Clinical application of anterior ring internal fixator system combined with sacroiliac screw fixation in Tile C pelvic fracture treatment

Lower abdominal cyst complicated with suspected infection following INFIX internal fixation for pelvic fracture: a report of two rare cases

BACKGROUND

The Internal Fixator (INFIX) is a popular method, known for its minimal invasiveness and short operation time, for treating anterior pelvic ring fractures. Studies have shown that postoperative complications may occur, including anterolateral femoral cutaneous nerve injury, the femoral nerve paralysis, and delayed fracture healing. These complications are believed to be related to surgical stimulation, an excessively long lateral end of the connecting rod, a small distance between the screw and bone surface, insufficient pre-bending of the connecting rod, and difficulties in fracture reduction.

CASE PRESENTATION

We report two unique cases of lower abdominal pseudocyst complicated with suspected infection after INFIX treatment of pelvic fractures at our trauma center. Following surgical removal of the internal fixation, resolution of the cysts was observed in both patients, and subsequent postoperative follow-up revealed the absence of any residual sequelae. These cases have not been reported in previous literature reviews.

DISCUSSION

The lower abdominal cysts, potentially arising from the dead space created during intraoperative placement of the INFIX rod, may increase infection risk. The etiology remains uncertain, despite the presence of abnormal inflammation markers in both cases, and staphylococcus aureus found in one. These cysts were confined to the lower abdomen, not involving the internal fixation, and hence, only the INFIX was removed. Postoperative oral cefazolin treatment was successful, with resolved pseudocysts and no subsequent discomfort.

CONCLUSION

We report two unprecedented cases of post-INFIX abdominal cysts, with a suspected link to intraoperative dead space. Despite uncertain etiology, successful management involved INFIX removal and oral cefixime therapy. These findings necessitate further exploration into the causes and management of such complications.

Surgical Management of Unstable U-Shaped Sacral Fractures and Tile C Pelvic Ring Disruptions: Institutional Experience in Light of a Narrative Literature Review

Unstable U-shaped sacral fractures and vertical shear Tile C pelvic ring disruptions are characterized by rare lesions occurring in patients with severe trauma. Because the initial damage-control resuscitation primarily aims to stop life-threatening bleeding, emergency treatment often includes an anterior external pelvic fixator. Delayed surgery is mandatory to allow early mobilization, reduce mortality, and improve functional outcomes. Regarding U-shaped sacral fractures, although Roy-Camille type 1 U-shaped sacral fractures can be treated with iliosacral screws, types 2 (posteriorly displaced, equivalent to AO Spine C3) and 3 (anteriorly displaced, equivalent to AO Spine C3) fractures require spinopelvic triangular fixation. Besides, proper reduction of type 2 and some type 3 sacral fractures is mandatory to prevent wound complications. In patients with neurological deficits, the need for sacral laminectomy is left at the discretion of the surgeon, given the indirect decompression already obtained with fracture reduction. Tile C pelvic disruptions with posterior ring injury located lateral to the sacral foramen can be treated with either iliosacral screws or triangular spinopelvic fixation, combined with anterior pelvic fixation. Conversely, Tile C pelvic disruptions with posterior ring injury located at, or medial, to the sacral foramen (Denis zone II or III) induce vertical lumbosacral instability and thus require spinopelvic triangular fixation with anterior pelvic osteosynthesis. Although minimally invasive techniques have been developed, open surgeries are still required for inexperienced operators and in case of major displacement. The complication rate reaches approximately 33.33% of the cases, and complications include hardware malposition, wound infection or dehiscence, hardware prominence, and sometimes hardware failure.

Finite Element Analysis of Channel Screw and Conventional Plate Technique in Tile B2 Pelvic Fracture

Objective: This study aims to analyze the biomechanical characteristics of tile B2 pelvic fractures using finite element analysis when the superior ramus of the pubis was fixed by a plate or hollow screws in standing and sitting positions, respectively. Methods: A three-dimensional digital model of the tile B2 pelvic fracture was obtained by CT scanning the patient. The main ligament structure was then reconstructed based on the anatomical characteristics to create a finite element model of the tile B2 pelvic fracture. The posterior pelvic ring was fixed by sacroiliac joint screws, while the anterior ring injury of the superior ramus of the pubis was fixed by plates and hollow compression screws, respectively. The degrees of freedom of the bilateral acetabulum or two sides of the ischial tuberosity were constrained in the two models. A vertical load of 600 N was applied to the upper surface of the sacrum to measure the displacement and stress distribution of the pelvis in the standing and sitting positions. Results: The displacement distribution of both the healthy and the affected side of the pelvis was relatively uniform in both the plate group and the hollow screw group according to the finite element simulation results. The maximum displacement value in the sitting position was greater than the standing position, and the maximum displacement value of the hollow screw fixation was greater than that of the plate fixation. In the four groups of fixation models, the maximum displacement value of the pelvis in the hollow screw sitting position group was 1616.80 × 10−3 mm, which was greater than that of the other three groups, and in this group the total displacement value of the hollow screw in the anterior ring was 556.31 × 10−3 mm. The stress distribution of the pelvis in the various models was similar in the four groups of models, in which the maximum stress of the pelvis in the hollow screw sitting position group was the largest, which was 201.33 MPa, while the maximum stress in the standing position was 149.85 MPa greater than that in the sitting position of the hollow screw fixation. Conclusion: The anterior ring of patients with Tile B2 pelvic fractures fixed with hollow screws or plates in both standing and sitting positions can achieve satisfactory biomechanical results with significant safety margins for plates and screws.

Modified percutaneous iliosacral screw and anterior internal fixator technique for treating unstable pelvic fractures: a retrospective study

BACKGROUND

The commonly used technique for treating unstable pelvic fractures with sacroiliac screws and anterior internal fixator (INFIX) is prone to complications, such as injury to the pelvic vasculature and nerves, life-threatening bleeding, lateral femoral cutaneous neuritis, and wound infection. This study investigated the clinical effects of using a modified percutaneous iliosacral screw and INFIX technique for treating unstable pelvic fractures.

METHODS

A retrospective analysis of minimally invasive internal fixation using modified incision of an anterior-ring INFIX application combined with modified percutaneous iliosacral screw placement was performed for 22 cases of unstable pelvic fractures from January 2017 to December 2018. Based on the Tile classification, there were 4 type B1, 7 type B2, 5 type B3 and 6 type C1 injuries. Preoperatively, the length and orientation of the internal fixation were computer-simulated and measured. On postoperative day 3, pelvic radiographs and three-dimensional computed tomograms were used to assess fracture reduction and fixation. All patients were regularly followed up at 4 weeks, 12 weeks, 6 months, 12 months, 24 months and annually thereafter. Fracture healing, complications, visual analogue scale (VAS) scores, the quality of fracture repositioning and Majeed score were assessed during follow-up.

RESULTS

All patients were followed up for a mean of 25.23 ± 1.48 months. All fractures healed without loss of reduction and no patient showed evidence of delayed union or nonunion. Two years postoperatively, the mean VAS score was 0.32 ± 0.09 and the mean Majeed score was 94.32 ± 1.86.

CONCLUSION

The modified percutaneous iliosacral screw technique increases the anterior tilt of the sacroiliac screw by shifting the entry point posteriorly to increase the safety of the screw placement. Downward modification of the INFIX incision reduces the risk of lateral femoral cutaneous nerve injury. This technique is safe, effective and well tolerated by patients.