Crescent Frx: (Sacroiliac Fracture) : Wheeless' Textbook of Orthopaedics

- Discussion:
- involves a combination of ligamentous injury at inferior portion of SI joint, and verticle fracture of the posterior ilium which
extends thru iliac crest;
- 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 posterior portions of SI joint to become distracted which causes internal rotational deformity
                                 of 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