A therapeutic delivery device comprises a layer of biodegradable material wound into a plurality of windings, the plurality of windings comprising an outermost winding defining an internal volume and winding pairs including a first winding pair and a second winding pair. A first therapeutic mass is incorporated in or on the layer the first winding pair and a second therapeutic mass is incorporated in or on the layer along the second winding pair. In one implementation, at least one volume of gas is captured within the internal volume and occupies at least 50% of the internal volume. In one implementation, the windings include perforations.