V04 anatomy class_acetab
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Transcript of V04 anatomy class_acetab
Berton R. Moed, MDProfessor and Chairman, Department of Orthopaedic Surgery
Saint Louis University School of Medicine
Original Authors: Kyle F. Dickson, MD & George V. Russell, Jr., MD, Created March 2004
New Author: Berton R. Moed, MD, Revised January 2007
Radiographic Evaluation, Anatomy and Classification of
Acetabular Fractures
Anatomic Considerations Osteology
• Judet and Letournel– Classification system (JBJS 1964)– Inverted “Y” two column concept (1966)
Osteology
Acetabular Columns
• Anterior (iliopubic) column – Extends from anterior iliac crest
symphysis pubis– 3 segments
• Iliac segment• Acetabular segment• Pubic segment
Acetabular Columns• Posterior (ilioischial) column
– Extends from greater sciatic notch inferior ischium
• The upper end of the posterior column attaches to the posterior aspect of the anterior column forming an angle of about 60 degrees.
• Anatomical roof of the acetabulum forms keystone of arch
Osteology
3D Anatomy of the Innominate Bone
Anterior
Important Vascular Anatomy• Obturator Artery Normal Anatomy (Grant 1962)
– Originates from the internal iliac artery (70%)– Small caliber anastomoses between the obturator
and external iliac systems are common– The pubic branch of the obturator artery commonly
anastomoses behind the body of the pubis with the pubic branch of the inferior epigastric artery
Vascular Anatomy (cont.)• Obturator Artery Abnormal Anatomy
– The obturator artery originates from the inferior epigastric artery or external iliac (30%)
– In a small percentage of cases this anomalous vessel is of large caliber and can result in severe bleeding if it is unknowingly lacerated
– This is the so-called Corona Mortis
Vascular Anatomy (cont.)• Ascending branch of medial circumflex
– Main blood supply to femoral head– Deep to quadratus, obturator internus, and
piriformis, superficial to obturator externus
Vascular Anatomy (cont.)• Can be damaged with
– Dislocation of femoral head– Not leaving 1 cm tag for piriformis and obt.
internus tendons off the greater trochanter– Taking down quadratus from femur instead of
ischium
Vascular Anatomy (cont.)• Superior gluteal artery
– Greater sciatic notch– Can be damaged by aggressive superior or
lateral retraction of the abductor muscles during Kocher-Langenbeck exposure.
Important Neural Anatomy
• Sciatic nerve– Most common traumatic
& iatrogenic nerve injury
– Variable but well described anatomy
Neural Anatomy (cont.)• Superior gluteal nerve
– Greater sciatic notch– Can be damaged by aggressive superior or
lateral retraction of the abductor muscles during Kocher-Langenbeck exposure.
Neural Anatomy (cont.)• Inferior gluteal nerve
– The inferior gluteal nerve branches innervating superior third of the gluteus maximus muscle are located approximately half way between the greater trochanter and the posterior superior iliac spine.
– The nerve can be damaged by extending the Kocher-Langenbeck approach superior to this point within the substance of the gluteus maximus muscle.
Radiographic lines = bone where the x-ray beam is tangential to its surface
Radiographic Evaluation of the
Acetabulum
Radiographic Evaluation
• Anteroposterior pelvis• Judet views• CT scan
AP Radiograph
Landmarks AP View Column
1. Iliopectineal line Anterior
2. Ilioischial line Posterior
3. Radiographic U, or teardrop
Usually Ant.
