Acute Bony Injuries of Hand and Wrist

Acute bony injuries to the hand and wrist are very common after a fall on an outstretched hand. In the wrist, distal radius fractures are the most common; isolated distal ulna fractures are uncommon. More serious injuries to the wrist include complicated fracture-dislocation injuries such as perilunate dislocations. At the carpal level, scaphoid fractures are the most common followed by fractures of the dorsal side of the triquetrum. The metacarpals often fracture, most commonly the base of the thumb and the subcapital region of the fifth metacarpal. In the fingers, we encounter many different types of fractures, often avulsions reflecting underlying soft tissue pathology (e.g., mallet finger). Dislocations are common in the fingers, predominantly in the distal interphalangeal joints. From an imaging standpoint, conventional radiography is always the initial examination. Complex (intra-articular) fractures, fracture-dislocation injuries, and a strong clinical suspicion of radiographically occult fractures need to be further evaluated for decision making regarding treatment. Computed tomography is the primary imaging modality of choice for the first two. In the latter, magnetic resonance imaging can be preferable, depending on clinical suspicion and the local situation in the associated hospital.

Mandibular Ramus Fractures: A Proposed Classification

Aims: The purpose of this article was to study and devise a classification of fracture patterns of the mandibular ramus to facilitate management. Methods: Mandibular ramus fracture demographics in literature were reviewed along with evaluation of the patients diagnosed with mandibular ramus fractures who had reported to the emergency/outpatient clinic of our Institute in the last 5 years. Epidemiology of these ramus fractures was studied, and these ramus fractures were categorized into repetitive patterns on the basis of radiological observations in an effort to achieve a simplified classification. Results: A total of 1372 trauma patients were diagnosed with mandibular fractures, of which an incidence of 2.4% was recorded for ramus fractures. These were predominantly in males and mainly due to road traffic accidents commonly in people driving two-wheeler vehicles (64%). Ramus fractures seldom occur in isolation. Five predictable fracture patterns were observed and accordingly classified as types I to V. Type I was the most common and type IV the least. Open reduction was done in 45.5% patients with non-compression plating systems. Satisfactory aesthetic and functional outcomes were achieved in all patients. Conclusion: The mandibular ramus fractures although rare need to be well understood and demarcated. The classification highlights the importance of this mandibular buttress and focuses on the importance of its technically and anatomically more complicated fracture treatment. Future studies are needed to compare the modalities of management.

Defective Proliferation and Osteogenic Potential with Altered Immunoregulatory phenotype of Native Bone marrow-Multipotential Stromal Cells in Atrophic Fracture Non-Union

Bone marrow-Multipotential stromal cells (BM-MSCs) are increasingly used to treat complicated fracture healing e.g., non-union. Though, the quality of these autologous cells is not well characterized. We aimed to evaluate bone healing-related capacities of non-union BM-MSCs. Iliac crest-BM was aspirated from long-bone fracture patients with normal healing (U) or non-united (NU). Uncultured (native) CD271highCD45low cells or passage-zero cultured BM-MSCs were analyzed for gene expression levels, and functional assays were conducted using culture-expanded BM-MSCs. Blood samples were analyzed for serum cytokine levels. Uncultured NU-CD271highCD45low cells significantly expressed fewer transcripts of growth factor receptors, EGFR, FGFR1, and FGRF2 than U cells. Significant fewer transcripts of alkaline phosphatase (ALPL), osteocalcin (BGLAP), osteonectin (SPARC) and osteopontin (SPP1) were detected in NU-CD271highCD45low cells. Additionally, immunoregulation-related markers were differentially expressed between NU- and U-CD271highCD45low cells. Interestingly, passage-zero NU BM-MSCs showed low expression of immunosuppressive mediators. However, culture-expanded NU and U BM-MSCs exhibited comparable proliferation, osteogenesis, and immunosuppression. Serum cytokine levels were found similar for NU and U groups. Collectively, native NU-BM-MSCs seemed to have low proliferative and osteogenic capacities; therefore, enhancing their quality should be considered for regenerative therapies. Further research on distorted immunoregulatory molecules expression in BM-MSCs could potentially benefit the prediction of complicated fracture healing.

Deformation Behavior between Hydraulic and Natural Fractures Using Fully Coupled Hydromechanical Model with XFEM

There has been a growing consensus that preexisting natural fractures play an important role during stimulation. A novel fully coupled hydromechanical model using extended finite element method is proposed. This directly coupled scheme avoids the cumbersome process during calculating the fluid pressure in complicated fracture networks and translating into an equivalent nodal force. Numerical examples are presented to simulate the hydraulic fracture propagation paths for simultaneous multifracture treatments with properly using the stress shadow effects for horizontal wells and to reveal the deformation response and interaction mechanism between hydraulic induced fracture and nonintersected natural fractures at orthotropic and nonorthotropic angles. With the stress shadow effects, the induced hydraulic flexural fracture deflecting to wellbore rather than transverse fracture would be formed during the progress of simultaneous fracturing for a horizontal well. The coupled hydromechanical simulation reveals that the adjacent section to the intersection is opened and the others are closed for orthogonal natural fracture, while the nonorthogonal natural fracture is activated near the intersection firstly and along the whole section with increasing perturbed stresses. The results imply that the induced hydraulic fracture tends to cross orthotropic natural fracture, while it is prior to being arrested by the nonorthotropic natural fracture.

Fracture Mechanism of Polypropylene-Kenaf Composite under Cyclic Loading

Mechanism of fracture of polypropylene composite reinforced by kenaf fiber under cyclic loading was investigated. Weight fraction of the composite used is 50% polypropylene and 50% kenaf fiber with random fiber orientation. Skins of composite that contains polypropylene dominant fraction are formed on both surfaces. The experiments were performed with flat specimen under cyclic flexural loading with constant displacement. Cyclic softening was detected by hysteresis loop of a local area. Deformation of the specimen was measured from the observed cycles. Fracture features were investigated using optical microscope and scanning electron microscope. The result shows that polypropylene-kenaf composite with 50%-50% fraction with random fiber orientation has complicated fracture features. The damage of the composite started from internal part. The surface crack proceeded after the internal damage. Moreover, it is discussed that some of fibers were covered by only thin matrix. The strength of specimen was determined the fracture behavior of fibers.

Shale Reservoirs Multi-Fracture Fracturing Technique and Studies on Reservoirs Stresses

Theoretical studies have shown that the generation of the hydraulic fractures reduces or even reverses the stress anisotropy near the fractures and results in increasing the complexity of fractures. A finite element model was established in which the pore pressure elements were used to simulate the behavior of porous media and the pore pressure cohesive elements were adopted to catch the characters of hydraulic fractures. A special fracturing manner was adopted to create complicated fracture networks by reducing or even reversing the stress anisotropy between fractures. The geometries of hydraulic fractures, strains, stresses, pore pressure distributions and fluid pressures within the fractures are obtained. The results of the model are fit well with the corresponding theoretical data. The simulation results show that the stress anisotropy is reduced by the generation of the hydraulic fractures, multiple parallel transverse fractures of horizontal well even reverse the stress anisotropy in some place of the reservoir. The simulation results validate the feasibility of the theoretical studies and the expected complex network fractures could be created by adopting special fracturing manner.