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ICD-10-CM 2027 diagnosis code

M66.145Rupture of synovium, left finger(s)

✓ Billable / specific

M66.145 is a valid, billable ICD-10-CM code for rupture of synovium, left finger(s). It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About M66.145

M66.145 is the ICD-10-CM diagnosis code for rupture of synovium, left finger(s). It belongs to category M66 (spontaneous rupture of synovium and tendon), block M65-M67 (disorders of synovium and tendon) and chapter 13 (diseases of the musculoskeletal system and connective tissue). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within M66.14 (rupture of synovium, hand and fingers), M66.145 is specifically for rupture of synovium, left finger(s). Related codes cover right hand (M66.141), left hand (M66.142), unspecified hand (M66.143), right finger(s) (M66.144) and unspecified finger(s) (M66.146).

It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.

In MS-DRG v44.0, it is part of the grouping logic for DRG 557 (Tendonitis, Myositis and Bursitis with MCC, relative weight 1.489) and DRG 558 (Tendonitis, Myositis and Bursitis without MCC, relative weight 0.8875), in MDC 08 (Diseases and Disorders of the Musculoskeletal System and Connective Tissue), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 727.59 (other rupture of synovium).

Notes that apply from higher levels

Instructions written at a parent level also apply to M66.145.

› From M66.1 Rupture of synovium
Excludes2
  • rupture of popliteal cyst (M66.0)
› From M66 Spontaneous rupture of synovium and tendon
Includes
  • rupture that occurs when a normal force is applied to tissues that are inferred to have less than normal strength
Excludes2
  • rotator cuff syndrome (M75.1-)
  • rupture where an abnormal force is applied to normal tissue - see injury of tendon by body region

Broader instructions also apply from Chapter 13: Diseases of the musculoskeletal system and connective tissue.

MS-DRG v44.0 grouping

All DRGs →

Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.

MDC 08 · Diseases and Disorders of the Musculoskeletal System and Connective Tissue

ICD-9-CM equivalent

Converter →
  • 727.59Other rupture of synoviumapproximate

From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about M66.145

Is M66.145 billable?

Yes. M66.145 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can M66.145 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict M66.145 as a principal diagnosis.

Is M66.145 a CC or MCC?

No. M66.145 is neither a CC nor an MCC under MS-DRG v44.0.

What DRG does M66.145 group to?

M66.145 is used in the MS-DRG v44.0 logic for MS-DRG 557 (Tendonitis, Myositis and Bursitis with MCC) and MS-DRG 558 (Tendonitis, Myositis and Bursitis without MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.

What is the ICD-9 code for M66.145?

The CMS General Equivalence Mappings map M66.145 to ICD-9-CM 727.59.