Acetabular fractures: what radiologists should know and how 3D CT can aid classification

Double Trouble: Exploring Bilateral Acetabular Fractures in a Trauma Patient

Bilateral acetabular fractures, though rare, pose significant challenges in both diagnosis and management due to their association with high-energy trauma and the potential for long-term disability. This case report presents the clinical course of a 27-year-old female who presented to our department after a motorcycle accident with bilateral acetabular fractures. Initial assessment revealed nondisplaced bilateral acetabular fractures, along with associated injuries including a right ulnar styloid fracture. Further evaluation via 3D CT scan delineated associated column fractures on the right and posterior + anterior wall fractures on the left, classified according to the Letournel and Judet system. Notably, this specific combination of acetabular fractures has not been documented in existing literature as per our investigation. The surgical intervention involved an anterior intrapelvic approach for open reduction and internal fixation (ORIF) of the right acetabulum, while the left acetabulum was managed conservatively. Postoperatively, the patient is scheduled for non-weightbearing activity until radiographic evidence of fracture healing is observed. This case underscores the importance of tailored surgical approaches and comprehensive management strategies in optimizing outcomes for patients with bilateral acetabular fractures.

Traumatic bilateral acetabular fracture secondary to high-energy trauma in healthy adults

BACKGROUND

Bilateral acetabular fracture is a very rare presentation among the trauma patients, as the pattern and the degree of the forces required to fracture both acetabula is very unique. The primary purpose of this study is to report a series of adult patients presenting with post-traumatic bilateral acetabular fracture without any history of pathological or metabolic bone disease.

PATIENTS AND METHODS

In this retrospective study, 18 cases of traumatic bilateral acetabular fracture were included. There was predominance of both column (four patients on left and six on right) followed by anterior column (two patients left and four on right) and posterior wall (three patients left and right). They were treated surgically through open reduction and internal fixation. All cases were followed up for at least 13 months. Matta's criteria were used for radiological evaluation on plain radiographs. Functional outcome was evaluated using the Merle d'Aubigne and postel score at final follow-up.

RESULTS

No patients were lost during the follow-up period; there was one case of surgical site infection. There were three cases of postoperative osteoarthritis, one case of heterotrophic ossification, one case of persistent sciatic nerve palsy and one case of lateral femoral cutaneous nerve palsy. The radiological evaluation according to Matta's criteria revealed anatomic reduction in 12 patients, imperfect reduction in three patients while other three patients had poor reduction. According to modified Merle d'Aubigne and Postel score, 10 cases were rated as excellent, five cases as good and three cases presented fair (one case) to poor (two cases) results.

CONCLUSION

We report an unusual case series of bilateral acetabular fracture successfully managed surgically with good clinical outcome. With the increasing incidence of route traffic accidents, such cases would probably be recurrent in the upcoming years.

The Association between Hip Joint Morphology and Posterior Wall Fracture: Analysis of Radiologic Parameters in Computed Tomography

Although numerous radiologic parameters of abnormal hip joint morphology are utilized in practice, studies on the relation of these parameters to acetabular fractures are limited. This study hypothesized that certain morphological features of hip joints are associated with acetabular posterior wall (PW) fracture patterns and aimed to identify morphological characteristics predictive of acetabular PW fracture. The records of 107 consecutive patients, who were diagnosed with acetabular fractures in a level I trauma center from August 2017 to April 2021, were initially reviewed. After excluding patients who lacked proper radiographic evaluation and had previous surgery or concomitant injury on the ipsilateral lower limb, a total of 99 patients were analyzed to investigate the morphological characteristics of the hip joint, measured in computed tomography, associated with acetabular posterior wall fracture. We included patient demographics, acetabular index (AI), sharp angle, acetabular depth-to-width ratio (AD/WR), center-edge angle (CEA), head-neck offset ratio (HNOR), acetabular head index (AHI), anterior acetabular sector angle (AASA), posterior acetabular sector angle (PASA), and acetabular version angle (AVA) in the univariate and multivariate analyses. The injury mechanism (p = 0.001) and AD/WR (p = 0.021) were predictors of PW fracture in the univariate analysis. In the multivariable analysis, injury mechanism (p = 0.011), AI (coefficient B = 0.320; Exp (B) = 1.377; p = 0.017), and AD/WR (coefficient B = 33.047; Exp (B) = 2.250 × 1014; p = 0.028) were significant predictors of PW fracture. This study highlights the importance of morphological factors, such as a larger AI and AD/WR, that may influence joint stress distribution, resulting in acetabular PW fracture. Understanding these pathomechanisms may protect the hip joint and prevent future injuries through the early identification and treatment of pathological conditions.

Acetabular fractures in elderly

BACKGROUND

This study aimed to determine characteristics of acetabular fractures in the elderly by evaluating clinical course and computed tomography-based radiological features between low- and high-energy acetabular fractures.

METHODS

We reviewed 178 consecutive patients with acetabular fractures aged ≥60 years from six centers. Low-energy fractures (group 1) were identified in 23 (12.9%) patients and high-energy fractures (group 2) in 155 (87.1%) patients. We compared demographics, radiological findings, and clinical course between the groups.

RESULTS

Average age (70.6 vs. 67.8 years, p = 0.046) and ratio of females (47.8% vs. 23.2%, p = 0.021) were significantly higher in group 1 than in group 2. The Charlson comorbidity index was also higher in group 1, but no other demographics showed difference. More patients in group 2 than in group 1 underwent surgery (91.6% vs. 73.9%); however, more in group 1 underwent minimally invasive surgery (17.4% vs 4.5%). Anterior column-associated fracture patterns occurred in 91.4% and 38.7% of cases in groups 1 and 2, respectively. Most fractures were displaced (>2 mm); 68% of which were comminuted. Furthermore, 24.2% of the fractures had superior dome impaction, whereas 23.0% were associated with posterior wall impaction.

CONCLUSIONS

Patients who sustained low-energy acetabular fractures were mostly women, were older, and had more comorbidities. Radiological findings of low-energy acetabular fractures showed anterior column involvement associated with injury to the quadrilateral surface. Additionally, it was observed to be commonly combined with comminution and impacted fragments.

Development and validation of a deep learning-based model to distinguish acetabular fractures on pelvic anteroposterior radiographs

Objective: To develop and test a deep learning (DL) model to distinguish acetabular fractures (AFs) on pelvic anteroposterior radiographs (PARs) and compare its performance to that of clinicians. Materials and methods: A total of 1,120 patients from a big level-I trauma center were enrolled and allocated at a 3:1 ratio for the DL model's development and internal test. Another 86 patients from two independent hospitals were collected for external validation. A DL model for identifying AFs was constructed based on DenseNet. AFs were classified into types A, B, and C according to the three-column classification theory. Ten clinicians were recruited for AF detection. A potential misdiagnosed case (PMC) was defined based on clinicians' detection results. The detection performance of the clinicians and DL model were evaluated and compared. The detection performance of different subtypes using DL was assessed using the area under the receiver operating characteristic curve (AUC). Results: The means of 10 clinicians' sensitivity, specificity, and accuracy to identify AFs were 0.750/0.735, 0.909/0.909, and 0.829/0.822, in the internal test/external validation set, respectively. The sensitivity, specificity, and accuracy of the DL detection model were 0.926/0.872, 0.978/0.988, and 0.952/0.930, respectively. The DL model identified type A fractures with an AUC of 0.963 [95% confidence interval (CI): 0.927-0.985]/0.950 (95% CI: 0.867-0.989); type B fractures with an AUC of 0.991 (95% CI: 0.967-0.999)/0.989 (95% CI: 0.930-1.000); and type C fractures with an AUC of 1.000 (95% CI: 0.975-1.000)/1.000 (95% CI: 0.897-1.000) in the test/validation set. The DL model correctly recognized 56.5% (26/46) of PMCs. Conclusion: A DL model for distinguishing AFs on PARs is feasible. In this study, the DL model achieved a diagnostic performance comparable to or even superior to that of clinicians.

