Exploring Fracture Patterns: Assessing Representation Methods for Bone Fracture Simulation

Fracture pattern acquisition and representation in human bones play a crucial role in medical simulation, diagnostics, and treatment planning. This article presents a comprehensive review of methodologies employed in acquiring and representing bone fracture patterns. Several techniques, including segmentation algorithms, curvature analysis, and deep learning-based approaches, are reviewed to determine their effectiveness in accurately identifying fracture zones. Additionally, diverse methods for representing fracture patterns are evaluated. The challenges inherent in detecting accurate fracture zones from medical images, the complexities arising from multifragmentary fractures, and the need to automate fracture reduction processes are elucidated. A detailed analysis of the suitability of each representation method for specific medical applications, such as simulation systems, surgical interventions, and educational purposes, is provided. The study explores insights from a broad spectrum of research articles, encompassing diverse methodologies and perspectives. This review elucidates potential directions for future research and contributes to advancements in comprehending the acquisition and representation of fracture patterns in human bone.

Mechanical Performance of Extensive Restorations Made with Short Fiber-Reinforced Composites without Coverage: A Systematic Review of In Vitro Studies

In recent years, composite resin materials have been the most frequently used materials for direct restorations of posterior teeth. These materials have some clinically relevant limitations due to their lack of fracture toughness, especially when used in larger cavities with high volume factors or when utilized as direct or indirect overlays or crown restorations. Recently, short-fiber-reinforced composite materials have been used in bi-structure restorations as a dentine substituting material due to their superior mechanical properties; however, there is no scientific consensus as to whether they can be used as full restorations. The aim of our review was to examine the available literature and gather scientific evidence on this matter. Two independent authors performed a thorough literature search using PubMed and ScienceDirect up until December 2023. This study followed the PRISMA guidelines, and the risk of bias was assessed using the QUIN tool. The authors selected in vitro studies that used short-fiber-reinforced composite materials as complete restorations, with a conventional composite material as a comparison group. Out of 2079 potentially relevant articles, 16 met our inclusion criteria. All of the included studies reported that the usage of short-fiber-reinforced composites improved the restoration's load-bearing capacity. Fifteen of the included publications examined the fracture pattern, and thirteen of them reported a more favorable fracture outcome for the short-fiber-reinforced group. Only one article reported a more favorable fracture pattern for the control group; however, the difference between groups was not significant. Within the limitations of this review, the evidence suggests that short-fiber-reinforced composites can be used effectively as complete restorations to reinforce structurally compromised teeth.

Fracture resistance and failure pattern of endodontically treated maxillary premolars restored with transfixed glass fiber post: an in vitro and finite element analysis

The aims of the study were to determine the effect of different types of endodontic sealers and the presence of a horizontal glass fiber post (HGFP) on the fracture resistance and fracture pattern of mesio-occluso-distal (MOD) restored upper premolars and to analyze the stress distribution. Sixty extracted upper premolars received root canal treatment (RCT) and a MOD cavity preparation. All MOD cavities were restored with the same composite resin (CR). The 60 teeth were divided randomly into 6 groups (n = 10); Group1= AH Plus sealer; Group 2= TotalFill BC sealer; Group 3= BioRoot RCS sealer; Group 4= AH plus sealer + HGFP; Group 5= TotalFill BC sealer + HGFP; and, Group 6= Bio Root RCS sealer + HGFP. All specimens were thermocycled and subjected to cyclic loading. Next, the specimens were subjected to a static load using a universal testing machine. Data were analyzed using two-way ANOVA. Two micro-CTs of the same upper premolar, one without the HGFP and later one with HGFP inserted were made and used to create two finite element (FE) models. For the fracture resistance, two-way ANOVA revealed significant differences for the effect of HGFP (p = 0.029), but no differences for the effect of root canal sealer type (p = 0.561). The HGFP groups showed higher restorable fracture compared to groups without HGFP (p = 0.013). Finite element analysis showed that the inclusion of HGFP reduces stress concentration at the occlusal interface and cervical region. Therefore, it can be concluded that HGFP significantly increased the fracture resistance of endodontically treated upper premolars with MOD cavities and reduced the risk for non-restorable fractures. The FE analysis supports the mechanical test results.

