2027 ICD-10-CM Diagnosis Code M84.659APathological fracture in other disease, hip, unspecified, initial encounter for fracture
ICD-10-CM Codes›M00–M99›M80-M85›M84
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 402
- 7th Character A — Initial Encounter for Fracture
- Not Chronic
M84.659A is a billable ICD-10-CM diagnosis code for pathological fracture in other disease, hip, unspecified, initial encounter for fracture. The 7th character A means initial encounter for fracture, used while the patient is receiving active treatment. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 521 through 522, 542 through 544, 791, 793. 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 214 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Pathological fracture, initial encounter.
For Medicare Advantage risk adjustment, M84.659A maps to CMS-HCC Category 402 (Hip Fracture/Dislocation) under the V28 model, adding a risk factor of about 0.467 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
M84.659A maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2027.
Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to M84.659A: 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.
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.
- traumatic fracture of bone-see fracture, by site
- 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.
- underlying condition
Notes
General instructions on how these codes are used.
- 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.
- The appropriate 7th character is to be added to each code from subcategory M84.6:
- Ainitial encounter for fracture this code
- Dsubsequent encounter for fracture with routine healing
- Gsubsequent encounter for fracture with delayed healing
- Ksubsequent encounter for fracture with nonunion
- 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 M84.659A, its category, or a range that includes it.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
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 M84.659A to ICD-9-CMHistory
Code HistoryHistory
Questions About M84.659AOverview
Is M84.659A (Pathological fracture in other disease, hip, unspecified) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report pathological fracture in other disease, hip, unspecified, initial encounter for fracture on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What does the 7th character A in M84.659A mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for pathological fracture in other disease, hip, unspecified, such as an emergency visit or first evaluation. In this category the CMS Tabular List defines A as "initial encounter for fracture".
What MS-DRG does M84.659A group to?
When pathological fracture in other disease, hip, unspecified, initial encounter for fracture is the principal diagnosis on an inpatient stay, it groups to MS-DRG 543, 793, 791, 521, 544, 522, 542, with relative weights from 0.7404 to 4.2192 depending on complications. Higher weights mean higher Medicare reimbursement.
Is M84.659A a CC or MCC?
CMS lists M84.659A 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 214 closely related codes in its exclusion list.
Can M84.659A be reported with a code from M80?
Not as a rule. The Excludes1 note at M84.6, which applies to M84.659A, 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).
What HCC is M84.659A?
M84.659A (pathological fracture in other disease, hip, unspecified, initial encounter for fracture) maps to CMS-HCC Category 402 (Hip Fracture/Dislocation), commonly written as HCC 402, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 170 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 87.
Does M84.659A risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, M84.659A adds a risk adjustment factor of about 0.467 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.089 to 0.570 depending on the payment segment). HCC 402 sits at the top of its hierarchy, so no other condition category supersedes it. See the full factor table on the HCC 402 category page.
