Orthopedic Billing: Global Periods, Joint Injections, and Assistant Surgeon Rules in 2026

Why Orthopedic Billing Is Different

Orthopedic practices bill across an unusually wide procedural spectrum in a single episode of care: an evaluation and management visit, in-office imaging, a joint injection, a cast or splint application, durable medical equipment, and potentially a 90-day global surgical package, all for the same patient within a short window. Unlike primary care, where the E/M visit is the dominant billing unit, orthopedics generates dense stacks of CPT codes per encounter, each with its own bundling relationship to the others. The 90-day global surgical period, which applies to most major orthopedic procedures including joint replacement, fracture fixation, and spine surgery, bundles all related pre-operative, intra-operative, and post-operative E/M visits into a single payment, so distinguishing a related follow-up from an unrelated new problem in the same patient becomes a persistent coding and documentation exercise that most other specialties do not face at this scale.

The specialty also carries a heavy DME and supply billing component that most surgical specialties do not manage in-house. Braces, splints, and other orthotic devices span both L-codes (orthotics and prosthetics under the HCPCS Level II L-code series) and A-codes (medical supplies), and choosing the wrong code family, or billing a DME item without a signed physician order and proof of delivery, is a frequent and entirely preventable denial source. Practices also administer high volumes of joint and soft tissue injections that pair a procedure code with a drug HCPCS code, mirroring the two-line billing complexity seen in specialties like ophthalmology, but multiplied across a wider range of joint sizes (small, intermediate, and large) with corresponding CPT code tiers.

Spine and complex joint surgery introduce a further layer of complexity around assistant surgeon and co-surgeon billing that primary care and even many other surgical specialties rarely encounter. Modifiers 80, 81, 82, and AS each describe a different assistant-at-surgery scenario, and Medicare's own payment policy indicators determine whether an assistant is payable at all for a given procedure code, independent of medical necessity. Getting this modifier selection wrong, or omitting required documentation showing why a resident was not available, is a common and specialty-specific denial driver per CMS Medicare Claims Processing Manual, Pub. 100-04, Transmittal R1620CP.

Finally, orthopedics sits close to workers' compensation, auto liability, and high-deductible commercial plans more than most specialties, which adds payer-specific authorization and documentation rules on top of standard Medicare policy. MRI prior authorization denials are especially common because many payers require documented conservative treatment, such as a defined course of physical therapy, NSAIDs, or injections, before approving advanced imaging, and orthopedic practices must track and submit this history proactively rather than reactively after a denial per MedPrecision Billing orthopedic billing guidance.

The 2026 Policy and NCCI Landscape for Orthopedics

CMS Physician Fee Schedule and RVU Changes

The CY 2026 Medicare Physician Fee Schedule final rule (CMS-1832-F), effective January 1, 2026, set two conversion factors: $33.5675 for qualifying APM participants and $33.4009 for non-qualifying participants, increases of 3.77% and 3.26% respectively from the CY 2025 conversion factor of $32.3465. CMS also finalized a 2.5% efficiency adjustment reduction to work RVUs and the corresponding intra-service time for nearly all non-time-based procedural and diagnostic codes, based on a five-year lookback at the Medicare Economic Index productivity adjustment. Time-based codes, E/M visits, and new CY 2026 codes were exempted.

For orthopedics, an AMGA analysis of the final rule estimates the overall weighted impact of the efficiency adjustment is close to a 1.5% decrease in work RVUs for orthopedic providers, concentrated in procedural and imaging-heavy codes rather than E/M services. CMS additionally finalized a change to indirect practice expense allocation for facility-based services, reducing the portion of indirect practice expense allocated by work RVU to 50% of the non-facility amount beginning in 2026, which disproportionately affects hospital-based and ambulatory surgical center orthopedic procedures compared to office-based evaluation and injection services.

NCCI Edits and Global Surgery Policy

Orthopedic global surgical packages, generally 90 days for major procedures such as joint replacement, fracture fixation, and spine surgery, and 0 or 10 days for many injections and minor procedures, continue to bundle related E/M visits, casting, and follow-up imaging under Medicare Global Surgery rules in the Medicare Claims Processing Manual, Pub. 100-04, Chapter 12. Assistant-at-surgery billing (modifiers 80, 81, 82, and AS) is governed by a payment policy indicator assigned to each CPT code. Medicare denies assistant surgeon claims outright for codes with a policy indicator of 0 using CARC 54 (multiple physicians/assistants are not covered in this case), regardless of documentation, while codes with indicator 1 require documented medical necessity or an exceptional circumstance, such as a stated across-the-board policy of not involving residents.