Is the T-shaped acetabular fracture really likes a "T"? A study based on three-dimensional fracture mapping

OBJECTIVES

To explore the morphological pattern of T-shaped acetabular fractures (T-SAFs) by mapping the fracture line using 3D software.

MATERIAL AND METHODS

We retrospectively reviewed 1298 consecutive patients with acetabular fractures, and a total of 56 T-SAF patients were enrolled. After the simulated reduction of each fracture in the software, the fracture lines of all patients were overlaid and plotted on a template. A frequency heat map was generated according to the differences in fracture line density distribution. According to the location of fracture lines, all cases were divided into three groups: posterior group, anterior group, extra-posterior group. In surgically treated patients, the surgical approach, fixation methods, and reduction quality were recorded or evaluated.

RESULTS

The transverse fracture line was sinuous without involving the acetabular roof, and the longitudinal fracture line sloped forward or backward along the edge of the acetabular fossa to split the obturator foramen. The anterior and posterior edges of the acetabular fossa, the transition zone of the acetabular roof and anterior wall, the transition zone of the superior pubic ramus and anterior wall, and the posterior wall near the greater sciatic notch were areas with high rates of fracture incidence. The posterior group included 26 patients (46.4%) and the distribution of fracture lines resembled a "T" or "Y". The anterior group included 25 patients (44.6%) and the distribution of fracture lines resembled a "7″. The extra-posterior group included 5 patients (8.9%) and the fracture lines run through the ischial body. The surgical strategies vary among different groups of T-SAF patients.

CONCLUSION

Our findings shed light on the characteristics of fracture lines for T-SAFs and provide a reference for surgical treatment strategies.

Displacement Pattern of Anterior and Posterior Column Fragments in Both-Column Acetabular Fractures: A 3D Reconstruction-Based Study

Background

Few studies have been conducted to examine the displacement characteristics of both-column acetabular fractures (BCAFs). The goal of this study was to investigate the displacement pattern of anterior column (AC) and posterior column (PC) fragments in BCAFs using 3D virtual software.

Materials and Methods

BCAFs were retrospectively reviewed, and 81 patients were enrolled. Computed tomography (CT) images were imported into Mimics software. A 3D model of each pelvis was generated. Four marked points and the rotation angle of each of the injured ACs and PCs were identified. The fracture fragments were reduced virtually using the software, and the change in coordinates of the marked points after reduction was recorded while the rotation angle was measured. The measurements of positional and directional displacement were analysed using the Mann–Whitney U test and the binomial test, respectively.

Results

There was a propensity for AC fragments to shift superomedially and to rotate externally (p < 0.001). Additionally, the posteroinferior fracture area of AC fragments showed the greatest displacement (p < 0.05). PC fragments moved superomedially (p < 0.001) and moved more at the proximal end than the distal end (p < 0.001). PC displacement was always accompanied by internal rotation (p < 0.001). Greater AC displacement was observed in the fracture area further away from the acetabulum (p < 0.05). Greater rotation was observed for the AC than the PC (p < 0.001).

Conclusion

After a BCAF occurs, there are regular patterns regarding the direction and distance of AC and PC fragment displacement. Information on these patterns may provide insight into the injury mechanism and fracture morphology and facilitate surgical decision-making for orthopaedic trauma surgeons.

Quantitative Three-Dimensional Measurements of Acetabular Fracture Displacement Could Be Predictive for Native Hip Survivorship

This study aims to develop a three-dimensional (3D) measurement for acetabular fracture displacement, determine the inter- and intra-observer variability, and correlate the measurement with clinical outcome. Three-dimensional models were created for 100 patients surgically treated for acetabular fractures. The ‘3D gap area’, the 3D surface between all the fracture fragments, was developed. The association between the 3D gap area and the risk of conversion to a total hip arthroplasty (THA) was determined by an ROC curve and a Cox regression analysis. The 3D gap area had an excellent inter-observer and intra-observer reliability. The preoperative median 3D gap area for patients without and with a THA was 1731 mm2 versus 2237 mm2. The median postoperative 3D gap area was 640 mm2 versus 845 mm2. The area under the curve was 0.63. The Cox regression analysis showed that a preoperative 3D gap area > 2103 mm2 and a postoperative 3D gap area > 1058 mm2 were independently associated with a 3.0 versus 2.4 times higher risk of conversion to a THA. A 3D assessment of acetabular fractures is feasible, reproducible, and correlates with clinical outcome. Three-dimensional measurements could be added to the current classification systems to quantify the level of fracture displacement and to assess operative results.

Fracture patterns in midshaft clavicle fractures

Current classifications of midshaft clavicle fractures are based on radiography. The aim of the study was to evaluate the fracture pattern of clavicle fractures using 3-dimensional computed tomography (3D CT). A retrospective analysis was performed on CT scans of 65 acute clavicle fractures. Using quantitative 3D CT reconstruction techniques, the fracture of the clavicle was virtually reduced. Based on these reconstructions, a group-based fracture heat map and small fragment heat map, and the location of the most common fracture line were determined. Also, the direction and amount of displacement were evaluated. Three fracture patterns could be distinguished. The primary fracture line in type 1 is going from posteromedial to anterolateral and located between 50% and 68% of the clavicle’s length. In type 2, a transverse fracture line is located around 55%, and in type 3, a superolateral to inferomedial line is located between 47% and 56%. Wedged fracture fragments can be seen in types 1 and 2 and are mainly situated inferiorly. The displacement is similar in all types, but the main direction of displacement is specific for the different types (posterior, anterior, inferior). We can conclude that several fracture patterns can be seen in clavicle fractures. Most fractures are located laterally at the midshaft of the clavicle. Wedged segments are mainly located inferiorly, and at the posterior part of the clavicle, no comminution is ever seen. The direction of displacement depends on the fracture pattern.

