Screw fixation of ACPHT acetabular fractures offers sufficient biomechanical stability when compared to standard buttress plate fixation

Medial surface plating of posterior column through the anterior intrapelvic approach in acetabulum fractures with involvement of both columns

Aims

Posterior column plating through the single anterior approach reduces the morbidity in acetabular fractures that require stabilization of both the columns. The aim of this study is to assess the effectiveness of posterior column plating through the anterior intrapelvic approach (AIP) in the management of acetabular fractures.

Methods

We retrospectively reviewed the data from R G Kar Medical College, Kolkata, India, from June 2018 to April 2023. Overall, there were 34 acetabulum fractures involving both columns managed by medial buttress plating of posterior column. The posterior column of the acetabular fracture was fixed through the AIP approach with buttress plate on medial surface of posterior column. Mean follow-up was 25 months (13 to 58). Accuracy of reduction and effectiveness of this technique were measured by assessing the Merle d'Aubigné score and Matta's radiological grading at one year and at latest follow-up.

Results

Immediate postoperative radiological Matta's reduction accuracy showed anatomical reduction (0 to 1 mm) in 23 cases (67.6%), satisfactory (2 to 3 mm) in nine (26.4%), and unsatisfactory (> 3 mm) in two (6%). Merle d'Aubigné score at the end of one year was calculated to be excellent in 18 cases (52.9%), good in 11 (32.3%), fair in three (8.8%), and poor in two (5.9%). Matta's radiological grading at the end of one year was calculated to be excellent in 16 cases (47%), good in nine (26.4%), six in fair (17.6%), and three in poor (8.8%). Merle d'Aubigné score at latest follow-up deteriorated by one point in some cases, but the grading remained the same; Matta's radiological grading at latest follow-up also remained unchanged.

Conclusion

Stabilization of posterior column through AIP by medial surface plate along the sciatic notch gives good stability to posterior column, and at the same time can avoid morbidity of the additional lateral window.

Advances in fixation strength of reorienting rectangular triple pelvic innominate osteotomies - A biomechanical investigation of two screw fixation techniques

BACKGROUND

Reorientating pelvic osteotomies are performed to prevent femoral-acetabular impingement or degenerative arthritis. A Toennis-Kalchschmidt triple pelvis innominate osteotomy is used in symptomatic patients. This study aimed to investigate the biomechanical behaviour of two different acetabular screw configurations for triple pelvis innominate osteotomy osteosynthesis.

METHODS

Two screw-orientation techniques in rectangular os ilium osteotomy were compared by osteotomising 12 artificial hemipelvises with triple pelvis innominate osteotomy protocol (fragment reorientation: 10.5° inclination and 10.0° anteversion) and randomising them in 2 groups (n = 6) for implantation with three 4.5 mm screws. Bidirectional group had a bidirectional screw orientation and Monoaxial group had a monoaxial direction of all three screws through iliac crest. All specimens were tested under progressively increasing cyclic loading until failure. Group-wise comparisons of acetabular cup medialisation, anteversion and inclination were evaluated via motion tracking at cycles 250, 500, 750, 1000, 1250, 1500, 1750, 2000, 2250, and 2500. Failure was defined as reaching 5° inclination or 5° anteversion.

FINDINGS

Acetabular cup medialisation (p ≤ 0.026), anteversion (p ≤ 0.021) and inclination (p ≤ 0.039) all increased significantly during testing in both groups. There were no significant differences for the group-wise comparisons at the cycle points defined in the methods (p ≥ 0.182). No significant differences were detected between groups for cycles to failure and failure load (p = 0.873).

INTERPRETATION

Bidirectional screw alignment does not lead to significant advantages compared to pure monoaxial if all three axial screws are evenly distributed over the osteotomy geometry. The triple pelvis innominate osteotomy is susceptible to changes in anteversion, inclination and medialisation under partial weight-bearing. Cautious rehabilitation protocols are recommended.

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.

