Injection devices and systems and methods for using them

A device for injecting a viscous injectate into tissue within a patient's body, the device comprising:

• an outer member comprising a proximal end, a distal end sized for introduction into a patient's body, and a lumen extending between the proximal end and the distal end;
• a needle tip extending distally beyond the distal end to a distal tip and including a passage communicating between the lumen and an outlet in the distal tip;
• a handle on the proximal end including a port communicating with the lumen and connectable to a source of viscous injectate for delivering the injectate through the port, the lumen, and the passage and out the outlet;
• and
• an inner member slidably disposed within the lumen, the inner member comprising a proximal end disposed adjacent the outer member proximal end and a distal end disposed within the lumen, the inner member having an outer profile smaller than an inner profile of the lumen such that the injectate passes through the lumen around the inner member, the inner member movable from a distal position wherein the inner member distal end is disposed immediately proximal to the passage during delivery of the injectate around the inner member to a proximal position in which the inner member distal end is directed proximally away from the passage after delivery of the injectate to prevent the injectate from expressing from the distal tip.