M91.81 identifies juvenile osteochondrosis of the hip and pelvis affecting the right leg, in a category that captures osteochondrosis presentations not classified under Legg-Calvé-Perthes disease, coxa plana, pseudocoxalgia, or coxa magna.
Verified May 8, 2026 · 4 sources ↓
- Status
- Billable
- Chapter
- 13
- Related CPT
- 10
- Region
- Hip
Documentation tips
What should appear in the chart to support M91.81.
Source · Editorial brief grounded in 4 cited references ↓
- Confirm and document laterality explicitly as 'right' hip or pelvis — this is what drives the 6th-character distinction between M91.81, M91.82, and M91.80.
- Document the patient's age and skeletal maturity status; M91 codes are juvenile osteochondrosis diagnoses and should reflect a pediatric or adolescent patient.
- If osteochondrosis follows reduction of congenital hip dislocation, note that history explicitly — the Applicable To language for M91.8 specifically covers this scenario.
- Record imaging findings that support the diagnosis: plain radiograph changes (femoral head flattening, joint space changes), MRI signal abnormalities, or bone scan findings as applicable.
- Distinguish clinically whether the presentation fits a named M91 variant (Legg-Calvé-Perthes, coxa plana, pseudocoxalgia, coxa magna) — if it does, those more specific codes take precedence over M91.81.
Related CPT procedures
Procedure codes commonly billed with M91.81. 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 M91.81 and adjacent codes.
Source · Editorial brief grounded in CDC ICD-10-CM tabular guidance, AAOS coding references, and cited references ↓
- Coding M91.81 alongside M93.0 (slipped upper femoral epiphysis, nontraumatic) violates the Type 1 Excludes note at the M91 category level — these codes can never be assigned together for the same joint.
- Using M91.81 when a named variant applies: if documentation supports Legg-Calvé-Perthes, code M91.11 (right leg); if coxa plana, code M91.21 (right hip). M91.81 is for presentations that genuinely don't fit any named subcategory.
- Defaulting to M91.80 (unspecified leg) when laterality is documented as right — always assign the laterality-specific code when the record supports it.
- Applying M91.81 to an adult patient without confirming the diagnosis originated in or is being managed as juvenile osteochondrosis — the M91 block is disease-specific to juvenile onset.
Clinical context
Source · Editorial summary grounded in 4 cited references ↓
M91.81 falls under the M91.8 subcategory — 'Other juvenile osteochondrosis of hip and pelvis' — and is reserved for right-sided cases that don't meet the criteria for the more specifically named conditions in the M91 category. This includes juvenile osteochondrosis occurring after reduction of congenital hip dislocation, a clinical scenario explicitly noted in the Applicable To language for M91.8. If the condition is bilateral or the affected side is undocumented, drop to M91.80 (unspecified leg).
The entire M91 category carries a Type 1 Excludes note for slipped upper femoral epiphysis (nontraumatic), coded at M93.0. Never assign M91.81 simultaneously with M93.0. If documentation points to SUFE, code there instead — these two conditions cannot coexist under the same encounter for the same joint.
This code applies to a pediatric and adolescent population. The diagnosis should be supported by clinical findings and imaging (plain radiograph, MRI, or bone scan) demonstrating osteochondrosis of the right hip or pelvis region. When the presentation maps to a named variant — Legg-Calvé-Perthes (M91.11), coxa plana (M91.21), pseudocoxalgia (M91.31), or coxa magna (M91.41) — use that more specific right-sided code rather than M91.81.
Sibling codes
Other billable codes under M91.8 (laterality / anatomic variants).
Frequently asked questions
Source · Generated from the editorial pipeline, verified against 4 cited references ↓
01What is the difference between M91.81 and M91.11?
02Can M91.81 be used for an adult patient?
03Can M91.81 and M93.0 be coded together?
04When does M91.81 apply after congenital hip dislocation treatment?
05What imaging supports the M91.81 diagnosis?
06What is the unspecified-laterality alternative if the side isn't documented?
Sources & references
Editorial content was developed using the following public sources. Last verified May 8, 2026.
Mira AI Scribe
Mira captures right-side laterality, patient age, imaging findings (radiograph or MRI changes in the right hip/pelvis), and any history of prior congenital hip dislocation reduction — all of which support M91.81 over the unspecified M91.80 or a named-variant code. Accurate specificity prevents downcoding audits and ensures payer acceptance for procedures tied to this diagnosis.
See how Mira captures M91.81 documentation