ICD-10-CM 2027 diagnosis code
M77.51Other enthesopathy of right foot and ankle
M77.51 is a valid, billable ICD-10-CM code for other enthesopathy of right foot and ankle. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.
Code last changed in FY2020 (effective October 1, 2019). Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data
About M77.51
M77.51 is the ICD-10-CM diagnosis code for other enthesopathy of right foot and ankle. It belongs to category M77 (other enthesopathies), block M70-M79 (other soft tissue disorders) 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 M77.5 (other enthesopathy of foot and ankle), M77.51 is specifically for other enthesopathy of right foot and ankle. Related codes cover unspecified foot and ankle (M77.50) and left foot and ankle (M77.52).
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 changed in FY2020 (title revised).
Before ICD-10, this condition was coded in ICD-9-CM as 726.79 (other enthesopathy of ankle and tarsus).
Notes that apply from higher levels
Instructions written at a parent level also apply to M77.51.
› From M77 Other enthesopathies
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 →- 726.79Other enthesopathy of ankle and tarsusapproximate
From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.
Code history
- 2016
- 2017
- 2018
- 2019
- 2020
- 2021
- 2022
- 2023
- 2024
- 2025
- 2026
- 2027
- FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
- FY2020 (effective 10/1/2019): Title revised — was “Other enthesopathy of right foot”
Common questions about M77.51
Is M77.51 billable?
- Yes. M77.51 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can M77.51 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict M77.51 as a principal diagnosis.
Is M77.51 a CC or MCC?
- No. M77.51 is neither a CC nor an MCC under MS-DRG v44.0.
What DRG does M77.51 group to?
- M77.51 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 M77.51?
- The CMS General Equivalence Mappings map M77.51 to ICD-9-CM 726.79.