Comparison of Fixation Techniques for Acetabular Fractures Involving the Anterior Column with Disruption of the Quadrilateral Plate: A Biomechanical Study

Independent volumetric internal fixation reduces posterior column acetabular fracture site motion as compared to plate/screw construct: A biomechanical analysis

Aims & objectives

To establish whether a suprapectineal pelvic reconstruction plate and posterior column screw (P&S) construct or a single 6.5-mm cannulated posterior column screw (PCS) construct demonstrates greater mechanical stability for fixation of acetabulum fractures involving the posterior column (PC). We hypothesized that the PCS construct would result in less fracture site motion.

Materials & methods

Twelve fourth-generation composite hemipelvi were utilized, 6 for each construct. The P&S construct consisted of a suprapectineal pelvic reconstruction plate with two 3.5-mm posterior column screws crossing the fracture site in lag-by-technique fashion and two screws anchoring the plate to the sciatic buttress. The PCS construct consisted of a single 6.5-mm partially threaded cannulated screw placed in an antegrade fashion. Both fixation models were cyclically loaded at 0.5 cycles/second at 400N and 800N, first in a sit-to-stand position that is expected during recovery, and subsequently in a squat-to-stand position to test overload conditions.

Results

Under sit-to-stand loading, the PCS construct resulted in less motion at the fracture site than the P&S construct (0.06 ± 0.02 mm vs 0.1 ± 0.02 mm at 400N, p = 0.02; 0.13 ± 0.03 mm vs 0.19 ± 0.04 mm at 800N, p = 0.03). The PCS construct also demonstrated less fracture site motion under squat-to-stand loading (0.22 ± 0.13 mm vs 1.9 ± 0.5 mm at 400N, p = < 0.001; 1.48 ± 0.44 mm vs 4.77 ± 0.3 mm at 800N, p = < 0.001). At 800 N, half of the repairs failed during squat-to-stand loading (2 PCS, 4 P&S).

Conclusion

Fixation of the posterior column of the acetabulum with a 6.5-mm cannulated screw demonstrated comparable fracture motion upon loading compared to the plate and screw construct.

The infraacetabular screw versus the antegrade posterior column screw in acetabulum fractures with posterior column involvement: a biomechanical comparison

INTRODUCTION

Traditionally, plate osteosynthesis of the anterior column combined with an antegrade posterior column screw is used for fixation of anterior column plus posterior hemitransverse (ACPHT) acetabulum fractures. Replacing the posterior column screw with an infraacetabular screw could improve the straightforwardness of acetabulum surgery, as it can be inserted using less invasive approaches, such as the AIP/Stoppa approach, which is a well-established standard approach. However, the biomechanical stability of a plate osteosynthesis combined with an infraacetabular screw instead of an antegrade posterior column screw is unknown.

MATERIAL AND METHODS

Two osteosynthesis constructs were compared in a synthetic hemipelvis model with an ACPHT fracture: Suprapectineal plate + antegrade posterior column screw (APCS group) vs. suprapectineal plate + infraacetabular screw (IAS group). A single-leg stance test protocol with an additional passive muscle force and a cyclic loading of 32,000 cycles with a maximum effective load of 2400 N was applied. Interfragmentary motion and rotation of the three main fracture lines were measured.

RESULTS

At the posterior hemitransverse fracture line, interfragmentary motion perpendicular to the fracture line (p < 0.001) and shear motion (p < 0.001) and at the high anterior column fracture line, interfragmentary motion longitudinal to the fracture line (p = 0.017) were significantly higher in the IAS group than in the APCS group. On the other hand, interfragmentary motion perpendicular (p = 0.004), longitudinal (p < 0.001) and horizontal to the fracture line (p = 0.004) and shear motion (p < 0.001) were significantly increased at the low anterior column fracture line in the APCS group compared to the IAS group.

CONCLUSIONS

Replacing the antegrade posterior column screw with an infraacetabular screw is not recommendable as it results in an increased interfragmentary motion, especially at the posterior hemitransverse component of an ACPHT fracture.

Anterior column acetabulum fracture fixation with a screw-augmented acetabular cup-a biomechanical feasibility study

BACKROUND

The beneficial effects of unrestricted postoperative full weight bearing for elderly patients suffering hip fractures have been demonstrated. However, there is still existing disagreement regarding acetabular fractures.The aim of this biomechanical study was to evaluate the initial load bearing capabilities of different fixation constructs of anterior column fractures (ACFs) in osteoporotic bone.

METHODS

Artificial pelvises with ACFs were assigned to three groups (n = 8) and fixed with either a 7.3 mm partially threaded antegrade cannulated screw (group AASS), an anteriorly placed 3.5 mm plate (group AAPF), or a press-fit acetabular cup with screw augmentation (group AACF). All specimens underwent ramped loading from 20 N preload to 200 N at a rate of 18 N/s, followed by progressively increasing cyclic testing at 2 Hz until failure performed at a rate of 0.05 N/cycle. Relative displacements of the bone fragments were monitored by motion tracking.

FINDINGS

Initial stiffness (N/mm) was 118.5 ± 34.3 in group AASS, 100.4 ± 57.5 in group AAPF, and 92.9 ± 44.0 in group AACF, with no significant differences between the groups, p = 0.544. Cycles to failure were significantly higher in groups AACF (8364 ± 2243) and AAPF (7827 ± 2881) compared to group AASS (4440 ± 2063), p ≤ 0.041.

