Is cannulated-screw fixation an alternative to plate osteosynthesis in open book fractures? A biomechanical analysis

Minimally Invasive Treatment of Pelvic Fractures with Titanium Elastic Nailing: An Innovative Technology

BACKGROUND

Minimally invasive treatment has become the most popular and effective treatment for pelvic fractures. This study aimed to evaluate the safety and efficacy of a new technique, titanium elastic nailing (TEN), for the minimally invasive treatment of pelvic fractures.

METHOD

Twenty-four patients with pelvic fractures were referred to us between January 2020 to January 2022, including sixteen males and 8 females. Pelvic fractures were temporarily fixed by pelvic fixation belt accompanied by traction from the lower limb bone. Anterior pelvic ring injuries (superior ramus of pubis) and ilium fractures were treated with closed reduction and intramedullary fixation with minimally invasive TEN. Intraoperative C-arm, including pelvic anteroposterior, pelvic outlet, inlet and ilium oblique views, and O-arm fluoroscopy (intraoperative CT) were employed to assess fractures reduction and determine the location of the elastic titanium nail within the bone channel.

RESULTS

By adopting closed reduction and minimally invasive incision techniques, pelvic fractures could be safely fixed by placing an elastic titanium nail in the osseous medullary cavity channels of the pelvis. Postoperative investigation indicated that the wounds of all patients were healed in the first stage without any occurrence of complications, such as injuries to the nerves, blood vessels, and important tissue structures. Patients are essential quickly after the operation and could perform the functional exercise in the early stages of the recovery.

CONCLUSION

TEN can be used for minimally invasive treatment of pelvic fractures. This novel technique has no obvious complications and is worthwhile in clinical practice.

Does a novel 3D printed individualized guiding template based on cutaneous fiducial markers contribute to accurate percutaneous insertion of pelvic screws? A preliminary phantom and cadaver study

BACKGROUND

Most 3D-printed guiding templates require dissection of soft tissues to match the corresponding surfaces of the guiding templates. This study sought to explore the accuracy and acceptability of the novel 3D printed individualized guiding templates based on cutaneous fiducial markers in minimally invasive screw placement for pelvic fractures.

METHODS

The printed template was tested on five high-fidelity biomimetic phantom models of the bony pelvis and its surrounding soft tissues as well as on two fresh frozen cadavers. Four cutaneous fiducial markers were transfixed on each phantom model prior to performing CT scans to reconstruct their 3D models. Personalized templates for guiding screw insertion were designed based on the positions of the fiducial markers and virtually planned target screw channels after scanning, followed by 3D printing of the guide. Phase 1 consisted of five expert surgeons inserting one anterograde supra-pubic screw and one sacroiliac screw percutaneously into each phantom model using the 3D-printed guide. The deviation of screw positions between the pre-operative planned and post-operative actual ones was measured after registering their 3D modelling. A Likert scale questionnaire was completed by the expert surgeons to assess their satisfaction and acceptability with the guiding template. Phase 2 consisted of repeating the same procedures on the fresh frozen cadavers in order to demonstrate face, content and concurrent validity.

RESULTS

In Phase 1, all ten screws were successfully implanted with the assistance of the guiding template. Postoperative CT scans confirmed that all screws were safely positioned within the bony pelvic channels without breaching the far cortex. The mean longitudinal deviation at the bony entry point and screw tip between the pre-operative planned and post-operative actual screw paths were 2.83 ± 0.60 mm and 3.12 ± 0.81 mm respectively, with a mean angular deviation of 1.25 ± 0.41°. Results from the Likert questionnaire indicated a high level of satisfaction for using the guiding template among surgeons. In Phase 2, results were similar to those in Phase 1.

CONCLUSIONS

The 3D-printed guiding template based on cutaneous fiducial markers shows potential for assisting in the accurate insertion of percutaneous screws in the pelvis.

A novel minimally invasive and press-fit method for symphysiodesis - a biomechanical analysis

PURPOSE

Does the cylindrical shaped bone block allow a stable construct for the arthrodesis of the pubic symphysis compared to a rectangular shaped bone block. The cylindrical shaped bone block stabilized by a 3.5 symphyseal plate is inferior to the stabilization with an internal fixator.

METHODS

This study analyzed the arthrodesis of the pubic symphysis on 24 synthetic pelvises, using a rectangular shaped bone block (control group) or a cylindrical shaped bone block, stabilized with a symphysis locking plate (n = 8) as the standard clinical procedure. Additionally we analyzed the stability using an internal fixator.