Does 3D-Assisted Acetabular Fracture Surgery Improve Surgical Outcome and Physical Functioning?-A Systematic Review

Three-dimensional technology is increasingly being used in acetabular fracture treatment. No systematic reviews are available about the added clinical value of 3D-assisted acetabular fracture surgery compared to conventional surgery. Therefore, this study aimed to investigate whether 3D-assisted acetabular fracture surgery compared to conventional surgery improves surgical outcomes in terms of operation time, intraoperative blood loss, intraoperative fluoroscopy usage, complications, and postoperative fracture reduction, and whether it improves physical functioning. Pubmed and Embase databases were searched for articles on 3D technologies in acetabular fracture surgery, published between 2010 and February 2021. The McMaster critical review form was used to assess the methodological quality. Differences between 3D-assisted and conventional surgery were evaluated using the weighted mean and odds ratios. Nineteen studies were included. Three-dimensional-assisted surgery resulted in significantly shorter operation times (162.5 ± 79.0 versus 296.4 ± 56.0 min), less blood loss (697.9 ± 235.7 mL versus 1097.2 ± 415.5 mL), and less fluoroscopy usage (9.3 ± 5.9 versus 22.5 ± 20.4 times). The odds ratios of complications and fracture reduction were 0.5 and 0.4 for functional outcome in favour of 3D-assisted surgery, respectively. Three-dimensional-assisted surgery reduces operation time, intraoperative blood loss, fluoroscopy usage, and complications. Evidence for the improvement of fracture reduction and functional outcomes is limited.

Ankle CT scan allows better management of posterior malleolus fractures than X-rays

PURPOSE

Undiagnosed and undertreated posterior malleolus fractures lead to early ankle instability and arthritis. A preoperative CT scan could improve the management of those fractures. This study assessed the benefits of a systematic ankle CT scanner to diagnose and manage posterior malleolus fracture.

METHODS

A monocentric retrospective cohort study was conducted. Sixty consecutive patients with bimalleolar fractures were operated and underwent a preoperative CT scan. The mean age was 50.0 years old (18.6 years old) with a mean body mass index of 20.3 (kg/m²) (11.4 kg/m²) and 71.7% (43/60) of women. The primary outcome was the rate of posterior malleolus fragment diagnosed on X-rays and on CT scan. Secondly, interobserver and interobserver's agreement were compared between conventional X-rays and CT scan.

RESULTS

Thirty-five (58.3%) posterior fragment fractures were observed on X-rays and 53 (88.3%) on the preoperative CT scan (p < 0.01). The intraobserver reproducibility for X-rays was low (0.02 [- 0.23; 0.27]) and moderate for CT scan (0.45 [0.0; 0.84]). The interobserver reproducibility for X-rays was moderate (0.39 [0.15; 0.60]) and excellent for CT scan (0.78 [0.0; 1.0]).

CONCLUSION

A wide proportion of bimalleolar fractures are associated with posterior malleolus fractures and undiagnosed with standard X-rays. We advocate a systematic preoperative CT scan in the management of bimalleolar fractures.

LEVEL OF EVIDENCE

Level IV, retrospective cohort study.

TRIAL REGISTRATION NUMBER

2218999v0, date of registration: 11/08/2020 (retrospectively registered).

A Systematic Review and Meta-Analysis of 3D Printing Technology for the Treatment of Acetabular Fractures

Purpose

Three-dimensional (3D) printing technology has been widely used in orthopedics surgery. However, its efficacy in acetabular fractures remains unclear. The aim of this systematic review and meta-analysis was to examine the effect of using 3D printing technology in the surgery for acetabular fractures.

Methods

The systematic review was performed following the PRISMA guidelines. Four major electronic databases were searched (inception to February 2021). Studies were screened using a priori criteria. Data from each study were extracted by two independent reviewers and organized using a standardized table. Data were pooled and presented in forest plots.

Results

Thirteen studies were included in the final analysis. Four were prospective randomized trials, and nine used a retrospective comparative design. The patients aged between 32.1 (SD 14.6) years and 51.9 (SD 18.9) years. Based on the pooled analyses, overall, 3D printing-assisted surgery decreased operation time by 38.8 minutes (95% CI: -54.9, -22.8), intraoperative blood loss by 259.7 ml (95% CI: -394.6, -124.9), instrumentation time by 34.1 minutes (95% CI: -49.0, -19.1). Traditional surgery was less likely to achieve good/excellent function of hip (RR, 0.53; 95% CI: 0.34, 0.82) and more likely to have complications than 3D printing-assisted surgery (RR, 1.19; 95% CI: 1.07, 1.33).

Conclusions

3D printing technology demonstrated efficacy in the treatment of acetabular fractures. It may improve surgery-related and clinical outcomes. More prospective studies using a rigorous design (e.g., randomized trial with blinding) are warranted to confirm the long-term effects of 3D printing technology in orthopedics surgeries.

Roof arc width: The novel calculation method for calculation of patient specific roof arc width in acetabular fractures

Purpose

Roof arc angle (RAA) is determined by measuring angle between a vertical line drawn from center of the acetabulum towards the acetabular dome and a second line drawn from center of acetabulum to the fracture through the acetabulum. Joel and Matta demonstrated that when roof arc angle was less than 45° on Pelvic AP and Judet's views, the fracture line is considered to be passing through the weight-bearing dome and require surgical fixation. The main purpose of the study is to calculate patient-specific angle and width for the better evaluation and management of acetabular fractures.

Methods

Radiographs of normal hips were retrieved from electronic data and parameters were calculated. Two observers calculated the parameters at two different intervals. Pearson correlation formula was used to find a correlation between groups.

Results

Fifty radiographs of 28 patients were reviewed. The mean age of patients was 75.58 years ±13.28. The radius of the acetabulum, the radiographic measurement of sector width for 45° angulation at the roof, and the mathematical calculation for roof arc for 45° angle had significant positive correlation for both observers at two different occasions.

Conclusions

The measured roof arc width ranges from a minimum of 16.20 mm-31.50 mm and the calculated arc width for a 45-degree angle varies from a minimum of 15 mm-25.56 mm. These values are higher than the described values of 10 mm equals to 45 degrees. Hence, the values measured in this study should be considered for decision making in the management of acetabular fractures.

Efficacy of repeated intravenous tranexamic acid in reducing perioperative bleeding of acetabular fractures

BACKGROUND

Application of tranexamic acid (TXA) in the treatment of acetabular fractures could reduce intraoperative and postoperative blood loss.

OBJECTIVE

To investigate the effect of single and repeated intravenous infusion of TXA on blood loss of acetabular fractures.

METHODS

120 patients with acetabular fractures admitted to our hospital from January 2017 to September 2020 were retrospectively divided into three groups: Patients accepted 1g TXA at preoperative 30 minutes were defined as single TXA group (n = 40); Patients accepted 1g TXA at preoperative 30 minutes and 1g TXA at 3 hours after the start of surgery were defined as repeated TXA group (n = 40); Patients accepted normal saline at preoperative 30 minutes were defined as control group (n = 40).

RESULTS

The total blood loss in single TXA group and repeated TXA group were significantly lower than control group, and the total blood loss in the repeated TXA group was significantly lower than single TXA group (P <  0.05). The hidden blood loss from surgery to postoperative 1 day in repeated TXA group was significantly lower than single TXA group and the control group(P <  0.05). No significant differences were observed in the operative time, postoperative transfusion rate and thrombosis rate among the three groups (P >  0.05).

CONCLUSION

Repeated TXA is more recommended during acetabular fracture surgery since it can reduce the total blood loss without increasing the operative time, postoperative transfusion rate and thrombosis rate compared with single TXA.

