Bone & joints


Chronic osteomyelitis

Last author update: 28 July 2022
Last staff update: 7 February 2023

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PubMed Search: Chronic osteomyelitis

Mohammad Khurram Minhas, M.B.B.S.
Nasir Ud Din, M.B.B.S.
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Cite this page: Minhas MK, Ud Din N. Chronic osteomyelitis. website. Accessed September 21st, 2023.
Definition / general
  • Longstanding infection of bone lasting months to years; characterized by low grade inflammation and presence of dead bone or fistulous tract
Essential features
  • M:F = 4:1
  • Incidence is highest in adults, 41 - 50 years (29%)
  • Most common site: tarsal and metatarsal bones and toes (43%)
  • Most common organism: Staphylococcus aureus; responsible for 80 - 90% of cases
  • Contiguous spread osteomyelitis is most common
ICD coding
  • ICD-10: M86 - osteomyelitis
  • Overall age and sex adjusted annual incidence of osteomyelitis is 21.8 cases per 100,000 person years (J Bone Joint Surg Am 2015;97:837)
  • M:F = 4:1 (Sci Rep 2018;8:14895)
  • Incidence is highest in adults, 41 - 50 years (29%); attributed partly to higher frequency of traumatic injury in this population
  • Chronic nonbacterial osteomyelitis most commonly affects children
  • Diabetes is also associated with higher incidence (Sci Rep 2018;8:14895)
  • Unifocal disease (94%):
    • Tarsal and metatarsal bones and toes (43%)
    • Femur and tibiofibular (20%)
    • Spine, sternum and pelvis (19%)
    • Others: craniofacial, upper limb bones, jaw (J Bone Joint Surg Am 2015;97:837)
  • Localization within a bone:
    • Acute hematogenous osteomyelitis in infants and adults affects the epiphysis
    • In neonates and children, transphyseal blood vessels facilitate direct extension into the adjacent joint as the metaphysis is intra-articular in this age group
    • In children, the infection is usually limited to the metaphysis
    • In the spine, infection localizes to the subchondral regions of the vertebral body (Diagn Histopathol 2016;22:355)
  • Entry of the organism into bone occurs by 3 main mechanisms:
    • Osteomyelitis secondary to a contiguous focus of infection (after trauma, surgery or insertion of a joint prosthesis) is most common
    • Secondary to vascular insufficiency (e.g., diabetic foot)
    • Hematogenous seeding, least common
  • Acute suppurative inflammation and tissue necrosis
  • Vascular compromise leading to bone necrosis
  • Sequestration
  • Progression:
    • Spread toward an intracapsular location may lead to septic arthritis
    • Spread toward a subperiosteal location may lead to periosteal elevation
  • Extension of sequestrum and necrotic material through cortical bone may create a fistula and ultimately break through the skin (Lancet 2004;364:369)
  • Contiguous spread osteomyelitis: single or multiple organisms including Staphylococcus aureus, Streptococcus species and Actinomyces; most common in adults
  • Secondary to vascular insufficiency: Staphylococcus aureus, Staphylococcus epidermidis, E. coli, Klebsiella pneumonia, Proteus spp. and Pseudomonas aeruginosa
  • Hematogenous osteomyelitis: Staphylococcus aureus is responsible for 80 - 90% of cases; most common in children (J Bone Joint Surg Am 2015;97:837, Diagn Histopathol 2016;22:355)
  • Mycobacterial infection
  • Treponemal infection, fungal infection, helminth infection (uncommon)
Clinical features
  • Patients with chronic osteomyelitis often have a protracted course
  • Fever, pain and swelling, depending on site involved
  • These patients may report interval acute episodes
  • Patient can also present with open wound that exposes fractured bone or an indolent draining fistula (Lancet 2004;364:369)
  • Laboratory:
    • Bone biopsy is essential for diagnosis
    • Microbiological cultures for bacteria, mycobacteria and fungus are required for appropriate treatment (Lancet 2004;364:369)
  • Imaging studies:
    • Plain Xray: for initial diagnosis and follow up
    • Ultrasound: for initial diagnosis
    • CT scan and MRI: for initial diagnosis (Lancet 2004;364:369)
Radiology images

