2027 ICD-10-CM Diagnosis Code T84.621AInfection and inflammatory reaction due to internal fixation device of left femur, initial encounter

ICD-10-CM Codes›S00–T88›T80-T88›T84

ICD-10-CM T84.621A
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

T84.621A is a billable ICD-10-CM diagnosis code for infection and inflammatory reaction due to internal fixation device of left femur, initial encounter. The 7th character A marks it as an initial encounter code, 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 400, 559 through 561. 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 264 closely related codes. Coders also document this condition as infection of femur associated with internal fixation device. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Complication of internal orthopedic device or implant, initial encounter.

T84.621A no longer risk-adjusts for Medicare Advantage: it mapped to HCC 176 under the retired CMS-HCC V24 model through payment year 2025 but maps to no category in the live V28 model. It still risk-adjusts in the PACE (CMS-HCC V22) category 176, ESRD (V21) category 176, and ESRD (V24) category 176 for payment year 2027.

Code Identity

ICD-10-CM Code
T84.621A
Billable Status
Yes — Valid for Submission
Code Describes
Infection and inflammatory reaction due to internal fixation device of left femur, initial encounter
Short Description
Infect/inflm reaction due to int fix of left femur, init
Parent Code
T84.621
Infection and inflammatory reaction due to internal fixation device of left femur

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionT80-T88Complications of surgical and medical care, not elsewhere classified
CategoryT84Complications of internal orthopedic prosthetic devices, implants and grafts
This CodeT84.621AInfection and inflammatory reaction due to internal fixation device of left femur, initial encounter

Medicare Risk Adjustment (HCC)Billing

T84.621A no longer risk-adjusts for Medicare Advantage: it maps to no payment category in the live CMS-HCC V28 model, although it still risk-adjusts in the other CMS models shown below.

CMS-HCC V28 (Medicare Advantage Payment Model)
Not mapped
Dropped in V28 see all codes that no longer risk-adjust
Prior Model (CMS-HCC V24)
HCC 176
V24 retired last contributed to a Medicare Advantage risk score in payment year 2025
Other CMS Models
PACE (CMS-HCC V22): HCC 176 · ESRD (V21): HCC 176 · ESRD (V24): HCC 176
ESRD V21 weights: 0.000 dialysis, 0.599 functioning graft · ESRD V24 weights: 0.000 dialysis, 0.586–1.017 functioning graft
Part D (RxHCC)
Not mapped
T84.621A does not risk-adjust in the RxHCC prescription drug model

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.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Infection of femur associated with internal fixation device
  • Left femur infection associated with internal fixation device

Coding GuidelinesGuidance

The appropriate 7th character is to be added to each code from block Complications of internal orthopedic prosthetic devices, implants and grafts (T84). Use the following options for the applicable episode of care:

  • A - initial encounter
  • D - subsequent encounter
  • S - sequela

Source: ICD-10-CM Official Guidelines for Coding and Reporting, FY 2027, published by CMS and the National Center for Health Statistics.

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to T84.621A: its own notes plus those printed at T84.6, T84, block T80-T88, and Chapter 19. 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 T84 Complications of internal orthopedic prosthetic devices, implants and grafts applies to 357 codes
  • failure and rejection of transplanted organs and tissues (T86.-)
  • fracture of bone following insertion of orthopedic implant, joint prosthesis or bone plate (M96.6)
From Block T80-T88 Complications of surgical and medical care, not elsewhere classified applies to 1,683 codes
  • any encounters with medical care for postprocedural conditions in which no complications are present, such as:
  • artificial opening status (Z93.-)
  • closure of external stoma (Z43.-)
  • fitting and adjustment of external prosthetic device (Z44.-)
  • burns and corrosions from local applications and irradiation (T20-T32)
  • complications of surgical procedures during pregnancy, childbirth and the puerperium (O00-O9A)
  • mechanical complication of respirator [ventilator] (J95.850)
  • poisoning and toxic effects of drugs and chemicals (T36-T65 with fifth or sixth character 1-4 or 6)
  • postprocedural fever (R50.82)
  • specified complications classified elsewhere, such as:
  • cerebrospinal fluid leak from spinal puncture (G97.0)
  • colostomy malfunction (K94.0-)
  • disorders of fluid and electrolyte imbalance (E86-E87)
  • functional disturbances following cardiac surgery (I97.0-I97.1)
  • intraoperative and postprocedural complications of specified body systems (D78.-, E36.-, E89.-, G97.3-, G97.4, H59.3-, H59.-, H95.2-, H95.3, I97.4-, I97.5, J95.6-, J95.7, K91.6-, L76.-, M96.-, N99.-)
  • ostomy complications (J95.0-, K94.-, N99.5-)
  • postgastric surgery syndromes (K91.1)
  • postlaminectomy syndrome NEC (M96.1)
  • postmastectomy lymphedema syndrome (I97.2)
  • postsurgical blind-loop syndrome (K91.2)
  • ventilator associated pneumonia (J95.851)
From Chapter 19 (S00-T88) Injury, poisoning and certain other consequences of external causes applies to 41,187 codes

Use Additional Code

Add a second code, after this one, to fully describe the condition.

