A modular catheter system including a sheath projecting distally from a delivery catheter having a main body module. An inner core module carrying a stent thereon, the inner core being axially movable through the main body of the delivery catheter and the delivery catheter sheath, a handle member supported by the main body of the delivery catheter, the handle member being selectively axially engageable with the inner core such that the handle member and the inner core move together in an axial direction when the handle member is engaged with the inner core; and an adjustment member supported by the main body, the adjustment member being configured such that rotation of the adjustment member causes the adjustment member to move axially along the main body by either axially sliding the handle member relative to the main body or by rotating the adjustment member.