M23.42 Loose body in knee, left 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) 564-566 in MDC 08.

Approximate ICD-9-CM (GEMs)

• 717.6 Loose body in knee (approximate)

Code annotations containing back-references to M23.42

Back-references to M23.4

• Type 2 Excludes: M24.0 Loose body in joint ("loose body in knee (M23.4)")

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

• M23.362 Other meniscus derangements, other lateral meniscus, left knee
• M23.369 Other meniscus derangements, other lateral meniscus, unspecified knee
• M23.4 Loose body in knee
• M23.40 Loose body in knee, unspecified knee
• M23.41 Loose body in knee, right knee
• M23.42 Loose body in knee, left knee (this code)
• M23.5 Chronic instability of knee
• M23.50 Chronic instability of knee, unspecified knee
• M23.51 Chronic instability of knee, right knee
• M23.52 Chronic instability of knee, left knee
• M23.6 Other spontaneous disruption of ligament(s) of knee