CPT 26842 Thumb CMC Fusion Reimbursement | OpenPayer

Summary & Overview

CPT 26842: Thumb Carpometacarpal Fusion with Autologous Bone Graft

CPT code 26842 denotes surgical fusion of the thumb carpometacarpal (CMC) joint with autologous bone grafting. Nationally, this procedure is used to treat advanced thumb CMC joint arthritis, instability, or deformity when joint-preserving options are insufficient. The code reflects a definitive reconstructive technique that can reduce pain and improve function but requires operative resources, postoperative immobilization, and rehabilitation.

Key payers discussed include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Coverage policies and prior authorization practices for CMC arthrodesis vary across these payers, affecting site-of-service utilization (hospital outpatient, ambulatory surgical center, or inpatient settings) and claims processing requirements.

Readers will find clinical context for when CPT code 26842 is reported, typical sites of service, and the common care pathway surrounding thumb CMC fusion with bone graft. The publication summarizes payer coverage themes, authorization and documentation considerations, and benchmarking areas relevant to billing and utilization. Data not available in the input for specific modifiers, taxonomies, or ICD-10 pairings is noted elsewhere in the full report.

AetnaBlue Cross Blue ShieldCigna HealthUnitedHealthcareMedicareCPT 26842thumb carpometacarpal fusionhand surgerybone graftorthopedic surgeryambulatory surgery centerhospital outpatientsurgical codingarthrodesis

Billing Code Overview

CPT code 26842 describes a surgical procedure to fuse (immobilize) the carpometacarpal joint of the thumb. The surgeon stabilizes the junction between the thumb metacarpal and the trapezium bone, often creating new bone in the joint space using an autologous bone graft harvested from elsewhere in the patient’s body.

Service type: Surgical, reconstructive hand surgery

Typical site of service: Hospital outpatient or inpatient surgical suite, ambulatory surgery center

Clinical & Coding Specifications

Clinical Context

A typical patient is a 60-year-old right-hand–dominant female with chronic, symptomatic osteoarthritis of the first carpometacarpal (CMC) joint of the thumb causing severe pain, reduced pinch strength, and impaired activities of daily living despite conservative care (splinting, corticosteroid injection, NSAIDs, and occupational therapy). After clinic evaluation, imaging (X-ray) confirms advanced CMC joint collapse and subluxation. The patient is scheduled for surgical arthrodesis of the thumb CMC joint with autologous bone grafting and possible internal fixation under regional or general anesthesia.

Clinical workflow:

Preoperative evaluation: history, physical exam focused on hand function, informed consent, imaging review, and assessment of comorbidities.
Day of surgery: operative time includes exposure of the CMC joint, preparation of joint surfaces, harvest of autologous bone graft (commonly from the distal radius or iliac crest), placement of bone graft into the joint space, stable internal fixation (screws, plates, or K-wires) as indicated, and closure.
Postoperative care: immobilization in a thumb spica cast or splint, pain management, wound checks, radiographic confirmation of fixation and early graft incorporation, and staged hand therapy focused on range of motion of adjacent joints and progressive strengthening once fusion is achieved.
Typical site of service: ambulatory surgery center or hospital outpatient surgical suite. Inpatient admission may occur for complex reconstructions or significant comorbidity management.

Coding Specifications

CPT 26852: Metacarpophalangeal Joint Arthrodesis with Bone Graft

CPT-26850-METACARPOPHALANGEAL-JOINT-ARTHRODESIS

CPT 26850: Metacarpophalangeal Joint Arthrodesis

CPT-26862-INTERPHALANGEAL-JOINT-FUSION-FINGER

CPT 26862: Interphalangeal Joint Fusion of Finger

CPT-26863-INTERPHALANGEAL-JOINT-FUSION-ADD-ON

CPT 26863: Interphalangeal Joint Fusion, Additional Joint

CPT-26844-CARPOMETACARPAL-JOINT-FUSION-NONTHUMB-DIGIT

CPT 26844: Carpometacarpal Joint Fusion, Non-Thumb Digit

CPT-26841-THUMB-CARPOMETACARPAL-JOINT-ARTHRODESIS-IMMOBILIZATION

CPT 26841: Thumb Carpometacarpal Joint Immobilization

CPT-26820-THUMB-MCP-JOINT-IMMOBILIZATION-OPPOSITION-AUTOGRAFT

CPT 26820: Thumb MCP Joint Immobilization in Opposition with Autograft

CPT-26861-ADD-ON-INTERPHALANGEAL-JOINT-ARTHRODESIS

CPT 26861: Add‑on Interphalangeal Joint Arthrodesis

CPT-26860-INTERPHALANGEAL-JOINT-ARTHRODESIS-IMMOBILIZATION

CPT 26860: Interphalangeal Joint Immobilization (Arthrodesis)

