Differences of percutaneous retrograde screw fixation of anterior column acetabular fractures between male and female: a study of 164 virtual three-dimensional models

Determinants for successful medullary fixation of the superior ramus

OBJECTIVES

The purpose of this study is to determine what demographic and anatomical variables affect successful placement of a superior medullary ramus screw, and how they affect the maximal diameter of that screw.

METHODS

Design: Prognostic Level IV SETTING: Level I Trauma Center Patients/Participants: Two hundred consecutive patients underwent computed tomography (CT) of the pelvis. We included those patients aged 18 and older without osseous injury or abnormalities precluding measurement.

INTERVENTION

3D reconstructions of the pelvis were created, and a virtual 3.5 mm cylindrical implant was placed from the pubic tubercle to the lateral cortex of the ilium. Success was defined as a bicortical virtual screw path from the ramus to the lateral ilium without cortical perforation. The cylinder was then expanded to model varying screw diameters. We then repeated this same process for unicortical retrograde screw insertion ending medial to the acetabular joint.

MAIN OUTCOME MEASURES

Successful screw placement and maximum screw diameter.

RESULTS

A 3.5 mm screw was successfully placed in 187 patients (93.5 %). One male (1/107, 0.9 %) and 12 females (12/93, 12.9 %) could not accommodate a 3.5 mm screw. All cases of perforation occurred lateral to the obturator foramen. Increasing height was associated with success, and male gender was associated with the ability to accommodate screws with a diameter 6.5 mm and larger.

CONCLUSIONS

Most patients can accommodate a 3.5 mm screw from the pubic tubercle to the ilium. Height and gender should be noted when planning medullary ramus fixation.

Special screw corridors and imaging in pelvic ring trauma

Adequate intraoperative visualization is mandatory for implant application in pelvic ring injuries. Several fluoroscopic X-ray views are in practical use. The gold standard primary X-ray is the anteroposterior view of the pelvis. In addition to this view, oblique views for pelvic ring instabilities and acetabular fractures are well defined. Combinations of these views allow better identification of osseous corridors for screw applications. These corridors are based on the 3-ring concept of the hemipelvis. For pelvic ring stabilization the main osseous corridors include the retrograde and antegrade superior ramus/anterior column corridor, the supraacetabular corridor and the gluteus medius pillar corridor. The radiographic anatomy of these corridors is described in detail for screw applications with definition of image intensifier angulations, risk zones and corridor parameters. This allows for intraoperative safe implant application.

Chronic pelvic insufficiency fractures and their treatment

Fragility and insufficiency fractures of the pelvis (FFP) and sacrum (SIF) are increasingly prevalent, particularly among the elderly, due to weakened bone structure and low-energy trauma. Chronic instability from these fractures causes persistent pain, limited mobility, and significant reductions in quality of life. Hospitalization is often required, with substantial risks of loss of independence (64-89%) and high mortality rates (13-27%). While conservative treatment is possible, surgical intervention is preferred for unstable or progressive fractures. FFP and SIF are primarily associated with osteoporosis, with 71% of patients not receiving adequate secondary fracture prevention. Imaging modalities play a crucial role in diagnosis. Conventional radiography often misses sacral fractures, while computed tomography (CT) is the gold standard for evaluating fracture morphology. Magnetic resonance imaging (MRI) offers the highest sensitivity (99%), essential for detecting complex fractures and assessing bone edema. Advanced techniques like dual-energy CT and SPECT/CT provide further diagnostic value. Rommens and Hofmann's classification system categorizes FFP based on anterior and posterior pelvic ring involvement, guiding treatment strategies. Progression from stable fractures (FFP I-II) to highly unstable patterns (FFP IV) is common and influenced by factors like pelvic morphology, bone density, and sarcopenia. Treatment varies based on fracture type and stability. Non-displaced posterior fractures can be managed with sacroplasty or screw fixation, while displaced or unstable patterns often require more invasive methods, such as triangular lumbopelvic fixation or transsacral bar osteosynthesis. Sacroplasty provides significant pain relief but has limited stabilizing capacity, while screw augmentation with polymethylmethacrylate improves fixation in osteoporotic bones. Anterior ring fractures may be treated with retrograde transpubic screws or symphyseal plating, with biomechanical stability and long-term outcomes depending on fixation techniques. FFP and SIF management requires a multidisciplinary approach to ensure stability, pain relief, and functional recovery, emphasizing early diagnosis, tailored surgical strategies, and secondary prevention of osteoporotic fractures.

Dependable Automated Approach for Measuring the Retrograde Superior Ramus Screw Corridor in Pelvic Fracture Fixation

BACKGROUND

Precise measurement of the intraosseous corridor within the superior pubic ramus is essential for the accurate percutaneous placement of a retrograde superior ramus screw (SRS). However, conventional manual measurement methods are often subjective, leading to variations in results among observers. Our goal was to develop an automated and dependable method for determining the retrograde SRS corridor.

METHODS

We developed an automated technique that utilized a computed tomography (CT) image-based search algorithm to identify the retrograde SRS corridor with the maximum diameter. We evaluated the reliability of this automated approach in comparison to a manual method using 17 pelves. Subsequently, we used both methods to measure the diameter, length, and orientation of the retrograde SRS corridor in 204 pelves in a Chinese population and assessed the intra- and interobserver agreement of each method by calculating the root-mean-square error (RMSE) and constructing Bland-Altman plots. We determined the screw applicability (percentages of hemipelves that could be treated with specific sizes of screws) for each method. Additionally, we investigated potential factors influencing the corridor, such as sex, age, height, and weight, through regression analysis.

RESULTS

The intra- and interobserver intraclass correlation coefficients (ICCs) for the automated method (0.998 and 0.995) were higher than those for the manual approach (0.925 and 0.918) in the assessment of the corridor diameter. Furthermore, the diameter identified by the automated method was notably larger than the diameter measured with the manual method, with a mean difference and RMSE of 0.9 mm and 1.1 mm, respectively. The automated method revealed a significantly smaller corridor diameter in females than in males (an average of 7.5 and 10.4 mm, respectively). Moreover, use of the automated method allowed 80.6% of the females to be managed with a 4.5-mm screw while a 6.5-mm screw could be utilized in 19.4%, surpassing the capabilities of the manual method. Female sex had the most substantial impact on corridor diameter (β = -0.583).

CONCLUSIONS

The automated method exhibited better reliability than the manual method in measuring the retrograde SRS corridor, and showed a larger corridor diameter for screw placement. Females had a significantly smaller corridor diameter than males. Given the intricate nature of the automated approach, which entails utilizing different software and interactive procedures, our current method is not readily applicable for traumatologists. We are working on developing integrated software with the goal of providing a more user-friendly solution for traumatologists in the near future.

LEVEL OF EVIDENCE

Diagnostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Clinical results of acetabular fracture treatment with hybrid fixation by anterior and posterior approach : A minimally invasive technique

BACKGROUND

Open reduction and internal fixation have been described as the gold standard for the treatment of acetabular fractures, but the high complications of these surgeries have led surgeons to seek less invasive procedures. In recent years, minimally invasive treatment, such as fixation through the skin have been proposed. The aim was to assess acetabular fracture outcomes of combination of posterior approach (Kocher-Langenbeck [KL]) with anterior percutaneous screw fixation (APSF) with minimally invasive surgery (MIS).

METHODS

Between February 2017 and July 2019, 155 patients with acetabular fractures underwent fixation with the KL + APSF approach. For 1 year functional outcomes, radiographic findings, and postoperative complications were evaluated.

RESULTS

Of 155 patients with a mean age of 40.16 ± 10.32 years, 82 patients were male and 73 were female. The most common pattern of fracture was both columns (32.9%). The average blood loss was approximately 527 ml. The average operation time was 85 min. The mean length of surgical incision was 113.3 mm. Harris' hip score was excellent in 75.5% of cases. The mean VAS score was approximately 4 and 91.6% of patients returned to pre-trauma activity. In 74.8% of cases, the reduction was anatomical. Complications after surgery were very insignificant and included the following: 2 patients had foot drop within 5 months both patients recovered, 2 patients had femoral nerve palsy and 3 cases of deep vein thrombosis and 1 case of pulmonary thromboembolism were treated. There were four patients with surgical site infections, all of whom recovered and two of the seven patients with osteoarthritis underwent total hip arthroplasty.

CONCLUSION

Combining posterior approach with minimally invasive anterior method in fixation and treatment of acetabular fractures is a safe and reliable method and showed significant functional results with minimal complications.

Acetabular posterior column screws via an anterior approach

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

Description of Standardized Planes and Angles for Percutaneous Supra-acetabular Screw Placement

BACKGROUND

Percutaneous screw fixation for pelvic fractures has become a minimally invasive alternative to an open operation. The complex anatomy of the pelvis renders this procedure challenging. The objective of this study was to assess standardized angles and dimensions of safety zones within a 3 D computed tomography model for optimal supra-acetabular screw placement.

METHODS

Computed tomography scans of 107 patients that suffered major trauma without showing any bone injury of the pelvis were collected. Using a software-based analysis, raw computed tomography data were transformed into 3 D models to set standardized landmarks and determine the possible insertion corridor.

RESULTS

Screws not exceeding a length of 97 mm in females and 106.4 mm in males were, in 95% of the evaluated cases, insertable without cortical bone penetration. The safety zone was 6.6 mm for females and 7.9 mm for males. Screws not exceeding these diameters were safely insertable in 95% of the cases. For the midsagittal plane, the angle was 36.4 ± 5.1 on the left and 34.7 ± 2.9 on the right (p = 0.008). For the anterior pelvic plane, the angle was 31.3 ± 4.5° on the left and 34.0 ± 4.8° on the right (p = 0.008).

