M23.021 Cystic meniscus, posterior horn of medial meniscus, right knee

Billable ICD-10-CM code, FY2026.

Applies from M23 Internal derangement of knee

Excludes1 (never code together)

• ankylosis (M24.66)
• deformity of knee (M21.-)
• osteochondritis dissecans (M93.2)

Excludes2 (not included here)

• current injury - see injury of knee and lower leg (S80-S89)
• recurrent dislocation or subluxation of joints (M24.4)
• recurrent dislocation or subluxation of patella (M22.0-M22.1)

MS-DRG index

Defines the logic of DRG(s) 562-563 in MDC 08.

Approximate ICD-9-CM (GEMs)

• 717.2 Derangement of posterior horn of medial meniscus (approximate)

Code annotations containing back-references to M23.021

Back-references to M23

• Type 2 Excludes: M24.1 Other articular cartilage disorders ("internal derangement of knee (M23.-)")
• Type 2 Excludes: S83 Dislocation and sprain of joints and ligaments of knee ("internal derangement of knee (M23.-)")

Nearby codes

• M23.01 Cystic meniscus, anterior horn of medial meniscus
• M23.011 Cystic meniscus, anterior horn of medial meniscus, right knee
• M23.012 Cystic meniscus, anterior horn of medial meniscus, left knee
• M23.019 Cystic meniscus, anterior horn of medial meniscus, unspecified knee
• M23.02 Cystic meniscus, posterior horn of medial meniscus
• M23.021 Cystic meniscus, posterior horn of medial meniscus, right knee (this code)
• M23.022 Cystic meniscus, posterior horn of medial meniscus, left knee
• M23.029 Cystic meniscus, posterior horn of medial meniscus, unspecified knee
• M23.03 Cystic meniscus, other medial meniscus
• M23.031 Cystic meniscus, other medial meniscus, right knee
• M23.032 Cystic meniscus, other medial meniscus, left knee