans suffer from it. Experts even speak of 35 million people affected in Germany for early forms of osteoarthritis.

From the age of 30, the risk increases linearly. Among those over the age of 60, 50 percent of women and a third of men suffer from osteoarthritis.

Strictly speaking, however, everyone would get osteoarthritis, says Karl-Dieter Heller, chief physician at the Orthopedic Clinic Duchess Elisabeth Hospital. From the age of 40 at the latest, arthritic changes appear in the X-ray. Osteoarthritis occurs when bones, ligaments, tendons and joint capsules wear out.

• The body’s own stem cells have a positive effect on osteoarthritis-related inflammation in the knee.
• A study now wants to clarify whether they actually build up permanent cartilage.
• A transplant can repair minor cartilage damage in young patients.

After a certain age, signs of wear and tear become noticeable in the knee . After the age of 30, the risk increases linearly. The painful, inflammatory breakdown of cartilage in the operating room and with an artificial knee ends 150,000 times a year. Then smooth metal has to replace the cartilage layer, which allows round, painless movements in a healthy knee.

The idea frightens many people suffering from osteoarthritis. They hope for new methods to rebuild lost cartilage: stem cells should help.

Belly fat provides the best stem cell material

The doctor uses the patient’s belly fat as a starting material. The idea behind it: stem cells can be obtained particularly easily and in relatively large numbers from vascular fat tissue. Injected at the location of the defect, they learn from the microenvironment into which cell type they should develop.

According to this principle, the doctor and stem cell researcher Eckhard Alt uses the undifferentiated cells : Stem cells from the patient’s fat tissue are processed in the operating room within an hour and injected into the patient where he needs them – for example into the osteoarthritis knee.

The founder of the “Interdisciplinary Stem Cells Research Center” in Houston and a private clinic in Munich sees stem cells as the future therapy for chronic inflammatory diseases of the musculoskeletal system – among other things.

The cell extract in the knee does not guarantee success

Some orthopedic practices that offer the procedure honestly state that it is a not generally recognized attempt at healing with no guarantee of success. Rather, it is a final experimental attempt to remedy knee problems without a joint replacement.

“In this so-called ‘point-of-care’ application, a cell extract is injected that not only consists of stem cells,” explains Oliver Pullig from the Fraunhofer Translational Center for Regenerative Medicine in Würzburg. How many stem cells that are supposed to develop into cartilage material actually get into the knee is just as little regulated as the preparation of the suctioned off belly fat.

Stem cells instead of knee prostheses

A Europe-wide study is currently looking for scientific evidence of the anti-osteoarthritis potential of the body’s own stem cells.

A small one with six patients in Würzburg and twelve in Montpellier, France, led to success in 2013: Almost all participants canceled their previously unavoidable operation for a knee prosthesis. “Your complaints had improved throughout,” explains Oliver Pullig. “A reconstruction of cartilage was unlikely with such a large damage.”

The follow-up study that has just begun with 153 participants at ten European locations therefore fulfills a requirement that the German study director Ulrich Nöth from the Evangelical Forest Hospital Berlin-Spandau formulated back then: Stem cell therapy is best suited for patients with middle and middle-aged osteoarthritis. You are no longer eligible for a cartilage transplant, but you are too young to have an artificial joint.

New cartilage from stem cells? A study should show it

Like the pilot study, the ADIPOA2 study uses so-called mesenchymal stem cells from the abdominal fat of each subject. These precursor cells of the connective tissue have the ability to develop into cartilage, bone or fat cells.

Biologist Oliver Pullig explains: “We take 100 milliliters of belly fat from each participant. The stem cells obtained from this are multiplied millions of times in special laboratories. That takes a good two weeks. 51 patients then receive two million of these pure stem cells injected into the joint, 51 patients receive an injection with 10 million cells and 51 patients receive a placebo. “

Results should be available by the end of 2018, and thus scientific proof of whether stem cells fulfill the hope of permanently building cartilage. The scientist is optimistic: “If successful, the therapy with stem cells as a drug could be ready for the market at the next study level. It doesn’t take five years. “

Cartilage transplant only helps to a limited extent

Another method to restore lost cartilage is transplantation, which has been tried and tested for 20 years. So far, however, it has only been successful in the case of centimeter damage in an otherwise intact knee. The operation is laborious and the healing process long.

In the first keyhole surgery, the doctor removes a small piece of healthy cartilage, hardly larger than a grain of rice. These cartilage cells are propagated in the laboratory in three to four weeks. In a second operation, the surgeon places these cells or the cartilage patch on the defective area in the knee.

After that, the knee must not be subjected to any load for six weeks, then only lightly for another six weeks. Only after a year is the joint stable enough for sport to be possible.

Cartilage from the laboratory is expensive

The transplant is only suitable for younger knee patients whose cartilage and joints are free from osteoarthritis. If this therapy is successful, it can prevent further cartilage damage and a later threatened knee prosthesis.

Then, in the long term, the costs of several thousand euros for cells grown in a laboratory will pay off.

Hyaluronic acid can at least relieve pain

If these methods are out of the question, another remedy can help: synthetic hyaluronic acid is often misunderstood as a substance for building up cartilage. However, it cannot produce worn cartilage, but serves as a lubricant and for joint care.

Orthopedic surgeons inject the moisture-retaining gel three to five times at weekly intervals. Hyaluronic acid relieves pain and promotes mobility – permanently for some patients, at least for a year or two for others. Then the treatment can be repeated.

If you rest, you rust. There is a lot of truth in this banal wisdom – especially when it comes to muscles and joints. Those who are young have often integrated sport into everyday life as a matter of course. But with age, people often give up. That is fatal.

Because it is precisely at the age of three that there is a significant drop in performance, explains Karl-Dieter Heller, chief physician at the Orthopedic Clinic Duchess Elisabeth Hospital. The muscles begin to break down. Right here it is called to hold against.