Prior Authorization Trends

MRI prior authorization remains one of the highest-friction utilization management categories in orthopedics. A 2023 prospective study published in the journal Orthopedics found that nearly all peer-to-peer reviews for CT and MRI prior authorization denials in orthopedic practices resulted in approval on appeal, indicating that many initial denials are overturned once a physician-to-physician conversation occurs, per Muni Health's peer-to-peer review guide. Commercial payers, including major Blue Cross Blue Shield plans, increasingly require documented conservative treatment, typically a defined period of physical therapy, NSAIDs, and/or injections, before authorizing joint replacement and advanced imaging, and deny claims when that history is not explicitly included in the authorization request.

AAOS Coding Resources

The American Academy of Orthopaedic Surgeons maintains a formal Coding, Coverage, and Reimbursement Committee (CCRC) that publishes the Complete Global Service Data for Orthopaedic Surgery, an annually updated reference covering more than 1,700 procedures with bundling rules, NCCI edit guidance, and global period documentation, alongside the Orthopaedic Code-X platform and Musculoskeletal Coding Guide, both updated for 2026 per AAOS Now and the AAOS coding and reimbursement resources. AAOS also publishes prior authorization tip sheets and appeal letter templates specifically for orthopedic denials, reflecting how central prior auth and global period disputes are to the specialty's revenue cycle.

Top 6 Orthopedic Denial Patterns in 2026

Orthopedic practices tend to see the same denial patterns repeatedly. Knowing the root cause behind each code, rather than just the code itself, is what separates a practice with a single-digit denial rate from one writing off a substantial share of gross charges. Here are the six most consistent patterns, with the CARC codes typically attached and the fastest path to resolution.

1. E/M Visit During the Global Surgical Period Billed Without Modifier 24 (CARC 97)

CARC 97 (the benefit for this service is included in the payment/allowance for another service/procedure that has already been adjudicated) and RARC M144 (pre/post-operative care is included in the allowance for the surgery/procedure) appear when a patient returns during the global period of a joint replacement for an unrelated condition, such as a new shoulder complaint, but the visit is billed without modifier 24, or the documentation does not clearly separate the unrelated diagnosis from the surgical diagnosis. Medicare's 90-day global surgical period bundles all related follow-up care into the original surgical payment. Without modifier 24 and a clearly unrelated diagnosis, the payer's system automatically treats the E/M visit as part of the bundled global package. AAPC compliance audits show roughly 30% of orthopedic E/M denials during global periods stem from missing modifier 24 per MedPrecision Billing analysis. Track global period start and end dates by patient and procedure in the practice management system, and require documentation that explicitly states the visit reason is unrelated to the surgical diagnosis, with a distinct ICD-10 code.

2. Joint Injection Billed With E/M Visit Missing Modifier 25 (CARC 97, CARC 4)

CARC 97 (bundled with another service) and CARC 4 (modifier missing or inconsistent with the procedure code) appear when a physician performs a scheduled injection (CPT 20610 or 20611 for a large joint, 20605 or 20606 for an intermediate joint, 20600 or 20604 for a small joint) and also bills an E/M visit on the same day without appending modifier 25, or the documentation does not show a separately identifiable, medically necessary evaluation beyond the routine work of the injection itself. Payers bundle the pre-injection assessment into the injection code by default. Modifier 25 is required to unbundle a significant, separately identifiable E/M service, and if the visit was scheduled solely for the injection with no separate exam performed, the E/M should not be billed at all per AAPC guidance on joint injection modifier 25. Document a distinct history, exam, and medical decision-making component for the E/M portion, separate from the injection procedure note.

3. Injection Procedure and Drug J-Code Bundling or Missing Units (CARC 97, CARC 16)

CARC 97 (bundled with another service already adjudicated) and CARC 16 (missing/incomplete/invalid information) appear when a large joint injection (20610, 20611) is billed with the drug supply code (J3301 triamcinolone acetonide, J-codes for hyaluronic acid derivatives such as J7325) but the units reported do not match the documented dosage, or the payer's policy bundles the drug into the injection procedure code for that specific product. Drug unit calculations must match the HCPCS descriptor exactly. If J3301 is defined per 10 mg and 40 mg was administered, 4 units must be billed. Payer-specific policies vary on whether certain hyaluronic acid products are separately payable versus bundled, particularly for Medicare Advantage plans applying step therapy or product-specific coverage limits. Build a unit-conversion reference table for every injectable drug, cross-checked against the current HCPCS descriptor.

