While supplies last! Free 2022 Essentials of Interventional Radiology Coding book with every ICD10monitor webcast order. No code required. Order now >

Osteomyelitis is an inflammation of the bone that typically is further differentiated as acute, sub-acute, or chronic. In ICD-9-CM, documentation of the general site of the inflammation/infection (such as shoulder region, forearm, or ankle), along with identification of the inflammation/infection as a current acute/sub-acute infection or a chronic condition, is all that is required to assign the most specific code.

In addition, acute and sub-acute infections are reported with the same codes (subcategory 730.0), so it is not necessary for the documentation to differentiate between the two. However, in ICD-10-CM, acute, sub-acute and chronic osteomyelitis are divided into additional subcategories – and sub-acute infections are differentiated from acute infections and have their own subcategories.

Acute osteomyelitis is an inflammation of the bone caused by an infectious organism. The condition develops rapidly during the course of several days. It is characterized by localized pain, soft-tissue swelling, and tissue warmth at the site of the infection, plus systemic symptoms such as fever, irritability, fatigue, and nausea. Sub-acute osteomyelitis is differentiated from acute osteomyelitis primarily by a less rapid onset of symptoms and a diminished degree of severity of the symptoms. Symptoms of sub-acute osteomyelitis may include only moderate, localized pain without any systemic issues. Chronic osteomyelitis is a severe, persistent inflammation/infection that can recur and be difficult to treat. A chronic infection also may present with a draining sinus, presenting a greater risk for complications, such as major bony defects.

Acute and Sub-acute Osteomyelitis

There are three subcategories for reporting this condition using ICD-10-CM, including M86.0 Acute hematogenous osteomyelitis, M86.1 Other acute osteomyelitis, and M86.2 Sub-acute osteomyelitis. Acute hemotogenous osteomyelitis results from an infection at a remote site. The infectious organism then is carried through the bloodstream to the bone. The most common infectious organism is Staphylococcus aureus. In children, the most common sites of infection are the long bones of the extremities, and in adults the most common sites are the lumbar vertebrae. Acute osteomyelitis also may result from direct inoculation of the bone, with the infectious organism creating issues as a result of an open wound, an open fracture, or an invasive surgical procedure. Direct inoculation osteomyelitis is reported with codes from subcategory M86.1.

Chronic Osteomyelitis

There are four subcategories in ICD-10-CM for chronic osteomyelitis, including M86.3 Chronic multifocal osteomyelitis, M86.4 Chronic osteomyelitis with draining sinus, M86.5 Other chronic hematogenous osteomyelitis, and M86.6 Other chronic osteomyelitis.

Chronic multifocal osteomyelitis is a rare condition that also is referred to as chronic recurrent multifocal osteomyelitis, or SAPHO syndrome (synovitis, acne, pustulosis, hyperostosis, osteitis). The cause of the condition is unknown, and tissue cultures typically fail to identify any infectious organism. The condition predominantly affects children, although it also is seen in adults. It is characterized by multiple areas of bone inflammation, and the predominant localized symptom is a deep, aching pain. When the inflammation is present in the lower extremities, gait is affected. Fever also may or may not be present. Chronic, multifocal osteomyelitis may be accompanied by skin changes, including acne, psoriasis, and pustules on the palms of the hands and soles of the feet.

The other three subcategories for chronic osteomyelitis report hematogenous and direct inoculation types, with category M86.3 being a combination code that captures chronic types (in which a draining sinus has developed).

Other Osteomyelitis

There are two additional subcategories for the reporting of this condition in ICD-10-CM. Subcategory M86.8 reports other osteomyelitis, and this category includes Brodie’s abscess. Brodie’s abscess previously was classified as a type of chronic osteomyelitis, but most scholarly literature now refers to it as a sub-acute condition. The defining characteristic is the presence of a bone abscess surrounded by dense fibrous tissue and sclerotic bone. Subcategory M86.9 reports unspecified osteomyelitis.

Site Specificity in ICD-10-CM

While ICD-9-CM identifies only the general region of the osteomyelitis, ICD-10-CM includes specific bones for some sites and laterality. Specific sites for subcategories M86.0-M86.6 include:

  • Shoulder
  • Humerus
  • Radius/ulna
  • Hand
  • Femur
  • Tibia/fibula
  • Ankle/foot
  • Other specified sites
  • Multiple sites




Other osteomyelitis (M86.8) which includes Brodie’s abscess, requires only the general region (shoulder, upper arm, forearm, hand, thigh, lower leg, ankle/foot, other site, and unspecified site). Laterality is not a component of codes in category M86.8. Unspecified osteomyelitis (M86.9) is not specific to a site.

Additional Codes

As with all infectious processes in which the infectious agent is not a component of the code that describes the condition, an additional code from categories B95-B97 should be assigned to identify the infectious agent, assuming it can be identified. Any major osseous defects also should be identified with a code from subcategory M89.7.

Additional Coding Changes for Bone Infections

One additional coding change is that there are is no longer a separate designation for periostitis without mention of osteomyelitis in ICD-10-CM. In ICD-9-CM, this condition was reported with codes from subcategory 730.3. In ICD-10-CM, the Alphabetic Index provides only a limited number of specific entries for periostitis. There are specific entries for periostitis of the dentoalveolar structures and jaw, and for periostitis due to certain infectious organisms, including gonorrhea, syphilis, tuberculosis, and yaws.

For all other types, the Alphabetic Index instructs the coder to “see also osteomyelitis”. This means that a diagnosis of acute hematogenous periostitis due to methicillin-susceptible S. aureus would be reported with a code from subcategory M86.0, and code B95.61 would be reported secondarily to identify the infectious organism.

About the Author

Lauri Gray, RHIT, CPC, has worked in the health information management field for 30 years. She began her career as a health records supervisor in a multi-specialty clinic. Most recently she has worked as a clinical technical editor of coding and reimbursement print and electronic products. She has also taught medical coding at the College of Eastern Utah. Areas of expertise include: ICD-10-CM, ICD-10-PCS, ICD-9-CM diagnosis and procedure coding, physician coding and reimbursement, claims adjudication processes, third-party reimbursement, RBRVS and fee schedule development. She is a member of the American Academy of Professional Coders (AAPC) and the American Health Information Management Association (AHIMA).

Contact the Author


To comment on this article please go to editor@icd10monitor.com


You May Also Like

Leave a Reply

Your Name(Required)
Your Email(Required)