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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5795_Библиотеки_им_академика_М_И_Перельмана.pdf
472
G. Schweintzger et al.
Positioning for DDH Assessment
Different approaches depending on method, most commonly Graf’s technique
is used:
• Graf’s method—baby positioned in lateral decubitus position with slightly bent
hip and inward rotation:
– Specic devices for placing baby and stabilising transducer helpful (to reduce
angulation artefacts).
– Additional stress test for dynamic assessment performed in the same standard
position and section, mandatory in all hips which are not within the physiological range or have a clinical abnormality.
• Similar approach used for femoral head coverage assessment (French approach)
• Dynamic manoeuvre according to Harcke: part of most exams in North America.
– Transverse view in neutral position and with posterior stress.
• Assessment of joint pathology: supine position.
Transducers
High-resolution linear arrays, 18–5MHz (potentially “trapezoid/convex mode”—
phased linear).
Assessment of effusions and pathology in older children: also curved arrays or
phased (“convex mode”) linear arrays, lower frequencies (10–3MHz).
Device Presets
• Hard post-processing with relatively strong contrast/low dB:
– Some prefer grey scale inversion or bicolour mode.
• Image orientation: cranial = right side of monitor image.
– Some turn monitor by 90° to have a somewhat anatomic presentation (up—
cranial) as originally introduced to reect physiological projection similar to
radiograph.
– Some devices allow for ipping the image on display into this above-
mentioned orientation.
• Rarely (not consistent with general recommendations) cranial position dened as
in abdominal US (left upper monitor corner—cranial), e.g. if hip scan performed
after abdominal US.Note that with this orientation the system’s angel measurement software might be confused.
16.2 Examination Technique
16.2.1 Hip US According toGraf
Access from Lateral in Coronal Section
Acquire image in standard plane according to Graf (Fig.16.1):
• Transducer placed over major trochanter in cranio-caudal coronal direction.
16 Neonatal andPaediatric Hip US
Fig. 16.1 Graf standard plane. (a) Schematic drawing of relevant structures, lines and angles for
hip US according to Graf. (b) Typical corresponding US image (standardised projection—upright
position, always projected as right sided)
473
• Then carefully move to parallel sections and rotate on acetabular axis without tilting for imaging the standard plane to be used for diagnosis and measurements.
• Structures to identify on adequate view of acetabular mid portion: lower limb of
bony ilium in depth of acetabular fossa representing physis, middle of acetabular
roof with straight iliac bone line and acetabular labrum (three obligatory landmarks); additionally brief overview of entire joint space should be performed.
Dynamic Assessment
Advisable (normal-appearing hips can be mobile due to laxity of joint capsule after
birth—elastic whipping in normal joint):
• Particularly if suspicious ndings on standard section—mandatory dynamic
assessment.
• Push and pull softly on leg for assessment of stability (femoral head stays well
positioned within joint).
• Instability—displacement of femoral head out of (dysplastic) joint fossa (e.g.
OEGUM/DEGUM recommendation—see: www.OEGUM.at/content/
view/506/210 download “Standarddokumentation der Sonograe der
Neugeborenen- und Säuglingshüfte”):
• In displaced or luxated hips: check for repositionability by respective manoeuvres under US surveillance.
Documentation
Two individually acquired images per hip joint in standard plane:
• One of them must contain measurements (see below, Fig.16.2).
In instable hips, a series of images or video clip showing respective changes dur-
ing stress manoeuvres needs to be documented.
474
Fig. 16.2 Relevant structures, one image without (a) and one with (b) angle measurements.
Patient identication and side mandatory, (gestational) age helpful. (a) 1 transition zone of osseous
to cartilaginous part, 2 femoral head, 3 fold, 4 capsule, 5 cartilaginous labrum, 6 cartilaginous roof,
7 osseous contour of ilium bone, 8 bony rim. (b) 1 base line, 1a auxiliary line, 2 bony roof line, 3
cartilaginous coverage line, α (between line 1 and 2) 65°, β (between 1 and 3) 59°
G. Schweintzger et al.
16.2.2 Modified Graf Classification (Rosendahl)
Objective: classify hip morphology and stability separately, have simpler grading—
more easily and consistently applicable.
