Triangular osteosynthesis and iliosacral screw fixation for unstable sacral fractures: a cadaveric and biomechanical evaluation under cyclic loads

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.

L4 fixation is not necessary in L5-Iliac spinopelvic fixation after trauma, but coadjutant transilio-transsacral fixation is

INTRODUCTION

Spinopelvic dissociation (SPD) is a severe injury characterized by a discontinuity between the spine and the bony pelvis consisting of a bilateral longitudinal sacral fracture, most of the times through sacral neuroforamen, and a horizontal fracture, usually through the S1 or S2 body. The introduction of the concept of triangular osteosynthesis has shown to be an advance in the stability of spinopelvic fixation (SPF). However, a controversy exists as to whether the spinal fixation should reach up to L4 and, if so, it should be combined with transiliac-transsacral screws (TTS).

OBJECTIVE

The purpose of this study is to compare the biomechanical behavior in the laboratory of four different osteosynthesis constructs for SPD, including spinopelvic fixation of L5 versus L4 and L5; along with or without TTS in both cases.

MATERIAL AND METHODS

By means of a formerly described method by the authors, an unstable standardized H-type sacral fracture in twenty synthetic replicas of a male pelvis articulated to the lumbar spine, L1 to sacrum, (Model: 1300, SawbonesTM; Pacific Research Laboratories, Vashon, WA, USA), instrumented with four different techniques, were mechanically tested. We made 4 different constructs in 5 specimen samples for each construct. Groups: Group 1. Instrumentation of the L5-Iliac bones with TTS. Group 2. Instrumentation of the L4-L5-Iliac bones with TTS. Group 3. Instrumentation of L5-Iliac bones without TTS. Group 4: Instrumentation of L4-L5-Iliac bones without TTS.

RESULTS AND CONCLUSIONS

According to our results, it can be concluded that in SPD, better stability is obtained when proximal fixation is only up to L5, without including L4 (alternative hypothesis), the addition of transiliac-transsacral fixations is essential.

Sacroiliac versus transiliac-transsacral screw osteosynthesis in osteoporotic pelvic fractures: a biomechanical comparison

INTRODUCTION

Pelvic fractures were often associated with high-energy trauma in young patients, but data show a significant increase in osteoporotic pelvic fractures in old age due to the progressive demographic change. There is an ongoing discussion about the best fixation techniques, which are ranging from lumbopelvic fixation to sacral bars or long transiliac-transsacral (TITS) screws. This study analyzes TITS screw osteosynthesis and sacroiliac screw osteosynthesis (SI), according to biomechanical criteria of fracture stability in osteoporotic human pelvic cadavers ex vivo.

METHODS

Ten osteoporotic cadaveric pelvises were randomized into two groups of 5 pelvises each. An FFP-IIc fracture was initially placed unilaterally and subsequently surgically treated with a navigated SI screw or a TITS screw. The fractured side was loaded in a one-leg stance test setup until failure. Interfragmentary movements were assessed by means of optical motion tracking.

RESULTS

No significant difference in axial stiffness were found between the SI and the TITS screws (21.2 ± 4.9 N and 18.4 ± 4.1 N, p = 0.662). However, there was a significantly higher stability of the fracture treatment in the cohort with TITS-screws for gap angle, flexion, vertical movement and overall stability. The most significant difference in the cycle interval was between 6.000 and 10.000 for the gap angle (1.62 ± 0.25° versus 4.60 ± 0.65°, p = 0.0001), for flexion (4.15 ± 0.39 mm versus 7.60 ± 0.81 mm, p = 0.0016), interval 11.000-15.000 for vertical shear movement (7.34 ± 0.51 mm versus 13.99 ± 0.97 mm, p < 0.0001) and total displacement (8.28 ± 0.66 mm versus 15.53 ± 1.07 mm, p < 0.0001) for the TITS and the SI screws.

CONCLUSIONS

The results of this biomechanical study suggest a clear trend towards greater fracture stability of the TITS screw with significantly reduced interfragmentary movement. The application of a TITS screw for the treatment of the osteoporotic pelvic ring fracture may be prioritized to ensure the best possible patient care.

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.

Triangular Osteosynthesis as a Treatment of Lumbopelvic Dissociation with Acute Cauda Equina Syndrome in an 11-Year-Old Patient

This case offers a safe and effective method for treating lumbopelvic dissociation in a pediatric patient with cauda equina syndrome using a triangular osteosynthesis construct. After a high-speed accident, an 11-year-old girl was admitted to the hospital with bowel and bladder incontinence and bilateral lower extremity weakness. The orthopaedic trauma and spine teams elected for surgical treatment with a triangular osteosynthesis construct, a procedure usually reserved for adults. The surgery was uncomplicated, and the patient experienced complete resolution of her preoperative symptoms. She is doing well over 1-year postoperatively, with full neurologic recovery, maintained reduction, bony healing, and subsequent implant removal. To our knowledge, this is the youngest reported case of lumbopelvic dissociation treated in this manner and represents a viable treatment option.

[Sacral H-shaped fractures between traumatic, insufficiency and fatigue fractures : Similarities, differences and controversies]

In the basic entirety of stress fractures, insufficiency fractures are defined as fractures caused by prolonged normal or physiological loading of a bone with insufficient elastic resistance. This clearly distinguishes it from fatigue fractures, in which excessive loads are continuously applied to a bone with normal elastic resistance. According to Pentecost (1964) both entities of stress fracture result from "the inherent inability of the bone to withstand stress applied without violence in a rhythmical, repeated, subthreshold manner". This distinguishes them from acute traumatic fractures. In the clinical routine these differences are not always so clearly presented. The example of the H‑shaped sacral fracture is used to illustrate the relevance of a clear terminology. In this context, current controversies in the treatment of sacral insufficiency fractures are discussed.

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.

External Fixation for Fracture Stabilization of the Sacrum in 15 Dogs

This study aimed to evaluate the feasibility, complications, and outcomes of external fixation (EF) for the treatment of sacral fractures in dogs, either as a primary fixation system or as a complementary technique. A total of 15 dogs with sacral fractures were surgically treated using different EF configurations, either as primary or secondary stabilization. The results were evaluated for the extent of fracture reduction, stability during treatment, complications, and bone healing. In most cases, the outcomes were excellent in terms of bone healing, neurological conditions, and pain assessment. The mean bone healing time was 9.45 ± 5.66 weeks. One (6.66%) patient presented a complication due to the technique. In conclusion, the use of EF should be considered for the stabilization of sacral fractures because of its minimal invasiveness, stability, and ease of application.