INTERPRETATION

From a biomechanical perspective, the minimally invasive cup fixation with screw augmentation demonstrated comparable stability to plate osteosynthesis of ACFs in osteoporotic bone. The results of the present study do not allow to conclusively answer whether immediate full weight bearing following cup fixation shall be allowed. Given its similar performance to plate osteosynthesis, this remains rather an utopic wish and a more conservative approach deems more reasonable.

Percutaneous osteosynthesis of acetabular fractures with quadrilateral plate involvement using an infra-pectineal plate through a new paramedial approach: Description of the technique using cadaveric specimens

Percutaneous osteosynthesis of acetabular fractures with quadrilateral plate involvement using an infra-pectineal plate through a new paramedial approach using cadaveric specimens.

BACKGROUND

Intrapelvic approaches and infrapectineal plates have been used since the mid-nineties to solve Quadrilateral Plate osteosynthesis, with some problems in applying screws in the correct direction and difficulty in fracture reduction. We describe a minimally invasive paramedial approach and new ways to fix infrapectineal plates using one-step osteosynthesis (reduction and fixation).

METHODS

Four transverse and four posterior hemitransverse acetabular fractures were reproduced using four fresh frozen cadavers. Acetabular osteosynthesis was performed using the paramedial approach. Sequential lasting time and reduction/stability quality were measured using analysis of variance (ANOVA) with Bonferroni Correction as the statistical method, registering iatrogenic injuries.

RESULTS

Osteosynthesis was performed on seven acetabulae using infrapectineal horizontal plates for transverse fractures and vertical plates for posterior hemitransverse fractures. The duration of incision was 3:08 min and osteosynthesis was 55:12 min, with a total of 58:29 min. Median fracture displacement of 13.25 mm turned to a median of 0.01 mm once fracture osteosynthesis was performed with a p = 0.017. The peritoneum was injured twice and good osteosynthesis stability was observed.

CONCLUSION

The paramedial approach is safe with direct access to key anatomical structures for acetabular osteosynthesis. Infrapectineal with reverse fixation plate osteosynthesis provides an excellent reduction rate and good stability once the implants act against displacement forces, making it possible to direct them freely. Further clinical and biomechanical trials are required to confirm our findings. We believe that there was an improvement of up to 60% in the result quality for some cases; however, this technique must be compared with other techniques. Evidence Level IV (Experimental Trial).

Biomechanical study of different fixation constructs for anterior column and posterior hemi-transverse acetabular fractures: a finite element analysis

BACKGROUND

To compare the biomechanical properties and stability, using a finite element model, of four fixation constructs used for the treatment of anterior column and posterior hemi-transverse (ACPHT) acetabular fractures under two physiological loading conditions (standing and sitting).

METHODS

A finite element model simulating ACPHT acetabular fractures was created for four different scenarios: a suprapectineal plate combined with posterior column and infra-acetabular screws (SP-PS-IS); an infrapectineal plate combined with posterior column and infra-acetabular screws (IP-PS-IS); a special infrapectineal quadrilateral surface buttress plate (IQP); and a suprapectineal plate combined with a posterior column plate (SP-PP). Three-dimensional finite element stress analysis was performed on these models with a load of 700 N in standing and sitting positions. Biomechanical stress distributions and fracture displacements were analysed and compared between these fixation techniques.

RESULTS

In models simulating the standing position, high displacements and stress distributions were observed at the infra-acetabulum regions. The degree of these fracture displacements was low in the IQP (0.078 mm), as compared to either the IP-PS-IS (0.079 mm) or the SP & PP (0.413 mm) fixation constructs. However, the IP-PS-IS fixation construct had the highest effective stiffness. In models simulating the sitting position, high fracture displacements and stress distributions were observed at the regions of the anterior and posterior columns. The degree of these fracture displacements was low in the SP-PS-IS (0.101 mm), as compared to the IP-PS-IS (0.109 mm) and the SP-PP (0.196 mm) fixation constructs.

CONCLUSION

In both standing and sitting positions, the stability and stiffness index were comparable between the IQP, SP-PS-IS, and IP-PS-IS. These 3 fixation constructs had smaller fracture displacements than the SP-PP construct. The stress concentrations at the regions of quadrilateral surface and infra-acetabulum suggest that the buttressing fixation of quadrilateral plate was required for ACPHT fractures.

Three-dimensional morphological analysis of quadrilateral plate fragments in associated both-column acetabular fractures

OBJECTIVE

To investigate whether the fracture morphology of quadrilateral plate (QP) fragments is associated with the anterior and posterior columns in associated both-column (ABC) fractures.

MATERIALS AND METHODS

Three-dimensional computed tomography data of 100 ABC fractures treated at our hospital from August 2016 to August 2019 were retrospectively analyzed using Mimics and 3-matic software. The distribution of fracture lines was described using the fracture mapping technique.

RESULTS

One fragment presented on the QP was confirmed in 88% of the patients. The QP fragments' fracture lines were divided into the anterior oblique (AO), superior posterior oblique (SPO), and mid-posterior oblique (MPO) lines, occurring in 100, 86, and 8 cases, respectively. AO lines were distributed along the arcuate line. SPO lines were continuations of the AO lines, which were distributed to the posterior column from the greater sciatic notch to the lesser sciatic notch. MPO lines were involved in the QP's central area. A simple fracture was found at the proximal AO and SPO lines in 80% and 86% of all displaced fractures, respectively. AO lines distal to the superior rim of the acetabula were confirmed to be comminuted fractures in 32% of all cases.

CONCLUSIONS

In ABC fractures, there was only one QP fragment in nearly 90% of all cases. The QP fractures were mainly present in the QP's peripheral area. More than 80% of the fracture patterns on the cephalic side of the QP were simple. The reduction and internal fixation of QP fractures in ABC fractures should be in the cephalic region.