From T84.6 Infection and inflammatory reaction due to internal fixation device applies to 51 codes
  • code to identify infection
From Block T80-T88 Complications of surgical and medical care, not elsewhere classified applies to 1,683 codes
  • code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)
  • code(s) to identify the specified condition resulting from the complication
  • code to identify devices involved and details of circumstances (Y62-Y82)
From Chapter 19 (S00-T88) Injury, poisoning and certain other consequences of external causes applies to 41,187 codes
  • code to identify any retained foreign body, if applicable (Z18.-)

Notes

General instructions on how these codes are used.

From Chapter 19 (S00-T88) Injury, poisoning and certain other consequences of external causes applies to 41,187 codes
  • Use secondary code(s) from Chapter 20, External causes of morbidity, to indicate cause of injury. Codes within the T section that include the external cause do not require an additional external cause code
  • The chapter uses the S-section for coding different types of injuries related to single body regions and the T-section to cover injuries to unspecified body regions as well as poisoning and certain other consequences of external causes.

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 T84 Complications of internal orthopedic prosthetic devices, implants and grafts applies to 357 codes
  • The appropriate 7th character is to be added to each code from category T84
Values for category T84 Encounter: Initial, Subsequent, Sequela
  • Ainitial encounter this code
  • Dsubsequent encounter
  • 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 T84.621A, its category, or a range that includes it.

Excludes1 1

These codes carry an Excludes1 note naming T84.621A: they are not reported together with it, unless the two conditions are unrelated.

  • Z47.2 Encounter for removal of internal fixation device
    infection or inflammatory reaction to internal fixation device (T84.6-) names T84.6-, which includes this code

Excludes2 4

These codes carry an Excludes2 note naming T84.621A: its condition is not part of those codes, and both may be reported when the patient has both.

  • M96 Intraoperative and postprocedural complications and disorders of musculoskeletal system, not elsewhere classified
    complications of internal orthopedic prosthetic devices, implants and grafts (T84.-) names T84.-, which includes this code
  • M96.6 Fracture of bone following insertion of orthopedic implant, joint prosthesis, or bone plate
    complication of internal orthopedic devices, implants or grafts (T84.-) names T84.-, which includes this code
  • T80.2 Infections following infusion, transfusion and therapeutic injection
    infections specified as due to prosthetic devices, implants and grafts (T82.6-T82.7, T83.5-T83.6, T84.5-T84.7, T85.7) names T84.5-T84.7, which includes this code
  • T81.4 Infection following a procedure
    infection due to prosthetic devices, implants and grafts (T82.6-T82.7, T83.5-T83.6, T84.5-T84.7, T85.7) names T84.5-T84.7, which includes this code

Clinical ClassificationClinical

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

CCSR INJ035
Complication of internal orthopedic device or implant, initial 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 T84.621A to ICD-9-CMHistory

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

ICD-9-CM
996.67 React-oth int ortho dev
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 T84.621AOverview

Is T84.621A a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report infection and inflammatory reaction due to internal fixation device of left femur, initial encounter on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What does the 7th character A in T84.621A mean?

The final character A marks the initial encounter: use it while the patient is receiving active treatment for infection and inflammatory reaction due to internal fixation device of left femur, such as an emergency visit or first evaluation.

What MS-DRG does T84.621A group to?

When infection and inflammatory reaction due to internal fixation device of left femur, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 559, 561, 560, 400, with relative weights from 0.8258 to 2.0249 depending on complications. Higher weights mean higher Medicare reimbursement.

Is T84.621A a CC or MCC?

CMS lists T84.621A 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 264 closely related codes in its exclusion list.

Does T84.621A need an additional code?

When the condition applies, yes. The Use Additional Code note at T84.6, which applies to T84.621A, reads: code to identify infection. The additional code is reported after T84.621A.

Does T84.621A risk-adjust for Medicare Advantage payment?

Not for Medicare Advantage. T84.621A mapped to HCC 176 in the retired CMS-HCC V24 model, which last determined payment in 2025, but it maps to no category in the live V28 model; see all codes that no longer risk-adjust. It still risk-adjusts in the PACE (CMS-HCC V22) category 176 (Complications of Specified Implanted Device or Graft), ESRD (V21) category 176 (Complications of Specified Implanted Device or Graft), and ESRD (V24) category 176 (Complications of Specified Implanted Device or Graft).