Effects of Iliosacral Joint Immobilization on Walking after Iliosacral Screw Fixation in Humans

BACKGROUND

Pelvis fractures are commonly stabilized by surgical implants to facilitate their healing. However, such implants immobilize the iliosacral joint for up to a year until removal. We report how iliosacral joint immobilization affects the walking of patients.

METHODS

The gaits of patients with immobilized sacroiliac joints after unstable pelvic fracture (n = 8; mean age: 45.63 ± 23.19; five females and three males) and sex- and age-matched healthy control individuals (n = 8; mean age: 46.50 ± 22.91; five females and three males) were recorded and analyzed using a motion capture system. The forces between the tread and feet were also recorded. Standard gait parameters as well as dynamic patterns of joint angles and moments of the lower extremities were analyzed using the simulation software OpenSim.

RESULTS

With the exception of hip extensor strength, the monitored joint parameters of the patients showed task-dependent deviations during walking, i.e., plantarflexor force was increased when stepping on an elevated surface, as were hip flexion and extensor moments, knee flexion and extensor moments, as well as ankle dorsiflexion and the associated negative plantarflexor force during stance on the elevated surface.

CONCLUSIONS

Iliosacral joint fixation causes reduced forward and upward propulsion and requires an extended range of hip motion in the sagittal plane. Patients show significant mobility limitation after iliosacral screw fixation.

Biomechanical effects of S1 sacroiliac screws versus S2 sacroiliac screws on sacroiliac screws combined with a lumbar iliac fixation in the treatment of vertical sacral fractures: a biomechanical finite element analysis

OBJECTIVE

To examine the impact of sacroiliac screw position and length on the biomechanical properties of triangular osteosynthesis in treating unilateral vertical sacral fractures and provide a clinical reference.

METHODS

Unilateral Denis type II sacral fractures were modelled using finite elements to represent Tile C pelvic ring injuries. Six sacroiliac screws were used with iliolumbar fixation patterns to fix the sacral fractures, and the sacral stability, maximum pressure, and stress distribution were compared among the internal fixation modalities.

RESULTS

The best vertical stability of the internal fixation model was achieved when the S1 segment was fixed with lengthened sacroiliac screws, followed by when the S1 segment was fixed using normal sacroiliac screws. There was no significant difference in vertical stability between the S1 + S2 dual-segment fixation model and the S1-segment fixation model. The maximum pressure under a vertical force of 600 N showed a trend of L5LS1 < L5NS1 < L5LS12 < L5LS2 < L5NS2 < L5NS12.

CONCLUSIONS

In unilateral vertical sacral fractures (Denis II) treated with triangular osteosynthesis using triangular jointing combined with unilateral iliolumbar + sacroiliac screw fixation, the use of a single lengthened sacroiliac screw for the S1 segment is recommended to achieve the best vertical stability of the sacrum with less maximum compression on the internal fixation components. If it is not possible to apply a lengthened sacroiliac screw, the use of a normal sacroiliac screw for the S1 segment is recommended. Adding an S2 screw does not significantly increase the vertical stability of the sacrum.

Consensus for management of sacral fractures: from the diagnosis to the treatment, with a focus on the role of decompression in sacral fractures

BACKGROUND

There is no evidence in the current literature about the best treatment option in sacral fracture with or without neurological impairment.

MATERIALS AND METHODS

The Italian Pelvic Trauma Association (A.I.P.) decided to organize a consensus to define the best treatment for traumatic and insufficiency fractures according to neurological impairment.

RESULTS

Consensus has been reached for the following statements: When complete neurological examination cannot be performed, pelvic X-rays, CT scan, hip and pelvis MRI, lumbosacral MRI, and lower extremities evoked potentials are useful. Lower extremities EMG should not be used in an acute setting; a patient with cauda equina syndrome associated with a sacral fracture represents an absolute indication for sacral reduction and the correct timing for reduction is "as early as possible". An isolated and incomplete radicular neurological deficit of the lower limbs does not represent an indication for laminectomy after reduction in the case of a displaced sacral fracture in a high-energy trauma, while a worsening and progressive radicular neurological deficit represents an indication. In the case of a displaced sacral fracture and neurological deficit with imaging showing no evidence of nerve root compression, a laminectomy after reduction is not indicated. In a patient who was not initially investigated from a neurological point of view, if a clinical investigation conducted after 72 h identifies a neurological deficit in the presence of a displaced sacral fracture with nerve compression on MRI, a laminectomy after reduction may be indicated. In the case of an indication to perform a sacral decompression, a first attempt with closed reduction through external manoeuvres is not mandatory. Transcondylar traction does not represent a valid method for performing a closed decompression. Following a sacral decompression, a sacral fixation (e.g. sacroiliac screw, triangular osteosynthesis, lumbopelvic fixation) should be performed. An isolated and complete radicular neurological deficit of the lower limbs represents an indication for laminectomy after reduction in the case of a displaced sacral fracture in a low-energy trauma associated with imaging suggestive of root compression. An isolated and incomplete radicular neurological deficit of the lower limbs does not represent an absolute indication. A worsening and progressive radicular neurological deficit of the lower limbs represents an indication for laminectomy after reduction in the case of a displaced sacral fracture in a low-energy trauma associated with imaging suggestive of root compression. In the case of a displaced sacral fracture and neurological deficit in a low-energy trauma, sacral decompression followed by surgical fixation is indicated.

CONCLUSIONS

This consensus collects expert opinion about this topic and may guide the surgeon in choosing the best treatment for these patients.

LEVEL OF EVIDENCE

IV.

TRIAL REGISTRATION

not applicable (consensus paper).

Sacral Fractures: A Review

At the cornerstone of the pelvis and spine, the sacrum may be fractured in patients of all ages. Sacral fractures range from high-energy injuries, with mortality rates of up to 18%, to low-energy insufficiency fractures. The intricate geometry of the sacrum, the breadth of morphotypes, and the presence of congenital anomalies all can complicate the treatment of these fractures. Agreement on the surgical indications for these injuries is limited. This narrative review aims to update orthopedic surgeons on the clinical evaluation and the non-surgical and surgical management of these fractures.

