2027 ICD-10-CM Diagnosis Code M84.649KPathological fracture in other disease, unspecified hand, subsequent encounter for fracture with nonunion

ICD-10-CM Codes›M00–M99›M80-M85›M84

ICD-10-CM M84.649K
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

M84.649K is a billable ICD-10-CM diagnosis code for pathological fracture in other disease, unspecified hand, subsequent encounter for fracture with nonunion. The 7th character K means subsequent encounter for fracture with nonunion. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 564 through 566. 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 5,561 closely related codes. The code is flagged as an unspecified code, since codes identifying laterality exist in the same family. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Pathological fracture, subsequent encounter.

Code Identity

ICD-10-CM Code
M84.649K
Billable Status
Yes — Valid for Submission
Code Describes
Pathological fracture in other disease, unspecified hand, subsequent encounter for fracture with nonunion
Short Description
Path fx in oth disease, unsp hand, subs for fx w nonunion
Parent Code
M84.649
Pathological fracture in other disease, unspecified hand

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM80-M85Disorders of bone density and structure
CategoryM84Disorder of continuity of bone
This CodeM84.649KPathological fracture in other disease, unspecified hand, subsequent encounter for fracture with nonunion

Code EditsBilling

Medicare Code Editor checks that affect claim validity for M84.649K.

Unspecified codes
Unspecified codes exist in the ICD-10-CM classification for circumstances when documentation in the medical record does not provide the level of detail needed to support reporting a more specific code. However, in the inpatient setting, there should generally be very limited and rare circumstances for which the laterality (right, left, bilateral) of a condition is unable to be documented and reported. The following pages contain the list of unspecified ICD-10-CM diagnosis codes for which there is a more specific code to identify laterality (right, left, bilateral) within that code family.

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to M84.649K: its own notes plus those printed at M84.6, M84, and Chapter 13. A note printed at a category, block or chapter applies to every code under it.

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From M84.6 Pathological fracture in other disease applies to 192 codes
  • pathological fracture in osteoporosis (M80.-)

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 M84 Disorder of continuity of bone applies to 928 codes
  • traumatic fracture of bone-see fracture, by site
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)

Code Also

A second code may be needed to fully describe the condition; the note gives no sequencing direction.

From M84.6 Pathological fracture in other disease applies to 192 codes
  • underlying condition

Notes

General instructions on how these codes are used.

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

7th Character

Every code in the category takes a 7th character from the listed values, with the placeholder X filling any empty positions before it.

From M84.6 Pathological fracture in other disease applies to 192 codes
  • The appropriate 7th character is to be added to each code from subcategory M84.6:
Values for category M84.6 Pathological Fracture Encounter
  • Ainitial encounter for fracture
  • Dsubsequent encounter for fracture with routine healing
  • Gsubsequent encounter for fracture with delayed healing
  • Ksubsequent encounter for fracture with nonunion this code
  • Psubsequent encounter for fracture with malunion
  • Ssequela

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

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name M84.649K, its category, or a range that includes it.

Excludes1 1

These codes carry an Excludes1 note naming M84.649K: they are not reported together with it, unless the two conditions are unrelated.

  • M84.4 Pathological fracture, not elsewhere classified
    pathological fracture in other disease (M84.6-) names M84.6-, which includes this code

Clinical ClassificationClinical

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

CCSR MUS015
Pathological fracture, subsequent encounter
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Fractures

A fracture is a break in a bone. Fractures are usually caused by injuries. Since they can sometimes be serious, it's important to get medical care right away if you think you have a fracture.

The full article covers:

  • What is a fracture?
  • What are the different types of fractures?
  • What causes fractures?
  • What are the symptoms of a fracture?
  • How are fractures diagnosed?
  • What are the treatments for fractures?
  • Can fractures be prevented?

Read the full article at MedlinePlus

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

Convert M84.649K to ICD-9-CMHistory

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

ICD-9-CM
733.82 Nonunion of fracture
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 M84.649KOverview

Is M84.649K (Pathological fracture in other disease, unspecified hand) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report pathological fracture in other disease, unspecified hand, subsequent encounter for fracture with nonunion on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What does the 7th character K in M84.649K mean?

The final character K reports a subsequent encounter where the pathological fracture in other disease, unspecified hand has failed to heal, called a nonunion. In this category the CMS Tabular List defines K as "subsequent encounter for fracture with nonunion".

What MS-DRG does M84.649K group to?

When pathological fracture in other disease, unspecified hand, subsequent encounter for fracture with nonunion is the principal diagnosis on an inpatient stay, it groups to MS-DRG 564, 566, 565, with relative weights from 0.7374 to 1.4909 depending on complications. Higher weights mean higher Medicare reimbursement.

Is M84.649K a CC or MCC?

CMS lists M84.649K 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 5,561 closely related codes in its exclusion list.

Can M84.649K be reported with a code from M80?

Not as a rule. The Excludes1 note at M84.6, which applies to M84.649K, lists "pathological fracture in osteoporosis (M80.-)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).