S12.040BDisplaced lateral mass fracture of first cervical vertebra, initial encounter for open fracture

S12.040B is the ICD-10-CM diagnosis code for displaced lateral mass fracture of first cervical vertebra, initial encounter for open fracture. It belongs to category S12 (fracture of cervical vertebra and other parts of neck), block S10-S19 (injuries to the neck) 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 "B" means initial encounter for open fracture: use it while the patient is receiving active treatment for the condition.

Code first: any associated cervical spinal cord injury (S14.0, S14.1-).

As a secondary diagnosis it is an MCC (major complication or comorbidity), which can move an inpatient stay into the highest-paying "with MCC" MS-DRG of its family, unless the principal diagnosis excludes it.

In MS-DRG v44.0, it is part of the grouping logic for DRG 551 (Medical Back Problems with MCC, relative weight 1.6358), DRG 552 (Medical Back Problems without MCC, relative weight 0.9584), 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 08 (Diseases and Disorders of the Musculoskeletal System and Connective Tissue) 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 805.11 (open fracture of first cervical vertebra).