Effects of screw channel angulation on the fracture resistance of one-piece zirconia crown with titanium base

PURPOSE

The design of the angulated screw channel in implant restorations allows the possibility to correct angulation discrepancies, especially in the anterior maxilla. However, the effects of varied screw channel angulations on fracture resistances and fracture patterns of the implant restorations are still uncertain, and thus the aim of this study.

MATERIALS AND METHODS

Angulated screw channel monolithic zirconia crowns (Nobel Biocare) with three different angulation groups-straight (ASC1), 15° (ASC15), and 25° (ASC25)-were digitally designed from a left central incisor prototype scan. Following fabrication, 10 samples of each group were individually mounted onto implant replicas embedded in standardized type V stone gypsum cylinder jigs (25 mm × 25 mm). All screws were manually torqued to 35 Ncm according to the manufacturer's recommendation, and screw access openings were subsequently sealed with resin composite. To mimic the off-axis loading of the central incisor, the specimens were then loaded at a cephalometric interincisal relationship of 135° between the long axis of the crown and the Instron force applicator, with crosshead speed set at 0.5 mm/min. Fractured abutment surfaces were examined, and selected specimens were further evaluated by scanning electron microscopy. Screw torque values were also measured after the catastrophic loading. One-way ANOVA was used to compare load-to-fracture values between groups, with the statistical significance set at 0.05 (p values).

RESULTS

The mean load-to-fracture values in descending order were 331.24N (±34.00N) in ASC15, 325.22N (±35.50N) in ASC25, and 302.04N (±45.10N) in ASC1, with no statistically significant differences between groups. Considerable screw torque losses were found in all groups after catastrophically loading. The average torque loss was 84% in ASC1, 86% in ASC15, and 94% in ASC25. 16 out of 30 specimens experienced screw loosening; one ASC1 screw underwent slight deformation. Crowns of all tested groups exhibited cohesive fracture patterns at the screw-metallic-zirconia interfaces.

CONCLUSIONS

Within the limitations of this in vitro study, one-piece monolithic zirconia implant crowns with varied screw channel angulations shared similar fracture-strength and fracture-mode characteristics. The zirconia-titanium base junctions exhibited the weakest link of all restorations.

Is radiological rotation measurement affected by the fracture pattern in pediatric supracondylar humeral fractures?

BACKGROUND

In supracondylar humerus fractures (SCHF), the most frequently used method to calculate rotation is the Gordon lateral rotation percentage (GLRP) defined by Gordon et al. However, this technique includes only typical fractures (49%-80% of all fractures) from the Johns Hopkins (J-H) fracture classification system.

PURPOSE

The aim of the study was to investigate (1) is Gordon criteria useful for John Hopkins subgroups of supracondylar fractures and (2) is Gordon criteria affected by internal and external rotation.

MATERIAL AND METHODS

This study was designed using four pediatric left humerus bones obtained from the Sawbone© company. For each bone, an osteotomy was made to mimic each of the J-H coronal fracture patterns. The cut bones were placed in a wooden rotation apparatus. The GLRP measurements were taken by five blinded observers.

RESULTS

In the repeated measurements of the observers, <20° rotation typical and <30° medial oblique and lateral oblique fracture pattern were measured as within the limits of an acceptable amount of rotation according to the Gordon criteria. However, for high fracture pattern (HFP), ≤30° internal rotation and <60° external rotation were determined to be within the acceptable rotation criteria according to the Gordon criteria.

CONCLUSIONS

All fracture patterns have different characteristics; however, based on the data of this study, the Gordon criteria can be used safely for typical, medial oblique, and lateral oblique fracture patterns but it is necessary to lower the acceptable rate of 50% for HFP.

The influence of horizontal glass fiber posts on fracture strength and fracture pattern of endodontically treated teeth: A systematic review and meta-analysis of in vitro studies

PURPOSE

This systematic review and meta-analysis aimed to summarize available evidence regarding the effect of horizontal glass fiber posts (HGFPs) on fracture strength and fracture pattern of endodontically treated teeth (ETT) compared to controls without HGFP. The review protocol was registered on the OSF registries.

