Open reconstruction of both the intra-articular and extra-articular ligaments of the knee, with or without graft augmentation.

Verified May 8, 2026 · 6 sources ↓

Medicare: $1,172.04
Total RVUs: 35.09
Global, days: 90
Region: Knee

Drawn from CMSAAPCEmednyFindacode

Documentation requirements

What must appear in the operative or office note to support the claim.

Source · Editorial brief grounded in 6 cited references ↓

Specify that both intra-articular AND extra-articular ligament reconstruction were performed — documentation of only one component supports 27427 or 27428, not 27429
Name each ligament reconstructed (e.g., ACL, MCL, POL, LCL) and whether the approach was open vs. arthroscopic
Document graft type and source (autograft with harvest site, allograft, or synthetic) including preparation technique
Record laterality explicitly (left, right, or bilateral) in the operative note and on the claim
Describe fixation method and hardware used, including implant manufacturer and lot number per facility implant log requirements
Note any concurrent procedures performed and confirm they are not bundled under NCCI edits 27427–27429

Applicable modifiers

Modifiers commonly billed with this code.

Source · AMA CPT modifier descriptors · CMS NCCI Policy Manual

22 Increased complexity 50 Bilateral procedure 59 Distinct service 76 Repeat, same physician 78 Unplanned return — related 79 Unrelated during global LT Left side RT Right side

What this code covers

Source · Editorial summary grounded in 6 cited references ↓

CPT 27429 covers open knee ligament reconstruction that addresses both intra-articular structures (inside the joint capsule) and extra-articular structures (outside the capsule) in the same operative session. This distinguishes it from 27427, which is limited to extra-articular reconstruction only, and 27428, which covers intra-articular reconstruction alone. Graft use — autograft, allograft, or synthetic augmentation — does not change the code selection; document graft type and source in the operative note regardless.

A critical NCCI bundling rule applies: arthroscopic ACL reconstruction codes 29888 and 29889 are bundled into 27427–27429 and cannot be reported separately with 27429. If the reconstruction was performed open (as required for 27429), billing a concurrent arthroscopy code for the same ligament work will trigger a denial. The 90-day global period covers all routine post-op care, meaning follow-up visits, wound checks, and stitch removals through day 90 are included. Unrelated problems treated in that window require modifier 24 on the E/M.

RVU & reimbursement

Component RVUs and Medicare national rate. Actual payment varies by GPCI locality.

Source · CMS Physician Fee Schedule, RVU26A · January 2026

Work RVU	17.1
Practice expense RVU	14.35
Malpractice RVU	3.64
Total RVU	35.09
Medicare national rate	$1,172.04
Global period	90 days

Payment by site of service

Medicare pays different rates by setting. HOPD typically pays substantially more than ASC for the same procedure.

Source · CMS OPPS Addendum B·ASC HCPCS payment rates·2026

Setting	Medicare rate (national)
Office (PFS non-facility) Procedure performed in physician's office	$1,172.04
HOPD (APC 5115) Hospital outpatient department	$13,116.76
ASC (PI J8) Ambulatory surgical center (freestanding)	$9,649.87

Common denial reasons

The recurring reasons claims for CPT 27429 get rejected.

Source · Editorial brief grounded in CMS NCCI edits, AAOS coding appeals, and cited references ↓

Billing 29888 or 29889 alongside 27429 — these arthroscopic ACL codes are NCCI-bundled into 27427–27429 and will be denied
Operative note documents only intra-articular or only extra-articular reconstruction, supporting 27428 or 27427 respectively rather than 27429
Missing or ambiguous laterality — claim submitted without LT/RT modifier when payer requires it, triggering an edit
Routine post-op E/M visits billed without modifier 24 during the 90-day global period
ICD-10 diagnosis code does not support the complexity of combined intra- and extra-articular reconstruction (e.g., isolated ACL sprain coded when multi-ligament instability is the clinical picture)

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 6 cited references ↓

01What is the difference between 27427, 27428, and 27429?

27427 = extra-articular reconstruction only. 27428 = intra-articular reconstruction only. 27429 = both intra-articular and extra-articular in the same session. You need documented work on both compartments to support 27429.

02Can I bill 29888 (arthroscopic ACL reconstruction) with 27429?

No. Per NCCI policy, CPT codes 29888 and 29889 are bundled into 27427–27429. Billing them together will result in denial of the arthroscopy code. If the procedure is open and meets 27429 criteria, that is the correct and only code for the ligament work.

03If I reconstruct the ACL open and also perform an MCL and POL repair in the same session, does that support 27429?

Potentially yes — ACL reconstruction addresses an intra-articular ligament, while MCL and POL are extra-articular. If all work is open and fully documented, the combination supports 27429. Document each ligament by name and confirm the approach is open, not arthroscopic.

04How does the 90-day global period affect post-op billing for 27429?

All routine follow-up visits, wound care, and stitch removals within 90 days are included in the global and cannot be billed separately. Use modifier 24 on any E/M for an unrelated condition treated during that window, and modifier 78 if the patient returns to the OR for a related complication.

05Is modifier 22 appropriate for a particularly complex multi-ligament reconstruction billed under 27429?

Yes, if the work substantially exceeded the typical intra- and extra-articular reconstruction — for example, significant scar tissue excision, complex graft preparation, or additional stabilization procedures. Attach a narrative letter explaining the added work and time. Payer approval is not guaranteed; document thoroughly.

06Can 27429 be billed bilaterally?

Bilateral same-session reconstruction is rare but possible. Append modifier 50 and confirm the operative note documents separate reconstruction of both the intra-articular and extra-articular ligaments on each knee. Most payers will require prior authorization for bilateral knee reconstruction.

Sources & references

Editorial content was developed using the following public sources. Last verified May 8, 2026.

Mira AI Scribe

Mira's AI scribe captures the operative narrative and flags whether both intra-articular and extra-articular ligament work is documented by name — the exact distinction that separates 27429 from 27427 and 27428. It also notes graft type, laterality, and approach, preventing the most common audit trigger: an operative note that describes only one component of a dual-structure reconstruction.

See how Mira captures CPT 27429 documentation