Biomechanical comparison of four triangular osteosynthesis fixations for unilateral vertical sacral fractures

To compare the stability and biomechanical characteristics of four commonly used triangular osteosynthesis techniques to treat unilateral vertical sacral fractures and provide a clinical application reference. Finite element models of Tile C-type pelvic ring injury (unilateral Denis II sacral fracture) were produced. In four models, sacral fractures were fixed with a combination of unilateral L5, unilateral L4, and L5 iliac lumbar fixation with lengthened or normal sacroiliac screws. The biomechanical properties of the four fixation models were measured and compared under bipedal stance and lumbar rotation. The fixation stability of the model with the lengthened sacroiliac screw was excellent, and the fracture end was stable. The stability of fixation using unilateral L4 and L5 segments was close to that of unilateral L5 segment fixation. Triangular osteosynthesis transverse stabilization devices using lengthened sacroiliac screws can increase the vertical stability of the sacrum after internal fixation and increase the stability of the fracture. When triangular osteosynthesis lumbar fixation segments were selected, simultaneous fixation of L4 and L5 segments versus only L5 segments did not significantly enhance the vertical stability of the sacrum or the stability of the fracture end.

Spinopelvic In Situ Fixation and Early Mobilization: A Case Report and Literature Review

Pelvic fractures with sacroiliac extension are significant and complicated orthopedic injuries that pose a challenge in management and favorable outcomes. A 50-year-old obese female presented after a motor vehicle accident with pelvic fracture lateral compression. The patient underwent anterior external fixation with a left sacroiliac screw (SIS) on the next day of admission and was kept in a non-weight-bearing state. During her hospital stay, she developed deep vein thrombosis (DVT) and was treated. During the follow-up on the sixth week, the patient was not complying with her immobilization instructions and was exposing the left lower limb to weight bearing. The radiologic evaluation demonstrated a pulled-out SIS with a stable fracture. Considering that the patient was obese, had a history of DVT and COVID-19 infection, and the fracture was minimally displaced, it was decided to perform a spinopelvic in-situ fixation from L4 to S2 and augment it with a left SIS. The patient tolerated the surgery well and was referred to physiotherapy for early mobilization with full weight bearing. During her six-month and two-year follow-ups, she was well mobilized with no active complaints, and radiographic studies showed good healing, no displacement, no signs of instability, and a stable construct. Our case report presents a very rare and difficult but successful management of a fracture displacement in a non-compliant patient with one pulled-out screw through fast-tracked in situ spinopelvic fixation with early mobilization and full weight bearing. To our knowledge, this is one of the rare reports detailing a patient undergoing in situ spinopelvic fixation due to minimally displaced fracture with comorbidities such as obesity and DVT. Our report demonstrates the viability of accepting pulled-out screws, with respect to the patient's health, the fracture's geometry, a quick follow-up in situ spinopelvic fixation, early mobilization, full weight-bearing outcomes, and a lower risk for complications.

Management of C0 Sacral Fractures Based on the AO Spine Sacral Injury Classification: A Narrative Review

The Arbeitsgemeinschaft fur Osteosynthese fragen Spine Sacral Injury Classification hierarchically separates fractures based on their injury severity with A-type fractures representing less severe injuries and C-type fractures representing the most severe fracture types. C0 fractures represent moderately severe injuries and have historically been referred to as nondisplaced "U-type" fractures. Injury management of these fractures can be controversial. Therefore, the purpose of this narrative review is to first discuss the Arbeitsgemeinschaft fur Osteosynthese fragen Spine Sacral Injury Classification System and describe the different fracture types and classification modifiers, with particular emphasis on C0 fracture types. The narrative review will then focus on the epidemiology and etiology of C0 fractures with subsequent discussion focused on the clinical presentation for patients with these injuries. Next, we will describe the imaging findings associated with these injuries and discuss the injury management of these injuries with particular emphasis on operative management. Finally, we will outline the outcomes and complications that can be expected during the treatment of these injuries.

Open Posterior Reduction and Stabilization of AO Spine C3 Sacral Fractures

AO Spine C3 sacral fractures are defined by separation of the spine including S1 from the pelvic ring and are usually result of a high-energy injury. Besides their high biomechanical instability and high rate of associated neurological impairment, these fractures are often extremely difficult to reduce due to severe bony impaction and dislocation. Additional difficulties in management of these fractures arise from only a thin-layer of soft-tissue coverage overlying the injured area.

Modified triangular osteosynthesis in the treatment of bilateral sacroiliac joint dislocation

Bilateral sacroiliac joint dislocation is a rare injury associated with rotational and vertical instability of the pelvic ring. The ideal strategy for the reduction and fixation of this injury is poorly described in the current literature. Triangular osteosynthesis provides multiplanar stability to the posterior pelvic ring allowing early weight bearing. We present the case of a young female with a bilateral sacroiliac joint dislocation who underwent a modified bilateral triangular osteosynthesis, using S1 pedicle screws to improve the reduction of the sacroiliac joint.

Robotic guidance for percutaneous placement of triangular osteosynthesis in vertically unstable sacrum fractures: a single-center retrospective study

BACKGROUND

To evaluate the effectiveness and safety of robot-aided percutaneous triangular osteosynthesis combined with close reduction for vertically unstable sacrum fractures (VUSFs).

METHODS

The data on 21 patients of the VUSF were retrospectively analyzed from November 2016 to January 2021. According to Denis classification, there were 3 cases in zone I, 11 cases in zone II, and 7 case in zone III. The main perioperative indicators were recorded. The maximal angulation and displacement deviations of the screws were analyzed by comparing the planned trajectory with the actual position. Postoperative X-ray radiographs and CT scans were obtained for evaluating the reduction quality. Functional outcome was scored with Majeed criterion.

RESULTS

Fourteen patients of the unilateral VUSF and 7 patients of the bilateral VUSF underwent unilateral and bilateral triangular osteosynthesis with robotic assistance, respectively. No intraoperative neurovascular injuries and postoperative infection occurred. All patients were followed up for at least 12 months. The average operation time of posterior pelvic ring was 111.4 min, with the mean intraoperative bleeding of 110.5 ml. A total of 58 pedicle and iliosacral screws were implanted with robotic assistance. Of those, 52 screws were in the cancellous bone except 4 pedicle and 2 iliosacral screws cutting the cortical bone. The angulation and displacement deviations of the screws were 4.2° ± 2.5° and 1.7 ± 0.9 mm, respectively. The average displacement of the sacral fracture was reduced from 19.7 mm preoperatively to 3.1 mm postoperatively. According to Matta's criterion, the reduction quality was graded as "excellent" in 13 patients and "good" in 8. All sacral fractures healed within 6 months except one fracture with nonunion. The mean Majeed score at the last follow-up was 89.6.

CONCLUSIONS

Robot-aided triangular osteosynthesis combined with close reduction provide a safe and reliable option for percutaneous treatment of the fresh VUSF, with a high accuracy of iliosacral and pedicle screw implantation except insertion of iliac screws. Meanwhile, the technique may help to reduce incision-related complications.

