Abstract: A balloon implantation kit includes an inflatable biodegradable balloon configured to be implanted in a human body and a hydrogel composition. In some cases, the hydrogel composition is provided in a container configured to be introduced into the biodegradable balloon. For some applications, the biodegradable balloon includes a joint spacer for treatment of a joint of a human subject, such as a subacromial spacer, a glenohumeral spacer, or a spacer for another joint, such as a knee, hip, ankle, or hand (e.g., CMC1) joint. In these applications, the biodegradable balloon is configured to be inserted into a space of a joint of the human body, and is shaped to provide mechanical support to the joint until the biodegradable balloon resorbs into the human body. For other applications, the biodegradable balloon includes a soft tissue spacer.