Patent ID: 8062293

Claim:
A strut for coupling two ring elements of an external fixator, comprising a rod, a sleeve coupled to the rod having inner and outer spherical portions; a ring insert having a wedge surface for insertion into a hole in a ring element; a blocking element having a wedge surface being complementary with the wedge surface of the ring insert and a spherical socket, wherein the outer spherical portion of the sleeve engages the complementary spherical socket of the blocking element, a ball nut having a spherical surface for engaging the inner spherical portion of the sleeve; a connection element having an end portion for engaging the ball nut; wherein the ring insert and the blocking element have a combined circumferential surface being adapted to be introduced into the hole of the external fixator ring element, wherein the complementary wedge surfaces allowing a relative axial displacement of ring insert and blocking element one against the other causes a radial expansion to enlarge the diameter of the combined circumferential surface for locking the ring element and blocking element inside the ring hole, wherein the connection element extends through the sleeve, the blocking element and ring insert into the ball nut and wherein the connection element and ball nut are arranged to activate the radial expansion upon an axial displacement therebetween.