Advantages of preoperative planning using computed tomography scan for treatment of malleolar ankle fractures

Malleolar ankle fractures have been classified using plain radiographs, and there is no consensus regarding the role of computed tomography (CT) scans in preoperative planning. We analyzed critical aspects, such as limits of standard radiographs, types of injury, classification methods and cost/benefit evaluations. CT scans allow a 3D analysis of the fracture to be obtained and consequently assess the indication for surgical procedure, surgical access and the type of fixation devices required. This exam is useful for detecting lesions that may go unnoticed on radiographs and will help surgeons to clarify the pathoanatomy of ankle fractures. According to Arbeitsgemeinschaft fur Osteosynthesefragen/ Orthopaedic Trauma Association (AO/OTA) classification, CT scan is recommended in medial malleolar fractures with vertical rim, type 44B fractures with posterior malleolar involvement and all type 44C fractures (according to AO/OTA). Also Tillaux-Chaput fractures (43-B1 according to AO/OTA), malleolar fractures in the presence of distal tibial fractures (43 according to AO/OTA) and distal tibia fractures in adolescents should be studied with CT scans.

Three-dimensional finite element analysis with different internal fixation methods through the anterior approach

BACKGROUND

With the modernization of society and transportation in the last decades in China, the incidence of high-energy trauma increased sharply in China, including that of acetabular fractures.

AIM

To establish different finite element models for acetabular posterior column fractures involving the quadrilateral area of the acetabulum.

METHODS

The three-dimensional models of the normal and fractured pelvis and the five internal fixations were established using the computed tomography data of the pelvis of a living volunteer. After the vertebral body model was inserted in the way of origin matching and all cancellous bones were copied using the duplicated cancellous bone model as the subtractive entity, the Boolean operation was performed on the pelvis model to obtain the model of the complete pelvis cortical and cancellous bones.

RESULTS

In the standing position, the maximum stress was 46.21 MPa. In the sitting position, the sacrum bore the simulated gravity load at the upper end. When comparing the five fixations, there were no significant differences in the stress mean values among groups (sitting: P = 0.9794; standing: P = 0.9741). In terms of displacement, the average displacement of the internal iliac plate group was smaller than that of the spring plate group (P = 0.002), and no differences were observed between the other pairs of groups (all P > 0.05). In the standing position, there were no significant differences in the mean value of displacement among the groups (P = 0.2985). It can be seen from the stress nephogram of the internal fixations in different positions that the stress of the internal fixation was mainly concentrated in the fracture segment.

CONCLUSION

There were no significant differences among the fixations for acetabular posterior column fractures involving the quadrilateral area of the acetabulum.

The management of osteoporotic acetabular fractures: Current methods and future developments

Acetabular fractures in the elderly are challenging. Management is complicated by patients' poor physiological status and osteoporotic bone. Analysis of the management of these patients must be separated from the treatment of younger patients. Conservative management continues to have a role in patients who sustain fractures that are non-displaced and are considered stable with weight bearing mobilisation, and in those patients considered too medically frail to undergo surgical intervention. The mainstay of current surgical intervention is open reduction and internal fixation (ORIF) and variations of ORIF and total hip arthroplasty (THA), or fix and replace. Fix and replace is being increasingly favoured in those patients who display poor prognostic factors for long term joint survival after ORIF. Percutaneous fixation has the theoretical benefits of minimally invasive surgery and the potential to make any subsequent THA less complicated. However, it requires specialised fluoroscopic skills and is not suitable for all fracture patterns. There are a number of developments being reported. The use of a reinforcement ring and THA in has been reported in a number of centres, as has the use of trabecular metal acetabular implants. A coned hemi pelvic prosthesis and THA has been described in our centre, with promising early results. The potential for 3D printing to improve preoperative planning and reduce intra-operative time is also being explored. The aim of this review is to provide a summary of the literature supporting current and future treatment methods, tips on reduction techniques and an overview of the treatment algorithm of these patients in our unit.

CT-Based 3D Printing of the Glenoid Prior to Shoulder Arthroplasty: Bony Morphology and Model Evaluation

To demonstrate the 3D printed appearance of glenoid morphologies relevant to shoulder replacement surgery and to evaluate the benefits of printed models of the glenoid with regard to surgical planning. A retrospective review of patients referred for shoulder CT was performed, leading to a cohort of nine patients without arthroplasty hardware and exhibiting glenoid changes relevant to shoulder arthroplasty planning. Thin slice CT images were used to create both humerus-subtracted volume renderings of the glenoid, as well as 3D surface models of the glenoid, and 11 printed models were created. Volume renderings, surface models, and printed models were reviewed by a musculoskeletal radiologist for accuracy. Four fellowship-trained orthopaedic surgeons specializing in shoulder surgery reviewed each case individually as follows: First, the source CT images were reviewed, and a score for the clarity of the bony morphologies relevant to shoulder arthroplasty surgery was given. The volume rendering was reviewed, and the clarity was again scored. Finally, the printed model was reviewed, and the clarity again scored. Each printed model was also scored for morphologic complexity, expected usefulness of the printed model, and physical properties of the model. Mann-Whitney-Wilcoxon signed rank tests of the clarity scores were calculated, and the Spearman's ρ correlation coefficient between complexity and usefulness scores was computed. Printed models demonstrated a range of glenoid bony changes including osteophytes, glenoid bone loss, retroversion, and biconcavity. Surgeons rated the glenoid morphology as more clear after review of humerus-subtracted volume rendering, compared with review of the source CT images (p = 0.00903). Clarity was also better with 3D printed models compared to CT (p = 0.00903) and better with 3D printed models compared to humerus-subtracted volume rendering (p = 0. 00879). The expected usefulness of printed models demonstrated a positive correlation with morphologic complexity, with Spearman's ρ 0.73 (p = 0.0108). 3D printing of the glenoid based on pre-operative CT provides a physical representation of patient anatomy. Printed models enabled shoulder surgeons to appreciate glenoid bony morphology more clearly compared to review of CT images or humerus-subtracted volume renderings. These models were more useful as glenoid complexity increased.

3D reconstructions, 4D imaging and postprocessing with CT in musculoskeletal disorders: Past, present and future

Three-dimensional (3D) imaging and post processing are common tasks used daily in many disciplines. The purpose of this article is to review the new postprocessing tools available. Although 3D imaging can be applied to all anatomical regions and used with all imaging techniques, its most varied and relevant applications are found with computed tomography (CT) data in musculoskeletal imaging. These new applications include global illumination rendering (GIR), unfolded rib reformations, subtracted CT angiography for bone analysis, dynamic studies, temporal subtraction and image fusion. In all of these tasks, registration and segmentation are two basic processes that affect the quality of the results. GIR simulates the complete interaction of photons with the scanned object, providing photorealistic volume rendering. Reformations to unfold the rib cage allow more accurate and faster diagnosis of rib lesions. Dynamic CT can be applied to cinematic joint evaluations a well as to perfusion and angiographic studies. Finally, more traditional techniques, such as minimum intensity projection, might find new applications for bone evaluation with the advent of ultra-high-resolution CT scanners. These tools can be used synergistically to provide morphologic, topographic and functional information and increase the versatility of CT.

