Re: Does being double jointed mean you have 2 joints?

Jessica:  Good question!  It is a common misconception that "double 
jointed" means that a person has 2 joints & this is usually NOT true.  What 
it means most often is that the person has a higher amount of flexibility 
at their joints than a "normal" person.  This is usually due to ligaments 
being less taut or the dense regular connective tissue that they are made 
from is more "stretchy" than it should be.  Very infrequently does a person 
have a double joint cavity.  Several abnormal conditions, some that are 
serious genetic defects, give people this hyperlaxity condition.  One such 
defect is called "fragile X syndrome".  It is the second leading cause of 
mental retardation due to a genetic cause in the U.S. (Down syndrome is 
#1).  It is a very interesting example of a sex linked, single allelic 
condition.  These people are VERY flexible.  Don't get the idea that 
everyone who is very flexible has a defect!  It merely means that their 
joints are looser than the rest of us.  This can be helpful or harmful, 
depending on the degree of looseness and the activities to which their body 
is subjected.  Football players, for example, are tested for their joint 
tautness.  Idealy, they should not be so tight that they are prone to 
injury, particularly in the knee joints.  I hope this answer helps.  J. 
Bridger