Total Knee and Hip Replacement CPT Codes: The Orthopaedic Surgeon’s 2026 Arthroplasty Coding Guide

CPT Coding for total knees and total hips is critical for any orthopaedic practice in 2026. Getting the primary codes right is critical, of course, but there are so many things that orthopaedic surgeons have to consider when completing their documentation and coding for these arthroplasty procedures. let's get into it.

The primary CPT codes for total joint arthroplasty are 27447 for total knee replacement (arthroplasty, knee, condyle and plateau) and 27130 for total hip replacement (arthroplasty, acetabular and proximal femoral prosthetic replacement). Both are 90-day global period procedures, which means accurate coding depends as much on what happens in the 90 days after surgery as it does on the operative note itself. Getting the primary code right is usually the easy part; the revenue risk for orthopaedic practices lives in the modifiers, staged or bilateral procedure reporting, and post-operative visits that get bundled into the global period whether or not they were billed correctly.

Why Joint Arthroplasty Coding Deserves Its Own Playbook

Total knee and hip replacement are among the highest-volume, highest-reimbursement procedures in an orthopaedic practice, and they are also among the most audited. A single miscoded modifier or an overlooked staged procedure can mean thousands of dollars in denied or reduced reimbursement per case, multiplied across a surgeon doing dozens of arthroplasties a month. Because these procedures follow a 90-day global period, coding mistakes don’t just affect the surgical claim: they ripple into every post-op visit, complication, and revision billed during that window. For a five-plus surgeon group, that ripple effect is where a meaningful share of annual revenue leakage tends to concentrate.

Core CPT Codes for Total Knee Replacement

27447 (arthroplasty, knee, condyle and plateau, medial AND lateral compartments, with or without patella resurfacing) is the primary code for a standard total knee replacement. Partial or unicompartmental knee replacements are reported separately under 27446, and revision knee arthroplasty has its own family of codes (27486, 27487) depending on whether one or both components are revised. Documentation should clearly support which compartments were replaced and whether the procedure was a primary or revision case, since payers routinely deny claims where the operative note doesn’t explicitly distinguish a revision from a primary replacement.

Core CPT Codes for Total Hip Replacement

27130 (arthroplasty, acetabular and proximal femoral prosthetic replacement) is the primary code for total hip replacement. Partial hip replacement (hemiarthroplasty) is reported under 27125, and hip revision procedures fall under 27134, 27137, or 27138 depending on whether the acetabular component, femoral component, or both are revised. As with knee arthroplasty, the operative note needs to explicitly document which components were addressed, since payers use that language, not the CPT code alone, to validate medical necessity and rule out unbundling.

Modifiers That Make or Break Arthroplasty Claims

Bilateral procedures (modifier 50), staged bilateral replacements performed in separate sessions, and revision cases layered with modifier 22 for significantly increased procedural work are where most arthroplasty coding errors happen. Modifier 22 in particular requires operative documentation that specifically quantifies the added difficulty or time, vague language like ‘more difficult than usual’ is a common reason payers deny the increased reimbursement. Getting modifier 51 (multiple procedures) and 59 (distinct procedural service) right also matters when arthroplasty is combined with hardware removal or other concurrent procedures, since incorrect sequencing or missing modifiers is one of the most common triggers for an NCCI bundling denial.

The Global Period Trap: What Gets Missed After Surgery

Total joint arthroplasty carries a 90-day global period, meaning routine post-operative visits are bundled into the original payment and shouldn’t be billed separately. The revenue leakage risk runs in both directions: practices sometimes bill for visits that should be bundled (triggering denials and compliance risk), and just as often fail to bill for complications or unrelated services that ARE separately billable during the global period, simply because staff assume everything in that window is included. Distinguishing a billable complication from a routine post-op visit requires documentation that ties the additional service to a distinct diagnosis, supported with the correct modifier (24 or 79, depending on the scenario).

Where Documentation Typically Falls Short

The most common documentation gaps in arthroplasty coding are: failing to specify which compartment or component was replaced, missing the explicit primary-versus-revision distinction, thin justification for modifier 22 on complex revisions, and post-op notes that don’t clearly link an unrelated complication to a new diagnosis code. Each of these is a common, specific, and fixable pattern, not a reflection of surgeon skill, but of how much detail a template captures versus what a payer’s claims-adjudication rules require.

Frequently Asked Questions

What is the CPT code for a total knee replacement?

27447 is the primary CPT code for a standard total knee replacement (arthroplasty, knee, condyle and plateau, medial and lateral compartments). Partial knee replacements use 27446, and revisions use 27486 or 27487.

What is the CPT code for a total hip replacement?

27130 is the primary CPT code for total hip replacement (arthroplasty, acetabular and proximal femoral prosthetic replacement). Hemiarthroplasty is reported under 27125, and revisions fall under 27134, 27137, or 27138.

When should modifier 50 be used for joint replacement?

Modifier 50 applies when bilateral joint replacements are performed during the same operative session. Staged bilateral procedures performed on different dates should be billed separately by date of service rather than with modifier 50.

Are post-operative visits after joint replacement billable?

Routine post-operative visits within the 90-day global period are bundled into the original procedure payment and generally aren’t separately billable. Complications or unrelated services during that window may be billable if documentation clearly ties them to a distinct diagnosis and the correct modifier.

Why do arthroplasty claims get denied for modifier 22?

Modifier 22 denials typically happen when documentation doesn’t quantify the added complexity or time involved. Payers expect specific detail, such as unusual anatomy, prior hardware, or extended operative time, rather than general statements that the case was more difficult than usual.

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