Transverse Fracture Research Articles

Bowland Shale well placement strategy – Part 2: Fracture simulations using a 3D geomechanical model and implications for stratigraphic and spatial horizontal well locations

Hydraulic fracture modelling is a key component of a shale reservoir well placement strategy as it provides an indication of the typical lengths and heights of stimulated fractures and of the changes to the stress environment in which these are propagating. However, spatial and stratigraphic variations in the stress and geomechanical properties of shales make accurate modelling a challenging task. For the UK Bowland Shale, stacked horizontal wells targeting multiple stratigraphic intervals could be used to avoid large offset faults in a geologically complex area. However, it is not known how these intervals may respond to hydraulic fracturing and predicting the height and length of hydraulic fractures is necessary in order to assess the likelihood of vertical fracture interference across landing zones or propagation towards major faults. In the case of the former, intervals of high effective stress may be key to containing fractures within their desired target. Using a planar hydraulic fracture simulator, and a 3D geomechanical model incorporating dipping stratigraphy, the issue of predicting hydraulic fracture geometry in the Bowland Shale was assessed through a series of modelling exercises using well Preese Hall-1 and horizontal pseudo-wells. When pre-defined landing zones were targeted, narrow and long transverse fractures around 1 km from the well were simulated. When the simulation design mimicked perforation clusters placed at 12 m intervals along horizontal pseudo-wells, the effects of stress shadowing were acute and resulted in irregular fracture geometries. Furthermore, high effective stress intervals performed efficiently as barriers to vertical hydraulic fracture propagation, reinforcing the feasibility of using stacked production for the Bowland Shale. The modelling results were then used to discuss the possible placement of horizontal wells in a mapped, 100 km2 region around well Preese Hall-1, where up to 13 sites could be positioned, with a horizontal well length of around 1.5 km. Finally, by drawing on a well-established analogue for the Bowland Shale, it was estimated that up to 195 Bcf of gas could be produced from the 13 locations in the area if three stratigraphic intervals are produced from one location.

Clinical Study of Surgical Management of Olecranon Fracture

Background and Objective When displaced ,Open reduction and internal fixation with k-wires and figure of eight tension band wiring for simple transverse fractures and olecranon hook plate for comminuted fractures The present study is undertaken to evaluate the results of surgical management, the merits and demerits and to asses elbow joint motion and stability after the procedure. Materials and Methods It is a prospective study which was carried out from September 2010 to September 2012 in Bapuji Hospital and Chigateri General Hospital attached to J.J.M Medical College, Davangere. In this study period of 25 cases of fracture olecranon treated by Tension band wiring with Kirshner wire for Simple transverse fractures and Olecranon hook plate for Communited fractures Results In our series, majority of the patients were males, middle aged, with road traffic accident being the commonest mode of injury, Most of the cases were Type II B fractures i.e., oblique and transverse fractures according to Colton’s classification Surgery was performed with in 3.48 average days, Union was noted clinically and radiologically and functional evaluation was done by Mayo elbow performance score. Excellent results was present in 18 patients (72%), 4(16%) good and 3(12%) fair with no poor results. Interpretation / Conclusion From the present study it is concluded that the technique of open reduction and internal fixation with Kirschner wires and tension band wiring for simple transverse and oblique fractures and olecranon plate fixation for comminuted fractures are effective means and gold standard technique of treating fractures of olecranon and is based on sound biomechanical principle.

Experimental Investigation of the Growth Law of Multi-Fracture during Temporary Plugging Fracturing within a Stage of Multi-Cluster in a Horizontal Well

