Premature cessation of longitudinal bone growth at a physeal (growth plate) site that does not fall under any other specifically classified location within the M89.1 subcategory.
Verified May 8, 2026 · 6 sources ↓
- Status
- Billable
- Chapter
- 13
- Related CPT
- 10
- Region
- Other
Documentation tips
What should appear in the chart to support M89.18.
Source · Editorial brief grounded in 6 cited references ↓
- Specify the exact skeletal site of the physeal arrest by anatomic name (e.g., 'left clavicular physis,' 'posterior iliac apophysis') so reviewers can confirm M89.18 is the most specific available code.
- Document the underlying etiology — prior Salter-Harris fracture, radiation, infection, or iatrogenic cause — because payer medical necessity review may require a causal link.
- Record any resulting deformity or limb length inequality with measurement, as these may support additional diagnosis codes and justify surgical intervention (e.g., epiphysiodesis).
- Confirm imaging findings (radiograph or MRI showing physeal bar, premature fusion, or growth asymmetry) are referenced in the note to support the diagnosis.
- Note the patient's skeletal maturity status (open vs. closed physis on imaging) — this affects treatment planning and may be queried during audit.
Related CPT procedures
Procedure codes commonly billed with M89.18. Linking the right diagnosis to the right procedure is what establishes medical necessity.
Source · CMS LCDs · AAOS specialty guidance · claims-pattern analysis
Common coding pitfalls
The recurring mistakes coders make with M89.18 and adjacent codes.
Source · Editorial brief grounded in CDC ICD-10-CM tabular guidance, AAOS coding references, and cited references ↓
- Defaulting to M89.18 when a site-specific M89.1x code exists — always verify M89.11 through M89.17 before assigning M89.18.
- Confusing physeal arrest (M89.1x) with a physeal fracture sequela (S-code with 7th character S) — physeal arrest is a disease-of-bone code, not an injury code, and carries no 7th-character extension.
- Using M89.18 for growth plate injuries that are still in active treatment; acute physeal injuries are coded with the appropriate Salter-Harris fracture code, not M89.1x.
- Omitting a secondary code for the resulting angular deformity or limb length discrepancy when it is the primary reason for the surgical encounter — both conditions should be coded.
Clinical context
Source · Editorial summary grounded in 6 cited references ↓
M89.18 captures physeal arrest occurring at skeletal sites not individually enumerated in the M89.1 subcategory — such as the pelvis, spine, ribs, clavicle, scapula, or small bones of the hands and feet when the specific site is not covered by a more precise M89.1x code. Physeal arrest, also termed growth plate arrest or epiphyseal arrest, occurs when the physis stops functioning prematurely, resulting in limb length discrepancy, angular deformity, or both. Common etiologies include prior physeal fracture (Salter-Harris injury), radiation exposure, infection, ischemia, or post-surgical disruption.
Use M89.18 only after confirming no site-specific M89.1 code applies. The M89.1 subcategory includes site-specific codes for the shoulder (M89.11), humerus (M89.12), forearm (M89.13), hand (M89.14), femur (M89.15), lower leg (M89.16), and ankle/foot (M89.17). If the affected physis corresponds to any of those sites, use the site-specific code. M89.18 is the correct choice when the physeal arrest is documented at the vertebral column, pelvis, ribs, sternum, clavicle, scapula, or a site genuinely not captured elsewhere.
This code is not laterality-specific; the ICD-10-CM tabular does not append a laterality character to M89.18. If the clinical note documents a bilateral arrest, you may need two instances of M89.18 or a narrative qualifier, but no separate bilateral code exists within this subcategory. Code also any associated deformity or limb length discrepancy (e.g., M21.7x) if separately documented and clinically relevant to the encounter.
Frequently asked questions
Source · Generated from the editorial pipeline, verified against 6 cited references ↓
01Which sites do NOT belong under M89.18?
02Does M89.18 require a 7th-character extension?
03Can M89.18 be used as a primary diagnosis for an epiphysiodesis procedure?
04How does M89.18 differ from a Salter-Harris fracture sequela code?
05Should I code the underlying cause separately when using M89.18?
06Is there a bilateral version of M89.18?
Sources & references
Editorial content was developed using the following public sources. Last verified May 8, 2026.
- 01CDC ICD-10-CM Tabular List 2026 (FY2026, effective Oct 1 2025)
- 02aapc.comhttps://www.aapc.com/codes/icd-10-codes/M89.18
- 03aapc.comhttps://www.aapc.com/codes/icd-10-codes/M89.1
- 04icd10data.comhttps://www.icd10data.com/ICD10CM/Codes/M00-M99/M86-M90/M89-/M89.18
- 05cms.govhttps://www.cms.gov/files/document/fy-2025-icd-10-cm-coding-guidelines.pdf
- 06aaos.orghttps://www.aaos.org/globalassets/quality-and-practice-resources/coding-and-reimbursement/resident-guide/resident-guide_icd10.pdf
Mira AI Scribe
Mira's AI scribe captures the affected skeletal site by name, laterality where applicable, imaging evidence of physeal bar or premature fusion, the suspected or confirmed etiology (e.g., prior Salter-Harris injury, radiation, infection), and any resultant deformity or limb length discrepancy with measurements. Capturing this detail prevents downgrade to the unspecified bone category and blocks audit queries about whether a more specific M89.1x site code was overlooked.
See how Mira captures M89.18 documentation