The use of suprapectineal plate in acetabular fractures via ilioinguinal approach with Stoppa window

Objective

The aim of the study was to investigate the clinical results of open reduction and internal fixation using a suprapectineal buttress plate for specific acetabular fractures.

Methods

We conducted a retrospective study involving thirty-three patients with specific acetabular fractures in an academic level 2 trauma center. We performed the ilioinguinal approach with Stoppa window for buttress plating of the quadrilateral surface. Clinical examination, radiographs and computed tomography were done using criteria described by Matta. Functional outcome was evaluated by visual analog scale (VAS), WOMAC, Harris Hip score modified, Hip disability and Osteoarthritis Outcome Score (HOOS) and modified Merle d’Aubignè scoring system.

Results

Average follow-up was 40.4 months with a minimum of 24 months. Mean age was 59.09 years. The 82% of patients were treated with a suprapectineal plate using ilioinguinal approach with Stoppa window. The 18% of patients required a Kocher-Langenbeck approach in order to get anatomic reduction of posterior wall or column. The 91% of patients were satisfied of their condition during activity of day living and only a small cohort reported walking aids. The worst clinical results were obtained in patients characterized by highest step displacement. Deep infection of surgical wound was observed in 6% of patients. In 3% of patients, one vascular injury occurred during surgery.

Conclusion

Internal fixation using ilioinguinal approach with Stoppa window and a suprapectineal plate to buttress the quadrilateral plate should be considered a viable treatment of some acetabular fractures. Patients can expect a good functional outcome with a low complication rate.

Biomechanical analysis of fixation methods in acetabular fractures: a systematic review of test setups

Purpose

Optimal anatomical reduction and stable fixation of acetabular fractures are important in avoiding secondary dislocation and osteoarthritis. Biomechanical studies of treatment options of acetabular fractures aim to evaluate the biomechanical properties of different fixation methods. As the setup of the biomechanical test can influence the experimental results, this review aimed to analyze the characteristics, comparability and clinical implications of studies on biomechanical test setups and finite element analyses in the fixation of acetabular fractures.

Methods

A systematic literature research was conducted according to the PRISMA guidelines, using the PubMed/MEDLINE and Web of Science databases. 44 studies conducting biomechanical analyses of fixation of acetabular fractures were identified, which met the predefined inclusion and exclusion criteria and which were published in English between 2000 and April 16, 2021. The studies were analyzed with respect to distinct parameters, including fracture type, material of pelvis model, investigated fixation construct, loading direction, loading protocol, maximum loading force, outcome parameter and measurement method.

Results

In summary, there was no standardized test setup within the studies on fixation constructs for acetabular fractures. It is therefore difficult to compare the studies directly, as they employ a variety of different test parameters. Furthermore, the clinical implications of the biomechanical studies should be scrutinized, since several test parameters were not based on observations of the human physiology.

Conclusion

The limited comparability and restricted clinical implications should be kept in mind when interpreting the results of biomechanical studies and when designing test setups to evaluate fixation methods for acetabular fractures.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00068-022-01936-9.

Biomechanical comparison of acetabular fracture fixation with stand-alone THA or in combination with plating

PURPOSE

A common surgical treatment in anterior column acetabular fractures with preexisting osteoarthritis is THA, which is commonly combined with plate osteosynthesis. Implantation of a solitary revision cup cranially fixed to the os ilium is less common. The purpose of this study was to compare the stabilization of anterior column acetabular fractures fixed with a cranial socket revision cup with flange and iliac peg or with a suprapectineal plate osteosynthesis combined with an additional revision cup.

METHODS

In 20 human hemipelves, an anterior column fracture was stabilized by either a cranial socket revision cup with integrated flange (CF = Cup with Flange) or by a suprapectineal plate combined with a revision cup (CP = Cup and Plate). Each specimen was loaded under a stepwise increasing dynamic load protocol. Initial construct stiffness, interfragmentary movements along the fracture line, as well as femoral head movement in relation to the acetabulum were analyzed.

RESULTS

Both groups showed comparable initial construct stiffness (CP: 3180 ± 1162 N/mm and CF: 3754 ± 668 N/mm; p = 0.158). At an applied load of 1400 N, interfragmentary movements at the acetabular (p = 0.139) and the supraacetabular region (p = 0.051) revealed comparable displacement for both groups and remained below 1 mm. Femoral head movement in relation to the acetabulum also remained below 1 mm for both test groups (p = 0.260).

CONCLUSION

From a biomechanical point of view, both surgical approaches showed comparable fracture reduction in terms of initial construct stiffness and interfragmentary movement. The potential benefit of the less-invasive cranial socket revision cup has to be further investigated in clinical studies.

Finite element analysis of infra-acetabular screw fixation for the treatment of acetabular posterior column fracture

BACKGROUND

Infra-acetabular screws have been described to increase the fixation strength of acetabular fractures with separation of the columns. Previous studies were based on the simulation of the anterior column fractures without modelling the biomechanical effect of the screw in the posterior column fractures. The purpose of this study was to compare the stability of different internal fixation models of posterior column fracture and to provide a theoretical basis for the clinical application of infra-acetabular screws.

