CPT 27100: External Oblique Transfer to Greater Trochanter
CPT code 27100 represents a surgical muscle-transfer procedure in which the external oblique is repositioned to the greater trochanter to restore hip abductor function in patients with paralysis. This reconstructive orthopedic technique is clinically important for improving gait stability and reducing Trendelenburg gait in affected patients. Nationally, the procedure is performed in specialized orthopedic and reconstructive surgery programs and may have implications for postoperative rehabilitation and long-term functional outcomes.
Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find an overview of the clinical context and typical sites of service, plus what payers commonly consider when evaluating coverage for complex reconstructive procedures. The publication summarizes available benchmarks where present, highlights relevant policy considerations affecting authorization and post-operative care, and outlines the clinical rationale for the procedure.
This summary is intended for clinicians, coding and billing professionals, and policy analysts seeking a concise briefing on CPT code 27100, including its clinical purpose, service setting, and the payer landscape that typically influences access and reimbursement processes.
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Billing Code Overview
CPT code 27100 describes a surgical procedure in which the provider transfers the external oblique muscle to the greater trochanter to compensate for paralyzed hip abductor muscles. The external oblique is the largest and most superficial muscle of the anterior abdominal wall.
Service Type: Surgical, muscle transfer for hip abductor reconstruction
Typical Site of Service: Inpatient or outpatient surgical setting (operating room)
Clinical & Coding Specifications
Clinical Context
A typical patient is an adult with chronic paralysis or severe weakness of the hip abductor mechanism (gluteus medius/minimus) after traumatic nerve injury, poliomyelitis sequelae, or iatrogenic sciatic nerve damage. The patient presents with a Trendelenburg gait, lateral hip instability, and pain or functional limitation despite conservative management (physical therapy, orthoses). Preoperative workup includes gait analysis, pelvic radiographs, MRI or electromyography to confirm abductor deficiency, and medical clearance.
In the operating room, an orthopedic or reconstructive surgeon performs a transfer of the external oblique muscle attachment to the greater trochanter to reconstitute lateral hip stability. The procedure typically requires general anesthesia, possible regional block for postoperative analgesia, and perioperative antibiotics. Postoperative care involves protected weight bearing, physical therapy for progressive strengthening, and routine wound and neurovascular checks. Follow-up visits include wound assessment, range-of-motion evaluation, and functional outcome assessments over months to determine gait improvement.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
22 | Increased procedural services | Use if work, time, or technical effort is substantially greater than typical for 27100. |
23 | Unusual anesthesia | Use when operation is performed under general anesthesia because local/regional is contraindicated and anesthesia is unusual for the procedure. |
26 | Professional component | Use when reporting separately the physician professional interpretation or service component if applicable (rare for 27100). |
50 | Bilateral procedure | Use when both hips are addressed during the same operative session. |
51 | Multiple procedures | Use when 27100 is one of multiple distinct procedures performed during the same operative session. |
52 | Reduced services | Use when the service was partially reduced or not completed as described. |
53 | Discontinued procedure | Use if the procedure is started but discontinued due to extenuating circumstances. |
62 | Two surgeons | Use when two surgeons work together as primary surgeons on the procedure. |
63 | Procedure performed on infants less than 4 kg | Use when applicable to very small pediatric patients (rare). |
80 | Assistant surgeon | Use when a qualified assistant performs portions of the procedure. |
81 | Minimum assistant surgeon | Use when a minimal assistant is required. |
82 | Assistant surgeon (when qualified resident not available) | Use when no qualified resident is available and an assistant is needed. |
78 | Return to OR for related procedure during postoperative period | Use when a related operative procedure is required during the global period. |
| Taxonomy Code | Specialty | Notes |
|---|---|---|
| 207L00000X | Orthopedic Surgery | Primary specialty performing muscle transfer for hip abductor deficiency. |
| 2080P0222X | Physical Medicine & Rehabilitation | Manages preoperative functional assessment and postoperative rehab. |
| 2086S0122X | Reconstructive Plastic Surgery | Performs soft tissue transfers or complex reconstructions when indicated. |
| 207K00000X | Neurological Surgery | Consulted when procedure relates to nerve injury management and reconstruction. |
Related Diagnoses
| ICD-10 Code | Description | Clinical Relevance |
|---|---|---|
G83.4 | Monoplegia of lower limb | Hip abductor paralysis requiring muscle transfer to restore lateral stability. |
G82.50 | Paraplegia, unspecified | When abductor dysfunction is part of broader lower-extremity paralysis impacting gait. |
M62.81 | Muscle weakness (generalized) | Localized severe abductor weakness may be an indication when focal. |
S34.0X9 | Unspecified injury of nerve root of lumbar and sacral spinal cord segment | Nerve injuries causing abductor paralysis that necessitate tendon/muscle transfer. |
M16.9 | Osteoarthritis of hip, unspecified | Secondary abductor insufficiency may accompany degenerative hip disease influencing surgical planning. |
Related CPT Codes
| CPT Code | Description | Relationship to This Procedure |
|---|---|---|
20680 | Removal of implant; deep (e.g., buried wire, pin, screw, metal band, nail, rod or plate) | Performed if prior hardware removal is necessary before muscle transfer. |
27020 | Fasciotomy, hip region (e.g., compartment syndrome) | May be used when decompression of fascial compartments is required as part of exposure or management. |
27030 | Arthrotomy, hip; with biopsy | Performed if intra-articular inspection or biopsy is needed during the operative session. |
27096 | Open treatment of pelvic fracture, posterior ring, with internal fixation | Relevant when hip abductor deficiency follows pelvic fracture requiring concurrent stabilization. |
29827 | Arthroscopy, hip, surgical; with synovectomy, debridement/loose body removal (separate procedure) | Sometimes performed arthroscopically prior to or after open soft-tissue reconstruction when intra-articular pathology coexists. |