ICD-10-CM 2027
ICD-10 code for Knock knee
From the official ICD-10-CM alphabetic index entry “Knock knee (acquired)”. Page updated September 29, 2026.
About coding Knock knee
The ICD-10-CM code for Knock knee is M21.06 (Valgus deformity, not elsewhere classified, knee). The official index lists 1 more specific code, so check the documentation for details such as type, cause, site or severity before settling on M21.06.
Within M21.0 (valgus deformity, not elsewhere classified), M21.06 is specifically for valgus deformity, not elsewhere classified, knee. Related codes cover unspecified site (M21.00), elbow (M21.02), hip (M21.05) and ankle (M21.07).
To report this condition, pick the subcode that matches the documentation: M21.061 (knee), M21.062 (knee) and M21.069 (knee).
It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.
More specific Knock knee codes (official index)
- congenital Q74.1 — Congenital malformation of knee
Common questions about Knock knee ICD-10 codes
What is the ICD-10 code for Knock knee?
- M21.06 — Valgus deformity, not elsewhere classified, knee (a header code; report a more specific subcode). More specific codes apply when the documentation supports them: Q74.1.
What is the ICD-10 code for congenital knock knee?
- Q74.1 — Congenital malformation of knee.
Is M21.06 billable?
- No. M21.06 is a header code. Report one of its more specific subcodes instead.