Temporary plugging fracturing in a horizontal well with multi-stages and multi-clusters is usually used to improve stimulation efficiency and increase the gas production from shale gas reservoirs. However, the fracture propagation geometry and the mechanism of temporary plugging are still unclear, which restricts the further optimization of temporary plugging fracturing scheme. In this study, taking the Longmaxi shale as the research object and considering the intrafracture and intrastage temporary plugging, the true tri-axial hydraulic fracturing system was used to put forward an experimental method for simulating the temporary plugging fracturing in a horizontal well with multi-stages and multi-clusters. Afterward, the effects of the size combination and concentration of temporary plugging agents and the cluster number in a stage on the fracture geometry created in the secondary fracturing were investigated in detail. The results show that an optimal fracture propagation geometry tends to be obtained by using the combinations of 100 to 20/70 mesh, and 20/70 to 10~18 mesh temporary plugging agents for the intrafracture and intrastage temporary plugging, respectively. Increasing the proportion of the temporary plugging agent of a larger particle size can improve the effectiveness of intrafracture and intrastage temporary plugging fracturing, and tends to open new fractures. With the increase in temporary plugging agent concentration and the cluster number within a stage, both the number of diverting fractures formed and the overall complexity of fractures tend to increase. After fracturing, the rock specimen with a high peak in the temporary plugging pressure curve has more transverse fractures, indicating a desirable diversion effect. By contrast, the fractured rock specimen with a low peak pressure has no transverse fracture, generally with fewer fractures and poor diversion effect.

Fast-running model for high-volume hydraulic fracturing

We develop a rapid simulator of hydraulic fracture growth in complex geologic layered conditions and extensively drilled multistage fractured wells in a reservoir. The simulator allows running independent simulations for thousands hydraulic fractures within a minute on modern personal computers. The model is meshless and has a simplified rectangular fracture shape; however, coupling all conventional hydraulic fracture mechanics equations makes the model accurate enough. We demonstrate it via comparison with exact analytical solutions in limiting toughness-, viscosity-, and leakoff-dominated regimes, as well as via comparison with other commercial simulators on real field cases. Field validation of the model by temperature log measurements is also provided.To demonstrate the practical implications of the model for reservoir engineering, we show several examples of numerical simulations for a huge number of hydraulic fractures in a reservoir, which interact with each other due to the closeness of stimulated wells and perforation clusters. Rapid simulations allow obtaining the field-scale simulations of fracture growth in the range of a minute and efficiently building distributions of asymmetric fracture growth both in length and in height. We show that the stress shadow effect causes undesired outbreaks to adjacent gas- or water-saturated geological layers if the fracture placement in a reservoir is dense enough. Even small spatial misalignment of stages in the offset wells may result in changes of geometry of transverse fractures growing from neighbored wells. Vertical true vertical depths mismatch in offset wells; their deviations in the dip and azimuth angles are shown to cause the asymmetry of fracture growth as well, which hardly can be predicted in field development workflows without rigorous fracture simulations. Examples of longitudinal fracturing in horizontal wells demonstrate the strongest distortion of conventionally assumed lateral symmetry and height growth similarity of fractures created in one horizontal well. Our simulations also show that these results are affected by the viscosity of pumped fracturing fluids. The presented model of field-scale interactive fracture growth in a reservoir enables finding the best fracture placement characteristics and pumping schedule for the needs of field development with hundreds to thousands of fractures in a short time frame.

Medical management and rehabilitation in posttraumatic common peroneal nerve palsy

Introduction. The common peroneal nerve and the tibial nerve are the two major components into which the sciatic nerve divides. The severity of common peroneal nerve damage depends on the aetiopathogenic mechanism and the place of injury. The peroneal ram of the sciatic nerve injury is the most common cause of mononeuropathy of the lower limb which can cause a signi-ficant disability if is not properly diagnosed and treated. Material and method. We present the case of a 40-year-old patient who suffered a polytrauma by road accident resulting in left tro-chanteric-diaphyseal femoral comminuted open fracture, lacerated wound on the posterolateral middle third of the left thigh, left sacral wing fracture without displacement, left L1, L2, L3 tran-sverse apophyseal fractures and splenic laceration, treated surgically and orthopedically. The pa-tient was admitted to the Medical Reabilitation Department of Sibiu for left leg motor deficit, mechanical pain and functional deficit of the left hip and ankle, gait disorders. Complex rehabi-litation treatment was initiated 3 months after the accident. Results and discussion. Common pe-roneal nerve palsy was confirmed following neurological consultation the day after admission to Orthopaedics-Traumatology Department of Sibiu where continuous extension-traction was performed in order to relax the fracture and subsequent osteosynthesis surgery of the femur fracture. The presence of a deep and lacerating wound on the posterolateral left thigh caused the nerve injury. The coagulase-negative Staphylococcus aureus overinfection of the wound required secondary suturing and subsequently led to fibrous scar formation, adversely affecting the post-injury repair of the common fibular nerve. Conclusions. In patients with posttraumatic common peroneal nerve palsy, early diagnosis and appropriate treatment, including medical rehabilitation, are essential. Medical rehabilitation should be continued on a sustained basis be-cause nerve regeneration occurs slowly. The prognosis mainly depends on the severity of the initial nerve injury. Keywords: common fibular nerve injury, polytrauma, medical rehabilitation