METHODS

Five internal fixation models of acetabular posterior column fracture were simulated using five implants, including one reconstruction plate (PCP model), one posterior column screw (PCS model), one infra-acetabular screw (PIS model), one infra-acetabular screw and one reconstruction plate (PIS + PCP model), and one infra-acetabular screw and one posterior column screw (PIS + PCS model). After meshing, material parameter, and boundary condition settings, a vertical downward load of 500 N was applied on the surface of the sacrum. To evaluate the biomechanical properties, the stress distribution and von Mises peak stress were recorded and analyzed, and the displacement distributions of the upper and lower fracture surfaces were compared.

RESULTS

In model PCP, the maximum stress of the plate is 71.952 MPa; in model PCS, the maximum stress of the screw is 52.740 MPa; in model PIS, the maximum stress of the screw is 68.985 MPa; in model PIS + PCP, the maximum stress of the plate is 64.695 MPa and the maximum stress of the screw is 39.679 MPa; and in model PIS + PCS, the maximum stress of the posterior column screw is 48.197 MPa and the maximum stress of the infra-acetabular screw is 65.201 MPa. The maximum stresses of implants are all located on the fracture surfaces. The average displacement differences of the upper and lower fracture surfaces are compared as follows: model PIS + PCS (0.03503 mm) < model PIS + PCP (0.08205 mm) < model PCP (0.10096 mm) < model PCS (0.19007 mm) < model PIS (0.23546 mm).

CONCLUSION

With sufficient biomechanical stability, infra-acetabular screws can be used as a supplementary fixation for the treatment of acetabular posterior column fractures. It is recommended to fix the fracture by the combined application of the infra-acetabular screw and posterior column screw.

Is an Anatomical Suprapectineal Quadrilateral Surface Plate Superior to Previous Fixation Methods for Anterior Column-Posterior Hemitransverse Acetabular Fractures Typical in the Elderly?: A Biomechanical Study

Background

This study aimed to compare the mechanical characteristics of four fixation methods including an anatomical suprapectineal quadrilateral surface (QLS) plate in hemipelvic models of anterior column-posterior hemitransverse acetabular fractures typical in elderly patients.

Methods

In total, 24 composite hemipelvic models were used and allocated to four groups: group 1, pre-contoured anatomical suprapectineal QLS plate; group 2, suprapectineal reconstruction plate with two periarticular long screws; group 3, suprapectineal reconstruction plate with a buttress reconstruction plate; group 4, suprapectineal reconstruction plate with a buttress T-plate. Axial structural stiffness and displacement of each column fragment in four different fixation constructs were compared.

Results

Multiple group comparisons of axial structural stiffness demonstrated significant difference (p = 0.001). Although there was no significant difference between groups 1 and 2 (p = 0.699), group 1 showed greater stiffness than groups 3 and 4 (p = 0.002 and 0.002, respectively). Group 1 showed less displacement in the anterior region of the anterior fragment than group 4 (p = 0.009) and in the posterior region than groups 3 and 4 (p = 0.015 and p = 0.015, respectively). However, group 1 demonstrated greater displacement than group 2 in the posterior region of the posterior fragment (p = 0.004), while showing similar displacement to groups 3 and 4.

Conclusions

The anatomical suprapectineal QLS plate provided the mechanical stability comparable or superior to other existing fixations in osteoporotic models of anterior column-posterior hemitransverse acetabular fractures typical in the elderly. However, additional plate modification would be needed for better stability and outcomes.

The effect of an infra-acetabular screw for anatomically shaped three-dimensional plate or standard plate designs in acetabulum fractures: a biomechanical analysis

Background

Various plate shapes and implant configurations are used for stabilization of acetabulum fractures via anterior approaches. Little is known about the biomechanical stability of a two-dimensionally shaped “conventional” plate (“J-Plate”—JP) in comparison to three-dimensionally shaped plate configurations (3DP). In addition, the augmentary effect of an infra-acetabular lag-screw (IACS) fixation for anterior column and posterior hemi-transverse acetabulum fractures has not been clarified in comparison of JP and 3DP constructs. This study analyzed the difference between the biomechanical stability of JP compared to 3DP and the role of an IACS in a standardized acetabular fracture model in a single-leg stance loading configuration.

Methods

In an artificial bone substitute pelvis model (Synbone^© Malans, Switzerland), a typical and standardized fracture pattern (anterior column and posterior hemi-transverse) was created with osteotomy jigs. After anatomic reduction the stabilization was performed using JP or 3DP. Eight pelvises per group were axially loaded in a single-leg stance model up to 400 N. After the load cycle, an additional infra-acetabular screw was placed and the measurement repeated. Fragment displacement was recorded by an optical tracking system (Optitrack Prime 13®, Corvallis, USA).

Results

In the pure placement, 3DP provided significantly superior stability when compared to JP. Augmentation of JP by IACS increased the stability significantly, up to the level of 3DP alone, whereas augmentation of the 3DP did not result in further increase of overall stability.

Conclusion

The anatomically shaped plate alone provides a superior biomechanical stability in fixation of an anterior column and posterior hemi-transverse fracture model. In a JP fixation the augmentation by IACS provides similar strength as the anatomically shaped 3DP. By use of the anatomically shaped 3DP the need of a clinically risky application of IACS might be avoidable.

Level of evidence

IV, Experimental study.

Finite Element Analysis of a Novel Anatomical Locking Guide Plate for Anterior Column and Posterior Hemi-Transverse Acetabular Fractures

Purpose

The increasing worldwide prevalence of anterior column-posterior hemi-transverse fracture (ACPHTF) brings formidable challenges to orthopaedic surgeons. Our newly-designed locking plate had previously demonstrated promising effects in ACPHTF, but evidence of their direct comparison with conventional internal fixations remains lacking. In this study, we aimed to compare our novel plate with the traditional devices via finite element analysis.