METHODS

Literature searches were conducted in MEDLINE/PubMed, Scopus, Web of Science, Embase, Google Scholar, and ProQuest for all relevant studies published up to February 2022. All in vitro studies that assessed the influence of HGFPs on fracture strength and fracture pattern of ETT whether mesio-occluso-distal or mesio-occlusal or DO cavities were considered eligible. Review Manager (RevMan) was used for the meta-analysis. Subgroup and funnel plot analyses were also performed. Quality assessment was conducted by two independent reviewers.

RESULTS

A total of 12 articles met the inclusion criteria, and 10 studies underwent quantitative evaluation. The pooled effect showed that fracture resistance of molar teeth restored with HGFP was significantly higher than teeth without HGFP (standardized mean difference [SMD]: 1.61, 95% confidence interval [CI]: 0.14, 3.09, p = 0.03), whereas marginally significant for premolars (SMD: 1.36, 95% CI: -0.00, 2.73, p = 0.05). Regarding fracture patterns, the presence of an HGFP significantly increased the occurrence of restorable fracture patterns for premolars (odds ratios [OR]: 4.15, 95% CI: 1.60, 10.82, p = 0.004) compared to controls, whereas the difference was not significant for molars (OR: 1.09, 95% CI: 0.43, 2.77, p = 0.85). Moderate risk of bias was identified in 9/12 studies; one study showed a high risk of bias and two studies showed a low risk of bias.

CONCLUSIONS

Within the limitations of this study, there is evidence from in vitro studies that the use of HGFP increases the fracture resistance of the ETT when compared to teeth without HGFP and also reduces the occurrence of non-restorable fractures for premolars. However, well-conducted in vitro and prospective clinical studies are warranted to validate this finding.

How Does Mechanism of Injury Relate to Similar Fracture Patterns in Bilateral Displaced Intra-articular Calcaneal Fractures?

Several biomechanical/cadaver studies have established a correlation between mechanism of injury and fracture classification in calcaneal fractures. However, this has never been backed up by clinical studies. In this study, the hypothesis is tested whether the alleged similar mechanism of injury for both feet in bilateral calcaneal fractures leads to similar fracture types. In this retrospective cross-sectional cohort study, patients with unilateral and bilateral calcaneal fractures treated between 2000 and 2017 were classified according to Essex-Lopresti and Sanders. Positive predictive values were computed, signifying the chance that the fracture type in the left foot corresponded to that in the right foot. These were compared to the a priori chance of a fracture type (percentage of fracture type in unilateral fractures) by constructing 95% confidence intervals of the positive predictive value of each fracture type. Of the 451 patients, 413 (91.6%) had unilateral and 38 (8.4%) bilateral calcaneal fractures. Mechanisms of injury were similar for uni- and bilateral fractures. Using the Essex-Lopresti fracture classification, 34 cases (90%) had the same classification in both feet, compared with 24 (63%) in the Sanders classification. The chance of a fracture type in the left, with the right foot as reference, was significantly larger than expected from a priori chance in the unilateral population. This leads to a new hypothesis, that, more than mechanism of injury, the magnitude of the impact and the position of the foot are important in predicting fracture classification in the calcaneus.

Proximal humeral fracture morphology in patients with advanced osteoarthritis: An observational study in a surgically treated cohort

BACKGROUND

Several factors affect proximal humeral fracture (PHF) morphology. In the presence of glenohumeral osteoarthritis (GOA), the joint kinematics is alternated which might influence fracture configuration. The purpose of this study was to identify fracture patterns in patients with advanced osteoarthritis to facilitate recognition and treatment.

METHODS

In this retrospective analysis, and computed tomography (CT) scans of all patients undergoing surgical treatment for a PHF during a 5-year period were analyzed. Fracture pattern according to the AO Foundation/Orthopaedic Trauma Association (AO-OTA) classification and the presence of GOA were evaluated. In addition, critical shoulder angle (CSA), glenoid configuration, and glenoid inclination (GI) were measured.

