Chronic, repetitive incomplete dislocation of the right patella in which the kneecap repeatedly slides partially out of the trochlear groove without fully dislocating.

Documentation tips

What should appear in the chart to support M22.11.

Source · Editorial brief grounded in 6 cited references ↓

• Explicitly state 'right knee' and 'recurrent subluxation' — not just 'patellar instability' — so the code selection is unambiguous.
• Document the number or frequency of subluxation episodes (e.g., 'third episode in six months') to justify the 'recurrent' qualifier over a traumatic S-code.
• Record any imaging findings that support instability: patellar tilt on axial X-ray, trochlear dysplasia grade on MRI, bone bruise pattern at the medial patellar facet and lateral femoral condyle.
• Note any prior conservative treatment (physical therapy, patellar-stabilizing bracing, activity modification) when surgical authorization is anticipated — payers commonly require failed conservative care documentation.
• If chondromalacia or cartilage damage is identified concurrently, document it explicitly so M22.41 can be reported as an additional diagnosis.

Related CPT procedures

Procedure codes commonly billed with M22.11. 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 M22.11 and adjacent codes.

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

• Using M22.11 for a first-time or acute patellar subluxation — a single traumatic event codes to S83.0- with the appropriate 7th character (A, D, or S), not M22.11.
• Defaulting to M22.10 (unspecified knee) when the provider clearly documents the right side — laterality is required for specificity; unspecified risks downcoding and payer edits.
• Conflating recurrent subluxation (M22.11) with recurrent full dislocation (M22.01); subluxation is incomplete displacement — verify the provider's exact terminology before selecting between these two codes.
• Omitting a separate code for chondromalacia patellae (M22.41) when it is documented — it is not bundled into M22.11 and should be reported as an additional diagnosis.
• Applying a 7th-character extension to M22.11 — M-codes in Chapter 13 do not use 7th-character encounter extensions (A/D/S); those apply to S-codes only.

Clinical context

Source · Editorial summary grounded in 6 cited references ↓

Sibling codes

Other billable codes under M22.1 (laterality / anatomic variants).