Fluoroscopically guided acetabular posterior column screw fixation via an anterior approach

Acetabular fractures in geriatric patients: epidemiology, pathomechanism, classification and treatment options

The incidence of geriatric acetabular fractures has shown a sharp increase in the last decades. The majority of patients are male, which is different to other osteoporotic fractures. The typical pathomechanism generally differs from acetabular fractures in young patients regarding both the direction and the amount of force transmission to the acetabulum via the femoral head. Geriatric fractures very frequently involve anterior structures of the acetabulum, while the posterior wall is less frequently involved. The anterior column and posterior hemitransverse (ACPHT) fracture is the most common fracture type. Superomedial dome impactions (gull sign) are a frequent feature in geriatric acetabular fractures as well. Treatment options include nonoperative treatment, internal fixation and arthoplasty. Nonoperative treatment includes rapid mobilisation and full weighbearing under analgesia and is advisable in non- or minimally displaced fractures without subluxation of the hip joint and without positive gull sign. Open reduction and internal fixation of geriatric acetabular fractures leads to good or excellent results, if anatomic reduction is achieved intraoperatively and loss of reduction does not occur postoperatively. Primary arthroplasty of geriatric acetabular fractures is a treatment option, which does not require anatomic reduction, allows for immediate postoperative full weightbearing and obviates several complications, which are associated with internal fixation. The major issue is the fixation of the acetabular cup in the fractured bone. Primary cups, reinforcement rings or a combination of arthroplasty and internal fixation may be applied depending on the acetabular fracture type.

Acetabular posterior column screws via an anterior approach

Screw fixation of acetabular column fractures is a well-established alternative option to plate fixation providing comparable biomechanical strength and requiring less surgical exposure. For displaced acetabular fractures involving both columns open reduction and plate fixation of one column in combination with a column-crossing screw fixation of the opposite column via a single approach is a viable treatment option. Preoperative planning of posterior column screws (PCS) via an anterior approach is mandatory to assess the eligibility of the fracture for this technique and to plan the entry point and the screw trajectory. The intraoperative application requires fluoroscopic guidance using several views. A single view showing an extraarticular screw position is adequate to rule out hip joint penetration. The fluoroscopic assessment of cortical perforation of the posterior column requires several oblique views such as lateral oblique views, obturator oblique views and axial views of the posterior column or alternatively intraoperative CT scans. The application of PCS via an anterior approach is a technically demanding procedure, that allows for a relevant reduction of approach-related morbidity, surgical time and blood loss by using a single approach.

Fluroscopy-assisted transiliac antegrade lag screw placement technique in both columns of acetabulum: A novel procedure

The use of pelvic osseous fixation corridors and lag screw fixation in acetabular and pelvic surgery has gained popularity, especially with the recent development of intraoperative imaging and navigation techniques. However, advanced intraoperative imaging and navigation techniques require technical equipment and are costly. Therefore, traditional fluoroscopic techniques still maintain their importance. In this article, we describe a novel pelvic osseous fixation corridor that traverses both columns of the acetabulum, along with the detailed methodology of its fluoroscopic imaging and the techniques for fluoroscopy-assisted screw placement. The technique of placing screws in this current fixation corridor is only under fluoroscopy assistance, without using any specially produced guide or navigation device. LEVEL OF PROOF: IV.

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.

Comparison between Novel Anatomical Locking Guide Plate and Conventional Locking Plate for Acetabular Fractures: A Finite Element Analysis

The treatment of complex acetabular fractures remains a complicated clinical challenge. Our self-designed novel anatomical locking guide plate (NALGP) has previously shown promising potential in T-shaped acetabular fractures (TAF), but a direct comparison with conventional fixations is yet to be made. The TAF model was established based on a volunteer's computer tomography data and then fixed with double column locking plates (DLP), a posterior column locking plate with anterior column screws (LPACS), and our NALGP. Forces of 200 N, 400 N, and 600 N were then loaded on the model vertically downward, respectively. The stress distribution and peaks and maximum displacements at three sites were assessed. We found that the stress area of all three plates was mainly concentrated around the fracture line, while only the matching screws of the NALGP showed no obvious stress concentration points. In addition, the NALGP and DLP showed significantly less fracture fragment displacement than the LPACS at the three main fracture sites. The NALGP was found to have less displacement than DLP at the posterior column and ischiopubic branch sites, especially under the higher loading forces of 400 N and 600 N. The fixation stability of the NALGP for TAF was similar to that of DLP but better than that of LPACS. Moreover, the NALGP and its matching screws have a more reasonable stress distribution under different loads of force and the same strength as the LPACS.