Technique: hip morphology (α-angle) assessed in standard coronal view (Graf)
with centred femoral head:
• If hip decentring, eccentric or dislocated hips (Graf 2c, D, 3, 4): femoral head
relocated by mild traction, then thereafter reassess hip morphology.
• Irreducible hip—morphology assessed with dislocated femoral head.
Note Always additional Barlow manoeuvre to assess for coexisting instability even
in morphologically normal hips.
• Stability classication as above.
16.2.3 Hip US According toHarcke
Objective: classify hip stability.
Technique: infant lying supine, transducer positioned over lateral aspect of hip.
Coronal images with hip neutral and in exion, plus posterior lip view.
Transverse images with hip exed with passive abduction and adduction, fol-
lowed by transverse images with stress to evaluate hip stability.
Images must document ndings and need to be labeled appropriately (Fig.16.3a).
abcd
16 Neonatal andPaediatric Hip US
Fig. 16.3 Harcke hip US (image and image with labels). (a, b) Normal hip: normal position of
femoral head on this transverse view. Notice cup-like appearance formed by metaphysis and
ischium. No change with stress manoeuvre. (c, d) Abnormal hip: transverse view of hip with stress
showing subluxation of femoral head from its normal position and disruption of cup-like conguration. This hip was reducible. Abbreviations: F femoral head, M femoral metaphysic, I ischium, T
triradiate cartilage, Arrow cartilaginous labrum
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16.2.4 Femoral Head Coverage According toMorin
(and Modified Morin-Terjesen)
Assesses degree of lateralisation of femoral head based on Harcke’s coronal exion view.
Two lines drawn paralleling Graf’s baseline:
• One tangent to lateral part of femoral head.
• One tangent to medial junction of head and acetabular fossa.
• Measure distance between medial and iliac lines and between medial and lateral lines.
• Calculate ratio multiplied by 100 = % of femoral head covered by bony
acetabulum.
Modied Morin (Terjesen): instead of iliac line, use line through lateral bony rim
of acetabulum parallel to long axis of transducer measuring “bony rim percentage”,
later named “femoral head coverage”.
16.2.5 3DUS forDDH Assessment
Several attempts to use AI and (semi-)automated 3DUS reconstruction algorithms
for presenting hip in standardised fashion (usually using Graf and Rosendahl
approach) and for (semi-)automated measurements. Not introduced into clinical
practice as yet not reliable.
Advantage: possibly more standardised if acquisition done properly—less
dependent on possible angling and tilting errors
Disadvantage: no dynamic scanning possible at present
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G. Schweintzger et al.
16.2.6 Assessment ofJoint Effusion, Capsular Thickening,
Perthes, Arthritis andOthers
US performed in supine position leaving leg in spontaneous position:
• Support of knees helpful to relax—less painful.
Transducer positioned anteriorly along femoral neck; usually slightly lateral to
course of femoral vessels sagittal and parasagittal sections acquired—cross sections
rarely helpful but can be acquired.
16.3 Normal Anatomy
Femoral head is roundish, in neonates cartilaginous—later central echogenic ossication centre appears, varying size depending on age.
Additionally: ossied femoral neck, border zone between cartilaginous and ossi-
ed parts, joint capsule—tracking from femoral neck to acetabulum.
16.3.1 US Criteria inGraf
• Good denition of bony rim.
• Undisplaced cartilaginous roof triangle.
• Normal position of well-covered femoral head in acetabular fossa.
• Iliac bone seen as straight line with clear border to cartilaginous acetabular
labrum—good osseous denition.
• Bony angle (α) >60°, cartilaginous angle (β) <55° (dened below):
– Values can be present at birth but must be reached by 3 months.
