The biomechanical effect of lumbopelvic distance reduction on reconstruction after total sacrectomy: a comparative finite element analysis of four techniques

BACKGROUND CONTEXT

Following total sacrectomy, lumbopelvic reconstruction is essential to restore continuity between the lumbar spine and pelvis. However, to achieve long-term clinical stability, bony fusion between the lumbar spine and the pelvic ring is crucial. Reduction of the lumbopelvic distance can promote successful bony fusion. Although many lumbopelvic reconstruction techniques (LPRTs) have been previously analyzed, the biomechanical effect of lumbopelvic distance reduction (LPDR) has not been investigated yet.

PURPOSE

To evaluate and compare the biomechanical characteristics of four different LPRTs while considering the effect of LPDR.

STUDY DESIGN/SETTING

A comparative finite element (FE) study.

METHODS

The FE models following total sacrectomy were developed to analyze four different LPRTs, with and without LPDR. The closed-loop reconstruction (CLR), the sacral-rod reconstruction (SRR), the four-rod reconstruction (FRR), and the improved compound reconstruction (ICR) techniques were analyzed in flexion, extension, lateral bending, and axial rotation. Lumbopelvic stability was assessed through the shift-down displacement and the relative sagittal rotation of L5, while implant safety was evaluated based on the stress state at the bone-implant interface and within the rods.

RESULTS

Regardless of LPDR, both the shift-down displacement and relative sagittal rotation of L5 consistently ranked the LPRTs as ICR

CONCLUSIONS

LPDR significantly improved both lumbopelvic stability and implant safety in all reconstruction techniques after total sacrectomy. LPDR reduced the shift-down displacement of L5, the relative sagittal rotation of L5, and the stress values at the bone-implant interface. Furthermore, in the ICR and SRR techniques, LPDR decreased the peak stress values within the rods. All four investigated LPRTs demonstrated suitability for lumbopelvic reconstruction, with the ICR technique exhibiting the highest lumbopelvic stiffness.

CLINICAL SIGNIFICANCE

LPDR creates a biomechanically advantageous environment following total sacrectomy; therefore, it has the potential to impact the design of custom-made 3D-printed or traditional LPRTs. However, to confirm the findings of the current FE study, long-term clinical trials are recommended.

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Key Words

• Biomechanics
• Finite element analysis
• Lumbopelvic distance reduction
• Lumbopelvic fixation
• Lumbopelvic reconstruction
• Lumbopelvic stabilization
• Total sacrectomy

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Affiliation(s)

Mate Turbucz School of PhD Studies, Semmelweis University, Budapest, Hungary; In Silico Biomechanics Laboratory, National Center for Spinal Disorders, Buda Health Center, Budapest, Hungary.
Agoston Jakab Pokorni School of PhD Studies, Semmelweis University, Budapest, Hungary; In Silico Biomechanics Laboratory, National Center for Spinal Disorders, Buda Health Center, Budapest, Hungary.
Benjamin Hajnal School of PhD Studies, Semmelweis University, Budapest, Hungary; In Silico Biomechanics Laboratory, National Center for Spinal Disorders, Buda Health Center, Budapest, Hungary.
Kristof Koch School of PhD Studies, Semmelweis University, Budapest, Hungary; National Center for Spinal Disorders, Buda Health Center, Budapest, Hungary.
Zsolt Szoverfi National Center for Spinal Disorders, Buda Health Center, Budapest, Hungary.
Peter Pal Varga National Center for Spinal Disorders, Buda Health Center, Budapest, Hungary.
Aron Lazary National Center for Spinal Disorders, Buda Health Center, Budapest, Hungary; Department of Spine Surgery, Department of Orthopaedics, Semmelweis University, Budapest, Hungary.
Peter Endre Eltes In Silico Biomechanics Laboratory, National Center for Spinal Disorders, Buda Health Center, Budapest, Hungary; National Center for Spinal Disorders, Buda Health Center, Budapest, Hungary; Department of Spine Surgery, Department of Orthopaedics, Semmelweis University, Budapest, Hungary.

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Lumbopelvic fixation in the treatment of spinopelvic dissociation: union, complications, and neurologic outcomes of a multicenter case series

PURPOSE

To review outcomes of spinopelvic dissociation treated with open lumbopelvic fixation.

METHODS

We reviewed all cases of spinopelvic dissociation treated at three Level-I trauma centers with open lumbopelvic fixation, including those with adjunctive percutaneous fixation. We collected demographic data, associated injuries, pre- and postoperative neurologic status, pre- and postoperative kyphosis, and Roy-Camille classification. Outcomes included presence of union, reoperation rates, and complications involving hardware or wound.

