Sacrum and Sacral Fractures

- See:
     - Posterior Pelvic Injury:
     - Sacroiliac Fracture Dislocations:
     - Sacral Stress Fractures:

- Anatomy of Sacrum:

- Classification:
    - zone I:
           - frx across sacral ala can cause L5 nerve root impingement;
           - about 6% of these patients will have neurological injuries;
           - ref: Direct anterior decompression of L4 and L5 nerve root in sacral fractures using the pararectus approach: a technical note.

    - zone II:
           - frx thru neuroforamina can cause unilateral sacral anesthesia;
           - frx involving the neural foramina require operative debridement of frx fragments prior to reduction and fixation
                      (through posterior approch);
           - ref: Zone 2 sacral fractures managed with partially-threaded screws result in low risk of neurologic injury
    - zone III
           - frx thru body of sacrum can cause highest incidence of injury to cauda equina and result in neurogenic bladder;
           - about 56% of these patients will show neurological injuries
           - ref: Functional outcomes of Denis zone III sacral fractures treated nonoperatively.
    - misc:
           - transverse fractures;
           - U shaped fractures:
                 - results from axial loading;
                 - radiographs:
                       - bilateral transforaminal sacral fractures and irregularities, L5 transverse process frx;
                       - paradoxic inlet view: on standard AP view, the upper sacrum appears as inlet view;
                 - ref: Percutaneous stabilization of U-shaped sacral fracture using iliosacral screws: technique and early results

- Associated Injuries:
    - if the sacral fracture is impacted w/ no verticle displacement, it may represent a LC fracture (therefore look for
             anterior pelvic injury);
    - w/ vertical displacement, the sacral frx may represent a Malgaine frx equivolent;


- Physical Exam:
    - displacement in vertical plane is diagnosed by applying one hand to pelvic iliac crest and using other to apply traction to leg which
           should cause displacement in vertical plane;

- Radiology: (see outlet view);
    - sacral arcuate lines:
           - will help delineate anatomy of frx of upper sacrum;
           - sacral arcuate lines are composed of inferior surfaces of costal elements that form roofs of anterior sacral canals (foramina) &
                    neural grooves;
           - arcuate lines are easily visible on AP view of pelvis & are symmetrical;
           - asymmetry or discontinuity of sacral arcuate lines may be caused by uncomplicated sacral fracture ;
           - disorganized or marked disruption of sacral arcuate lines is indicative of comminuted sacral fracture;

- CT scan:

                  - ref: Pelvic X-ray misses out on detecting sacral fractures in the elderly - Importance of CT imaging in blunt pelvic trauma.  

- Determine Frx Stability:
      - stable fracture includes impacted vertical fracture of sacrum, nondisplaced fracture of posterior sacroiliac complex; or subtle
            fracture of upper sacrum as seen by asymmetry of sacral arcuate lines;
      - unstable frx, is characterized by frx diastasis of more than 0.5 to 1 cm, along w/ an unstable anterior injury;
      - the other question, however, is the amount of healing potential;
            - if a type I fracture reduces w/ traction, then the unstable frx would be expected to become sticky in about 4 weeks and would
                       expect complete healing in 3 months; 
      - references:
            - OTA highlight paper predicting future displacement of nonoperatively managed lateral compression sacral fractures: can it be done?
            - Nonoperative immediate weightbearing of minimally displaced lateral compression sacral fractures does not result in displacement.
            - Conservative management of transverse fractures of the sacrum with neurological features. A report of four cases.
            - Bilateral Sacral Ala Fractures Are Strongly Associated With Lumbopelvic Instability

- Surgical Approach to Fractures of the Sacrum:
    - patient is in the prone position on a flouro table;
    - similar surgical approach used for posterior approach to the SI joint
    - posteror incision is made;
    - additional vertical incision is made on opposite side;
    - sacral nerve roots & frx site are visualized by placing laminar spreader at frx site or between the two superior ilac crests;
    - decompression:
           - decompression of sacral foramina (laminectomy) is helpful for patients w/ neurologic impingment;
    - reduction:
           - sacral frx reduction is usually achieved w/ pointed reduction forceps.
           - forceps should span from spinous processes of sacrum to iliac crests;
           - assess reduction by visualization of posterior sacral lamina & palpation of the fracture through the greater sciatic notch;
           - sacral nerve roots are palpated after the reduction to be certain that they have not been entrapped;
    - fixation:
           - obtained w/ one or two screws into S1 vertebral body placed from lateral surface of the iliac wing; (similar to
                  SI joint dislocation);
                  - using flouroscopy, insert long 6.5 mm cannulated lag screws engage frx from the iliac wing to the body of S1;
           - with transforaminal fractures, use fully threaded screw to avoid compression of the sacral neural foramina
           - it may be possible to place a thin malleable plate placed across posterior sacrum from ilium to ilium as a tension band just
                  above greater sciatic notch;
    - Sacroiliac Joint Fixation - Posterior screw fixation:
           - it is important to note that malreduction of transforaminal sacral fractures will substantially decrease the space
                    available for iliosacral screws;
           - surgeon should make all efforts to reduce transforminal fractures to within 1 cm of being anatomic;
           - references:
                    - The effect of sacral malreduction on safe placement of iliosacral screws. Reilly et al. (15th Meeting of OTA  1999). 
                    - Small bowel obstruction from entrapment in a sacral fracture stabilized with iliosacral screws: case report and review of the literature.
                    - The incidence of and factors affecting iliosacral screw loosening in pelvic ring injury.

   - 4.5 mm reconstruction plate: (Albert, et al (1993));
          - indicated for posterior pelvic fractures as well as sacral fractures;
          - reconstruction plate is placed along dorsum of the sacral and through the posterior iliac spines (transiliac plate fixation);
          - patient is placed in the prone position;
          - two incisions are made over the PSIS which are perpendicular to the iliac wings, and one vertical incision is made over
                  base of the S1 spinous process;
                  - dissections are caarried down to the bony surfaces;
          - predrill the PSIS to assist w/ reconstruction plate insertion;
                  - use the 4.5 drill to make 2-3 drill holes 1 cm lateral to the PSIS;
          - an appropriately sized 4.5 mm reconstruction plate is chiseled thru the iliac spine, passed along the dorsum of the sacrum
                  to the opposite PSIS;
          - recon plate is appropriately contoured;
          - plate is fixed to the iliac wings using 6.5 mm cancellous screws, w/ two screws inserted into each ilac wing;
          - reference:
                 - Posterior Pelvic Fixation Using a Transiliac 4.5 mm Recon Plate: a clinical and biomechanical study

Sacral fractures: an important problem. Retrospective analysis of 236 cases.

Transverse fractures of the sacrum. A report of six cases.

Occult sacral fractures in osteopenic patients.

The effect of sacral fracture malreduction on the safe placement of iliosacral screws.

Triangular osteosynthesis of vertically unstable sacrum fractures: a new concept allowing early weight-bearing.

Surgical Anatomy of the Sacrum

Sacral Fractures: Current Strategies in Diagnosis and Management

Open Reduction Internal Fixation of Displaced Sacral Fractures: Technique and Results 

Can Lumbopelvic Fixation Salvage Unstable Complex Sacral Fractures?

Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Tuesday, November 26, 2019 11:51 pm