Methods

The ACPHTF model was created based on a 48-year-old volunteer’s CT data, and then fixed in three different internal fixations: an anterior column locking plate with posterior column screws, double column locking plates, and our novel anatomical locking plate. These models were next loaded with a downward vertical force of 200 N, 400 N and 600 N, and the stress peaks and displacements of three different sites were recorded and analyzed.

Results

We first tested the rigidity and found that our newly-designed locking plate as well as its matched screws had a greater stiffness especially when they were under a higher loading force of 600 N. Then we evaluated the displacements of fracture ends after applying these fixations. Both our novel plate and DLP showed significantly smaller displacement than LPPCS at the anterior column fracture line and the pubic branch fracture line, while our novel plate was not obviously inferior to DLP in terms of the displacement.

Conclusion

This novel plate demonstrates a distinct superiority in the stiffness over LPPCS and DLP and comparable displacements to DLP in ACPHTF, which suggests this novel anatomical locking guide plate should be taken into consideration in ACPHTF.

Usefulness of the obturator hook technique for guiding the initial trajectory control in infra-acetabular screw placement

PURPOSE

Proper placement of infra-acetabular screws is technically demanding; there is a limited safe zone for screw fixation because of the complexity of the bone anatomy around the hip joint and the vulnerability of the major neurovascular bundles in the pelvic cavity. We aimed to present the obturator hook technique as a surgical technique for infra-acetabular screw placement in acetabular and pelvic fractures and report its radiological outcomes.

METHODS

Patients treated with infra-acetabular screw placement using the obturator hook technique between January 2015 and August 2020 were enrolled in this study. We collected data on demographics, surgical approach, reduction status, complications, and outcomes. The radiological outcomes of infra-acetabular screw placement based on computed tomography findings were evaluated as follows: success, articular penetration, or out of the bone.

RESULTS

Thirty-five patients underwent infra-acetabular screw placement (26 men, 9 women; mean age, 55 years; range, 27-90 years). One patient underwent bilateral infra-acetabular screw placement; therefore, 36 infra-acetabular screws were inserted in all patients. An ideal placement was achieved with 27 infra-acetabular screws (27/36, 75%). Seven infra-acetabular screws (7/36, 19%) showed articular penetration, and two infra-acetabular screws (2/36, 6%) were placed outside the bone. One patient with articular penetration and mechanical symptoms of the hip joint required screw replacement. No other complications, including obturator nerve and vascular injuries, were observed.

CONCLUSION

The obturator hook technique could be a favorable and individualized method for infra-acetabular screw placement in patients with acetabular and pelvic fractures.

LEVEL OF EVIDENCE

IV, retrospective descriptive study.

Which radiograph is most accurate for assessing hip joint penetration in infra-acetabular screw placement?

Although infra-acetabular screws have been used for anterior and posterior column transfixation, a screw penetrating the hip joint can result in harmful complications. However, the most accurate intraoperative radiologic imaging tool for identifying articular penetration has not been established. The purpose of the present study was, therefore, to evaluate the consistency with which standard pelvic radiographs compared with computed tomography (CT) can be used for demonstrating articular penetration.This retrospective review was performed between January 2015 and December 2020. We evaluated the records of patients with acetabular or pelvic fractures who underwent open reduction and internal fixation with infra-acetabular screw placement. We collected demographic data and described infra-acetabular screw placement as follows: ideal placement, articular penetration, and out of the bone. Articular penetration was assessed independently on each pelvic radiograph and compared statistically with the CT scans. Sensitivity, specificity, correct interpretation rate, and prevalence-adjusted bias-adjusted kappa (PABAK) were calculated for each radiograph.Thirty-nine patients underwent infra-acetabular screw placement. The mean age of patients was 55 years (range, 27-90 years); there were 29 men and 10 women. One patient underwent bilateral infra-acetabular screw placement; therefore, 40 infra-acetabular screws were included in total. Six (6/40, 15%) infra-acetabular screws showed articular penetration on CT and two (2/40, 5%) showed infra-acetabular screws extending out of the bone. Hip joint penetration was correctly identified at a rate of 92.5% (95% confidence interval [CI], 79.6-98.4%) on the outlet view and 87.5% (95% CI, 73.2-95.8%) on the anteroposterior (AP) view. The PABAK for the agreement between pelvic radiographs and CT scans was 0.85 in the outlet view and 0.75 in the AP view.The outlet view is an accurate method for detecting articular penetration of infra-acetabular screws. We recommend the insertion of an infra-acetabular screw under fluoroscopic outlet view to avoid articular penetration intraoperatively.

Quadrilateral Surface Restoration by Medial Buttressing Before Revision in Periprosthetic Acetabular Fracture: A Case Report

CASE

We report a case of periprosthetic acetabular fracture with pelvic discontinuity (PAFPD) classified Paprosky IIIb around an infected hip resurfacing prosthesis. A 3-stage revision was performed with (1) implants removal and surgical debridement to treat the infection; (2) open reduction and internal fixation using a medial buttress plate to treat pelvic discontinuity; and (3) custom-made total hip replacement with acetabular-ring reinforcement. The patient recovered with excellent clinical and radiographic results at 4-year follow-up.

CONCLUSIONS

In complex cases of PAFPD, a collaboration between pelvic trauma surgeons and orthopaedic hip surgeons allows to provide stability for revision surgeries with good 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.

