2027 ICD-10-CM Diagnosis Code M71.22Synovial cyst of popliteal space [Baker], left knee
ICD-10-CM Codes›M00–M99›M70-M79›M71
- Billable — Valid for Submission
- Not Chronic
M71.22 is a billable ICD-10-CM diagnosis code for synovial cyst of popliteal space [Baker], left knee. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 557 through 558. Coders also document this condition as mass of bilateral knee joints. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Tendon and synovial disorders.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Mass of bilateral knee joints
- Synovial cyst of bilateral knees
- Synovial cyst of left knee
- Synovial cyst of right knee
- Synovial popliteal cyst
- Synovial popliteal cyst of bilateral knees
- Synovial popliteal cyst of left knee
- Synovial popliteal cyst of right knee
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to M71.22: its own notes plus those printed at M71.2, M71, and Chapter 13. A note printed at a category, block or chapter applies to every code under it.
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
- synovial cyst of popliteal space with rupture (M66.0)
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- arthropathic psoriasis (L40.5-)
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- compartment syndrome (traumatic) (T79.A-)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
Notes
General instructions on how these codes are used.
- Use an external cause code following the code for the musculoskeletal condition, if applicable, to identify the cause of the musculoskeletal condition
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name M71.22, its category, or a range that includes it.
Excludes2 2
These codes carry an Excludes2 note naming M71.22: its condition is not part of those codes, and both may be reported when the patient has both.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Knee Injuries and Disorders
Your knee joint is made up of bone, cartilage, ligaments and fluid. Muscles and tendons help the knee joint move. When any of these structures is hurt or diseased, you have knee problems. Knee problems can cause pain and difficulty walking.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert M71.22 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About M71.22Overview
What is the ICD-10 code for synovial cyst of popliteal space [Baker], left knee?
The ICD-10-CM code for synovial cyst of popliteal space [Baker], left knee is M71.22 (sometimes written as M7122). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is M71.22 (Synovial cyst of popliteal space [Baker]) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report synovial cyst of popliteal space [Baker], left knee on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does M71.22 group to?
When synovial cyst of popliteal space [Baker], left knee is the principal diagnosis on an inpatient stay, it groups to MS-DRG 557, 558, with relative weights from 0.8873 to 1.4883 depending on complications. Higher weights mean higher Medicare reimbursement.
Can M71.22 be reported with M66.0?
Not as a rule. The Excludes1 note at M71.2, which applies to M71.22, lists "synovial cyst of popliteal space with rupture (M66.0)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
What is the ICD-9 equivalent of M71.22?
Under the General Equivalence Mappings, synovial cyst of popliteal space [Baker], left knee converts to ICD-9-CM 727.51 (popliteal synovial cyst). The mapping is approximate, so confirm the match fits the documentation.
