M02.169 ICD-10-CM Code: Postdysenteric arthropathy, unspecified knee

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for M02.169 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2026Effective: October 1, 2025

Notes without a marker are published on M02.169 itself; “inherited from” names the category or block whose note applies here.

Coder workflow for M02.169

MedCoder structured workflow — derived from this code’s own official record

Before you code M02.169

1. Unspecified does not mean incorrect. When the record gives no greater specificity, M02.169 may be the appropriate code. Check the record for detail that supports a more specific sibling. An unspecified code is for records that do not provide the detail a more specific code needs; a query, not an assumption, is the route to specificity (Guidelines I.A.9.b, I.B.18).

   ReviewM02.161, M02.162

   See the relationships section · Guide: Other vs unspecified (NEC vs NOS) →

2. Laterality is coded in this family. Confirm the side documented — right, left, or bilateral — and select the matching code (this page’s code: unspecified). The unspecified-side code applies only when the record states no side. Laterality is assigned from the documented side; where a bilateral code exists and both sides are documented, it is used instead of two unilateral codes (Guidelines I.B.13).

   ReviewM02.161 · right, M02.162 · left

   Guide: Laterality coding →

3. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with M02.169. Excludes1 conditions are not reported together with this code unless the record shows they are unrelated (Guidelines I.A.12.a).

   See the official tabular notes

Choose the right path

1. Does the record document the detail a more specific sibling code needs?
   Yes → Review the specific siblings in this subcategory.
   No → Continue — M02.169 is appropriate when the documentation goes no further.

   ReviewM02.161, M02.162

2. Does the documentation support a condition named in M02.169’s Excludes1 note?
   Yes → Do not simply proceed: review the excluded code. Both are reported only when the record shows the two conditions are unrelated.
   No → Continue.

   ReviewM35.2, M01, A39.84, B26.85, B06.82, A52.77

3. Is the underlying (etiologic) condition the Code First note names documented?
   Yes → Sequence the underlying condition first, then M02.169.
   No → Continue; do not add an underlying condition the record does not document.

   ReviewA04.6, I33.0

4. Is the side documented?
   Yes → Select the code for the documented side (or the bilateral code when both sides are documented and one exists).
   No → Use the unspecified-side code only when the record states no side; a query is the alternative.

   ReviewM02.161 · right, M02.162 · left

Consider M02.169. Then confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement

Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).

Laterality

Right, left or bilateral as documented; unspecified only when the record states no side (Guidelines I.B.13).

The underlying (etiologic) condition

Named in the Code First note; sequenced before this code when documented (Guidelines I.A.13).

Any detail beyond this code’s title

What the record states that a more specific sibling code would capture — or its absence, which itself supports the unspecified code.

Official instructions as workflow

• Excludes1 — check before selecting M02.169(8 notes)

  Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with M02.169: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

  CompareM35.2, M01, A39.84, B26.85, B06.82, A52.77

  See the official tabular notes · Guidelines I.A.12.a

• Code First — sequencing check(5 notes)

  Coding workflow: Check whether the underlying or etiologic condition the note names is documented. When it is, sequence it before M02.169. Do not add an underlying condition the record does not document.

  ReviewA04.6, I33.0

  See the official tabular notes · Guidelines I.A.13

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Don’t confuse M02.169 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of M02.169 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

• M35.2— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of Behçet's disease moves the case to M35.2; the two are not reported together unless documented as unrelated.

  Full comparison: M02.169 vs M35.2 →

• M01— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of direct infections of joint in infectious and parasitic diseases classified elsewhere moves the case to M01; the two are not reported together unless documented as unrelated.

  Full comparison: M02.169 vs M01 →

• A39.84— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of postmeningococcal arthritis moves the case to A39.84; the two are not reported together unless documented as unrelated.

  Full comparison: M02.169 vs A39.84 →

• B26.85— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of mumps arthritis moves the case to B26.85; the two are not reported together unless documented as unrelated.

  Full comparison: M02.169 vs B26.85 →

• B06.82— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of rubella arthritis moves the case to B06.82; the two are not reported together unless documented as unrelated.

  Full comparison: M02.169 vs B06.82 →

• A52.77— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of syphilis arthritis (late) moves the case to A52.77; the two are not reported together unless documented as unrelated.

  Full comparison: M02.169 vs A52.77 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Verify Before Coding

• CC as a secondary diagnosis (FY2026). Can raise the stay's MS-DRG severity tier.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

Other codes that name M02.169 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 1 Excludes1 note: M01 — Direct infections of joint in infectious and parasitic diseases classified elsewhere (via M02.-).