Comparison of Percutaneous Screw Fixation to Open Reduction and Internal Fixation in Acetabular Fractures: A Matched Pair Study Regarding the Short-Term Rate of Conversion to Total Hip Arthroplasty and Functional Outcomes

Closed reduction and percutaneous internal fixation (CRPIF) for acetabular fractures was introduced as a less invasive alternative to open reduction and internal fixation (ORIF) for moderately displaced fractures. Currently, comparisons of ORIF and CRPIF outcomes are rare. Twenty-three patients treated with CRPIF were matched with patients treated with ORIF based on sex, age, and fracture classification. Surgery-dependent and -independent factors of the in-hospital stay, the conversion rate to total hip arthroplasty (THA), and quality of life were assessed. The ORIF group had a higher preoperative fracture step (p = 0.04) and gull wing sign (p = 0.003) compared with the CRPIF group. Postoperatively, the gap and step size were not significantly different between the groups (p > 0.05). CRPIF required less time (p < 0.0001) and transfusions (p = 0.009) and showed fewer complications (p = 0.0287). Four patients were converted to THA (CRPIF, n = 1; ORIF, n = 3; p = 0.155) because of posttraumatic osteoarthritis. Functional outcomes and pain were similar in both groups (p > 0.05). The present study revealed less blood loss and a lesser extent of reduction in patients treated with CRPIF than in those treated with ORIF. The rates of conversion to THA and functional outcomes did not differ between CRPIF and ORIF. CRPIF appeared to be a valuable treatment option for selected patients.

Primary stability of multi-hole cups compared to plate osteosynthesis in osteoporotic anterior column and posterior hemi-transverse acetabular fractures—A biomechanical comparison

Introduction

Acetabular fractures pose high demands on the surgeon and in the case of osteosynthetic treatment, anatomical reconstruction has the highest priority to achieve a good outcome. However, especially in older patients with poor bone quality, even anatomical reconstruction is no guarantee for a good clinical outcome and may nevertheless end in early osteoarthritis. Primary arthroplasty therefore has an increasing importance in the treatment of these patients. The aim of this study was to biomechanically compare fracture gap displacement and failure load as an assessment measure of the primary stability of conventional plate osteosynthesis with the treatment using a sole multi-hole cup for acetabular fractures.

Methods

Six hemi-pelvises each with anterior column and posterior hemi-transverse (ACPHT) fracture were treated with either plate osteosynthesis or a multi-hole cup. The tests were carried out in a standardised test set-up with cyclic loading in various stages between 150 N and 2500 N. The fracture gap displacement was recorded with optical 3D measuring and the failure load was determined after the cyclic measurement.

Results

With increasing force, the fracture gap displacement increased in both procedures. In each group there was one treatment which failed at the cyclic loading test and a bone fragment was broken out. The primary stability in arthroplasty was comparable to that of the standard osteosynthesis.

Conclusions

The results found seem promising that the primary arthroplasty with a sole multi-hole cup and corresponding screw fixation achieves an initial stability comparable to osteosynthesis for typical ACPHT fractures. However, further clinical studies are needed to prove that the cups heal solidly into the bone.

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.

The pectineal ligament is a secondary stabilizer in anterior pelvic ring fractures - a biomechanical study

BACKGROUND

There is ongoing discussion whether operative fixation of partially stable lateral compression fractures of the pelvis is beneficial for the patient. Recent studies suggest that the pectineal ligament may act as a secondary stabilizer of the anterior pelvis ring. The purpose of this study was to investigate the influence of the pectineal ligament's integrity on the biomechanical stability and displacement in anterior pelvic ring fractures.

METHODS

In a biomechanical setup, a cyclic loading protocol was applied with sinusoidal axial force from 100 to 500 N on cadaver hemipelves with soft tissues (n = 5). After testing the native specimens ("No fracture"), increasing degrees of injury were created on the samples: 1. an osseous defect to the pubic ramus ("Bone #"), 2. cutting of all soft tissues including obturator membrane except for the pectineal ligament intact ("ObtM #"), 3. cutting of the pectineal ligament ("PectL #") - with the loading protocol being applied to each sample at each state of injury. Fracture motion and vertical displacement were measured using a digital image correlation system and opto-metric analysis.

RESULTS

No failure of the constructs was observed. Creating a pubic ramus fracture (p = 0.042) and cutting the pectineal ligament (p = 0.042) each significantly increased relative fracture movement. The mean change in absolute movement was 0.067 mm (range, 0.02 mm to 0.19 mm) for ObtM # and 0.648 mm (range, 0.07 mm to 2.93 mm), for PectL # in relation to Bone # (p = 0.043). Also for absolute vertical movement, there was a significant change when the pectineal ligament was cut (p = 0.043), while there was no such effect with cutting all other soft tissues including the obturator membrane.

