Open surgical repair of an acromioclavicular (AC) joint dislocation, whether acute or chronic, using internal fixation hardware such as pins or screws.

Verified May 8, 2026 · 6 sources ↓

Medicare: $540.76
Total RVUs: 16.19
Global, days: 90
Region: Shoulder

Drawn from CMSAAPCFindacodeAbos

Documentation requirements

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

Source · Editorial brief grounded in 6 cited references ↓

Specify acute vs. chronic presentation — timing and mechanism of injury or onset of instability
Document AC joint grade (Rockwood classification or equivalent) to support medical necessity
Name the fixation method and hardware used (e.g., hook plate, CC screw, TightRope, pins)
Confirm coracoclavicular ligament status in the operative note — repair is bundled; graft reconstruction is not
Record laterality explicitly — left, right, or bilateral — in both the operative note and the claim
If billing modifier 22, document specific intraoperative factors that increased time or complexity beyond typical

Applicable modifiers

Modifiers commonly billed with this code.

Source · AMA CPT modifier descriptors · CMS NCCI Policy Manual

22 Increased complexity 24 Unrelated E/M during global 25 Significant separate E/M 50 Bilateral procedure 51 Multiple procedures 52 Reduced services 57 Decision for surgery 58 Staged or related 59 Distinct service 62 Co-surgeons 73 Discontinued pre-anesthesia 74 Discontinued post-anesthesia 76 Repeat, same physician 77 Repeat, another physician 78 Unplanned return — related 79 Unrelated during global 80 Assistant surgeon LT Left side RT Right side

What this code covers

Source · Editorial summary grounded in 6 cited references ↓

CPT 23550 covers open treatment of an AC joint dislocation — the separation between the clavicle and the acromion — in both acute trauma presentations and chronic instability cases. The procedure involves surgical exposure of the AC joint, reduction of the dislocated segment, and fixation with internal implants. Coracoclavicular ligament repair, when performed as part of the same procedure, is bundled into 23550 and cannot be billed separately. If the surgeon also performs fascial graft reconstruction, step up to 23552 instead.

The 90-day global period applies. All routine follow-up, dressing changes, and post-op visits through day 90 are included in the surgical payment. Billing an E&M during that window requires modifier 24 (unrelated problem) or modifier 25 (same-day significant separately identifiable E&M pre-op). Laterality matters: attach LT or RT on every claim — bilateral AC dislocations are rare but modifier 50 applies if both sides are treated in the same session.

RVU & reimbursement

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

Source · CMS Physician Fee Schedule, RVU26A · January 2026

Work RVU	7.4
Practice expense RVU	7.33
Malpractice RVU	1.46
Total RVU	16.19
Medicare national rate	$540.76
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	$540.76
HOPD (APC 5114) Hospital outpatient department	$7,413.38
ASC (PI J8) Ambulatory surgical center (freestanding)	$4,903.83

Common denial reasons

The recurring reasons claims for CPT 23550 get rejected.

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

Missing or ambiguous laterality — claim lacks LT or RT modifier, triggering payer edit
Separate billing for coracoclavicular ligament repair, which is inclusive in 23550 and not separately payable
Upcoding to 23552 without documentation of fascial graft harvest and use
E&M billed in the 90-day global without modifier 24 or 25 to justify separate payment
ICD-10 diagnosis code doesn't specify AC joint dislocation (S43.1xx series), causing CPT-diagnosis mismatch

Frequently asked questions

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

01Is coracoclavicular ligament repair separately billable when performed with 23550?

No. CC ligament repair is considered inclusive in 23550 and cannot be billed separately. If the surgeon performs fascial graft reconstruction of the CC ligament, bill 23552 instead — that code specifically includes graft harvest.

02When does 23550 step up to 23552?

Use 23552 when the stabilization requires a fascial graft, including procurement. The graft harvest and use must be documented in the operative note. Simple internal fixation with ligament repair stays at 23550.

03What ICD-10 codes pair with 23550?

The S43.1xx series covers AC joint dislocation — S43.101 through S43.119 depending on laterality and severity. Chronic instability may also map to M24.219 (chronic dislocation of shoulder joint). Confirm the encounter-specific code reflects the documented grade and acuity.

04Can 23550 be billed bilaterally?

Bilateral AC dislocations are uncommon but do occur in high-energy trauma. If both sides are treated in the same operative session, append modifier 50. Some payers instead want two line items with LT and RT — verify payer-specific billing rules before submitting.

05What modifier applies if the surgeon has to return to the OR for a related complication during the 90-day global?

Use modifier 78 for an unplanned return to the operating room for a complication related to the original AC joint procedure within the global period. Modifier 79 applies only if the return procedure is unrelated to the original surgery.

06Can an E&M be billed on the same day as 23550?

Yes, if the E&M represents a significant, separately identifiable service — for example, a separate decision-making encounter prior to scheduling the surgery. Append modifier 25 to the E&M. A routine pre-op assessment on the same day is not separately billable.

07Is there a difference in reimbursement between the HOPD and ASC settings for 23550?

Yes — site of service significantly affects payment. See the Site of Service comparison table on this page for the HOPD and ASC amounts under the CMS Physician Fee Schedule 2026.

Sources & references

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

Mira AI Scribe

Mira's AI scribe captures AC joint dislocation grade, acuity (acute vs. chronic), surgical approach, fixation hardware by name, coracoclavicular ligament status, and operative laterality directly from dictation. That documentation prevents the two most common denial triggers: missing laterality on the claim and improper unbundling of CC ligament repair.

See how Mira captures CPT 23550 documentation