Billing code 27310: Knee arthrotomyMedicare rate & RVUs in Guam
Reports open knee-joint access to investigate a joint problem, drain infection, or remove an intra-articular foreign body during surgery.
CMS doesn’t publish an office rate for 27310 in Guam.
Medicare allowed amount for participating (non-QP) physicians, before deductible, coinsurance and claim adjustments. Not a patient’s bill or a hospital charge.
On this page 9 sections
What 27310 covers
An orthopedic surgeon opens the knee joint to inspect its interior, drain infected material, or remove a foreign object. A typical setting is the operating room, including surgery for a suspected or confirmed septic knee joint. The procedure is open: it is not the arthroscopic approach used to inspect or treat the joint through small portals.
Report 27310 when the operative work is open exploration, drainage, or foreign-body removal, and document the approach, indication, intra-articular findings, and work performed. The code has a 90-day global period, which includes the day-before preoperative visit and 90 days of related postoperative care. When multiple procedures occur in the same session, the highest-valued procedure is paid in full and other procedures are subject to the standard 50% reduction. Bilateral reporting with modifier 50 is paid at 150%. An assistant at surgery may be paid; co-surgeon payment requires supporting documentation, and team surgery is not permitted.
This summary was written with AI assistance from CMS physician fee schedule data and checked against the CMS billing rules shown here. Rates on this page come directly from CMS files.
27310 in Hawaii, Guam
| Payment locality | Office | Facility |
|---|---|---|
| Hawaii, Guam | Unavailable | $700.64 |
How the 27310 rate is calculated
Each of 27310’s three RVUs is multiplied by a geographic index (GPCI) for the payment locality, added up, and multiplied by the conversion factor. Drag the indexes or enter a ZIP to see what moves the rate.
How the rate is built · 27310
RVUs × geographic indexes × conversion factor
Swap in your local Medicare rate.
Work 9.75Practice expense 8.83Malpractice 2.05
All indexes start at 1.000 (the national rate). Enter a ZIP or drag a slider.
Payment rules and modifiers for 27310
27310 has a 90-day global period: related visits in that window are included in the surgery payment.
CMS payment indicators · 27310
Knee arthrotomy
| Rule | CMS value | What it means |
|---|---|---|
| Global period | 090 | Major surgery: the day before, the day of, and 90 days after are included. |
| Multiple procedures | 2 | Standard reduction: highest-valued procedure at 100%, others at 50%. |
| Bilateral (modifier 50) | 1 | Bilateral with modifier 50 pays 150% of the fee schedule amount. |
| Assistant at surgery (80/81/82/AS) | 2 | Paid. |
| Co-surgeons (62) | 1 | Permitted with supporting documentation. |
| Team surgery (66) | 0 | Not permitted. |
| Professional/technical | 0 | Physician service: no professional/technical split. |
| Split (54/55/56) | 0.10/0.69/0.21 | Share of the payment for pre-op, the procedure itself, and post-op care. |
Global surgery period · 27310
Knee arthrotomy
90-day global period ends
Dec 30, 2026
Covers Sep 30, 2026 through Dec 30, 2026 (92 days, including the day before surgery).
Visit on Oct 31, 2026
Day 30 of the 90-day post-op period: related follow-up care is included in the surgical payment.
Pre-op dayGlobal period
What modifiers do to the payment
Modifier 50 · payment effect
With and without the modifier
27310 without 50 · national facility
$689.06
Knee arthrotomy
27310-50 · Bilateral: 150%
$1,033.59
Both sides on one line with modifier 50 are paid at 150% of the fee schedule amount (subject to multiple-procedure rules with other procedures).
27310 compared with similar codes
Compare codes
27310 vs 27330 vs 27331 vs 29871: national Medicare rates
Swap in your local Medicare rate.
How to choose
- 27330Knee biopsy
- Choose 27330 when the open knee-joint procedure is for biopsy. Choose 27310 for exploration, drainage, or foreign-body removal.
- 27331Knee arthrotomy
- 27331 represents a different open knee-joint service centered on synovectomy; 27310 is for exploration, drainage, or foreign-body removal.
- 29871Knee arthroscopy
- 29871 is the arthroscopic approach to knee treatment. 27310 describes open joint access for exploration, drainage, or foreign-body removal.
27310 billing questions
When is 27310 a better fit than knee arthroscopy?
Use 27310 for the described open joint approach. Arthroscopic drainage or treatment uses an arthroscopy code when that method is performed.
How does 27310 differ from an open knee-joint biopsy?
27310 represents exploration, drainage, or foreign-body removal. When the operative purpose is obtaining a synovial or other joint biopsy, consider 27330 instead.
Does the 90-day global include routine postoperative care?
Yes. The global period includes the day-before preoperative visit and 90 days of related postoperative care.
Can an assistant or co-surgeon be reported?
An assistant at surgery may be paid. Co-surgeon payment requires supporting documentation; team surgery is not permitted.
How is bilateral reporting handled?
For bilateral knee procedures, modifier 50 is paid at 150% under the CMS bilateral rule for this code.
What happens when another procedure is performed in the same session?
The highest-valued procedure is paid in full, and other procedures are subject to the standard multiple-procedure reduction.
Where these rates come from
FeeBase calculates base physician payments from CMS work, practice-expense and malpractice RVUs, adjusted by each locality’s geographic indexes and the conversion factor. Services without a published rate are labeled, never given a made-up amount. Amounts are Medicare allowed amounts before claim adjustments: not a patient’s bill or a commercial rate.
CMS RVU26D · effective Oct 1, 2026 through the day before Jan 1, 2027
Show the CMS file lines behind this rate
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