Traumatic spinopelvic dissociation: A case series

Introduction

Spinopelvic dissociation was described first in 1969. It is an injury characterized by the separation of the lumbar spine, with parts of the sacrum, from the rest of the sacrum and pelvis with the appendicular skeleton through the sacral ala. Spinopelvic dissociation has an incidence of approximately 2.9% of all pelvic disruptions and corresponds with high-energy trauma. The objective of this study was to review and analyze a case series of spinopelvic dissociations that were treated in our institution from May 2016 to December 2020.

Methods

This was a retrospective study reviewing medical records of a series of cases with spinopelvic dissociating. A total of nine patients were encountered. Demographic data including gender and age were analyzed with the mechanism of injury, fracture characteristics, and classifications in addition to neurological deficits. Fractures were classified by the AO Spine Sacral Classification System. Moreover, neurological deficits were classified using the Gibbon's classification score. Finally, the Majeed score was utilized for the assessment of the functional outcome after the injury.

Results

A total of nine patients with spinopelvic dissociation were encountered, seven males and two females. Seven patients were due to motor vehicle accidents, one patient was due to a suicidal attempt, and one patient was due to seizure. Four patients suffered from neurological deficits. One patient needed an intensive care unit admission. Spinopelvic fixation was done for all patients. One patient had surgical wound infection with wound dehiscence, one had infected instruments with confirmed spine osteomyelitis, and one had a focal neurological deficit. Six patients went on to heal and showed complete neurological improvements.

Conclusion

Spinopelvic dissociation injuries represent a variety of injuries that are commonly associated with high-energy trauma. The triangular fixation method has proven to be a stable construct in dealing with such injuries.

Comparative retrospective study of triangular osteosynthesis with and without robotic assistance for unilateral unstable sacral fractures combined with lumbosacral junction injuries

BACKGROUND

To compare the clinical efficacy of unilateral unstable sacral fractures (USFs) involving the lumbosacral region treated with and without robot-aided triangular osteosynthesis (TOS).

METHODS

Patients of the unilateral USF combined with the ipsilateral lumbosacral junction injury (LSJI) treated with TOS were retrospectively analyzed and divided into two groups: the robot group (TOS with robotic assistance) and the conventional group (TOS with open procedure). Screw placement was assessed using the modified Gras criterion. Patients were followed up with routine visits for clinical and radiographic examinations. At the final follow-up, clinical outcomes were recorded and scored using the Majeed scoring system.

RESULTS

Eleven patients in the robot group and seventeen patients in the conventional group were recruited into this study. Significant differences in surgical bleeding (P < 0.001) and fluoroscopy time (P = 0.002) were noted between the two groups. Operation time (P = 0.027) and fracture healing time (P = 0.041) was shorter in the robot group. There was no difference in postoperative residual displacement between the two groups (P = 0.971). According to the modified Gras criterion, the percentages of grade I for sacroiliac screws in the two groups were 90.9% (10/11) and 70.6% (12/17), and for pedicle screws were 100% (11/11) and 100% (17/17), respectively. The rate of incision-related complications was 0% (0/11) in the robot group and 11.8% (2/17) in the conventional group. Statistical differences were shown on the Majeed criterion (P = 0.039), with higher scores in the robot group.

CONCLUSION

TOS with robotic assistance for the treatment of unilateral USFs combined with ipsilateral LSJIs is safe and feasible, with the advantages of less radiation exposure and fewer incision-related complications.

Biomechanical tests and finite element analyses of pelvic stability using bilateral single iliac screws with different channels in lumbo-iliac fixation

Background

In lumbo-iliac fixation, the iliac screw can be placed in several locations and directions. There is no uniform standard for the placement of a single iliac screw. Biomechanical tests and finite element analyses were used to compare the effect of bilateral single iliac screws with three channels on pelvic stability to determine the best channel.

Methods

Five embalmed adult cadaver pelvic specimens were selected. An unstable Tile C1 pelvic injury model was established. Lumbo-iliac fixation for the treatment of left sacral Denis II fracture includes the following: three channels of bilateral, single iliac screws (channel A from posterior superior iliac spine (PSIS) to anterior inferior iliac spine (AIIS), channel B from 1 cm medial and 1 cm caudal of PSIS to AIIS, and channel C from 2 cm below PSIS to AIIS). Biomechanical testing was performed for stiffness evaluations. A finite element model was established to study the stress distribution of the model and the maximum von Mises stress of internal fixation.

Results

Biomechanical tests revealed that under vertical compression loading. The compressive stiffness fixed by channel B (246.15 ± 27.85 N/mm) was better than that fixed by channel A and channel C. Under torsional load, the torsional stiffness fixed by channel B (2.234 ± 0.223 N·m/°) was stronger than that fixed by channel A and channel C. However, there was no significant difference in terms of compressive and torsional stiffness between channel B and channel A (P &gt; 0.05). Finite element analyses conformed that the maximum von Mises stress of the internal fixator fixed in channel B under the conditions of vertical, forwards bending, backwards extension, left bending, left rotating, and right bending (213.98 MPa, 338.96 MPa, 100.63 MPa, 297.06 MPa, 200.95 MPa and 284.75 MPa, respectively) was significantly lower than those fixed in channel A and channel C.

Conclusions

The construct stiffness of the channel from 1 cm medial and 1 cm caudal of PSIS to AIIS is better than that of the other two channels. This channel has the advantages of good biomechanical stability, small maximum von Mises stress of internal fixation.

Technical Note on Placement of Low-Profile Triangular Osteosynthesis for Unstable Posterior Pelvic Ring Injuries

SUMMARY

Triangular osteosynthesis is a technique used to stabilize posterior pelvic ring injuries. Conventional triangular fixation can be problematic for several reasons, including the need for advanced skill sets to place instrumentation, difficulty with pelvic reduction and placing the connecting construct, and prominent instrumentation. The purpose of this study is 2-fold: (1) to describe in detail a technique for lumbopelvic fixation using implants that are easy to connect, allow distraction for complex lumbosacral displacements, and are placed in a location minimizing soft tissue prominence and (2) to present our initial case series using this technique. We present a retrospective review of 18 consecutively treated patients with this technique. Inclusion criteria were patients with complete disruption through the sacrum or sacroiliac joint from blunt trauma (OTA/AO type C injuries). Outcomes included pelvic reduction/malreduction, wound healing, and complications. Fourteen patients underwent unilateral fixation (81%), and 4 patients underwent bilateral fixation (19%). All patients (18 of the 18) had a well-reduced pelvis after fixation. No patient (0%) required a return trip to the operating room for loss of reduction/malreduction, wound breakdown, or implant failure. This study presents an updated technique for a low-profile triangular osteosynthesis construct with straightforward application for unstable posterior pelvic ring injuries. This technique does not require rod bending, results in a consistently more recessed iliac screw and connecting rod, and can be used in a wide variety of unstable posterior pelvic ring injuries, including comminuted sacral fractures, L5/S1 facet fractures, and vertical shear injuries.

