M23.42
✓ BillableLoose body in knee, left knee
Diseases of the musculoskeletal system and connective tissue (M00-M99)
❌ Excludes1
inheritedRules inherited from parent codes in the hierarchy.
- • ankylosis (M24.66)
- • deformity of knee (M21.-)
- • osteochondritis dissecans (M93.2)
⚠️ Excludes2
inheritedRules inherited from parent codes.
- • 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)
Clinical Description
ICD-10-CM code M23.42 represents loose body in knee, left knee. This code falls under the Diseases of the musculoskeletal system and connective tissue (M00-M99) classification. It is a billable/specific code valid for HIPAA-covered transactions as of October 1, 2025 (FY2026). This code can be used to indicate a diagnosis for reimbursement purposes on insurance claims.
This is a 6-character code at the 5th level of specificity. This is the most specific code available in this subcategory. Coders should note that M23.42 has 3 Excludes1 restriction(s) — codes that cannot be reported together on the same claim.
Frequently Asked Questions
What is ICD-10 code M23.42?
ICD-10-CM code M23.42 is "Loose body in knee, left knee". It belongs to the category: Diseases of the musculoskeletal system and connective tissue (M00-M99).
Is M23.42 a billable ICD-10 code?
Yes, M23.42 is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes.
What codes are excluded with M23.42?
M23.42 has 3 Excludes1 rule(s). These codes are mutually exclusive and cannot be coded together on the same claim.
Can M23.42 be coded with other codes?
M23.42 has 3 Excludes2 note(s). These conditions can be coded together if both are documented in the patient record.
Related Codes in M23.4
Other codes in the same category that may be relevant for differential coding:
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Data Source
CMS ICD-10-CM 2026 Tabular List
Updated October 1, 2025 (FY2026)