A retractor system can include a ring frame and a clamp. The ring frame can include a first ring segment and a second ring segment detachably joined to a first ring segment at a joint. The joint can be contained within a cross section of the ring frame that corresponds to a cutting plane perpendicular to an outer surface of the ring frame. The clamp can include an adjustment screw and a first set of jaws and a second set of jaws. The first set of jaws and second set of jaws can define a first aperture configured to receive the ring frame. Rotation of the adjustment screw in a tightening direction can cause the first set of jaws to engage the outer surface of the ring frame and apply a first clamping force to the outer surface of the ring frame received by the first aperture.