M91.0 classifies juvenile osteochondrosis affecting the pelvic bones, including osteochondrosis of the acetabulum, iliac crest (Buchanan), ischiopubic synchondrosis (van Neck), and symphysis pubis (Pierson).

Documentation tips

What should appear in the chart to support M91.0.

Source · Editorial brief grounded in 5 cited references ↓

• Specify the exact pelvic site affected — acetabulum, iliac crest, ischiopubic synchondrosis, or symphysis pubis — to align with the Applicable To entries and demonstrate code selection rationale.
• Document the patient's skeletally immature status (age, open physes on imaging) to justify 'juvenile' classification over adult osteochondrosis codes.
• Record imaging findings (X-ray, MRI, or bone scan) showing fragmentation, sclerosis, or avascular change at the named pelvic site.
• If the provider uses an eponym (Buchanan's disease, van Neck's disease, Pierson's disease), note it in the record — all map to M91.0 per the FY2026 tabular index.
• Distinguish whether the current encounter is for active disease versus a resolved condition with residual deformity, as this affects code selection.

Related CPT procedures

Procedure codes commonly billed with M91.0. 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 M91.0 and adjacent codes.

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

• Assigning M91.1 (Legg-Calvé-Perthes) when the pathology is pelvic rather than femoral head — confirm imaging localization before selecting the subcode.
• Attempting to add a laterality character to M91.0 — unlike M91.1x, this code has no right/left breakdown; it is valid as a 5-character code without further extension.
• Using M92.9 (Juvenile osteochondrosis, unspecified) when the site is documented — M91.0 provides greater specificity and should be used whenever the pelvis is identified.
• Coding M91.0 for an adult patient with pelvic osteochondrosis — the 'juvenile' designation requires skeletally immature presentation; adult equivalents fall elsewhere in the tabular.

Clinical context

Source · Editorial summary grounded in 5 cited references ↓

Inclusion & exclusion notes

Per the official ICD-10-CM Tabular List.

Source · CDC ICD-10-CM Official Tabular List · 2026