ACL REPAIR OF RIGHT KNEE; GRAFT FROM LEFT KNEE

Patient had a right knee ACL Repair [29888]

Graft was taken from the Left Knee, for which I billed 20924, using a modifier 59 on the claim

This procedure was denied per CCI Edit, stating I cannot override the edit
Even though this was a separate procedure, separate structure, am I able to appeal or is this final?

Thanks Orthos