2026 ICD-10-CM Diagnosis Code S52.279JMonteggia's fracture of unspecified ulna, subsequent encounter for open fracture type IIIA, IIIB, or IIIC with delayed healing
S52.279J is a billable ICD-10-CM diagnosis code for Monteggia's fracture of unspecified ulna, subsequent encounter for open fracture type IIIA, IIIB, or IIIC with delayed healing. The 7th character J reports a subsequent encounter for an open fracture (type IIIA, IIIB, or IIIC) with delayed healing. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 559 through 561. The code is exempt from POA reporting. Coders also document this condition as closed fracture of shaft of bone of forearm. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Fracture of the upper limb, subsequent encounter.
Code Identity
Code Classification
Present on Admission (POA)Billing
S52.279J is exempt from POA reporting on inpatient claims to general acute care hospitals. Review other POA exempt codes.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Closed fracture of shaft of bone of forearm
- Closed fracture of shaft of ulna
- Closed Monteggia's fracture
- Monteggia's fracture
- Open fracture of shaft of bone of forearm
- Open fracture of shaft of ulna
- Open Monteggia's fracture
- Traumatic dislocation of radial head
Coding GuidelinesGuidance
The principles of multiple coding of injuries should be followed in coding fractures. Fractures of specified sites are coded individually by site, to the level of detail furnished by medical record content.
A fracture not indicated as open or closed should be coded to closed. A fracture not indicated whether displaced or not displaced should be coded to displaced.
Initial vs. Subsequent Encounter for Fractures
Traumatic fractures are coded using the appropriate 7th character for initial encounter (A, B, C) while the patient is receiving active treatment for the fracture. The appropriate 7th character for initial encounter should also be assigned for a patient who delayed seeking treatment for the fracture or nonunion.
Fractures are coded using the appropriate 7th character for subsequent care for encounters after the patient has completed active treatment of the fracture and is receiving routine care for the fracture during the healing or recovery phase.
Care for complications of surgical treatment for fracture repairs during the healing or recovery phase should be coded with the appropriate complication codes.
Care of complications of fractures, such as malunion and nonunion, should be reported with the appropriate 7th character for subsequent care with nonunion (K, M, N) or subsequent care with malunion (P, Q, R).
The open fracture designations in the assignment of the 7th character for fractures of the forearm, femur and lower leg, including ankle are based on the Gustilo open fracture classification. When the Gustilo classification type is not specified for an open fracture, the 7th character for open fracture type I or II should be assigned (B, E, H, M, Q).
Source: ICD-10-CM Official Guidelines for Coding and Reporting, FY 2026, published by CMS and the National Center for Health Statistics.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Monteggia's Fracture
fracture in the proximal half of the shaft of the ulna, with dislocation of the head of the radius.Closed Monteggia's Fracture
proximal radial head dislocation in association with a proximal ulnar fracture that does not involve a break in the adjacent skin.
Patient EducationClinical
Arm Injuries and Disorders
Of the 206 bones in your body, three of them are in your arm: the humerus, radius, and ulna. Your arms are also made up of muscles, joints, tendons, and other connective tissue. Injuries to any of these parts of the arm can occur during sports, a fall, or an accident.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert S52.279J to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About S52.279JOverview
Is S52.279J (Monteggia's fracture of unspecified ulna) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report Monteggia's fracture of unspecified ulna, subsequent encounter for open fracture type IIIA, IIIB, or IIIC with delayed healing on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character J in S52.279J mean?
The final character J reports a subsequent encounter for an open fracture (type IIIA, IIIB, or IIIC) with delayed healing, in this case involving the Monteggia's fracture of unspecified ulna.
What MS-DRG does S52.279J group to?
When Monteggia's fracture of unspecified ulna, subsequent encounter for open fracture type IIIA, IIIB, or IIIC with delayed healing is the principal diagnosis on an inpatient stay, it groups to MS-DRG 559, 560, 561, with relative weights from 0.8039 to 1.8649 depending on complications. Higher weights mean higher Medicare reimbursement.
Is S52.279J exempt from POA reporting?
Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for Monteggia's fracture of unspecified ulna, subsequent encounter for open fracture type IIIA, IIIB, or IIIC with delayed healing on inpatient claims.
What is the ICD-9 equivalent of S52.279J?
Under the General Equivalence Mappings, Monteggia's fracture of unspecified ulna, subsequent encounter for open fracture type IIIA, IIIB, or IIIC with delayed healing converts to ICD-9-CM V54.12 (aftrcre traum fx low arm). The mapping is approximate, so confirm the match fits the documentation.
Footnotes
[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.
