What to do if I have been diagnosed with femoral nerve damage after a total hip replacement about 6 months ago?

It would be advisable to be examined by another doctor, who may be able to determine whether or not your femoral nerve damage resulted from the hip replacement surgery.  If that doctor writes a report supporting that conclusion, this will strengthen your claim of medical malpractice.  Medical malpractice is negligence.  Negligence is the failure to exercise due care (that degree of care that a reasonable medical practitioner in the community would have exercised under the same or similar circumstances to prevent foreseeable harm).

If the second doctor's report supports a malpractice claim, prior to filing a lawsuit it may be possible to settle the case with the surgeon's malpractice insurance carrier.  Your claim filed with the malpractice insurance carrier should include your medical bills, medical reports (especially the medical report from the second doctor) and documentation of wage loss.  Compensation for the medical bills is straight reimbursement .  The medical reports will document the nature and extent of your injury and will be used to determine compensation for pain and suffering which is an amount in addition to the medical bills.  Compensation for wage loss is straight reimbursement.  If the case is settled with the surgeon's malpractice insurance carrier, NO lawsuit is filed.  If you are dissatisfied with settlement offers from the malpractice insurance carrier, reject the settlement offers and file a lawsuit for negligence against the surgeon.  If the case is NOT settled with the surgeon's malpractice insurance carrier, you will need to file your lawsuit for negligence against the surgeon prior to the expiration of the applicable statute of limitations or you will lose your rights forever in the matter.