Management of a rare case of isolated U-shaped displaced sacral fracture in a young female high school student

Sacral fractures in young healthy patients are usually linked to high-energy trauma. They are often associated with multiple other injuries. Isolated sacral fractures are rare and can be easily missed in the absence of other surrounding pelvic or spinal injuries. In this article, we present a rare case of isolated U-shaped displaced sacral fracture despite the high-energy mechanism of injury being missed on initial presentation. This is a 17-year-old healthy female who presented to the emergency department after falling from five-meter height. She complained of lower back pain and inability to ambulate. Physical examination revealed significant sacral tenderness, bilateral lower limb weakness and hypoesthesia, anesthesia of the saddle area, weak anal tone and absent anal reflex. Initial radiographs showed no apparent fractures. Further imaging by pelvic computed tomography, however, revealed an isolated U-shaped displaced sacral fracture. The patient was treated by decompression and lumbopelvic fixation by triangular osteosynthesis and iliosacral screw. This fixation method restored stability of the spinopelvic junction and allowed for early mobilization. At her 18-month follow-up visit, she showed minimal disability score (10%) on the Oswestry Disability Index. In conclusion, sacral fractures are considered exceedingly rare to occur in isolation and in young healthy patients.

Trans-sacral screw fixation of posterior pelvic ring injuries: review and expert opinion

Posterior pelvic ring injuries (i.e., sacro-iliac joint dislocations, fracture-dislocations, sacral fractures, pelvic non-unions/malunions) are challenging injury patterns which require a significant level of surgical training and technical expertise. The modality of surgical management depends on the specific injury patterns, including the specific bony fracture pattern, ilio-sacral joint involvement, and the soft tissue injury pattern. The workhorse for posterior pelvic ring stabilization has been cannulated iliosacral screws, however, trans-sacral screws may impart increased fixation strength. Depending on injury pattern and sacral anatomy, trans-sacral screws can potentially be more beneficial than iliosacral screws. In this article, the authors will briefly review pelvic mechanics and discuss their rationale for ilio-sacral and/or trans-sacral screw fixation.

Modified Lumbopelvic Technique Using S1 Pedicle Screws for Spinopelvic Dissociation U-Type and H-Type Sacral Fractures With Kyphotic Deformity

Spinopelvic dissociation injuries are complex injuries defined as discontinuity between the appendicular and axial skeleton. Fracture patterns are variable, but U-type and H-type fractures are common and often present with kyphotic deformity along with translational displacement and impaction. The ideal method of fixation has not been established for these injuries. The goals of treatment include restoration of alignment, stability, and neural decompression as needed. Traditional methods of lumbopelvic fixation have spanned the upper sacral fracture site. Our novel modified method of lumbopelvic fixation directly instruments the S1 body. This allows for direct manipulation of the fracture which we theorize improves reduction and increases stability across the fracture. This article characterizes the injury patterns, outlines the modified technique, and reports the clinical and radiographic outcomes of our modified lumbopelvic fixation technique and construct.

The surgical treatment of unstable osteoporotic pelvic ring fractures with bilateral vertebropelvic stabilization using a less invasive technique

By immobilizing the joint partners between the lumbar spine and the pelvis, the vertical and horizontal forces on the sacrum are both transferred through the ilium caudally. Therefore persistent stress on the fracture is avoided. To ensure sufficient soft tissue coverage the pedicle screws are inserted via small incisions in the lumbar spine area and the iliac screws via slightly oblique incisions on both sides laterally of the posterior iliac spine. At the end the instrumentation is completed by connecting the lumbar longitudinal carriers with the cross connection between the two iliac screws via the pre-existing incisions. Due to this less invasive technique, disorders of wound healing can be avoided. Due to the lower Morbidity rate and its associated reduction in blood loss, there is corresponding decrease in the number of postoperative symptoms, which has a positive effect on early mobilization. None of the described patients showed neurological deficits preoperatively or postoperatively. LEVEL OF EVIDENCE: IV; Technical note, retrospective.

Traditional versus Minimally Invasive Spinopelvic Fixation for Sacral Fracture Treatment in Vertically Unstable Pelvic Fractures

Purpose: Numerous different fixation techniques are used to treat vertical shear sacral fractures. We report our experience with spinopelvic fixation using a minimally invasive technique. Methods: Thirty-eight patients with vertical pelvic and sacral fractures were treated with spinopelvic fixation (traditional open method, n = 21; minimally invasive technique, n = 17). Intergroup comparisons and statistical analysis were performed for intraoperative blood loss, operative time, post-operative radiographic grading, post-operative functional score, and complication rates. Results: Patients treated with the minimally invasive technique had a significantly shorter operative time (−52 min, p = 0.022), reduced blood loss volume (−287 mL, p < 0.001), and better cosmetic appearance (p < 0.05) than those in the traditional open group. There were no significant intergroup differences in post-operative radiographic grading (p = 0.489) or post-operative functional scores (p = 0.072). The complication rate was lower in the minimally invasive group (1/17 patients) than in the traditional open group (2/21 patients). Conclusions: Minimally invasive spinopelvic fixation is a viable treatment for sacral fractures and can reduce blood loss and operative time.

SURGICAL MANAGEMENT OF AGED COMPLEX SACRAL INJURIES BY LUMBOPELVIC STABILIZATION

ABSTRACT Objective: Evaluate the surgical indications, epidemiological data, radiographic outcomes, and postoperative complications of 16 cases of aged complex sacral fractures treated using bilateral spinopelvic fixation (PEF) or triangular osteosynthesis (OT) techniques in a case referral service. Traumatology and orthopedics complexes. Methods: A longitudinal study based on a retrospective review of patients’ medical records with complex sacral fractures admitted between 2014 and 2020. All patients over 18 years of age whose time of evolution between the trauma and the surgical procedure was greater than or equal to three weeks were included. Results: The mean age was 39.8 years (18 to 71). Anterior pelvic ring injuries represented the most common association, present in 12 (75%) cases. In 8 (50%) cases, there was no neurological injury, 1 (6.2%) individual evolved with paresthesia, 2 (12.5%) with paresis in the lower limbs, and 5 (31.3%) with sphincter dysfunctions. Among the patients with neurological impairment, 4 (50%) evolved with complete improvement, 2 (25%) showed partial improvement, and 2 (25%) cases remained with the deficit. The mean surgical time was 3.6 hours for OT and 4.9 hours for FEP. Postoperative complications occurred in 4 (44.4%) patients who underwent PEF, and there were no postoperative complications in the OT group. Conclusions: The surgical management of these lesions using OT and FEP proved safe and effective. The minimum follow-up was 12 months, and all the individuals analyzed showed good evolution. Level of evidence IV; case series.