4. Fracture Care Billed as a Global Package Without Qualifying Restorative Treatment (CARC 97, CARC 16)

CARC 97 (bundled with another service) and CARC 16 (missing/incomplete/invalid information) appear when a physician bills a global fracture care code (for example, the 25600 to 25680 forearm/wrist fracture series) for a patient who received only a splint or cast, with no reduction or manipulation performed, and without an established plan for the same physician to provide all subsequent fracture care. CMS, CPT, AAOS, and the American College of Emergency Physicians agree that a global fracture care code should only be reported when the physician performs restorative treatment, meaning a reduction or manipulation, or when the physician will provide the full global package of follow-up care. Simply applying a splint or cast without either of those conditions should be billed as an E/M visit plus the cast/strapping application code instead per AAPC guidance on ED fracture care. Document explicitly whether a reduction or manipulation was performed and whether the treating physician intends to provide all subsequent fracture care, before selecting between a global fracture code and an E/M-plus-casting approach.

5. Casting and Strapping Bundled Without Modifier 58 for Replacement Casts (CARC 97, CARC 50)

CARC 97 (bundled with another service) and CARC 50 (medical necessity) appear when a cast is replaced during the 90-day global period of a fracture care procedure due to normal wear, and the replacement is billed without modifier 58, or without documented medical necessity such as damage, loss of fit, or contamination risk. NCCI edits bundle casting and strapping (CPT 29075, 29125, 29280) into fracture care codes broadly. While a replacement cast performed during the global period can be billed separately with modifier 58 and a supporting diagnosis, payers will not reimburse a cast change performed simply because the patient did not like the appearance of the original cast. Medical necessity, such as risk of infection or loss of structural integrity, must be documented per AAPC casting NCCI edit guidance. Only the initial cast, splint, or strapping application at the time of initial fracture treatment is inherently bundled. Replacement casts performed later are separately reportable when medically necessary.

6. Assistant Surgeon or Co-Surgeon Denied for Spine and Complex Joint Procedures (CARC 54, CARC 236)

CARC 54 (multiple physicians/assistants are not covered in this case) and CARC 236 (procedure or modifier combination not compatible) appear when a spine surgeon bills for an assistant surgeon on a procedure code that carries a Medicare payment policy indicator prohibiting assistant-at-surgery payment, or bills modifier 62 (co-surgeon) on a code where the payer's policy indicator does not permit co-surgery. Common code examples include 63030 (lumbar laminotomy/discectomy) and 22551 (anterior cervical discectomy and fusion), each billed with modifiers 80, 81, 82, or AS. Each CPT code carries a specific Medicare payment policy indicator that determines whether an assistant surgeon is ever payable. Indicator 0 results in automatic denial under CARC 54 regardless of documentation. Indicators 1 or 2 require documentation of medical necessity or exceptional circumstances per CMS Transmittal R1620CP. Billing modifier AS for a physician assistant, nurse practitioner, or clinical nurse specialist assistant without meeting the same underlying policy indicator requirements produces the same denial. Check each CPT code's assistant-at-surgery payment policy indicator before scheduling a case with a planned assistant.

Documentation and Workflow Practices That Win

Orthopedic billing problems are almost always documentation problems before they become billing problems. The following practices address the upstream clinical record issues that create the denial patterns above.