Double column acetabular fractures fixation using a novel dynamic anterior plate-screw system: A biomechanical analysis

BACKGROUND

According to the classification of Judet and Letournel, all double column acetabular fractures will certainly involve the disruption of the quadrilateral plate (QLP). Accurate reduction and reliable fixation of QLP is the key to obtain a normal congruent hip joint and avoid postoperative arthritis. The aims of this study were to assess the biomechanical properties of a novel dynamic anterior plate-screw system (named DAPSQ) and to compare its biomechanical stability with buttress-plate construct.

METHODS

Double column acetabular fractures involving the QLP were created on cadaveric pelvic specimens and subsequently stabilized with (1) a pre-contoured side-specific DAPSQ titanium plate and 4 quadrilateral screws (Group A) or a 12-hole suprapectineal pelvic reconstruction plate combined with a 9-hole 1/3 tube buttress plate (Group B). These constructs were mechanically loaded on ZwickZ 100 testing machine. Construct stiffness and displacement amounts of the two fixation methods in the condition of dynamic axial loading conditions were measured.

RESULTS

As the axial loading force increased from 200 N to 800 N, the longitudinal displacement of each pelvic specimen increased linearly and Group B was found to have significantly higher displacement than Group A (p<0.05). In the 600 N physiological loading, the construct stiffness values of Groups A and B were 139.4 ± 37.4 N/mm and 101±18.3 N/mm, respectively. Group A is 27% stiffer than Group B(p<0.05).

CONCLUSIONS

In this in vitro biomechanical study, DAPSQ plate and quadrilateral screws fixation of a double column acetabular fracture involving the QLP resulted in a better fixation construct than the traditional suprapectineal pelvic reconstruction plate and 1/3 tube buttress plate fixation.

Biomechanical analysis of fixation methods for acetabular fractures: A review

Acetabular fractures are known as one of the most frequent types of pelvic fractures with growing frequency among elderly people. Because of this, it is important to establish the methods of repair that will produce optimal outcomes for fracture healing and joint remobilization. Open reduction and internal fixation are considered as the "gold standard" of acetabular fracture repair; however, to the best of authors' knowledge, there is no systematic review comparing different repair methods from biomechanical point of view. As such, in this review paper, we summarize the results of English language literature biomechanically focused on acetabular fracture fixation methods in the last thirty years with the aim to create a reference for clinical decision making. The selected literature within the review is broken down into categories based on type of fracture, i.e., simple or complex, and then further grouped based on fracture line orientation. Clinical recommendations and future research possibilities are also provided.

Medial buttressing of the quadrilateral surface in acetabular and periprosthetic acetabular fractures

Background

In geriatric acetabular fractures, the quadrilateral plate is often involved in the fracture pattern and medially displaced. Open reduction and internal fixation (ORIF) includes reduction of the quadrilateral plate and securing its position. In this study, the concept of medial buttressing in acute and periprosthetic acetabular fractures is evaluated.

Materials and methods

Patients, who sustained an acetabular fracture between 2012 and 2018, in whom ORIF with a specific implant for medial buttressing was performed, were included in the study. Patients were divided in two groups; acute acetabular fractures (group 1) and periprosthetic acetabular fractures (group 2). Demographics, type of fracture, surgical approach, type of implant for medial buttressing, comorbidities, general and surgical in-hospital complications and length of hospital stay were recorded retrospectively. The following data were collected from the surviving patients by telephone interview: EQ-5D-5L, SF-8 physical and SF-8 mental before trauma and at follow-up, UCLA activity scale, Parker Mobility Score and Numeric Rating Scale.

Results

Forty-six patients were included in this study, 30 males (65.2%) and 16 females (34.8%). Forty patients were included group 1 and six patients in group 2. The median age of patients of group 1 was 78 years. Among them, 82.5% presented with comorbidities. Their median length of in-hospital stay was 20.5 days. 57.5% of patients suffered from in-hospital complications. The concept of medial buttressing was successful in all but one patient. ORIF together with primary total hip arthroplasty (THA) was carried out as a single stage procedure in 3 patients. Secondary THA was performed in 5 additional patients (5/37 = 13.5%) within the observation period. Among surviving patients, 79.2% were evaluated after 3 years of follow-up. Quality of life, activity level and mobility dropped importantly and were lower than the values of a German reference population. SF-8 mental did not change. The median age of patients of group 2 was 79.5 years, all of them presented with one or several comorbidities. The median length of in-hospital stay was 18.5 days. 50% of patients suffered from in-hospital complications. The concept of medial buttressing was successful in all patients. 5 of 6 patients (83.3%) could be evaluated after a median of 136 weeks. In none of these patients, secondary surgery was necessary. Quality of life, activity level and mobility importantly dropped as well in this group. SF-8 mental remained unchanged.

Conclusion

In geriatric acetabular fractures with involvement and medial displacement of the quadrilateral plate, medial buttressing as part of ORIF proved to be reliable. Only 13.5% of patients of group 1 needed a secondary THA within 3 years of follow-up, which is lower than in comparable studies. Despite successful surgery, quality of life, activity level and mobility dropped importantly in all patients. The loss of independence did however not influence SF-8 mental values.

A new internal fixation technique for acetabular fractures involving the quadrilateral plate

BACKGROUND

The treatment of acetabular fracture involving the quadrilateral plate is a technical challenge, and the optimal management of the fracture remains controversial. We have designed a new implant (named acetabular fracture reduction internal fixator, AFRIF) for acetabular fractures involving the quadrilateral plate. This use of this new device was not investigated therefore we conducted a retrospective study aiming to determine whether the AFRIF can achieve satisfactory clinical and radiological outcomes for quadrilateral plate fracture.