RESULTS

Of the 713 patients, 574 met the inclusion criteria. A total of 166 patients showed radiological signs of GOA (28.9%). Advanced GOA (stage 2 or 3) was identified in 23 patients (4.0%). In this group, the mean age was 77 ± 10 years, mean CSA was 28.8 ± 4.2°, and the mean GI was 19.0 ± 7.8°. All fractures were extra-articular metaphyseal fractures (5 A2, 11 A3, 7 B1.1). Patients with advanced GOA had more than threefold risk (risk ratio 3.2; confidence interval 95% 2.80-3.74; p < 0.0001) for sustaining a metaphyseal fracture. In patients with GOA grade 1 compared to patients with no radiographic signs of GOA, this could not be observed.

CONCLUSION

Patients experiencing PHF with radiological signs of advanced GOA have a higher risk of sustaining a metaphyseal fracture compared to individuals with the absence of or mild GOA. To date, no classification system for PHFs takes preexisting osteoarthritis into account, although it might indicate a different treatment and therefore the recognition is crucial.

Fracture mapping of complex intra-articular calcaneal fractures

Background

Intra-articular calcaneal fracture remains challenging to manage. Computed tomography and fracture mapping are useful for the diagnosis and treatment of calcaneal fractures. The aim of the present study was to characterize calcaneal fracture patterns using fracture mapping.

Methods

Sixty-two calcaneal fractures were retrospectively included in the study. For each case, the fracture was simulated reduction manually. The fracture lines and zones of comminution were graphically superimposed onto an intact calcaneal template to identify fracture patterns. Major fracture lines and comminution were assessed by focusing on the posterior joint facet, medial wall, lateral wall, sustentaculum tali, and anterior process.

Results

The fracture lines were mostly concentrated on the area anterior to the posterior joint facet and extended medially. The longitudinal lines ran posteriorly from the angle of Gissane, and separated the sustentaculum tali and medial wall from the calcaneal tuberosity. In the lateral wall, the fracture lines extended posteriorly with some branches to the bottom of the calcaneus. No fracture lines passed through the sustentaculum tali. Fracture lines of the posterior tuberosity and anterior process were rare.

Conclusions

Calcaneal fracture lines follow characteristic patterns, which are closely related to the bone structure and fracture mechanism. These fracture patterns will aid clinicians choose surgical approach and fixations in the treatment of calcaneal fractures.

Fracture lines and comminution zones in OTA/AO type 23C3 distal radius fractures: The distal radius map

OBJECTIVE

This study was designed to define fracture lines and comminution zones in OTA/AO 23C3 distal radius fractures from axial computed tomography (CT) images that would influence surgical planning, development of new classifications, and possible implant designs.

METHODS

Thirty-four consecutive OTA/AO 23C3 fractures treated by a single surgeon between January 2014 and December 2014 were analyzed. For each fracture, maps of the fracture lines and zones of comminution were drawn. Each map was digitized and graphically superimposed to create a compilation of fracture lines and zones of comminution. Based on this compilation, major and minor fracture lines were identified and fracture patterns were defined.

RESULTS

All major fracture lines were distributed in the central region of the radius distal articular surface. There is a recurrent fracture pattern with a comminution zone including the scaphoid and lunate fossa; Lister's tubercle; and ulnar, volar, and radial zones.

CONCLUSION

It is important for the practicing surgeon to understand these four main fragments. Knowledge of this constant pattern should influence the development of new classifications and possible implant designs.

Evaluation of the lingual fracture patterns after bilateral sagittal split osteotomy according to Hunsuck/Epker modified by an additional inferior border osteotomy using a burr or ultrasonic device

This study was conducted to compare fracture patterns and operation times after sagittal split osteotomy (SSO) by Hunsuck/Epker approach, performed using a burr or ultrasonic device, with and without osteotomy modification. A total of 80 SSOs were performed in fresh human cadavers using a burr or ultrasonic device to investigate the influence of surgical instruments as well as an additional bone cut on the inferior border of the mandible in terms of lingual fracture patterns. The times required for osteotomy and sagittal split were measured, and postoperative cone beam computed tomography images of all splits were analyzed. Without an additional inferior osteotomy, preferred splits according to Hunsuck/Epker were achieved in 35% of cases (7/20) with the burr and 45% (9/20) with the ultrasonic instrument. The inferior modification resulted in a greater number of unwanted fracture patterns in both groups. There was no relationship between the split technique and the fracture pattern (P=0.7854). Statistically significant differences in osteotomy time were observed between burr osteotomy and modified burr osteotomy (P=0.006), as well as modified ultrasonic osteotomy (P<0.001), but not between burr and ultrasonic surgery both without the inferior cut (P=0.36). The bone cut on the inferior border did not improve split control, but rather increased the risk of unwanted fractures and extended the operation time.