RESULTS

This study showed that utilizing a cylindrical shaped synthetic bone graft results in a significant higher contact area and compression force compared to the classical rectangular shaped graft. Furthermore, the stabilization with an internal fixator had the tendency for increases of compression force and contact area, yet without a statistical significance, when compared to the plate fixation.

CONCLUSION

The novel method of cylindrical symphysis resection and cylindrical bone block implantation allowed an increased biomechanical stability compared to using a classical rectangular bone graft, also resulting in higher contact area. Moreover, this technique would also allow a minimally invasive approach for this purpose, which in turn could preserve perisymphyseal ligaments, thereby improving healing in a clinical context.

Percutaneous Fixation for Traumatic Symphysis Pubis Disruption-Are the Results Superior Compared to Open Techniques? A Systematic Review and Meta-Analysis of Clinical and Biomechanical Outcomes

INTRODUCTION

Open reduction and reconstruction plate and screws fixation (RPSF) is considered the gold standard for the treatment of traumatic symphysis pubis diastasis (SPD). Percutaneous cannulated screw fixation (PCSF) has recently gained popularity as it may reduce operative time and morbidity. The current systematic review aims to compare the clinical and radiological outcomes of PCSF and RPSF in traumatic SPD and analyze the biomechanical effectiveness of PCSF.

MATERIAL AND METHODS

The Medline, Scopus, and Cochrane databases were searched until February 2023. The primary outcomes were the incidence of implant failure and revision surgery and the amount of displacement of symphysis pubis. Secondary outcomes were the intraoperative blood loss, the scar length, the operative time, the wound infection, and the patients' functional improvement.

RESULTS

Six clinical trial studies with a total of 184 patients and nine biomechanical studies were included. There was no significant difference between the two groups regarding the incidence of implant failure, the prevalence of revision surgery, and the amount of postoperative loss of reduction (p > 0.05 for all outcomes). The intraoperative blood loss (14.9 ± 4.2 mL for PCSF versus 162.7 ± 47.6 mL for PCSF, p < 0.001) and the incision length (1.7 ± 0.9 mL for PCSF versus 8 ± 1.4 mL for PCSF, p < 0.001) were significantly lower after PCSF. The mean operative time was 37 ± 19.1 min for PCSF and 68.9 ± 13.6 min for RPSF (p < 0.001). The infection rate was less frequent in the PCSF group (3% for PCSF versus 14.3% for RPSF, p = 0.01). One clinical trial reported better functional recovery after PCSF. In all biomechanical studies, the threshold for implant failure was beyond the applied forces corresponding to daily activities.

CONCLUSIONS

PCSF for traumatic SPD is associated with less operative time, less blood loss, and a lower infection rate when compared to conventional plate techniques without increasing the incidence of postoperative fixation failure and revision surgery. Moreover, PCSF has been proven to be biomechanically sufficient for stabilization. Therefore, it should be considered an efficient and viable alternative for the reconstruction of SPD when closed reduction can be adequately achieved.

Percutaneous screw fixation of the pubic symphysis versus plate osteosynthesis: a biomechanical study

Objectives: To compare the stability of screw fixation with that of plate fixation for symphyseal injuries in a vertically unstable pelvic injury (AO/Tile 61-C1) associated with complete disruption of the sacroiliac joint and the pubic symphysis. Methods: Eight fourth-generation composite pelvis models with sacroiliac and pubic symphyseal disruption (Sawbones, Vashon Island, WA) underwent biomechanical testing simulating static single-leg stance. Four were fixed anteriorly with a symphyseal screw, and 4 with a symphyseal plate. All had single transsacral screw fixation posteriorly. Displacement and rotation were monitored at both sacroiliac joint and pubic symphysis. Results: There was no significant difference between the 2 groups for mean maximum force generated. There was no significant difference in net displacement at both sacroiliac joint and pubic symphysis. There was significantly less rotation but more displacement in the screw group in the Z-axis. The screw group showed increased stiffness compared with the plate group. Conclusions: This is the first biomechanical study to compare screw versus plate symphyseal fixation in a Tile C model. Our biomechanical model using anterior and posterior fixation demonstrates that symphyseal screws may be a viable alternative to classically described symphyseal plating.

Percutaneous screw fixation of pubic symphysis disruption: A preliminary report

BACKGROUND

Percutaneous techniques are commonly used to treat pelvic ring disruptions but are not mainstream for fixation of pubic symphysis disruption worldwide. Potential advantages include less blood loss and lower risk of surgical site infection, especially in the morbidly obese or multiply injured patient. This study was performed to describe the clinical and radiographic outcomes of patients after percutaneous reduction and screw fixation of pubic symphysis disruption and to evaluate the preliminary safety and efficacy of this technique and its appropriateness for further study as an alternative method of fixation.

