Biodegradable polymer composition

A flowable composition containing a biocompatible, biodegradable, branched thermoplastic polymer is used to form solid matrices such as implants and controlled-release, drug-compositions in a body. The flowable composition with or without bioactive agent can be administered by syringe and needle to form in situ a solid matrix. Alternatively, the flowable composition can be used to form ex vivo solid biodegradable matrices such as articles, implants and devices. The articles implants and the like can then used as solid fasteners, prosthetic devices, and controlled drug compositions.