RESULTS

From an initial cohort of 260 patients with spinopelvic dissociation, forty patients fulfilled inclusion criteria with a median follow-up of 351 days. Ten patients (25%) had a combination of percutaneous iliosacral and open lumbopelvic repair. Average pre- and postoperative kyphosis was 30 degrees and 26 degrees, respectively. Twenty patients (50%) had neurologic deficit preoperatively, and eight (20%) were unknown or unable to be assessed. All patients presenting with bowel or bladder dysfunction (n = 12) underwent laminectomy at time of surgery, with 3 patients (25%) having continued dysfunction at final follow-up. Surgical site infection occurred in four cases (10%) and wound complications in two (5%). All cases (100%) went on to union and five patients (13%) required hardware removal.

CONCLUSION

Open lumbopelvic fixation resulted in a high union rate in the treatment of spinopelvic dissociation. Approximately 1 in 6 patients had a wound complication, the majority of which were surgical site infections. Bowel and bladder dysfunction at presentation were common with the majority of cases resolving by final follow-up when spinopelvic dissociation had been treated with decompression and stable fixation.

Posterior pelvic ring injuries, lumbosacral junction instabilities and stabilization techniques for spinopelvic dissociation: a narrative review

INTRODUCTION

From transiliac Harrington rods to minimally invasive (MIS) percutaneous 3D-navigated transsacral-transiliac screw (TTS) fixation, concepts of fixation methods in pelvic injuries with spinopelvic dissociation (SPD) are steadily redefined. This narrative review examines the literature of recent years regarding surgical treatment options and trends in SPD, outlining risks and benefits of each treatment option and addressing biomechanical aspects of sacral injuries and common classification systems.

MATERIALS AND METHODS

A literature search on the search across relevant online databases was conducted. As a scale for quality assessment, the SANRA-scoring system was taken into account.

RESULTS

Sacral Isler type 1 injuries of the LPJ in U- and H-type fractures are frequently treated with stand-alone TTS. Fractures with higher instability (Isler types 2 and 3) require unilateral or bilateral LPF, subject to side involvement, as a buttressing construct, or triangular fixation as additional compression and neutralization, determined by fracture radiation. A more comprehensive classification from which to derive stabilization options is provided by the 2023 301SPD classification. MIS techniques are on the rise and offer shorter OR time, less blood loss, fewer infections, and fewer wound complications. It is advisable to implement MIS techniques as much as possible, as long as decompression is not required and closed fracture reduction succeeds satisfactorily.

CONCLUSION

SPD is characteristic of severe injuries, mostly in polytraumatized patients. The complication rates are decreasing due to the increasing adaptation of MIS techniques.

Obturator inlet and iliac oblique technique for safe, convenient, and reliable iliac screw placement

Background

There are many described techniques for the placement of posterior iliac screws for extension of lumbar posterior spinal instrumentation to the pelvis. However, each one has its limitations. We describe our technique for fluoroscopic guidance of iliac screw placement utilizing the obturator inlet and iliac oblique views as well as a detailed review of how to obtain and interpret these views for safe iliac screw placement.

Methods

Retrospective chart review of patients undergoing iliac screw placement utilizing the obturator inlet and iliac oblique views as part of spine instrumentation between January 2019 and March 2022. Screw length and bony breaches are reported utilizing this technique.

Results

Twelve patients underwent posterior lumbopelvic fixation with a total of 23 screws placed via either open or percutaneous technique. The mean screw length was 96.5 mm (Range 80-110, standard dev 7.75). There were no recorded breaches or recannulation attempts.

Conclusions

We show how this technique is a much more convenient alternative to the placement of iliac screws under the obturator outlet oblique ("teardrop" view) which necessitates that the C-arm is in line with the instruments being placed. These described views can be used to place screws with either open or percutaneous techniques and with either the posterior superior iliac spine (PSIS) or S2 alar iliac (S2AI) starting points.

Connecting the S2 alar-iliac screw head to the satellite rod for surgical correction of degenerative sagittal imbalance

PURPOSE

The S2AI screw technique has several advantages over the conventional iliac screw fixation technique. However, connecting the S2AI screw head to the main rod is difficult due to its medial entry point. We introduce a new technique for connecting the S2AI screw head to a satellite rod and compare it with the conventional method of connecting the S2AI screw to the main rod.