METHODS

A retrospective review was performed to identify all patients who underwent percutaneous fixation of pubic symphysis disruption by two surgeons at an academic Level I trauma center over a 3-year period. Patients underwent percutaneous reduction and fixation of the pubic symphysis using 1 or 2 fully or partially threaded 5.5, 6.5, or 7.3 mm cannulated screws in a transverse or oblique configuration. Associated posterior ring injuries were fixed with trans-sacral and/or iliosacral screws. The primary outcome of interest was loss of reduction, defined as symphysis distance greater than 15 mm measured on final AP pelvis radiograph. Secondary outcomes collected by chart review were operative time, blood loss, vascular or urologic injury, sexual dysfunction, infection, implant loosening or breakage, and revision surgery.

RESULTS

Twelve patients met criteria and primary and secondary outcomes were collected. Mean clinical and radiographic follow-up were 15 months each. One patient lost reduction. Mean operative time and blood loss were 124 min and 29 cc, respectively. No vascular or urologic injuries occurred. Two patients reported sexual dysfunction. No patients became infected or required revision surgery. Four patients underwent implant removal. Seventeen additional patients were excluded due to short follow-up and limited outcomes were collected. Two of these patients lost reduction. Three underwent implant removal.

CONCLUSION

These data support percutaneous reduction and screw fixation of pubic symphysis disruption as a potentially safe and effective method of treatment that warrants further investigation.

A novel Patient-Specific Three-Dimensional Printing Template Based on External Fixation for Pelvic Screw Insertion

PURPOSE

To investigate the clinical effect of novel patient-specific 3D printing templates based on external fixation for pelvic screw insertion compared with the fluoro-navigation technique.

MATERIALS AND METHODS

We retrospectively studied 18 pelvic fracture patients from July 2017 to July 2018. For analysis, patients were divided into two groups: the template group (15 screws in 8 patients) and the fluoro-navigation group (22 screws in 10 patients). The screw insertion time, radiation exposure time, and accuracy of the screw insertion as evaluated by postoperative CT scans were analyzed.

RESULTS

In the template group, the average screw insertion time (11.5 ± 2.3 min/screw) was significantly 50.6% less than that in the fluoro-navigation group (23.3 ± 3.1 min/screw; P < 0.05). The average time of X-ray exposure in the template group (11.5 ± 3.9 s/screw) was also significantly 39.8% less than in the fluoro-navigation group (19.1 ± 2.5 s/screw; P < 0.05). In the template group, the mean deviation distance and angle between the actual and planned screw position was 2.6 ± 0.2 mm and 2 ± 0.3°.

CONCLUSIONS

The patient-specific template based on external fixation can guide the insertion of the pelvic screw accurately and safely while significantly reducing operation and radiation exposure time.

Symphyseal plate with trans-symphyseal cross-screws for fixation of tile-type B1 pelvic ring injuries: radiological and functional evaluation

INTRODUCTION

Failure to neutralize the different physiological forces acting on the inferior as well as the superior regions of the pubic symphysis, the long healing time, is blamed for the repeated failures of conventional superior symphyseal plating.

MATERIAL AND METHODS

A three years prospective case series study between January 2017 and December 2019 was done, to evaluate the radiological and the functional outcomes, using Matta/Tornetta and Majeed criteria respectively, of the combination of trans-symphyseal cross-screws configuration and superior symphyseal plate in Tile-type B1 pelvic injuries.

RESULTS

Thirty patients, 18 with anteroposterior compression type II and 12 with type III, with a mean follow-up of 20 months ±5 were included. Radiologically, 26 (86.6%) cases showed an excellent, one (3.3%) good and three (10%) fair outcome. Clinically, excellent outcome in 26 (86.6%) cases, good in two (6.6%) cases, and fair in two (6.6%). Intra-operative drill bit breakage occurred in three (10%) cases and was the only reported technical complication. Significant re-displacement was reported in three (10%) cases.

CONCLUSION

The open trans-symphyseal cross-screws for fixation of the superior symphyseal plate is a simple, efficient, and safe technique with the biomechanical advantages of an extra-fixation point to the inferior symphysis together with a long and a strong bony anchorage.

