CPT code 27330 denotes an open synovial biopsy of the knee performed via incision over the joint to obtain synovial tissue for diagnostic evaluation. This surgical diagnostic procedure is clinically important for diagnosing inflammatory, infectious, or neoplastic processes of the knee when less-invasive sampling is inadequate. Nationally, accurate coding and clinical documentation for synovial biopsy affect coverage determinations, site-of-service decisions, and resource utilization in both outpatient surgical centers and hospitals.

Key payers commonly involved in coverage and claims for this procedure include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of the clinical context of the procedure, typical sites of service, and the payers addressed in the analysis. The publication also summarizes common billing themes and highlights benchmarks and policy considerations relevant to reimbursement and claim adjudication across major national payers. The material is intended for billing professionals, practice managers, and clinical staff seeking clarity on coding, documentation expectations, and payer coverage patterns for knee synovial biopsy.