Without seeing the Operative Procedure Report, diagnoses, etc., and not being an Orthopedic Oncologist, I am not certain what help I can give you, but I will try. As I understand Intercalary Endoprosthetic Femur Reconstruction, this is usually an extensive/radical procedure for bone cancers of the femoral shaft in which the shaft of the femur is removed, leaving as much of the proximal and distal femur as possible in place. The resected femur is then replaced by a "prosthetic femoral shaft" which is fitted in and attached to the proximal and distal femoral pieces to preserve the hip and knee joints. These procedures require a lot of preoperative planning to design and construct the prosthetic femoral shaft as they are not the type of thing that are kept in the average hospital supply room. These are not "Off the Shelf" devices. The only CPT Code I can find is 27365: Radical resection of tumor, femur or knee. This covers the "Excision" part of the procedure, but doesn't appear to say anything about filling in the bony defect by anything, let alone a prosthetic femoral shaft (the Intercalary Endoprosthetic Femur). To cover this you would probably need to use the 27599: Unlisted procedure, femur. You could also throw in Modifier 22 for Increase Procedural Services since this surgery goes well beyond the "norm."
I hope this helps you some.
Respectfully submitted, Alan Pechacek, M.D.
icd10orthocoder.com