CPT code 29871: Knee arthroscopy, infection lavage and drainage2026 Medicare rate & RVUs in Missouri
Reports arthroscopic surgical lavage and drainage of an infected knee joint, typically performed to treat septic arthritis rather than for diagnostic inspection alone.
CMS doesn’t publish an office rate for 29871 in Missouri.
Medicare allowed amount for participating (non-QP) physicians, before deductible, coinsurance and claim adjustments. Not a patient’s bill or a hospital charge.
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What 29871 covers
An orthopedic surgeon uses an arthroscope and instruments to access an infected knee joint, wash out the joint, and drain infectious material. This service is commonly performed in a hospital or ambulatory surgery facility for septic arthritis. The operative record should identify the infection and describe the arthroscopic lavage and drainage performed; a diagnostic look alone does not describe this treatment.
Select this code when arthroscopy is the method used to surgically treat the knee infection, rather than when the primary service is synovectomy or another distinct knee procedure. The 90-day global period includes the day-before preoperative visit and 90 days of related postoperative care. When related endoscopies are performed together, endoscopy family pricing applies. For bilateral surgery, modifier 50 is paid at 150%. CMS does not pay an assistant at surgery; co-surgeons and team surgery are 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.
Where 29871 pays more and less in Missouri
The same RVUs, adjusted for each area’s costs. Open a locality for its calculation, history and nearby areas.
| Payment locality | Office | Facility |
|---|---|---|
| Metropolitan Kansas City, MO | Unavailable | $476.35 |
| Metropolitan St. Louis, MO | Unavailable | $480.45 |
| Rest of Missouri | Unavailable | $458.63 |
How the 29871 rate is calculated
Each of 29871’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 · 29871
RVUs × geographic indexes × conversion factor
Work6.52
6.52 RVUs× 1.000 GPCI
Practice expense6.84
6.84 RVUs× 1.000 GPCI
Malpractice1.35
1.35 RVUs× 1.000 GPCI
Adjusted RVUs
14.7100
Conversion factor
$33.4009
Medicare rate
$491.33
Every GPCI starts at 1.000, the national rate. Enter a ZIP or drag a slider.
Payment rules and modifiers for 29871
29871 has a 90-day global period: related visits in that window are included in the surgery payment.
CMS payment indicators · 29871
Knee arthroscopy, infection lavage and drainage
| 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 | 3 | Endoscopy family rules apply. |
| Bilateral (modifier 50) | 1 | Bilateral with modifier 50 pays 150% of the fee schedule amount. |
| Assistant at surgery (80/81/82/AS) | 1 | Not paid (statutory restriction). |
| Co-surgeons (62) | 0 | Not permitted. |
| 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 · 29871
Knee arthroscopy, infection lavage and drainage
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
29871 without 50 · national facility
$491.33
Knee arthroscopy, infection lavage and drainage
29871-50 · Bilateral: 150%
$737.00
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).
29871 compared with similar codes
Compare codes · National
5 codes, side by side
How to choose
- 29870Knee arthroscopyDiagnostic, with or without biopsy
- 29870 is for diagnostic knee arthroscopy, with or without synovial biopsy. Choose 29871 when the surgeon therapeutically lavages and drains an infected knee.
- 29875Knee synovectomyLimited arthroscopic excision
- 29875 describes limited knee synovectomy. It is not the code for arthroscopic infection lavage and drainage.
- 29876Knee synovectomyTwo or more compartments
- 29876 describes major knee synovectomy. Distinguish extensive synovial removal from lavage and drainage performed to treat infection.
- 27310Knee arthrotomyExploration, drainage, or foreign body
- 27310 represents an open knee-joint approach for drainage or related work. Use 29871 when the infection is treated arthroscopically.
29871 billing questions
When should this be reported instead of diagnostic knee arthroscopy?
Report this code when the surgeon performs arthroscopic lavage and drainage to treat a knee infection. Diagnostic inspection without that therapeutic work is a different service.
Is synovectomy included in this code?
This code identifies arthroscopic treatment of infection by lavage and drainage, not synovectomy based on the extent of synovial removal. Document any distinct procedure performed and evaluate it under its own coding rules.
How is bilateral knee treatment handled?
CMS identifies this as a bilateral procedure; modifier 50 is paid at 150%. Document the work on both knees.
Can an assistant or co-surgeon be reported?
CMS does not pay an assistant at surgery for this code. Co-surgeons and team surgery are not permitted.
What postoperative care is included?
The 90-day global period includes the day-before preoperative visit and 90 days of related postoperative care.
What happens when related endoscopies are performed together?
CMS applies endoscopy family pricing when related endoscopies are performed together. The operative documentation should support each procedure reported.
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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