CPT-26843-CARPOMETACARPAL-JOINT-FUSION-DIGIT-OTHER-THAN-THUMB

CPT 26843: Carpometacarpal Joint Fusion, Digit Other Than Thumb

`26`	Professional component	Use when reporting only the surgeon’s professional component separate from the technical facility charge if applicable in split-billing arrangements.
`50`	Bilateral procedure	Use when arthrodesis is performed on both right and left thumb CMC joints during the same operative session.
`51`	Multiple procedures	Use when additional distinct procedures are performed during the same operative session (report primary code first, then append `51` to secondary codes as payer policy requires).
`52`	Reduced services	Use when the procedure is intentionally partially reduced or not completed as described (e.g., limited exposure or incomplete grafting).
`53`	Discontinued procedure	Use when the procedure is started but discontinued due to extenuating circumstances or patient safety (document reason).
`62`	Two surgeons	Use when two surgeons work together as primary surgeons performing distinct portions of the procedure (co-surgery).
`66`	Surgical team	Use when a surgical team model is used and multiple surgeons from different specialties are billing under a team approach, per payer rules.
`78`	Unplanned return to OR	Use when the patient returns to the operating room for the same surgical site for a related procedure during the global period.
`79`	Unrelated procedure or service during postoperative period	Use when an unrelated procedure is performed during the global period (not directly listed in provided modifiers but commonly relevant; if not allowed by payer omit).
`LT`	Left side	Use to indicate the procedure was performed on the left thumb.
`RT`	Right side	Use to indicate the procedure was performed on the right thumb.
`53`	Discontinued procedure	Use when the procedure is terminated prior to completion for patient safety or other documented reasons.
`22`	Unusual procedural services	Use when the work required to perform the procedure is substantially greater than typically required (must be well documented).
`23`	Unusual anesthesia	Use when general anesthesia is required due to a medically necessary circumstance in a procedure typically performed with regional or local anesthesia.

Taxonomy Code	Specialty	Notes
207VG0500X	Orthopedic Surgery	Most common specialty performing thumb CMC arthrodesis and bone grafting.
207XS0103X	Hand Surgery	Surgeons with fellowship training in hand surgery frequently perform this procedure.
2080P0207X	Plastic and Reconstructive Surgery	Plastic surgeons with hand surgery expertise may perform complex reconstructions including CMC arthrodesis.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`M18.0`	Primary osteoarthritis of first carpometacarpal joint	Most common indication for thumb CMC arthrodesis when conservative therapy fails.
`M18.11`	Osteoarthritis, right first carpometacarpal joint	Side-specific code used when documenting laterality for right thumb surgery.
`M18.12`	Osteoarthritis, left first carpometacarpal joint	Side-specific code used when documenting laterality for left thumb surgery.
`M18.9`	Osteoarthritis of first carpometacarpal joint, unspecified	Used when laterality is not specified or unknown.
`M21.611`	Deformity, acquired, right hand	May apply when deformity contributes to symptomatic dysfunction requiring arthrodesis.
`S63.501A`	Sprain of right thumb, initial encounter	Used when prior acute injury with persistent instability leads to fusion.
`M24.511`	Recurrent dislocation, right shoulder (example placeholder)	Data not available in the input.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`26840`	Repair, tendon sheath, or pulley (not directly related)	Data not available in the input.
`20930`	Allograft, morselized, or placement of osteopromotive material	May be used if bone graft substitute or allograft is used instead of autograft during CMC arthrodesis.
`20680`	Removal of implant; deep (e.g., after fusion)	Performed if deep hardware removal is required after consolidation or for complication management.
`64718`	Neuroplasty and/or transposition; median nerve at carpal tunnel	Carpal tunnel procedures may be performed concomitantly in patients with symptomatic median neuropathy; report separately if performed.
`11010`	Incision and removal of foreign body or superficial bone graft harvest	Represents small-site graft harvest techniques (site-specific codes vary); used when autologous graft is harvested from a separate anatomic site.

OpenPayer