HYPOTHESIS

The AFRIF for quadrilateral plate fracture is an acceptable option to treat acetabular fracture involving the quadrilateral plate.

MATERIALS AND METHODS

We performed a retrospective analysis of prospectively collected data on 24 patients (15 males and 9 females) with acute displaced quadrilateral plate fractures of the acetabulum who were treated by the AFRIF between August 2011 and May 2015. The mean age of the patients was 61.5±9.2 years (range, 31-82 years). All hips had protrusion of the femoral head, of these 5 hips with associated articular impaction of the medial roof. The type of fractures included anterior column in 4, anterior column+posterior hemitransverse in 3, associated both column in 11, T-shaped in 6 patients. The approaches included Limited Ilioinguinal (5 patients) and Limited Standard-Ilioinguinal combined with Kocher-Langenbeck (19 patients). Quality of reduction was evaluated and graded as anatomical (0mm to 1mm of displacement), imperfect (2mm to 3mm displacement) or poor (more than 3mm displacement) according to the residual displacement as defined by Matta. The final follow-up clinical outcome was classified as excellent (18 points), good (15-17 points), fair (13-14 points) or poor (<13 points) in terms to the modified Merle d'Aubigné-Postel score, and radiological outcomes evaluation were as excellent, good, fair, or poor based on Matta score.

RESULTS

The mean duration of follow-up was 45.7±13.0 months (range, 24-60 months). Average operative time and bleeding amount was 110.3±30.8min (range, 105-210min) and 950.6±348.6ml (range, 300-1500ml), respectively. There was anatomical reduction in 17 patients (17/24, 70.8%), imperfect in 5 patients (5/24, 20.8%), and poor in 2 patients (2/24, 8.3%). All of the quadrilateral plate fractures achieved anatomical except one imperfect reduction. No re-protrusion of the femoral head was observed at the final follow-up. The mean modified Merle d'Aubigné-Postel score was 16.9±2.0 points (range, 10-18 points), and 83.3% (20 of 24) have good or excellent radiological outcomes.

DISCUSSION

The findings suggest that the AFRIF for quadrilateral plate fractures may prevent protrusion of the femoral head and achieve good to excellent clinical and radiological outcomes.

LEVEL OF EVIDENCE

IV, retrospective study.

Biomechanical Comparison of Different Fixation Techniques for Typical Acetabular Fractures in the Elderly: The Role of Special Quadrilateral Surface Buttress Plates

BACKGROUND

Anterior column-posterior hemitransverse fractures are prevalent in the elderly and are often associated with quadrilateral surface (QLS) comminution. Several special QLS buttress plates have been introduced, but evidence of their comparability with traditional fixation devices is lacking. This biomechanical study aimed to compare special QLS buttress plates with traditional fixation devices.

METHODS

Anterior column-posterior hemitransverse fractures with an isolated QLS fragment were created on 24 composite hemipelves and were allocated to 4 fixation groups: (1) infrapectineal QLS buttress plate, (2) suprapectineal QLS buttress plate, (3) suprapectineal reconstruction plate with 3 periarticular long screws, and (4) infrapectineal reconstruction plate with 3 periarticular long screws. Specimens were loaded to simulate partial weight-bearing (35 to 350 N) or full weight-bearing (75 to 750 N). A testing machine was synchronized with a 3-dimensional video tracking system to optically track displacement at the points of interest and to calculate construct stiffness. The fixation systems were compared using the Kruskal-Wallis and Mann-Whitney U tests.

RESULTS

The experimental results of the partial and full weight-bearing simulations were surprisingly similar. During 40 loading cycles, the maximum displacement on the 6 predetermined points did not exceed 1.1 mm. Multiple-group comparisons of relative displacements of each predetermined measurement point did not differ significantly (p > 0.05). The suprapectineal reconstruction plate with 3 periarticular long screws demonstrated the greatest construct stiffness and significantly greater stiffness than the infrapectineal plate with long screws (p < 0.017). However, no significant difference (p > 0.017) in stiffness was identified between the infrapectineal QLS buttress plate and the suprapectineal reconstruction plate with long screws.

CONCLUSIONS

The suprapectineal pelvic brim plate with 3 periarticular long screws remains the gold standard to treat anterior column-posterior hemitransverse fractures. The special infrapectineal QLS buttress plate provides stiffness and stability comparable with those of standard fixation. However, moving the pelvic brim plate from the suprapectineal border to the infrapectineal border is not recommended for anterior column-posterior hemitransverse fractures because it significantly decreases fixation stiffness.

CLINICAL RELEVANCE

Special QLS buttress plates may be an alternative fixation method for anterior column-posterior hemitransverse acetabular fractures in the elderly, especially when a less invasive anterior intrapelvic approach is selected.

Three-dimensional printing of patient-specific plates for the treatment of acetabular fractures involving quadrilateral plate disruption

Background

Complicated acetabular fractures comprise the most challenging field for orthopedists. The purpose of this study was to develop three-dimensional printed patient-specific (3DPPS) Ti-6Al-4 V plates to treat complicated acetabular fractures involving quadrilateral plate (QLP) disruption and to evaluate their efficacy.

Methods

Fifty patients with acetabular fractures involving QLP disruption were selected between January 2016 and June 2017. Patients were divided into a control group (Group A, 35 patients) and an experimental group (Group B, 15 patients), and were treated by the conventional method of shaping reconstruction plates or with 3DPPS Ti-6AL-4 V plates, respectively. The efficacy of Ti-6AL-4 V plates was evaluated by blood loss, operative time, reduction quality, postoperative residual displacement, and complications.

