This is a plugin for Redmine which lets you annotate source code within the repository browser.
http://www.r-labs.org/wiki/r-labs/Code_Review
Copy the plugin directory into the plugins directory
Migrate plugin: rake redmine:plugins:migrate RAILS_ENV=production
Start Redmine
Add code review module into your project.
Go to code review setting tab in the project setting page and select tracker.
Go to "Roles and permissions" and add "Code Review" permissions to the roles you want to see/edit/manage code reviews.