Department of Radiology. Institut M T Kassab dorthopdie. Ksar Said. Tunisia ULTRASOUND OF MUSCULOSKELETAL INFECTIONS

MA KAMMOUN, M CHELLI BOUAZIZ, A MAALEJ, M F LADEB

MUSCULOSKELETAL : MK 23

INTRODUCTIONMusculoskeletal infections are commonly encountered in clinical practice in children and adult patients Radiographs remain the first imaging modality to perform in these conditions Ultrasound (US) may be used either as the primary imaging technique or as an adjunct to radiography, computed tomography (CT), magnetic resonance imaging (MRI) and nuclear medicine studies

OSTEOMYELITIS Acute osteomyelitisDaily US examination allows an early detection of subperiosteal abcess thus indicating surgical treatment (protocol of Tunis). Clinical and US differential diagnosis is sometimes difficult with sickle cell anemia vaso-occusive crisis and subperiosteal haematoma.

Acute osteomyelitis: subperiosteal abcess of the tibia is well assessed with US

Vaso-occlusive crisis. US shows a subperiosteal haematoma of the tibiaVaso-occlusive crisis. US shows a subperiosteal haematoma

OSTEOMYELITIS

Chronic osteomyelitis Soft tissue modifications and /or Juxtacortical collections are assessed with US in acute reactivation of chronic osteomyelitis. Fistula , soft tissue sequestra and cortical bone modifications are also well assessed with US

Chronic osteomyelitis reactivation: Juxtacortical abcess with sequestrum*

Chronic osteomyelitis reactivation: Juxtacortical abcess with a fistula.(*)*Reactivation of a chronic osteomyelitis. US shows cortical bone irregularities and calcifiactions with a soft tissue abcess

ARTHRITIS

In acute arthritis, US shows a joint effusion with or without synovial thickening and local hyperhemia. Bone abnormalities such as periosteal new bone formation or perichondral erosions are also well assessed by US

ARTHRITIS

Chronic arthritis may show a similar appearanceA local amyotrophy around the joint may be observed. Several ultrasonographic signs may help to identify specific infections

ARTHRITIS

The importance of synovial thickening and the presence of thin calcifications into the synovium suggests a tuberculous origin whereas a multicystic appearance is characteristic of echinococcosis

Acute knee arthritis. US shows a joint effusion with synovial thickening

Acute arthritis of the elbow. US Shows a joint effusion without synovial thickening

Acute arthritis of the knee. US shows an important synovial thickening with joint effusion and local hyperhemia.

Tuberculous arthritis of the knee. Note the importance of the synovial thickening and the fine synovial calcification(*). *Echinococcosis of the iliac bone. US shows a characteristic multicystic appearance in the soft tissues.

INFECTIOUS CELLULITIS Infectionof the skin andsubcutaneous tissueClinical diagnosisoftenobvious:Sudden onset oflocal and general inflammatorycloset"orange peelAlteration of general state, fever, ganglia

INFECTIOUS CELLULITIS IMAGING

Radiographs:nonspecificUltrasound:abscess Diffusethickeningof the skin "dissected appearance"of subcutaneousfatlobules Hyperemiaatcolor DopplerCT / MRI: Infiltrationof subcutaneous fat HypoT1,T2Hyperwithoutmass effect Enhancement after contrast injection +/-Edemaof the fascia andadjacent muscles

Radiographs showing thikening of sucutaneous fat (*).*US: soft tissue thickening and Doppler hyperhaemiasoft tissue cellulitis: US shows "dissected appearance"of subcutaneousfatlobules

PHLEGMONANDPYOMYOSITISPyomyositis:muscle abscess

Phlegmon:inflammatory infiltrationof the musclenotcollectedbeforethe collected stage

PHLEGMONANDPYOMYOSITISCLINICAL PRESENTATION

PainMuscle indurationHistory of local trauma:from 22 to 67%A singlemuscle groupis usually affectedCareful analysis ofadjacent bonesandjoints to confirm the muscular origin of the infection

PHLEGMONANDPYOMYOSITISIMAGINGRadiographs: of little useUltrasound: Increasedmusclevolume hypoechoicsepta Evolutiontowards theabscesswithhypoechoiccenter+/-standardliquid orthin walls Echogenicwall+/-thickthat may containcalcifications Imaging canguide thepuncture

Pyomyositis of the thigh: US shows muscle thickening, heterogenous appearance and colour Doppler hyperhemia.

Pyo-myositis in 33 years old man. US shows global thikening of biceps muscle and presence of liquid collection (abcess) into the muscle.

SEPTIC BURSITISClinical presentation: local inflammatory syndrome Fever:40% of casesGerm:staphaureusX-rays+CT:Swellingof the bursaUltrasound:Thickening of the bursa wall, echogenic content,Doppler hyperemia MRI:staging

Septic bursitis: Ultrasound shows thickening of the subacromial subdeltoid bursa wall with color Dopplerhyperemia and fluid collection

SEPTICTENOSYNOVITISOftenby inoculationStaphaureus,tuberculosisFingers andtoesflexorsRadiographs:eliminatearthritisorosteitisUltrasound:thickeningof tendon sheath+/-effusion,Doppler hyperemiaMRI:thickeningof tendon sheath,enhancementafter contrast injection

Tenosynovitis: US shows thickeningof the tendon sheath+/-effusion, Doppler hyperhemiaNote also the presence of little abcesses into the synovial sheath

CONCLUSIONUltrasound is very performant in the diagnosis and follow up of musculoskeletal infections.It allows to: differentiate infection from tumors or non-infective inflammatory conditions with similar clinical presentationlocalize the site and extent of infectionguide drainage or biopsy