Infection 2.2

Osteomyelitis

-Refers to the suppurative form of bone/marrow infection

What is the most common organism in osteomyelitis?

-Staphylococcus auerus

Can you tell the type of organism on imaging?

-No, but some are more common in certain scenarios (Salmonella in sickle cell anemia & Pseudomonas in intravenous drug users)

Population at risk for osteomyelitis?

-Immunocompromised

-Alcoholics

-Newborns

-Intravenous drug users

-Diabetics

-Patients on hemodialysis

-Post surgical patients

Osteomyelitis is common in what age of patients?

-2 to 12 years old (Males more than females)

Most common pathway of spread for osteomyelitis?

-Hematogenous spread

Clinically presentation of osteomyelitis

-Pediatric: acute systemic symptoms

-Adults: variable can be subtle

-Swelling

-Malaise

-Fever

-Elevated ESR, CRP, WBC

Common locations of Osteomyelitis

-Lower limb > Spine (lumbar most common) > Radius > SI

What part of the bone is most common in osteomyelitis?

-Metaphysis (unless under 1 then it’s epiphysis)

Latent period for Osteomyelitis visualization in extremities?

-7 to 10 days

Latent Period for Osteomyelitis visualization in spine?

-21 days

Acute/Early Imaging features of Osteomyelitis

-Soft tissue swelling

-Aggressive bone destruction

-Periosteal reaction (laminated or spiculated)

Laminated Periosteal reaction Indicating Osteomyelitis on X-ray (Acute)

Acute Phase of Osteomyelitis on X-Ray

Brodie Abscess (Subacute Osteomyelitis)

-Localized, possible aborted form of suppurative osteomyelitis

-Staph is most common organism that causes this

-Most common in the tibia

-Geographic lucent lesion with variable sclerosis

Clinical Presentation of Brodie Abscess

-Night pain relieved by aspirin (ddx w/ osteoid osteoma)

Brodie Abscess on X-ray

Brodie Abscess on X-ray #2

Sequestrum Formation in Chronic Osteomyelitis

-Necrotic infected bone surrounded by granulation tissue

-Harbors active infection and can cause recurrence of infection if not removed

Involucrum in Chronic Osteomyelitis

-Periosteal envelop attempting to grow over the infection

Cloaca in Chronic Osteomyelitis

-Opening from the diseased bone into the soft tissues

Sinus Tract in Chronic Osteomyelitis

-Opening from the soft tissues to the hollow viscera or surface of the skin

Chronic Osteomyleitis general imaging features?

-Sclerosis

-Solids, wavy, irregular periosteal new bone formation

-Cortical thickening

-Possible superimposed osteolysis

Osteomyelitis showing malignant degeneration can lead to?

-Squamous cell carcinoma

Sequestrum (Chronic Osteomyelitis) on X-ray

Involucrum (chronic osteomyelitis)on X-ray

Septic Arthritis

-Most common in a single joint

-Most common due to hematogenous spread or direct extension

-Staphylococcus aureus most common organism

Where is direct extension in septic arthritis common in?

-The foot

Clinical Presentation of Septic Arthritis

-Chills

-Fever

-Edema

-Pain

-Erythema

-Elevated ESR, CRP, and WBC

Most common places for Septic arthritis

-Knee and hip

Imaging Features of Septic Arthritis

-Joint effusion
-Displaced fat pads and distention
-At hip, waldenstrom’s sign (>11mm total or 2.0mm difference between sides)

-Rapid loss of joint space and destruction of subarticular cortex (white line at joint margin will disappear)

-Can show osteomyelitis

-Bony ankylosis and growth disturbances possible

Septic arthritis on X-ray

Fight Bite on X-ray (Septic arthrtitis)

TB Spondylodiscitis on X-ray

Pyogenic Spondylodiscitis

-Acute suppurative infection of the spine

-Almost always involves a disc and 2 adjacent vertebra

-Pediatric: Implants in the disc and moves into the vertebra

-Adult: begins in the anterior superior/inferior corner at the endplate and invades the disc

-Most common in lumbar

-Staphylococcus aureus organism is most common

Clinical Signs of Pyogenic Spondylodiscitis

-Signs of systemic infection

-Pinpoint tenderness or dull ache throughout region

-Elevated ESR,CRP, WBC

Imaging Features of Spondylodiscitis

-21 day radiograph period

-Early destruction of endplate and loss of disc height

-Progression to destruction of anterior vertebral body

-Paraspinal abscess or phlegmon possible

-Does not often show subligamentous spread

Pyogenic Spondylodiscitis on X-ray

Tuberculosis

-Caused by mycobacterium tuberculosis

-Has primary and secondary stages

-Hematogenous is the most common form of spread (batson’s venious plexus)

Primary Tuberculosis

-Pulmonary infection that resembles lower respiratory infection/pneumonia

-may remain silent for remainder of patient’s life

Secondary Tuberculosis

-AKA post-primary

-Reactivation of organism, typically in immunocompromised, causes severe pulmonary destruction and may spread to other organ system

Osseous Involvement in tuberculosis is in what population?