Correct section through joint with sufcient depiction of all three landmarks
Note
mandatory for judging hip maturity and for performing angle measurements—if
section taken angulated or too ventral or dorsal (usually recognisable by bent shape
of iliac line or incorrect/missing identication of bony fossa denition), measurements always wrong and diagnostically useless.
16.3.2 Rosendahl Modification
No essential difference from Graf technique with addition of compulsory stress test
(similar to Graf’s “dynamic examination”).
Angle measurements—measured between three lines.
• First line (baseline) from osseous rim of iliac bone in straight line paralleling
osseous iliac contour (Fig.16.4a).
16 Neonatal andPaediatric Hip US
477
a
c
Fig. 16.4 Hip angle measurements and lines (a–d). (a) How the baseline is dened. (b) Denition
of acetabular roof line. (c) Cartilaginous roof line added, with normal angle α and β—not an upright
standard view, increasingly used for practicability and device restrictions; left-hand image is cranial.
(d) Hip US with integrated sonometer software: the software automatically indicates angles (α 54°,
β 78°) and thus hip type (full line) after manual denition of respective lines (immature type II hip,
suboptimal coverage, dynamic assessment shows elastic whipping) not an upright standard view,
increasingly used for practicability and device restrictions; left-hand side on image is cranial
b
d
• Second line (“bony roof line—acetabular roof line”) from inferior rim of iliac
bone as pivot point tangential to bony roof (Fig.16.4b).
• Third line (“cartilage roof line”) from centre of labrum to bony rim, dened as
point where convexity changes into concavity of acetabulum (Fig.16.4c).
Bony angle α: dened between rst and second lines, shows osseous coverage:
• If normal = good (e.g. more than 50%) (Fig.16.4d).
Cartilaginous angle β: measured between rst and third lines, denes site and
conguration of cartilaginous roof:
• If roof at = high β angle—risk of instability (Fig.16.4e).
Note Angle measurements only valid in correctly performed exams.
Small α angle always indicates dysplasia and poor coverage and at least immaturity.
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G. Schweintzger et al.
16.3.3 Normal Findings During Harcke Investigation
• Cartilaginous femoral head positioned in acetabulum as dened by triradiate cartilage centrally and posterior ischium, with femoral metaphysis seen anteriorly.
• No displacement seen with stress—image remains the same, with head centred
in fossa (see Fig.16.3a).
16.3.4 Anatomic Landmarks andNormal Limits forMeasuring
Femoral Coverage
• Lateral part of femoral head, medial junction of head, acetabular fossa.
• Lower normal limits: boys—47%, girls—44%.
16.4 Hip US inOlder Children
Applications and queries: Perthes disease, infection, proximal femoral deciency,
slipped capital femoral epiphysis, trauma, joint effusion.
Normal US ndings:
• Typically longitudinal section, frontal sagittal view.
• Ossied head, neck connected by non-ossied physis—anechoic line.
• Minimal uid within joint space.
• Capsule small, sometimes difcult to delineate.
• Visible contours of acetabulum and femoral head and neck—continuous, without
disruption, smooth and clearly dened surface (Fig.16.5a).
a
c
b
Fig. 16.5 Normal hip (a) in older children—as opposed to hip effusion (b) and septic hip (c). (a)
Normal longitudinal hip US in an older child; normal joint capsule (synovium) appears prominent,
as both layers are collapsed. (b) Simple hip effusion (transient synovitis, extended eld of view):
echo-free uid in widened joint space, thickened capsule. (c) Power Doppler in septic arthritis:
note impressive hypervascularity of thickened synovium, complex uid in widened joint space
16 Neonatal andPaediatric Hip US
479
16.5 Pathologic Findings
16.5.1 Developmental Dysplasia oftheHip (DDH)
Criteria vary depending on method applied (Graf, Harcke, adapted Graf, femoral
head coverage, femoral distance).
Remark/Comment: early detection and treatment = only way for non-invasive
management—important to early recognise DDH to avoid long-term sequelae,
immense healthcare costs, individual morbidity, e.g. by repeated surgery. The debate
of role of screening ongoing in Anglo-American literature; in most of middle
Europe some screening established.
