CPT code 29874 – Knee arthroscopy loose body removal

Key takeaways

CPT code 29874 covers arthroscopic knee surgery to remove a loose or foreign body, not simple debridement or lavage.

A 90-day global surgery period applies under Medicare, so routine follow-up visits in that window are bundled into the surgical fee.

Most payers require modifier LT or RT. Billing without a laterality modifier is the leading cause of 29874 denials.

The operative note must name the fragment and describe its removal. A note that reads as a wash-out will not support the code.

Claims management software like Pabau flags missing laterality and modifier fields before the claim is submitted.

CPT code 29874: Official descriptor and procedure overview

CPT code 29874 is classified under Endoscopy/Arthroscopy Procedures on the Musculoskeletal System, as maintained by the American Medical Association’s CPT code set. The code sits in the 29800s surgical arthroscopy range alongside codes for meniscectomy, chondroplasty, meniscus repair, and ligament reconstruction.

The procedure involves arthroscopic portal placement, joint inspection, and identification of the loose body. That fragment, whether osteochondral or chondral, is then physically extracted from the joint space. The descriptor’s parenthetical examples are not exhaustive. Any loose or foreign body removed arthroscopically from the knee qualifies, including traumatic cartilage fragments from acute injuries.

What CPT 29874 includes and excludes

Bundled into 29874 is the complete arthroscopic approach: Portal placement, joint insufflation and irrigation, intra-articular inspection, and the removal itself. A common documentation error is describing the irrigation as the primary intervention. Payers require evidence of a distinct physical extraction, not simply a flush that washes debris out.

• Included (bundled, not separately billable): Arthroscopic portal work, saline irrigation, diagnostic inspection performed to locate the loose body, wound closure
• Excluded (may be separately reportable with documentation): Chondroplasty or abrasion arthroplasty (29877), meniscectomy (29880/29881), meniscus repair (29882/29883), synovectomy (29876), ACL reconstruction (29888)
• Not separately billable: Incidental debridement of frayed cartilage performed during the same session without a distinct surgical indication beyond the loose body removal

The critical distinction between 29874 and 29877 is surgical intent. If the operative note documents only smoothing or shaving of cartilage surfaces without removing an identifiable loose fragment, 29877 applies. If an osteochondral piece detached from a lesion is grasped and extracted, 29874 is correct. Both codes may be reportable in the same session when the procedures are genuinely distinct and separately documented. The chart below maps four common note wordings to the code each one supports.

Documentation requirements for the operative note

Missing or vague operative note language is the root cause of most 29874 denials. Payers audit these claims specifically because loose body removal is difficult to distinguish from lavage on a superficially worded note. A superbill alone will not carry the code. The payer reads the operative note behind it.

• Loose body identification: Describe the fragment type (osteochondral, chondral, foreign), estimated size, and location within the joint compartment
• Extraction method: Document that the body was grasped, freed from surrounding tissue if adherent, and removed through a portal rather than flushed out
• Laterality: State explicitly which knee (right or left) was operated on; this supports the LT/RT modifier
• Arthroscopic confirmation: Confirm the procedure was performed under arthroscopic visualization, not open
• Pre-operative imaging: MRI findings showing the loose body should be referenced in the operative note; payers often request imaging to establish medical necessity
• Conservative treatment failure: For commercial payers requiring prior authorization, document that conservative management was attempted before surgery

Building a documentation checklist into the pre-submission workflow catches these omissions before the claim reaches the payer. A 29874 claim denied for lavage-only language needs a full appeal with an addendum from the surgeon. That is far more work than getting the operative note right the first time.

ICD-10 diagnosis codes that support medical necessity

The diagnosis code must support the clinical rationale for removing a loose body from the knee. Using a code that describes only arthritic changes without specifying a loose fragment is a common medical-necessity denial trigger.

Codes describing only degenerative joint disease (M17.x) without a specific loose body or OCD diagnosis typically fail medical necessity review for 29874. The diagnosis must logically support the removal of an identifiable fragment, not general arthritis. Before settling on M23.4x or M93.26x, read each code’s full descriptor and its Excludes notes in the ICD-10-CM codes library.

CPT 29874 vs. 29877 vs. 29881 vs. 29880: Choosing the right code

The knee arthroscopy surgical family is one of the highest-volume sources of coding errors in orthopedic billing. These codes share the same approach but differ by what the surgeon does inside the joint.

Embedding these code-family rules in the billing workflow beats asking coders to recall them claim by claim, especially across a high-volume orthopedic caseload.

NCCI edits and bundling rules for knee arthroscopy pairs

The National Correct Coding Initiative (NCCI) governs which knee arthroscopy codes can be reported together. Reporting 29874 alongside 29881 is a common scenario when a loose body removal and a meniscectomy are performed during the same session. NCCI edit status for code pairings changes quarterly. Always verify against the current CMS NCCI tables before submitting combination claims.

Modifier 59 signals a distinct procedural service, but it does not by itself override an NCCI edit if the documentation does not support separation. Payers increasingly audit modifier-59 usage on surgical code pairs. The operative note must describe the loose body procedure and the meniscectomy as separate surgical steps. Each has to address a different anatomical problem, rather than forming one continuous debridement.

Which modifiers to apply

Modifier selection for CPT code 29874 follows the same logic as other knee arthroscopy codes, with laterality modifiers as the non-negotiable starting point.

Medicare reimbursement for CPT code 29874 (2025 and 2026)

Medicare reimbursement for CPT code 29874 is set annually through the Medicare Physician Fee Schedule (MPFS). The amount a practice receives varies by Geographic Practice Cost Index (GPCI) locality, so national averages are a starting point rather than a guarantee. Use the CMS MPFS lookup tool with your MAC locality to get the rate that applies to your practice address.