CONCLUSIONS

Percutaneous fixation using supra-acetabular screws is a promising method to treat simple supra-acetabular fractures. These results may improve its safe utilization and could facilitate its broader clinical application.

Posterior Wall Fragments in Acetabular Both-Column Fractures: Morphology, Type, and the Significance of its Projection

OBJECTIVE

Most both-column acetabular fractures are combined with posterior wall fragments. However, the morphology of this posterior wall is varied, and how to fix this posterior wall remains a controversial topic. To investigate the morphological characteristics of posterior wall fragments of both-column acetabular fractures and select corresponding fixation methods.

METHODS

Data from 352 patients with acetabular fractures admitted to the level one trauma centre in our hospital between January 2006 and December 2022 were collected. The morphology of posterior wall fragments was observed and analyzed in 83 cases of both-column acetabular fractures and classified according to the consistency of posterior wall morphology. A fracture map of the posterior wall was created on a normal template according to the three morphological types of posterior wall fragments. Finally, the high-incidence area of the posterior wall fracture was projected onto the iliac fossa and the medial side of the posterior column to guide the fixation of the posterior wall fragment using the anterior intrapelvic approach.

RESULTS

Fractures were divided into four types: I, large posterior wall fragment which was high in the ilium bone (34 cases, 41.0%); II, posterior wall fragment in the acetabular parietal region (18 cases, 21.7%); III, posterior wall marginal fracture (10 cases, 12.0%); and IV, non-combined posterior wall fracture (21 cases, 25.3%). The most common morphologies of the posterior wall fragments of the first two types were mapped and projected onto the anterior iliac inner plate and medial side of the posterior column, where the corresponding area could be used to guide the insertion of the internal fixation.

CONCLUSION

Both-column acetabular fractures combined with posterior wall fractures can be divided into four types according to the morphology of the posterior wall fragment. Understanding the corresponding three-dimensional morphology and projection position of different types of these fragments can help surgeons determine the position and orientation of internal fixation of posterior wall fractures.

Evaluation of the superior pubic ramus and supra acetabular corridors using statistical shape modelling

INTRODUCTION

The incidence of osteoporotic pelvic fractures is increasing. The broken anterior pelvic ring is preferentially fixed with long intramedullary screws, which require a good understanding of the patient-specific anatomy to prevent joint perforation. The aim of this study was to assess the variability of the superior pubic ramus and the supra acetabular corridors' length and width using statistical shape modelling.

MATERIALS AND METHODS

A male and female statistical shape model was made based on 59 forensic CT scans. For the superior pubic ramus and the supra acetabular corridor the longest and widest completely fitting cylinder was created for the first 5 principal components (PC) of both models, male and female pelvises separately.

RESULTS

A total of 59 pelvises were included in this study of which 36 male and 23 female. The first 5 principal components explained 75% and 79% of the pelvic variation in males and females, respectively. Within 3 PCs of the female statistical shape model (SSM) a superior pubic ramus corridor of < 7.3 mm was found, 5.5 mm being the narrowest linear corridor measured. Both corridors in all PCs of the male SSM measured > 7.3 mm.

CONCLUSION

Within females a 7.3 mm and 6.5 mm screw won't always fit in the superior pubic ramus corridor, especially if a flat sacrum, a small pelvis or a wide subpubic angle are present. The supra acetabular corridor did not seem to have sex-specific differences. In the supra-acetabular corridor there was always enough space to accommodate a 7.3 mm screw, both in males and females.

Antegrade anterior column acetabulum fracture fixation with cannulated compression headless screws-A biomechanical study on standardized osteoporotic artificial bone

PURPOSE

Due to the increase in life expectancy and high-energy traumas, anterior column acetabular fractures (ACFs) are also increasing. While open reduction and internal fixation (ORIF) is still the standard surgical procedure, minimally invasive, percutaneous fixation of osteoporotic acetabulum fractures (AF) are growing in popularity. The aim of this biomechanical study was to evaluate the biomechanical competence following antegrade fixation with a standard screw versus a cannulated compression headless screw.

METHODS

Eight anatomical osteoporotic composite pelvises were given an anterior column fracture. Two groups of eight specimens each (n = 8) for fixation with either a 6.5 mm cannulated compression headless screw in group Anterior Acetabulum Canulated Compression Headless Screw (AACCH), or with a 6.5 mm partially threaded cannulated screw in group Anterior Acetabulum Standard Screw (AASS) where compared. Each specimen was biomechanically loaded cyclically at a rate of 2 Hz with monotonically increasing compressive load until failure. Motions were assessed by means of optical motion tracking.

RESULTS

Initial construct stiffness trended higher in group AACCH at 152.4 ± 23.1 N/mm compared to group AASS at 118.5 ± 34.3 N/mm, p = 0.051. Numbers of cycles and corresponding peak load at failure, were significantly higher in group AACCH at 6734 ± 1669 cycles and 873.4 ± 166.9 N versus group AASS at 4440 ± 2063 cycles and 644.0 ± 206.3 N, p = 0.041. Failure modes were breakout of the screws around the proximal entry point.

CONCLUSION

From a biomechanical perspective, group AACCH was associated with superior biomechanical competence compared to standard partially threaded cannulated screws and could therefore be considered as valid alternative for fixation of anterior acetabulum fractures.

A standard canulated screw may not fit up to 1/3 of the patients treated percutaneously for anterior column acetabular fractures-A pilot study

A proper evaluation of the narrowings and length of the anterior acetabular column would offer better predictability and precision for implant insertion in the case of an acetabular fracture.

OBJECTIVE

To determine the diameter and length of the safety corridor of the anterior column of the acetabulum in patients with available pelvic computed tomography (CT), analyze the obtained measurements against those of a standard 6.5-mm implant, and verify possible sex differences regarding these measurements. A secondary aim was to develop a method for measurement of the anterior column of the acetabulum based on CT images.

MATERIALS AND METHODS

In 200 CT scans of hemipelvises we measured the diameter of two areas of narrowing and the length of the safety corridor of the anterior column. The images were submitted to multiplanar reformatting adjusted to a plane orthogonal to the bone corridor, drawn at the level of the superior pubic ramus.

RESULTS

Measurement #1 had a mean value of 8.12 (2.27) mm in the overall sample and median values of 9.03 (7.76-10.48) mm in men and 6.77 (5.44-7.19) mm in women. Measurement #2 had a mean value of 7.29 (2.19) mm and median values of 8.23 (7.18-9.82) mm in men and 5.9 (4.65-7.19) mm in women. Measurement #3 had a mean value of 109.53 (13.66) mm in the overall sample and median values of 117.17 (112.9-122.9) mm in men and 100.91 (90.95-111.17) mm in women (p<0.001 all three measurements). Measurement #1 was smaller than 6.5 mm in 22.5% of the patients (of whom 90% were women). Measurement #2 was smaller than 6.5 mm in 35% of the patients (of whom 80% were women).

CONCLUSIONS

This study proposed an anatomic evaluation of the anterior column of the acetabulum using conventional CT images The areas of narrowing in the anterior column had an average of 8.12 mm at the level of the pubic tubercle and 7.29 mm at the level of the acetabular fossa. The mean length of the safety corridor was 109.53 mm. In 35% of the cases, a 6.5 mm percutaneous screw would have violated the cortical bone of the safety corridor.

Evaluation of the effect of pelvis type in percutaneous acetabular column fixation: a computed tomography study

This study aimed to evaluate the effect of pelvis type in percutaneous acetabular column fixation. What is the effect of pelvis type in percutaneous acetabular colon fixation? The available pelvic computed tomography (CT) scans which were obtained in the diagnostic imaging center with a 1 mm slice width were evaluated. The pelvic type was classified with the help of MPR (Multiplanar Reformat) and 3D (Three Dimensional) imaging modes. All evaluated bony pelvic structures were anatomically intact. 40 types of android, gynecoid, anthropoid, and platypelloid pelvis were determined. CT sections were created in MPR imaging mode. Anterior obturator oblique (AOO) and inlet images were created for anterior column evaluation, while iliac oblique (IO) and outlet images were created for posterior column evaluation. The possibility of obtaining a linear corridor for acetabular columns was investigated by measuring corridor width and lengthon images of pelvic CTs. A linear corridor could not be obtained between the pubic tubercle and the supraacetabular region of 12 (30%) CTs in the anterior column of gynecoid pelvis group. The diameter of the anterior column corridor was below 5.5 mm in 10 (25%) of Gynecoid pelvis group, 5 (12.5%) of Anthropoid pelvis group, and 10 of Platypelloid pelvis group, , and all those scans belonged to the female gender. There was a statistically significant difference between pelvis types in terms of anterior and posterior column diameters (p <0.001). While the android pelvis type had the highest diameter and corridor length in both anterior column and posterior column measurements, the gynecoid pelvic type had the lowest diameter and corridor length. In the evaluations made according to gender, both anterior and posterior column diameters were larger and longer in males than in females (p <0.001). Pelvis type is an important factor which can affect anterior and posterior column diameter and length of acetabulum. Pelvic typing before acetabular surgery can help the surgeon determining the most appropriate patient position, surgical approach, and implant selection. Level of Evidence: Level 2.