A novel internal fixation method for open book injuries of the pubic symphysis- A biomechanical analysis

BACKGROUND

Pelvic fractures in adults are common injuries and account for up to 3.64% of all fractures. Usually, the treatment of open book injuries (Types B1.1 and B1.2 AO-Classification) is open reduction and plate stabilization using dynamic compression plates, with or without interlocking screws. These implants seem to enhance the outcome of such injuries, but also variety of complications occurs. To reduce complications and achieve appropriate reduction and stabilization, this study compared established stabilization techniques to a novel minimally invasive internal fixation method using an internal fixator system that is already being utilized for spinal fractures.

METHODS

This study was performed on 32 composite pelvises in a bilateral stance biomechanical model. The pelvises were variously stabilized with an internal fixator, a 4.5 mm dynamic compression plate and a 3.5 mm symphyseal locking dynamic compression plate. The contact area and loading forces were assessed by a sensor film inside the symphyseal gap.

FINDINGS

This study showed significantly greater reduction and loading capabilities of the internal fixator compared to the other implants (p < 0.05). There was also significantly greater contact area with the use of an internal fixator compared to the other implants (p < 0.05). The 3.5 mm interlocking plate showed significantly greater contact area compared to the 4.5 mm plate (p < 0.05).

INTERPRETATION

The internal fixator that is already proven in spinal surgery is biomechanically superior to conventional implants used in pelvic surgery. The contact area analysis furthermore showed a more physiological loading pattern, which can improve ligamentous healing in a clinical context.

Stabilization of a Type B1.1 Injury in a Morbidly Obese Patient Using an Internal Fixator in a Minimally Invasive Technique: A Case Report

CASE

In this case report, we present a novel stabilization technique of the pubic symphysis using an internal spinal fixator in a 78-year-old morbidly obese woman having a pelvic disruption type B1.1 (AO classification). We treated the disruption using an internal fixator to reduce the extent of the incision and soft-tissue damage.

CONCLUSIONS

The use of an internal fixator, known from percutaneous spinal fixation, for the stabilization of the pubic symphysis in cases of disruption ("open book" injuries) may be an alternative to the standard plate fixation as a novel minimally invasive stabilization technique.

A novel percutaneous crossed screws fixation in treatment of Day type II crescent fracture-dislocation: A finite element analysis

Objective

Day type II crescent fracture–dislocation is a subtype of pelvic lateral compression injury. At present, there is still a controversy on the operative approach and fixation technique. We have put forward closed reduction and percutaneous crossed screws fixation for treating type-II crescent fracture–dislocation. Finite element analysis is used to compare the biomechanical properties between percutaneous crossed screws and other internal fixations.

Methods

A three-dimensional finite element model of Day type-II crescent fracture–dislocation was simulated using 5 implants, including double anterior plates (Model A), one posterior plate and one iliac screw (Model B), one sacroiliac joint screw (Model C), crossed one iliac screw and one sacroiliac joint screw (Model D), and crossed two iliac screws and one sacroiliac joint screw (Model E). 600-N stress was applied to S1 vertebral end-plate. To evaluate the biomechanical properties, the stress distribution and displacement distribution of the pelvis, stress distribution of the crescent fragment and stress distribution of plate and cannulated screw were recorded and analyzed.

Results

Under the loading of 600N, the maximum pelvic displacements in the finite element model were compared as follows: model E (0.070 ​mm), model D (0.071 ​mm), model A (0.080 ​mm), model C (0.096 ​mm), and model B (0.112 ​mm). The maximum displacements of crescent fragment were compared as follows: model E (0.018 ​mm), model B (0.022 ​mm), model D (0.023 ​mm), model A (0.030 ​mm), and model C (0.043 ​mm). The maximum stress of all implants were compared as follows: model D (90.01 ​Mpa), model E (81.60 ​Mpa), model C (69.07 ​Mpa), model A (56.51 ​Mpa), model B (18.29 ​Mpa). Model E and model D could provide better mechanical support for whole pelvic.

Conclusions

With sufficient biomechanical stability and minimally invasive advantage, percutaneous crossed screw fixation is a recommended treatment for Day Type-II Crescent Fracture–dislocation. It is recommended to fix crescent fracture fragment and sacroiliac joint simultaneously during the operation. If it is difficult to fix the both position, the sacroiliac joint is preferentially fixed.

The translational potential of this article

There is a controversy on the operative approach and fixation technique of Day type-II crescent fracture–dislocation. This article proves that percutaneous crossed screw fixation is a recommended treatment for Day type-II crescent fracture–dislocation by finite element analysis.