Use of the iliac-outlet and iliac-inlet combined views in percutaneous posterior column retrograde screw fixation

Posterior column fractures are common acetabular injuries. Although displaced fractures require open reduction and fixation, undisplaced patterns may benefit from percutaneous screw fixation. The combination of iliac oblique with inlet and outlet views offers an intuitive and panoramic rendering of the bony corridor into the posterior column; lateral cross table view completes the sequence of fluoroscopic projections. Herein we describe the use of outlet/inlet iliac views and a detailed procedure for percutaneous retrograde posterior column screw fixation.

The difference in the corridor of the antegrade posterior column screw according to the presence of pelvic dysmorphism

INTRODUCTION

Antegrade posterior column screw (aPCS) fixation via the anterior approach has been widely used for separated the posterior columns in acetabular fracture treatment. Although the relationship between pelvic dysmorphism and sacroiliac screws has been widely studied, no studies have reported on the clinical impact of pelvic dysmorphism on acetabular fractures. This study aimed to reveal the difference in the insertion angle and entry point of aPCS between the dysmorphic and normal pelvises.

METHODS

Patients diagnosed with unilateral acetabular fractures and who underwent pelvic computed tomography scans between 2013 and 2019 in two institutes were enrolled in this study. Patients were divided into the dysmorphic and control groups according to the sacral dysmorphic score, which predicts the presence of pelvic dysmorphism, and each group enrolled 130 patients. The semitransparent 3D hemipelvis model was reconstructed using a 3D reconstruction program. The sagittal and coronal angles of a virtual cylinder that fill the safe corridor of the column screw the most were measured. The surface area of the safe corridor and distance of the optimal entry point from the anterior border of the sacroiliac joint were analyzed. The measurements were compared between the dysmorphic and control groups.

RESULTS

The average sacral dysmorphic score in the normal and dysmorphic pelvis groups was 56.1 and 81.0, respectively. There were no significant differences in demographic data, including age, sex, height, weight, and body mass index, between the dysmorphic and control groups. There was a significant difference in the average sagittal insertion angle of PCs, which was 38.3° in the control group and 27.2° in the dysmorphic group (P < 0.001). The coronal insertion angles were not significantly different. The dysmorphic group presented longer straight distances (25.9 vs 24.8 mm, P = 0.026) and had a smaller aPCS surface area (685 vs 757 mm², P < 0.001) than the control group.

CONCLUSION

The present study describes a difference in the corridor of aPCS between the dysmorphic and normal pelvis. Insertion of aPCS in the dysmorphic pelvis requires a more acute angular trajectory in the sagittal plane than that in the normal pelvis.

Acetabular defect management and revision arthroplasty via the direct anterior approach

OBJECTIVE

Acetabular revision arthroplasty and osseous defect management through the direct anterior approach (DAA) with or without proximal extension.

INDICATIONS

Aseptic or septic component loosening, periacetabular osseous defects, pelvic discontinuity, intrapelvic cup protrusion, anterior pseudotumors, iliopsoas tendonitis, polyethylene wear or iliopsoas abscess.

CONTRAINDICATIONS

Clinically relevant gluteal tendon lesions, active infection, morbid obesity, large abdominal pannus, ASA (American Society of Anesthesiologists) score > III, inguinal skin infection.

SURGICAL TECHNIQUE

Electrocautery dissection is recommended to dissect the Hueter interval and to debulk pericapsular scar tissue. At all times during capsular debulking, it should be made sure not to damage the iliopsoas tendon or the neurovascular bundle. A stepwise releasing sequence can facilitate dislocation of the prosthesis. Most cases can be revised via the standard DAA but certain circumstances require an intra- or extrapelvic extension. Access to the anterior gluteal surface of the ilium can be provided using a "tensor snip". More posterior access is provided by the extensile extrapelvic approach described by Smith-Petersen. The intrapelvic Levine extension offers access to the entire visceral surface of the ilium and large parts of the anterior column.

POSTOPERATIVE MANAGEMENT

Patient revised via the intra- or extrapelvic extension and patients suffering from extensive soft tissue or osseous defects should undergo postoperative weight-bearing restrictions with 20 kg for 6 weeks.

