S44.40XAInjury of musculocutaneous nerve, unspecified arm, initial encounter

S44.40XA is the ICD-10-CM diagnosis code for injury of musculocutaneous nerve, unspecified arm, initial encounter. It belongs to category S44 (injury of nerves at shoulder and upper arm level), block S40-S49 (injuries to the shoulder and upper arm) and chapter 19 (injury, poisoning and certain other consequences of external causes). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

The 7th character "A" means initial encounter: use it while the patient is receiving active treatment for the condition.

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 073 (Cranial and Peripheral Nerve Disorders with MCC, relative weight 1.5779), DRG 074 (Cranial and Peripheral Nerve Disorders without MCC, relative weight 1.0173), DRG 963 (Other Multiple Significant Trauma with MCC, relative weight 2.6363), DRG 964 (Other Multiple Significant Trauma with CC, relative weight 1.4972) and DRG 965 (Other Multiple Significant Trauma without CC/MCC, relative weight 1.0059), in MDC 01 (Diseases and Disorders of the Nervous System) and MDC 24 (Multiple Significant Trauma), 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 hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 955.4 (injury to musculocutaneous nerve).