A Porothermoelastic Model Considering the Dynamic Temperature-Perturbation Boundary Effect for Borehole Stability in Fractured Porous Rocks

Summary Conventional drilling design tends to inappropriately predict the mud density required for borehole stability of deep fractured porous rocks, such as shale, tight sandstone, and hot dry rock, because it is treated as a single-porosity case and even introduces the influence of weak plane to cover the effect on the fracture system. When the external loadings are applied, fractured porous rocks naturally display two different poromechanical responses of the matrix system and the fracture system considering respective hydraulic and mechanical properties. Besides, the constant temperature difference between the drilling mud and formation rock is often chosen as a boundary condition to solve the temperature balance equation, and thus the incorrect prediction of temperature variations of fractured rock further leads to inappropriate evaluation of the pore pressure and stress fields considering the thermo-hydromechanical (THM) coupling (porothermoelastic model), since a dynamic temperature-perturbation boundary condition related to the temperature at the borehole wall actually accounts for the circulating effect of the drilling mud. Therefore, this paper first uses the API RP 13D (1995) model in combination with the circulating temperature-fields model of Raymond (Raymond 1969) to obtain a set of fully transient analytical solutions to circulating temperature fields, including the four types of temperature inside the drilling pipe, borehole annulus, at the borehole wall, and formation. Furthermore, under local thermal equilibrium (LTE) condition, one considers the dynamic temperature-perturbation boundary condition and provides semianalytical porothermoelastic solutions to the field variables around a vertical borehole subjected to nonhydrostatic stresses in fractured porous rock with dual porosity and dual permeability. The solutions for field variables are obtained in line with the plane strain assumption. The variables include displacements, stresses, and two pore pressures of the matrix system and fracture system. The model is verified by the analytical solutions in the case of a porous medium with a single-porosity one under LTE condition. The main results show that the dual-porosity medium displays a higher borehole instability potential than the single-porosity one. This increasingly cooling effect increases the higher risk of the tensile transverse fracturing when the constant temperature-perturbation boundary condition chooses a smaller temperature difference than that of the dynamic case at a later time. The drilling mud-pressure window narrows with increasing time when the coupled porothermoelastic model is considered. It suggests that the drilling engineer takes into consideration the dynamic temperature-perturbation boundary effect, fracture spacing, and fracture width into the predrilling design of the time-dependent safe mud-pressure window (SMPW).

Surgical treatment of acetabular fracture

The kocher -Langenbeck approach is the best suited approach for reduction and fixation of acetabular fracture that require fixation through posterior approach and provides sufficient access to the majority of posterior based acetabular fracture. Accuracy of fracture reduction is the strongest predictor of clinical outcome in acetabular fixation surgery.Twenty four patients with posteriorly based acetabular fracture were treated with open reduction and internal fixation using Kocher- Langenbeck incision. In our series, there were 11 posterior wall, 3 posterior column, 5 transverse, 2 posterior column and posterior wall and 3 transverse and posterior wall fractures. All the patients were in the age group of 30 to 45 years (mean age 38.5 years). Males dominated our series (n=18 i.e. 75%) and right side was more commonly involved in both the sexes (n=14 i.e. 58.33%). Road traffic accident was the leading cause (n=19 i.e. 79.16%). All the patients were operated achieving adequate stability and with utmost soft tissue care. Follow up radiograph were graded according to criteria developed by Matta J et al. A minimum follow up was two years. Patient with accurate reconstruction (n =21 i.e. 87.50%) had good or excellent functional outcome while two patients (08.33%) with inaccurate reduction and one patient (04.16%) with poor reduction had fair and poor outcome respectively. Despite relatively large number of possible complications Kocher–Langenbeck Approach is the best suited approach for posterior acetabular fracture.