Iliac dysmorphism: defining radiographic characteristics and association with pelvic osseous corridor size

INTRODUCTION

Insertion of iliac wing implants requires understanding of the curvilinear shape of the ilium. This study serves to quantitatively identify the area of iliac inner-outer table convergence (IOTC), characterize the iliac wing osseous corridor, and define the gluteal pillar osseous corridor.

METHODS

Computed tomography scans of 100 male and 100 female hemipelves were evaluated. The iliac wing was studied using manual best-fit analysis of the bounds of the inner and outer cortices. The IOTC was defined as the location of the iliac wing with an intercortical width less than 5 mm. The shortest distance from the apex of the iliac crest to the superior border of the IOTC was defined as the iliac wing osseous corridor. Finally, the width of the gluteal pillar corridor from the gluteus medius tubercle to the ischial tuberosity was measured.

RESULTS

The IOTC is an elliptical area measuring 22.3 cm². All ilia had an area where the inner and outer cortices converged to an intercortical width of less than 5 mm; 48% converged to a single cortex. The shortest mean distance from the superior edge of the iliac crest to the beginning of the IOTC was 20.3 mm in men and 13.8 mm in women (p < 0.001). The gluteal pillar diameter averaged 5.3 mm in men and 4.3 mm in women (p < 0.001).

DISCUSSION

All ilia converge to a thin and frequently unicortical central region. A 4.5 mm iliac wing lag screw will not breach the cortex if it remains within 20 mm or 14 mm distal to the cranial aspect of the iliac crest in males and females, respectively. Not only is the gluteal pillar smaller than previously thought, in 41% of males and 73% of females, it is not be large enough for 5 mm implants.

CONCLUSION

This study quantitatively assesses the dimensions of the IOTC, the iliac crest osseous corridor, and the gluteal pillar. Overall, our findings provide improved understanding of the limits for implant use in the iliac wing as well as better appreciation of the complex osteology of the ilium. This will help surgeons to identify safe areas for implant placement and avoid inadvertent cortical penetration.

A computed tomography (CT) based morphometric study of superior pubic ramus anatomy among Arabs to determine safe intramedullary pubic rami screw insertion

PURPOSE

To assess the morphometric variables of the superior pubic ramus in an Arab/ Middle Eastern population to establish a safe pubic screw fixation technique.

METHODS

Cross-sectional retrospective analysis of computed tomography (CT) pelvic images. Morphometric data were extracted including; on pubic ramus length, insertion angles, potential danger zones and ramus diameters. The correlation between pubic rami diameter and patient demographics was also analyzed.

RESULTS

A total of 231 participants were included (45% female). The mean pubic ramus length was 104 mm in females and 127 mm in males. The narrowest canal diameters at the para-symphyseal area were; 7.35 mm (males) and 4.75 mm (females). The mediolateral insertion angle was 49.4° in females and 41.8° in males. The cephalic-caudal angle was 49.9° in males and 42.1° in females. The mean distance from the lateral ilium entry point to the joint articular surface was 23.5 mm in males and 19.9 mm in females. The symphysis pubis to tubercle exit point was higher in females than males (24.2 mm vs 16.6 mm, respectively). There was a significant positive correlation between age and pubic ramus diameters in all age groups.

CONCLUSION

The results from this study suggest that percutaneous pubic rami screw fixation using the standard 6.5 or 7.3 mm cannulated screw system may potentially be unsafe in female Arab patients. This subset of patients may require alternative non-cannulated screws (3.5-4.5 mm) or plate options. Further, female patients may have a higher risk of acetabular joint penetration, while males have a potentially higher risk of pudendal nerve injury.

A 13-Year Study of Fatal Falls From Height in Northern Tunisia

INTRODUCTION

Falls from height are a major cause of unintentional injury death, resulting in high disability and mortality. We investigated the characteristics of fatal falls and their relationship with intentionality, injury patterns, and death on impact.

MATERIALS AND METHODS

In this retrospective study, we examined 545 cases of fatal falls from height that underwent autopsy in the forensic department of the Charles Nicolle hospital of Tunis (Tunisia) between January 2008 and December 2020. Cases were reviewed in terms of demographics, fall characteristics, and autopsy findings.

RESULTS

The population was predominately male (86.6%). Four hundred twenty-one (77.3%) originated from accidents, 120 (22%) were found to be suicidal, with 4 homicide cases. A notable decline in cases was noticed following the Jasmine revolution, 2011 (R squared = 0.8). The mean height of falls was 8 m. Higher falls were associated with a set of organ-specific injuries. Organ injury pattern did not differ based on intentionality. Female victims were 2.4 times more likely to sustain pelvic injuries than males. The majority of victims deceased before reaching health care structures. Death on impact was strongly associated with higher falls, cranial impact, and organ-specific injuries, including cardiac, pulmonary, and skull injuries.Falls from height are in many cases preventable. A clearly defined fall safety policy, strict implementation of evidence-based interventions, efficient allocation of resources, and raising safety awareness must to be urgently implemented.

CONCLUSION

Understanding patterns of injury and the factors that influence death on impact may be of further interest in the prevention and management of survivors in the acute period.

Entry Point Variation in the Osseous Fixation Pathway of the Anterior Column of the Pelvis—A Three-Dimensional Analysis

Fractures of the superior pubic ramus can be treated with screw insertion into the osseous fixation pathway (OFP) of the anterior column (AC). The entry point determines whether the screw exits the OFP prematurely. This can be harmful when it enters the hip joint or damages soft tissues inside the lesser pelvis. The exact entry point varies between patients and can be difficult to ascertain on fluoroscopy during surgery. The aim of this study was to determine variation in the location of the entry point. A retrospective single center study was performed at a level 1 trauma center in the Netherlands. Nineteen adult patients were included with an undisplaced fracture of the superior pubic ramus on computer tomography (CT)-scan. Virtual three-dimensional (3D) models of the pelvises were created. Multiple screws were placed per AC and the models were superimposed. A total of 157 screws were placed, of which 109 did not exit the OFP prematurely. A universally reproducible entry point could not be identified. A typical crescent shaped region of entry points did exist and was located more laterally in females when compared to males. Three-dimensional virtual surgery planning can be helpful to identify the ideal entry points in each case.

Navigation Template Design and the Anatomic Measurement for Anterograde Transpubic Screws

OBJECTIVE

For pelvic ring fractures, screw fixation became a popular technique for its good biomechanical performance. The safe insertion of anterograde the transpubic screw is important for patients with anterior pelvic ring fractures. This paper is to research the anatomical parameters of the anterograde transpubic screw corridor and evaluate the safety of anterograde transpubic screw placement assisted by the assembled navigation template.

METHODS

Fifty subjects with normal pelvic, 25 men and 25 women, age from 20 to 60 were enrolled, and their ilium were 3D reconstructed. The ilium was divided into zone I, zone II and zone III. Zone I and zone III was defined as medial and lateral to the obturator foramen, respectively. Zone II is located between zones I and III. The corridor A is formed by zone I and zone II and corridor B is formed by zone I, zone II and zone III. The diameter and length of the inner circle, the distance from the center of the inner circle to the posterior superior and to the inferior iliac spine of corridor A and corridor B were measured, respectively. Nine patients with pelvic fractures underwent anterograde transpubic screw and transverse sacroiliac screw placement assisted by the assembled navigation template and were retrospectively analyzed. Operation time, blood loss, incision length and fluoroscopy times were recorded. Grading score and Matta score were evaluated after surgery.

RESULTS

In the 50 subjects, the diameter of corridor A was 11.16 ± 2.13 mm, and that of corridor B was 8.54 ± 1.52 mm. The length of corridor A was 86.39 ± 9.35 mm, and that of corridor B was 117.05 ± 5.91 mm. The surface distance from the screw entry point to the posterior superior iliac spine in corridor A was 109.31 ± 11.06 mm, and that in corridor B was 127.86 ± 8.23 mm. The surface distance from the screw entry point to the posterior inferior iliac spine in corridor A was 91.16 ± 10.34 mm, and that in corridor B was 106.92 ± 7.91 mm. A total of 18 sacroiliac transverse screws and 11 anterograde transpubic screws were inserted assisted by assembled navigation templates for nine patients. The average operation time was 108.75 ± 25.71 min, the blood loss was 141.11 ± 50.21 ml, the incision length was 14 ± 4.62 cm, and the intraoperative fluoroscopy was 17.89 ± 4.01 times.

CONCLUSION

Transpubic screw corridor can be obtained by 3D reconstruction. For the majority of patients, the anterograde pubic ramus corridor accommodated a 6.5 mm diameter screw. It is safe to use anterograde transpubic screw placement assisted by an assembled navigation template.

Supraacetabular osseous corridor: defining dimensions, sex differences, and alternatives

INTRODUCTION

The supraacetabular (SA) corridor extends from the anterior inferior iliac spine to the posterior ilium and can safely accommodate implants to stabilize pelvic and acetabular fractures. However, quantitative analysis of its dimensions and characteristics have not been thoroughly described. This study seeks to define the dimensions, common constriction points, and any alternative trajectories that would maximize the corridor diameter.

METHODS

Computed tomography of 100 male and 100 female hemipelves without osseous trauma were evaluated. The corridor boundaries were determined through manual best-fit analysis. The largest intercortical cylinder within the pathway was created and measured. Alternative trajectories were tested within the SA boundaries to identify another orientation that maximized the diameter of the intercortical cylinder.

RESULTS

The traditional SA corridor had a mean diameter of 8.3 mm in men and 6.2 mm in women. This difference in diameter is due to a more S-shaped ilium in women. A larger alternative SA corridor was found that had a less limited path through the ilium and measured 11.3 mm in men and 9.9 mm in women. These dimensions are significantly different compared to those of the traditional SA corridor in both men and women.