CONCLUSIONS

Based on the findings of this in vitro study, the pectineal ligament significantly contributes to the stability of the anterior pelvic ring. An intact pectineal ligament reduces fracture movement in presence of a pubic ramus fracture.

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.

Surgical Drill Guide for Insertion of an Infra-Acetabular Screw Based on an Anatomically Precontoured Plate System: A Cadaveric Study

Purpose

Due to the anatomic structure of the pelvis, free-hand placement of screws in the acetabular fracture management can be difficult. Infra-acetabular screw fixation increases acetabular stability by distal fixation of the cup. Aim of this cadaveric study is to investigate if a plate-referenced drill guide can provide save placement of an infra-acetabular screw over a precontoured suprapectineal quadrilateral buttress plate (SQBP).

Methods

We constructed a drill guide for an infra-acetabular screw based on the surface of an anatomically precontoured SQBP. A total of 12 adult cadaveric acetabular specimens were used for drill guide-assisted placement of the infra-acetabular screw. The drill guide contains a radiopaque spiral to allow longitudinal fine adjustment of the SQBP along the pelvic brim to assure correct position of the plate-drill-guide construct in relation to the Koehler's teardrop. After screw placement, we conducted a computed tomography (CT) scan of all specimens to assess the actual position of the screw in relation of the infra-acetabular corridor and the acetabular joint surface.

Results

The position of the screw was within the infra-acetabular corridor in all cases. We did not see any intra-articular or intrapelvic screw penetration. The mean distance of the centerline of the screw to the medial border of the infra-acetabular corridor was 3.35 mm. The secure distance to the virtual surface of the femoral head to was 7.3 mm.

Conclusions

A plate-referenced drill guide can provide safe placement of an infra-acetabular screw for treatment of acetabular fractures. Radiographic fine adjustment is necessary to access the optimal entry point.

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 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.

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.

A novel anatomically pre-contoured side-specific titanium plate versus the reconstruction plate for quadrilateral plate fractures of the acetabulum: a propensity-matched cohort study

Background

Surgical treatment of acetabular fractures involving a quadrilateral plate is a challenge to orthopedic surgeons. We have developed a novel fixation technique using a specially shaped reconstruction plate combined with several buttress screws of a quadrilateral plate which was also called a dynamic anterior plate-screw system for quadrilateral plate (DAPSQ) to treat acetabular fractures involving quadrilateral plate since 2005 (RP group). And the long-term follow-up results have confirmed the effectiveness and safety of this technique. After 2016, standardized titanium plate (STP group) of DAPSQ have been designed and applied. The aim of the study was to compare the clinical efficacy of anatomical plate and the reconstruction plate of DAPSQ in the treatment of quadrilateral plate fractures.

Methods

We led a propensity-matched cohort study of quadrilateral plate fractures. Twenty-two patients were included in the STP group during the inclusion period (2016–2018) and were matched to 22 cases in our database of the RP group (2008–2016). The primary outcome measures were the quality of reduction and functional outcomes. Intraoperative conditions were also compared.

Results

Of these 22 consecutive patients in the STP group, the mean age was 46.7 years and the most common fracture pattern was a both-column fracture (12 cases, 54.5%) according to Letournel-Judet classification. The mean follow-up period was 23.1 months (range 12–37). There were no significant differences between the two groups with regard to the quality of reduction using the Matta radiological criteria and functional outcomes evaluated by the modified Merle d’Aubigné score (P > 0.05). Compared with the RP group, the STP group had a shorter operation time (245.1 min vs. 286.8 min, P = 0.020), less intraoperative blood loss (1136.4 mL vs. 1777.3 mL, P = 0.014), and transfusion (780.9 vs. 1256.8 mL, P = 0.035). The complication rate was 18.2% in the STP group, and there was no significant difference compared with the RP group (36.4%) (P > 0.05). None of the cases in the two groups had quadrilateral screws entering the hip or implant failure.

Conclusions

The fixation of standardized titanium plate in quadrilateral plate fractures showed a similar result to the reconstruction plate, in terms of quality of reduction and functional outcome. The standardized titanium plate of DAPSQ has the advantages of a short operation time, less intraoperative bleeding, and blood transfusion, and it is worth further promotion and research.

