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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5790_Библиотеки_им_академика_М_И_Перельмана.pdf
408
11 Small Part and Hip Ultrasound
NOTE : In osteoarthritis of infants, there may be distention and consecutive luxation
and osseous defects. Luxation can be recognised by applying DDH US techniques
(e.g. Graf’s criteria) – search for it!
11.2.1.3 Hip Osteoarthritis
US fi ndings similar to any other joint.
Usually unilateral, whereas transient synovitis may occur on both sides, as well
as – rarer – Perthes disease.
Particularly after long-standing and bacterial arthritis, defects may remain – with
poor ossifi cation of femoral neck and defects in convexity of femoral head. Thus it
is important to assess and monitor development of disease – persisting effusion
always hints towards an underlying condition or Perthes, where osseous defects can
also/additionally be seen.
11.2.2 (Femoral Head) Epiphysiolysis/Slipped
(Capital Femoral) Epiphysis
US superior to plain fi lm in infants due to poor ossifi cation of femoral head –
improved assessment, same approach accounts for all other joints with cartilaginous
epiphysis (e.g. shoulder, elbow – birth trauma) (Fig. 11.7 ):
• Displacement in any direction – US access from different directions and positions
recommended.
US Findings
Typically anechoic cartilage of femoral head with or without ossifi cation centre
slipped:
• Continuity of bone margin disrupted at level of physis – step-off phenomenon.
• One millimetre displacement equals approximately 5° displacement on plain
fi lm.
• Complex joint fl uid representing haemorrhagic components – particularly in
acute phase.
Fig. 11.7 Epiphysiolysis in a newborn after birth
trauma. Note discontinuity between ossifi ed bone
and hypoechoic cartilaginous epiphysis indicating
dislocation of epiphysis
11.2 Other Conditions of Hip Joint
409
• Periosteal reaction – late stage.
• Secondary changes of surrounding soft tissues.
NOTE : If tolerated, dynamic assessment may reveal pathologic motion at phy-
sis. Same criteria apply to epiphysiolysis of any other joint in neonates and
infants.
US-guided reposition feasible.
11.2.3 Perthes Disease
Defi nition
Avascular necrosis of femoral head of unclear aetiology, in 20 % of affected
children history of transient synovitis of hip.
US Findings and Staging
Grade I:
• Potentially only joint effusion.
• Slight asymmetric reduction in height of epiphysis as well as femoral head on
affected side.
• Contour of femoral head is maintained.
Grade II (Fig. 11.8 ):
• Fragmentation; irregular disruption of outer contour of bony femoral head –
sonographically irregular.
• There may be secondary effusion.
Grade III and IV:
• Reparative mechanisms – femoral head increasingly homogeneous.
• Signifi cantly reduced head height.
• Joint effusion diminishing.
• However, lateralisation and atypical contour of remodeled femoral head
persists.
a
Fig. 11.8 Perthes disease. ( a ) Scattered epiphysis of femoral head in early Perthes disease (stage
II). ( b ) Both hips imaged for comparison (split image technique): note reduced height of affected
right ( R ) femoral head (Grade IV – US appearance varies with stage); additional imaging compul-
sory (plain fi lm + MRI)
b
410
11 Small Part and Hip Ultrasound
11.3 Investigation of Bones, Joints, Tendons
11.3.1 Requisites and Technique
Transducers and Techniques
• Linear transducers with high resolution (17/12–5 MHz). Features such as trape-
zoid mode, image compounding and harmonic imaging helpful.
• In very superfi cial structures stand-off pad helpful.
• For deeper structures, curved linear arrays and lower frequencies helpful – as
trapezoid mode of linear transducers usually lacks same penetration.
• For long structures such as tendons, extended view techniques helpful, alterna-
tively split/dual image technique.
• In tumours or infl ammatory conditions (abscess, arthritis, etc.): CDS helpful.
• Elastography – promising future method for assessment of tendons and tumours,
but not yet validated in children.
Positioning and Handling
• Varies depending on affected area, therefore no standard planes.
• Important to choose comfortable position that minimises pain.
• Start investigation at non-painful area, work to area of disease – in young chil-
dren consider applying analgesic ointment before investigation.