Results

The operative time and blood loss in Group B were reduced compared to Group A, and the difference was statistically significant (P < 0.05). There was no significant difference in reduction quality between the two groups (P > 0.05). Reduction quality in Group B was anatomic in 10 (66.7%), satisfactory in four (26.7%), and poor in one (6.7%). In Group A, they were anatomic in 18 (51.4%), satisfactory in 13 (37.1%), and poor in four (11.4%). Residual displacement in Group B was less than that in Group A, and the difference was statistically significant (P < 0.05). In Group B, one case exhibited loosening of the pubic screw postoperatively. In Group A, there was one case of wound infection, one of deep vein thrombosis (DVT) in the ipsilateral lower limb, one case of traumatic arthritis and two obturator nerve injuries.

Conclusions

The 3DPPS Ti-6AL-4 V plate is a feasible, accurate and effective implant for acetabular fracture treatment.

Comparison of two reinforcement rings for primary total hip arthroplasty addressing displaced acetabular fractures: a biomechanical analysis

INTRODUCTION

Aim of this study was to biomechanically compare two different acetabular cup fixation constructs in terms of fracture fixation for displaced acetabular fractures involving the anterior column with hemitransverse fracture under partial and full weight-bearing conditions.

METHODS

Two different reinforcement rings designed as cages for primary THA were biomechanically tested in terms of managing a complex acetabular fracture. Single-leg stance cyclic loading was performed to assess fracture gap movement and fragment rotation. Twelve hemi pelvis Sawbones were divided into two groups: primary THA with acetabulum roof reinforcement plate (ARRP) (n = 6) and primary THA with Burch-Schneider reinforcement cage (BSRC) (n = 6).

RESULTS

During loading under partial weight-bearing (250 N) fracture gap movement tended to be larger in the BSRC group as compared to the ARRP group. Under full weight-bearing conditions, the ARRP showed 60% significantly less motion (p = 0.035) of the os ilium to os ischii gap compared to BSRC. Fracture gap movements between the os ilium and spina iliaca fragments were significantly reduced by 76% (p = 0.048) for ARRP in contrast to BSRC. The ARRP group also demonstrated significantly less movement in the fracture gaps os ischii to quadrilateral plate (62% reduction, p = 0.009) and quadrilateral plate to spina iliaca (87% reduction, p < 0.001). Significantly less rotational movement of the quadrilateral plate to the os ilium was exhibited by the ARRP group (p = 0.015).

CONCLUSIONS

The presented acetabulum roof-reinforcement plate (ARRP) provides stable conditions at the acetabular component with adequate stabilization of a displaced acetabular fracture.

Use of a stainless steel locking calcaneal plate for quadrilateral plate buttress in the treatment of acetabular fractures

Operative fixation of acetabular fractures involving the quadrilateral surface presents a challenging clinical scenario. Classically, quadrilateral plate buttress was achieved via the use of a "seven" plate. More recently, the use of an anatomic, pre-contoured design has been gaining popularity due to its pre-contoured shape and larger footprint, allowing for a wider quadrilateral plate buttress. The current study presents using a stainless steel locking calcaneal plate to obtain similar surface area coverage as the modern pre-contoured quadrilateral plate, but at a lower cost.Level of evidence IV.

Treatment results for acetabulum fractures using the modified Stoppa approach

Objectives

The aim of this study was to evaluate the clinical and radiological results of the surgical treatment of acetabular fractures using modified Stoppa approach.

Methods

A total of 57 patients (mean age 37.8 years; range 15–84) who underwent surgical treatment for acetabular fracture with modified Stoppa approach from February 2013 to June 2016 were included into the study. The mean follow-up time was 28.1 months (range 24–35). The records were reviewed for fracture patterns, time to surgery, operative time, blood loss, reduction quality, and perioperative complications. Reduction quality was graded as anatomic, imperfect, or poor. The Harris Hip Score (HHS) and Merle d'Aubigné score were used for functional evaluation.

Results

Among the 63 acetabulum fractures of the 57 patients, 27 were associated with both columns, 12 were T-type fractures, 10 were transverse, 7 were anterior column/posterior hemitransverse, 5 were anterior column, and 2 were anterior wall fracture. A single surgeon performed all operations. Pfannenstiel incision was used in the first 19 cases while vertical midline incision in the remaining 38 cases. Average time to operation was 5.5 days, and supplemental lateral windows were used in 17 (29.8%) patients. Average blood loss and operation times were 660 mL and 152 min, respectively. Radiological outcomes were anatomic, imperfect, and poor in 52 (82.5%), 9 (14.2%), and 2 (3.2%) of the acetabulum fractures, respectively. Clinical outcomes at 2 years with HHS and Merle d’Aubigné scores were mean 86.6 (range 66–96) (Excellent in 27, good in 23, fair in 4, poor in 3 patient) and 16.7 (range 10–18) (Excellent in 25, very good in 18, good in 6, fair in 5, poor in 3 patient), respectively. There was a significant relation between the reduction quality and clinical outcome (p < 0.001), while there was no significant relation between the clinical outcome and the fracture type (p > 0.05). Iatrogenic external iliac vein damage was noted in 2 patients. Obturator nerve palsy was noted in 3 patients, who recovered spontaneously at mean time of 3.7 months (range 3–5). Rectus abdominus paralysis was noted in 2 of the 19 (10.5%) Pfannenstiel-incision patients but not in the vertical-incision patients.

Conclusion

Our experience in 57 patients shows that satisfactory results can be obtained, even in bilateral fractures with vertical midline incision.

Level of evidence

Level IV Therapeutic Study