Risks to the Superior Gluteal Neurovascular Bundle During Iliosacral and Transsacral Screw Fixation: A Computed Tomogram Arteriography Study

New Minimally Invasive Method for Treating Posterior Pelvic Ring Fractures: Biomechanical Validation and Clinical Application of Sacroiliac Joint Locking Plate

OBJECTIVE

Considering the high incidence and complexity of unstable posterior pelvic ring fractures, and the need for less invasive and more effective treatment options, this study aims to introduce a novel minimally invasive, safe, and simple internal fixation method for the treatment of unstable posterior pelvic ring fractures using the sacroiliac joint locking plate (SJP) system, and to provide biomechanical validation and clinical evaluation of this method.

METHODS

Biomechanical research was conducted using standard pelvic bone models from Synbone, Switzerland, to create Denis II zone unstable posterior pelvic ring fracture models, and to assess the stability of the SJP under different loads compared with traditional fixation methods. A retrospective clinical study analyzed the clinical efficacy of SJP treatment in 62 patients (mean age of 51.7 ± 11.9 years and male-to-female ratio of 42/20) treated at our hospital from October 2016 to January 2023.

RESULTS

Biomechanical tests showed that at a maximum load of 300 N, the displacement values for the SJP (3.361 ± 0.246 mm) and two iliosacral (IS) screws (3.325 ± 0.335 mm) were significantly lower than those for a single IS screw (4.281 ± 0.399 mm) and tension band plate (TBP) (4.678 ± 0.534 mm). In the stiffness test of the compression-separation experiment, the average stiffness of the SJP (92.09 ± 1.17 N/mm) was higher than that of a single IS screw (80.06 ± 2.57 N/mm) and TBP (71.67 ± 1.12 N/mm) (p < 0.05 for both), but lower than that of two IS screws (104.94 ± 1.16 N/mm) (p < 0.05). Clinically, postoperative pain scores decreased to 1.9 ± 0.9 after SJP surgery, which was a significant reduction compared with the preoperative score of 9.1 ± 1.1. Functional prognosis scores improved from 36.1 ± 11.5 preoperatively to 88.4 ± 14.2, showing a marked improvement. The postoperative Majeed scores for the patients were 87.4 ± 8.1, and the incidence of complications was low, with only one case reported so far.

CONCLUSION

The SJP demonstrates robust stability in biomechanical experiments, making it highly advantageous for clinical applications and widespread adoption. It offers several benefits, including straightforward surgical operation, minimal risk of vascular and neural injury, low surgical requirements, and eliminates the need for fluoroscopy. These advantages contribute to its remarkable clinical efficacy and potential for extensive utilization.

Surgical complications after fixation of minimally displaced lateral compression type 1 pelvic ring injuries

PURPOSE

To review surgical complications after fixation of stress-positive minimally displaced (< 1 cm) lateral compression type 1 (LC1) pelvic ring injuries.

METHODS

A retrospective study at a level one trauma center identified patients who received surgical fixation of isolated LC1 pelvic ring injuries. Surgical complications and additional procedures were reviewed.

RESULTS

Sixty patients were included. The median age was 61 years (Interquartile range 40-70), 65% (n = 39) were women, and 57% (n = 34) had high-energy mechanisms. Anterior-posterior, posterior-only, and anterior-only fixation constructs were used in 77% (n = 46), 15% (n = 9), and 8% (n = 5) of patients. Anterior fixation was performed with rami screw fixation in 82% (49/60), external fixation in 2% (1/60), and open reduction and plate fixation in 2% (1/60). There were 15 surgical complications in 23% (14/60), and 12 additional procedures in 17% (10/60). Complications included loss of reduction ≥ 1 cm (8%), symptomatic hematomas (8%), symptomatic backout of unicortical retrograde rami screws (5%), deep infection of the pelvic space after a retrograde rami screw (1.6%), and iatrogenic L5 nerve injury (1.6%). All losses of reduction involved geriatric females with distal rami fractures sustained in ground-level falls. Loss of reduction was found to be more likely in patients with low energy mechanisms (proportional difference (PD) 62%, 95% confidence interval (CI) 18% to 76%; p = 0.01) and 2 versus 1 posterior pelvic screws (PD 36%; CI 0.4% to 75%; p = 0.03).