METHODS

Seventy-four patients who underwent S2AI fixation for degenerative sagittal imbalance and were followed up for ≥ 2 years were included. All the patients underwent long fusion from T9 or T10 to the pelvis. The S2AI screw head was connected to the satellite rod (SS group) in 43 patients and the main rod (SM group) in 31 patients. In the SS group, the satellite rod was placed medial to the main rod and connected by the S2AI screw and domino connectors. In the SM group, the main rod was connected directly to the S2AI screw head and supported by accessory rods. Radiographic and clinical outcomes were evaluated in both groups.

RESULTS

There were no significant differences in postoperative complications, including proximal junctional failure, proximal junctional kyphosis, rod breakage, screw loosening, wound problems, and infection between the two groups. Furthermore, the correction power of sagittal deformity and clinical results in the SS group were comparable to those in the SM group.

CONCLUSION

Connecting the S2AI screw to the satellite rod is a convenient method comparable to the conventional S2AI connection method in terms of radiological and clinical outcomes.

Percutaneous sacral screw fixation alone sufficient for mildly displaced U-type sacral fractures with preserved osseous fixation pathways

PURPOSE

To describe U-type sacral fracture characteristics amenable to percutaneous sacral screw fixation.

METHODS

U-type sacral fractures were identified from a trauma registry at a level 1 trauma center from 2014 to 2020. Patient demographics, injury mechanism, fracture characteristics, and fixation construct were retrospectively retrieved. Associations between fracture pattern and surgical fixation were identified.

RESULTS

82 U-type sacral fractures were reviewed. Six treated with lumbopelvic fixation (LPF) and 76 were treated with percutaneous sacral screws (PSS) alone. Patients receiving LBF had greater sacral fracture displacement in coronal, sagittal, and axial planes compared to patients receiving PSS alone (P < 0.05), negating osseous fixation pathways. All patients went onto sacral union and there were no implant failures or unplanned reoperations for either group.

CONCLUSION

If osseous fixation pathways are present, U-type sacral fractures can be successfully treated with percutaneous sacral screws. LPF may be indicated in more displaced fractures with loss of spinopelvic alignment. Both techniques for U-type sacral fractures result in reliable fixation and healing without reoperations.

Lumbopelvic Fixation with Bridged Distal Iliac Screws for Vertically Unstable Sacral Fractures

Purpose

The purpose of this study is to evaluate preliminary outcomes of vertically unstable sacral fractures treated by lumbopelvic fixation (LPF) augmented transiliac bridged screws.

Methods

From April 2017 to December 2019, fifteen consecutive patients with vertically unstable sacral fractures who had undergone LPF augmented transiliac bridged screws were enrolled. The radiological assessment included standard lumbopelvic x-rays and pelvic computed tomography (CT) to evaluate the lumbosacral angle (LSA), sacral kyphosis angle (SKA), lumbar lordosis angles (LLA) and Matta's reduction criterias (MRC). Clinical and neurologic impairment outcomes were evaluated by the Majeed grading scale (MGS) and Gibbons criterias, respectively.

Results

All patients were followed for an average of 18 months (range, 14-25). All sacral fractures eventually healed and implant failure did not occur in any patient, though there were two patients with a loss of reduction (< 5 mm) during the follow-up period. According to the MRC, the results were excellent on 14 sides, good on five sides, and fair on one side. The MGS mean score was 82 points (range, 49-98 points); the results were excellent in nine cases, good in four cases, and fair in two cases. There was no statistically significant difference in SKA and LLA in preoperative and postoperative final controls. The preoperative and postoperative LSA were 72 ± 13.9 and 44.1 ± 11.3, respectively, and a statistically significant improvement was observed (p = 0.01).

Conclusion

In vertically unstable sacrum fractures, we believe that LPF augmented with transiliac bridging technique may expedite the reduction of vertical sacrum fracture and offers a reinforced fixation choice.

Set-screw loosening of spinopelvic crab-shaped fixation for a patient with vertically unstable pelvic ring fracture

Spinopelvic fixation (SPF) is an effective treatment method for vertically unstable pelvic ring fractures with spinopelvic dissociations (Patel et al., 2022). A heavy container fell on a 35-year-old man who was trapped and sustained injuries. His pelvic ring fracture dislocation was identified as AO Classification 61-C2.3 with rotational and vertical unstable pelvic ring; thus, crab-shaped fixation (SPF modification) was performed (Okuda et al., 2019). The pelvic fracture was fused, and the clinical outcome was good with modified Majeed score of 96. However, set-screw loosening was observed during the postoperative course. Reports of implant failures in SPF for unstable pelvic ring fractures commonly occur. However, only a few reports have demonstrated implant failure of crab-shaped fixation. Written informed consent was obtained from the patient for publication of this case report and accompanying images.

