A surgical instrument comprises a first member including an inner surface that defines a cavity and an outer surface configured to space tissue. The first member includes a first locking surface. A second member is configured for disposal within the cavity and extends between a first end configured to penetrate tissue and a second end configured to generate a signal representative of a position of the second member. The second member includes a second locking surface. The members are disposable between a first orientation such that the locking surfaces are engaged to resist relative axial translation of the members and a second orientation such that the locking surfaces are disengaged and the second member is axially translatable relative to the first member. Systems and methods are disclosed.