1. Track every patient's global surgical period by procedure and start date. Log the surgery date, the 90-day window end date, and any subsequent procedures or E/M visits scheduled inside that window in the practice management system. Require staff to confirm the window before coding any subsequent visit or procedure.
2. Document a distinct diagnosis for every E/M visit during a global period. Explicitly state why the visit is unrelated to the original surgery, with a separate ICD-10 code that supports modifier 24. Do not rely on the modifier alone.
3. Separate the injection and E/M note when billing modifier 25. For joint injections billed alongside an E/M visit, document a distinct history, exam, and medical decision-making section separate from the injection procedure note before applying modifier 25.
4. Maintain a drug unit-conversion reference table for every injectable. Cross-check kenalog (J3301), hyaluronic acid derivatives (J7325 and related), and any corticosteroid J-code against the current HCPCS descriptor so billed units always match the administered dose.
5. Compile conservative treatment history before every advanced imaging prior authorization. Before submitting an MRI or CT authorization request, include the full physical therapy duration, NSAID trial, and any injections already performed.
6. Verify the assistant-at-surgery payment policy indicator before scheduling. Check the CMS Physician Fee Schedule look-up tool or the AAOS Code-X NCCI checker for every spine or complex joint CPT code before scheduling a case with a co-surgeon or assistant. Document medical necessity or an across-the-board no-resident policy when the indicator requires it.
7. Document the specific clinical reason for every cast or splint replacement. Record structural damage, loss of fit, or skin integrity risk rather than routine or cosmetic reasons. This supports modifier 58 on replacement casting codes.

Frequently Asked Questions

Why do we keep getting denials for E/M visits during a patient's global period after knee replacement?

This is almost always a missing or unsupported modifier 24, which is required when the E/M visit addresses a condition unrelated to the surgery. AAPC compliance audits attribute roughly 30% of orthopedic E/M denials during global periods to a missing modifier 24, so the fix is both a coding step and a documentation step: the note must state a clearly unrelated diagnosis, not just append the modifier. This typically triggers CARC 97.

Can we bill an E/M visit on the same day as a joint injection?

Only if a significant, separately identifiable evaluation was performed beyond the routine assessment inherent to the injection itself, in which case modifier 25 is appended to the E/M code. If the visit was scheduled purely for the injection and no separate exam was documented, billing the E/M service in addition to the injection code is not appropriate and typically triggers a bundling denial under CARC 97.

What is the difference between L-codes and A-codes for orthopedic DME like braces and splints?

L-codes (HCPCS Level II) describe orthotic and prosthetic devices, such as knee braces and spinal orthoses, while A-codes generally describe medical supplies. Billing a brace under the wrong code family, or without a signed physician order and proof of delivery documentation, is a common and avoidable denial. Always confirm the correct code family against the specific device's HCPCS description before submission.

Why was our MRI prior authorization denied even though the patient clearly needs imaging?

Most commercial and Medicare Advantage payers require documentation of a defined period of conservative treatment (physical therapy, NSAIDs, injections) before approving advanced imaging for musculoskeletal complaints, and denials often occur because that history was not explicitly included in the initial authorization request rather than because imaging is not warranted. A 2023 study in the journal Orthopedics found that nearly all peer-to-peer reviews for CT/MRI denials in orthopedic practices resulted in approval, underscoring that most of these are documentation gaps rather than true non-coverage decisions per Muni Health's peer-to-peer analysis.

When should we bill a global fracture care code versus a simple cast application plus an E/M visit?

Bill a global fracture care code only if a restorative treatment (reduction or manipulation of the fracture or dislocation) was performed, or if the treating physician will provide all subsequent fracture care for that patient. If neither condition is met, for example the patient received only a splint and will be referred elsewhere for ongoing care, bill the appropriate E/M code plus the cast or strapping application code instead.

Can we bill a replacement cast during the global period of the original fracture treatment?

Yes, if there is documented medical necessity, such as the cast being damaged, loose, or posing a skin integrity or infection risk. Append modifier 58 to the replacement casting code (for example, 29075, 29125, or 29280) along with a supporting diagnosis. Payers will not reimburse a cast change performed for cosmetic reasons or patient preference alone.

Why does Medicare deny our assistant surgeon claims for spine cases even with strong documentation?

Every CPT code carries a Medicare-assigned assistant-at-surgery payment policy indicator. If that code's indicator is 0, Medicare will deny the assistant surgeon claim outright under CARC 54 regardless of how strong the supporting documentation is. Check the specific code's payment policy indicator before scheduling an assistant, since some spine and complex joint procedures simply do not permit assistant-at-surgery reimbursement under Medicare rules.

Do orthopedic surgeons typically bill for physical therapy, or is that referred out?

