Paranasal sinus apparatus is provided, including a hole-forming member configured to form a hole through a bone wall of a paranasal sinus of a subject. An implant is provided, having a proximal end and a distal end, and which is shaped to define a lumen. The implant is couplable to the hole-forming member, and is securable to the wall and extendable through the hole, such that the proximal end is disposed external to the paranasal sinus and the distal end is disposed within the paranasal sinus. The implant includes a biodegradable material. Other applications are also described.