Is M66.1 a billable ICD-10-CM code?

No. M66.1 is a non-billable header code. Code to a higher level of specificity using one of its child codes.

Where does M66.1 sit in the tabular list?

Diseases of the musculoskeletal system and connective tissue (M00-M99), in the block Disorders of synovium and tendon (M65-M67).

M66.1

M66.1 — Rupture of synovium

Non-billable headerICD-10-CM

M66.1 is a non-billable header ICD-10-CM code for rupture of synovium. It cannot be billed on its own: choose one of the more specific child codes below.

Excludes2 — not included here, but may coexist

The excluded condition is not part of this code, but a patient can have both. You may code both.

rupture of popliteal cyst (M66.0)

Inclusion terms

Alternative wordings a physician may use in the chart for this same code.

Rupture of synovial cyst

Other codes that can never be billed with M66.1

These codes carry an Excludes1 note pointing at M66.1. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading M66.1 alone.

M71.3Other bursal cyst

Risk adjustment

M66.1 does not map to an HCC and does not risk-adjust under CMS-HCC V28. That is normal — most ICD-10 codes do not. It still needs to be coded correctly; it just will not move a RAF score.

Code to one of these instead M66.1

8 child codes. Green means billable.

Related codes at this level

Codes that share M66. If M66.1 is not quite right, the correct code is usually one of these.

Questions about M66.1

Is M66.1 a billable ICD-10-CM code?: No. M66.1 is a non-billable header code. Code to a higher level of specificity using one of its child codes.
Where does M66.1 sit in the tabular list?: Diseases of the musculoskeletal system and connective tissue (M00-M99), in the block Disorders of synovium and tendon (M65-M67).