-2 to 30 years of age

Most common location of Tuberculosis Spondylodiscitis (Potts disease)

-Spine (Thoracolumbar mainly)

Septic Tuberculosis is most common in?

-Hip

Tuberculosis Spondylodiscitis Imaging Features

-Radiographic latent period of 21 days

-Early:
-Disc space loss occurs but is minimal
-Anterior vertebral body/endplate destruction
-Subligamentous spread
-Propensity to skip levels

Late:
-Pathologic vertebral collapse (gibbus deformity)
-Retorpharyngeal, paravertebral, psoas abscess (cold abscess & Snowflake sign)

Phemister’s Triad

-Progressive slow joint space narrowing

-Juxta-articular osteopenia

-Peripheral erosions of the articular surface

Tuberculosis Arthritis

-Phemister’s Triad

-Rice bodies (chronic synovitis causes shedding of synovium with relatively uniform size/shape loose bodies)

-Loss of subchondral bone and lytic destruction

-In the knee can show a widened intercondylar notch, enlarged condyle, and osteopenia

Scrofula

-Lymph node involvement, often in cervical lymph nodes (tubeculosis)

Cold Abscess

-Large abscess without classic severe inflammation (tuberculosis)

Snowflake Sign

-Calcification throughout a cold abscess (tuberculosis)

Pott Disease

-Spinal involvement in tuberculosis

Gibbus Deformity

-Acute angulation of the spine due to collapse

Spina ventosa

-Tuberculosis dactylitis with expansile osseous lesion

Pott Puffy Tumor

-TB of the skull (frontal bone) with scalp abscess

Weaver Bottom

-Subgluteal tuberculous bursitis with direct extension into the ischium

Classic TB Spondylodiscitis

-Lytic destruction and osteopenia in the anterior vertebral body adjacent to the endplate with early sparing of the disc and subligamentous spread to multiple levels

Pott’s Disease on X-ray

Pott’s Disease w/Gibbus deformity on X-ray

Tuberculosis Dactylitis on X-ray

Pott Puffy Tumor on Imaging

Mycotic Osteomyelitis

-non-suppurative

-Very similar to tuberculosis in clinical and radiographic manifestation

Most common Mycotic INfections

-Coccidiomycosis

-Actinomycosis

-Candida albicans

-Aspergillosis

-Blastomycosis

Coccidiomycosis

-Most common in San Joaquin valley(California, Nevada, and Mexico)

-Typically a respiratory infection nearly identical to TB

-Predilection for boney prominences

-Associated with desert rheumatism

Desert Rheumatism

-Erythema nodosum

-Polyarthritis

-Fever

Maduramycosis

-Most common fungal osteomyelitis

-Chronic fungal infection of the foot (madura foot)

-Melting snow appearance

Madura Foot on X-ray

Syphilitic Osteomyelitis

-Caused by Treponema pallidum

-Presents a congenital or acquired (part of Torch)

Congenital Syphilis

-Transmitted to fetus via the placenta after the 4th month of gestation

-symptoms usually manifest in the first 4 months of life but often not diagnosed until >10 years of age

-Osseous most common at knees, shoulders, and wrist

Hutchinson Triad

-Hutchinson’s teeth

-Interstitial keratitis

-Deafness

Imaging Features of Congenital syphilis Metaphysisitis

-Bilateral symmetric
-Lucent metaphyseal bands similar to leukemia and neuroblastoma metastasis
-Irregular fragmented (sawtooth) metaphysis at growth plate
-Wimberger’s sign (Eccentric erosive change at the proximal medial tibia bilaterally

Imaging Features of Congenital Syphilis Periostitis

-Symmetric laminated periostitis that is often widespread (DDX with HOA and hypervitaminosis A)

Imaging Features of Congenital Syphilis Osteitis

-Extension of metaphysitis into the diaphysis, reactive sclerosis, and asymmetric overgrowth of involved bone (can cause saber shin)

-Regions of focal or poorly defined lysis

Clutton’s Joints

-Painless swelling of a joint (knees most common)

Syphilitic Dactylitis

-Swelling in digits resembling spina ventosa of TB

Acquired Syphilis

-Most common in skull, tibia, and clavicles (frontal bone)

-Osseous manifestations seen in tertiary syphilis

Imaging features of Acquired Syphilis

-Diffuse periostitis that may lead to increased thickness and altered contour of bones

-Lytic destruction that may be focal and well-circumscribed or permeative

Wimberger Sign on X-ray (Syphilis)