Echolucent implants

A method for treating a patient comprising

• delivering a pharmaceutically acceptable implant through an applicator into the patient at a selected placement site, the implant comprising a flowable, hydrolytically biodegradable polymer composition, an osmotic agent, and a therapeutic agent, wherein the flowable, hydrolytically biodegradable polymer composition comprises a collection of covalently-crosslinked hydrolytically biodegradable hydrogel particles, a hydrogel precursor composition that reacts to form covalent bonds at physiological conditions with the product being covalently-crosslinked hydrolytically biodegradable hydrogel particles, or a combination thereof, wherein the implant at the selected placement site is echolucent, and wherein the therapeutic agent is released from the hydrogel particles at the placement site.