A surgical instrument for performing surgery includes a housing defining an axial bore. A lock is slidably disposed in the transverse bore to engage and disengage a tube adaptor. A latch extends from the lock to move the latch into and out of the axial bore. The lock and latch allow for interchangeability of tip assemblies inserted into the surgical instrument. A first and second handle are pivotally attached to the housing. A first ratchet member is rotatably attached to the first handle and includes serrated teeth. A second ratchet member extends from the second handle. The second ratchet member including a finger for engagement with the serrated tooth to prevent movement of said first handle relative to the second handle. The first ratchet member is rotatable about the rotational axis to disengage from the second ratchet member and allow the first handle to move relative to the second handle.