RESULTS

Based on our studies, there is no limitation on the type of acetabular implant that can be used in DAA revision arthroplasty. Moreover, virtually all types of periacetabular osseous defects can be managed through the approach and its extensions. Acetabular revision arthroplasty via the DAA and its extensions is safe and can result in good midterm results.

Three-dimensional mapping study of pure transverse acetabular fractures

BACKGROUND

To describe and analyze the morphological characteristics, location and frequency of pure transverse acetabular fracture lines through fracture mapping and quantitative measurements.

METHODS

Transverse fractures were retrospectively reviewed and analyzed. All computed tomography (CT) data were used for reconstruction and manual reduction. The reductive fracture fragments were graphically overlaid onto a three-dimensional (3D) right hemipelvis template. Then, the fracture lines were accurately depicted onto the surface of the 3D template. The fracture lines were overlapped onto the model to create the 3D fracture map and heatmap. All cases were subdivided into infratectal (62-B1.1), juxtatectal (62-B1.2), and transtectal (62-B1.3) types based on the AO Foundation/Orthopedic Trauma Association (AO/OTA) classification. Some anatomic parameters of the transverse fractures were also analyzed in these 3 groups.

RESULTS

Our study included forty-nine transverse fractures from 32 male and 17 female patients (mean age, 42 years; range 21-74 years) and included 19 type 62-B1.1, 17 type 62-B1.2, and 13 type 62-B1.3 fractures. The average anterior rim fracture angle was 70.0° (± 11.6°), and the posterior rim fracture angle was 92.4° (± 28.5°). The anterior rim fracture angles in 40 cases (40/49, 81.6%) fell within a wide range between 63° and 80°. On the heatmap, the hot zones were located on the highest position of the cotyloid fossa and the narrowed region, and the cold zone was on the inferior third of the articular surface. For type 62-B1.3 fractures, the hot zone was located on the posterior of the acetabular dome. There were no significant differences in anterior rim fracture angle and anterior height among the three patterns (P = 0.071, P = 0.072). Post hoc tests of the posterior rim fracture angle and the posterior height revealed significant differences among fracture subtypes (P < 0.01). The posterior intra-articular fracture line was significantly longer than the anterior intra-articular fracture line in type 62-B1.1 and type 62-B1.2 fractures (P < 0.01).

CONCLUSION

The fracture lines of transverse fractures through the anterior rim were concentrated on the narrowed zone, and the posterior fracture lines were diffusely distributed. The intra-articular fracture line distribution was focused on the superior and middle thirds of the joint surface. The recurrent fracture lines involving the weight-bearing dome mainly converged on the posterior region of the roof.

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.

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.

Biomechanical comparison of fixation techniques for transverse acetabular fractures - Single-leg stance vs. sit-to-stand loading

OBJECTIVES

To biomechanically compare five different fixation techniques for transverse acetabular fractures using both the single-leg stance (SLS) and the sit-to-stand (STS) loading protocols and to directly compare fracture gap motion (FGM) and relative interfragmentary rotation (RIFR).

METHODS

Transtectal transverse acetabular fractures were created on fourth-generation composite hemipelves in a reproducible manner. Five different fixation techniques were biomechanically assessed using both an SLS and STS loading protocol: anterior plate (AP) only, posterior plate (PP) only, anterior plate plus posterior column screw (AP+PCS), posterior plate plus anterior column screw (PP+ACS) and anterior plus posterior plate (AP+PP). After preconditioning, the specimens were loaded from 50 to 750 N with a ramp of 100 N/s. FGM and RIFR under loads of 750 N were measured using an optical 3D measurement system.

RESULTS

In the three groups of fixation techniques addressing both columns, STS loading resulted in higher mean FGM and in RIFR than SLS loading. No construct failure was observed. In the single plate groups (AP only and PP only), STS loading resulted in failure of all specimens before reaching loads of 750 N, while no failure occurred after SLS loading. No significant differences in FGM and RIFR were found between the double plate (AP+PP) and the single plate plus column screw (AP+PCS and PP+ACS) techniques.

CONCLUSION

SLS loading appeared to overestimate the strength of acetabular fracture fixation constructs and STS loading may be more appropriate to provide clinically relevant biomechanical data. Internal fixation of a single column might not provide adequate stability for transverse fractures, while strength of single plate plus column screw fixation and double plate fixation was comparable.