Any authentication system using biometrics needs to have a fail-safe to be activated when the biometric factor fails (e.g., injury). This should only be skipped if you are using the system for flagging purposes only. Depending on the design of your solution, there are multiple options on how to proceed.
If the injury is transitory, the failsafe you have should be able to deal with the issue.
If the injury is permanent (underlined by a consistent failure of the biometric factor over a longer period of time), you can re-enroll the user. It is the same process as resetting your password. The existing typing biometric profile will be deleted and a new one will be created. The user will have to resubmit typing patterns for enrollment.
For more information, read our “FAQs – If your typing pattern changes, can you still be authenticated?” blog post.