Experimental evaluation of fracture properties of bovine hip cortical bone using elastic-plastic fracture mechanics.

Understanding the fracture mechanics of bone is very important in both the medical and bioengineering field. Bone is a hierarchical natural composite material of nanoscale collagen fibers and inorganic material. This study investigates and presents the fracture toughness of bovine cortical bone by using elastic plastic fracture mechanics. The J-integral was used as a parameter to calculate the energies utilized in both elastic deformation (Jel) and plastic deformation (Jpl) of the hipbone fracture. Twenty four different types of specimens, i.e. longitudinal compact tension (CT) specimens, transverse CT specimens, and also rectangular unnotched specimens for tension in longitudinal and transverse orientation, were cut from the bovine hip bone of the middle diaphysis. All CT specimens were prepared according to the American Society for Testing and Materials (ASTM) E1820 standard and were tested at room temperature. The results showed that the average total J-integral in transverse CT fracture specimens is 26% greater than that of longitudinal CT fracture specimens. For longitudinal-fractured and transverse-fractured cortical specimens, the energy used in the elastic deformation was found to be 2.8-3 times less than the energy used in the plastic deformation. The findings indicate that the overall fracture toughness measured using the J-integral is significantly higher than the toughness calculated by the stress intensity factor. Therefore, J-integral should be employ to compute the fracture toughness of cortical bone.

Percutaneous minimally invasive treatment of transverse patellar fracture using cannulated screws combined with high-strength sutures and Nice knots: a retrospective study.

Patella fractures treated with traditional open approach and tension band fixation are associated with a significant rate of soft tissues complications, including hardware irritation, postoperative adhesions and non-cosmetic scar. An alternative is to utilize cannulated screws and high-strength sutures by the minimally invasive technique. This retrospective study comprised 48 patients who had been treated for unilateral closed transverse patellar fracture, type 34C1 according to the AO Foundation and Orthopaedic Trauma Association (AO/OTA) classification, between June 2018 to June 2020. All patients were treated either by closed reduction and internal fixation using cannulated screws combined with high-strength sutures and Nice knots (the CRIF-NK group, n=24), or traditional open reduction and internal fixation using cannulated screws and tension band wiring (the ORIF-TBW group, n=24). The operative time and intraoperative blood loss for each patient were recorded. All the patients were underwent a regularly clinical and radiological follow-up. The clinical evaluation was performed using the Böstman scale and the Visual Analogue Scale (VAS) for pain. Average follow up was 21.9 months (range, 16-29 months). The mean intraoperative blood loss of the CRIF-NK group (35.21±6.16 mL) was significantly less than that of the ORIF-TBW group (75.42±7.92 mL; P<0.001). The mean VAS scores at 4 and 8 weeks and the mean Böstman scale score at 8 weeks after surgery were significantly better in the CRIF-NK group (3.52±0.42, 1.47±0.40 and 28.13±0.94, respectively) than the ORIF-TBW group (5.16±0.68, 3.14±0.72 and 26.33±1.00, respectively; all P<0.001). No significant differences were observed between the two groups in terms of operative time, Böstman scale score at 1-year follow-up, or fracture healing time. The union rate was 100% (24/24) in both groups. One patient (1/24) in the CRIF-NK group, and all patients (24/24) in the ORIF-TBW group required internal fixation removal. The percutaneous minimally invasive technique using cannulated screws combined with high-strength sutures and Nice knots exhibited some superiority to traditional open reduction with cannulated screws and tension band wiring for treatment of transverse patellar fractures in terms of efficacy and safety by reducing soft-tissue stimulating complications and promoting functional recovery.