Note Hip US for dysplasia—“nal” investigation (if you miss an endangered hip,
the patient will only come back after years or decades when symptomatic)—strict
and consistent adherence to all quality criteria is essential. As with mammography,
clinical investigation and anamnestic data are mandatory part of every examination.
DDH According to Graf
Strict classication that differentiates between immaturity, dysplasia, instability and
luxation (Table 16.1).
Normal Hip—Type I (described above—“normal ndings”, Figs. 16.1, 16.2,
and 16.4).
Immaturity—Type II
Consider age: depending on subtype, dened by sufcient to poor ossication,
with some rounding of bony rim:
Table 16.1 The Sonometer is a pratical tool for hip classiction, sometimes this or similar graphs
are implemented in US device. A line is drawn betwen the measured alphga and beta angles and
thus the respective hip type (according the Graf classication) is quickly and easily depcitable
480
cd
G. Schweintzger et al.
• Cartilaginous acetabulum usually still covering hip but much wider than osseous
acetabulum:
– Due to ossication decit—covering >half of femoral head.
• Potentially delayed ossication.
Subtypes:
• II a +: physiologic immaturity.
• II a–: maturation decit during rst 3 months.
• II b: after third month of life, α≤60°.
• II c: developmentally dysplastic hip—denitely endangered, needs treatment:
– Dynamic stress manoeuvres are mandatory.
• D (IId)—usually unstable hip with beginning decentring:
– Dynamic stress manoeuvres mandatory.
– Very rounded bony rim.
– Initially displaced cartilaginous acetabulum.
– α = 43°–49°, β > 77°.
– Only treatment option = xation.
Decentred Hip: Type III (Fig.16.6)
US Criteria
Femoral head has pushed cartilaginous acetabular roof cranially:
• Insufcient osseous containment with at bony rim.
• Insufcient bony as well as cartilaginous coverage.
• Decentering of femoral head and cartilaginous acetabulum:
• Type III A—hyaline cartilage hypoechoic.
ab
Fig. 16.6 Pathological hips (Graf classication). (a) Immature hip, slightly rounded roof (>3
months of age—type IIa). (b) Endangered hip: severely rounded bony roof, displaced cartilaginous
roof, dynamic assessment mandatory (type D). (c) Dysplastic—decentred hip with at bony
roof—type III. (d) Luxated hip—by denition cartilaginous labrum compressed between femoral
head and iliac bone (type IV)
16 Neonatal andPaediatric Hip US
481
• Type III B—cartilaginous acetabulum small, compressed, distorted + structural
anomalies + some echoes and inhomogeneous. Only in untreated and chronically
dislocated hips − sign of severe damage (remark: very uncommon in Middle
Europe).
• Therapy: needs repositioning and xation.
Luxated Hip: Type IV (Fig.16.6).
US criteria:
• Femoral head displaced from joint space:
• Luxated in cranial, lateral or dorsal position.
• Cartilaginous acetabulum herniated and displaced caudally:
• Pressed in between femoral head and iliac bone—increased inhomogeneous echoes.
• Sometimes difcult to nd bony rim—reliable measurements often impossible/
not required.
• Dynamic assessment helps to evaluate for repositionability.
Note: wrong angulation will cause wrong results—dedicated instruments are
available to reduce probability of this common pitfall (Fig.16.7)
Results in Rosendahl Modification
According to morphology (using Graf angle discrimination):
• Immature, mildly dysplastic, severely dysplastic.
Using stability: stable, dislocatable, dislocated.
DDH According to Harcke
• Classication: normal, lax with stress, subluxed or dislocated (see Fig.16.3b).
Method more subjective; also includes description of hip stability. Neither
Note
accuracy nor population-based rates of pathological hips based on this technique
have been published.
Hip Assessment Based on Femoral Head Coverage
• All outside accepted limits = DDH—less potential for grading, used as initial
screening tools to assess for normal or abnormal hips.
• In abnormal hips, either Harcke or Graf method can be applied additionally for
treatment decisions.