Summary & Overview
CPT 29435: Lower Extremity Cast Application (Below Knee to Hip)
CPT code 29435 is a nationally recognized billing code for the application of a lower extremity cast, extending from below the knee to the hip, and includes the provision of a knee immobilizer or walking boot for each leg. This procedure is essential in orthopedic care for immobilizing fractures and injuries to the leg, facilitating proper healing and recovery. The code is most frequently utilized in office or outpatient settings, reflecting its role in non-emergent, ambulatory care environments.
Major payers covering this service include Aetna, Blue Cross Blue Shield, Cigna Health, Medicare, and UnitedHealthcare. Understanding coverage and reimbursement policies for CPT code 29435 is critical for providers and billing professionals, as it impacts claims processing and financial outcomes across the healthcare system.
This publication provides a comprehensive overview of CPT code 29435, including clinical context, payer coverage, and related policy updates. Readers will gain insight into national benchmarks, relevant modifiers, associated diagnoses, and related CPT codes. The analysis also highlights the importance of accurate coding and documentation for orthopedic procedures involving cast application. By reviewing this summary, stakeholders can stay informed about evolving payer requirements and industry standards for lower extremity cast application.
CPT Code Overview
CPT code 29435 describes the application of a cast to the lower extremity, specifically from below the knee to the hip level. This procedure includes the use of one knee immobilizer or walking boot for each leg. It is classified as a surgical service under the category of application of casts and strapping for the lower extremity. The typical site of service for this procedure is an office or outpatient setting, such as place of service 11. This code is commonly used in orthopedic practices to immobilize the leg following fractures or other injuries requiring stabilization.
Clinical & Coding Specifications
Clinical Context
A patient presents to the office or outpatient clinic with a closed fracture of the lower end or shaft of the tibia, or a pathological fracture of the tibia. The provider evaluates the injury and determines that immobilization is required for proper healing. The clinical workflow involves the application of a cast extending from below the knee to the hip level, which may include a knee immobilizer or walking boot for each leg. The procedure is performed by an orthopaedic surgeon or a provider with expertise in musculoskeletal injuries. The cast ensures stabilization of the fracture site and facilitates recovery, with follow-up visits scheduled to monitor healing and adjust immobilization as needed.
Coding Specifications
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Modifiers:
Modifier Code Description When to Use LTLeft side When the cast is applied to the left lower extremity RTRight side When the cast is applied to the right lower extremity -
Provider Taxonomies:
Taxonomy Code Specialty Name 2085S0701XOrthopaedic Surgery
Related Diagnoses
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S82.401A: Unspecified fracture of lower end of right tibia, initial encounter for closed fracture- Relevant for patients with a closed fracture at the lower end of the right tibia requiring immobilization.
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S82.402A: Unspecified fracture of lower end of left tibia, initial encounter for closed fracture- Indicates a closed fracture at the lower end of the left tibia, appropriate for cast application.
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S82.301A: Unspecified fracture of shaft of right tibia, initial encounter for closed fracture- Used when the fracture is located at the shaft of the right tibia and immobilization is needed.
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S82.302A: Unspecified fracture of shaft of left tibia, initial encounter for closed fracture- Applies to fractures at the shaft of the left tibia, requiring cast placement.
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M84.461A: Pathological fracture, right tibia, initial encounter for fracture- For cases where the fracture is due to underlying pathology in the right tibia, necessitating immobilization.
Related CPT Codes
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29425: Application of short leg cast (below knee to toes)- Used for immobilization of injuries below the knee, such as ankle or foot fractures. It is an alternative to
29435when the injury does not require immobilization up to the hip level.
- Used for immobilization of injuries below the knee, such as ankle or foot fractures. It is an alternative to
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29440: Lower extremity application of casts (complex or walking boot variant)- Used for more complex cast applications or when a walking boot is indicated. This code may be used in conjunction with or as an alternative to
29435depending on the complexity and clinical requirements.
- Used for more complex cast applications or when a walking boot is indicated. This code may be used in conjunction with or as an alternative to
Both 29425 and 29440 are related to 29435 in the clinical workflow, with selection based on the location and complexity of the injury. These codes are not typically used together for the same extremity but may be alternatives depending on the clinical scenario.
Coding Specifications
-
Modifiers:
Modifier Code Description When to Use LTLeft side When the cast is applied to the left lower extremity RTRight side When the cast is applied to the right lower extremity -
Provider Taxonomies:
Taxonomy Code Specialty Name 2085S0701XOrthopaedic Surgery
Related Diagnoses
-
S82.401A: Unspecified fracture of lower end of right tibia, initial encounter for closed fracture- Relevant for patients with a closed fracture at the lower end of the right tibia requiring immobilization.
-
S82.402A: Unspecified fracture of lower end of left tibia, initial encounter for closed fracture- Indicates a closed fracture at the lower end of the left tibia, appropriate for cast application.
-
S82.301A: Unspecified fracture of shaft of right tibia, initial encounter for closed fracture- Used when the fracture is located at the shaft of the right tibia and immobilization is needed.
-
S82.302A: Unspecified fracture of shaft of left tibia, initial encounter for closed fracture- Applies to fractures at the shaft of the left tibia, requiring cast placement.
-
M84.461A: Pathological fracture, right tibia, initial encounter for fracture- For cases where the fracture is due to underlying pathology in the right tibia, necessitating immobilization.
Related CPT Codes
-
29425: Application of short leg cast (below knee to toes)- Used for immobilization of injuries below the knee, such as ankle or foot fractures. It is an alternative to
29435when the injury does not require immobilization up to the hip level.
- Used for immobilization of injuries below the knee, such as ankle or foot fractures. It is an alternative to
-
29440: Lower extremity application of casts (complex or walking boot variant)- Used for more complex cast applications or when a walking boot is indicated. This code may be used in conjunction with or as an alternative to
29435depending on the complexity and clinical requirements.
- Used for more complex cast applications or when a walking boot is indicated. This code may be used in conjunction with or as an alternative to
Both 29425 and 29440 are related to 29435 in the clinical workflow, with selection based on the location and complexity of the injury. These codes are not typically used together for the same extremity but may be alternatives depending on the clinical scenario.
National Reimbursement Benchmarks
For CPT code 29435, the national mean rate for Medicare is $143.74, closely aligned with the BUCA (average commercial) mean rate of $143.84. Commercial payers such as UnitedHealth Group and Cigna report higher mean rates, at $185.50 and $179.58 respectively, while Aetna is notably lower at $86.54.
Rate dispersion, measured by the difference between the 75th and 25th percentiles, varies significantly across payers. Medicare exhibits the tightest range ($16.00), indicating relatively consistent reimbursement. In contrast, UnitedHealth Group and Cigna show the widest ranges ($105.33 and $100.00, respectively), reflecting greater variability in commercial rates. Aetna also has a narrower range ($37.23) compared to other commercial payers.
The table and chart below present a detailed breakdown of national benchmarks for each payer, including mean rates and percentile values.
Trek Health ingests and normalizes Transparency in Coverage data and payer policy updates to give provider organizations a clear view of how commercial reimbursement behaves across markets, payers, and services. Our platform transforms raw payer disclosures into structured intelligence that supports contract evaluation, payer negotiations, and service line strategy. By combining market benchmarks with ongoing policy visibility, Trek helps teams identify variability, risk, and opportunity in commercial reimbursement. The result is faster insight, stronger negotiating positions, and more informed financial decisions.