In one form, an expandable cannula assembly for use in percutaneous surgical procedures includes an elongate body extending along a longitudinal axis between a first end and a second end. The elongate body includes a pair of elongate members that cooperate to define a working channel extending between a proximal end and a distal end and being expandable from a first, unexpanded configuration to a second, expanded configuration. The elongate members are displaceable away from one another along the longitudinal axis from the proximal end to the distal end of the working channel in order to expand the working channel from the first configuration to the second configuration. In one aspect, the elongate members engage with one another to lock the working channel in the second configuration and prevent movement of the elongate members toward one another. However, in other embodiments, different forms and applications are envisioned.