CONCLUSIONS

Surgical complications and additional procedures routinely occurred after fixation of LC1 injuries. Patients should be appropriately counseled on the risks of surgical fixation of these controversial injuries.

LEVEL OF EVIDENCE

Diagnostic, Level III.

Safety and Preliminary Effectiveness of Lateral Transiliac Sacroiliac Joint Fusion by Interventional Pain Physicians: A Retrospective Analysis

Introduction

Minimally invasive sacroiliac (SI) joint fusion has become the mainstay treatment for chronic refractory sacroiliac joint dysfunction. Multiple procedures are now available including transfixing procedures with implants placed in the lateral or posterolateral transiliac trajectories, and intra-articular procedures with devices and/or allograft placed via a dorsal approach. To date, the published literature on the lateral approach has been primarily by surgeons. This retrospective chart review aims to evaluate the safety and preliminary effectiveness when the procedure is performed by physicians trained in interventional pain management.

Methods

Retrospective analysis of patients who underwent lateral SI joint fusion using a lateral transiliac approach between December 2022 and September 2023 by a single physician. Data on demographics, perioperative details, complications, and postoperative outcomes were collected and analyzed. The study was reviewed by WCG IRB and received an exemption authorization.

Results

Medical charts were reviewed for the first 49 consecutive cases performed. Mean (SD, range) age was 64 (11, 34-83), BMI was 32.5 (8.4), 59% were female, 35% were smokers, and 82% were on opioids at baseline. Mean (SD) operative time was 40 (11) minutes and all procedures were performed at an ambulatory surgery center under monitored anesthesia care. No device- or procedure-related complications occurred. Mean follow up was 175 days; Mean (SD) baseline reported pain was 9 (1.5) on a 0-10 numerical rating scale. At follow up, 88% of the patients reported ≥50% pain relief. Six patients who reported 0% relief suffer from multiple pain generators and are on long term opioids.

Conclusion

Results of this single center experience support the safety of lateral SI joint fusion using a threaded implant when performed by interventional pain management physicians. However, further prospective studies with larger sample sizes and longer follow-ups are warranted to validate these findings.

Incidence of Suboptimal Fluoroscopic Outlet Imaging of the Sacrum and Pelvic Retroversion Necessary for Optimal Views

OBJECTIVES

To estimate the prevalence of suboptimal fluoroscopy of sacral outlet images due to anatomic and equipment dimensions. Pelvic retroversion is hypothesized to mitigate this issue.

METHODS

DESIGN

In silico simulations using retrospectively collected computed tomography (CT) data from human patients.

SETTING

Level I trauma center.

PATIENT SELECTION CRITERIA

Adults with OTA/AO 61 pelvic ring disruptions treated with posterior pelvic fixation between July and December 2021.

OUTCOME MEASURES AND COMPARISONS

C-arm tilt angles required to obtain 3 optimal fluoroscopic sacral outlet images, defined as vectors from pubic symphysis to S2 and parallel to the first and second sacral neural foramina, were calculated from sagittal CT images. A suboptimal view was defined as collision of the C-arm radiation source or image intensifier with the patient/operating table at the required tilt angle simulated using the dimensions of 5 commercial C-arm models and trigonometric calculations. Incidence of suboptimal outlet views and pelvic retroversion necessary to obtain optimal views without collision, which may be obtained by placement of a sacral bump, was determined for each view for all patients and C-arm models.

RESULTS

CT data from 72 adults were used. Collision between patient and C-arm would occur at the optimal tilt angle for 17% of simulations and at least 1 view in 68% of patients. Greater body mass index was associated with greater odds of suboptimal imaging (standard outlet: odds ratio [OR] 0.84, confidence interval [CI] 0.79-0.89, P < 0.001; S1: OR 0.91, CI 0.87-0.97, P = 0.002; S2: OR 0.85, CI 0.80-0.91, P < 0.001). S1 anterior sacral slope was associated with suboptimal S1 outlet views (OR 1.12, Cl 1.07-1.17, P < 0.001). S2 anterior sacral slope was associated with suboptimal standard outlet (OR 1.07, Cl 1.02-1.13, P = 0.004) and S2 outlet (OR 1.16, Cl 1.09-1.23, P < 0.001) views. Retroversion of the pelvis 15-20 degrees made optimal outlet views possible without collision in 95%-99% of all simulations, respectively.

