Is a muscle flap code (15734) with fusion medically necessary for a patient with juvenile idiopathic scoliosis and a Cobb angle of 59 degrees?

Medical Necessity Determination for CPT 15734 (Muscle Flap) with Fusion

CPT code 15734 is NOT medically necessary for this patient and should be DENIED. The code 15734 refers to muscle flap procedures, but the clinical documentation describes a standard posterior spinal fusion (PSF) for juvenile idiopathic scoliosis without any indication for muscle flap coverage.

Critical Code Misidentification

• CPT 15734 is a muscle, myocutaneous, or fasciocutaneous flap code used for trunk reconstruction, NOT a standard component of posterior spinal fusion for idiopathic scoliosis 1
• The GRG criteria cited references vertebral body tethering (a growth-modulating procedure), which is completely different from the posterior spinal fusion being requested 1
• The patient does NOT meet criteria for vertebral body tethering - she is Risser 4 (nearly skeletally mature), whereas tethering requires skeletally immature patients with flexible curves 1

Medical Necessity for Posterior Spinal Fusion (The Actual Procedure)

The posterior spinal fusion itself IS medically necessary and meets all established criteria:

Aetna CPB Criteria - FULLY MET

• Curve magnitude: 59 degrees in a 15-year-old patient with juvenile idiopathic scoliosis clearly exceeds the 40-degree threshold for surgical intervention in patients under age 18 1, 2
• Conservative management with bracing was attempted and failed, with documented curve progression from 56 to 59 degrees 3
• The patient is skeletally immature (Risser 4) with documented progression, placing her at high risk for continued worsening 2

Supporting Surgical Indications

• Thoracic curves >50 degrees continue to progress at approximately 1 degree per year even after skeletal maturity, making intervention at 59 degrees clearly indicated 1, 2
• The patient demonstrates significant hypokyphosis and loss of lumbar lordosis, which are additional structural concerns requiring correction 1
• Documented progression despite bracing represents failed conservative management 3

Appropriate CPT Codes for This Case

The following codes ARE medically necessary based on the documentation:

• 22804 (Posterior arthrodesis, thoracic) - Primary fusion procedure for thoracic scoliosis >40 degrees 1
• 22216 x2 (Osteotomy, posterior approach) - Covered when selection criteria met per Aetna CPB 0398 1
• 22848 (Pelvic fixation) - Covered when selection criteria met per Aetna CPB 0398 1
• 22844 (Pedicle screw instrumentation) - May be certified with any spinal fusion meeting criteria 4
• 20930 (Allograft) - Medically necessary for spinal fusion, 100% bone materials covered regardless of shape 1
• 20936 (Autograft) - Medically necessary component when fusion criteria met 1

Clinical Rationale Summary

• This 15-year-old female has juvenile idiopathic scoliosis with a 59-degree right thoracic curve and 43-degree left lumbar curve 1, 2
• She is Risser 4 (nearly mature but not complete), placing her in the critical window where surgical intervention prevents lifelong progression 2
• Bracing failed to control progression (56→59 degrees), fulfilling conservative management requirements 3
• The curve magnitude, patient age, skeletal immaturity, and documented progression all support surgical necessity 1, 2

Common Pitfall Avoided

• Do not confuse muscle flap codes (15734) with standard spinal fusion procedures - muscle flaps are indicated for wound coverage in complex cases with infection, prior failed surgery, or significant soft tissue defects, NONE of which apply here 1
• The GRG criteria reference to vertebral body tethering is irrelevant - this patient is too skeletally mature for tethering and requires definitive fusion 1

Final Determination

APPROVE: Posterior spinal fusion with instrumentation (22804,22216,22848,22844,20930,20936) - 3 inpatient days per MCG criteria

DENY: CPT 15734 (muscle flap) - Not medically indicated for standard idiopathic scoliosis fusion