ABO system is not associated with proximal femoral fracture pattern in Southern Italy

INTRODUCTION:

The mechanism that leads to a given fracture pattern is not understood. Heredity could act in this field through the ABO system. We investigated the relationship between ABO blood system and hip fracture pattern in a population from Southern Italy.

METHODS:

Hip fractures were identified through a registry evaluation of the activity of a level I Hospital, and subsequently classified in 'intracapsular' or 'extracapsular' according to their anatomical location. Information on these patients' ABO blood type was collected and compared with general population data from the report on blood donors of the Salerno division of Italian Blood Volunteers Association (AVIS).

RESULTS:

590 hip fractures were included (414 extracapsular, 176 intracapsular) and compared with 709 blood donors. Fractured patients presented a blood group A more often and blood group O less often than the AVIS population ( p A vs. non-A = 0.0033; p O vs. non-O = 0.0024). None of the ABO blood groups were associated with fracture pattern ( p O vs. non-O = 0.5858, p A vs. non-A = 0.409; p B vs. non-B = 0.253; p AB vs. non-AB = 0.212). The rhesus factor was not associated the fracture pattern ( p = 0.34).

CONCLUSIONS:

The ABO blood type could play a role as a risk factor for proximal femoral fractures, but in our population its relevance in influencing the fracture pattern is unclear.

An Assessment of the Skeletal Fracture Patterns Resulting from Fatal High (˃3 m) Free Falls

The injury patterns resulting from fatal high (˃3 m) free falls have previously been documented in clinical and medico-legal contexts; however, details relating specifically to the skeletal blunt force trauma (BFT) have been limited. This study aimed to augment what is known of the skeletal fracture patterns resulting from fatal high free falls. Skeletal trauma was analyzed from full-body postmortem computed tomography scans of 95 individuals who died following a high free fall. Fracture patterns were documented using the five general anatomical regions, axial and appendicular regions, and postcranial unilateral and bilateral regions. Patterns were analyzed in the context of the extrinsic and intrinsic variables that may influence fractures using multiple logistic regression. Fracture patterns involved all aspects of the skeleton, with 98.9% exhibiting polytrauma, and were influenced primarily by the height fallen, manner of death, and landing surface. This improved understanding of fracture patterns will augment anthropological interpretations of the mechanism of BFT in cases of suspected high falls.

Facial Fracture Patterns Associated with Traumatic Optic Neuropathy

Traumatic optic neuropathy (TON) is rare. The heterogeneity of injury patterns and patient condition on presentation makes diagnosis difficult. Fracture patterns associated with TON have never been evaluated. Retrospective review of 42 patients diagnosed with TON at the R. Adams Cowley Shock Trauma Center from May 1998 to August 2010 was performed. Thirty-three patients met criteria for study inclusion of fracture patterns. Additional variables measured included patient demographics and mechanism. Cluster analysis was used to form homogenous groups of patients based on different fracture patterns. Fracture frequency was analyzed by group and study population. Visual depiction of fracture patterns was created for each group. Cluster analysis of fracture patterns yielded five common "groups" or fracture patterns among the study population. Group 1 ( n  = 3, 9%) revealed contralateral lateral orbital wall (100%), zygoma (67%), and nasal bone (67%) fractures. Group 2 ( n  = 7, 21%) demonstrated fractures of the frontal bone (86%), nasal bones (71%), and ipsilateral orbital roof (57%). Group 3 ( n  = 14, 43%) involved fractures of the ipsilateral zygoma (100%), lateral orbital wall (29%), as well as frontal and nasal bones (21% each). Group 4 ( n  = 5, 15%) consisted of mid- and upper-face fractures; 100% fractured the ipsilateral orbital floor, medial and lateral walls, maxilla, and zygoma; 80% fractured the orbital roof and bilateral zygoma. Group 5 ( n  = 4, 12%) was characterized by fractures of the ipsilateral orbital floor, medial and lateral orbital walls (75% each), and orbital roof (50%). A notably high 15 of 33 patients (45%) sustained penetrating trauma. Our study demonstrates five fracture pattern groups associated with TON. Zygomatic, frontal, nasal, and orbital fractures were the most common. Fractures with a combination of frontal, nasal, and orbital fractures are particularly concerning and warrant close attention to the eye.