TIP : Very often initial evaluation of contralateral normal side proves valuable –
serves as intraindividual normal reference, helps optimise equipment settings and
enables child to get used to scanning (reducing anxiousness and fear).
• All joints and pathologies usually assessed in two orthogonal sections.
• Surface alterations better visualised and documented by 3DUS using surface
rendering.
Indications
Applicable to acute and chronic conditions:
• Joint pain or effusions (most commonly used in large joints but also feasible in
small joints).
• Skin, soft tissue, muscular and tendon disease (e.g. Achilles tendon, shoulder
capsule, wrist and foot tendons).
• Evaluation of unclear swelling, e.g. suspected haematoma versus other causes
for bumps.
• Suspected tumorous conditions with lumps.
• Search for and detection of foreign bodies.
• Assessment of all accessible osseous structures (e.g. continuity or focal disruption,
callus).
• Evaluation of periosteal reaction – exquisitely visualised by US, particularly
periosteal thickening and abscess.
• Assessment of all accessible peripheral muscles (e.g. follow structures from ori-
gin to insertion, show transition zone to tendon or bone).
Advantage : US allows comprehensive assessment of all surrounding structures
(bones, joints, etc.) and perfusion (CDS).
11.3 Investigation of Bones, Joints, Tendons
411
Disadvantage : If very painful – diagnostic benefi t may be restricted in some areas –
may not justify US; imaging then performed by plain fi lm, CT or MRI.
Restrictions : Deeper joint spaces and bony structures beyond surface not visual-
ised by US – commonly need MRI.
NOTE : In osseous structures, usually only surface component (cortex) assessable
for continuity or disruption, e.g. fracture or tumour. If US can penetrate cortical
layer (e.g. due to disruption or reduced ossifi cation/calcifi cation by tumour infi ltration, osteomyelitis and decalcifying disease), visualisation of processes in deeper
bone compartments achievable. Detailed demonstration of all major joints and
their US appearance beyond scope here – refer to extended literature and
textbooks.
Different for non-ossifi ed parts of skeleton in younger age: US ideal for showing
cartilaginous structures = primary imaging approach. US shows continuity of cartilaginous parts with ossifi ed bone and/or other surrounding structures – particularly
useful in diagnosing epiphysiolysis or for assessing children with nonaccidental
injuries (corner fractures, etc.).
11.3.2 Typical Normal Findings
Bone
If US beam perpendicular, and cortical layer of normally ossifi ed bone intact: only
surface echo seen as an echogenic border with complete shadowing behind. Subtle
layer seen in front: represents periosteum.
NOTE : Pseudo-periosteal layer may occur if gain too high producing strong
refl ections.
Cartilaginous Structures
• Hyaline cartilage: usually anechoic/hypoechoic with more or less echoes within,
depending on maturity (and setting of US system) (Fig. 11.9a ).
• Collagenous (fi bro-) cartilage: US appearance becomes more echogenic in areas
of more fi brous components (e.g. fi brous annulus of vertebral disc, acetabular
labrum of newborn and infant hip).
• Ossifi cation centres become centrally echogenic, with increasing shadowing
(Fig. 11.9b ).
Remark : Cartilaginous echostructure and contour usually show slight irregularity at
transition zone to ossifi ed bone (may represent physis). However, even with this
short disruption, surface usually remains continuous.
Joint Capsule and Tendons
• Depending on angle of insonation, these structures change echogenicity and
appearance (anisotropy).
• Capsules usually have just one visible layer except for insertion (varies with
transducer frequency and resolution).
• Tendons have several parallel echogenic layers.
412
11 Small Part and Hip Ultrasound
ab
Fig. 11.9 Cartilaginous epiphysis in infants. Hypoechoic cartilaginous epiphysis with some stip-
pled physiologic echoes representing the venous sinusoids – without ( a ) and with ( b ) central echo-
genic ossifi cation centres causing shadowing
11.3.3 Pathologic Findings
11.3.3.1 Fracture
• Interruption of cortical contour (high sensitivity).
• Additional fi ndings: periosteal reaction, haematoma, later callus formation can
be seen, depending on phase/age of fracture (Fig. 11.10 ):
– If dual/split image/extended view techniques or 3DUS used: angle measure-
ments can be performed to defi ne deviation of displaced fracture, provided
longitudinal axis of respective bone clearly identifi ed.