CONCLUSIONS

Suboptimal outlet imaging of the sacrum is associated with greater body mass index and sacral slope at S1 and S2. Retroversion of the pelvis by 15-20 degrees with a bump under the distal sacrum may offer a low-tech solution to ensure optimal fluoroscopic imaging for percutaneous fixation of the posterior pelvic ring.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Numerical study of pedicle screw construction and locking compression plate fixation in posterior pelvic ring injuries: Analyzed by finite element method

BACKGROUND

The aim of this study was to compare the biomechanical performance of pedicle screw construction and locking compression plate fixation in posterior pelvic ring injuries analyzed by finite element method.

METHODS

A 3-dimensional finite element model of the spine-pelvis-femur complex with ligaments was reconstructed from computed tomography images. An unstable posterior pelvic ring injury was created, which was fixed with a pedicle screw construction or locking compression plate. A follower load of 400 N was applied to the upper surface of the vertebrae to simulate the upper body weight, while the ends of the proximal femurs were fixed. The construct stiffness, the maximum vertical displacement, the maximum posterior displacement, the maximum right displacement, and the overall maximum displacement of the sacrum, and stress distributions of the implants and pelvises were assessed.

RESULTS

The construct stiffness of the pedicle screw model (435.14 N/mm) was 2 times that of the plate model (217.01 N/mm). The maximum vertical displacement, the maximum posterior displacement, the maximum right displacement, and the overall maximum displacement of the sacrum in the pedicle screw model were smaller than those in the plate model (0.919, 1.299, 0.259, and 1.413 mm in the pedicle screw model, and 1.843, 2.300, 1.053, and 2.895 mm in the plate model, respectively). The peak stresses of the implant and pelvis in the pedicle screw model decreased by 80.4% and 25% when compared with the plate model (44.57 and 34.48 MPa in the pedicle screw model, and 227.47 and 45.97 MPa in the plate model, respectively).

CONCLUSION

The study suggested that the pedicle screw construction could provide better fixation stability than the locking compression plate and serves as the recommended fixation method for the treatment of posterior pelvic ring injuries.

Bilateral dual iliac screw pelvic fixation for adult spinal deformity: a case report of a superior gluteal artery pseudoaneurysm secondary to aberrant iliac screw trajectory

PURPOSE

To present a case of a pseudoaneurysm of a branch of the left superior gluteal artery (SGA) secondary to lateral wall perforation from an iliac screw and its subsequent evaluation and management.

METHODS

Case report.

RESULTS

A 67-year-old female with a history of degenerative flatback and scoliosis and pathological fractures of T12 and L1 secondary to osteodisciitis underwent a single0stage L5-S1 ALIF and T9-pelvis posterior instrumented fusion with bilateral dual iliac screw fixation, revision T11-S1 decompression, and T12 and L1 irrigation and debridement and partial corpectomies. During the operation, non-pulsatile bleeding was encountered after creating an initial trajectory for the more proximal of the two left iliac screws. While the initial post-operative course was benign, the patient was readmitted for hypotension and anemia. Computed tomography of the abdomen/pelvis demonstrated a pseudoaneurysm (2.3 cm × 2.1 cm × 2.3 cm) of a branch of the left SGA. Diagnostic angiogram confirmed a pseudoaneurysm off of one of the branches of the left SGA. Endovascular embolization using multiple coils resulted in a complete cessation of blood flow in the pseudoaneurysm. At 2 years follow-up, no symptoms suggestive of recurrence of the pseudoaneurysm were reported.

CONCLUSIONS

A pseudoaneurysm of a branch of the left superior gluteal artery as a result of lateral wall perforation from an aberrantly placed iliac screw during an adult spinal deformity operation involving dual screw pelvic fixation is reported. Prompt recognition, multidisciplinary collaboration, and appropriate intervention were key in achieving a successful outcome and preventing further morbidity.

