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CPT 27599: Unlisted Procedure for Femur or Knee Surgery
CPT code 27599 is an unlisted procedure code for surgical operations on the femur or knee when no specific CPT descriptor exists. It functions as a catch-all for atypical, complex, or novel orthopaedic procedures and is important nationally because it enables reporting and reimbursement for clinically necessary services that fall outside standard code sets. Use of an unlisted code typically requires supplementary documentation to explain the procedure, rationale, and resources used.
Key payers in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will learn how CPT code 27599 is positioned within orthopaedic surgical billing, the clinical contexts that commonly prompt its use (including femoral fractures and knee pathology), and how it relates to commonly reported procedures. The publication reviews benchmarks for utilization, typical documentation expectations, and policy considerations that affect payer adjudication of unlisted femur/knee procedures.
This resource provides clinicians, billing professionals, and policy analysts with a concise reference on clinical scope, expected sites of service, and the role of CPT code 27599 within the broader orthopaedic procedure landscape. Data not available in the input includes payer-specific reimbursement amounts and individual payor policy language.
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Billing Code Overview
CPT code 27599 is an unlisted procedure code used to report surgical procedures on the femur or knee that do not have a specific CPT descriptor. This code captures atypical or novel operative techniques and complex reconstructions of femoral or knee structures when no existing CPT code accurately describes the service.
Service Type: Surgical — Orthopaedic procedures on femur or knee
Typical Site of Service: Hospital inpatient or outpatient surgical suite, ambulatory surgery center, or other operative setting
National Reimbursement Benchmarks
Commercial national rates for CPT 27599 cluster around BUCA’s average commercial benchmark of $1,633.60, with substantial variation among major payers. Blue Cross Blue Shield shows extreme high-end outliers (max $63,000) and a median at $231.50, while Aetna’s central tendency (median $1,136.10) sits near BUCA’s average. Cigna’s median of $680 and UnitedHealth Group’s median of $698 are lower than the BUCA mean, and BUCA’s own median of $491.50 indicates skewed distributions across insurers.
Dispersion measured as P75 minus P25 highlights which payers are tightest or widest: Aetna’s interquartile range is $2,931.20 − $672.00 = $2,259.20, Blue Cross Blue Shield’s IQR is $302.80 − $216.00 = $86.80 (the tightest), Cigna’s IQR is $1,292.10 − $508.00 = $784.10, UnitedHealth Group’s IQR is $1,535.10 − $252.30 = $1,282.80, and BUCA’s IQR is $995.70 − $328.00 = $667.70. Blue Cross Blue Shield therefore appears the tightest in the middle 50% while Aetna shows the widest middle spread.