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Reduction, fixation strategies aid management of vertical shear pelvic ring injuries
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Vertical shear pelvic ring injuries present a unique challenge due to their inherent vertical and rotational instability. Binders, sheets or external fixators may at times underestimate the severity of initial displacement or mask associated occult injuries. Preoperative CT is necessary for adequate planning based on patient anatomy and injury characteristics. We present our preferred method of treatment for vertical shear pelvic ring injuries and focus on the surgical technique.
Vertical shear (VS) pelvic ring fractures represent a subgroup of high-energy injuries, characterized by both vertical and rotational instability. Patients must be managed according to the Advance Trauma Life Support algorithm and resuscitation protocols. The initial anteroposterior (AP) pelvic radiograph commonly depicts the extent of initial injury before pelvic binders, sheets or external fixators are placed. VS injuries may result from either bony or ligamentous injury. The treating surgeon must be diligent in assessing for sacroiliac (SI) joint diastasis or pelvic fracture. Once the patient is hemodynamically stabilized, the treating surgeon may plan for definitive fixation. Basic principles must be followed, but treatment strategies are variable for these rare and complex injuries. In this article, we highlight our typical methods for reduction and fixation.
During preoperative planning, CT imaging (Figures 1 and 2) is useful to identify bony anatomy and safe corridors; length and diameter of screws; sacral comminution; sacral dysmorphism; and inlet and outlet angles for intraoperative fluoroscopic images.
Figure 2. Sagittal CT of the posterior pelvis demonstrates an inlet view of about 22° from vertical.
Figure 3. The AP pelvis view shows vertical displacement of the patient’s right hemipelvis.
Figure 4. Shown is the inlet pelvis view with posterior displacement of the right hemipelvis.
Figure 5. Shown is placement of distal femoral traction.
Figure 6. The obturator inlet view of the right hemipelvis shows placement of a Schanz pin.
Figure 7. Intraoperative placement of a Thompson retractor is shown.
Figure 8. The inlet view shows the pubic symphysis with Jungbluth retractor placement.
Figure 9. A lateral view shows the sacrum with guide wire placement at S1 and S2 starting points.
Figure 10. The obturator inlet view of the contralateral ilium shows wire contacting the far lateral cortex.
Figure 11. Shown is the outlet view with a 7.3-mm cannulated drill for lag by technique in the S1 segment.
Source: Cyril Mauffrey, MD, FACS, FRCS
Reduction techniques
Reduction can be achieved with either open or closed means. Most VS injuries can be treated posteriorly by indirect or percutaneous means. The anterior ring may require open reduction and internal fixation or closed reduction and external fixation. Typically, the injured hemipelvisis displaced proximally and posteriorly (Figures 3 and 4).
With the patient supine, a distal femoral traction pin is placed in the affected extremity and connected to 20 pounds to 40 pounds of weight (Figure 5). This reduces proximal migration of the hemipelvis. Posterior displacement is corrected with placement of a supra-acetabular 5-mm Schanz pin and traction pulled in a posterior-to-anterior direction (Figure 6). A Thompson retractor (Figure 7) can be attached to the table in a sterile fashion with external fixator clamps and bars using the patient’s body weight to reduce the posterior translation in a hands-free technique. This system may be also used for counter-traction of the uninjured hemipelvis.
Figure 13. The outlet view is shown with a 7.3-mm fully threaded cannulated SI screw in the S1 segment prior to final compression.
Figure 14. The outlet view is shown with a 7.3-mm fully threaded cannulated TSTI screw in the S2 segment with final compression.
Figure 15. An obturator inlet view of the ipsilateral ilium confirms washer contact to near the ilium.
Further indirect reduction of the posterior ring is achieved with open reduction of the anterior ring. A Pfannenstiel approach is used with the patient supine and a Foley catheter in place. Provisional reduction is held with a Jungbluth clamp (Figure 8).
Open reduction of the posterior ring is usually not required. It is reserved for cases in which closed reduction has failed. An open approach in the prone position is recommended in cases with significant sacral comminution, particularly with suspected nerve injury or incarcerated fragments impinging on the neural foramina. In these cases, fixation is accomplished with a posterior tension band plate or lumbopelvic fixation. Fracture reduction can include the use of a posterior superior iliac spine external fixator system, femoral distractors or direct clamp placement.