Avascular necrosis of the femoral head after traumatic posterior hip dislocation with and without acetabular fracture

PURPOSE

Traumatic hip dislocation can be isolated or associated with acetabular fracture. Both injuries require emergency reduction of the dislocated hip. Avascular necrosis of the femoral head (AVN) is a potential complication that accompanies these severe injuries. Our objective is to identify the risk factors that cause AVN.

METHODS

We retrospectively analyzed 44 patients with traumatic hip dislocations (Group A) and patients with posterior fracture-dislocation of the acetabulum (Group B). The average follow-up was 5.38 years in Group A, 5.59 years in Group B. We used the Thompson-Epstein classification for hip dislocation and the Harris Hip Score (HHS) for evaluating final outcomes.

RESULTS

In Group A, we analyzed 21 patients with isolated posterior hip dislocation. We had one (4.76%) case of AVN. In Group B, we analyzed 23 patients with posterior acetabular fracture-dislocation. We had eight (34.78%) patients with AVN (p = 0.016, p < 0.05). With hip reduced 6-12 h after injury, we had AVN in one (4.34%) patient, with reduction 12-24 h, AVN was present in two (8.69%), while in hip reduction done after 24 h of injury, AVN was present in five (21.73%) patients (p = 0.030, p < 0.05).

CONCLUSION

An essential prerequisite for the prevention of AVN of the femoral head after hip dislocation is emergency hip reduction. In acetabular fracture-dislocation, emergency hip reduction, anatomical reduction of the acetabular fracture and early stable osteosynthesis are also important. Main factor affecting the development of AVN is late reduction of the hip.

Evaluation of Judet view radiographs accuracy in classification of acetabular fractures compared with three-dimensional computerized tomographic scan: a retrospective study

Background

In the current diagnostic procedure, generally, both plain radiographs and 3D-CT scans are used for the diagnosis of acetabular fractures. There is no consensus regarding the value of a three-dimensional computerized tomographic (3D-CT) scan alone in the classification of acetabular fractures. In this study, we compared the accuracy of 3D-CT scan and plain radiography through the evaluation of their agreement with the intraoperative surgeon’s classification.

Method

In a retrospective study, patients who were referred to our center with an acetabular fracture and underwent surgical treatment were included. The classification of acetabular fractures was performed once using Judet view plain radiographs and once using a 3D-CT scan by the corresponding one Experienced musculoskeletal radiologist one independent trauma fellowship-trained orthopaedic who routinely treat acetabular fractures and based on Letournel and Judet classification (17 and 23 years of experience respectively). Cohen’s kappa value was used for the assessment agreement between the two imaging modalities, as well as between the imaging modalities and intraoperative classification.

Results

Medical files of 152 patients with acetabular fracture were retrospectively reviewed. A kappa value of 0.236 was obtained as the agreement level between radiographs and intraoperative findings (p < 0.001). A kappa value of 0.943 was obtained as the agreement level between 3D-CT and intraoperative classification (p < 0.001). An agreement level of 0.264 was found between the Judet radiographs and 3D-CT scans (p < 0.001).

Conclusions

3D-CT scans are reliable enough in the classification of acetabular fractures, and plain radiographs could be omitted to avoid radiation exposure as well as to reduce the cost for patients who sustain acetabular fractures.

Comparison of three-dimensional and two-dimensional computed tomographies in the classification of acetabular fractures

PURPOSE

This study compared the accuracy and timeliness of two-dimensional computed tomography (2DCT) and three-dimensional computed tomography (3DCT) in the diagnosis of different types of acetabular fractures and by different groups of interpreters using the Letournel and Judet classification system.

METHODS

Twenty-five fractures cases, five each of five common types of acetabular fractures, were selected. Nineteen interpreters with different levels of experience (ten graduate trainees and nine radiologists) individually classified the fractures using multiplanar 2D and standardized 3DCT images. The 3DCT image set was comprised of 39 images of rotational views of the entire pelvis and the disarticulated fracture hip. Consensus reading by three experts served as a reference standard.

RESULTS

Classification accuracy was 66% using 2DCT, increasing to 73% (p = 0.041) when 3DCT was used. Improvement occurred in the interpretation of transverse and posterior wall-type fractures (p < 0.01 and p = 0.015, respectively), but not in T-type, transverse with posterior wall, or both-column fractures. The improvement was noted only in the graduate trainee group (p = 0.016) but not the radiologist group (p = 0.619). Inter-observer reliability in the graduate trainee group improved from poor to moderate with 3DCT, but remained at a moderate level in both 2DCT and 3DCT in the radiologist group. The overall average interpretation time per case with correct diagnosis was 60 s for 2DCT but only 32 s for 3DCT.

CONCLUSIONS

Standardized 3DCT provides greater reliability and faster diagnosis of acetabular fractures and helps improve the accuracy in transverse- and posterior wall-type fractures. In addition, it helps improve the accuracy of less experienced interpreters.

Learning Acetabular Fracture Classification using a Three-Dimensional Interactive Software: A Randomized Controlled Trial

Acetabular fractures are a real challenge for junior doctors as well as experienced orthopedic surgeons. Correct fracture classification is crucial for appreciating the fracture type, surgical planning, and predicting prognosis. Although three-dimensional (3D) tutorial is believed to improve the understanding of the complex anatomy structure, there have been few applications and randomized controlled trials to confirm it in orthopedics. This study aims to develop a 3D interactive software system for teaching acetabular fracture classification and evaluate its efficacy. Participants were randomly but evenly allocated into either the experimental group (who learned the acetabular fracture classification using a 3D software) or the control group (who used a traditional two-dimensional [2D] tutorial). Both groups were then tasked to classify 10 acetabular fractures and complete a five-point Likert scale on their satisfaction of each learning modality. To calculate significance (P < 0.05), independent t-test was used for normally distributed data whereas Mann-Whitney U test for non-normally distributed data. The experimental group significantly outperformed the control group (t (28) = 2.526, P = 0.017) with identifying correct acetabular fracture classification. Moreover, Likert scale score in the experimental group was also significantly higher than in the control group (Z = 2.477, P = 0.013). This 3D classification software has objectively and subjectively showed an advantage over the traditional 2D tutorial, resulting in an improved classification accuracy and higher Likert scale score. The 3D software has the potential to improve both clinical knowledge as well as identifying correct patient management in orthopedics.

Magnetic Resonance Imaging in Pelvic Fractures – Part 1: Which Criteria Lead Us to Supplementary MRI Diagnostics?

Introduction Isolated pelvic fractures are relatively rare with an incidence of 3 – 6% of all fractures, but their incidence in polytraumatized individuals increases to 25%. The S3 guideline Polytrauma gives a clear recommendation for diagnostics by means of pelvic radiography (X-ray) and computed tomography (CT). A recommendation for the diagnosis by means of magnetic resonance tomography (MRI) especially in patients with low energetic/missing trauma does not currently exist. It is unclear on the basis of which criteria the MRI can be indicated in pelvic fractures. The aim of our study was therefore to retrospectively record indications for the indication of MRI in pelvic fractures – with adequate as well as inadequate trauma.

