M92.42 identifies juvenile osteochondrosis of the patella specifically at the left knee — covering both the primary patellar center (Köhler) and secondary patellar center (Sinding-Larsen) variants in a skeletally immature patient.
Verified May 8, 2026 · 5 sources ↓
- Status
- Billable
- Chapter
- 13
- Related CPT
- 5
- Region
- Knee
Documentation tips
What should appear in the chart to support M92.42.
Source · Editorial brief grounded in 5 cited references ↓
- Explicitly state 'left knee' or 'left patella' — do not rely on laterality being inferred from imaging alone.
- Specify whether involvement is at the primary patellar center (Köhler) or secondary patellar center/distal pole (Sinding-Larsen-Johansson) to support clinical completeness.
- Record the patient's skeletal maturity status or age; this code is reserved for juvenile/skeletally immature patients.
- Document imaging findings: patellar pole fragmentation, irregularity, or MRI signal changes consistent with osteochondrosis.
- If bilateral involvement is confirmed, document both knees by name so both M92.41 and M92.42 can be coded — a single unspecified code will not capture the full clinical picture.
Related CPT procedures
Procedure codes commonly billed with M92.42. 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 M92.42 and adjacent codes.
Source · Editorial brief grounded in CDC ICD-10-CM tabular guidance, AAOS coding references, and cited references ↓
- Defaulting to M92.40 (unspecified knee) when laterality is clearly documented in the note — always use M92.42 for a confirmed left-sided diagnosis.
- Confusing Sinding-Larsen-Johansson (patellar osteochondrosis, M92.42) with Osgood-Schlatter disease (tibial tuberosity osteochondrosis, M92.52x) — both cause anterior knee pain in adolescents but involve different anatomic sites.
- Applying this code to an adult patient; osteochondrosis of the patella in a skeletally mature patient does not map to M92.42 — review for a more appropriate chondropathy code.
- Coding M92.42 alone when bilateral disease is documented; ICD-10-CM has no standalone bilateral code under M92.4, so both M92.41 and M92.42 must be reported.
Clinical context
Source · Editorial summary grounded in 5 cited references ↓
M92.42 applies when a pediatric or adolescent patient presents with osteochondrosis affecting the left patella. The parent category M92.4 encompasses two named conditions: Köhler disease of the primary patellar ossification center and Sinding-Larsen-Johansson disease of the secondary patellar center (distal pole). Both involve disruption of ossification in a growing skeleton, typically presenting with anterior knee pain, tenderness at the patella, and imaging findings of fragmentation or irregularity at the affected patellar center. Use M92.42 only when the left knee is explicitly documented — not bilateral, not unspecified.
Laterality is the critical selection axis here. M92.41 codes the right knee; M92.40 covers unspecified laterality and should be a last resort when the treating provider genuinely has not documented which side is affected. If both knees are documented as involved, the approximate synonym list recognizes bilateral involvement — however, ICD-10-CM does not offer a dedicated bilateral code under M92.4, so code both M92.41 and M92.42 when bilateral disease is documented.
M92.42 groups into MS-DRG 553 (Bone diseases and arthropathies with MCC) or 554 (without MCC) under MS-DRG v43.0. Typical encounters involve conservative management — activity modification, physical therapy, patellar taping or bracing — though surgical intervention is occasionally required for refractory cases. Imaging support (plain radiograph or MRI demonstrating patellar pole irregularity, fragmentation, or soft-tissue edema) strengthens the clinical record backing this code.
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 ↓
01What is the difference between M92.41 and M92.42?
02Does M92.42 cover both Köhler disease and Sinding-Larsen-Johansson disease of the left patella?
03Can M92.42 be used for an adult patient with patellar chondropathy?
04How do I code bilateral juvenile patellar osteochondrosis?
05What is the unspecified laterality code if the operative note doesn't specify the knee?
06How does M92.42 differ from Osgood-Schlatter disease?
07Which MS-DRGs does M92.42 map to?
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-/M92.42
- 03aapc.comhttps://www.aapc.com/codes/icd-10-codes/M92.42
- 04aapc.comhttps://www.aapc.com/codes/icd-10-codes/M92.4
- 05vsac.nlm.nih.govhttps://vsac.nlm.nih.gov/context/cs/codesystem/ICD10CM/version/2020/code/M92.42/info
Mira AI Scribe
Mira AI Scribe captures the affected side (left), the patellar location (primary vs. secondary center), the patient's age or skeletal maturity, and imaging findings such as distal patellar pole fragmentation or irregularity. That documentation locks in M92.42 over the unspecified M92.40, preventing a specificity downcode and supporting MS-DRG assignment at audit.
See how Mira captures M92.42 documentation