Minimally invasive surgical treatment of minimally displaced acetabular fractures does not improve pain, mobility or quality of life compared to conservative treatment: a matched-pair analysis of 50 patients

Background

Currently available procedures for the treatment of minimally displaced acetabular fractures include conservative treatment and minimally invasive percutaneous screw fixation. Screw fixation of acetabular fractures allows patients’ early full-weight bearing due to improved biomechanic stability. Can the range of motion, pain and mobility and quality of life in patients with acetabular fractures be improved by minimally invasive screw fixation, compared to conservative treatment in the long term?

Methods

Patients treated for a minimally displaced acetabular fracture, either conservatively or by closed reduction percutaneous screw fixation, in the period from 2001 to 2013 were included in this retrospective study. Minimal displacement was considered to be less than 5 mm. As well as the collection and analysis of baseline data, Harris Hip Score, Merle d’Aubigné score and Short Form 12 (SF-12) questionnaire data were recorded in the context of a clinical study. To better account for confounding factors, patients of each group were matched. The matched-pair criteria included age, BMI, Letournel fracture classification and the presence of associated injuries.

Results

Twenty-five patients from each group were matched. On the Harris Hip Score, conservatively treated patients obtained 96 points (52–100, SD 17) vs. 89 points (45–100, SD 17, p = 0.624). On the Merle d’Aubigné score, conservatively treated patients obtained 17 points (10–18, SD 2) vs. 17 points (11–18, SD 2, p = 0.342).

Patients with acetabular fractures treated by minimally invasive screw fixation did not result in improved quality of life, measured by SF-12 questionnaire, compared to conservatively treated patients (PCS 47, SD 9 vs. 44, SD 10; p = 0.294 and MCS 51, SD 7 vs. 53, SD 7; p = 0.795).

Conclusions

The clinical results of the two groups revealed no statistically significant differences. From the data, it cannot be deduced that minimally invasive surgical therapy is superior to conservative treatment of minimally displaced acetabular fractures. Prospective randomised studies are recommended to allow reliable evaluation of both treatment options.

Trial registration

Retrospectively registered

Cannulated iliac screw fixation combined with reconstruction plate fixation for Day type II crescent pelvic fractures

Objective

Method

Results

Conclusion

Antegrade versus retrograde screw fixation of anterior column acetabular fractures: a biomechanical in vitro study

BACKGROUND

To compare the mechanical strength of antegrade versus retrograde lag screw fixation of anterior column acetabular fractures.

METHODS

Standardised anterior column fractures were created in synthetic pelvis models and stabilised by either antegrade (ANTE, n = 4) or retrograde (RETRO, n = 4) anterior column screw fixation. In a validated setup, a cyclic loading protocol was applied with increasing axial force (750 cycles, 250-750 N) followed by load to failure. Construct survival, energy absorbed, construct stiffness, and load to failure were assessed. Descriptive and opto-metric methods were used to describe the mode of failure.

RESULTS

All constructs failed with loads below 1500 N. With regard to energy absorbed until failure, the ANTE group resisted to 3.763 × 10⁵ N*cycles (range 3.760 × 10⁵-3.763 × 10⁵) and the RETRO group to 3.762 × 10⁵ N*cycles (range 3.761 × 10⁵-3.765 × 10⁵; p = 1.0). The load to failure was 1254 N (range 977-1299) in the ANTE group and 1234 N (range 1087-1456) in the RETRO group (p = 1.0). Construct stiffness with 250 N was not different between the two groups (ANTE 192 N/mm vs. RETRO 215 N/mm, p = 0.486). In all samples, the mode of failure was a transiliac fracture with screw breakout due to rotation of the pubic fragment around the axis of the screw with a range of rotational motion [ROM] during cyclic testing of 0.96° in one ANTE sample and 0.82° in one RETRO sample for 750 N, and ROM at failure of 2.53° in one ANTE sample and 2.23° in one RETRO sample. There was some plastic deformation of the screws in all cases but no breakage.

CONCLUSIONS

In this in vitro mechanical study, antegrade screw fixation of an anterior column acetabular fracture was not different in construct survival, load to failure, stiffness, and mode of failure when compared to retrograde screw fixation.