Lumbopelvic fixation with S2 alar-iliac screws for U-shaped sacral fractures

OBJECTIVE

To investigate the surgical methods and clinical effects of lumbopelvic fixation (LPF) with S2 alar-iliac (S2AI) screws for U-shaped sacral fractures.

METHODS

From December 2019 to August 2020, 14 patients with U-shaped sacral fractures were treated with LPF using S2AI screws. Demographics, fracture classification, mechanism of injury, surgical treatment, complications and clinical results were assessed. All patients had a LPF with or without nerve decompression. The reduction quality was evaluated according to the Matta criteria. Neurological function was evaluated according to the Gibbons grading. The activities of daily life were evaluated according to the Majeed scoring system at the last follow-up.

RESULTS

Among 14 consecutive patients with U-shaped sacral fractures, the age at injury ranged from 13 to 72 years (average 30.3 ± 17.5 years). There were 4 males and 10 females. All patients were followed up for 6-15 months (average 7.8 ± 2.7 months). Thirteen patients were fixed with bilateral S2AI screws, and one patient was fixed only unilaterally due to unilateral spinopelvic dissociation. The excellent and good rate of postoperative pelvic reduction quality was 92% (excellent 10, good 3, fair 1). At the latest follow-up, the excellent and good rate of pelvic function was 100% (excellent 9, good 5) and all patients achieved different extents of neurological recovery. One patient had a postoperative superficial surgical site infection, which healed after debridement. Radiological examination at 3-6 months after operation showed that all fractures had healed. No complications were found in any patients during follow-up, such as implant fracture, loss of reduction, deep wound infection, wound dehiscence and screw protrusion discomfort.

CONCLUSION

LPF with S2AI screws for the treatment of U-shaped sacral fractures has exhibited distinct advantages, including firm fixation, a low rate of surgical site complications and satisfactory clinical efficacy. This approach provides sufficient stability to accelerate the commencement of postoperative rehabilitation.

Comparison of lumbopelvic fixation and iliosacral screw fixation for the treatment of bilateral sacral fractures

Background

Bilateral sacral fractures result in traumatic disruption of the posterior pelvic ring. Treatment for unstable posterior pelvic ring fractures should aim for fracture reduction and rigid fixation to facilitate early mobilization. Iliosacral screw fixation (ISF) and lumbopelvic fixation (LPF) were recommended for the treatment of these injuries. No algorithm or gold standard exists for surgery of these fractures.

Purpose

The purpose of this study was to evaluate the differences between ISF and LPF in bilateral sacral fractures regarding intraoperative procedures, complications and postoperative mobilization. The secondary aim was to determine whether demographics influence surgical treatment.

Methods

Over a 4-year period (2016–2019), 188 consecutive patients with pelvic ring injuries were treated at one academic level 1 trauma center and retrospectively identified. Fractures were classified according to the AO/OTA classification system. Seventy-seven patients were treated with LPF or ISF in combination with internal fixation of pubic rami fractures and could be included in this study. Comparisons were made between demographic and perioperative data. Infection, hematoma and hardware malpositioning were used as complication variables. Mobilization with unrestricted weight bearing was used as outcome variable. Follow-up was at least 6 months postoperatively.

Results

Operative stabilization of bilateral posterior pelvic ring injuries was performed in 77 patients. Therefore, 29 patients (females 59%) underwent LPF whereas 48 patients (females 83%) had bilateral ISF. The ISF group was older (76 yrs.) compared to the LPF group (62 yrs.) (p = 0.001), but no differences regarding BMI or comorbidities were detected. Time for surgery was reduced for patients who were treated with ISF compared to lumbopelvic fixation (73 min vs. 165 min; respectively, p < 0.001). But this did not result in reduced fluoroscopic time or radiation exposure. Overall complication rate was not different between the groups. Patients with LPF had a greater length of stay (p = 0.008) but were all weight bearing as tolerated when discharged (p < 0.001).

Conclusion

Bilateral posterior pelvic ring injuries of the sacrum can be sufficiently treated by LPF or ISF. LPF allows immediate weight bearing which may benefit younger patients and patients with an elevated risk for pneumonia or other pulmonary complications. Treatment with ISF reduces operative time, length of stay and postoperative wound infection. Elderly patients may be better suited for treatment with ISF if there is concern that the patient may not tolerate the increased operative time.

