Table 1.

International classification of disease diagnosis codes used to identify degenerative sacroiliitis/sacroiliac joint disruption

ICD-9-CM code	Description
720.2	Sacroiliitis, not elsewhere classified, inflammation of sacroiliac joint NOS.
721.3a	Lumbosacral spondylosis without myelopathy. Lumbar or lumbosacral: arthritis, osteoarthritis, or spondylarthritis.
724.6	Disorders of sacrum. Ankylosis, lumbosacral or sacroiliac (joint). Instability, lumbosacral or sacroiliac (joint).
739.4	Nonallopathic lesions, not elsewhere classified in the sacral region: sacrococcygeal region or sacroiliac region.
846.9	Sprains and strains of sacroiliac region, unspecified site of sacroiliac region.
847.3	Sprains and strains of other and unspecified parts of back. Sacrum: sacrococcygeal (ligament).

Note:

^aICD-9-CM code 721.3 was excluded from the primary analysis and only included in the sensitivity analysis.

Abbreviation: NOS, not otherwise specified.