Department of Radiology. Institut M T Kassab d’orthopédie. Ksar Said. Tunisia

ULTRASOUND OF MUSCULOSKELETAL INFECTIONS

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

MUSCULOSKELETAL : MK 23

INTRODUCTION

• Musculoskeletal 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 osteomyelitis

•Daily 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 femur is well assessed with US

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

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

Vaso-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 appearance

• A 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.

Osteo arthritis of the first metatarsophlangeal joint. Bone abnormalities such as periosteal new bone formation (*) and perichondral bone erosion (**) are easily assessed by US

* **

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

• Infection of the skin and subcutaneous tissue

• Clinical diagnosis often obvious:

• Sudden onset of local and general

inflammatory closet "orange peel“

• Alteration of general state, fever, ganglia

INFECTIOUS CELLULITIS IMAGING

• Radiographs: nonspecific

• Ultrasound: abscessDiffuse thickening of the skin"dissected appearance" of subcutaneous fat lobulesHyperemia at color Doppler

• CT / MRI:Infiltration of subcutaneous fatHypo T1, T2 Hyper without mass effectEnhancement after contrast injection+ / - Edema of the fascia and adjacent muscles

Radiographs showing thikening

of sucutaneous fat (*).

*

US: soft tissue thickening and Doppler hyperhaemia

soft tissue cellulitis: US shows "dissected appearance" of subcutaneous fat lobules

PHLEGMON AND PYOMYOSITIS

• Pyomyositis: muscle abscess

• Phlegmon: inflammatory infiltration of the muscle not collected before the collected stage

PHLEGMON AND PYOMYOSITISCLINICAL PRESENTATION

• Pain

• Muscle induration

• History of local trauma: from 22 to 67%

• A single muscle group is usually affected

• Careful analysis of adjacent bones and joints to confirm the muscular origin of the infection

PHLEGMON AND PYOMYOSITISIMAGING

• Radiographs : of little use

• Ultrasound:Increased muscle volumehypoechoic septaEvolution towards the abscess with hypoechoic center + / - standard liquid or thin wallsEchogenic wall + / - thick that may contain calcificationsImaging can guide the puncture

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 BURSITIS• Clinical presentation: local inflammatory syndrome

Fever: 40% of cases

• Germ: staph aureus

• X-rays + CT: Swelling of the bursa

• Ultrasound: Thickening of the bursa wall, echogenic content , Doppler

hyperemia

• MRI: staging

Septic bursitis: Ultrasound shows

thickening of the subacromial subdeltoid

bursa wall with color Doppler

hyperemia  and fluid collection

SEPTIC TENOSYNOVITIS

• Often by inoculation

• Staph aureus, tuberculosis

• Fingers and toes flexors

• Radiographs: eliminate arthritis or osteitis

• Ultrasound: thickening of tendon sheath + / - effusion, Doppler hyperemia

• MRI: thickening of tendon sheath, enhancement after contrast injection

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

CONCLUSION

• Ultrasound 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 presentation

• localize the site and extent of infection

• guide drainage or biopsy