biocompatible polyhydroxyalkanoate compositions with controlled degradation rates have been developed . in one embodiment , the polyhydroxyalkanoates contain additives to alter the degradation rates . in another embodiment , the polyhydroxyalkanoates are formed of mixtures of monomers or include pendant groups or modifications in their backbones to alter their degradation rates . in still another embodiment , the polyhydroxyalkanoates are chemically modified . methods for manufacturing the devices which increase porosity or exposed surface area can be used to alter degradability . for example , as demonstrated by the examples , porous polyhydroxyalkanoates can be made using methods that creates pores , voids , or interstitial spacing , such as an emulsion or spray drying technique , or which incorporate leachable or lyophilizable particles within the polymer . examples describe poly compositions including foams , coatings , meshes , and microparticles . as demonstrated by the examples , these polyhydroxyalkanoate compositions have extremely favorable mechanical properties , as well as are biocompatible and degrade within desirable time frames under physiological conditions . these polyhydroxyalkanoate materials provide a wider range of polyhydroxyalkanoate degradation rates than are currently available . methods for processing these materials , particularly for therapeutic , prophylactic or diagnostic applications , or into devices which can be implanted or injected , are also described .