In its preferred embodiment, a pair of shoulders are formed on the sides of a circular disk like head portion and a pair of spaced apart surfaces are formed on the socket portion which contact {HEAD ~ the shoulders} of {TAIL ~ the head portion} when the phalangeal component is at maximum flexion 
In its preferred embodiment , a pair of shoulders are formed on the sides of a circular disk like head portion and a pair of spaced apart surfaces are formed on the socket portion which contact { HEAD ~ the shoulders } of { TAIL ~ the head portion } when the phalangeal component is at maximum flexion
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