Evaluation of Fibular Fracture Type vs Location of Tibial Fixation of Pilon Fractures

BACKGROUND

Comminuted fibular fractures can occur with pilon fractures as a result of valgus stress. Transverse fibular fractures can occur with varus deformation. No definitive guide for determining the proper location of tibial fixation exists. The purpose of this study was to identify optimal plate location for fixation of pilon fractures based on the orientation of the fibular fracture.

METHODS

One hundred two patients with 103 pilon fractures were identified who were definitively treated at our institution from 2004 to 2013. Pilon fractures were classified using the AO/OTA classification and included 43-A through 43-C fractures. Inclusion criteria were age of at least 18 years, associated fibular fracture, and definitive tibial plating. Patients were grouped based on the fibular component fracture type (comminuted vs transverse), and the location of plate fixation (medial vs lateral) was noted. Radiographic outcomes were assessed for mechanical failures.

RESULTS

Forty fractures were a result of varus force as evidenced by transverse fracture of the fibula and 63 were due to valgus force with a comminuted fibula. For the transverse fibula group, 14.3% mechanical complications were noted for medially placed plate vs 80% for lateral plating ( P = .006). For the comminuted fibular group, 36.4% of medially placed plates demonstrated mechanical complications vs 16.7% for laterally based plates ( P = .156). Time to weight bearing as tolerated was also noted to be significant between groups plated medially and laterally for the comminuted group ( P = .013).

CONCLUSIONS

Correctly assessing the fibular component for pilon fractures provides valuable information regarding deforming forces. To limit mechanical complications, tibial plates should be applied in such a way as to resist the original deforming forces. Level of Evidence Level III, comparative study.

Three-dimensional fracture pattern analysis of the Obwegeser and Dal Pont bilateral sagittal split osteotomy

The Obwegeser and Dal Pont modification of the bilateral sagittal split osteotomy (BSSO) is a well-established procedure in orthognathic surgery. The purpose of this retrospective study was to analyze the actual fracture patterns achieved with BSSO by Obwegeser and Dal Pont modification using postoperative cone beam computed tomography (CBCT) datasets from 100 patients. A total of 200 split osteotomies were assessed, which could be categorized into nine different split patterns. Only one of the observed split fractures (0.5%) followed exactly the fracture line described by Obwegeser and Dal Pont, whereas 40% followed the fracture line according to the Hunsuck and Epker modification and 13.5% were seen as unfavourable splits mainly running over the buccal plate. A significant correlation was found between unfavourable buccal splits and both horizontal osteotomies reaching the buccal surface at the dorsal ramus (P=0.001) and a vertical caudal bone cut end at the corpus with a buccal position (P<0.001). These results show that a complete antero-posterior horizontal osteotomy at the mandibular ramus does not lead to the intended fracture pattern, which rebuts the argument of a greater amount of bony overlap using the Obwegeser and Dal Pont modification.

