Abstract: The present invention relates to devices, systems, and methods for obtaining a quick diagnostic view of a cavity or joint of a patient and/or delivering a therapeutic treatment to that cavity or joint. The invention relates specifically to a cannula device that is sized for insertion into a patient for diagnosis or treatment in an office-based procedure and that has a securing mechanism that allows a scope or other instrument to be adjusted with respect to the cannula. Various optional features of the invention include a rotatable sleeve and an adapter for changing the working length of the cannula. The invention also relates to methods for performing an office-based diagnostic procedure and to kits for assisting the performance of such procedures.