CONCLUSIONS

In men, the SA corridor allows for the safe passage of most hardware used in pelvic and acetabular fractures. However, in women, the SA corridor is restricted by a more S-shaped ilium. An alternative trajectory was found that has a significantly larger mean diameter in both sexes. Ultimately, the trajectory of hardware will be dictated by the clinical scenario. When large implants are needed, especially in women, we recommend considering the alternative SA corridor.

Defining the iliac wing osseous fixation pathways: anatomy and implant constriction points

INTRODUCTION

Insertion of iliac wing implants requires understanding of the curvilinear shape of the ilium. This study serves to quantitatively identify the area of iliac inner-outer table convergence (IOTC), characterize the iliac wing osseous corridor, and define the gluteal pillar osseous corridor.

METHODS

Computed tomography scans of 100 male and 100 female hemipelves were evaluated. The iliac wing was studied using manual best-fit analysis of the bounds of the inner and outer cortices. The IOTC was defined as the location of the iliac wing with an intercortical width less than 5 mm. The shortest distance from the apex of the iliac crest to the superior border of the IOTC was defined as the iliac wing osseous corridor. Finally, the width of the gluteal pillar corridor from the gluteus medius tubercle to the ischial tuberosity was measured.

RESULTS

The IOTC is an elliptical area measuring 22.3 cm². All ilia had an area where the inner and outer cortices converged to an intercortical width of less than 5 mm; 48% converged to a single cortex. The shortest mean distance from the superior edge of the iliac crest to the beginning of the IOTC was 20.3 mm in men and 13.8 mm in women (p < 0.001). The gluteal pillar diameter averaged 5.3 mm in men and 4.3 mm in women (p < 0.001).

DISCUSSION

All ilia converge to a thin and frequently unicortical central region. A 4.5 mm iliac wing lag screw will not breach the cortex if it remains within 20 mm or 14 mm distal to the cranial aspect of the iliac crest in males and females, respectively. Not only is the gluteal pillar smaller than previously thought, in 41% of males and 73% of females, it is not be large enough for 5 mm implants.

CONCLUSION

This study quantitatively assesses the dimensions of the IOTC, the iliac crest osseous corridor, and the gluteal pillar. Overall, our findings provide improved understanding of the limits for implant use in the iliac wing as well as better appreciation of the complex osteology of the ilium. This will help surgeons to identify safe areas for implant placement and avoid inadvertent cortical penetration.

The Kocher-Langenbeck approach combined with robot-aided percutaneous anterior column screw fixation for transverse-oriented acetabular fractures: a retrospective study

Objective

Transverse-oriented acetabular fractures (TOAFs), including transverse, transverse with posterior wall and T-shaped fractures, are always challenging for double-column reduction and fixation with minimally invasive method. The purpose of this study is to compare the therapeutic effects of robot-aided percutaneous anterior column screw fixation versus minimally invasive anterior plate fixation for TOAFs based on the Kocher-Langenbeck (K-L) approach.

Methods

Patients suffering TOAFs that were fixed by robot-aided percutaneous anterior column screw fixation or minimally invasive anterior plate fixation associated with posterior fixation via the K-L approach were divided into two groups: group A (screw fixation) and group B (plate fixation). Surgical time, blood loss, incision length for anterior fixation and complications were recorded. Fracture reduction quality was evaluated using criteria described by Matta. Fracture healing was assessed on the series of pelvic radiographs at each follow-up. Functional outcomes were investigated using the modified Postel Merle D’Aubigne score at the final follow-up.

Results

Twenty-nine patients with TOAFs, including 12 patients in group A and 17 patients in group B, were evaluated for study eligibility. The mean surgical time of anterior fracture fixation was 18.7 ± 4.6 min in group A and 33.4 ± 5.0 min in group B (P < 0.001). The amount of intraoperative blood loss was 615.6 ± 178.7 ml in group A and 719.3 ± 199.0 ml in group B (P < 0.001). Incision length for anterior fixation was 9.0 ± 1.8 mm in group A and 81.2 ± 7.3 mm in group B (P < 0.001). The complications related to the surgery of anterior column only occurred in group B (lateral femoral cutaneous nerve palsy in 1 patient and groin discomfort in 1 patient). No significant differences in reduction quality, hospital stay, fracture healing time and functional results were noted between the two groups.

Conclusion

The K-L approach combined with robot-aided anterior column screw fixation is a safe and effective option for TOAFs. Compared with minimally invasive anterior plate fixation, robot-aided screw fixation has obvious advantages on surgical time, blood loss, and invasiveness. The K-L approach combined with minimally invasive anterior plate fixation can also be a reliable alternative for TOAFs, with the similar reduction quality and functional results.

Anatomical evaluation of the transpubic screw corridor based on a 3D statistical model of the pelvic ring

Retrograde transpubic screw fixation is a common procedure for the treatment of anterior pelvic ring fractures. With its sparing surgical approach and significant pain relief after screw fixations allowing early mobilisation, it has gained importance especially in the treatment of insufficiency fractures in elderly patients. However, positioning of transpubic screw osteosynthesis is not always possible due to narrowness and curvature of the screw corridor. The aim of the present study was to evaluate availability and length of the screw corridor using a 3D statistical model of the pelvic ring consisting out of 150 uninjured pelves. Virtual bore probes with a diameter of 7.5 mm were analysed as to accessibility, length and grey value distribution in Hounsfield Unit (HU). A transpubic corridor with a diameter of ≥ 7.5 mm was available in 185 of 300 investigated superior pubic rami with mean screw length of 131.7 mm. Accessibility of the screw corridor was higher in males than in females. However, screw length showed no systematic differences between the sexes or ethnicities. Analysis of the grey value distribution demonstrated the strongest bone to be located at the lateral ilium and the supraacetabular region.

[Digital study of the ideal position of lag screw internal fixation in the anterior column of the acetabulum]

Objective

To find the ideal position of lag screw internal fixation in the anterior column of acetabulum by digital technology, and measure its related parameters, so as to improve the accuracy of lag screw implantation.

Methods

The CT scan data of 266 semi-pelvic raw in 133 cases (78 males and 55 females, aged 18-65 years old with an average age of 42 years) were collected between January 2019 and January 2020 to compose three-dimensional models. According to the relationship between the peripheral bone cortex of the anatomical channel and the lag screw, a new standard for the ideal position of lag screw fixation in the anterior column of acetabulum was proposed to simulate the implantation of the screw. After the screw was in the ideal position, the following indicators were measured: the maximum allowable diameter of the virtual screw (the diameter of the cylinder up to the new standard, R), the length (the distance between the center of the nail point on both sides, L); the position of the retrograde nail point (the interval between the nail insertion points and the midpoint of the pubic symphysis and the pubic tubercle, respectively, D1 and D2) and the position of the antegrade nail insertion point (the distance between the nail insertion point and the anterior superior iliac spine, the major ischial notch, and the vertical distance between the nail insertion point and the apex of the posterior upper edge of the acetabulum, respectively, D3, D4, D5); and the direction of the virtual screw at the ideal position (the angle between the screw and the horizontal plane, sagittal plane, and coronal plane, respectively, ∠β, ∠γ, ∠δ) were calculated.

Results

The maximum allowable diameter of virtual screws was 5.70-14.10 mm for males, with an average of 9.25 mm; for females, it was 4.40-10.40 mm with an average of 7.29 mm. The antegrade insertion point of the anteroposterior acetabular lag screw was located at 2.0-2.5 cm above the apex of the acetabulum, which was almost the same distance from the anterior superior iliac spine and the ischial notch, about 5 cm; the insertion point of the retrograde implant was located at the pubic bone 2.5-3.0 cm below the nodule. When the acetabular anterior column screw was in the ideal position, there was no significant difference in the comparison of ∠β and ∠γ between the male and the female ( P>0.05), and the differences in the other indicators were significant ( P<0.05). Except for D4 and ∠β showing no significant difference between the left and right sides ( P>0.05), the differences in the other indicators were significant ( P<0.05).

Conclusion

In the bony channel of the anterior column of the acetabulum, all males can accommodate screws with a diameter of <5.70 mm, and females can accommodate screws with a diameter of <4.40 mm. The anterograde or retrograde screw insertion points are different for male and female. The use of digital technology to individually measure the appropriate screw parameters can improve the accuracy and stability of the lag screw internal fixation for acetabular anterior column fractures.

Obturator Oblique and Pubic Ramus Inlet Views Can Better Guide the Insertion of an Anterior Column Acetabular Screw

OBJECTIVE

The objective of the present paper was to investigate the value of obturator oblique and pubic ramus inlet views in guiding anterior column acetabular screw insertion.

METHODS

We collected pelvic CT scans at the diagnostic imaging center of our hospital between 2017 and 2019. Virtual three-dimensional (3D) models of the pelvis were created based on the CT scans. Then the transparency was adjusted to 30%. Two identical copies of the 3D model data were made. 3D model replications were divided into a control group and an experimental group. In the control group, the screw was inserted into the anterior acetabular column using obturator-outlet and iliac-inlet views. In the experimental group, the screw was guided under obturator oblique and pubic ramus inlet views. Based on whether the screw penetrated the hip joint and/or exited the pubic ramus, models were divided into three grades. Grade I: the screw travels completely within the anterior column bone corridor; Grade II: the screw exits the superior pubic ramus, but the length of the screw outside the channel does not exceed 1/2 of the anterior column; Grade III: the screw exits the superior pubic ramus and the length of the screw outside the corridor exceeds 1/2 of the anterior column. We compared the screw placement quality of the two groups and analyzed differences between genders. In addition, the distance between the screws and the acetabulum was recorded and compared among the two groups.

