hallo!
das mit dem fingerknacken wurde am 20.12. schonmal allgemein gefragt-siehe die unten angefügten wissenschaftlichen untersuchungen dazu.
was vermutlich passiert (und was ich persönlich für die beste erklärung halte):
durch den hohen druck im gelenk entsteht ein übermässig grosser unterdruck im gelenk. dadurch wird die gelenkkapsel „eingesaugt“. wenn man nun bewegt dann wird der innenwiderstand mit gewalt überwunden, die kapsel „schnappt“ zurück und es löst sich eine gewisse menge gas aus der gelenkflüssigkeit.
ach ja-und irgendwas davon macht dann „plopp“.
schädlich? nicht wenn man es nur manchmal macht. was man gefunden hat ist eine abnahme der handkraft wenn man es ständig macht. würde aber auf dich nicht zutreffen weil es ja nur zwei gelenke betrifft.
was kann man machen: daumenbelastende tätigkeiten abstellen. machst du irgendwas wobei du den daumen täglich einsetzt? nicht so sachen wie per anhalter fahren-aber druck mit dem daumen ausübst?
wenn das so ist dann versuchen die ausführung zu ändern.
tschüss
matthias
hier noch ein paar wissenschaftliche untersuchungen zum thema:
- Brodeur R.
The audible release associated with joint manipulation.
Journal of Manipulative and Physiological Therapeutics, 1995 Mar-Apr,
18(3):155-64.
Abstract: OBJECTIVE: The objective of this paper is to review the literature on
the audible release associated with manipulation. DATA SOURCES:
Bibliographic information in pertinent articles and papers located in the
MEDLINE database containing the keywords joint, joints, cartilage, crack,
cracking, cavitation, crepitus and noise. STUDY SELECTION: All articles
relevant to the objectives were selected. DATA EXTRACTION: All available
data was used. DATA SYNTHESIS: The audible release is caused by a
cavitation process whereby a sudden decrease in intracapsular pressure
causes dissolved gasses in the synovial fluid to be released into the joint
cavity. Once a joint undergoes cavitation, the force-displacement curve
changes and the range of motion of the joint increases. The gasses released
from the synovial fluid make up about 15% of the joint volume and consist
of approximately 80% carbon dioxide. Habitual joint cracking does not
correlate with arthritic changes, but does correlate with loss of grip
strength and soft-tissue swelling. During the „crack“ associated with a
joint manipulation, there is a sudden joint distraction that occurs in less
time than that required to complete the stretch reflexes of periarticular
muscles. Theories on the cavitation mechanism were reviewed and new
information on the cavitation process is introduced. In this paper, it is
proposed that the cavitation process is generated by an elastic recoil of
the synovial capsule as it „snaps back“ from the capsule/synovial fluid
interface. CONCLUSIONS: Because the sudden joint distraction during a
manipulation occurs in a shorter time period than that required to complete
the stretch reflexes of the periarticular muscles, there is likely to be a
high impulse acting on the ligaments and muscles associated with the joint.
This is an important conclusion, because others have proposed that reflex
actions from high threshold periarticular receptors are associated with the
many beneficial results of manipulation. This suggests that the cavitation
process provides a simple means for initiating the reflex actions and that
without the cavitation process, it would be difficult to generate the
forces in the appropriate tissue without causing muscular damage.
[2] Castellanos J. Axelrod D.
Effect of habitual knuckle cracking on hand function.
Annals of the Rheumatic Diseases. 49(5):308-9, 1990
Discussion
The development of arthritis of the hand as a result of habitual knuckle-cracking has been considered an old wives’ tale. Swezey reviewed 28 nursing home patients who could recall whether or not they had cracked their knuckles. Among these patients, a relationship between knuckle cracking and arthritis could not be found[1]. Indeed, metacarpophalangeal osteophytes were found in patients who had not been habitual knuckle crackers.
Yet a bioengineering study of cracking joints suggested the potential for significant joint damage.[2] When tension is applied to the joint, cavitation occurs within the synovial fluid. This creates an unstable condition as the pressure within the bubble is lower than that of the surrounding fluid. Because the joint separation occurs at a high rate the net flow of synovial fluid is toward the low pressure regions, with a collapse of the vapour phase of the cavity. There is a release of vibratory energy, which may be responsible for the cracking sound.
It is this phenomenon which is responsible for the erosion of ship propellers and the blades of hydraulic turbines.[3]
Given the potential damage caused by this cavitation phenomenon, one might expect habitual knuckle cracking to cause some decrement in hand function, if not accelerate the onset of osteoarthritis of the hand.
Of the 300 patients studied, 74 admitted to habitual knuckle cracking for 35 (18) years. Their sex distribution was similar to that of those denying knuckle cracking. Those patients who were habitual knuckle crackers were more likely to have swelling of the hand and lower grip strength (table 2). Other factors which might influence hand function, such as carpal tunnel syndrome, contractures, surgery or trauma to the hand, and the presence of Heberden’s or Beouchard’s nodes, were equally present in both patient groups. Habitual knuckle crackers however, were more likely to be manual labourers with higher incomes (tables 1 and 2).
Although the cause of habitual knuckle cracking was not considered in this study, patients admitting to it were more likely to bite their nails, smoke, and drink alcohol, as were members of their families (table 2).
This study suggests that although habitual knuckle cracking does not relate to osteoarthritis of the hand, it may relate to decreased hand function. Therefore, habitual knuckle cracking should be discouraged.
[3] Simkin PA.
Habitual knuckle cracking and hand function.
Annals of the Rheumatic Diseases. 49(11):957, 1990
SIR: In a recent survey Castellanos and Axelrod evaluated 300 consecutive outpatients at Mount Carmel Mercy Hospital to determine whether habitual knuckle cracking is a risk factor for hand dysfunction. They found no relation with osteoarthritis, but noted that ‚knuckle crackers were more likely to have hand swelling and lower grip strength‘ and concluded that 'habitual knuckle cracking results in functional hand impairment. I believe they have not established cause and effect in these interesting correlations.
Not everyone can crack their knuckles. Some do so with ease, whereas others are quite incapable of performing this feat. No one has determined how the joints of these groups differ. It is quite possible, for instance, that metacarpophalangeal joint laxity may both facilitate knuckle cracking and impair hand function. As this hypothesis implies that hand swelling and diminished grip occur secondary to articular structure rather than abuse, it may be that nervous citizens of Detroit can continue to crack their knuckles without fear of injury.
‚Will cracking my knuckles hurt my hands?‘ remains a common gambit when a rheumatologist is identified as such among new acquaintances striving to make conversation. I still believe that the answer to this question is no, but perhaps it is time that we really found out.
[4] Watson P. Hamilton A. Mollan R.
Habitual joint cracking and radiological damage.
BMJ. 299(6715):1566, 1989
A 25 year old Malaysian man who habitually elicited cracking sounds from many of his joints was investigated during a study of joint cracking. He had no symptoms or obvious abnormalities of his joints, but a radiograph of his right hand showed ligamentous ossification on the ulnar side of his third metacarpophalangeal joint and chondrocalcinosis in the first and fourth metacarpophalangeal joints (figure). There was no evidence of osteoarthritis.
Distraction of the articular surfaces during finger pulling lowers the pressure of the articular fluid. When the vapour pressure is reached the fluid evaporates, giving a cracking sound and forming an intra-articular bubble. Previous studies have reached conflicting conclusions about the radiological changes found in habitual finger cracking,[1,2], but we suggest that excessive joint cracking caused the changes seen in this subject, who had no signs of any other underlying disease.
)
))