• In all fractures: periosteal reaction, calcifi cation and callus formation seen as
(pseudo-) tumorous, more or less ossifi ed, formation at site of fracture.
• In reparative phases: CDS can show hypervascularity and hyperemia as sign of
reparative processes; diffi cult to distinguish from tumorous or infl ammatory
conditions.
• Growing fractures and pseudo-arthrosis can be visualised – particularly when
performing dynamic study showing not only disruption and distraction of frac-
ture ends but also painless mobility towards each other.
NOTE : US cannot replace plain radiographs. Plain fi lm simpler and allows clearer
defi nition of dislocation angles. US demonstration and documentation of entire
bone may be cumbersome. But specifi c applications exist where US is very helpful
due to restrictions of plain fi lm: e.g. skull fractures, corner fractures and toddlers
fractures (Fig. 11.11 ).
• Fractures and dislocation of cartilaginous bone = US domain – much better than
plain fi lm, also used for image(US-)-guided reduction, e.g. after epiphysiolysis
(see Fig. 11.7 ).
Remark : In long bones, usually only the part of fracture close to transducers can be
visualised and assessed, as US cannot penetrate healthy ossifi ed bone. If one needs
to see entire circumference – scan from every direction. Therapeutic insonation can
11.3 Investigation of Bones, Joints, Tendons
413
a
c
b
Fig. 11.10 Subperiosteal haematoma. ( a ) Typical early image appearance of traumatic haema-
toma due to fracture with dislocation. ( b ) Extended view US depicts huge haematoma after rupture
of calf muscles; measurements taken – also of small complex-liquid defect. ( c ) DDx: osteomyelitis
– subperiosteal abscess may appear similar on US as subperiosteal haematoma
increase callus formation and bone healing (by causing hyperemia) – requires specialised equipment.
11.3.3.2 Joint Effusion
US extremely helpful, with high sensitivity.
Simple Effusion
Sonographically defi ned by usually anechoic fl uid (uncomplicated effusion) within
joint space, causing widening of joint and enlargement of joint space.
Commonly capsule appears normal, may be slightly thickened (see
Fig. 11.5b ).
Complicated Effusion
Echoes within fl uid, potentially sedimentation (see Figs. 11.5c , 11.12 ,
and 11.13 ).
NOTE : US not specifi c to aetiology or content of effusion (haemorrhagic, protei-
nous, infectious, etc.). Diagnosis of underlying disease only in combination with
414
11 Small Part and Hip Ultrasound
a
bc
Fig. 11.11 US in fractures. ( a ) Fracture without destruction of periosteum and slight bending. ( b )
Subtle skull fracture poorly depictable by plain fi lm; note regional haematoma. ( c ) Impressive
callus formation after femur fracture
clinical context (trauma, infl ammation, aseptic necrosis) and laboratory
evaluation.
Only those parts of joint assessable where US can access. Therefore – to properly
assess joint for potential effusion – scan all around joint accessing joint space from
different directions not to miss focal effusion in specifi c compartment, recess or
bursa.
• US used for guided diagnostic arthrocentesis and drainage (see Chap. 2 ) .
11.3.3.3 Arthritis
Effusion commonly seen; small amounts detectable by careful examination.
Typical US feature (high sensitivity, low specifi city): thickening of joint capsule
with more or less hyperemia on CDS (Figs. 11.13a and 11.5b ).
NOTE : Etiological correlation by US not possible (needs history, physical exam,
laboratory fi ndings, etc.).
• In rheumatoid conditions capsular thickening can become irregular and nodular,
with varying amount of hypervascularisation (Figs. 11.13b and 11.5c ) – US used
to guide therapy and assess therapeutic response, also for drug instillation (see
Chap. 2 ) .
