CPT code 21423 represents an open reduction and internal fixation procedure for a complicated fracture of the maxilla (roof of the mouth or upper jaw bone). This surgical code is used when multiple incisions or approaches are required to expose and stabilize comminuted or displaced fractures of the upper jaw. Nationally, accurate use of this code matters for clinical documentation, hospital resource planning, and appropriate surgical reimbursement for high-acuity facial trauma.

Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise clinical context for when CPT code 21423 is appropriate, plus benchmarks and coding considerations relevant to facility and surgeon billing. The publication summarizes typical sites of service, common modifiers used in practice, and related billing themes for complex maxillofacial trauma care.

This resource is intended to inform coding professionals, clinicians, and revenue managers about the clinical scenario tied to CPT code 21423, common payer coverage considerations, and what to review in claim documentation to support medical necessity. Data not available in the input are listed where applicable in detailed sections.