4. Roof Ant. & Post.
5. Anterior rim Anterior
6. Posterior rim Posterior
AP Pelvic Radiographs • Iliopectineal line
– Anterior 3/4 corresponds to pelvic brim– Posterior 1/4 corresponds to roof of sciatic
buttress– Corresponds to quadrilateral surface
AP Radiograph
AP Radiograph
AP Pelvic Radiographs • Teardrop
– Internal limb = outer wall of obturator canal– External limb = middle 1/3 of cotyloid fossa– Inferior border = ischiopubic notch
Radiographic U orTeardrop
Radiographic U orTeardrop
AP Pelvic Radiographs • Acetabular roof
– Representative of the superior weight bearing area of the acetabulum
• Anterior / posterior walls– Represent lateral extensions of articular
surfaces
AP Radiograph
AP Pelvic Radiographs
• Associated pelvic ring injuries• Bilateral acetabular fractures• Femoral head fractures• Fracture displacement• Congruency of femoral head in
acetabulum
Judet Oblique Radiographs
• Pioneered by Judet and Letournel• 45° oblique pelvic radiographs• Emphasize acetabular columns• Coccyx tip should lie above the center of
the femoral head to ensure adequate rotation
Oblique RadiographsBased on Osteology
AP
Obturator (Internal) Oblique
• Injured side up• Coccyx centered over ipsilateral
femoral head• Obturator foramen in profile• Highlights pelvic brim, anterior column
and posterior wall• Assess congruency of femoral head in
acetabulum
Obturator (Internal) Oblique
Internal Oblique Radiograph
Obturatorforamen
Posteriorwall
Iliac (External) Oblique• Injured side down• Coccyx centered over contralateral femoral head• Iliac wing in profile• Highlights posterior column, anterior wall,
posterior border of innominate bone and quadrilateral plate
• Assess congruency of femoral head in acetabulum
Iliac (External) Oblique
External Oblique Radiograph
Posterior border of innominate bone
Iliac wing
Anteriorwall
Quadrilateralplate
Posteriorcolumn
CT ScanAdditional Information
• Assessment of soft tissue damage• Assessment of solid organ injury• Assessment of hollow organ injury• Assessment of pelvic hematomas
2-D CT Scan
• Acetabular wall fractures• Intra-articular loose fragments • Marginal impacted fragment• Degree of fracture comminution• Position of the femoral head• Femoral head lesions• Joint Congruence• SIJ and the posterior pelvic ring
3mm cuts through pelvis
2-D CT Scan
• Identification of fracture lines not visualized by radiographs
• Orientation of fracture line• Vertical portion of “T” type acetabular
fracture• Rotation of fracture fragments
2-D CT Scan
Case Example
3-D CT Scan
• Provides a good overall picture of the fracture configuration
• The averaging required to produce the image limits the detail and usefulness
• Good for teaching purposes
3-D CT Scan
• Converted from 2 dimensional CT scan data• Image quality determined by software• Allows for subtraction of femur• Allows for rotation of pelvis• All information is on the 2-D CT
Acetabular Fracture Classification
• Classified according to system developed by Judet and Letournel
• Based on the columns and walls of the acetabulum• Two types: Elementary and Associated • Adopted by OTA (Types 62-A, -B & -C) in the
attempt to standardize terminology and to allow for computerized coding
Acetabular Fracture Classification
• Elementary patterns (Part or all of one column fractured)– Posterior wall fracture– Anterior wall fracture– Posterior column fracture– Anterior column fracture
(Plus “by virtue of its purity”)– Transverse
Judet & Letournel Elementary Fractures
Posterior Wall Posterior Column Anterior Wall Anterior Column
Transverse
Acetabular Fracture Classification
• Associated patterns(Include at least 2 elementary forms)– Posterior column & posterior wall fractures– Transverse & posterior wall fractures– T-shaped fractures– Anterior wall or column & posterior
hemitransverse fractures– Both-column
Judet & Letournel Associated Fractures
Posterior Column & Posterior Wall
Transverse &Posterior Wall
T-shaped Both-ColumnAnterior Type withPosterior Hemitransverse
Roof Arc Measurement
• Initially described by Matta 1986• A way to determine if the
remaining intact acetabulum is sufficient to maintain a stable and congruous relationship with the femoral head
• An indicator for nonoperative versus operative treatment
• Measured on all three radiographic views– Medial roof arc > 30° on AP– Anterior roof arc > 40° on
obturator oblique– Posterior roof arc >50° on iliac
oblique• Recommendation:
All roof arcs > 45° if nonoperative treatment is to be considered
Roof Arcs Revised
• Biomechanical Study – Vrahas et al. 1999• Medial Roof Arc < 45 degrees• Anterior Roof Arc < 25 degrees• Posterior Roof Arc < 70 degrees
Roof Arc Example