The Effects of Different Screw Combinations on the Initial Stability of Ankle Arthrodesis

BACKGROUND

The literature is scanty regarding the biomechanical effects of different thread configurations on the initial stability of ankle arthrodesis. This study aims to compare the initial stability of tibiotalar fusion site in ankle arthrodesis using cannulated screws with different thread designs.

METHODS

We biomechanically tested under cyclic loading the effects of different screw combinations on the initial stability of ankle arthrodesis. A total of 28 synthetic ankle models were divided into four groups: two partially threaded cancellous screws (group A), partially and fully threaded cancellous screws (group B), a partially threaded cancellous screw with a headless compression screw (group C), and a fully threaded cancellous screw and a headless compression screw (group D). Biomechanical variables including ultimate failure load, initial stiffness, ultimate stiffness, and failure angulation were analyzed.

RESULTS

There were no differences in any of the biomechanical variables among the four groups (P = .41 for ultimate failure load, P = .079 for initial stiffness, P = .084 for ultimate stiffness, and P = .937 for failure angulation).

CONCLUSIONS

Combinations of different cannulated screws showed similar results in terms of the stability and stiffness of the tibiotalar fusion site.

Clinical and Patient-Related Outcome After Stabilization of Dorsal Pelvic Ring Fractures: A Retrospective Study Comparing Transiliac Fixator (TIFI) and Spinopelvic Fixation (SPF)

Purpose: Aim of this retrospective cohort study was the comparison of the transiliac fixator (TIFI) and spinopelvic fixation (SPF) for fixation of dorsal pelvic ring fractures in terms of clinical outcome, complications, and quality of life. Methods: Thirty-eight patients (23 men, 15 women; mean age 47 ± 19 years) with dorsal pelvic ring fractures (type-C-injuries after AO/OTA) that have been stabilized by either TIFI (group TIFI, n = 22) or SPF (group SPF, n = 16) between May 2015 and December 2018 were retrospectively reviewed. Outcome measurements included demographic data, perioperative parameters, and complications and were obtained from the medical information system. Quality of life was assessed using the German version of the short form 36 (SF-36) and short muskuloskeletal function assessment (SMFA-D). Clinical results were assessed using Merle d'Aubigné-Score, Iowa Pelvic Score, and Majeed Pelvic Score. Results: Both groups show relatively good post-operative results, which has previously been reported. Quality of life was comparable in both groups. Group TIFI was slightly superior regarding complication rates, cutting/suture time, and fluoroscopy time. Group SPF seemed to be superior regarding pain and pelvic scores. Conclusion: None of the methods could demonstrate significant superiority over the other. Management of pelvic injuries remains a highly individual challenge adapted to the individual patients' condition. Nevertheless, if fractures allow for stabilization with TIFI, the use of this method should be taken into consideration as a less invasive and more tissue-conserving approach.

Applicable safety analysis and biomechanical study of iliosacral triangular osteosynthesis

BACKGROUND

The aim of this study was to investigate the applicable safety and biomechanical stability of iliosacral triangular osteosynthesis (ITO) through 3D modeling and finite element (FE) analysis.

METHODS

Pelvic CT imaging data from 100 cases were imported into Mimics software for the construction of 3D pelvic models. The S2-alar-iliac (S2AI) screws and S2 sacroiliac screws were placed in the S2 segment with optimal distribution and their compatibility rate on the S2 safe channel was observed and analyzed. In the FE model, the posterior pelvic ring was fixed with two transsacral screws (TTS), triangular osteosynthesis (TO) and ITO, respectively. Four different loading methods were implemented in sequence to simulate the force in standing, flexion, right bending, and left twisting, respectively. The relative displacement and change in relative displacement of the three fixing methods were recorded and analyzed.

RESULTS

The theoretical compatibility rate of S2AI screw and S2 sacroiliac screw in S2 segment was 94%, of which 100% were in males and 88% in females. In the FE model, in terms of overall relative displacement, TTS group showed the smallest relative displacement, the ITO group showed the second smallest, and the TO group the largest relative displacement. The change in relative displacement of the TTS group displayed the smaller fluctuations in motion. The change in relative displacement of the TO group under right bending and left twisting displayed larger fluctuations, while the ITO group under flexion displayed larger fluctuations.

CONCLUSIONS

The simultaneous placement of S2AI screw and S2 sacroiliac screw in the S2 segment is theoretically safe. Although the biomechanical stability of ITO is slightly lower than TTS, it is better than TO, and can be used as a new method for the treatment of posterior pelvic ring injuries.

One sacroiliac screw for posterior ring fixation in unstable pelvic fractures

Unstable pelvic injuries are considered uncommon and they are usually associated with high rate of morbidity and mortality. High energy blunt trauma and falling from height are usually the main mechanism of injury. It is a retrospective study that was performed in academic level I trauma center. From September 2015 to December 2019, a consecutive series of 26 patients (7 females), with average age of 32 years with unstable pelvic fracture were included in this study. All patients underwent reduction and percutaneous fixation with one sacroiliac screw posteriorly for each sacroiliac joint and anterior arch fixation of the pelvic ring with either platting or external fixator. The average duration of follow up was 36 months. Clinical results: at the final follow-up, all patients had complete radiological healing of the fractures. The subjective functional assessment yielded excellent for twenty-two patients, good for two patients and fair for two patients. Posterior arch fixation of the pelvic ring with one sacroiliac screw beside anterior arch fixation in unstable fracture pelvis is a sufficient fixation method to maintain the requiring stability to allow complete union of the fracture. Level of Evidence: Therapeutic Level III.

Instability of the posterior pelvic ring: introduction of innovative implants

BACKGROUND

Increasing numbers of posterior pelvic ring fractures, especially in elderly patients, demonstrate the need for soft tissue protecting surgical techniques. Standard of care is iliosacral screw osteosynthesis. This type of osteosynthesis has its limitations especially in patients with reduced bone properties. Therefore, the development of new and straightforward surgical techniques and implant designs is favorable.