Material and Methods In a retrospective clinical study, a total of 140 patients (median 68 years, range 15 – 97, 75 female, and 66 male) with a pelvic fracture were included in the study over a period of three years. Overall, the trauma mechanism revealed 73 adequate and 67 inadequate fractures. 31/140 patients had undergone MRI of the pelvis in addition to a CT/X-ray scan. The two subgroups “with MRI” and “without MRI” were analyzed with regard to the parameters “sex”, “age”, “adequacy of the trauma”, “fracture localization”, “duration of admission to imaging”, “type of therapy” and “duration to surgery” compared.

Results It was shown that the MRI diagnosis was performed especially in female, elderly patients (81 years, range 19 – 94 years). Patients with inappropriate trauma have received MRI more frequently (74%) than patients with adequate trauma (26%). With regard to fracture localization no differences could be shown. The MRI was performed on a median 4 days after the CT examination. Regarding the decision “conservative” vs. “operationally” our two groups without and with MRT tended to differ not. Patients with MRI were operated on median 2 days later than patients who did not receive MRI.

Conclusions Pelvic fracture MRI should be performed primarily in elderly female patients without adequate trauma. In patients with adequate trauma, MRI is of low value, especially as MRI diagnostics are performed with delay, resulting in later surgery.

Mapping of both column acetabular fractures with three-dimensional computed tomography and implications on surgical management

Background

The primary goal of this study was to create a frequency map of a series of surgically treated both-column fractures and to explore its implications on surgical management.

Methods

We used a consecutive series of 71 both-column fractures to create 3-dimensional reconstruction images, which were superimposed and oriented to fit a model hemipelvis template by aligning specific pelvis landmarks. Fracture lines were identified and traced to create a fracture map of both-column fractures. Then the possible clinical implications of fracture line map were explored.

Results

Fracture location is closely related to the distribution of fracture line. Of 71 fractures that met the criteria for inclusion, we found the most common pattern demonstrated by coexisting fracture lines. The anterior column was involved by 66% of the fractures extending obliquely from the anterior superior spine to the ischial spine, while 62% of the fractures involved the anterior column extending approximately vertically from the iliac crest to the acetabular roof. Additionally, 39% of the fractures involved the posterior column traversing posterior wall. Furthermore, the high fracture line intensity (n = 65, 92%) formed a Y-shaped pattern, which highlighted the consistency of the patterns.

Conclusions

Surgically treated both-column fractures display very common patterns. The most common pattern is the low anterior column fracture in nearly two thirds of cases, the high anterior column fracture in three fifths of cases and the posterior column fracture with posterior wall involvement in nearly two fifths of cases. These study results may help surgeons to yield insight relevant to surgical approaches, reduction, fixation strategies and even implant design for both-column fractures.

Imaging Acetabular Fractures

Acetabular fractures are encountered by radiologists in a wide spectrum of practice settings. The radiologist's value in the acute and long-term management of acetabular fractures is augmented by familiarity with systematic computed tomography-based algorithms that streamline and simplify Judet-Letournel fracture typing, together with an appreciation of the role of imaging in initial triage, operative decision making, postoperative assessment, prognostication, and evaluation of complications. The steep increase in incidence of acetabular fractures in the elderly over the past several decades places special emphasis on familiarity with geriatric fracture patterns.

3D printing utility for surgical treatment of acetabular fractures

INTRODUCTION

Preoperative 3D modelling enables more effective diagnosis and simulates the surgical procedure.

MATERIAL AND METHODS

We report twenty cases of acetabular fractures with preoperative planning performed by pre-contouring synthesis plates on a 3D printed mould obtained from a computarized tomography (CT) scan. The mould impression was made with the DaVinci 1.0 printer model (XYZ Printing). After obtaining the printed hemipelvis, we proceeded to select the implant size (pelvic Matta system, Stryker^®) that matched the characteristics of the fracture and the approach to be used.

RESULTS

Printing the moulds took a mean of 385minutes (322-539), and 238grams of plastic were used to print the model (180-410). In all cases, anatomic reduction was obtained and intra-operative changes were not required in the initial contouring of the plates. The time needed to perform the full osteosynthesis, once the fracture had been reduced was 16.9minutes (10-24). In one case fixed with two plates, a postoperative CT scan showed partial contact of the implant with the surface of the quadrilateral plate. In the remaining cases, the contact was complete.

CONCLUSIONS

In conclusion, our results suggest that the use of preoperative planning, by printing 3D mirror imaging models of the opposite hemipelvis and pre-contouring plates over the mould, might effectively achieve a predefined surgical objective and reduce the inherent risks in these difficult procedures.

A New, Easy, Fast, and Reliable Method to Correctly Classify Acetabular Fractures According to the Letournel System

Background:

Accurate classification of acetabular fractures remains difficult. To aid in the classification of acetabular fractures and to aid in teaching, our department developed a diagnostic algorithm that involves the use of 1 standardized 3-dimensional reconstruction of a computed tomography (CT) scan (an exopelvic view without the femoral head) with 8 anatomical landmarks. The algorithm was integrated into a smartphone application (app). The main objective of this study was to test the efficacy of this algorithm and smartphone app.

Methods:

Fourteen reviewers (3 experts, 3 fellows, 3 residents, and 5 novice reviewers) evaluated a set of 35 CT scans of acetabular fractures in 2 phases. During the first phase, the scans (including axial 2-dimensional views and 3-dimensional (3D) multiplanar reconstruction views) were assessed by each reviewer twice, with an interval of 4 weeks between the readings to decrease recall bias. During that phase, the reviewers were provided with a diagram of the Letournel classification system with no guidelines for interpretation. During the second phase, performed 4 weeks after the first phase, 1 standardized 3D reconstruction (an exopelvic view without the femoral head) was reviewed twice, with an interval of 4 weeks between the readings. During that phase, the reviewers used the smartphone app. The primary outcome was the accuracy of classification. Interobserver reliability, reading time, and time needed for accurate classification were noted.

Results:

The accuracy of fracture classification was 64.5% when the standard method of analysis was used and 83.4% when the app was used (p < 0.001). Improvement was noted in all groups, with the expert group showing the least improvement (88.6% to 97.2%, p = 0.04) and the novice group showing the most improvement (42.0% to 75.5%, p < 0.001). Furthermore, use of the app greatly increased the accuracy of classification of complex fractures. The average reading time was 71.8 minutes when the standard method was used and 37.4 minutes when the app was used. The interobserver reliability improved in all groups to an excellent reliability (interclass correlation coefficient [ICC] > 0.79).

Conclusions:

The Letournel classification system is difficult to understand and to learn but remains the only system guiding the surgical strategy for acetabular fractures. The impact of diagnostic algorithms is debatable. The most important finding of the present study is the high accuracy for inexperienced groups when the app was used. Another important finding is the high reliability of this method for the diagnosis of complex acetabular fractures.

