2027 ICD-10-CM Diagnosis Code M99.18Subluxation complex (vertebral) of rib cage

ICD-10-CM Codes›M00–M99›M99›M99

ICD-10-CM M99.18
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

M99.18 is a billable ICD-10-CM diagnosis code for subluxation complex (vertebral) of rib cage. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 183 through 185, 963 through 965. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 19 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Biomechanical lesions.

Code Identity

ICD-10-CM Code
M99.18
Billable Status
Yes — Valid for Submission
Code Describes
Subluxation complex (vertebral) of rib cage
Short Description
Subluxation complex (vertebral) of rib cage
Same as the full description in the CMS dataset.
Parent Code
M99.1
Subluxation complex (vertebral)

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM99Biomechanical lesions, not elsewhere classified
CategoryM99Biomechanical lesions, not elsewhere classified
This CodeM99.18Subluxation complex (vertebral) of rib cage

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to M99.18: its own notes plus those printed at M99 and Chapter 13. A note printed at a category, block or chapter applies to every code under it.

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Chapter 13 (M00-M99) Diseases of the musculoskeletal system and connective tissue applies to 6,687 codes
  • arthropathic psoriasis (L40.5-)
  • certain conditions originating in the perinatal period (P04-P96)
  • certain infectious and parasitic diseases (A00-B99)
  • compartment syndrome (traumatic) (T79.A-)
  • complications of pregnancy, childbirth and the puerperium (O00-O9A)
  • congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • injury, poisoning and certain other consequences of external causes (S00-T88)
  • neoplasms (C00-D49)
  • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)

Notes

General instructions on how these codes are used.

From M99 Biomechanical lesions, not elsewhere classified applies to 91 codes
  • This category should not be used if the condition can be classified elsewhere.
From Chapter 13 (M00-M99) Diseases of the musculoskeletal system and connective tissue applies to 6,687 codes
  • Use an external cause code following the code for the musculoskeletal condition, if applicable, to identify the cause of the musculoskeletal condition

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name M99.18, its category, or a range that includes it.

Excludes1 1

These codes carry an Excludes1 note naming M99.18: they are not reported together with it, unless the two conditions are unrelated.

  • M43.5 Other recurrent vertebral dislocation
    biomechanical lesions NEC (M99.-) names M99.-, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR MUS012
Biomechanical lesions
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Dislocations

Dislocations are joint injuries that force the ends of your bones out of position. The cause is often a fall or a blow, sometimes from playing a contact sport. You can dislocate your ankles, knees, shoulders, hips, elbows and jaw. You can also dislocate your finger and toe joints.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert M99.18 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
839.61 Dislocat sternum-closed
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About M99.18Overview

What is the ICD-10 code for subluxation complex (vertebral) of rib cage?

The ICD-10-CM code for subluxation complex (vertebral) of rib cage is M99.18 (sometimes written as M9918). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is M99.18 (Subluxation complex (vertebral)) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report subluxation complex (vertebral) of rib cage on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does M99.18 group to?

When subluxation complex (vertebral) of rib cage is the principal diagnosis on an inpatient stay, it groups to MS-DRG 964, 965, 185, 183, 963, 184, with relative weights from 0.7712 to 2.6361 depending on complications. Higher weights mean higher Medicare reimbursement.

Is M99.18 a CC or MCC?

CMS lists M99.18 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 19 closely related codes in its exclusion list.

What is the ICD-9 equivalent of M99.18?

Under the General Equivalence Mappings, subluxation complex (vertebral) of rib cage converts to ICD-9-CM 839.61 (dislocat sternum-closed). The mapping is approximate, so confirm the match fits the documentation.