METHODS

Introducing this modular system for the posterior pelvic ring, known complications of iliosacral screw osteosynthesis, such as implant loosening and malpositioning may be reduced, due to innovative mechanical characteristics.

RESULTS

The shown cases demonstrate the potential benefits of the system with a wide range of treatment options due to its modularity.

CONCLUSION

The modular implant system presented here can significantly facilitate and improve the stabilization of posterior pelvic ring instabilities.

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.

Minimally invasive triangular lumboiliac and iliosacral fixation of posterior pelvic ring injuries with vertical instability: Technical note

To date, no strong consensus exists on the best way to treat posterior pelvic ring injuries when there is no neurological deficit. Various fixation methods have been described; more recently, constructs that combine lumboiliac and iliosacral fixation have been introduced. This type of fixation is mainly indicated in cases of spinopelvic dissociation with large displacement of fracture fragments in the sagittal plane. However, these techniques are associated with postoperative complications, particularly infections and severe skin complications. This led us to propose a minimally invasive lumboiliac and iliosacral fixation technique for posterior pelvic ring injuries. The procedure is done with the patient prone. It consists of pedicle screw insertion into L4 or L5 and screw fixation of the ilium with fluoroscopy guidance; intraoperative distraction can be done depending on the amount of displacement. An iliosacral screw is then inserted percutaneously to allow reduction in the transverse plane and yield a triangular construct. In the five patients that we have operated using this technique, the mean preoperative vertical displacement was 11.9±6.9mm (SD) (min 1.3, max 19.7) versus 3.7±3.2mm (min 0.3, max 6.7) postoperatively and the mean preoperative frontal displacement was 7.5±3.7mm (min 4.2, max 12.4) versus 2.5±2.0mm (min 0.3, max 4.3) postoperatively. Minimally invasive iliosacral and lumboiliac fixation is an option for treating posterior pelvic ring fractures free of neurological deficit and especially spinopelvic dissociation.

Team Approach: Spinopelvic Dissociation

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Spinopelvic dissociation is a complex and variable injury pattern that requires an integrated, multidisciplinary team including orthopaedic trauma and spine surgeons.

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Protocols and efficient channels of communication should be in place at tertiary Level-I trauma centers to ensure appropriate and timely treatment of patients with spinopelvic dissociation.

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Patients with spinopelvic dissociation may present with acute neurological deficits and impending cauda equina syndrome, necessitating urgent, coordinated care.

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Lumbopelvic fixation with sacroiliac screws yields a stable, multiplanar construct that connects the spine to the pelvis and allows for early mobilization.

Minimally invasive lumbopelvic stabilization of sacral fragility fractures in immobilized geriatric patients: feasibility and early return to mobility

INTRODUCTION

In an aging society, the incidence of sacral fragility fractures is increasing and diagnosis is often delayed. Immobilization has devastating consequences especially in elderly patients. Short-term mobilization of these patients is crucial. The aim of this study is to evaluate the early return to mobility of immobilized geriatric patients with sacral fragility fractures treated with minimally invasive lumbopelvic stabilization.

METHODS

Retrospective analysis of thirteen consecutive patients (13 females) which could not be mobilized with conservative treatment, and thus were treated with minimally invasive lumbopelvic stabilization. Pain intensity measurement on an 11-point Numeric Rating Scale (NRS), Tinetti Mobility Test (TMT), and Timed Up and Go Test (TUGT) were performed preoperatively and 4 weeks postoperatively. Surgical and medical complications were analyzed.

RESULTS

Mean age at surgery was 83.92 ± 6.27 years and mean ASA score was 2.77 ± 0.42. NRS improved from a mean of 7.18 ± 0.98 preoperatively to a mean of 2.45 ± 0.93 4 weeks postoperatively (Ρ < 0.001). TMT score improved from a mean of 4.15 ± 3.67 preoperatively to a mean of 16.39 ± 4.61 4 weeks postoperatively (Ρ < 0.001). Due to immobilization, patients were not able finish TUGT preoperatively. Four weeks postoperatively TUGT reached a mean of 31.1 ± 11.08 s. There were two surgical complications (one wound healing disorder, one rod dislocation) in two patients that required revision surgery. Two patients developed pneumonia postoperatively.

CONCLUSIONS

Minimally invasive lumbopelvic stabilization of sacral fragility fractures is feasible in geriatric patients. Early mobilization of these patients is possible after surgery. The rate of complications is acceptable.

Fixation Strength of Modified Iliac Screw Trajectory Compared to Traditional Iliac and S2 Alar-Iliac Trajectories: A Cadaveric Study

OBJECTIVE

Traditional iliac (TI) screws require extensive dissection, involve offset-connectors, and have prominent screw heads that may cause patient discomfort. S2 alar-iliac (S2AI) screws require less dissection, do not need offset connectors, and are less prominent. However, the biomechanical consequences of S2AI screws crossing the alar-iliac joint is unknown. The present study investigates the fixation strength of a modified iliac (MI) screw, which has a more medial entry point and reduced screw prominence, but does not cross the alar-iliac joint.

METHODS

Eighteen sacropelvic spines were divided into 3 groups (n = 6): TI, S2AI, and MI. Each specimen was fixed unilaterally with S1 pedicle screws and pelvic fixation according to its group. Screws were loaded at ±10 Nm at 3Hz for 1000 cycles. Motion of each screw and rod strain above and below the S1 screw was measured.

RESULTS

Toggle of the S1 screw was lowest for the TI group, followed by the MI and S2AI groups, but there were no significant differences (P = 0.421). Toggle of the iliac screw relative to the pelvis was also lowest for the TI group, followed by the MI group, and was greatest for the S2AI group, without significant differences (P = 0.179). Rod strain was similar across all groups.

CONCLUSIONS

No statistically significant differences were found between the TI, S2AI, and MI techniques with regard to screw toggle or rod strain. Advantages of the MI screw include its lower profile and a medialized starting point eliminating the need for offset-connectors.

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.

Biomechanical models of in vitro constructs for spinopelvic osteosynthesis

Spinopelvic lesions are the result of high-energy vertical trauma with axial skeletal overload where the spine impacts onto the sacrum, dissociating the lumbar spine from the pelvis. Therefore, lumbopelvic instrumentations are aimed to counteract these vertical forces, although various biomechanical aspects of the combinations of different constructs (with or without iliosacral screws) or the number of lumbar fixation levels (L5 or the combination of L5 with L4) are subject to controversy. The number of patients in each published series is too short, and the nature of the fixation is very different from one article to another, making comparison very difficult. In this paper the methodology for laboratory studies is discussed. The design of the test bench fixture, biomechanical testing protocol and data analysis are very important when inference to the clinical setting is desired.