A PROSPECTIVE STUDY OF SURGICAL MANAGEMENT OF FRACTURES OF OLECRANON IN ADULTS BY VARIOUS MODALITIES.

Background: The fracture of the olecranon process of ulna is an intraarticular injury leading to loss of extensor meachanism of elbow and thus needs surgical management. There are various modalities of management of olecranon fracture in adults like TBW with K-wire or 6.5 mm cancellous screw or olecranon plate. The aim of the present study is to clinically evaluate and compare the results of above different xation methods. Methods: This study was conducted at tertiary care medical college and hospital,Aurangabad where 30 adult patients who underwent surgical treatment by various modalities between September 2019 to October 2021 were included. Patients were assessed using Mayo Elbow Performance Score .Patients were followed up on 1 st , 3rd and 6 th month postoperatively. Conclusion: Several options exists for the management of olecranon fracture.Present study recommends use of olecranon plate for comminuted fractures and TBW with cannulated screws or TBW with k -wire in cases of oblique and transverse fractures.

EVALUATION OF FUNCTIONAL OUTCOME OF MODIFIED TENSION BAND WIRING AT 6 MONTHS IN ISOLATED OLECRANON FRACTURES IN ADULTS

Introduction: Fractures of the olecranon account for 8 - 10 % of all fractures around the elbow joint . An uncomplicated fracture of the olecranon is considered to be a common injury. Incidence in adult population is approximately 11.5% per 1 64 100000 population .Younger individuals suffer fracture olecranon due to high energy trauma and older individuals due to simple fall . When displaced, open reduction and internal xation is usually required to obtain anatomical realignment of the articular surface and restore normal elbow function. The xation should be stable, allow active elbow exion and extension and promote union of the fracture. There are other modalities of xation of isolated olecranon fractures, such as olecranon hook plate and cannulated lag screws as well but tension band wiring is less costly and operative complications are less in non comminuted olecranon fractures. Material and methods: This prospective observational study was done over a period of 2 years on transverse and oblique fractures of olecranon. Results: the outcome of our study was favorable in support of tension band wiring in transverse and oblique fracture of olecranon in respect to union rate, early initiation of physiotherapy and nal range of motion. Conclusion: By this method post-operative immobilization in POP is greatly minimized. Thereby avoiding fracture disease.Because of rigid xation between the fracture fragments, early active and functional movements can be given to the patient reducing the chances of joint stiffness. Early initiation of physiotherapy program within 2 – 3 weeks induces compression between the fragments. This compression hastens fracture healing. Because of early union of fracture, patient is back to work earlier

Formulation of nanocellulosic fibres and particle fillers, and their mono and hybrid reinforced polymer composites

Finite element analysis was used to formulate novel models of both mono and hybrid nanocomposites, and, also to predict their flexural properties. This study also formulated the optimal combination mix ratio of fibres and matrix of the flexural properties for use in different applications. The predicted properties were verified using the experimental method. This study found that the flexural properties of all the composites depicted an increase with fibre additions up to a certain optimum point, beyond which they began to fall gradually with further fibre additions. There was also evidence of transverse matrix fracture in rice husk nanoparticle-reinforced epoxy resin composites’ flexural stiffness graphs. Moreover, it was found that the increases in flexural properties of mono composites were about two times lower in magnitude than hybrid composites. With regards to the formulation of optimal combination mix ratio of fibres and matrices for different applications, it was noted that the optimal combination mix ratio of fibres to the matrix for applications where all the flexural properties were maximized was 4:1. Moreover, the optimal combination mix ratio of fibres to the matrix for applications where the flexural properties were minimized was 1:2. Furthermore, the optimal combination mix ratio of fibres to the matrix for applications with a target of 10 MPa flexural strength properties and 10 GPa for flexural stiffness properties was 2:3.

Investigation of the transverse fracture mechanisms of bamboo by the finite element method

Investigation of the transverse fracture mechanisms of bamboo by the finite element method

Ankle Injuries.

Ankle Injuries.