11.3 Investigation of Bones, Joints, Tendons
ab
Fig. 11.12 Joint effusion with septations (knee arthritis). Relatively clear fl uid, some thickening
of joint capsule in rheumatoid arthritis, some nodular components indicating pannus formation in
longitudinal ( a ) and axial ( b ) sections
abc
415
Fig. 11.13 Thickened joint capsule ( a ) and hyperaemia on CDS ( b ). ( a ) Septic knee arthritis –
with marked thickening of capsule and complex fl uid. ( b ) Thickened elbow joint capsule with
effusion (osteoarthritis). ( c ) CDS depicts hypervascularisation (same joint as b )
11.3.3.4 Trauma
Most commonly, US used to assess disruption of tendons, muscles, bony structures
(see above) and apophyseal avulsions in adolescents (Fig. 11.14 ).
NOTE : In these conditions, do not only assess tendon or joint but also surrounding
structures and muscles which may show haematoma or disruption (see respective
chapter) (Fig. 11.10a, b ).
Haematoma
• More or less ovoid-shaped mass, with varying echogenicity (Fig. 11.10a, b ).
• Appearance varies with age, site and kind of haematoma (diffuse bleed into pre-
served structures, haematoma without preserved structures) and insonation
angle.
• Old haematoma either resorbs completely, leaves some fi brous scarred tissue or
forms seroma (more or less complicated fl uid collection with some capsule-like
wall), may calcify or even ossify (myositis ossifi cans) then show complete or
punctuated internal echogenicities with posterior shadowing (see below).
416
11 Small Part and Hip Ultrasound
a
c
b
Fig. 11.14 US in musculoskeletal trauma. ( a , b ) Apophyseal avulsion on right side ( left part of
image) – comparison to contralateral normal left anterior inferior iliac spine using split image
technique: ( a ) cross section, ( b ) longitudinal scan in a different patient with same pathology. ( c )
Partial rupture of Achilles tendon: tendon swollen, hypoechoic, disruption of continuity clearly
depictable
Rupture of Tendon
Extremely rare in paediatric population; dynamic investigation very helpful for ligamentous queries and function assessment, as well as defi ning compartment and origin/connections.
• Complete tear : continuity of tendon disrupted, often signifi cant distance between
lower and upper part (measure distance for treatment decisions) – ends diffi cult
to fi nd and assess.
• Partial tear : persisting continuity of some parts of tendon, though potentially
swollen and altered, whereas other parts are disrupted with some sort of hema-
toma formation (Fig. 11.14b ).
• Chronic tear / chronic microtrauma – different image appearance: organisation
and reparative processes = inhomogeneous small spots with some calcifi cations
appear in somewhat unusually and inhomogeneously structured tendon. Tendon
may be thickened and edematous – altered echotexture. If tendon sheet intact,
there may be thickening and effusion due to chronic alteration with variable
hyperemia and hypervascularisation (CDS).
• Elastography promises to become a useful tool for detecting areas of chronic
damage.
11.3 Investigation of Bones, Joints, Tendons
417
ab
cd
Fig. 11.15 Baker cyst and DDx of soft tissue cysts. ( a , b ) Baker cyst (+ + 2 ) longitudinal ( b ) and
cross section ( a ), the latter showing the connection to joint space (+ +
masses: “cystic lymphangioma” – cystic lymphatic/vascular malformation. ( d ) Abscess formation
in breast with reactive changes in surrounding soft tissue
1
). ( c ) DDx in complex cystic
11.3.3.5 Cysts
Number of situations with soft tissue cysts – potentially connected with joints space
– e.g.:
• Posttraumatic and chronic stress, seroma remnants; effusion-fi lled recesses and
bursae.
• Physiological variations/fl uid-fi lled recessus.
• Cystic tumours.
• DDx: even in uncomplicated cysts – evaluate if connected to joint space
(e.g. Baker cyst), tendon sheath (e.g. ganglion), muscle (e.g. posttraumatic
seroma) or vessel (ectasia or aneurysm) (Fig. 11.15 ).
NOTE : An irregular, thickened and hypervascular wall or complicated echoic content (with potential sedimentations) usually indicates complications – such as
infl ammation or tumorous origin.
11.3.3.6 Inflammation
US extremely helpful for differentiating superfi cial versus deep soft tissue infection
(e.g. fasciitis). Used for depiction of necrosis or abscess and differentiation of other
causes.
NOTE : Increases index of suspicion in early phase of osteomyelitis (see
below).