Physiological in vitro sacroiliac joint motion: a study on three-dimensional posterior pelvic ring kinematics

The sacroiliac joint (SIJ) is a well-known source of low back and pelvic pain, of increasing interest for both conservative and surgical treatment. Alterations in the kinematics of the pelvis have been hypothesized as a major cause of SIJ-related pain. However, definitions of both the range and the extent of physiological movement are controversial, and there are no clear baseline data for pathological alterations. The present study combined a novel biomechanical setup allowing for physiological motion of the lumbosacral transition and pelvis without restricting the SIJ movement in vitro, combined with optical image correlation. Six fresh human pelvises (81 ± 10 years, three females, three males) were tested, with bodyweight-adapted loading applied to the fifth lumbar vertebra and both acetabula. Deformation at the lumbopelvises was determined computationally from three-dimensional image correlation data. Sacroiliac joint motion under the loading of 100% bodyweight primarily consisted of a z-axis rotation (0.16°) and an inferior translation of the sacrum relative to the ilium (0.32 mm). Sacroiliac joint flexion-extension rotations were minute (< 0.02°). Corresponding movements of the SIJ were found at the lumbosacral transition, with an anterior translation of L5 relative to the sacrum of -0.97 mm and an inferior translation of 0.11 mm, respectively. Moreover, a flexion of 1.82° was observed at the lumbosacral transition. Within the innominate bone and at the pubic symphysis, small complementary rotations were seen around a vertical axis, accounting for -0.10° and 0.11°, respectively. Other motions were minute and accompanied by large interindividual variation. The present study provides evidence of different SIJ motions than reported previously when exerted by physiological loading. Sacroiliac joint kinematics were in the sub-degree and sub-millimeter range, in line with previous in vivo and in vitro findings, largely limited to the sagittal rotation and an inferior translation of the sacrum relative to the ilium. This given physiological loading scenario underlines the relevance of the lumbosacral transition when considering the overall motion of the lumbopelvis, and how relatively little the other segments contribute to overall motion.

A biomechanical cadaver comparison of suture button fixation to plate fixation for pubic symphysis diastasis

OBJECTIVES

To determine whether suture button fixation of the pubic symphysis is biomechanically similar to plate fixation in the treatment of partially stable pelvic ring injuries.

METHODS

Twelve pelvis specimens were harvested from fresh frozen cadavers. Dual-x-ray-absorptiometry (DXA) scans were obtained for all specimens. The pubic symphysis of each specimen was sectioned to simulate a partially stable pelvic ring injury. Six of the pelvises were instrumented using a 6 hole, 3.5 mm low profile pelvis plate and six of the pelvises were instrumented with two suture button devices. Biomechanical testing was performed on a pneumatic testing apparatus in a manner that simulates vertical stance. Displacement measurements of the superior, middle, and inferior pubic symphysis were obtained prior to loading, after an initial 440 N load, and after 30,000 and 60,000 rounds of cyclic loading. Statistical analysis was performed using Wilcoxon-Mann-Whitney tests, Fisher's exact test, and Cohen's d to calculate effect size. Significance was set at p < 0.05.

RESULTS

There was no difference between groups for DXA T scores (p = 0.749). Between group differences in clinical load to failure (p = 0.65) and ultimate load to failure (p = 0.52) were not statistically significant. For symphysis displacement, the change in fixation strength and displacement with progressive cyclic loading was not significant when comparing fixation types (superior: p = 0.174; middle: p = 0.382; inferior: p = 0.120).

CONCLUSION

Suture button fixation of the pubic symphysis is biomechanically similar to plate fixation in the management of partially stable pelvic ring injuries.

Ultrasound-guided supra-acetabular pin placement in pelvic external fixation: description of a surgical technique and results

INTRODUCTION

Pelvic fracture in trauma patients can lead to hemodynamic instability. External fixation is a treatment capable of stabilizing these injuries in the context of damage control surgery. Supra-acetabular pin offers the greater biomechanical stability but requires the use of intraoperative fluoroscopy. The aim of this study was to analyze our results for an ultrasound-guided supra-acetabular pinning.

MATERIAL AND METHODS

Cross-sectional study with cadaveric specimens. Ultrasound-guided pin placement assessed by fluoroscopy and dissection.

RESULTS

Fourteen ultrasound-guided supra-acetabular pins were placed in seven cadaveric specimens. Excellent placement in all cases, evaluated with radiological control. Good qualitative bone fixation after dissection. One femoral cutaneous nerve was not found during anatomic dissection and was assumed injured.

CONCLUSION

Ultrasound-guided supra-acetabular pin placement is a feasible and effective technique. Our study indicates that pin placement without intraoperative fluoroscopy is feasible without compromising the reliability of its placement.