Because MPFS figures change with each annual update and vary by locality, publishing a specific dollar amount here would go stale within months. Run the code through the CMS tool with your own GPCI locality instead. Commercial payers set their own fee schedules, usually as a multiplier of the Medicare rate, and negotiated rates vary widely by contract.

The 90-day global period bundles post-operative knee care into the 29874 payment. Any evaluation and management service inside that window counts as part of the surgical fee. Separate billing for routine follow-up inside that window will be denied. Unrelated E&M services can still be billed with modifier 24, which tells the payer the visit is not connected to the surgery. Tracking the global period start date against every subsequent visit is what stops those claims going out.

Prior authorization requirements by payer type

Medicare does not require prior authorization for CPT 29874 under standard Part B fee-for-service. Medicare Advantage plans follow their own authorization policies, and many of them require it. Commercial payers vary widely, and most require prior authorization for any arthroscopic surgical procedure.

• Medicare FFS: No prior auth required in most cases; Local Coverage Determinations (LCDs) from your MAC govern medical necessity criteria
• Medicare Advantage: Auth requirements vary by plan; check plan-specific policy before scheduling
• Commercial payers: Most require prior auth; submit with imaging (MRI confirming loose body) and documentation of conservative treatment failure
• Typical timeline: 3-10 business days for standard review; urgent requests may be processed within 24-72 hours
• Consequences of missing auth: Claim denial as “not authorized”. Most payers allow an appeal, though patient responsibility may shift depending on plan terms and whether an ABN was obtained

Checking the auth requirement at scheduling prevents claim delays instead of fixing them after a denial. Tracking authorization status against the procedure date matters most for 29874, given how much commercial payer volume an orthopedic practice carries.

Practices using claims management software can link authorization numbers directly to the claim before submission. That removes the manual step of cross-referencing an auth log at billing time.

Common denial reasons and how to prevent them

CPT code 29874 denials cluster around a small number of predictable causes. Most are preventable at the pre-submission stage with the right documentation and modifier review. A denial review step built into the billing cycle catches them before they reach the payer.

An appeal on a denied 29874 claim usually needs a cover letter quoting the operative note language that separates extraction from lavage. Attach the MRI report and any diagnostic arthroscopy images. Where the denial is an NCCI bundling edit, include a copy of the current table showing the modifier indicator. Add the note sections for each billed procedure.

Place of service and facility billing considerations

CPT 29874 is almost exclusively performed in a hospital outpatient department (POS 22) or ambulatory surgery center (POS 24). The place of service decides which fee schedule applies to the physician’s claim. For Medicare, it also decides whether the facility or non-facility PE RVU is used.

• Hospital outpatient (POS 22): Physician bills under the facility rate, which carries the lower PE RVU. The hospital bills Medicare separately for the facility fee under the Outpatient Prospective Payment System (OPPS)
• ASC (POS 24): Physician bills under the facility rate; the ASC separately bills under the ASC fee schedule; physician reimbursement matches POS 22
• Office (POS 11): Not applicable for 29874. Arthroscopic knee surgery is not performed in an office setting, so POS 11 will trigger a denial

Setting the POS code correctly at charge entry is what prevents this category of denial. A claim submitted with POS 11 for an ASC procedure will be rejected. Correcting it takes a full void and resubmission rather than an amendment.

On an electronic claim, the 837 file carries the POS code in the service line segment. Validating that field before submission heads off the same problem. The remittance advice on a denied facility-setting claim usually shows CARC 4 or CARC 96, depending on how the payer reads the mismatch.

How Pabau keeps 29874 claims clean before submission

In most orthopedic practices the checks on this code happen by hand. A coder opens the operative note and confirms the fragment was described as removed. Then they look up the authorization number in a separate log and append LT or RT. Each of those steps is a place where a clean claim quietly turns into a denial.

Practice management software like Pabau keeps the operative note, the authorization number, and the claim line in one patient record. Laterality and modifier fields are validated as the charge is entered, so a 29874 line cannot leave the practice without them. Claims then route to the payer through our Claim.MD clearinghouse integration, which scrubs the file before it goes out.

The global period runs against the procedure date in the same system. A post-operative visit booked inside the 90-day window is flagged before anyone bills it. Billers spend their time on the appeals that are worth fighting, rather than on rework the practice could have avoided.

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Pabau’s claims management software tracks modifier requirements, authorization status, and global periods, so your 29874 claims submit clean the first time. See how it works for your practice.

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Conclusion

This code stands or falls on one sentence in the operative note. Where the surgeon names the fragment and describes taking it out, 29874 survives an audit. Where the note reads as a wash-out, no modifier and no appeal letter will rescue the claim.

That puts the work before the claim exists rather than after it. Agree the wording with your surgeons, make laterality a required field at charge entry, and check the NCCI indicator before anyone appends modifier 59. Those three habits remove most of the denials described on this page, and they cost far less than the appeals they replace.

Book a demo to see how Pabau validates laterality, modifiers, and global periods on surgical claims before they reach the payer.

Continue your research

Need to understand how clearinghouse submission works? Medical claims clearinghouse guide explains how claims are scrubbed and routed before they reach the payer.

Want to reduce claim rejections before submission? Revenue cycle management overview covers the end-to-end billing workflow from charge capture to payment posting.

Billing multiple procedures in the same session? CPT coding reference for multi-procedure billing walks through how to document and report multiple codes on a single claim.

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