Table 1.

ICD-9 Diagnosis Codes and CPT Procedure Codes Searched.

Code	Diagnosis/Procedure
ICD-9-84.51	Insertion of interbody spinal fusion device
ICD-9-84.52	Insertion of recombinant bone morphogenetic protein (rhBMP)
CPT-22558	Anterior approach for lumbar fusion (anterior retroperitoneal exposure)

Abbreviations: ICD-9, International Classification of Diseases, Ninth Revision; CPT, Current Procedural Terminology.