Biomechanical study of transsacral-transiliac screw fixation versus lumbopelvic fixation and bilateral triangular fixation for "H"- and "U"-type sacrum fractures with traumatic spondylopelvic dissociation: a finite element analysis study

Objective

To compare the biomechanical stability of transsacral-transiliac screw fixation and lumbopelvic fixation for “H”- and “U”-type sacrum fractures with traumatic spondylopelvic dissociation.

Methods

Finite element models of “H”- and “U”-type sacrum fractures with traumatic spondylopelvic dissociation were created in this study. The models mimicked the standing position of a human. Fixation with transsacral-transiliac screw fixation, lumbopelvic fixation, and bilateral triangular fixation were simulated. Biomechanical tests of instability were performed, and the fracture gap displacement, anteflexion, rotation, and stress distribution after fixation were assessed.

Results

For H-type fractures, the three kinds of fixation ranked by stability were bilateral triangular fixation > lumbopelvic fixation > transsacral-transiliac screw fixation in the vertical and anteflexion directions, bilateral triangular fixation > transsacral-transiliac S1 and S2 screw fixation > lumbopelvic fixation in rotation. The largest displacements in the vertical, anteflexion, and rotational directions were 0.57234 mm, 0.37923 mm, and 0.13076 mm, respectively. For U-type fractures, these kinds of fixation ranked by stability were bilateral triangular fixation > lumbopelvic fixation > transsacral-transiliac S1 and S2 screw fixation > transsacral-transiliac S1 screw fixation in the vertical, anteflexion, and rotational directions. The largest displacements in the vertical, anteflexion, and rotational directions were 0.38296 mm, 0.33976 mm, and 0.05064 mm, respectively.

Conclusion

All these kinds of fixation met the mechanical criteria for clinical applications. The biomechanical analysis showed better bilateral balance with transsacral-transiliac screw fixation. The maximal displacement for these types of fixation was less than 1 mm. Percutaneous transsacral-transiliac screw fixation can be considered the best option among these kinds of fracture fixation.

Roy-Camille Type 3 suicidal jumper's fractures: Case series and review of the literature

Background:

Roy-Camille reported only three patients in their Type 3 posttraumatic transverse sacral fracture (TSF) classification. A modified Roy-Camille classification has been already proposed by other authors suggesting further categorization of the TSFs as partially displaced or completely displaced to predict the rate of neurological recovery following lumbopelvic fixation.

Materials and Methods:

We reported three adult cases of surgical fixation of fracture–dislocation (3A and 3B) of the sacrum due to traumatic injuries and submitted to lumbopelvic posterior reconstruction. A case of a 15-year-old male patient affected by Type 3C with vascular pelvic injury was also reported. A comprehensive literature search was performed on evaluation and management of Type 3 TSFs.

Results:

In Type 3A, there is a minimal anterior dislocation and the reduction is feasible with good chance of recovery. In Type 3B, the anterior dislocation is severe, neurological deficits are present, reduction is difficult, and there is a risk of vascular injury both at the trauma and during the surgical reduction. In Type 3C, the anterior dislocation is massive, and the risk of vascular injury is very high requiring prompt vascular or endovascular treatment. Open reduction and posterior instrumentation are technically feasible in patients affected by Type 3 high TSFs.

Conclusions:

In our opinion, a modified Roy-Camille classification could be useful in the assessment of prognostic and therapeutic aspects of such fractures, In our opinion, a modified Roy-Camille classification could help assess the prognostic and therapeutic aspects of such fractures, in which the severity of the dislocation affects the surgical technique, the chance of neurological recovery, and the patient's life expectancy.

Navigated iliac screw placement may reduce radiation and OR time in lumbopelvic fixation of unstable complex sacral fractures

Purpose

Instability of the posterior pelvic ring may be stabilized by lumbopelvic fixation. The optimal osseous corridor for iliac screw placement from the posterior superior iliac spine to the anterior inferior iliac spine requires multiple ap- and lateral-views with additional obturator-outlet and -inlet views.

The purpose of this study was to determine if navigated iliac screw placement for lumbopelvic fixation influences surgical time, fluoroscopy time, radiation exposure, and complication rates.

Methods

Bilateral lumbopelvic fixation was performed in 63 patients. Implants were inserted as previously described by Schildhauer. A passive optoelectronic navigation system with surface matching on L4 was utilized for navigated iliac screw placement. To compare groups, demographics were assessed. Operative time, fluoroscopic time, and radiation were delineated.

Results

Conventional fluoroscopic imaging for lumbopelvic fixation was performed in 32 patients and 31 patients underwent the procedure with navigated iliac screw placement. No differences were found between the groups regarding demographics, comorbidities, or additional surgical procedures.