Differences in Accuracy and Radiation Dose in Placement of Iliosacral Screws: Comparison between 3D and 2D Fluoroscopy

Percutaneous iliosacral screw fixation is a widely accepted method of stabilizing the posterior pelvic ring. Recently developed tools such as 3D-navigated fluoroscopy and computed navigation seem to prevent a surgeon from conducting screw misplacement. The study aimed to comparatively assess the introduction of sacroiliac screw placement using 2D and 3D fluoroscopy in terms of accuracy and radiation exposure. Iliosacral screws were introduced in 37 patients using 2D (group N1) and in 36 patients using 3D fluoroscopy (group N2) techniques. Overall, 61 and 56 screws were introduced in groups N1 and N2, respectively. Screw placement accuracy was assessed using postoperative computed tomography and Smith’s scale. Intraoperative radiation exposure was also assessed. No differences were noted between groups in terms of screw positioning accuracy and radiation dose. Both 2D and 3D fluoroscopy provide good visualization for safely placing percutaneous iliosacral joint screws. Using 3D fluoroscopy-based navigation in comparison with 2D fluoroscopy is not advantageous.

Superior gluteal artery injury risk from third sacral segment transsacral screw insertion

OBJECTIVES

Iliosacral (IS) and transsacral (TS) screws are commonly used to stabilize pelvic ring injuries. The course of the superior gluteal artery (SGA) can be close to implant insertion paths. The third sacral segment (S3) has been described as a viable osseous fixation pathway (OFP) but the proximity of the SGA to the S3 screw path is unknown.

METHODS

Fifty uninjured patients with contrasted pelvic computed tomograms (CTA) were identified with an S3 path large enough for a 7.0 mm TS screw. Starting sites for S1 IS or TS, S2 and S3 TS screws were located on the volume rendered lateral CTA image and transferred onto the surface rendered 3D CTA with the SGA clearly visible. The distance from screw start sites to the SGA was measured. A distance less than 3.5 mm was considered likely for injury.

RESULTS

The average distances from screw start sites to the SGA were 23.0 ± 7.9 mm for S1 IS screws, 14.3 ± 6.4 mm for S2 TS screws and 25.9 ± 6.5 mm for S3 TS screws. No S1 IS screws, 5 S2 TS screws (10%), and no S3 TS screws were projected to cause injury to the SGA.

CONCLUSIONS

The osseous start site and soft tissue path for an S3 TS screw is remote from the SGA. The S1 IS and S3 TS pathways are further away from the SGA while the S2 TS pathway is closer and may theoretically pose a higher injury risk in patients with an available S3 OFP.

Pelvic antropometric measurement in 3D CT for placement of two unilateral iliosacral S1 - 7.3 mm screws

PURPOSE

Stability of the dorsal pelvic ring is important for patient mobilisation and can be restored using several surgical procedures after fracture. Placement of percutaneous iliosacral screws is a reliable and minimal-invasive technique to achieve stabilisation of the dorsal pelvic ring by placement of two screws in the first sacral vertebra. Aim of this study was to evaluate 3D CT scans regarding the anatomical possibility to place two 7.3 mm iliosacral screws for fixation of the dorsal pelvic ring.

METHODS

3D CT datasets of 500 consecutive trauma patients with 1000 hemipelves of a mid-european level I trauma centre with or without pelvic injury were evaluated and measured bilaterally in this retrospective study.

RESULTS

One thousand hemipelvic datasets of 500 patients (157 females, 343 males) with a mean age of 49.7 years (18 to 95) were included in this study. Only 16 hemipelves (1.6%, 11 in females, 5 in males) in 14 patients (2.8%, 9 females = 5.73%, 5 males = 1.5%) showed too narrow corridors so that 7.3 mm screw placement would not be possible (p = 0.001). In women, too narrow corridors occurred 3.9 times as often as in men. Only two females showed this bilaterally.

CONCLUSION

The evaluation of 3D CT scans of the pelvis showed the importance of planning iliosacral screw placement, especially if two 7.3 mm screws are intended to be placed in the first sacral vertebra.

