S12.030G Displaced posterior arch fracture of first cervical vertebra, subsequent encounter for fracture with delayed healing

ICD-10-CM Code S12.030G: Displaced Posterior Arch Fracture of First Cervical Vertebra, Subsequent Encounter with Delayed Healing

ICD-10-CM code S12.030G identifies a displaced posterior arch fracture of the first cervical vertebra during a subsequent encounter for fracture with delayed healing. The first cervical vertebra, or atlas, is a ring-shaped structure lacking a vertebral body. Atlas fractures represent a small percentage of acute spine injuries and are frequently associated with motor vehicle accidents and falls. 1 3 4

Plain-language overview

The first cervical vertebra is named the atlas and is a ring-shaped structure formed by an anterior and posterior ring joined by two lateral masses, lacking a vertebral body or spinous process. Fractures of this vertebra account for approximately 10 to 13 percent of cervical spine fractures. 1

What this code represents

Code S12.030G is an ICD-10-CM diagnosis with the official label of a displaced posterior arch fracture of the first cervical vertebra, subsequent encounter for fracture with delayed healing. This specific alphanumeric designation captures both the anatomical injury and the delayed healing encounter status. 3 4

Clinical context

Atlas fractures are classified into groups that include isolated fractures of the posterior arch, combined fractures of the anterior and posterior arch, and isolated fractures of the lateral mass. The first cervical vertebra's posterior ring contains bilateral grooves where the vertebral artery and first spinal nerve travel. 1 2

Reported injury mechanisms for atlas fractures include motor vehicle accidents and falls. Management of these injuries depends on the integrity of the transverse atlantal ligament, and initial nonoperative management using external immobilization is recommended by most authors for isolated atlas fractures. 1

Documentation considerations

The official code label for S12.030G explicitly specifies a displaced posterior arch fracture of the first cervical vertebra. The documentation elements of arch location, displacement, and delayed healing status are directly embedded within the official descriptive text of this diagnosis code. 3 4

Coverage and utilization context

The Centers for Medicare and Medicaid Services includes code S12.030G within a billing and coding article for cervical fusion. The appearance of this diagnosis code in this official administrative document provides operational context for its use in healthcare billing systems. 4

What the sources add

The National Cancer Institute's EVS Explore portal provides the exact semantic concept definition and official label for S12.030G, while a separate Centers for Medicare and Medicaid Services article lists the identical code label within a cervical fusion billing document. 3 4

Clinical literature describes the anatomical features and injury mechanisms of first cervical vertebra fractures, whereas official coding sources provide the specific alphanumeric designation S12.030G to classify a subsequent encounter for delayed healing of this displaced posterior arch injury. 1 3

Sources

1. Solitary C1 Posterior Fixation for Unstable Isolated Atlas Fractures: Case Report and Systematic Review of the Literature — pmc.ncbi.nlm.nih.gov; accessed 2026-07-25.
2. Delayed diagnosis of fractured anterior arch of the atlas in a young child — pmc.ncbi.nlm.nih.gov; accessed 2026-07-25.
3. EVS Explore — evsexplore.semantics.cancer.gov; accessed 2026-07-25.
4. Article - Billing and Coding: Cervical Fusion (A59645) — cms.gov; accessed 2026-07-25.