Postmortem radiological case series of acetabular fractures after fatal aviation accidents

The purpose of this study was to describe radiological fracture patterns of the acetabulum sustained after fatal small aircraft aviation accidents, aiming at facilitating a better understanding of trauma mechanisms in a forensic setting. Postmortem conventional radiographs or CT scans of 29 victims of 20 small aircraft aviation accidents were analyzed for skeletal acetabular trauma. Among the 29 fatalities (27 males and 2 females, median age 55 years (range: 21–76 years)), 20 victims had pelvic fractures (69%), of which 19 victims (66%) had one or more acetabular fractures. Bilateral acetabular fractures occurred in 11 victims. When considering left and right acetabula in each victim as separate entities, 38 of the 58 acetabula included in this case series exhibited one or more fractures. Both the anterior and posterior acetabular columns were fractured in 28 acetabula. Acetabular fractures were frequently encountered in this series of 29 victims of small fatal aircraft accidents. Fractures of the acetabulum occur from ventrally directed impact (i.e. to the knee) or laterally directed impact (i.e. to the greater trochanter of the femur). Radiological descriptions of the fracture patterns can therefore aid in the forensic analysis of the mechanism of trauma in aviation accidents. Postmortem multi-slice CT scan images are preferrable in the assessment of acetabular fractures.

Standardized three dimensional computerised tomography scanner reconstructions increase the accuracy of acetabular fracture classification

PURPOSE

Evaluate the role of four standardized 3D reconstruction views in the accurate diagnosis of acetabular fractures.

MATERIALS AND METHODS

Thirty-five acetabular fracture cases were selected from a tertiary centre database. Fourteen reviewers with different experience level evaluated this set of images which were provided in axial 2D views and multiplanar reconstruction (MPR) without 3D views in the first two readings then the standardized 3D views were added for the subsequent two readings. The primary outcome was the accuracy of diagnosis while inter-observer reliability and reading time as well as time needed for accurate diagnosis were evaluated.

RESULTS

Accuracy of classification was 56.7% using the 2D and 73% using the described 3D (p < 0.001). Improvement was noted in all groups even though the expert group showed the least improvement (6.7% (p = 0.04)) and the least experience group showed the most improvement (35.7% (p < 0.001)). Average time of interpretation was 96 minutes for the 2D sets and 47 minutes for the 3D sets. Finally, the adding of the four standardized views increased the inter-observer reliability in all groups compared to the standard 2D sets with MPR.

CONCLUSION

Acetabular fracture diagnosis according to Letournel classification is difficult and depends greatly on the experience of the reader. The described set of 3D images yields better accuracy and renders the diagnosis more repeatable and faster. We recommend the use of these images in classifying acetabular fractures.

Three-dimensional printing model improves morphological understanding in acetabular fracture learning: A multicenter, randomized, controlled study

Conventional education results in unsatisfactory morphological understanding of acetabular fractures due to lack of three-dimensional (3D) details and tactile feedback of real fractures. Virtual reality (VR) and 3D printing (3DP) techniques are widely applied in teaching. The purpose of this study was to identify the effect of physical model (PM), VR and 3DP models in education of morphological understanding of acetabular fractures. 141 students were invited to participate in this study. Participants were equally and randomly assigned to the PM, VR and 3DP learning groups. Three-level objective tests were conducted to evaluate learning, including identifying anatomical landmarks, describing fracture lines, identifying classification, and inferring fracture mechanism. Four subjective questions were asked to evaluate the usability and value of instructional materials. Generally, the 3DP group showed a clear advantage over the PM and VR groups in objective tests, while there was no significant difference between the PM and VR groups. 3DP was considered to be the most valuable learning tool for understanding acetabular fractures. The findings demonstrate that 3DP modelling of real fractures is an effective learning instrument that can be used to understand the morphology of acetabular fractures and promote subjective interest.

Creating Three-dimensional Printed Models of Acetabular Fractures for Use as Educational Tools

Acetabular fractures are frequently encountered in some clinical practices, and the precise classification of these fractures greatly influences treatments and outcomes. The authors identified the need for an educational aid when teaching acetabular fracture classifications, given the complex spatial anatomy and the nonintuitive classification system that is commonly used. Three-dimensional ( 3D three-dimensional ) printing is an evolving technique that has applications as an educational aid, providing the student with a tangible object to interact with and learn from. In this article, the authors review their experience creating 3D three-dimensional printed models of the hip for educational purposes. Their goal was to create 3D three-dimensional printed models for use as educational aids when teaching acetabular fracture classifications. Complex cases involving a combination of fracture types, subtle nondisplaced fractures, and/or fractures with associated osteopenia or artifacts were excluded. The selected computed tomographic (CT) scans were loaded into a medical 3D three-dimensional volume-rendering program, and a 3D three-dimensional volumetric model was created. Standard Tessellation Language ( STL Standard Tessellation Language ) files were then exported to STL Standard Tessellation Language model-editing software and edited to retain only the involved hemipelvis. In some cases, the proximal femur and ipsilateral hemisacrum may be included to emphasize hip alignment or disruption of the force transfer. Displaced fracture fragments can be printed as separate segments or a single unit after the addition of struts. Printing was performed by using an additive manufacturing principle, with approximately 36-48 hours needed for printing, postprocessing, and drying. The cost to print a 1:1 scale model was approximately $100-$200, depending on the amount of plastic material used. These models can then be painted according to the two-column theory regarding acetabular fractures. ^©RSNA, 2017.

The design, production and clinical application of 3D patient-specific implants with drilling guides for acetabular surgery

An innovative procedure for the development of 3D patient-specific implants with drilling guides for acetabular fracture surgery is presented. By using CT data and 3D surgical planning software, a virtual model of the fractured pelvis was created. During this process the fracture was virtually reduced. Based on the reduced fracture model, patient-specific titanium plates including polyamide drilling guides were designed, 3D printed and milled for intra-operative use. One of the advantages of this procedure is that the personalised plates could be tailored to both the shape of the pelvis and the type of fracture. The optimal screw directions and sizes were predetermined in the 3D model. The virtual plan was translated towards the surgical procedure by using the surgical guides and patient-specific osteosynthesis. Besides the description of the newly developed multi-disciplinary workflow, a clinical case example is presented to demonstrate that this technique is feasible and promising for the operative treatment of complex acetabular fractures.

Magnetic Resonance Imaging of Nonneoplastic Musculoskeletal Pathologies in the Pelvis

Musculoskeletal pathologies in the pelvis encompass a wide variety of lesions including femoroacetabular impingement, athletic pubalgia, ischiofemoral impingement, and apophyseal avulsion injuries. Magnetic resonance imaging is the noninvasive imaging modality of choice for the diagnosis and management of these lesions. In this article, the authors discuss the nonneoplastic musculoskeletal lesions in the pelvis, with illustrations and relevant case examples.

Practicality of exchanging transparent 3D CT for radiography for pelvic fractures

OBJECTIVE

We assess the utility of transparent 3D reconstructed CT images for evaluation of traumatic pelvic bony injuries compared to traditional radiographs.

METHODS

Radiographs and 3D reconstructed CT were anonymized and randomized before review by 4 board certified physicians using a standardized questionnaire and compared to a gold-standard axial CT by a fifth board certified physician.

RESULTS

49 patients were included. We found significant agreement (K=[0.5-0.92], p<0.001) and comparable accuracy (K=[0.36-0.38], p<0.02) and ghost images of radiographs and transparent 3D reconstructed CT without a difference in confidence (p=0.38).

CONCLUSION

Transparent 3D reconstructed CT images may be sufficient for pelvic trauma injury without the use of radiographs.

