Hi dg
The information collected by RIDDOR is passed on to your local council but also used for statistical purposes. If the authority believe this injury to be a result of unsafe working practices they may give you a visit (usually at the particular site it happened) but only if its work related. When the employee "allegedly" hurt her back was an accident form filled in? I cant stress how important this document is, it needs to include details of what happened and any witnesses and you as the most senior person should have been notified as soon as possible after it happened. If there were witnesses get statements from them. Has the staff member actually said she did this at work?? doesnt say in your post. If she has get all the information about what allegedly happened from her, write it down and get her to sign it. Review your current working practices at the site it happened against her statement and your own method statements. Look for differences between them. Do you have risk assessments in place and kept on site? if so do you get your staff to read them and sign/initial to say they have?
Keep all the info together and file away along with the notification hse will send you, keep them for at least 3 years.
Theres no need to worry about it, as long as you have your paperwork in order and you have done everything possible to ensure the safety of your staff. Most cases are a result in the staff member doing tasks incorrectly.
Regards
Dave