Prospective Comparative Study of Fixing Displaced Transverse Patellar Fracture by Tension Band Wiring Versus Cannulated Screws with Wiring

BACKGROUND: Transverse fractures of the patella are important fractures with a wide variety of subtypes, the common incidence in the age group of 20–50 years. Surgical interference aims to achieve a perfect alignment of the joint surface, in addition to rigid fixation of the fracture for early re-habitation and early movement to retain the extensor mechanism of the knee joint. AIM: The aim of this study was to compare the radiological and functional outcomes of the displaced transverse patella fracture in adult patients treated by ORIF using tension band wiring versus cannulated screws with wiring. METHODS: A prospective analytic comparative study was conducted in Al-Kindy Teaching Hospital/Baghdad/Iraq for 18 months from April 1, 2019, to October 1, 2020. It included 32 patients with isolated displaced transverse patellar fracture AO type 34-C1. The patients have undergone operative fixation with two different surgical techniques divided randomly by choosing every other patient into two groups. Group A, the fracture was fixed by cannulated screws with wiring and Group B, the fracture was fixed by two K-wires and with tension band technique. Postoperatively, assessment of the knee function by Lysholm score, the visual analog scale for pain intensity, and active flexion range of movement were measured in degree as primary outcomes, while time to union in weeks assessed radiographically as secondary outcomes. RESULTS: The patients’ age was ranging from 26 to 49 years, with males predominant. Low-energy falls occupying a major part of the mechanism of injury in both groups. Lysholm score was significantly increased after 3, 6, and 12 months compared to that after 1 month in both groups with no statistical differences. The mean visual analog score significantly decreased in Group A after 1 month than that in Group B with no significant change in the other follow-up periods. There were no statistically significant differences in both groups regarding the range of knee movement and the radiographic assessment of fracture healing. CONCLUSION: Both techniques are good and effective with taking into consideration that open reduction and cannulated screws fixation with wiring technique is shown to be associated with lower post-operative pain and a lower frequency of complications mainly surgical site infection.

State of the Art : Current Acetabulum Fracture Management

The annual incidence of acetabulum fractures is estimated to be 8.1 per 100.000 patients. In young adults, high energy trauma is the primary mechanism, but in the elderly, low energy trauma is the primary mechanism. Comorbidities, poor bone quality, and delayed presentation are all linked to a poor outcome. From diagnosis to treatment, the goal of this study is to describe the required procedures in reaching a satisfactory result.It is essential to be able to correctly classify acetabular fractures using the Joudet and Letournel classifications, especially when planning definitive therapy. Non-surgical and operative treatment methods are available for acetabulum fractures. All acetabulum fractures that result in hip joint instability and/or incongruity require surgical treatment. Although the prognosis is lower than in younger patients, Open Reduction Internal Fixation (ORIF) remains the mainstay of therapy for most elderly acetabular fractures. Central fracture dislocation of the hip with medial migration of the quadrilateral plate is common in patients with both column, transverse, T-shaped, and anterior column-posterior hemi-transverse fractures. Failure to repair the quadrilateral plate will result in an incongruent hip and a poor outcome since it has a thin medial wall that fractures with less force than the superior weight-bearing portion of the acetabulum.The goals of postoperative care are to maximize the patient's function, allow a quick return to function, and detect early problems. Complications with acetabulum fractures might occur with any treatment option. Post-traumatic arthritis is the most common complications, followed by Deep Vein Thrombosis (DVT), heterotrphic ossification, infection, and iatrogenic sciatic nerve damage.

Surgical correction of a complete diaphyseal humeral fracture of Brahminy kite -a case report

A young Brahminy kite (Haliastur indus) weighing 600g was presented to the Shahedul Alam Quadary Teaching Veterinary Hospital, at Chattogram Veterinary and Animal Sciences University, with a history of trauma due to collision with electric wire, which was unable to fly. Physical examination revealed temperature106ºF, depressed bird with bluish discoloration of subcutaneous tissue from shoulder to elbow joint of right wing and radiographic examination showed complete transverse diaphyseal right humeral fracture. Retrograde intramedullary pinning was done under general anesthesia with diazepam and ketamine combination. Post-operative radiograph confirmed the implant was in position. The total anesthetic period of the surgery was 60 minutes. The present study suggests that, intramedullary pinning can be successfully used for humeral fracture management in kite with proper anesthetic protocol. Postoperative care is very important for a successful outcome in avian orthopedics.