RESULTS

A total of 110 hemipelves were selected, including those of 80 men and 30 women, with an average age of 46.76 ± 14.26 years. In the control group, the screw quality of 64 models (58.2%) was Grade I. In the experimental group, 94 models (85.5%) had Grade I screw placement quality. Grade II screw placement quality accounted for 18.2% of the control group and 7.3% of the experimental group. In the control and the experimental groups, there were 26 and 8 cases with Grade III screw placement quality, respectively. The quality of screw placement in the experimental group was significantly better than that in control group, and the difference between the two groups was statistically significant (P < 0.01). The distance between the screw and the acetabulum in the control group and experimental group was 0.92 ± 0.49 mm and 2.78 ± 1.15 mm, respectively. The difference between the two groups was statistically significant.

CONCLUSION

Anterior column acetabular screws can be inserted successfully and more accurately using the obturator oblique and pubic ramus inlet views.

Biomechanical Analysis of Retrograde Superior Ramus Screw Fixation Constructs

OBJECTIVE

To investigate the biomechanical performance of different size and length retrograde superior ramus screws.

MATERIALS AND METHODS

A vertical superior ramus fracture was created in osteoporotic composite hemipelvis bone models (Sawbones, Vashon Island, WA). After reduction, 4 fixation groups were created by inserting either a solid 4.5 mm (Depuy Synthes, Paoli, PA) or cannulated 7.0 mm screw (Zimmer, Warsaw, IN) of either 80 mm (short) or 140 mm (long) in length. An intact and an unstabilized osteotomy group were also created. Samples underwent cyclic loading for 5000 cycles with data acquisition at regular intervals. At the end of cyclic loading, load to failure was performed.

RESULTS

The displacement after 5000 cycles for 4.5 mm short screws was significantly greater than 4.5 mm long and 7.0 mm short screws. At 5000 cycles, the 4.5-mm short screws had a significantly lower stiffness and lower load to failure than all other screws and were not different from the osteotomy model.

CONCLUSIONS

Short 4.5-mm screws demonstrated increased displacement, lower stiffness, and decreased load to failure compared with all other screws. The biomechanical performance of 4.5-mm short screws was no different than unstabilized controls. Longer bicortical screw fixation is suggested when possible. Additional biomechanical and clinical studies are needed to fully understand the significance of these findings.

The Stoppa combined with iliac fossa approach for the treatment of both-column acetabular fractures

Background

At present, the choice of surgical approach for both-column fractures is still controversial. The purpose of this study was to explore the efficacy of the Stoppa combined with iliac fossa (S+IF) approach in the treatment of both-column fractures.

Methods

In this retrospective case series, 76 patients were included in the study from 2014 to 2018. They were divided into two groups according to the surgical approaches. The differences of intraoperative blood loss, operative time, quality of reduction, clinical outcome, and perioperative complications were compared between the two groups.

Results

All patients had undergone the IL approach or the S+IF approach. The average operative time was 156.2 min (110~210 min) in group I and 126.5 min (80~180 min) in group II (P < 0.001). The average blood loss in group I was 784.1 ml, while the average blood loss in group II was 625.3 ml (P = 0.007). According to Matta’s criteria, 28 cases obtained anatomic reduction and 12 cases got imperfect reduction in group I; 21 cases obtained anatomic reduction and 7 cases got imperfect reduction in group II (P > 0.05). The clinical outcome (excellent to good) was 66% in group I versus 69% in group II (P > 0.05). The complication rates were 18.2% in group I and 12.5% in group II (P > 0.05).

Conclusions

As a minimally invasive surgical approach, the S+IF approach is a valuable alternative to the IL approach for the treatment of both-column acetabular fractures if these two anterior approaches can achieve fracture exposure, reduction, and fixation.

New Concealed-Incision Extrapelvic Approach for Pubic Symphysis Diastasis and Parasymphyseal Fractures: Preliminary Results

BACKGROUND

The Pfannenstiel approach, which provides good surgical exposure, has been used for the treatment of pubic symphysis diastasis and parasymphyseal fractures. However, it requires a medium-length incision and moderate soft-tissue dissection, resulting in potential damage to anatomical structures and inferior aesthetic outcomes. Here, we introduce a new concealed-incision extrapelvic approach for the internal fixation of pubic symphysis diastasis and parasymphyseal fractures.

METHODS

We retrospectively reviewed the records of 8 patients with pubic symphysis diastasis and parasymphyseal fractures that had been treated via the concealed-incision extrapelvic approach (the "Fu-Liu" approach). All patients presented for treatment during the period from January 2017 to November 2017. Six of the 8 patients had anterior column fractures, 1 patient had a double-column fracture, and 1 patient had parasymphyseal fractures. Operative time, the amount of blood loss, and postoperative radiographic and computed tomography (CT) findings were recorded. The degree of fracture-healing, complications, function, and satisfaction with the skin incisions were also evaluated.

RESULTS

All patients were followed for at least 21 months (range, 21 to 30 months). Postoperative radiographs and CT scans showed good positioning of plates and screws. The average time before surgery, operative time, and intraoperative blood loss (and standard deviation) were 7.8 ± 3.25 days, 41.9 ± 8.99 minutes, and 18.8 ± 7.8 mL, respectively. No complications (including internal fixation failure, vascular injury, nerve palsy, wound infection, and hernia) occurred in any of the patients, and all patients were satisfied with the appearance of the scar.

CONCLUSIONS

We can effectively stabilize pubic symphysis diastasis and parasymphyseal fractures with use of the Fu-Liu approach, which can also enable retrograde anterior column screw placement. The Fu-Liu approach is simple, safe, and minimally invasive, and the aesthetic outcome is more acceptable than that associated with the Pfannenstiel approach.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Posterior wall fractures associated with both-column acetabular fractures can be skilfully ignored

INTRODUCTION

Posterior wall fractures may be associated with both-column acetabular fractures. Considering the differences in the pattern of these fractures in contrast to isolated posterior wall fractures, it is currently unclear whether they can be ignored or need to be addressed surgically.

HYPOTHESIS

Stable posterior wall fractures can be skilfully ignored in patients with both-column acetabular fractures operated by an ilioinguinal approach.

MATERIAL AND METHODS

We retrospectively reviewed 49 consecutive patients who were treated for both-column acetabular fractures between the years 2009 and 2018. Considering the association of posterior wall fractures, we divided the cohort into two groups: Group 1 (n=29): absence of posterior wall fractures; and Group 2 (n=20): presence of posterior wall fractures, subsequently treated while skilfully ignoring stable posterior wall fracture according to our criteria. Intergroup comparison of radiologic and clinical outcomes and multiple linear regression for predictors of clinical outcomes were analysed.

RESULTS

No significant intergroup difference in quality of reduction, post-traumatic osteoarthritis grade, or clinical outcome was noted. Poor post-traumatic osteoarthritis grade and poor quality of reduction of both acetabular columns were significant predictors of clinical outcomes in patients with both-column acetabular fractures. Whether posterior wall fracture was associated and skilfully ignored was unrelated to clinical outcomes.

DISCUSSION

Posterior wall fractures associated with both-column acetabular fractures can be successfully ignored if the posterior wall fragment is adequately attached to the acetabulum through the labrocapsular complex of the hip joint, and the hip-joint-congruency in the presence of<2-mm step-off and 3-mm gap.

LEVEL OF PROOF

III, prognostic.

Computer navigation-assisted minimally invasive percutaneous screw placement for pelvic fractures

Pelvic fractures are often caused by high-energy injuries and accompanied by hemodynamic instability. Traditional open surgery has a large amount of bleeding, which is not suitable for patients with acute pelvic fracture. Navigation-guided, percutaneous puncture-screw implantation has gradually become a preferred procedure due to its advantages, which include less trauma, faster recovery times, and less bleeding. However, due to the complexity of pelvic anatomy, doctors often encounter some problems when using navigation to treat pelvic fractures. This article reviews the indications, contraindications, surgical procedures, and related complications of this procedure for the treatment of sacral fractures, sacroiliac joint injuries, pelvic ring injuries, and acetabular fractures. We also analyze the causes of inaccurate screw placement. Percutaneous screw placement under navigational guidance has the advantages of high accuracy, low incidence of complications and small soft-tissue damage, minimal blood loss, short hospital stays, and quick recovery. There is no difference in the incidence of complications between surgeries performed by new doctors and experienced ones. However, computer navigation technology requires extensive training, and attention should be given to avoid complications such as screw misplacement, intestinal injury, and serious blood vessel and nerve injuries caused by navigational drift.

Minimal-invasive stabilization of anterior pelvic ring fractures with retrograde transpubic screws

BACKGROUND

In the vast majority of patients with pelvic ring lesions, there is a combination of fractures of the posterior and anterior pelvic ring. Anterior fractures are painful and contribute to loss of stability of the pelvic ring. For these reasons, stabilization of pubic rami fractures is recommended together with posterior pelvic ring fixation. Retrograde transpubic screw osteosynthesis enjoys increasing acceptance due to its minimal invasive technique and adequate stability.

PATIENTS AND METHODS

We retrospectively reviewed the results of 158 retrograde transpubic screw osteosyntheses in 128 patients with pelvic ring lesions including a pubic ramus fracture. Sixty-three patients suffered a high-energy injury, 65 a fragility fracture of the pelvis.

