CPT Code 73564: Radiologic examination, knee, 4 or more views

Key takeaways

CPT Code 73564 describes a complete radiologic examination of the knee requiring 4 or more views, as defined by the American Medical Association.

The view count must be explicitly documented in the radiology report. Billing 73564 without a recorded count is a common audit trigger.

Modifier 50 or RT/LT applies when both knees are imaged. Some payers want CPT 73565 instead for bilateral standing views, so confirm the rule with each one.

Practice management software like Pabau validates CPT and ICD-10 pairings through the Claim.MD clearinghouse before a claim ever reaches the payer.

CPT Code 73564 is the billable code for a complete radiologic examination of the knee with four or more views.

It sits at the top of the knee X-ray family, above 73560 for one or two views and 73562 for three. Which of them you may bill comes down to the view count written in the radiology report, not the protocol named on the order.

This guide covers the full descriptor, the clinical indications, and how 73564 compares with the rest of the knee radiology family. It then works through modifiers, ICD-10 pairings, Medicare rates, and the documentation that keeps these claims clean.

What CPT Code 73564 covers

The official descriptor, as published by the American Medical Association, is: Radiologic examination, knee; complete, 4 or more views. It sits within the CPT Radiology section, under Diagnostic Radiology (Diagnostic Imaging), Lower Extremity.

“Complete” is the operative word, and four views is the minimum threshold. A standard complete series commonly runs anteroposterior (AP), lateral, oblique, and weight-bearing AP projections. Protocols that stretch past four often add an intercondylar (tunnel) view. If the report documents fewer than four, 73564 is the wrong code.

When to use a complete knee series

Bill 73564 when a complete knee series is medically necessary and the imaging protocol captures four or more projections. These are the scenarios that most often reach that threshold.

• Osteoarthritis evaluation. A four-view series with a standing weight-bearing AP is standard for staging joint space narrowing, osteophytes, and subchondral change. Arthritis workups routinely reach four views and support ICD-10 codes in the M17.x range.
• Trauma assessment. Acute knee trauma protocols add oblique views to catch fractures, avulsions, or tibial plateau involvement that a two-view study misses. Four or more views taken for trauma support 73564 over the lower-view codes.
• Pre-surgical planning. Orthopedic surgeons ordering a complete preoperative baseline usually request AP, lateral, oblique, and weight-bearing projections. That puts the study inside the 73564 threshold.
• Post-surgical follow-up. Monitoring implant position or joint restoration after arthroplasty or ligament repair takes a full multi-view series, which supports 73564.
• Weight-bearing protocol studies. Standing views show dynamic joint space changes that non-weight-bearing positions hide. When the ordering clinician specifies weight-bearing and the tech captures four or more views in total, 73564 is the correct code.

Clinical indication alone does not finish the job. The radiology report still has to record how many views were obtained. Without that count, even a medically appropriate study creates audit exposure once it is billed as 73564.

CPT Code 73564 vs related knee X-ray codes

The knee radiology family runs from 73560 to 73565, and the documented view count picks the code. Billing CPT 73562 when four views were obtained and written up leaves money on the table. Billing 73564 on three documented views creates overpayment exposure instead.

Bilateral imaging complicates that ladder, because two codes in the family handle both knees in different ways. The table below adds the bilateral option alongside each view count.

Bilateral knee imaging: 73564 or 73565?

CPT 73565 describes one very specific study: a bilateral standing anteroposterior view and nothing more. It is not a complete bilateral knee series. When both knees get a full multi-view protocol of four or more views each, 73564 is the base code. The bilateral component then varies by payer.

• Modifier 50 (bilateral procedure). Appended to a single line of 73564 to show the procedure was performed on both sides. Many Medicare carriers accept this for a bilateral complete knee series.
• RT/LT modifiers. Some payers prefer two separate line items, one carrying RT for the right knee and one carrying LT for the left.
• 73565 instead. When the only bilateral imaging obtained is a standing AP view for joint space comparison, 73565 is more precise than 73564 with a bilateral modifier. Check the payer’s local coverage determination (LCD) first.