45 deg
Roof Arc Example
50 deg
Roof Arc Example
50 deg
Roof Arc Example
Three weeks laterIn traction
Examplesof
Fracture Types
Posterior Wall Fractures
• Involves a separation of posterior articular surface
• Majority of the posterior column is undisturbed
• Usually associated with posterior femoral head dislocation
Posterior Wall Fractures• Subtypes
– Fracture confined below the roof– Posterosuperior fracture involving roof– Posteroinferior fracture involving subcotyloid
grove– Fractures associated with marginal impaction
Posterior Wall Fractures
• AP Radiograph– Disruption of posterior rim of acetabulum– Femoral head dislocation
Posterior Wall Fractures
• Judet Radiographs– Obturator oblique
• Highlights posterior wall fracture displacement– Iliac oblique
• Intact posterior column and anterior wall
Posterior Column Fractures• Disruption of ischium• Fracture line originates at greater sciatic
notch travels across retroacetabular surface, exits at obturator foramen
• Ischiopubic ramus fractured• Medial displacement of femoral head
Posterior Column Fractures
• AP Radiograph– Ilioischial line disrupted– Posterior column displaced medially– Iliopectineal line intact
Posterior Column Fractures
• Judet Radiographs– Obturator oblique
• Intact anterior column• Ischiopubic ramus fracture delineated
– Iliac oblique• Highlights posterior column fracture
Anterior Wall Fractures
• Disruption of small portion of anterior roof and acetabulum
• Much of anterior column is undisturbed• Ischiopubic ramus not fractured
Anterior Wall Fractures
• AP Radiograph– Iliopectineal line broken at 2 points – Anterior rim of acetabulum disrupted– Femoral head dislocated anteriorly and
externally rotated– Ilioischial line intact
Anterior Wall Fractures
• Judet Radiographs– Obturator oblique
• Fracture of anterior wall confirmed– Iliac oblique
• Integrity of posterior column confirmed
Anterior Wall Fracture Variant
• Anterior wall equivalent of the posterior wall fracture configuration
• Often shown as the anterior wall fracture rather than that originally described by Judet & Letournel
• Very rare
Anterior Column Fractures• Fracture origination variable
– Several subtypes
• Fracture terminates at ischiopubic ramus
Anterior Column Fractures• Subtypes based on fracture site at
innominate bone– Very low (anterior horn articular surface)– Low (psoas gutter)– Intermediate (anterior interspinous notch)– High (Iliac crest)
Low Intermediate
High
Anterior Column Fractures
• AP Radiograph– Disruption of iliopectineal line– Fracture of the ischiopubic ramus
Anterior Column Fractures• Judet Radiographs
– Obturator oblique• Better illustrates fracture• Demonstrates anterior column displacement
by femoral head– Iliac oblique
• May demonstrate an associated quadrilateral plate fracture
Transverse Fractures
• Fracture through anterior and posterior columns
• Subclassified based on level of fracture through acetabulum
• Often associated with a posterior wall
Transverse Fractures
• Subtypes– Transtectal – fracture through roof of
acetabulum– Juxtatectal – fracture through highest point
of cotyloid fossa– Infratectal – through the cotyloid fossa
Trans-tectal Juxta-tectal Infra-tectal
Transverse Fractures
• AP Radiograph– Iliopectineal line disrupted– Ilioischial line disrupted– Anterior rim disrupted– Posterior rim disrupted
Transverse Fractures• Judet Radiographs
– Obturator oblique• Best demonstrates fracture orientation• Confirms uninjured obturator ring
– Iliac oblique• Demonstrates fracture of quadrilateral
surface• Posterior surface usually greatest
displacement
CT Scans
• Anteroposterior fracture orientation = transverse fracture
• Follow CT proximal & distal to determine size and distinguish transverse fracture from a posterior wall (i.e. looks like a posterior wall fracture but just a transverse)
Posterior Column & Posterior Wall Fractures
• Posterior wall fracture– Same as in elementary patterns
• Posterior column fracture– Fracture begins in cavity created by posterior
wall fracture– Fracture pattern as in elementary patterns
Posterior Column & Posterior Wall Fractures
• Central displacement or dislocation of femoral head
• Displacement of posterior wall usually greater than posterior column
Posterior Column & Posterior Wall Fractures
• AP Radiograph– Disrupted ilioischial line– Disrupted posterior rim– Posterior dislocation of femoral head
Posterior Column & Posterior Wall Fractures
• Judet Radiographs– Obturator oblique
• Intact iliopectineal line• Posterior wall fracture visualized• Direction of the line detaching the posterior column
can be seen which may split the ischium and not involve the obturator foramen.
