ICD-10-CM · Hip

M91.80

Juvenile osteochondrosis affecting the hip or pelvis region that does not fit a more specific named subtype (such as Legg-Calvé-Perthes, coxa plana, pseudocoxalgia, or coxa magna), coded here when the affected leg is not documented.

Verified May 8, 2026 · 6 sources ↓

Status: Billable
Chapter: 13
Related CPT: 8
Region: Hip

Drawn from CDCAAPCICD10DataFindacodeNIH

Documentation tips

What should appear in the chart to support M91.80.

Source · Editorial brief grounded in 6 cited references ↓

Document the specific leg affected (right or left) by name to allow migration from M91.80 to M91.81 or M91.82 — 'unspecified' should not be the permanent code once imaging is reviewed.
Confirm and record the diagnosis type: if osteochondrosis follows reduction of congenital hip dislocation, the Applicable To note under M91.8 supports this code — note that history in the chart.
Record imaging modality and findings (X-ray Catterall/Herring grade, MRI avascular necrosis pattern, fragmentation stage) to justify the juvenile osteochondrosis diagnosis and distinguish it from SUFE or other conditions.
Document patient age to establish the 'juvenile' qualifier — this code applies to skeletally immature patients; adult avascular necrosis of the femoral head maps to M87-series codes.
If a named subtype is clinically present (Legg-Calvé-Perthes → M91.1x, coxa plana → M91.2x), use the specific code rather than the 'other' catch-all M91.8x.

Related CPT procedures

Procedure codes commonly billed with M91.80. Linking the right diagnosis to the right procedure is what establishes medical necessity.

Source · CMS LCDs · AAOS specialty guidance · claims-pattern analysis

27093 $232.47

Injection of contrast material into the hip joint to enable arthrographic X-ray imaging, performed without anesthesia.

27095 $325.66

Injection into the hip joint with anesthesia to introduce contrast material for arthrographic imaging of the hip.

27120 $1,182.73

Surgical reshaping or reconstruction of the acetabulum (hip socket) to correct deformity, relieve impingement, or address dysplasia — performed without prosthetic joint replacement.

73502 $48.77

Radiologic exam of a single hip, capturing two or three views, including the pelvis when performed.

73521 $41.75

Bilateral hip X-ray examination capturing two radiographic views of both hips, including the pelvis when performed.

73523 $61.46

Radiologic examination of both hips, including the pelvis when performed, requiring a minimum of five views captured from multiple projections.

27299 View procedure details

77080 View procedure details

Common coding pitfalls

The recurring mistakes coders make with M91.80 and adjacent codes.

Source · Editorial brief grounded in CDC ICD-10-CM tabular guidance, AAOS coding references, and cited references ↓

Assigning M91.80 when laterality is documented: once the chart identifies right or left, you must use M91.81 or M91.82 — unspecified is not acceptable when the information exists.
Coding M91.80 alongside a slipped upper femoral epiphysis code (M93.0–): the category-level Excludes1 prohibits simultaneous use of M91 and M93.0 codes — choose the correct diagnosis.
Using M91.80 for adult avascular necrosis of the femoral head: M91.8x is restricted to juvenile (skeletally immature) patients; adult AVN belongs in the M87 series.
Defaulting to M91.80 instead of a more specific M91 subtype when the clinical presentation actually meets criteria for Legg-Calvé-Perthes (M91.1x), coxa plana (M91.2x), pseudocoxalgia (M91.3x), or coxa magna (M91.4x).
Omitting an additional code for associated chondrolysis (M94.3) when it is documented — the M91 category notes permit this additive coding.

Clinical context

Source · Editorial summary grounded in 6 cited references ↓

M91.80 captures pediatric avascular or degenerative osteochondrosis of the hip and pelvis that falls outside the named conditions enumerated elsewhere in the M91 category — including juvenile osteochondrosis arising after reduction of congenital hip dislocation. The '0' sixth character signals unspecified laterality; use M91.81 (right) or M91.82 (left) whenever the treating clinician documents which leg is involved. Default to M91.80 only when side is genuinely not documented, not as a convenience code.