RESULTS

One hundred and forty-six screws (92.4%) were inserted through a percutaneous procedure. There were no vascular, neurological or urological complications. Fifty-nine screws (39%) yielded an excellent reduction with less than one cortical width of displacement. Slight secondary displacement was seen in 33 of these fractures (55.9%). Early surgical complications were seen in 16 screws (10.1%): suboptimal pathway in 10, local hematoma in 4 and local infection in 3. Early revision surgery was done in 7 screws (4.4%). Median follow-up was 27.6 weeks, 83 screws (52.5%) had a follow-up of more than 6 months. During follow-up, 7.6% of screws loosened. Operative revision was performed in 13%. 75 fractures (90.3%) with a follow-up of ≥ 6 months showed radiographic evidence of healing. There was no difference in the healing rate of high-energy and fragility fractures. Nonunion rate was not dependent on the quality of primary reduction, secondary displacement, or screw loosening. Infection (p 0.001) and surgery ≥ 6 months after trauma (p 0.02) more often led to nonunion.

CONCLUSION

Retrograde transpubic screw osteosynthesis is a reliable method for splinting pubic rami fractures in high and low energy pelvic trauma. Although a slight secondary fracture displacement is seen in most cases, it does not affect fracture healing. Retrograde transpubic screw is a adequate minimal-invasive osteosynthesis to stabilize the anterior pelvic ring, especially in fragility fracture of the pelvis. Delayed operation (> 6 months) and infection show higher rate of nonunion.

Morphometric analysis of the anterior column of the acetabulum and safety of intramedullary screw fixation for its fractures in Indian population: a preliminary report

INTRODUCTION

Morphometric variations of the anterior column of the acetabulum have been described in the literature for its complex structure, which can influence the safe containment of intramedullary screw for fixation of its fractures. The purpose of this CT-based study is to present a preliminary report on the morphometric variations and safety of intramedullary screw fixation of the anterior column of the acetabulum in the Indian population.

METHODS

CT-based data from 102 uninjured pelves were retrospectively analyzed in iPlanⓇ BrainLab AG, Feldkirchen, Germany. Narrowest zones around acetabulum and superior pubic ramus were measured. We calculated the axis of the anterior column of the acetabulum by joining the centres of these narrowest zones. Standard screws trajectories were directed along this axis. Screw length up to the first cortical perforation, the distance of the exit point from the pubic symphysis, and the length of the anterior column up to the pubic tubercle were measured.

RESULTS

The osseous corridor of the anterior column of acetabulum had variable cross-section along its length with two constriction zones, first in the acetabular region and second in the superior pubic ramus. Only 54% of our cases allowed safe applicability of 6.5-mm-diameter screw trajectories with safety margin of 2 mm on either side of the screw. Significant morphometric and screw applicability-related differences were observed among male and female cases with males having a wider osseous corridor in general. Elimination of safety margin results in a significant increase in the screw applicability.

CONCLUSION

The osseous corridor of the anterior column varies in its dimensions from individual to individual. Standard screws of 6.5-mm and 7.3-mm diameters may not be safe for intramedullary screw fixation in every patient and carry a risk of cortical violation when a 2 mm of width around the screw is considered as a safety margin. However, with a precise screw placement within the extents of the cortices of the anterior column, 6.5-mm screws can be applied in most of the female cases and 7.3-mm screws can be applied in most of the male cases for anterior column fixation.

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.

Intramedullary Fixation Techniques for the Anterior Pelvic Ring

The superior ramus is an irregularly shaped, undulating, and curvilinear osseous structure that can provide an osseous conduit for intramedullary screws. A wide spectrum of variability between the curve and obliquity of the superior ramus osseous fixation pathway (OFP) exists in both the anteroposterior and the coronal planes. A detailed understanding of the osseous topography and how it correlates with fluoroscopic imaging is mandatory. Obtaining the correct intraoperative inlet and combined obturator oblique-outlet fluoroscopic views specific to each patient's anatomy is necessary for safe implant insertion. Intramedullary screws can be inserted in either an antegrade or a retrograde direction depending on a number of variables, including fracture location, the proximity of patient's external genitalia to the skin insertion side, and the possible impact of thigh girth on the surgeons hand position. Multiple screw insertion techniques are possible, but a simple and reproducible technique is described. The size and number of screws that can be inserted is variable, differs between surgeons, but is ultimately dependent on the cortical limits of the superior ramus OFP. Standard screw insertion techniques are successful in most patients. If the osseous corridor or external anatomy impedes standard insertional techniques, several modifications exist that can allow successful screw insertion. A thorough understanding of each patient's anatomy, injury, and precise surgical technique with the appropriate fluoroscopic views are required to safely place intraosseous intramedullary implants into the superior ramus OFP.

Percutaneous fixation of acetabular fractures

The objective of surgery for acetabular fractures is to achieve precise reduction to restore joint congruence, fix internal bone fragments, avoid displacement of the fracture and allow rapid rehabilitation.Open reduction and internal fixation is the benchmark method for displaced acetabular fractures, but open reductions can increase morbidity, causing neurovascular injury, blood loss, heterotopic bone formation, infection and poor wound healing.An anatomical reduction with a gap of 2 mm or less is a predictor of good joint function and reduced risk of post-traumatic osteoarthritis.The percutaneous approach is associated with fewer complications than open techniques, but acetabular geometry makes percutaneous screw insertion a challenging procedure.The percutaneous technique is recommended for non-displaced or slightly displaced fractures, and in obese, osteoporotic and elderly patients who cannot receive total joint arthroplasty.We recommend the use of intramedullary cannulated screws.Fracture reductions are achieved by manual traction of the affected bones. If some fracture displacement remains, accessory windows can be used to introduce a ball spike pusher, a hook or a Steinmann pin which can be used as a joystick to rotate the fracture.In this paper, we describe the accessory windows for the anterior column, the quadrilateral plate and the posterior column. We detail the position, direction and kind of screws used to stabilize the anterior and posterior columns. Cite this article: EFORT Open Rev 2018;3 DOI: 10.1302/2058-5241.3.170054.

Minimally invasive treatment of both-column acetabular fractures through the Stoppa combined with iliac fossa approach

Both-column fractures are the most complicated group of acetabular fractures. Although great progress of surgical technique has been made, the choice of approach is controversial. All the fragments could be exposed and managed through combined ilioinguinal and Kocher-Langenbeck (IL+KL) approaches, which has been widely used to conduct the both-column fractures. However, the clinical popularization may be restricted for high rate of complication. Most internal area of the hemipelvis could be exposed through Stoppa combined with iliac fossa (S+IF) approach. The majority of both-column fractures were managed through IL+KL approaches or S+IF approach in our institution. The comparison of the two surgical methods was done in this study. The purpose is to examine whether S+IF approach could achieve the satisfactory reduction and fixation for both-column fractures.

The Retrograde-Antegrade-Retrograde Technique for Successful Placement of a Retrograde Superior Ramus Screw

Stabilization of pelvic ring injuries and certain acetabular fractures using percutaneous techniques is becoming increasingly more common. Intramedullary superior ramus screw fixation is beneficial in both injury types. While implants can be placed in an antegrade or retrograde direction, parasymphyseal ramus fractures benefit from retrograde implant insertion. In some patients, the parabolic osseous anatomy or obstructing soft tissues of the anterior pelvis or thigh can prevent appropriate hand and instrumentation positioning for appropriate retrograde ramus screw insertion through the entire osseous fixation pathway. Instead of abandoning medullary fixation, we propose a technique utilizing cannulated screws to successfully place retrograde screws in this distinct clinical scenario.

Accurate fixation of plates and screws for the treatment of acetabular fractures using 3D-printed guiding templates: An experimental study

OBJECTIVE

To investigate the feasibility of the use of 3D-printed guiding templates for accurate placement of plates and screws for internal fixation of acetabular fractures.

METHODS

3D models of the pelvises of 14 adult cadavers were reconstructed using computed tomography (CT). Twenty-eight acetabular fractures were simulated and placement positions for plates and screw trajectories were designed. Bending module was obtained by 3D cutting; guiding template was manufactured using 3D printing, and the plate was pre-bent according to the bending module. Plates and screws were placed in cadaveric pelvises using the guiding template, and 3D model was reconstructed using CT. The designed and real trajectories were matched using 3D registration including the coordinates (entry and exit points) of designed trajectory. The number of qualified points with different accuracy levels was compared using Chi-squared test.

RESULTS

Sixty-four plates and 339 screws were placed with no cortical breach. The absolute difference of the X, Y, and Z coordinates between the designed and real entry points were 0.52±0.45, 0.43±0.36, and 0.53±0.44mm, respectively. The corresponding values for the exit points were 0.83±0.67, 1.22±0.87, and 1.26±0.83mm, respectively. With an accuracy degree ≥1.9mm for the entry points and ≥3.8mm for the exit points, there was no significant difference between the designed and the real trajectories.

CONCLUSION

The 3D-printed guiding template helped achieve accurate placement of plates and screws in the pelvis of adult cadavers.

[Percutaneous internal fixation of pelvic fractures. German version]

BACKGROUND

Percutaneous internal fixation of pelvic fractures is increasing in popularity with multiple new techniques reported.

OBJECTIVES

The purpose of this article is to outline the imaging, indication, planning, equipment, surgical technique and complications of these methods.

METHODS

A review of the literature is provided and the techniques for anterior and posterior pelvic stabilization are discussed.