Utilization of navigation led to fluoroscopy time reduction of more than 50% (3.2 vs. 8.6 min.; p < 0.001) resulting in reduced radiation (2004.5 vs. 5130.8 Gy*cm²; p < 0.001). Operative time was reduced in the navigation group (176.7 vs. 227.4 min; p = 0.002) despite the necessity of additional surface referencing.

Conclusion

For iliac screws, identifying the correct entry point and angle of implantation requires detailed anatomic knowledge and multiple radiographic views. In our study, additional navigation reduced operative time and fluoroscopy time resulting in a significant reduction of radiation exposure for patients and OR personnel.

Posterior Stabilization of Unstable Sacral Fractures: A Single-Center Experience of Percutaneous Sacroiliac Screw and Lumbopelvic Fixation in 67 Cases

Study Design

This is a retrospective study.

Purpose

Recent advances in intraoperative imaging and closed reduction techniques have led to a shifting trend toward surgical management in every unstable sacral fracture. This study aimed to evaluate the clinicoradiological outcome of the sacroiliac (SI) screw and lumbopelvic fixation (LPF) techniques and thereby delineate the indications for each.

Overview of Literature

Optimal management guidelines for unstable sacral fractures are still lacking probably due to the rarity of these injuries and varying fixation trends.

Methods

Out of the 67 patients, 40 and 27 were in the SI and LPF groups, respectively. The electronic medical record for each patient was reviewed, including patient demographic data, mode of trauma, coexisting injuries, neurological status (Gibbon's four-grade system), Injury Severity Score, time from admission to operative stabilization, type of surgical stabilization, complications, return to the operating room, and treatment outcome measures using Majeed's functional grading system and Matta's radiological criteria. The minimum follow-up period was 2 years.

Results

Noncomminuted longitudinal injuries with normal neurology and acceptable closed reduction have undergone SI screw fixation (n=40). Irreducible, comminuted, or high transverse fractures associated with dysmorphic anatomy or neurodeficit were managed by LPF (n=27). Excellent and good Majeed and Matta scores at 86.57% and 92.54% of the patients, respectively, were postoperatively achieved.

Conclusions

Unstable sacral fractures can be effectively managed with percutaneous SI screw including vertically unstable injuries by paying strict attention to preoperative patient selection whereas LPF can be reserved for comminuted fractures, unacceptable closed reduction, associated neurodeficit, lumbosacral dysmorphism, and high transverse fractures.

The role of sagittal alignment in predicting major failure of lumbopelvic instrumentation: a biomechanical validation of lumbopelvic failure classification

STUDY DESIGN

Finite element analysis.

OBJECTIVES

To biomechanically validate the classification of lumbopelvic fixation failure using an in silico model. Even though major failure of lumbopelvic constructs has occurred more often in patients with suboptimal lumbar lordosis and sagittal balance, there has been no biomechanical validation of this classification.

METHODS

Finite element models (T10-pelvis) were created to match the average spinal-pelvic parameters of two cohorts of patients reported in Cho et al. (J Neurosurg Spine 19:445-453, 2013): major failure group (defined as rod breakage between L4 and S1, failure of S1 screws and prominence of iliac screws requiring removal) and non-failure group. A moment was applied at the T10 superior endplate to simulate gravimetric loading in a standing position.

RESULTS

Due to differences in the alignment of spinopelvic parameters between normal and failed spines in the presence of a fixed gravity line, the major failure cohort in this study observed a 20% higher load and 18% greater instability. As a result, the rod and screw stress in the major failure cohort increased by 20% and 42%, respectively, in comparison to the non-failure cohort.

CONCLUSIONS

The greater mechanical demand on the posterior rods in the lower lumbar spine in the major failure cohort further emphasizes the importance of proper sagittal alignment. This finite element analysis validates the classification of lumbopelvic fixation failure.

Is S1 Alar Iliac Screw a Feasible Option for Lumbosacral Fixation?: A Technical Note

Nonunion at the lumbosacral junction is a classic complication of long construct and deformity corrections. Iliac fixations have been extensively studied in the literature and have demonstrated superior biomechanical proprieties and lower complication rates. S2 alar iliac screws address the drawbacks of classical iliac screws but demonstrate similar biomechanical advantage. The main aim of this paper was to describe the S1 alar iliac (S1AI) screw fixation technique while evaluating our early results. S1AI screw fixation technique has the advantage of being able to achieve pelvic fixation without dissection to the S2 pedicle entry and is therefore a viable option for salvage of a failed S1 promontory screw.

