CHRONIC OSTEOMYELITIS

Discussion

OSTEOMYELITIS Osteomyelitis is defined as an inflammation

of the bone caused by an infecting organism

The infection may be limited to a single portion of the bone or may involve numerous regions, such as the marrow, cortex, periosteum, and the surrounding soft tissue.

The infection generally is due to a single organism, but polymicrobial infections can occur, especially in the diabetic foot.

OSTEOMYELITIS: CLASSIFICATIONS Traditional System (accdg. to time of

onset) Acute: 2 weeks Subacute: weeks to months Chronic: 3 months

OSTEOMYELITIS: CLASSIFICATIONS Waldvogel System (accdg. to

etiology and chronicity) Hematogenous Arising from contiguous infection (no

vascular disease present) Vascular disease present Chronic

OSTEOMYELITIS: CLASSIFICATIONS Cierney and Mader System (accdg. to

anatomic extent of infection and physiologic status of host) 1: Medullary only (acute hematogenous) 2: Superficial cortex (contigous spread or

soft tissue trauma) 3: Localized (cortical and medullary,

mechanically stable) 4: Diffuse (cortical and medullary,

mechanically unstable)

OSTEOMYELITIS: CLASSIFICATIONS

OSTEOMYELITIS: CLASSIFICATIONS Cierney and Mader System (accdg.

to anatomic extent of infection and physiologic status of host) A: Healthy host B: Compromised host▪ Bs: due to systemic factors▪ Bl: due to local factors▪ Bls: due to local and systemic factors

C: Treatment worse than disease

CHRONIC OSTEOMYELITIS Difficult to eradicate completely

Though systemic symptoms may subside, foci in the bone may contain infected material, infected granulation tissue or a sequestrum

Intermittent acute exacerbations may occur and responds to rest and antibiotics

Hallmark: infected dead bone within a compromised soft-tissue envelope

CHRONIC OSTEOMYELITIS The infected foci within the bone are

surrounded by sclerotic, relatively avascular bone covered by a thickened periosteum and scarred muscle and subcutaneous tissue This avascular envelope of scar tissue

leaves systemic antibiotics essentially ineffective

CHRONIC OSTEOMYELITISSecondary infections are

common Sinus tract cultures usually do not

correlate with cultures obtained at bone biopsy

Multiple organisms may grow from cultures taken from sinus tracks and from open biopsy specimens of surrounding soft tissue and bone

CHRONIC OSTEOMYELITIS Generally requires aggressive

surgical excision combined with effective antibiotic treatment

Surgery is not always the best option, however, especially in compromised patients

CHRONIC OSTEOMYELITIS: DIAGNOSIS The diagnosis of chronic osteomyelitis

is based on clinical, laboratory, and imaging studies

Gold standard: biopsy specimen for histological and microbiological evaluation of the infected bone Staphylococcal in most causes, especially

posttraumatic Anaerobes and gram-negative bacilli may

also be seen

CHRONIC OSTEOMYELITIS: DIAGNOSIS Physical examination:

Integrity of skin and soft tissue Determine areas of tenderness Assess bone stability Evaluate neurovascular status of limb

CHRONIC OSTEOMYELITIS: DIAGNOSIS Laboratory studies:

Generally nonspecific and give no indication of severity▪ Elevated ESR and CRP▪ Elevated WBC in 35%

CHRONIC OSTEOMYELITIS: DIAGNOSIS Radiologic studies:

Plain radiographs▪ Soft tissue edema and loss of fascial planes

(earliest signs of bone infection)▪ Cortical destruction (7 to 10 days)▪ Periosteal reaction (2 to 6 weeks)▪ Sequestrum: dead bone (6 to 8 weeks)▪ Involucrum: sheath of periosteal new bone (6

to 8 weeks)

SEQUESTRUM AND INVOLUCRUM Cortical penetration and

accumulation of inflammatory exudates periosteal stripping inner layer stimulated to form bone later infected “barrier” is formed cortex and spongiosa deprived of blood supply necrosis sinus tract formation in some case

Small sequestra may be resorbed or may be extruded through sinus tract

CHRONIC OSTEOMYELITIS: DIAGNOSIS Radiologic studies:

Technetium-99m Scanning▪ Increased uptake in areas of increased blood

flow and osteoblastic activity Gallium Scanning▪ Increased uptake in areas of leukocyte and

bacteria accumulation (can therefor be used to monitor response to surgery)

CHRONIC OSTEOMYELITIS: DIAGNOSIS Radiologic studies:

CT Scan▪ Provides excellent definition of cortical bone and a

fair evaluation of the surrounding soft tissues and is especially useful in identifying sequestra

MRI▪ Provides a fairly accurate determination of the

extent of the pathological insult by showing the margins of bone and soft-tissue edema▪ May reveal a well-defined rim of high signal

intensity surrounding the focus of active disease (rim sign)

TREATMENT

Generally cannot be eradicated without surgical treatment Debridement Curettage Sequestrectomy

Goal: eradicate infection by achieving a viable and vascular environment

Reconstruction after adequate surgery and appropriate antibiotic therapy

TREATMENT

Limb is splinted until wound is healed Will also prevent pathologic fractures

Antibiotic regimen is continued from prolonged period and should be monitored by IDS

TREATMENT Polymethylmethacrylate Antibiotic Bead Chains

Delivers levels of antibiotics locally in concentrations that exceed the minimal inhibitory concentrations

Antibiotic is leached from the PMMA beads into the postoperative wound hematoma and secretion, which act as a transport medium

Aminoglycosides are the most commonly employed antibiotics for use with PMMA beads

Can be used in the treatment of osteomyelitis if soft-tissue coverage is impossible after initial débridement

TREATMENT

Biodegradable Antibiotic Delivery Systems A second procedure is not required to

remove the implant Soft Tissue Transfer

Fills dead space left behind after extensive débridement

Ilizarov Technique Allows radical resection of the infected bone

Hyperbaric Oxygen Therapy