The One FY 2027 Deletion With Nothing to Replace It
Thirty ICD-10-CM codes stopped being billable on October 1, 2026. Twenty-seven of them split into more specific children, which is the usual reason a code is deleted. Three did not.
S23.420A, S23.420D and S23.420S, sprain of sternoclavicular (joint) (ligament), were deleted outright. The NCHS Conversion Table, which names the successor for every other new code in the release, lists nothing for them. There is no replacement because no replacement was created.
What Is Left in the Subcategory
| Code | FY 2026 | FY 2027 |
|---|---|---|
| S23.420 | Sprain of sternoclavicular (joint) (ligament) | deleted |
| S23.421 | Sprain of chondrosternal joint | unchanged |
| S23.428 | Other sprain of sternum | unchanged |
| S23.429 | Unspecified sprain of sternum | unchanged |
So the subcategory still exists and still has three usable codes. The problem is that none of them names the joint that was removed.
Why the Remaining Codes Are Not a Clean Substitute
The sternoclavicular joint is where the clavicle meets the manubrium. It is the only bony articulation between the arm and the axial skeleton, and a sprain of it is a distinct injury with its own mechanism, usually a direct blow or a fall onto the shoulder.
Of the three codes left standing:
- S23.421 chondrosternal is a different joint. The chondrosternal articulations are where the costal cartilages meet the sternum. Using it for a sternoclavicular injury names the wrong anatomy.
- S23.428 other sprain of sternum is a residual. It is the honest destination, but it describes the injury as a sprain of the sternum, which loses the clavicular half of the joint entirely.
- S23.429 unspecified sprain of sternum is less specific again.
That is a genuine loss of specificity rather than a renumbering, and it is worth saying plainly because most FY 2027 deletions are the opposite: they exist to add detail. This one removes it.
What This Means in Practice
From October 1, a documented sternoclavicular sprain has to be reported with one of the remaining codes, and S23.428, other sprain of sternum, is the closest available. Nothing about the documentation changes; the record can and should still say sternoclavicular, and the code simply will not carry that detail.
Two practical consequences:
- Do not reach for a shoulder or clavicle code instead. The temptation is to find something that at least mentions the clavicle. A sprain of the sternoclavicular joint is not an acromioclavicular injury and is not a clavicle fracture, and substituting one of those to preserve the word clavicle codes a different injury.
- Any report that counted sternoclavicular sprains stops working. Not gradually, and not with an error. From October 1 the count goes to zero because the code no longer exists, and the cases are inside a residual bucket alongside everything else.
Check the Date of Service, Not the Claim Date
This matters more than usual for a deleted code with no successor, because the instinct on a denial is to find a replacement and resubmit.
S23.420A, S23.420D and S23.420S remain correct for any date of service on or before September 30, 2026, whatever date the claim is submitted. A September injury billed in November still uses them. If such a claim is denied for an invalid diagnosis code, the cause is the payer’s edit table rather than the code, and switching to S23.428 on a September date of service replaces a correct code with a less accurate one.
Common Questions
What replaced S23.420?
Nothing. The NCHS Conversion Table lists no successor for any of the three sternoclavicular codes.
What should I code for a sternoclavicular sprain now?
S23.428, other sprain of sternum, is the closest remaining code. S23.421 is a different joint and should not be substituted.
Can I still bill S23.420A?
Only for a date of service on or before September 30, 2026. It is invalid for later dates of service regardless of submission date.
Is the chondrosternal code a reasonable substitute?
No. The chondrosternal joints are where the costal cartilages meet the sternum, which is a different structure from the sternoclavicular joint.
Were any other FY 2027 deletions left without a successor?
These three are the only ones. Every other deleted code in the release has at least one successor named in the conversion table.
Sources and Methodology
The deletion of S23.420A, S23.420D and S23.420S and the survival of S23.421, S23.428 and S23.429 were confirmed by comparing the complete FY 2026 and FY 2027 ICD-10-CM code descriptions files published by CMS and the CDC National Center for Health Statistics. That no successor exists was established by checking all three codes against the NCHS ICD-10-CM Conversion Table FY 2027, which names a previously assigned equivalent for every other new code in the release. All files are free and none is licence gated. The complete deletion list is in our guide to all 30 deleted FY 2027 codes.
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