Delayed lower extremity paresis following iliosacral screws: Atypical complication and treatment

Percutaneous iliosacral screw placement has become the technique of choice for treating injuries to the posterior pelvis. However, the technique requires an understanding of the anatomy surrounding the bone corridors to avoid complications and detect them early if they occur. We present the clinical case of a patient with a U-shaped fracture of the sacrum that evolves with gluteal pain and left foot equine paresis after percutaneous fixation with iliosacral screws. Angio-CT of the pelvis shows active arterial bleeding from the superior gluteal artery associated to extensive hematoma in the thickness of the gluteus medius muscle. Emergency embolization is performed by installing coil and gelatin. Successful control of bleeding is achieved. To avoid this complication, a complete imaging study is recommended in planning the surgery and to avoid multiple repositioning of the guide or screw. Arterial injury should be suspected in case of increasing pain despite analgesia, functional impairment or neurological deficit and the angiographic study and resolution by selective embolization of the bleeding vessels must be performed.

Vertical shear pelvic ring injuries: do transsacral screws prevent fixation failure?

OBJECTIVES

To determine the frequency of fixation failure after transsacral-transiliac (TS) screw fixation of vertical shear (VS) pelvic ring injuries (OTA/AO 61C1) and to describe the mechanism of failure of TS screws.

DESIGN

Retrospective cohort study.

SETTING

Level 1 academic trauma center.

PATIENTS/PARTICIPANTS

Twenty skeletally mature patients with unilateral, displaced, unequivocal VS injuries were identified between May 1, 2009 and April 31, 2016. Mean age was 31 years and mean follow-up was 14 months. Twelve had sacroiliac dislocations (61C1.2) and eight had vertical sacral fractures (61C1.3).

INTERVENTION

Operative treatment with at least one TS screw.

MAIN OUTCOME MEASUREMENTS

Radiographic failure, defined as a change of >1 cm of combined displacement of the posterior pelvis compared with the intraoperative position on inlet and outlet radiographs.

RESULTS

Radiographic failure occurred in 4 of 8 (50%) vertical sacral fractures. Posterior fixation was comprised of a single TS screw in 3 of these 4 failures. The dominant mechanism of screw failure was bending. All of these failures occurred early in the postoperative period. No fixation failures occurred among the sacroiliac dislocations. There were no deep infections or nonunions.

CONCLUSIONS

This is the first study to describe the mechanism of failure of TS screws in a clinical setting after VS pelvic injuries. We caution surgeons from relying on single TS screw fixation for vertically unstable sacral fractures. Close radiographic monitoring in the first few weeks after surgery is advised.

LEVEL OF EVIDENCE

Level IV.

Biomechanical Comparison of Three Internal Fixation Techniques for Stabilizing Posterior Pelvic Ring Disruption: A 3D Finite Element Analysis

OBJECTIVE

To compare the biomechanical stability and compatibility of two iliosacral screws (ISS), a tension band plate (TBP), and a minimally invasive adjustable plate (MIAP) for treating Tile C pelvic fractures.

METHODS

Three groups of finite element models of the intact pelvis, including the main ligament and the proximal one-third of both femurs, were developed to simulate vertical sacral fractures and treated with the three abovementioned internal fixation techniques. A 500 N vertical load, a 500 N vertical load plus a 10 Nm moment of forward sagittal direction, and 500 N vertical load plus a 10 Nm moment of right lateral direction were applied to the sacrum to simulate standing status, bending status, and flexion status, respectively. The maximum displacement value, the stress value, and the stress value of the fracture interface were compared among the three internal fixation techniques.

RESULTS

The results showed that all three internal fixation techniques effectively restored the biomechanical transmission of the injured pelvis. The stress on the implants in the TBP model was 167.47% and 53.41% higher than that in the ISS model and the MIAP model, respectively, and the stress shielding phenomenon of the TBP model was more obvious than in the other two models. Meanwhile, the stress between the fracture interfaces in the TBP fixation models was apparently higher than that in the other two models. However, the vertical displacement of the MIAP model was not significantly different from that in the ISS and TBP model; therefore, strong fixation could be obtained in all three models.

CONCLUSION

Based on our results, we believe that the stability of Tile C pelvic fracture fixed with MIAP was similar to that of fractures fixed with ISS and TBP, but the stress shielding phenomenon and safety of implants in the TBP models were inferior to those in the MIAP and ISS fixation models. Meanwhile, MIAP and ISS fixation were more helpful to the healing processing than was TBP fixation, especially at the fracture interface of the second and third vertebral body levels.