2026 ICD-10-CM Diagnosis Code M01.X61Direct infection of right knee in infectious and parasitic diseases classified elsewhere
ICD-10-CM Codes›M00–M99›M00-M02›M01
- Billable — Valid for Submission
- Not Chronic
M01.X61 is a billable ICD-10-CM diagnosis code for direct infection of right knee in infectious and parasitic diseases classified elsewhere. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 485 through 487, 548 through 550. The code is a manifestation code that cannot be reported as the principal diagnosis. Coders also document this condition as bilateral infective arthritis of knees. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Infective arthritis.
Code Identity
Code Classification
Code EditsBilling
Medicare Code Editor checks that affect claim validity for M01.X61.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Bilateral infective arthritis of knees
- Bilateral viral arthritis of knee joints
- Viral arthritis of joint of left knee
- Viral arthritis of joint of right knee
- Viral arthritis of knee
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Infectious Arthritis
Most kinds of arthritis cause pain and swelling in your joints. Joints are places where two bones meet, such as your elbow or knee. Infectious arthritis is an infection in the joint. The infection comes from a bacterial, viral, or fungal infection that spreads from another part of the body. Symptoms of infectious arthritis include:
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert M01.X61 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About M01.X61Overview
Is M01.X61 a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report direct infection of right knee in infectious and parasitic diseases classified elsewhere on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does M01.X61 group to?
On inpatient claims, direct infection of right knee in infectious and parasitic diseases classified elsewhere maps to MS-DRG 485, 486, 487, 548, 549, 550, with relative weights from 0.8741 to 3.2271 depending on complications. Higher weights mean higher Medicare reimbursement.
Can M01.X61 be a principal diagnosis?
No. This is a manifestation code: direct infection of right knee in infectious and parasitic diseases classified elsewhere describes the manifestation of an underlying disease rather than the disease itself, so the underlying condition is sequenced first.
What is the ICD-9 equivalent of M01.X61?
Under the General Equivalence Mappings, direct infection of right knee in infectious and parasitic diseases classified elsewhere converts to ICD-9-CM 711.46 (bact arthritis-l/leg), 711.56 (viral arthritis-l/leg), and 711.66 (mycotic arthritis-l/leg). 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.
