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V01 anatomy class_pelvis
1. Radiographic Evaluation,
Anatomy, and Classification of
Pelvic Ring Injuries
Kyle F. Dickson, MD
Chief of Orthopaedics, Charity Hospital
Director of Orthopaedic Trauma
Tulane University
Created March 2004
Revised April 2007
23. Pelvic Ring
• No inherent stability
• Ligaments give the pelvis stability
24.
25. Symphyseal Ligaments
• Resist external rotation in double-leg stance
• Rami act as struts to resist compressive and
internal rotation in single leg stance
• Sectioning causes little pelvic instability
26. Ghanayem, J Trauma 1995
• Abdominal wall contributes to pelvic
stability (laparotomy increased pelvic
displacement in cadaveric model)
29. Sacrum
• Inlet View Reverse keystone where
compression forces displace sacrum
anteriorly
• Outlet View True keystone compression
locks sacrum into pelvic ring
• Small rotating movements during gait
30. Posterior Ligaments
• Ant. SI Joint – resist external rotation
• Post. SI and Interosseous – posterior
stability by tension band (strongest in body)
• Iliolumbar ligaments augments posterior
complex
31. Sacrotuberous (sacrum behind sacro-
spinous into ischial tuberosily vertically)
Resists shear and flexion of SI joint
Sacrospinous – (anterior sacral body to
ischial spine horizontally) resists external
rotation
32. Normal SI Joint Motion with Gait
• < 6 mm of translation
• < 6° rotation
• Intact cadaver resist 5,837 N (1,212 lbs)
33. Nachemson, Acta Orthop Scand
1966
• Sitting 710 N (160 lbs) at each Si joint
• Lying 196 N (44 lbs)
• Lateral decubitus 686 N (154 lbs)
• Standing 980 N (220 lbs)
34. Sitting or Double Leg Stance
• Pubic rami tension and compression
posteriorly
• External rotation injury – displaces in
sitting or double leg stance
35.
36. Single Leg Stance
• Tension shear posteriorly and compression
of rami
• Will displace internal rotation injury
38. Stability – ability of pelvic ring
to withstand physiologic forces
without abnormal deformation
39.
40. Translational Deformities
• X axis – Diastasis or impaction
• Y axis – Caudad or cephalad displacement
• Z axis – Anterior or posterior displacement
41. Rotational Deformities
• X axis – Flexion or extension
• Y axis – Internal rotation or external
rotation
• Z axis – Abduction or adduction
42. Deformity of Pelvis
• Defined from an anatomically positioned
pelvis in space
• Deformity a combination of rotational &
translational deformities
43. Deformity of Pelvis (cont.)
• Does not deform around a single point but
can be represented as a vector from a
normally positioned pelvis
• Acute deformity difficult to measure but
direction often able to be determined
44. Pelvic Instability
• These injuries which will have worsening
deformity
• Physical exam and radiographic evaluation
45. Determining Stability
• Integrity of posterior bone and ligament,
unstable = vertical plane displacement
• Some partial instability in rotation
46. Physical Exam
• Symmetrical palpable ASIS, iliac wing, and
symphysis
• ASIS compression test
• Iliac wing compression test
57. Placement of Wires Show
• Ant. SI joint lateral to post. SI
• Radiographic brim does not always
correlate with anatomical brim
58.
59.
60.
61.
62.
63. CT Scan
• Better defines posterior injury
• Amount of displacement versus impaction
• Rotation of fragments
• Amount of comminution
• Assess neural foramina
64. Radiographic Signs of Instability
• Sacroiliac displacement of 5 mm in any
plane
• Posterior fracture gap (rather than
impaction)
• Avulsion of fifth lumbar transverse process,
lateral border of sacrum (sacrotuberous
ligament), or ischial spine (sacrospinous
ligament)
65. Classification
• Aids in predicting hemodynamic instability
• Aids in predicting visceral and g.u. injuries
• Aids in predicting pelvic instability
• Aids in understanding mechanism of injury,
force vector of injury, and surgical tactic for
reduction
66. Classification Systems
• Anatomical (Letournel)
• Stability & Deformity (Pennal, Bucholz,
Tile)
• Vector force and associated injuries (Young
& Burgess)
73. OTA/AO – Pelvic Injury
Classification
• 61A – Lesion sparing (or with no
displacement of ) posterior arch
• B – Incomplete disruption at posterior arch;
partially stable
• C – Complete disruption of posterior arch;
unstable
74. A Fractures – Ring Intact
• A-1 – Fracture of innominate bone;
avulsion
• A-2 – Fracture of innominate bone; direct
blow
• A-3 – Transverse fracture of sacrum and
coccyx
84. Young and Burgess, Rad 1986
• Increases clinicians diagnosis of frequently
missed lesions
• Predictive index for associated injuries
• Helps clinicians to select treatment based on
probable pathology and hemodynamic
status
85. Lateral Compression
• LC-1 – Ant. superior inf. rami or symphysis
and compression of sacrum same side
• LC-2 - LC-1 – anteriorly and posteriorly
crescent fracture near anterior border at SI
joint → Ileum rotated internally
88. Patient WH
• Progressive IR deformity that became fixed
• Required anterior release & post sacral
osteotomy followed by external rotation
• Pre-& postop, AP and inlet, and 2 year
follow-up
101. LC (cont.)
• LC-3 – Windswept pelvis – LCI or II on
one side of the pelvis and open book (APC)
on contralateral side (roll over mechanism
by IR on LC side and ER on contralateral
side)
104. Anteroposterior Compression
• Diastasis anteriorly through symphysis
pubis or vertical Rami fractures
• Posteriorly usually through SI joint –
amount of displacement defines subset
105. Anteroposterior (cont.)
• APC-1 – 1-2 cm symphysis diastasis and
minimal SI diastasis anteriorly (external
rotation of hemipelvis – stable pelvis).
120. Patient NJ
• VS initially attempted to be treated with
anterior plate and ex-fix with hardware
failure
• 3 stage pelvic reconstruction ( ant. →
post→ ant. 2 yr follow-up – Auburn
football player)
136. Acknowledgment
Return to
Pelvis
Index
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Questions/Comments
If you would like to volunteer as an author for
the Resident Slide Project or recommend updates
to any of the following slides, please send an e-
mail to ota@aaos.org
Joel Matta, Phil Kregor, and Mark
Vrahas for the use of their slides