RESULTS

High-quality preoperative CT scans are essential in planning for this technique. The anterior internal fixator ("InFix") is an effective method for stabilizing the anterior ring and should be usually used in conjunction with posterior fixation. Good technique avoids neurovascular injury, which can be a devastating complication. The retrograde anterior column screw (RACS) is a technique that can be used in most patients, although in smaller patients smaller screw diameters may be needed. The entry point for the screw is more lateral in women than men. Iliosacral screws (ISS) are an effective method of posterior stabilization and can be placed using 2D or 3D fluoroscopy, computer navigation or CT navigation.

CONCLUSION

Percutaneous fixation of pelvic fractures requires high-quality imaging and can be aided by computer navigation. Safe techniques are reproducible; however, not all patients and fracture patterns can be treated using these techniques.

Anterograde Fixation Module for Posterior Acetabular Column Fracture: Computer-Assisted Determination of Optimal Entry Point, Angle, and Length for Screw Insertion

BACKGROUND The aim of this study was to provide valid data for a plate-screw fixation model for fractured posterior-anterior columns of the acetabulum. MATERIAL AND METHODS Nineteen cadaveric bony hemi-pelvis specimens were obtained and 50 healthy adults were enrolled. The modified Stoppa approach and computed tomography (CT) imaging were used to collect the measured parameter data of the module. RESULTS The measured parameter data were as follows: OP, 0.96±0.32 cm in females and 0.92±0.16 cm in males (P>0.05); PI, 0.98±0.28 cm in females, and 0.75±0.23 cm in males (P>0.05); Ðϴ, 59.68°±6.28° in females and 56.75°±3.22° in males (P>0.05); and Ðφ, 41.27°±2.76° in females and 34.31°±2.78° in males (P<0.05). The corresponding CT image data were as follows: PI, 1.08±0.22 cm in females and 0.85±0.27 cm in males (P>0.05); OP, 1.06±0.29 cm in females and 1.12±0.24 cm in males (P>0.05); Ðϴ, 55.33°±4.00° in females and 55. 50°±3.43° in males (P>0.05); and Ðφ was 39.21°±2.45°in females and 35.58°±2.31°in males (P<0.05). No significant difference with respect to sex and side existed between specimens and healthy adults (P>0.05). CONCLUSIONS The measured parameter data obtained in healthy adults and cadaveric specimens provided an anatomic basis for the designation of the guide module, and thus confirmed the accuracy and safety of screw placement in fractured columns of the acetabulum.

An Effective and Feasible Method, "Hammering Technique," for Percutaneous Fixation of Anterior Column Acetabular Fracture

Objective. The objective of this study was to evaluate the effectiveness and advantages of percutaneous fixation of anterior column acetabular fracture with “hammering technique.” Materials and Methods. We retrospectively reviewed 16 patients with percutaneous fixation of anterior column acetabular fracture with “hammering technique.” There were 11 males and 5 females with an average age of 38.88 years (range: 24–54 years) in our study. Our study included 7 nondisplaced fractures, 6 mild displaced fractures (<2 mm), and 5 displaced fractures (>2 mm). The mean time from injury to surgery was 4.5 days (range: 2–7 days). Results. The average of operation time was 27.56 minutes (range: 15–45 minutes), and the mean blood loss was 55.28 mL (range: 15–100 mL). The mean fluoroscopic time was 54.78 seconds (range: 40–77 seconds). The first pass of the guide wire was acceptable without cortical perforation or intra-articular perforation in 88.89% (16/18) of the procedures, and the second attempt was in 11.11% (2/18). Conclusion. Our study suggested that percutaneous fixation of anterior column acetabular fracture with “hammering technique” acquired satisfying surgical and clinical outcomes. It may be an alternative satisfying treatment for percutaneous fixation of anterior column acetabular fracture by 2D fluoroscopy using a C-arm with less fluoroscopic time.

Experimental study on treatment of acetabular anterior column fractures: applyment of a minimally invasive percutaneous lag screw guide apparatus

BACKGROUND

The aim of this study was to design a new minimally invasive percutaneous lag screw guide apparatus and to verify its adjuvant treatment of acetabular anterior column fracture on pelvis specimens.

METHODS

This guide apparatus was self-developed based on the principles of "two points form a line" and "Rectangle". Using C-arm fluoroscopy, this guide apparatus was used to conduct minimally invasive percutaneous lag screw internal fixation of acetabular anterior column fractures. Ten hollow lag screws were placed into 5 pelvis specimens.

RESULT

Result showed no sign of any screws puncturing the cortex or entering into the hip joint on radiological assessment. The cross-section reconstructed vertical distance to the screw, on the cross-section acetabular notch and the cross-section of the screw where the distance of between the screw and the iliopectineal line's arc roof was at its shortest, indicate that at all points (T, R-r) under the line with an inclination of 1 (namely T = R-r) the screw is within the cortex and does not puncture the acetabula anterior column or enter into the hip joint.

CONCLUSIONS

We may conclude that this self-developed guide apparatus solves the screw precision problem during the treatment of acetabular anterior column fractures through a minimally invasive percutaneous lag screw.

Comparison of anterograde versus retrograde percutaneous screw fixation of anterior column acetabular fractures

PURPOSE

Percutaneous screw fixation is an effective technique in addressing minimally displaced anterior column acetabular fractures. The aim of this study is to evaluate the ease of percutaneous screw insertion for acetabular anterior column fracture, as it pertains to anterograde versus retrograde insertion techniques.

METHOD

From 2009 to 2013, CT imaging from 30 adult volunteers (15 males, 15 females) without history of pelvic disruption and/or morphologic abnormalities were evaluated. From these images, virtual 3D pelvic models were generated. The differences area of screw starting points, limitation position of anterior column screws, and range of screw directions were analyzed.

CONCLUSION

We found in our analysis that anterograde and retrograde had not only variations in their starting points, but differences in areas of insertion. Typically, anterograde portals have a larger area for insertion. Additionally, given the limitations we noted in screw position and the severity of the acetabular fractures, this will allow the treating surgeon to determine the most optimal technique for percutaneous anterior column screw fixation.

RESULTS

In our analysis, we found two areas for effective percutaneous anterograde insertion and one area for effective retrograde insertion. They both possess geometries with different shapes. Additionally, the area of anterograde insertion is larger than the retrograde area of insertion. The limitations in screw positions were shown in the AP, inlet, outlet, iliac oblique, obturator oblique, and lateral views. The direction range between superior and inferior and between medial and lateral were measured and recorded. In area of anterograde, the angle between the superior and inferior limits was 29.2° ± 2.7°, while the angle limit between medial and lateral was 18.5° ± 1.8°. In area of retrograde, the angle between the superior and inferior limits was 8.32° ± 1.3°, while the angle limit between medial and lateral was 7.5° ± 0.8°

Axial perspective to find the largest intraosseous space available for percutaneous screw fixation of fractures of the acetabular anterior column

OBJECTIVE

To find the largest screw path in the acetabular anterior column using a novel method of axial perspective and test the clinical feasibility of the anterior column axial view projection.

METHODS

3D models with the inner triangular patches deleted were created from the pelvic CT scan data of 58 normal pelvises. The transparency of each 3D model was downgraded at the axial perspective (the view perpendicular to the cross section of the anterior column axis) so that a translucent area was seen clearly. The orientations of each 3D model were adjusted until a triangle-like translucent area that could accommodate the largest virtual screw (Screw I) was present and then an ellipse-like translucent area that could accommodate the two largest virtual screws (Screw II) was present. The maximum diameter, direction of Screw I and the maximum diameter Screw II were measured. Clinical feasibility of the axial view projection was next tested in five cadaveric specimens.

RESULTS

The mean maximum diameters of Screw I and Screw II were 11.20 ± 1.73 (7.80-14.60 mm) and 8.71 ± 0.91 (6.60-10.60 mm), respectively. The angles of Screw I to the transverse, coronal and sagittal planes were 41.16° ± 4.59°, 18.18° ± 1.15° and 44.33° ± 4.31°, respectively. Translucent areas were successfully observed in all the cadaveric hemi-pelves and guide pins were successfully inserted in all the cadaveric hemi-pelves with the assistance of the anterior column axial view projection without cortex penetration or joint violation.

CONCLUSIONS

The acetabular anterior column could safely accommodate not only one 7.3-mm screw, but also two 6.5-mm screws. The anterior column axial projection may be clinically feasible.

Sex-specific differences of the infraacetabular corridor: a biomorphometric CT-based analysis on a database of 523 pelves

BACKGROUND

An infraacetabular screw path facilitates the closure of a periacetabular fixation frame to increase the plate fixation strength in acetabular fractures up to 50%. Knowledge of the variance in corridor sizes and axes has substantial surgical relevance for safe screw placement.

QUESTIONS/PURPOSES

(1) What proportion of healthy pelvis specimens have an infraacetabular corridor that is 5 mm or larger in diameter? (2) Does a universal corridor axis and specific screw entry point exist? (3) Are there sex-specific differences in the infraacetabular corridor size or axis and are these correlated with anthropometric parameters like age, body weight and height, or the acetabular diameter?

METHODS

A template pelvis with a mean shape from 523 segmented pelvis specimens was generated using a CT-based advanced image analyzing system. Each individual pelvis was registered to the template using a free-form registration algorithm. Feasible surface regions for the entry and exit points of the infraacetabular corridor were marked on the template and automatically mapped to the individual samples to perform a measurement of the maximum sizes and axes of the infraacetabular corridor on each specimen. A minimum corridor diameter of at least 5 mm was defined as a cutoff for placing a 3.5-mm cortical screw in clinical settings.

