Eight Osteomyelitis Codes Deleted, and One Behaves Differently
Other osteomyelitis at M86.8X1 through M86.8X8 was a set of eight codes, one per anatomical site, with no laterality. All eight were deleted on October 1, 2026 and each gained three successors.
Seven of them did the obvious thing. The eighth did not, and if you learn the pattern from the first seven you will code the eighth wrong.
Seven Split by Side
For M86.8X1 through M86.8X7, the sixth character became a laterality digit on the familiar pattern:
| Deleted | Successors | Meaning of the new digit |
|---|---|---|
| M86.8X1 | M86.8X11 / M86.8X12 / M86.8X19 | 1 right, 2 left, 9 unspecified |
| M86.8X2 | M86.8X21 / M86.8X22 / M86.8X29 | |
| M86.8X3 | M86.8X31 / M86.8X32 / M86.8X39 | |
| M86.8X4 | M86.8X41 / M86.8X42 / M86.8X49 | |
| M86.8X5 | M86.8X51 / M86.8X52 / M86.8X59 | |
| M86.8X6 | M86.8X61 / M86.8X62 / M86.8X69 | |
| M86.8X7 | M86.8X71 / M86.8X72 / M86.8X79 |
Nothing surprising. The seventh position sites are paired anatomical structures, so adding right and left is exactly what you would expect from an update that has been adding laterality across the musculoskeletal chapter for years.
The Eighth Splits by Site
| Deleted | Successors | What the digit means |
|---|---|---|
| M86.8X8 Other osteomyelitis, other site | M86.8X80 | Skull |
| M86.8X81 | Face and sinuses | |
| M86.8X89 | Other site |
Two things are different here and both matter.
First, the digits run 0, 1, 9 rather than 1, 2, 9. Anyone applying the laterality pattern mechanically will reach for M86.8X81 expecting right and M86.8X82 expecting left. M86.8X82 does not exist, and M86.8X81 means face and sinuses.
Second, the axis is anatomical site, not side. That is coherent once you see why: the deleted code was other site, a residual, and the skull and the facial bones are not paired left-and-right structures in the way a femur or a humerus is. Splitting them by laterality would have produced meaningless codes. Splitting the residual into skull, face and sinuses, and everything else produces useful ones.
Why This Is a Realistic Error
Deletions with a uniform pattern are the easiest kind to handle: you write one rule and apply it eight times. That is precisely what makes this one dangerous, because seven of the eight reward the rule and the eighth punishes it.
The failure is also quiet. M86.8X81 is a perfectly valid code. A claim reporting it for a right-sided osteomyelitis at an unlisted site will not reject; it will simply record osteomyelitis of the face and sinuses. Nothing flags it and nothing asks.
Osteomyelitis of the skull and of the facial bones are both genuinely reportable conditions, so a record containing them looks entirely plausible on review.
What to Check Before You Bill
- Check the date of service. M86.8X1 through M86.8X8 are valid on or before September 30, 2026 and invalid after it.
- Handle M86.8X8 separately from the other seven. If you wrote a mapping rule, it needs an exception, not an extra row.
- Remember M86.8X82 does not exist. If your system accepts it, your system is wrong.
- Add a laterality prompt for the first seven. The deleted codes had none, so templates written against them will not ask.
- Read the site before choosing within M86.8X8-. Skull, face and sinuses, or other site.
Common Questions
What replaced M86.8X1?
M86.8X11 right, M86.8X12 left and M86.8X19 unspecified, for dates of service on or after October 1, 2026. The same pattern applies through M86.8X7.
What replaced M86.8X8?
M86.8X80 skull, M86.8X81 face and sinuses, and M86.8X89 other site. These are sites, not sides.
Is there a left-side code under M86.8X8?
No. M86.8X82 does not exist. That branch splits by anatomical site.
What if the side is not documented for the first seven?
Use the unspecified code ending in 9.
Why did CMS split the eighth differently?
The deleted code was a residual for other sites, and the skull and facial bones are not paired left-and-right structures, so laterality would not have produced useful codes.
Sources and Methodology
Descriptors for M86.8X80, M86.8X81 and M86.8X89 were read from the FY 2027 ICD-10-CM code descriptions file published by CMS and the CDC National Center for Health Statistics. The successors for all eight deleted codes are as listed in the NCHS ICD-10-CM Conversion Table FY 2027. That M86.8X82 does not exist was confirmed by searching the complete FY 2027 code list. All files are free and none is licence gated. The full FY 2027 deletion list is in our guide to all 30 deleted codes and their replacements.
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