Improved acetabular fracture diagnosis after training in a CT-based method

BACKGROUND

Acetabular fractures remain challenging to diagnose, particularly when they are complex. An accurate diagnosis is nevertheless crucial to select the best surgical strategy. None of the training methods described to date relies on the Letournel classification with a detailed analysis of each abnormality seen by computed tomography (CT). We therefore prospectively assessed a CT-based diagnostic method by (1) determining the rate of correct diagnoses by orthopaedic surgeons before and after training in the method, (2) comparing the times needed to read the CT images before and after training, (3) and assessing the repeatability of the method.

HYPOTHESIS

Training in the CT-based diagnostic method significantly increases the rate of correct diagnoses.

METHOD

The CT-based diagnostic method involves analysing eight anatomical landmarks in the anterior, posterior, and no man's land zones. From our institutional database (450 cases between 2007 and 2016), we selected 35 acetabular fractures that replicated the overall distribution of fracture types. The images were reviewed by 10 inexperienced and 3 experienced readers before and after they received training in the CT-based diagnostic method. The rates of correct diagnoses and times needed to read the images were compared. Finally, an additional reading was performed to allow an assessment of reproducibility.

RESULTS

After training, the rate of correct diagnoses by the unexperienced readers improved by 16.64% for all fractures combined (from 212/350, 60.5% [37-83%] to 270/350, 77.14% [63-86%]; P=0.001) and by 25.9% for associated fractures (from 90/180, 50% [11-89%] to 114/140, 75.6% [61-90%]; P=0.003). Mean time required by the inexperienced readers to interpret the 35 sets of images decreased after training, from 66.1 to 47.6min (i.e., a 1.22-minute decrease per patient, P=0.001). None of the study variables changed significantly after training of the experienced readers (P>0.05). Reproducibility among the inexperienced readers was 0.78.

CONCLUSION

Analysing the eight anatomical landmarks located in the anterior, posterior, and no man's land zones is a simple and reproducible method for diagnosing all fracture patterns defined by the Letournel classification.

LEVEL OF EVIDENCE

Level III, non-randomised prospective case-control diagnostic study.

[Management of complex acetabulum fractures and their consequences]

In the structure of pelvic bone injuries, acetabular fractures are the most complex type and, according to different authors, account for up to 20% [1]. The severity of these injuries is confirmed by the fact that early descriptions of acetabular fracture were based only on the results of autopsies of patients who had suffered a combined injury. Thus, as early as 1788, Callisen reported an acetabular fracture, but without a detailed description of the nature of the injury. In 1909, Schroeder provided a detailed report of 49 cases of acetabular fractures reported in the literature. Most of them were described during autopsies of patients who died from complications associated with hemorrhagic shock or the onset of sepsis [2]. Fractures of the acetabulum in most observations are the result of high-energy impacts, usually as a result of traffic accidents; therefore, the mechanism of injury determines the combined and multiple nature of the injuries in the victims. A significant proportion of acetabular fractures (up to 60%) are accompanied by fragment displacement and dislocation of the femoral head, in which the most severe tissue changes occur [3].

Early reduction of acetabular fractures decreases the risk of post-traumatic hip osteoarthritis?

BACKGROUND

Acetabular fractures are complex high-energy injuries. Increasing in recent years with the increased use of high-speed motor vehicles. One of the most important complications of acetabular fracture is the post-traumatic hip osteoarthritis; this complication has been associated to poor fracture reduction, type of fracture and delay in the reduction and fixation of acetabular fracture (Timing surgery). The aims of this study were to determine the incidence of post-traumatic hip osteoarthritis after acetabulum fracture and demonstrate whether the delay surgery is associated to early post-traumatic hip osteoarthritis.

METHODS

Using the database of patients with acetabular fractures treated with open reduction and internal fixation (ORIF) over 3 years (2011-2014) with minimum of 2 years follow-up. Data was acquired and saved in a digital format. Demographic information was obtained from each patient with minimum of 2 years follow-up. Acetabular fracture was distributed according to the classification of Judet. The quality of reduction was classified in anatomic (0-1 mm) and non-anatomic (>1 mm) and the timing surgery, early (<7 days) and delay (>7 days). Clinical and radiographic follow-up was generally performed at six weeks, three months, one and two years after fracture fixation. Multivariate logistic regression analyses were performed to assess the strength of the covariates in relation to the development of post-traumatic hip osteoarthritis.

RESULTS

59 (48%) patients of 122, developed post-traumatic hip osteoarthritis before 2 years. Posterior wall fracture with or without transverse fracture was associated with higher post-traumatic hip osteoarthritis compared with other types of fractures (p < 0.05). Patients with better anatomical reduction had less post-traumatic hip osteoarthritis compared with those who had nonanatomic reduction (p < 0.05). There was no evidence of association between early timing of the surgical procedure and the presence post-traumatic hip osteoarthritis (p = 7092).

CONCLUSIONS

According to our results, the anatomical reduction of the articular surface in acetabular fractures is the most important factor in hip osteoarthritis prevention. This factor is strongly associated with early surgical treatment, preferably done within seven days. The timing surgery it is not a factor associated with post-traumatic osteoarthritis.

A combination of three-dimensional printing and computer-assisted virtual surgical procedure for preoperative planning of acetabular fracture reduction

OBJECTIVE

Treatment of acetabular fractures remains one of the most challenging tasks that orthopaedic surgeons face. An accurate assessment of the injuries and preoperative planning are essential for an excellent reduction. The purpose of this study was to evaluate the feasibility, accuracy and effectiveness of performing 3D printing technology and computer-assisted virtual surgical procedures for preoperative planning in acetabular fractures. We hypothesised that more accurate preoperative planning using 3D printing models will reduce the operation time and significantly improve the outcome of acetabular fracture repair.

METHODS

Ten patients with acetabular fractures were recruited prospectively and examined by CT scanning. A 3-D model of each acetabular fracture was reconstructed with MIMICS14.0 software from the DICOM file of the CT data. Bone fragments were moved and rotated to simulate fracture reduction and restore the pelvic integrity with virtual fixation. The computer-assisted 3D image of the reduced acetabula was printed for surgery simulation and plate pre-bending. The postoperative CT scan was performed to compare the consistency of the preoperative planning with the surgical implants by 3D-superimposition in MIMICS14.0, and evaluated by Matta's method.

RESULTS

Computer-based pre-operations were precisely mimicked and consistent with the actual operations in all cases. The pre-bent fixation plates had an anatomical shape specifically fit to the individual pelvis without further bending or adjustment at the time of surgery and fracture reductions were significantly improved. Seven out of 10 patients had a displacement of fracture reduction of less than 1mm; 3 cases had a displacement of fracture reduction between 1 and 2mm.

CONCLUSIONS

The 3D printing technology combined with virtual surgery for acetabular fractures is feasible, accurate, and effective leading to improved patient-specific preoperative planning and outcome of real surgery. The results provide useful technical tips in planning pelvic surgeries.

Core curriculum illustration: posterior column acetabular fracture

This is the 17th installment of a series that will highlight one case per publication issue from the bank of cases available online as part of the American Society of Emergency Radiology (ASER) educational resources. Our goal is to generate more interest in and use of our online materials. To view more cases online, please visit the ASER Core Curriculum and Recommendations for study online at: http://www.aseronline.org/curriculum/toc.htm.