RESULTS

In 484 of 523 pelves (93%), an infraacetabular corridor with a diameter of at least 5 mm was found. Using the mean axis angulations (54.8° [95% confidence interval {CI}, 0.6] from anterocranial to posterocaudal in relation to the anterior pelvic plane and 1.5° [95% CI, 0.4] from anteromedial to posterolateral in relation to the sagittal midline plane), a sufficient osseous corridor was present in 64% of pelves. Allowing adjustment of the three-dimensional axis by another 5° included an additional 25% of pelves. All corridor parameters were different between females and males (corridor diameter, 6.9 [95% CI, 0.2] versus 7.7 [95% CI, 0.2] mm; p<0.001; corridor length, 96.2 [95% CI, 0.7] versus 106.4 [95% CI, 0.6] mm; p<0.001; anterior pelvic plane angle, 54.0° [95% CI, 0.9] versus 55.3° [95% CI, 0.8]; p<0.01; sagittal midline plane angle, 4.3° [95% CI, 0.6] versus -0.3° [95% CI, 0.5]; p<0.001).

CONCLUSION

This study provided reference values for placement of a 3.5-mm cortical screw in the infraacetabular osseous corridor in 90% of female and 94% of male pelves. Based on the sex-related differences in corridor axes, the mean screw trajectory is approximately parallel to the sagittal midline plane in males but has to be tilted from medial to lateral in females. Considering the narrow corridor diameters, we suggest an individual preoperative CT scan analysis for fine adjustments in each patient.

Three-dimensional fluoroscopy-navigated percutaneous screw fixation of acetabular fractures

OBJECTIVE

Anatomic reduction and articular restoration after acetabular fractures occur (Ac-Fxs) are accepted predictors for good function and slow progression of posttraumatic osteoarthritis of the hip. The aim of this study was to retrospectively analyze Ac-Fxs, which were treated with closed reduction and percutaneous (three-dimensional) fluoroscopy-based navigated screw fixation.

DESIGN

Level 4, retrospective clinical and radiographic assessment.

SETTING

Level 1 trauma center.

PATIENTS

Twelve patients (male/female: 9/3; mean age: 60 years; range: 16-80 years) with moderately displaced Ac-Fxs were included.

INTERVENTION

In enrolled patients, the treatment involved percutaneous three-dimensional fluoroscopy-based navigated lag screw positioning. Closed reduction was achieved by lag screws, or reduction was aided by the insertion of percutaneous Schanz pins.

MAIN OUTCOME MEASUREMENTS

The quality of the reduction and screw positions were assessed using intraoperative and postoperative computed tomography scans. Functional outcome was assessed using the Harris hip score, the visual analog scale for pain, and the Tegener activity scale.

RESULTS

A total of 22 periacetabular screws were placed (mean: 1.8 ± 1.1 screws/patient, range: 1-5). The mean follow-up was done for 30 (16-72) months. The postoperative reduction was anatomical in all patients, and the mean fracture displacement was significantly reduced (gap: 4.1 ± 1.8 mm to 0.4 ± 0.7 mm/step: 1.4 ± 0.6 mm to 0.2 ± 0.4 mm). No secondary dislocations or malunions/nonunions were found. All screws correctly addressed the fracture morphology and corresponded to preoperative planning. The Harris hip score, the visual analog scale (motion), and Tegener activity scale showed excellent to very good results (92.4 ± 6.8, 1.9 ± 1.3, and 3.8 ± 1.6, respectively).

CONCLUSIONS

The navigated, percutaneous screw fixation of selected Ac-Fxs is a promising method that allows for closed reduction and fixation while obtaining a very good radiographic and functional outcome.

LEVEL OF EVIDENCE

Therapeutic level 4.

Retrograde lag screw placement in anterior acetabular column with regard to the anterior pelvic plane and midsagittal plane -- virtual mapping of 260 three-dimensional hemipelvises for quantitative anatomic analysis

Percutaneous screw placement can be used for minimally invasive treatment of none or minimally displaced fractures of the anterior column. The complex pelvic geometry can pose a major challenge even for experienced surgeons. The present study examined the preformed bone stock of the anterior column in 260 hemipelvises (130 male and 130 female). Screws were virtually implanted using iPlan(®) CMF (BrainLAB AG, Feldkirchen, Germany); the maximal implant length and the maximal implant diameter were assessed. The study showed, that 6.5mm can generally be used in men; in women however individual planning is essential in regard to the maximal implant diameter since we found that in 15.4% of women, screws with a diameter less than 6.5mm were necessary. The virtual analysis of the preformed bone stock corridor of the anterior column showed two constrictions of crucial clinical importance. These can be found after 18% and 55% (men) respectively 16% and 55% (women) measured from the entry point along the axis of the implant. The entry point of the retrograde anterior column screw in our collective was located lateral of tuberculum pubicum at the level of the superior-medial margin of foramen obturatum. In female patients, the entry point was located significantly more lateral of symphysis and closer to the cranial margin of ramus superior ossis pubis. The mean angle between the screw trajectory and the anterior pelvic plane in sagittal section was 31.6 ± 5.5°, the mean angle between the screw trajectory and the midsagittal plane in axial section was 55.9 ± 4.6° and the mean angle between the screw trajectory and the midsagittal plane in coronal section was 42.1 ± 3.9° with no significant deviation between both sexes. The individual angles formed by the screw trajectory and the anterior pelvic and midsagittal plane are independent from anthropometric parameters sex, age, body length and weight. Therefore, they can be used for orientation in lag screw placement keeping in mind that the entry point differs in both sexes.

Anatomical study of anterior column screw tunnels through virtual three-dimensional models of the pelvis

We created 66 male and 74 female virtual three-dimensional models of the pelvis based on computed tomography data from 140 patients. Virtual cylindrical bolts (VCBs) were placed in the anterior column (AC), which was then resliced serially along the bolt's long axis. AC screw tunnel mainly comprises two long, narrow triangular prisms [zone III (acetabular fossa) and zone V (obturator foramen)]--forming the III/V angle--linked by a larger, shorter cylinder [zone IV (acetabular notch)]. VCBs' mean length and maximum diameter were 111.13 ± 7.33 and 7.37 ± 1.90 mm, respectively. The models' anatomical zone lengths were similar between the sexes. Zone V's narrowest diameters and the III/V angles were significantly different. VCBs >6.5 mm were accommodated in 65 of 66 male models and 31 of 74 female models. VCBs >5.0 and <6.5 mm were accommodated in one male and 30 female models. Eleven female models accommodated only VCBs >3.5 and <5.0 mm. However, to 13 female pelvic models with maximum VCB accommodation of <5 mm for the anterior column, the maximum diameter of the VCBs was 8.23 ± 1.22 mm in medial passage and 10.3 ± 1.91 mm in lateral passage, respectively. Percutaneous fixation of the AC with screws is a safe technique, even though in Chinese female patients. The narrowest diameters in zone V and the III/V angles are the key factors for application of AC screws. Female patients with a smaller interosseous space at zone V and a large III/V angle can accommodate segmental passage screws.

Clinical applications of SPECT/CT in imaging the extremities

Today, SPECT/CT is increasingly used and available in the majority of larger nuclear medicine departments. Several applications of SPECT/CT as a supplement to or replacement for traditional conventional bone scintigraphy have been established in recent years. SPECT/CT of the upper and lower extremities is valuable in many conditions with abnormal bone turnover due to trauma, inflammation, infection, degeneration or tumour. SPECT/CT is often used in patients if conventional radiographs are insufficient, if MR image quality is impaired due to metal implants or in patients with contraindications to MR. In complex joints such as those in the foot and wrist, SPECT/CT provides exact anatomical correlation of pathological uptake. In many cases SPECT increases the sensitivity and CT the specificity of the study, increasing confidence in the final diagnosis compared to planar images alone. The CT protocol should be adapted to the clinical question and may vary from very low-dose (e.g. attenuation correction only), to low-dose for anatomical correlation, to normal-dose protocols enabling precise anatomical resolution. The aim of this review is to give an overview of SPECT/CT imaging of the extremities with a focus on the hand and wrist, knee and foot, and for evaluation of patients after joint arthroplasty.

The study of broken quadrilateral surface in fractures of the acetabulum

PURPOSE

Three-dimensional computerised tomography (3DCT) can provide comprehensive patho-anatomy of complex bone on a single image. Though important, the key articular quadrilateral [Q] surface has not been a part of the systems developed for classifying acetabulum fractures. The purpose of the study was to simplify the complexity of classification by the direct sign of the broken Q surface which lies opposite the entire floor of the acetabulum.

METHODS

The study reviewed 84 acetabular fractures using 3DCT images of the interior lateral view (IL) taken between June 2002 to December 2009. Fractures were traditionally classified using the anatomical disruption, plane of the fracture line breaking through or not through the bone column described by Judet and Letournel.

RESULTS

The 3D images clearly show the primary site of impaction acting on the acetabulum and the whole course of fracture. The image could not illustrate disruption of the lips of acetabulum and congruity of hip joints in 20 cases of wall (W) fracture. There were 30 transverse (T) fractures classified when the acetabulum was divided horizontally from front to back into upper and lower parts and 34 cases of column (C) fracture when the main vertical lines run and collide along the anterior and posterior column.

CONCLUSIONS

This study showed that the well-known complex fractures can be satisfactorily classified with the broad flat inner plane of the Q surface.