Most orthopedic practices refer patients to a separate physical therapy provider, whether hospital-based, independent, or an in-office therapy service billed under a different provider number, rather than billing PT codes under the surgeon's own NPI. When an orthopedic practice does operate an in-house therapy program, it must bill PT evaluation and treatment codes separately from the surgeon's E/M and procedural codes, with its own documentation supporting medical necessity and frequency of visits, distinct from the global surgical package.

How ROI Addresses Orthopedic Denial Patterns

Orthopedic billing problems are systematic. The same global period modifier misuse, the same joint injection bundling errors, and the same assistant surgeon indicator mistakes appear across practices of all sizes. At Revenue Optimization & Intelligence, we built our denial taxonomy around specialty-specific patterns, and orthopedics is one of the most consistently mapped because the code combinations that generate denials are predictable.

• The ROI platform ingests 835 remittance files from any clearinghouse or EHR export and flags CARC/RARC combinations specific to orthopedics, including global period modifier denials, joint injection bundling errors, and assistant surgeon indicator conflicts, automatically routing each to the correct denial category.
• The EDI Code Intelligence Lab includes entries for every CARC and RARC code commonly seen in orthopedics, each with fix, appeal, and prevention guidance written for billing staff who need to act on a denial today rather than read a policy manual.
• Our appeal template library includes orthopedic-specific templates for global period modifier appeals, MRI prior authorization overturns, and assistant surgeon documentation frameworks with clinical language built in.
• Take the free Revenue Health Assessment to see how your orthopedic denial rate compares to specialty benchmarks and where the fastest recovery opportunities sit in your current claim mix.

"Orthopedic billing rewards practices that build global period and modifier discipline into the front end. Every missing modifier 24 is preventable at the scheduler. Every assistant surgeon indicator is knowable before the case is booked. A denial in this specialty is almost always something that could have been caught before the claim ever went out." Mindy Corbett, CSPO, CPC, CPB, CPPM, Founder, Revenue Optimization & Intelligence

Sources

1. Centers for Medicare & Medicaid Services. Calendar Year (CY) 2026 Medicare Physician Fee Schedule Final Rule Fact Sheet (CMS-1832-F). https://www.cms.gov/newsroom/fact-sheets/calendar-year-cy-2026-medicare-physician-fee-schedule-final-rule-cms-1832-f
2. AMGA. Unpacking the 2026 Physician Fee Schedule (Consulting Infographic). https://www.amga.org/getmedia/2d845474-6427-4991-9aab-671e53320657/amga_consulting_infographic_medicare_v4.pdf
3. Centers for Medicare & Medicaid Services. Medicare Claims Processing Manual, Pub. 100-04, Transmittal R1620CP (Assistant-at-Surgery Billing Policy). https://www.cms.gov/Regulations-and-Guidance/Guidance/Transmittals/downloads/R1620CP.pdf
4. MedPrecision Billing. Orthopedic Billing Services (CPT 29881, 27447, 73721 and Global Period Guidance). https://www.medprecisionbilling.com/specialties/orthopedic-billing-services/
5. Muni Health. Peer-to-Peer Review for Insurance Denials: Provider Guide 2026. https://muni.health/blog/peer-to-peer-review-insurance-denials-2026
6. American Academy of Orthopaedic Surgeons. AAOS' Coding Portfolio Provides Resources to Optimize Reimbursement, AAOS Now. https://www.aaos.org/aaosnow/2025/aug-sept/managing/managing02/
7. American Academy of Orthopaedic Surgeons. Coding and Reimbursement Resources. https://www.aaos.org/quality/coding-and-reimbursement/
8. AAPC. Joint Injection With E/M? Append -25 in These Instances. https://www.aapc.com/codes/coding-newsletters/my-orthopedic-coding-alert/joint-injection-with-em-append-25-in-these-instances-article
9. AAPC. ED Fracture Care Redux. https://www.aapc.com/blog/29726-ed-fracture-care-redux/
10. AAPC. Know When You Can Collect for Casting: New NCCI Edits Make Their Debut. https://www.aapc.com/codes/coding-newsletters/my-orthopedic-coding-alert/new-ncci-edits-make-their-debut-know-when-you-can-collect-for-casting-article
11. AAPC. CPT Assistant: Reporting Fracture and Restorative Care and Dislocations. https://www.aapc.com/codes/cpt_assistant/download_pdf_cpt_assistant/3189
12. X12.org. Claim Adjustment Reason Codes (CARC) Master List. https://x12.org/codes/claim-adjustment-reason-codes