Modifiers that apply to a complete knee series

Modifier selection depends on the place of service, whether both knees were imaged, and how the professional and technical components are billed. The CMS National Correct Coding Initiative (NCCI) governs bundling rules for radiology codes. Review the applicable NCCI edits before you append more than one modifier to the same claim line.

In an office where the physician owns the equipment and performs the interpretation, no modifier is needed and the global fee applies. Separating the components without a valid split-billing arrangement creates a compliance risk.

ICD-10 codes that support medical necessity

Medical necessity for a complete knee series rests on the diagnosis code behind the imaging order. Not every ICD-10 code satisfies payer criteria for four or more views. The clinical documentation has to connect the diagnosis to the need for a comprehensive study. Pull the code from the ICD-10-CM code library rather than a memorized shortlist, because laterality and specificity both decide whether the claim pays.

The codes below are the ones that pair with a four-view knee study most often. For crosswalk lookups by payer policy, the AAPC CPT-to-ICD-10 crosswalk maps these relationships in more detail.

Laterality specificity matters here. Payers audit for a mismatch between the side named in the diagnosis code and the side named in the modifier. A claim for M17.11, right knee osteoarthritis, billed with modifier LT will be denied whatever the clinical record says.

Medicare reimbursement rates for 2026

Medicare payment for a complete knee series varies by geographic payment locality and by whether the service is furnished in a facility or non-facility setting. Use the CMS Physician Fee Schedule Look-Up Tool to retrieve the exact rate for your payment area and the current program year.

Those figures are approximate national averages, shown for illustration only. Geographic adjustment factors and annual conversion factor updates both move the payment. Verify against the CMS fee schedule tool before you put any of them into a revenue projection.

Medicare vs commercial payer rates

Commercial payers usually reimburse above Medicare, often between 110% and 150% of the Physician Fee Schedule. The spread varies a lot by contract and region. Self-pay and workers’ compensation rates are negotiated separately and can sit well outside both.

A practice that sets charge master amounts from Medicare benchmarks alone risks leaving commercial revenue behind. It can also price charges below the rate it has already contracted for.

What the radiology report must document

The most audited element in a 73564 claim is the view count, ahead of both the diagnosis code and the modifier. The report has to state how many views were obtained, not simply name the projections. Listing “AP, lateral, oblique” without a total leaves the coder guessing. Here is the full checklist.

• View count stated outright. The report should say “4 views obtained” or name four or more projections. An implicit assumption drawn from a standard protocol will not hold up in an audit.
• Laterality documented. Right knee, left knee, or bilateral has to appear in both the report and the order. Ambiguous laterality creates claim edit exposure.
• Clinical indication. The ordering provider’s reason for the study belongs on the order or referral. A study ordered for knee pain must link to the appropriate M25.56x code, not a more specific condition the record does not support.
• Weight-bearing notation, where it applies. Note standing or weight-bearing views in the protocol section. Weight-bearing often differentiates arthritis severity staging and supports the case for the more comprehensive series.
• Radiologist signature and date. The interpreting physician has to sign the final report before billing. Billing from a preliminary read is an audit risk.

Build a pre-submission check that compares view count, laterality, and indication across the order, the report, and the claim. Run it before the 837P file is generated. That one step removes a large share of avoidable 73564 denials.

Common billing mistakes with CPT Code 73564

Most 73564 denials trace back to a short list of recurring errors. Working out which one your practice repeats is more useful than a general compliance audit. These are the highest-frequency issues in knee radiology billing.

• Undercoding to 73562 when four views were obtained. Coders working from a standard three-view order sometimes default to 73562 even after the technologist captured an extra oblique or patella view. The report, not the order, sets the code. Review the tech’s view log against the report first.
• Missing view count in the radiology report. This is the most common audit trigger. If the report describes projections without a total, the coder should query the radiologist before billing. Submitting without that confirmation creates overpayment exposure.
• Incorrect bilateral modifier usage. Billing 73564 with modifier 50 where the payer expects two RT/LT line items generates an automatic edit. Confirm each payer’s preference first, especially for Medicare Advantage plans that follow commercial rules.
• Missing laterality modifier entirely. Some payers accept a unilateral 73564 with no laterality modifier. Omitting RT or LT on a bilateral claim, or where the diagnosis code names a side, creates a mismatch that auditors flag.
• Billing 73564 and 73562 for the same knee in one encounter. The two codes are mutually exclusive for a single knee at a single encounter. NCCI edits bundle them, and unbundling without a valid modifier is a compliance violation.