Effect of Curing Mode on Shear Bond Strength of Self-Adhesive Cement to Composite Blocks

To overcome the disadvantages of computer-aided design/computer-aided manufacturing (CAD/CAM) processed indirect restorations using glass-ceramics and other ceramics, resin nano ceramic, which has high strength and wear resistance with improved polish retention and optical properties, was introduced. The purpose of this study was to evaluate the shear bond strength and fracture pattern of indirect CAD/CAM composite blocks cemented with two self-etch adhesive cements with different curing modes. Sand-blasted CAD/CAM composite blocks were cemented using conventional resin cement, Rely X Ultimate Clicker (RXC, 3M ESPE, St. Paul, MN, USA) with Single Bond Universal (SB, 3M ESPE, St. Paul, MN, USA) for the control group or two self-adhesive resin cements: Rely X U200 (RXU, 3M ESPE, St. Paul, MN, USA) and G-CEM Cerasmart (GC, GC corporation, Tokyo, Japan). RXU and GC groups included different curing modes (light-curing (L) and auto-curing (A)). Shear bond strength (SBS) analyses were performed on all the specimens. The RXC group revealed the highest SBS and the GC A group revealed the lowest SBS. According to Tukey's post hoc test, the RXC group showed a significant difference compared to the GC A group (p < 0.05). For the curing mode, RXU A and RXU L did not show any significant difference between groups and GC A and GC L did not show any significant difference either. Most of the groups except RXC and RXU L revealed adhesive failure patterns predominantly. The RXC group showed a predominant cohesive failure pattern in their CAD/CAM composite, Lava^TM Ultimate (LU, 3M ESPE, St. Paul, MN, USA). Within the limitations of this study, no significant difference was found regarding curing modes but more mixed fracture patterns were showed when using the light-curing mode than when using the self-curing mode.

Applied anatomy of the anterior cranial fossa: what can fracture patterns tell us?

The skull base is uniquely placed to absorb anteriorly directed forces imparted either via the midfacial skeleton or cranial vault. A variety of skull base fracture classifications exist. Less well understood, however, is fracture extension beyond the anterior cranial fossa (ACF) into the middle and posterior cranial fossae. The cases of 81 patients from two UK major trauma centres were studied to examine the distribution of fractures across the skull base and any relationship between the vector of force and extent of skull base injury. It was found that predominantly lateral force to the craniofacial skeleton produced a fracture that propagated beyond the ACF into the middle cranial fossa in 77.4% of cases, significantly more (P<0.001) than for predominantly anterior force (12.0%). Fractures were significantly more likely to propagate into the posterior fossa with a lateral vector of impact compared to an anterior vector (P=0.049). This difference in energy transfer across the skull base may, in part, be explained by the local anatomy. The more delicate central ACF acts as a 'crumple zone' in order to absorb force. Conversely, no collapsible interface exists in the lateral aspect of the ACF, thus the lateral ACF behaves like a 'buttress', resulting in increased energy transfer.

Association of ABO blood group with fracture pattern and mortality in hip fracture patients

INTRODUCTION

The mechanism of falling has been proposed as the exclusive explanation for hip fracture pattern. Evidence exists that other genetic factors also influence proximal femoral fracture configuration. The ABO blood group serotype has been associated with other pathologies but any role in hip fracture has yet to be definitively characterised.

METHODS

Our National Hip Fracture Database was interrogated over a four-year period. All patients had their blood group retrieved, and this was compared with hip fracture pattern and mortality rates. Confounding factors were accounted for using logistic regression and the Cox proportional hazards model.

RESULTS

A total of 2,987 consecutive patients presented to our institution. Those with blood group A were significantly more likely to sustain intracapsular fractures than 'non-A' individuals (p=0.009). The blood group distribution of patients with intracapsular fractures was identical to that of the national population of England. However, blood group A was less common in patients with intertrochanteric fractures than in the general population (p=0.0002). Even after correction for age and sex, blood group A was associated with a decrease in the odds of suffering an intertrochanteric fracture to 80% (p=0.002). Blood group A had inferior survivorship correcting for age, sex and hip fracture pattern (hazard ratio: 1.14, p=0.035). This may be due to associated increased prevalence of co-morbid disease in this cohort.

CONCLUSIONS

Blood group is an independent predictor of hip fracture pattern, with group A patients more likely to sustain an intracapsular fracture and non-A individuals more likely to sustain an intertrochanteric fracture. The determinants of fracture pattern are likely to be related to complex interactions at a molecular level based on genetic susceptibility. The mechanism of fall may not be the only aetiological determinant of proximal femoral fracture configuration.