Posterior Column & Posterior Wall Fractures
• Judet Radiographs– Iliac oblique
• Demonstrates amount of fracture displacement• Demonstrates level of fracture through greater
sciatic notch
Transverse & Posterior Wall Fractures
• Posterior wall component variable• Transverse component extends posteriorly
to notch from the posterior wall fracture• Transverse component as in elementary
patterns
Transverse & Posterior Wall Fractures
• Obturator foramen intact unless associated pelvic fracture
• Judet & Letournel considered the T-shaped fractures with a posterior wall to be a variant of this group
• Rotation similar to transverse– Around vertical symphysis axis and/or– Axis from symphysis to posterior column
fracture exit line in greater sciatic notch
Transverse & Posterior Wall Fractures
• AP Radiograph– All vertical and oblique landmarks of
acetabulum are broken– Posterior hip dislocation common
Transverse & Posterior Wall Fractures
• Judet Radiographs– Obturator oblique
• Obliquity of transverse fracture seen• Integrity of obturator ring confirmed• Size and extent of posterior wall fracture delineated
Transverse / Posterior Wall Fractures
• Judet Radiographs– Iliac oblique
• Integrity of iliac wing confirmed• Fracture through posterior column demonstrated
T-Type Fractures
• Includes all fractures with a transverse fracture of acetabulum with an associated vertical compartment
• Transverse component is identical to pure transverse fracture
• Judet & Letournel considered the T-shaped fractures with a posterior wall component to be a variant of the transverse and posterior wall type
T-Type Fractures
• Roof segment remains attached to iliac wing
• Orientation of the stem of fracture is variable
• Central displacement with anterior and posterior column rotating, around head “saloon door”
T-Type Fractures
• AP Radiographs– All vertical landmarks are fractured– Ischiopubic ramus fracture noted
T-Type Fractures
• Judet Radiographs– Obturator oblique
• Fracture orientation better defined • Fracture of ischiopubic ramus confirmed• Fracture at ischiopubic notch visualized
T-Type Fractures
• Judet Radiographs– Iliac oblique
• Confirms fracture of posterior column• May demonstrate fracture through quadrilateral
surface
Anterior Wall or Column Fracture with Posterior
Hemitransverse Fracture• Anterior wall or anterior column
fracture• Posterior column fractured as in a pure
transverse fracture and usually nondisplaced
• Roof fragment remains attached to iliac wing
Anterior Wall or Column / Posterior Hemitransverse
Fractures• AP Radiographs
– Anterior lesion is as elementary anterior column/anterior wall fracture
– Femoral head follows anterior component– Posterior border of acetabular fracture seen– Disrupts anterior and posterior rim
ilioischial line and iliopectineal line
Anterior Wall or Column & Posterior Hemitransverse
Fractures
• Judet Radiographs– Obturator oblique
• Anterior lesion better defined• Point of rupture of posterior rim
Anterior Wall or Column/ Posterior Hemitransverse
Fractures• Judet Radiographs
– Iliac oblique• Best illustrates direction of posterior fracture line• Highlights iliac wing fracture if present
Anterior Wall or Column/ Posterior Hemitransverse
Fractures• CT Scan
– Medial to lateral (coronal) anterior column fracture line
– Anterior to posterior (sagittal) posterior hemi-transverse fracture line
Both Column Fractures
• Fracture of both columns of acetabulum
• No articular surface remains attached to the axial skeleton
• Central dislocation “Saloon Door”• Spur sign obturator oblique (=
remainder of intact iliac wing)
Both Column Fractures
• AP Radiographs– All 6 acetabular landmarks disrupted– Central dislocation of femoral head– Inward displacement of posterior column– Titled and displaced acetabular roof– Iliac wing fracture– Fracture of ischiopubic ramus
Both Column Fractures
• Judet Radiographs– Obturator oblique
• Iliopectineal line disrupted• Anterior rim of acetabulum broken • Acetabular roof tilted• Posterior rim of acetabulum broken• Fracture of ischiopubic ramus• Spur sign present
Spur Sign
Both Column Fractures
• Judet Radiographs– Iliac oblique
• Anterior rim acetabulum fractured• Iliac wing fractures defined• Displacement of posterior column delineated• Fracture line separating columns seen on
quadrilateral surface
CT Showing Spur Sign Origin
1 2
3 4
* *
* *
Acknowledgment
Kyle Dickson and George V. Russell, Jr. for use of many of their slides from the March 2004 version of this slideshow. Martin Bircher, Emile Letournel, Joel Matta, Tim Pohlemann and Marvin Tile for use of selected slides in both versions.
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