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 MS-DRG: CC — Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 941 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 2 MS-DRGs: DRG 553 (MDC 08), DRG 554 (MDC 08).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):MUS008 — Immune-mediated/reactive arthropathies (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same condition, opposite side

Same category and title, differing only in which side of the body is affected.

M02.161 — Postdysenteric arthropathy, right knee (right)Compare M02.169 vs M02.161 →, M02.162 — Postdysenteric arthropathy, left knee (left)Compare M02.169 vs M02.162 →

Same CMS-HCC risk category (V28)

CMS maps these diagnoses to the same Hierarchical Condition Category (Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis) for risk-adjusted payment.

M02.132 — Postdysenteric arthropathy, left wrist, M02.139 — Postdysenteric arthropathy, unspecified wrist, M02.141 — Postdysenteric arthropathy, right hand, M02.142 — Postdysenteric arthropathy, left hand, M02.149 — Postdysenteric arthropathy, unspecified hand, M02.151 — Postdysenteric arthropathy, right hip, M02.152 — Postdysenteric arthropathy, left hip, M02.159 — Postdysenteric arthropathy, unspecified hip, M02.161 — Postdysenteric arthropathy, right knee, M02.162 — Postdysenteric arthropathy, left knee, M02.171 — Postdysenteric arthropathy, right ankle and foot, M02.172 — Postdysenteric arthropathy, left ankle and foot, M02.179 — Postdysenteric arthropathy, unspecified ankle and foot, M02.18 — Postdysenteric arthropathy, vertebrae, M02.19 — Postdysenteric arthropathy, multiple sites, M02.80 — Other reactive arthropathies, unspecified site, M02.811 — Other reactive arthropathies, right shoulder, M02.812 — Other reactive arthropathies, left shoulder, M02.819 — Other reactive arthropathies, unspecified shoulder, M02.821 — Other reactive arthropathies, right elbow, +588 more

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Immune-mediated/reactive arthropathies).

M02.132 — Postdysenteric arthropathy, left wrist, M02.139 — Postdysenteric arthropathy, unspecified wrist, M02.141 — Postdysenteric arthropathy, right hand, M02.142 — Postdysenteric arthropathy, left hand, M02.149 — Postdysenteric arthropathy, unspecified hand, M02.151 — Postdysenteric arthropathy, right hip, M02.152 — Postdysenteric arthropathy, left hip, M02.159 — Postdysenteric arthropathy, unspecified hip, M02.161 — Postdysenteric arthropathy, right knee, M02.162 — Postdysenteric arthropathy, left knee, M02.171 — Postdysenteric arthropathy, right ankle and foot, M02.172 — Postdysenteric arthropathy, left ankle and foot, M02.179 — Postdysenteric arthropathy, unspecified ankle and foot, M02.18 — Postdysenteric arthropathy, vertebrae, M02.19 — Postdysenteric arthropathy, multiple sites, M02.30 — Reiter's disease, unspecified site, M02.311 — Reiter's disease, right shoulder, M02.312 — Reiter's disease, left shoulder, M02.319 — Reiter's disease, unspecified shoulder, M02.321 — Reiter's disease, right elbow, +77 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main term “Arthropathy”; these codes share that main term but sit in a different category of the Tabular List.

J38.7 — Other diseases of larynx (cricoarytenoid), K51.90 — Ulcerative colitis, unspecified, without complications (in, ulcerative colitis NEC), K90.81 — Whipple's disease (in, Whipple's disease), L40.50 — Arthropathic psoriasis, unspecified (in, psoriasis NOS), L40.51 — Distal interphalangeal psoriatic arthropathy (distal interphalangeal, psoriatic), L40.52 — Psoriatic arthritis mutilans (mutilans), L40.54 — Psoriatic juvenile arthropathy (juvenile, psoriatic), L40.59 — Other psoriatic arthropathy (psoriatic NEC), L51.9 — Erythema multiforme, unspecified (in, erythema, multiforme), L52 — Erythema nodosum (in, erythema, nodosum), M07.60 — Enteropathic arthropathies, unspecified site (enteropathic), M07.61 — Enteropathic arthropathies, shoulder (enteropathic, shoulder), M07.62 — Enteropathic arthropathies, elbow (enteropathic, elbow), M07.63 — Enteropathic arthropathies, wrist (enteropathic, wrist), M07.64 — Enteropathic arthropathies, hand (enteropathic, hand joint), M07.65 — Enteropathic arthropathies, hip (enteropathic, hip), M07.66 — Enteropathic arthropathies, knee (enteropathic, knee), M07.67 — Enteropathic arthropathies, ankle and foot (enteropathic, ankle), M07.68 — Enteropathic arthropathies, vertebrae (enteropathic, vertebra), M07.69 — Enteropathic arthropathies, multiple sites (enteropathic, multiple site), +72 more

