2027 ICD-10-CM Diagnosis Code M48.51XACollapsed vertebra, not elsewhere classified, occipito-atlanto-axial region, initial encounter for fracture
ICD-10-CM Codes›M00–M99›M45-M49›M48
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 401
- 7th Character A — Initial Encounter for Fracture
- Not Chronic
M48.51XA is a billable ICD-10-CM diagnosis code for collapsed vertebra, not elsewhere classified, occipito-atlanto-axial region, 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 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 Stress fracture, initial encounter.
For Medicare Advantage risk adjustment, M48.51XA maps to CMS-HCC Category 401 (Vertebral Fractures without Spinal Cord Injury) under the V28 model, adding a risk factor of about 0.522 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
M48.51XA 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 M48.51XA: its own notes plus those printed at M48.5 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.
- current injury - see Injury of spine, by body region
- fatigue fracture of vertebra (M48.4)
- pathological fracture of vertebra due to neoplasm (M84.58)
- pathological fracture of vertebra due to other diagnosis (M84.68)
- pathological fracture of vertebra due to osteoporosis (M80.-)
- pathological fracture NOS (M84.4-)
- stress fracture of vertebra (M48.4-)
- traumatic fracture of vertebra (S12.-, S22.-, S32.-)
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.
- 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.
- 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 M48.5:
- Ainitial encounter for fracture this code
- Dsubsequent encounter for fracture with routine healing
- Gsubsequent encounter for fracture with delayed healing
- Ssequela of fracture
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name M48.51XA, its category, or a range that includes it.
Excludes1 4
These codes carry an Excludes1 note naming M48.51XA: they are not reported together with it, unless the two conditions are unrelated.
- G55 Nerve root and plexus compressions in diseases classified elsewherenerve root compression (due to) (in) spondylopathies (M46.-, M48.-) names M48.-, which includes this code
- M80 Osteoporosis with current pathological fracturecollapsed vertebra NOS (M48.5) names M48.5, which includes this code
- M80 Osteoporosis with current pathological fracturewedging of vertebra NOS (M48.5) names M48.5, which includes this code
- M84.4 Pathological fracture, not elsewhere classifiedcollapsed vertebra NEC (M48.5) names M48.5, which includes this code
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 M48.51XA to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About M48.51XAOverview
Is M48.51XA a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report collapsed vertebra, not elsewhere classified, occipito-atlanto-axial region, initial encounter for fracture on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What does the 7th character A in M48.51XA mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for collapsed vertebra, not elsewhere classified, occipito-atlanto-axial region, 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 M48.51XA group to?
When collapsed vertebra, not elsewhere classified, occipito-atlanto-axial region, initial encounter for fracture is the principal diagnosis on an inpatient stay, it groups to MS-DRG 543, 793, 791, 544, 542, with relative weights from 0.7404 to 4.2192 depending on complications. Higher weights mean higher Medicare reimbursement.
Is M48.51XA a CC or MCC?
CMS lists M48.51XA 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 M48.51XA be reported with M48.4?
Not as a rule. The Excludes1 note at M48.5, which applies to M48.51XA, lists "fatigue fracture of vertebra (M48.4)". 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 M48.51XA?
M48.51XA (collapsed vertebra, not elsewhere classified, occipito-atlanto-axial region, initial encounter for fracture) maps to CMS-HCC Category 401 (Vertebral Fractures without Spinal Cord Injury), commonly written as HCC 401, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 169 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 M48.51XA risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, M48.51XA adds a risk adjustment factor of about 0.522 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.231 to 0.622 depending on the payment segment). HCC 401 sits at the top of its hierarchy, so no other condition category supersedes it. See the full factor table on the HCC 401 category page.