Figure 17. Outlet view of pubic symphysis is shown with reduction and hardware placement.
Figure 18. Shown is the postoperative AP pelvis.
Figure 19. Shown is the postoperative outlet pelvis.
Figure 20. Shown is the postoperative inlet pelvis.
Fixation techniques
With reduction clamps in place anteriorly, definitive fixation of the posterior ring is achieved with percutaneous cannulated screw placement. Trans-sacral transiliac (TSTI) screws are preferable but their use may not be possible in cases of dysmorphism or comminuted sacral fracture.
We begin with a perfect lateral sacral radiograph. Visualization of the overlap of the iliocortical densities (ICD) confirms image adequacy. We use a 2.8-mm drill-tip guide wire to accommodate a 6.5-mm or 7.3-mm screw. The wire is centered in the S1 body and an incision is made in this location. The wire is advanced using a lateral view until it is in contact with the ilium distal to the ICD (Figure 9). We then move to an inlet view. It is essential to ensure the inlet angle is the most appropriate based on preoperative planning and shows the densest possible S1 anterior cortex. Wire trajectory is checked and adjusted. We then move to an outlet view and ensure avoidance of the S1 sacral foramina. With the trajectories confirmed on both views, the wire is advanced using regular inlet/outlet views. Use of proprioceptive feedback during wire advancement is critical. If sacral anatomy allows for a TSTI screw, we use an inlet obturator oblique view of the contralateral hemipelvis to ensure accurate length of the wire (Figure 10). The same sequence is repeated in the S2 body, understanding the possible variation of the inlet view of the S2 vertebral body. A lateral fluoroscopic view of the sacrum is important at this point to ensure the entirety of the wire is located within the respective vertebral bodies. Screw lengths are then measured and selected.
Figure 22. Sequential CT scan cuts of the axial posterior pelvis used to confirm successful reduction and safe hardware placement in the S2 segment are shown.
Posterior diastasis usually remains at this point, despite correction of proximal and posterior displacement. We next aim to compress the ilium against the sacrum. One technique is to use a partially threaded screw. However, our experience has demonstrated the superior force of a fully threaded 7.3-mm screw lagged by technique. We over-drill the near segment using a cannulated 7.3-mm drill (Figures 11 and 12) and place a 7.3-mm fully threaded screw with a washer (Figures 13 and 14). We use an ipsilateral inlet obturator oblique view, which shows the washer abutting the ilium, to confirm appropriate contact (Figure 15).
With the posterior ring reduced and fixed, we return to the anterior pelvic fixation. The Jungbluth clamp may be adjusted to obtain a perfect reduction. A six-hole reconstruction pelvic plate is then placed over the superior aspect of the pubic symphysis. For enhanced stability, we attempt to aim the most medial screw laterally toward the ischial tuberosity, to aim the second screw medially and to aim the most lateral screw toward the obturator foramen. The quality of the reduction and fixation are confirmed through an inlet and outlet view (Figures 16 and 17).
Postoperative recommendations
We obtain postoperative radiographs (Figures 18, 19 and 20) and CT (Figures 21 and 22) to verify adequacy of reduction and fixation. The treating surgeon must continue to reassess for possible missed injuries. Our data suggest that up to 8% of cases involve a missed occult contralateral pelvic injury. Patients may be allowed to weight-bear as tolerated depending on any associated injuries.
- References:
- Blum L, et al. Int Orthop. 2018;doi:10.1007/s00264-018-3883-1.
- Maertens AS, et al. Int Orthop. 2018;doi:10.1007/s00264-018-4268-1.
- Martin MP 3rd, et al. Eur J Orthop Surg Traumatol. 2018;doi:10.1007/s00590-017-2104-8.
- For more information:
- Michael H. Maher, MD; Cyril Mauffrey, MD, FACS, FRCS, director of orthopedic trauma in the department of orthopedics at Denver Health Medical Center; and Joshua A. Parry, MD, can be reached at 777 Bannock St., Denver, CO 80204. Maher’s email: michael.h.maher@gmail.com. Mauffrey’s email: mauffreyc@gmail.com. Parry’s email: joshua.alan.parry@gmail.com.
Disclosures: Parry, Maher, and Mauffrey report no relevant financial disclosures.