Suicidal jumper's fracture - sacral fractures and spinopelvic instability: a case series

BACKGROUND

Sacral fractures with spinopelvic dissociation are rare, and hard to diagnose and treat. Fractures with a H- or U-shaped line are severely unstable, due to a dissociation of the spine and of the upper body of the sacrum from the pelvis. They are commonly due to high-energy trauma events, with severe neurological injuries in 80% of cases.

CASES PRESENTATION

Five polytraumatized Caucasian patients, three women and two men (mean age: 34 years old) with spinopelvic dissociation were selected. All patients underwent level I-II examinations with radiographs and computed tomography total-body scans; all patients needed damage-control procedures. Sacral fractures were classified according to Denis and Roy-Camille classifications, and neurologic injuries of cauda equina according to Gibbons classification. Patients' outcome was analyzed with the Majeed score. Definitive surgical treatment was appropriate for two patients (lumbar-pelvic fixation or transverse bar). Clinical and radiographic outcomes were analyzed periodically. Four patients survived, all of them suffered severe neurologic deficits. One case of osteomyelitis was treated with the removal of the fixation implants 23 months after the accident.

CONCLUSIONS

Diagnosis of spinopelvic dissociation is frequently overlooked due to the severe associated injuries affecting these patients. In cases of a fall from high height, this lesion should be investigated with a lateral sacral radiographic view and computed tomography scan of the pelvis. If untreated, it can lead to severe and progressive neurologic deficit with muskuloskeletal deformities and persistent pain. Early decompression treatment is controversial, but an early lumbopelvic fixation is recommended. A correct diagnosis and early treatment can reduce morbidity and strongly improve the outcome of these patients.

Fate of S2-Alar-Iliac Screws After 12-Month Minimum Radiographic Follow-up: Preliminary Results

BACKGROUND

S2-alar-iliac (S2AI) screws are 1 technique for lumbopelvic fixation to improve fusion rates across the lumbosacral junction that has gained wider acceptance. The S2AI screw crosses the cortical surfaces of the sacroiliac joint (SIJ), which may improve the biomechanical strength of the instrumentation.

OBJECTIVE

To report preliminary radiographic outcomes of patients who underwent lumbopelvic fixation with S2AI screws with a minimum 12-month follow-up.

METHODS

We retrospectively reviewed adult patients who underwent lumbopelvic fixation with S2AI screws. Patients with computed tomography (CT) scans obtained preoperatively and ≥12 months postoperatively were reviewed to determine whether there was S2AI screw backout or breakage, periscrew lucency, or SIJ degeneration, and to assess L5-S1 fusion status.

RESULTS

Twenty-six S2AI screws in 13 patients were evaluated (mean follow-up 24.8 months [14-52 months]). Nine patients had L5-S1 interbody grafts. Partial periscrew lucency was identified in 7 S2AI screws (27%) in 5 patients (38%), and L5-S1 fusion occurred in 92% of patients. L5-S1 nonunion was seen in 1 patient (8%), who had evidence of bilateral screw loosening in the sacral portion. Four patients with screw loosening had an osseous L5-S1 fusion. No patients had radiographic evidence of progression of SIJ degeneration, experienced screw backout or breakage, required reoperation for L5-S1 nonunion, or had S2AI screw-related complication.

CONCLUSION

S2AI screws maintained their integrity without causing SIJ degeneration or major screw-related complications in this small retrospective series with short follow-up. Long-term results are needed to evaluate the durability of S2AI screws over time.

Outcomes of lumbopelvic fixation in the treatment of complex sacral fractures using minimally invasive surgical techniques

BACKGROUND CONTEXT

Complex sacral fractures with vertical and anterior pelvic ring instability treated with traditional fixation methods are associated with high rates of failure and poor clinical outcomes. Supplemental lumbopelvic fixation (LPF) has been applied for additional stability to help with fracture union.

PURPOSE

The study aimed to determine whether minimally invasive LPF provides reliable fracture stability and acceptable complication rates in cases of complex sacral fractures.

STUDY DESIGN/SETTING

This is a retrospective cohort study at a single level I trauma center.

PATIENT SAMPLE

The sample includes 24 patients who underwent minimally invasive LPF for complex sacral fracture with or without associated pelvic ring injury.

OUTCOME MEASURES

Reoperation for all causes, loss of fixation, surgical time, transfusion requirements, length of hospital stay, postoperative day at mobilization, and mortality were evaluated.