Lumbo-sacral Junction Instability by Traumatic Sacral Fractures: Isler's Classification Revisited - A Narrative Review.

Study DesignNarrative reviewObjectivesMultiple classifications have been proposed for sacral fractures since the last century. While initial classifications focussed on vertical and transverse fractures, the recent fracture classifications encompass all injury patterns. In 1990, Isler classified unilateral vertical sacral fractures based on its potential influence on lumbo-sacral joint (LSJ) stability.MethodsWe re-visited the original description of Isler’s classification of sacral fractures and subsequent studies that have cited it. We will further describe basic LSJ anatomy, evolution of sacral classification systems and the use of Isler’s classification system as it relates to LSJ instability and chronic low back pain.ResultsIsler described a subset of unilateral vertical sacral fractures where the fracture line exited medial or through the L5-S1 facet joint, based on radiographic review of 193 sacral fractures (incidence -3.5%). He stated that such a fracture should be recognised as it can impede hemi-pelvis reduction and can result in late LSJ instability. The article has been cited in 106 studies and only a few studies have described the incidence of this variant. Nevertheless, the injury is considered as an indication for surgical fixation.ConclusionA review of various classifications indicates that sacral fractures have three important bio-mechanical implications, namely, pelvic ring continuity (vertical fractures), spino-pelvic alignment (high transverse fractures) and lumbo-sacral joint integrity (Isler’s fractures). Though there is a universal recognition of Isler’s fractures and its impact on LSJ integrity, there is a lack of clinical and bio-mechanical evidence regarding the concept of instability caused by a unilateral Isler fracture.

A cortical screw based tension band construct for transverse patella fractures: An evolving strategy for addressing common modes of failure

IntroductionDisplaced patella fractures represent a clinical challenge. We evaluate the effectiveness of an alternative fixation construct to address common modes of fixation failure. MethodsA retrospective review of 49 patients who underwent fixation via the specific construct at a single institution between 2013 and 2019. ResultsMedian follow-up was 52.7 weeks (Mean: 75.4 weeks; SD: 54.9; range: 27–267.7 weeks). Construct failure rate was 6.1% (3/49). This included two mechanical hardware failures, one the result of trauma and the other due to noncompliance. ConclusionsThe modified construct represents a safe and effective means of treating transverse patella fractures. Level of evidenceLevel 4.

A novel angiography-based computational modelling for assessing the dynamic stress and quantitative fatigue fracture risk of the coronary stents immediately after implantation: Effects of stent materials, designs and target vessel motions

Fluctuating stress on the implanted coronary stents within cardiac cycle is an important mechanism of fatigue fracture, which is associated with in-stent restenosis and stent thrombosis. We developed a novel computational modelling to calculate the dynamic stress of stents based on the time sequence angiography immediately after treatment. Two groups of patient-specific cases (one same stent design treated in 4 different coronary arteries and one same artery actually/virtually implanted one stent with 3 different designs) were performed the dynamic stress analysis by this computational modelling and subsequently assessed the fatigue fracture risk by Goodman method. The motion of target arteries significantly impacts on distribution of the stress and the risk of stent fracture, particularly in the site of hinge motion. Both the location of stent stress concentration in the obtuse marginal artery and the “unsafe” region in the inverse fatigue safety factor contour co-registered with the position of complete transverse fracture 13 months later after implantation. Three stents with different designs had the same location of highest stress concentration at the hinge motion site of the actually/virtually treated artery. Higher strength stent materials are significantly lower the risk of stent fracture rather than stent designs. This new computational modelling might be a useful tool in assessment of fracture risk of the implanted stent and in optimizing new design of dedicated stent treated specific coronary arteries and mechanical properties in vivo of bioresorbable scaffold during degradation process.