Patent ID: 7695487

Claim:
An apparatus for separating tissue, comprising: a) a cannula tube having a lumen; b) an obturator rod having a distal end, the obturator rod being received in the lumen of the cannula tube; c) a guide having a distal end, the guide being movably received between the obturator rod and the cannula tube so that the distal end of the obturator rod engages the distal end of the guide when the obturator rod is moved in a proximal direction, the guide including: a guide tube having a distal end, the guide tube being disposed around the obturator rod, an end collar fixedly disposed at the distal end, a first collar fixedly disposed on the guide tube proximally of the end collar, and a guide collar slidably disposed on the guide tube; the guide collar having a proximal portion for engaging the first collar, the guide collar transitional from a first state defined by engagement of the proximal portion with a first region of the first collar having a first diameter to a second state defined by engagement of the proximal portion with a second region of the first collar having a second diameter different from the first diameter, wherein relative proximal movement between the obturator rod and the guide transitions the guide collar from the first state to the second state, wherein the guide collar is movable within the lumen of the cannula tube when in the second state; and d) the guide collar being expandable to engage the cannula tube when the guide collar is in the first state; and e) a balloon mounted on the obturator rod.