A clean 73564 claim has view count, laterality, diagnosis, and modifier all in agreement before the 837 file leaves the practice. Flagging the mismatches at charge entry heads off the submit, deny, correct, resubmit cycle that erodes net collections.

How to streamline knee X-ray billing in your practice

Orthopedic and radiology practices with high knee imaging volumes gain the most from a systematic approach. Manual code selection off a worklist breeds inconsistency. One tech captures five views and the next captures three, with no standard report template behind either. Coders then reconstruct view counts from narrative text.

• Build structured report templates. Work with your radiologists on a template that carries a mandatory “total views obtained” field. Populate it from the PACS or require it before sign-off, and the count is never missing at billing time.
• Set up order set defaults. Create a complete knee series order set in your EMR that defaults to 73564 and prompts for laterality and indication. That drives consistent coding from the point of order entry.
• Validate claims at the clearinghouse. A clearinghouse integration can check CPT and ICD-10 pairings before submission, catching laterality mismatches and missing modifiers before the payer sees the claim.
• Automate prior authorization checks. Some commercial payers require prior authorization for knee X-rays, particularly on repeat studies. Build the lookup into scheduling so the authorization is secured before the patient arrives.
• Track denial patterns by code. Filter denials for 73564 alone in claims software for radiology, then group them by payer. If one payer generates most of the rejections, the fix is a payer-specific rule rather than a documentation problem.

How Pabau validates 73564 claims before they go out

In most radiology and orthopedic practices, the check on a 73564 claim happens after the payer rejects it. A biller reads the remittance, works out that the laterality modifier disagreed with the diagnosis code, corrects the line, and resubmits. That round trip adds weeks of aging to a claim the fee schedule values at roughly $45 to $60.

Practice management software like Pabau moves that check to the front of the process. The built-in CPT and ICD-10 catalogs flag an invalid pairing at charge entry. The Claim.MD clearinghouse integration then validates the claim again before it reaches the payer. Submission runs on CMS-1500 and 837P files, with real-time eligibility checks alongside it.

Electronic remittance advice comes back as an 835 file and posts automatically, so the denial data you need for a payer-level view builds itself. Your biller sees a missing RT modifier while the encounter is still open, instead of six weeks later on a denial report. Every Pabau subscription includes claims management, so the whole workflow is available from the first day.

Catch knee X-ray coding errors before the payer does

Pabau validates CPT and diagnosis pairings through the Claim.MD clearinghouse before a claim is submitted. View-count mismatches and missing laterality modifiers get flagged at charge entry, not on a denial report.

Book a demo

Conclusion

CPT Code 73564 is simple to define and stubbornly easy to get wrong. Four views have to be documented, not assumed and not inferred from a standard protocol. Three variables decide whether a claim pays on first submission. They are the view count in the report, laterality alignment, and the right modifier for the setting.

Start with the report template. A mandatory total-views field costs one conversation with your radiologists and closes the most common denial reason on this code for good. The modifier rules are payer-specific and will keep shifting, so keep a short crib sheet by payer rather than trying to standardize them.

Book a demo to see how Pabau flags a view-count or laterality mismatch on a knee X-ray claim before it is ever submitted.

Continue your research

Need to understand how claims move from practice to payer? Medical claims clearinghouse guide explains the end-to-end submission process, edits, and ERA handling.

Getting denials without a clear reason code? Denial management in healthcare covers how to categorize, appeal, and systematically reduce claim rejections.

Want to verify eligibility before the patient arrives? Insurance eligibility verification walks through real-time eligibility checks and how to connect them to your scheduling workflow.

Frequently asked questions