- Discussion:
- injury involves a combination of ligamentous injury at the inferior portion of the SI joint, and verticle
fracture of the posterior ilium which extends thru the iliac crest;
- the posterior superior iliac spine remain attached to the sacrum;
- often occurs as a part of
lateral compression fractures;
- frx often remains stable to vertical forces because sacrospinous and sarcrotuberous ligaments remain intact;
- this fracture pattern needs to be distinguished from iliac fractures that extend from the iliac crest into the greater sciatic notch,
sparing the sacroiliac joint;
- these iliac fractures may be associated with gluteal vascular injuries;
- Radiographs:
- Operative Managment:
- consider
direct frx fixation from iliac crest into sacrum;
- incision:
- short vertical incision is made 1 fingerbreadth lateral to PSIS;
- subperiosteally dissect the fascia and gluteus maximus off the PSIS and continue the dissection
laterally to expose the fracture;
- frx site is irrigated and debrided of loose tissue;
- reduction and fixation:
-
anterior approach:
- involves plate fixation of the anterior SI joint;
- avoid overcompression of the anterior aspect of the SI joint;
- overcompression causes the posterior portions of the SI joint to become distracted which causes an
internal rotational deformity of the affected hemipelvis;
- this is avoided by appropriate contouring of the plate;
-
posterior approach
- iliac frx is reduced to the PSIS fragment;
- insert two screws (3.5 cortical lag screws or 4.0 mm partially theaded cancellous screws) from posterior to
anterior to maintain the reduction;
- generally two screws are not enough to control rotational forces, and hence a 3.5 reconstruction plate should
be contoured and applied to the outer Iliac table across the fracture site;
The Crescent Fracture: A Posterior Fracture Dislocation of the SI Joint.
J. Borrelli Jr., K.J. Koval, and D.L. Helfet. J Orthop Trauma, Vol. 10, No 3 p 165-170.