METHODS

Patient charts from 2008 to 2014 were reviewed. Of the 32 patients who underwent minimally invasive LPF for complex sacral fractures, 24 (12 male, 12 female) met all inclusion and exclusion criteria. Outcome measures were assessed with a retrospective chart review and radiographic review. The authors did not receive external funding for this study.

RESULTS

Acute reoperation was 12%, and elective reoperation was 29%. Two (8%) patients returned to the operating room for infection, one (4.2%) required revision for instrumentation malposition, and seven (29%) underwent elective removal of instrumentation. No patient experienced failure of instrumentation or loss of correction. Average surgical time was 3.6 hours, blood loss was 180 mL, transfusion requirement was 2.1 units of packed red blood cells, and postoperative mobilization was on postoperative day 5. No mortalities occurred as a result of the minimally invasive LPF procedure.

CONCLUSIONS

Compared with historic reports of open LPF, our results demonstrate reliable maintenance of reduction and acceptable complication rates with minimally invasive LPF for complexsacral fractures. The benefits of minimally invasive LPF may be offset with increased elective reoperations for removal of instrumentation.

Lumboiliac fixation in lumbosacral dislocation and associated injuries of the pelvis and lumbosacral junction: a long-term radiological and clinical follow-up

INTRODUCTION

The goal of the study was to evaluate both clinical and radiological outcome of a consecutive series of 11 patients submitted to lumboiliac fixation after lumbopelvic disjunction or associated injuries of the pelvis and lumbosacral tract in mid- and long-term follow-up.

MATERIAL AND METHODS

The following were evaluated from clinical charts: damage control preoperative procedures, surgery, and pre-, intra- and post-operative complications; imaging was also evaluated from the preoperative assessment to the final follow-up (4 to 13.2 years; average 7.2 years).

RESULTS

One patient died a few days after surgery; therefore, long-term follow-up was possible in 10 patients. One of the 10 patients could be evaluated only radiologically because he was non-compliant due to severe mental illness. There were four early complications: one patient had a massive pulmonary embolism, which was fatal; one had wound dehiscence; one developed pulmonary infection and one had caecal fistula, which was repaired by the general surgeon. Late complications were as follows: three patients required hardware removal or substitution because of deep infection (after 1year), system breakage (after 9 years) and screws loosening (after 7 years). Clinical evaluation was available in nine patients and was assessed using Oswestry forms and a Visual Analogue Scale (VAS). All patients were able to walk at least 1 kilometre without external support, two patients were using pain medication regularly and three patients were classified with severe disability at final follow-up. Degenerative changes in the joints close to the fused area were observed in two patients more than 10 years after the operation, but the correlation with surgery is questionable.

DISCUSSION

Lumbopelvic disjunctions generally follow high-energy trauma often involving internal thoracic and abdominal organs; therefore, a well-trained team approach is mandatory to preserve patient life and to provide adequate treatment of skeletal injuries. Mechanical complications may occur several years after surgery, thus a long-term follow-up is mandatory.

CONCLUSIONS

Lumbopelvic fixation is an effective surgical technique for treatment of spinopelvic disjunction. The patient numbers in this series, and in the literature in general, are low; therefore, a multicentre study is advisable to give evidence and statistical importance to our findings.

Effect of the subcutaneous route for iliac screw insertion in lumbopelvic fixation for vertical unstable sacral fractures on the infection rate: A retrospective case series

OBJECTIVE

To report the perioperative results and surgical outcomes of patients with vertical unstable sacral fractures who underwent lumbopelvic fixation through a modified subcutaneous route for iliac screw fixation.

SUMMARY OF BACKGROUND DATA

Treating vertical unstable sacral fractures is still challenging for orthopedic surgeons. Among various methods for treating these fractures, lumbopelvic fixation provides a high reduction quality and promising stability for early weight-bearing ambulation. However, wound healing disturbance and surgical site infection (SSI) are the drawbacks of this extensive technique, especially after inserting iliac screws.

METHODS

Here, we provide an alternative subcutaneous route for iliac screw insertion during lumbopelvic fixation surgery to lessen soft tissue retraction and injury, and thus decrease soft tissue complications.

RESULTS

Using this modified technique, 28 patients with vertical unstable sacral fractures were treated between 2012 and 2014. One patient had an SSI (infection rate: 3.5%). All fractures were united with a mean sacral kyphosis correction angle of 10.5°. The mean Majeed score of the 17 patients during the 12-month follow-up was 84.5.

CONCLUSIONS

The subcutaneous route for iliac screw insertion is a simple, safe, and effective technique when performing lumbopelvic fixation for vertical unstable sacral fractures.