M91.80 sits under the category-level Excludes1 note barring simultaneous use with slipped upper femoral epiphysis (nontraumatic) codes (M93.0–). That is a hard exclusion: if SUFE is the documented diagnosis, do not also assign M91.80. Research using Korean NHIS data grouped M91.8 with M91.1 and M91.9 when studying Legg-Calvé-Perthes disease comorbidities, confirming that M91.8 functions as a clinically related 'catch-all' for femoral head and pelvic osteochondrosis not otherwise specified.

In orthopedic practice, M91.80 most commonly appears when imaging reveals avascular necrosis or fragmentation patterns in the pediatric hip consistent with osteochondrosis, but the clinical presentation or documentation does not satisfy the criteria for a named subtype, or when laterality has not yet been confirmed at the time of coding. Once laterality is established — typically on X-ray or MRI — migrate to M91.81 or M91.82 to improve specificity and support payer review.

Sibling codes

Other billable codes under M91.8 (laterality / anatomic variants).

M91.82

Other juvenile osteochondrosis of hip and pelvis, left leg

M91.81

Other juvenile osteochondrosis of hip and pelvis, right leg

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 6 cited references ↓

01When should I use M91.80 instead of M91.81 or M91.82?

Use M91.80 only when the treating clinician has not yet documented which leg is affected — for example, at a first encounter before imaging is reviewed. Once laterality is confirmed, update to M91.81 (right) or M91.82 (left).

02What distinguishes M91.80 from M91.10 (Legg-Calvé-Perthes, unspecified leg)?

M91.1x is reserved for confirmed Legg-Calvé-Perthes disease — juvenile osteochondrosis of the femoral head with characteristic clinical and imaging features. M91.80 is for other or unclassified juvenile osteochondrosis of the hip/pelvis, including post-reduction cases, that do not meet named-subtype criteria.

03Can M91.80 and a slipped upper femoral epiphysis code be assigned together?

No. The category-level Excludes1 note under M91 prohibits simultaneous coding with slipped upper femoral epiphysis (nontraumatic) codes (M93.0–). Assign only the diagnosis that best reflects the clinical condition.

04Is M91.80 appropriate for an adult patient with avascular necrosis of the femoral head?

No. The M91 category is explicitly for juvenile osteochondrosis in skeletally immature patients. Adult avascular necrosis of the femoral head is coded from the M87 series (e.g., M87.051–M87.052 for traumatic osteonecrosis, or M87.351 for decompression sickness-related AVN).

05Should I add a code for chondrolysis when it is documented alongside M91.80?

Yes. The M91 category instructs coders to use an additional code for associated chondrolysis (M94.3) when that condition is documented. M91.80 alone will not capture the chondrolysis component.

06Does M91.80 require a 7th character?

No. M91.80 is a 5-character billable code with no 7th-character extension requirement. Seventh-character extensions apply to injury (S-code) and fracture categories, not to M-code chondropathy codes.

07Can M91.80 be used when juvenile osteochondrosis follows reduction of a congenital hip dislocation?

Yes. The Applicable To note under M91.8 explicitly includes 'juvenile osteochondrosis after reduction of congenital dislocation of hip,' making M91.8x the correct code family for that scenario.

Sources & references

Editorial content was developed using the following public sources. Last verified May 8, 2026.

Mira AI Scribe

Mira AI Scribe captures patient age, affected leg (right, left, or not yet determined), imaging findings (X-ray fragmentation pattern, MRI signal changes, avascular necrosis stage), and any prior history of congenital hip dislocation with surgical reduction. Documenting laterality at the time of the encounter prevents landing permanently on the unspecified M91.80 and avoids payer specificity denials on follow-up claims.

See how Mira captures M91.80 documentation