ICD-10-CM 2027
ICD-10 code for intervertebral annular fibrosis defect
Unspecified thoracic, thoracolumbar and lumbosacral intervertebral disc disorder
From the official ICD-10-CM alphabetic index entry “Defect, defective › intervertebral annular fibrosis”. Page updated September 29, 2026.
About coding intervertebral annular fibrosis defect
The ICD-10-CM code for intervertebral annular fibrosis defect is M51.9 (Unspecified thoracic, thoracolumbar and lumbosacral intervertebral disc disorder). The official index lists 6 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on M51.9.
Within M51, choose M51.9 (Unspecified thoracic, thoracolumbar and lumbosacral intervertebral disc disorder) only when documentation doesn't support a more specific option: thoracic, thoracolumbar and lumbosacral intervertebral disc disorders with myelopathy (M51.0), thoracic, thoracolumbar and lumbosacral intervertebral disc disorders with radiculopathy (M51.1), other thoracic, thoracolumbar and lumbosacral intervertebral disc displacement (M51.2), other thoracic, thoracolumbar and lumbosacral intervertebral disc degeneration (M51.3), Schmorl's nodes (M51.4), other thoracic, thoracolumbar and lumbosacral intervertebral disc disorders (M51.8) and other lumbar and lumbosacral annulus fibrosus disc defects (M51.A).
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
In MS-DRG v44.0, it is part of the grouping logic for DRG 551 (Medical Back Problems with MCC, relative weight 1.6358) and DRG 552 (Medical Back Problems without MCC, relative weight 0.9584), in MDC 08 (Diseases and Disorders of the Musculoskeletal System and Connective Tissue), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
More specific intervertebral annular fibrosis defect codes (official index)
- lumbar M51.A0 — Intervertebral annulus fibrosus defect, lumbar region, unspecified size
- large M51.A2 — Intervertebral annulus fibrosus defect, large, lumbar region
- small M51.A1 — Intervertebral annulus fibrosus defect, small, lumbar region
- lumbosacral M51.A3 — Intervertebral annulus fibrosus defect, lumbosacral region, unspecified size
- large M51.A5 — Intervertebral annulus fibrosus defect, large, lumbosacral region
- small M51.A4 — Intervertebral annulus fibrosus defect, small, lumbosacral region
Common questions about intervertebral annular fibrosis defect ICD-10 codes
What is the ICD-10 code for intervertebral annular fibrosis defect?
- M51.9 — Unspecified thoracic, thoracolumbar and lumbosacral intervertebral disc disorder. More specific codes apply when the documentation supports them: M51.A0, M51.A2, M51.A1, M51.A3 and others below.
What is the ICD-10 code for lumbar intervertebral annular fibrosis defect?
- M51.A0 — Intervertebral annulus fibrosus defect, lumbar region, unspecified size.
What is the ICD-10 code for lumbosacral intervertebral annular fibrosis defect?
- M51.A3 — Intervertebral annulus fibrosus defect, lumbosacral region, unspecified size.
Is M51.9 billable?
- Yes. M51.9 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can M51.9 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict M51.9 as a principal diagnosis.
Is M51.9 a CC or MCC?
- No. M51.9 is neither a CC nor an MCC under MS-DRG v44.0.