Contributed by Nasir Ud Din, M.B.B.S.
Epiphyseal osteomyelitis

Epiphyseal osteomyelitis



Periosteal reaction

Periosteal reaction



Prognostic factors
  • Diabetes is a poor prognostic factor in patients with chronic osteomyelitis; poor prognosis in patients with nutritional and systemic diseases
  • Complications: arthritis, pathological fractures, skeletal deformities, amyloidosis, malignant transformation (squamous cell carcinoma), pseudocarcinomatous squamous hyperplasia involving bone (rare)
  • Reference: Diagn Histopathol 2016;22:355
Case reports
  • Antibiotic therapy
  • Surgical therapy (debridement, saucerization, sequestrectomy, continuous intramedullary irrigation)
  • May require myocutaneous flaps
  • Foreign material (e.g., infective implant) needs to be removed with temporary stabilization, occasionally with antibiotic beads or cement with subsequent reimplantation
  • Nonsteroidal anti-inflammatory drugs and bisphosphonates for chronic nonbacterial osteomyelitis
  • Reference: Lancet 2004;364:369
Clinical images

Images hosted on other servers:

Chronic osteomyelitis with wound infection

Microscopic (histologic) description
  • Necrotic bone
  • Inflammatory infiltrate rich in plasma cells
  • Fibrosis, variable
  • Granulomas, in cases of tuberculosis or fungal infection
  • Reference: Diagn Histopathol 2016;22:355
Microscopic (histologic) images

Contributed by Nasir Ud Din, M.B.B.S. and Mohammad Khurram Minhas, M.B.B.S.
Area of suppurative necrosis Area of suppurative necrosis

Area of suppurative necrosis

Chronic granulomatous osteomyelitis Chronic granulomatous osteomyelitis

Chronic granulomatous osteomyelitis

Sample pathology report
  • Tibial lesion, biopsy:
    • Features are consistent with chronic nonspecific osteomyelitis; clinical and radiological correlation is recommended (see comment)
    • Comment: Microscopy reveals fragments of necrotic bone and fibroconnective tissue exhibiting dense inflammation and abscess formation. Inflammatory infiltrate comprises of neutrophils, plasma cells, lymphocytes and some foamy histiocytes. Negative for malignancy.
Differential diagnosis
  • Langerhans cell histiocytosis:
    • Polymorphous inflammatory infiltrate, rich in eosinophils
    • Characteristic polygonal cells with vesicular nuclei with nuclear grooves
    • Neoplastic cells are immunoreactive for S100 and CD1a immunostains
  • Rosai-Dorfman disease:
    • Extranodal involvement is common and may also affect bones
    • Histologically, shows histiocyte proliferation
    • Histiocytes in Rosai-Dorfman disease exhibit emperipolesis, the nondestructive phagocytosis of lymphocytes and erythrocytes, which is the hallmark of the disease and required for diagnosis
    • These cells are positive for S100 immunostains and are negative for CD1a
  • Plasma cell neoplasia:
    • Bone based lytic lesions
    • Histologically composed of a monoclonal population of plasma cells with variable cytological differentiation
    • Absence of neutrophils
    • Monoclonal, as demonstrated by light chain restriction and serum immunoelectrophoresis
  • Hodgkin and non-Hodgkin lymphoma:
    • These lymphomas can secondarily involve bone
    • Non-Hodgkin lymphoma can be primary
    • Hodgkin lymphoma shows mixed inflammatory infiltrate, like in chronic osteomyelitis; however, there will be large atypical mononuclear and binucleated Reed-Sternberg cells, which will stain positive for CD30, CD15
    • Non-Hodgkin lymphomas histologically contain atypical lymphoid cells
  • Ewing sarcoma:
    • Tumor is composed of sheets of small round blue cells
    • Tumor cells are positive for MIC2 (CD99), FLI1 and NKX2.2 immunostains
Board review style question #1

A 25 year old man presented with pain around the knee joint. Xray studies were suggestive of a neoplastic lesion. The lesion was biopsied (image above) and it shows which of the following histologies?

  1. Chronic osteomyelitis
  2. Diffuse large B cell lymphoma
  3. Ewing sarcoma
  4. Metastatic carcinoma
  5. Plasma cell neoplasm
Board review style answer #1
A. Chronic osteomyelitis

Comment Here

Reference: Chronic osteomyelitis
Board review style question #2
The most common pathogen in chronic osteomyelitis is

  1. Escherichia coli
  2. Klebsiella pneumonia
  3. Mycobacterium tuberculous
  4. Staphylococcus aureus
  5. Staphylococcus epidermidis
Board review style answer #2
D. Staphylococcus aureus

Comment Here

Reference: Chronic osteomyelitis
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