Osteochondrosis affecting the patella in a skeletally immature patient, coded when the treating clinician has not specified or documented which knee is involved.
Verified May 8, 2026 · 5 sources ↓
- Status
- Billable
- Chapter
- 13
- Related CPT
- 8
- Region
- Knee
Documentation tips
What should appear in the chart to support M92.40.
Source · Editorial brief grounded in 5 cited references ↓
- Document laterality explicitly — 'right,' 'left,' or 'bilateral' — in every encounter note to avoid defaulting to the unspecified M92.40.
- Record the patient's skeletal maturity status (open vs. closed physes) to support juvenile classification over adult osteochondritis dissecans.
- Specify which patellar center is affected when possible: primary center (Köhler) vs. secondary center (Sinding-Larsen-Johansson) to strengthen clinical documentation.
- Note the mechanism and activity level (e.g., competitive athletics, jumping sports) that aggravates symptoms, supporting medical necessity for conservative or procedural treatment.
- Document imaging findings (plain radiograph, MRI) that confirm patellar osteochondrosis — fragmentation, irregularity, or signal changes at the patellar ossification center.
- Record any prior conservative care (activity modification, physical therapy, NSAID trial) to support escalation to procedural intervention if applicable.
Related CPT procedures
Procedure codes commonly billed with M92.40. Linking the right diagnosis to the right procedure is what establishes medical necessity.
Source · CMS LCDs · AAOS specialty guidance · claims-pattern analysis
Common coding pitfalls
The recurring mistakes coders make with M92.40 and adjacent codes.
Source · Editorial brief grounded in CDC ICD-10-CM tabular guidance, AAOS coding references, and cited references ↓
- Defaulting to M92.40 when laterality is present in the record — always query the note for 'right' or 'left' before using the unspecified code.
- Confusing M92.4x (patellar osteochondrosis) with M92.5x (juvenile osteochondrosis of tibia and fibula / Osgood-Schlatter) — the anatomical site is the patella, not the tibial tubercle.
- Using M92.40 for an adult patient: this code is specifically for juvenile (skeletally immature) patients; osteochondritis dissecans of the patella in adults belongs in the M93 range.
- Reporting M92.40 as a bilateral code — it is unspecified, not bilateral. Code M92.41 and M92.42 together when both knees are documented.
- Failing to add a separate code for any associated symptoms (e.g., joint effusion) when documented, since the osteochondrosis code alone does not capture all billable comorbidities.
Clinical context
Source · Editorial summary grounded in 5 cited references ↓
M92.40 covers juvenile osteochondrosis of the patella when laterality is undocumented or genuinely unknown. The parent category M92.4 encompasses two named conditions: osteochondrosis of the primary patellar ossification center (Köhler disease of the patella) and osteochondrosis of the secondary patellar center (Sinding-Larsen-Johansson syndrome). Both present in skeletally immature patients — typically active adolescents — with anterior knee pain localized to the inferior or central patella, often aggravated by jumping, squatting, or stair climbing.
Use M92.40 only when the record genuinely lacks laterality. If the provider documents right knee, assign M92.41; left knee, assign M92.42. Bilateral presentation is not captured by a single bilateral code in this subcategory — report M92.41 and M92.42 together. M92.40 is classified as a chronic condition indicator by payers, so expect it to appear on problem lists and in longitudinal coding across multiple encounters until the condition resolves.
Do not use M92.40 for patellar osteochondritis dissecans in a skeletally mature patient; that maps elsewhere in the M93 range. Also do not confuse with Osgood-Schlatter disease (M92.5x), which affects the tibial tubercle, not the patella. Postprocedural chondropathies (M96.-) are excluded from the M91-M94 chondropathy range by a Type 1 Excludes note.
Sibling codes
Other billable codes under M92.4 (laterality / anatomic variants).
Frequently asked questions
Source · Generated from the editorial pipeline, verified against 5 cited references ↓
01When should I use M92.40 instead of M92.41 or M92.42?
02Does M92.40 cover both Köhler and Sinding-Larsen-Johansson disease?
03Can M92.40 be used for a bilateral patellar osteochondrosis presentation?
04What distinguishes M92.4x from M93.2x (osteochondritis dissecans)?
05Is a Type 1 Excludes note relevant to M92.40?
06What imaging documentation best supports M92.40 at audit?
07Is M92.40 valid for FY2026 billing?
Sources & references
Editorial content was developed using the following public sources. Last verified May 8, 2026.
- 01CDC ICD-10-CM Tabular List 2026 (effective Oct 1, 2025)
- 02icd10data.comhttps://www.icd10data.com/ICD10CM/Codes/M00-M99/M91-M94/M92-/M92.40
- 03aapc.comhttps://www.aapc.com/codes/icd-10-codes/M92.40
- 04aapc.comhttps://www.aapc.com/codes/icd-10-codes/M92.4
- 05icdlist.comhttps://icdlist.com/icd-10/M92.40
Mira AI Scribe
Mira AI Scribe captures laterality, the specific patellar center involved (primary vs. secondary), imaging findings (radiograph or MRI confirmation of patellar fragmentation or irregularity), the patient's skeletal maturity, and prior conservative care. Documenting these elements at every encounter upgrades M92.40 to the laterality-specific M92.41 or M92.42, preventing payer downcoding and reducing audit exposure on claims with procedure codes tied to a specific knee.
See how Mira captures M92.40 documentation