[Closed reduction and minimally invasive fixation of a sacral avulsion fracture : Minimal invasiveness with maximum stability]

Surgical stabilization of high-energy sacral avulsion fractures with spinopelvic dissociation places high demands on the surgeon. The goal is to achieve maximum stability while minimizing invasiveness. The present case of a dislocated U‑type fracture in a 25-year-old motocross rider exemplifies how a reduction with the targeted application of closed reduction techniques through hyperextension of the hip joints and lordosis in the lumbosacral hinge and through a standardized procedure in intraoperative fluoroscopic imaging, a minimally invasive stabilization by means of transsacral screw fixation and spinopelvic fixation of lumbar vertebra 5 to the ilium in the sense of a bilateral triangular stabilization is possible without compromising the achieved stability of the osteosynthesis. The limitations of the described approach are also pointed out.

Role of triangular osteosynthesis in vertically unstable transforaminal sacrum fractures: clinical and radiological outcomes

PURPOSE

We aim to report clinical and radiological results of triangular osteosynthesis for a homogenous group of vertically unstable transforaminal sacral fractures.

METHODS

Between 2013 and 2018, 22 consecutive patients with unstable sacral fractures were treated with triangular osteosynthesis consisting of iliosacral screw augmented by spinopelvic fixation. Patients were followed up prospectively as a single cohort. Bone union, complications, clinical and radiological outcomes were investigated.

RESULTS

Mean follow-up was 3.1 years (12-76 months). There was one bilateral fracture. Two patients underwent anterior plating for pubic symphyseal disruption. Based on Majeed and Iowa pelvic scores, 13 patients had excellent, seven had good and two had fair clinical outcome. All the patients could perform squatting, sitting cross-legged and kneeling without any restrictions. There were no additional neurological injuries. One patient had non-union of sacral fracture, one patient had deep infection, one patient had marginal wound necrosis and two patients complained of pain related to implant prominence. Two patients had connecting rod backout. All but one patient attained pre-operative work status.

CONCLUSION

Triangular osteosynthesis is a reliable procedure in treating unstable transforaminal sacral fractures. It permits early weight-bearing and facilitates faster functional recovery. Careful attention to details such as sacral dysmorphism, soft tissue injury, implant placement and anterior pelvic injury helps in keeping complications to an acceptable rate.

A Modified Triangular Osteosynthesis Protocol for the Rod and Pedicle Screw Fixation of Vertical Unstable Sacral Fractures

BACKGROUND

The stabilization of vertical unstable sacral fractures has been a complex problem that is a challenge to current standard approaches. Here, we attempted to evaluate a modified technique for sacral fractures.

METHODS

In the modified triangular osteosynthesis technique, we adopted a vertical and transverse fixation with a rod and pedicle screw system to reduce and fix sacral fractures in 28 subjects. The postsurgery effect of this technique was evaluated by physical examination and radiography.

RESULTS

In the postoperative day 1, the patients were able to move body position passively from the lateral side to supine and exercise their legs by themselves. After a follow up of 20 months, radiological evaluation showed that fracture fragment reduction was excellent in 18 (64%), good (displacement 5-10 mm) in 8 (29%), and fair (displacement 10-15 mm) in 2 (7%) patients. Three patients with a preoperative perineal neurological impairment had a complete recovery after surgical decompression. All patients had achieved bone union of fractures, and no loss of fracture reduction was detected.

CONCLUSIONS

The modified procedures offered an easier approach to fix vertical unstable sacral fractures, thereby achieving quicker and stable functionality. This suggests an alternative approach to manage unstable sacral fractures.

LEVEL OF EVIDENCE

4.

CLINICAL RELEVANCE

The stabilization of vertical unstable sacral fractures has been a complex problem that is a challenge to current standard approaches. We attempted to introduce a modified technique for sacral fractures.

Bilateral vertical shear sacroiliac joint dislocations treated with bilateral triangular osteosynthesis in a young female: A case report

Case

Type C pelvic ring fractures account for only 0.34% of all pelvic fractures (Zhang, 2012 [1]). Anterior and posterior pelvic fixation is necessary in these injuries and can be accomplished using a variety of techniques. This study presents a case of bilateral vertical shear sacroiliac joint dislocations with an associated hip dislocation and pubic rami fractures that was treated with bilateral triangular osteosynthesis and INFIX.

Conclusion

This is the first reported case of bilateral vertical shear sacroiliac joint dislocation treated with triangular osteosynthesis. Anterior pelvic fixation with INFIX and posterior fixation with lumbopelvic and percutaneous sacroiliac screws resulted in excellent radiographic and clinical outcomes.

Single column plate plus other column lag screw fixation vs. both column plate fixation for anterior column with posterior hemitransverse acetabular fractures - a biomechanical analysis using different loading protocols

OBJECTIVES

Open reduction and internal fixation of both columns is considered the treatment of choice for displaced anterior column with posterior hemitransverse (ACPHT) fractures in non-geriatric patients. Plate fixation of one column combined with lag screw fixation of the other column allows to decrease operative time and approach-related morbidity compared to conventional both column plating. The aim of this biomechanical study was to evaluate whether single column plate plus other column lag screw fixation confers similar stability to both column plate fixation. Physiological loads were simulated using both the single-leg stance (SLS) as well as the sit-to-stand (STS) loading protocols.

METHODS

A clinically relevant ACPHT fracture model was created using fourth-generation composite hemipelves. Fractures were stabilized with three different fixation constructs: (1) anterior column plate plus posterior column screw fixation (AP+PCS), posterior column plate plus anterior column screw fixation (PP+ACS) and anterior column plate plus posterior column plate fixation (AP+PP). Specimens were loaded from 50 to 750 N with a ramp of 100 N/s. Fracture gap motion (FGM) and relative interfragmentary rotation (RIFR) between the three main fracture fragments were assessed under loads of 750 N using an optical 3D measurement system.

RESULTS

STS loading generally resulted in higher mean FGM and RIFR than STS loading in the AP+PCS and AP+PP groups, while no significant differences were found in the PP+ACS group. Compared to conventional both column plate fixation (AP+PP), PP+ACS displayed significantly higher FGM and RIFR between the iliac wing and the posterior column during SLS loading. No significant differences in FGM and RIFR were identified between the AP+PCS and the AP+PP group.

CONCLUSION

Overall, single column plate plus other column lag screw fixation conferred similar stability to conventional both column plate fixation. From a clinical point of view, AP+PCS appears to be the most attractive alternative to conventional AP+PP for internal fixation of ACPHT fractures.