Contextual Map

Every relationship of M02.169 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run M02.169 with this related code in Claim Check

Hierarchy

• M00-M99 — Chapter 13: Diseases of the Musculoskeletal System and Connective Tissue (M00-M99) (M00-M99)[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• M00-M25 — Arthropathies[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• M00-M02 — Infectious arthropathies[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Referenced by Excludes1 notes

• M01 — Direct infections of joint in infectious and parasitic diseases classified elsewhere[Excludes1](via M02.-): “postinfective arthropathy (M02.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Clinical classification (CCSR)

• MUS008 — Immune-mediated/reactive arthropathies[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)

Risk adjustment (CMS-HCC)

• HCC 92 — Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis [CMS-HCC]— CMS-HCC V28 · 2026

MS-DRG Grouper

• CC — Complication or Comorbidity [MS-DRG severity]: “As a secondary diagnosis this code can raise the stay's MS-DRG severity tier (CC).”— CMS MS-DRG Definitions Manual (Appendix C) · FY2026
• DRG 553 — BONE DISEASES AND ARTHROPATHIES WITH MCC[MS-DRG]: “BONE DISEASES AND ARTHROPATHIES WITH MCC (MDC 08)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 554 — BONE DISEASES AND ARTHROPATHIES WITHOUT MCC[MS-DRG]: “BONE DISEASES AND ARTHROPATHIES WITHOUT MCC (MDC 08)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026

MDC crossing

• MDC 08 — Diseases and Disorders of the Musculoskeletal System and Connective Tissue[MDC crossing]: “Diseases and Disorders of the Musculoskeletal System and Connective Tissue — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 18,508 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026

Nearest codes (40)

• M02 — Postinfective and reactive arthropathies[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• M02.119 — Postdysenteric arthropathy, unspecified shoulder[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• M02.12 — Postdysenteric arthropathy, elbow[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• M02.121 — Postdysenteric arthropathy, right elbow[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• M02.122 — Postdysenteric arthropathy, left elbow[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• M02.129 — Postdysenteric arthropathy, unspecified elbow[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• M02.13 — Postdysenteric arthropathy, wrist[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• M02.131 — Postdysenteric arthropathy, right wrist[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• and 32 more

Change history

• FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Relevant guides

• Arthropathy, Osteopathy and Myopathy “in Diseases Classified Elsewhere” →

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data

CMS/CDC ICD-10-CM FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page

Claim edits Official source data

CMS Definitions of Medicare Code Edits — v43.1 (April 2026) Release, file and checksum · Publisher’s page

Inpatient payment groups Official source data

CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v43 Release, file and checksum · Publisher’s page

Risk adjustment Official source data

2026 Mid-Year Final ICD-10 Mappings + Model Software (cms.gov/files/zip/2026-midyear-final-icd-10-mappings.zip, 2026-midyear-final-model-software.zip) — CMS-HCC V28, PY2026 mid-year final release Release, file and checksum · Publisher’s page

Change history and date-of-service validity Official source data

CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page

Comparisons, relationships and the contextual map MedCoder structured relationship

Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears

Summary and FAQ answers MedCoder explanation

Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Nearest Codes in This Family

Official ICD-10-CM classifications closest to M02.169 in its code family, with their registry titles.

• M02.152 — Postdysenteric arthropathy, left hip
• M02.159 — Postdysenteric arthropathy, unspecified hip
• M02.16 — Postdysenteric arthropathy, knee
• M02.161 — Postdysenteric arthropathy, right knee
• M02.162 — Postdysenteric arthropathy, left knee
• M02.17 — Postdysenteric arthropathy, ankle and foot
• M02.171 — Postdysenteric arthropathy, right ankle and foot
• M02.172 — Postdysenteric arthropathy, left ankle and foot
• M02.179 — Postdysenteric arthropathy, unspecified ankle and foot
• M02.18 — Postdysenteric arthropathy, vertebrae

View all codes in the M02 family