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Introduction: The therapeutic management of calcaneal fractures is currently a major source of controversy in the literature. There is no consensus on the need to treat these injuries conservatively or surgically, nor on the criteria for deciding one option or the other. Although the gold standard has classically been the open approach and osteosynthesis, there are currently minimally invasive techniques that also report good results. Our objective is to present our results and experience with the MBA® Orthofix external fixator in a series of cases of calcaneal fractures. Methods: We performed a retrospective observational study in our center, between the years 2019 and 2021, of Sanders types II–IV calcaneal fractures operated with MBA® Orthofix external fixator. We recorded a total of 38 patients, 42 fractures. We registered demographic information, intraoperative, postoperative, radiological and functional parameters, using the American Orthopedic Foot and Ankle Society (AOFAS), Manchester-Oxford Foot Questionnaire (MOXFQ), EQ-5D and VAS scales. Results: A total of 26 men and 12 women were included, and the median age was 38 years. Mean follow-up was 24,4 months (6, 8–40, 1). The average time to surgery was 7 days and partial loading was started at 2.5 weeks after external fixation, which was removed at 9.2 weeks. The average Böhler angle correction was 7, 4°, Gissane − 12,2°, length 2 mm and calcaneal width was reduced by 5 mm. We recorded two superficial infections, one peroneal entrapment and three subtalar arthrodesis due to post-traumatic osteoarthritis. The AOFAS obtained was 79.1 + / − 15.7 points, MOXFQ 20.1 + / − 16.1 points, EQ-5D 0.84 + / − 0.2 and VAS 3.3 + / − 1.9. Conclusion: The external fixator is an excellent surgical alternative for complex articular fractures of the calcaneus, obtaining clinical and radiological results comparable to other osteosynthesis techniques and significantly reducing soft tissue complications. [ABSTRACT FROM AUTHOR]

The Xujiahe Formation in western Sichuan has complex geological characteristics, fractures and fractures, and is prone to collapse in drilling. In this paper, the in-situ stress field around the wellbore, pore pressure, internal pressure in the wellbore and additional stress field generated by fluid flow are taken into account, and combined with the mechanical strength of rock in the target block, the in-situ stress parameters are calculated, the collapse pressure model of fractured formation is established, and the formation pressure profile of the well area is obtained, so as to predict the safe drilling fluid density window. The results show that the accuracy of the in-situ stress model is high, and the maximum error is 1.3%, which meets the engineering requirements. In the target block, the collapse pressure of Section 5 of Xinsheng 101 well and Section 5 – Section 3 of Xin601 well is high, reaching 1.8 g/cm3, and the safe drilling fluid density is narrow. Therefore, the drilling fluid density should be carefully designed to ensure the stability of borehole wall and prevent the occurrence of borehole wall collapse caused by too low drilling fluid density. [ABSTRACT FROM AUTHOR]

Tendons connect muscle to bone and play an integral role in bone and joint alignment and loading. Tendons act as pulleys that provide anchorage of muscle forces for joint motion and stability, as well as for fracture reduction and realignment. Patients that experience complex fractures also have concomitant soft tissue injuries, such as tendon damage or rupture. Tendon injuries that occur at the time of bone fracture have long-term ramifications on musculoskeletal health, yet these injuries are often disregarded in clinical treatment and diagnosis for patients with bone fractures as well as in basic science approaches for understanding bone repair processes. Delayed assessment of soft tissue injuries during evaluation of trauma can lead to chronic pain, dysfunction, and delayed bone healing even following successful fracture repair, highlighting the importance of identifying and treating damaged tendons early. Treatment strategies for bone repair, such as mechanical stabilization and biological therapeutics, can impact tendon healing and function. Because poor tendon healing following complex fracture can significantly impact the function of tendon during bone fracture healing, a need exists to understand the healing process of complex fractures more broadly, beyond the healing of bone. In this review, we explored the mechanical and biological interaction of bone and tendon in the context of complex fracture, as well as the relevance and potential ramifications of tendon damage following bone fracture, which has particular impact on patients that experience complex fractures, such as from combat, automobile accidents, and other trauma. [ABSTRACT FROM AUTHOR]

A new well test model for a vertical fractured well is developed based on a discrete-fracture model in which the fractures are discretized as one dimensional (1-D) entities. The model overcomes the weakness of complex meshing, a large number of grids, and instability in conventional stripe-fracture models. Then, the discrete-fracture model is implemented using a hybrid element finite-element method. Triangular elements are used for matrix and line elements for the fractures. The finite element formulation is validated by comparing with the semi-analytical solution of a single vertical fractured well. The accuracy of the approach is shown through several examples with different fracture apertures, fracture conductivity, and fracture amount. Results from the discrete-fracture model agree reasonably well with the stripe-fracture model and the analytic solutions. The advantages of the discrete-fracture model are presented in mesh generation, computational improvement, and abilities to handle complex fractures like wedge-shaped fractures and fractures with branches. Analytical results show that the number of grids in the discrete-fracture model is 10 % less than stripe-fracture model, and computational efficiency increases by about 50 %. The more fractures there are, the more the computational efficiency increases. [ABSTRACT FROM AUTHOR]

A new experimental model has been designed to simulate the influence of a natural fracture network on the propagation geometry of hydraulic fractures in naturally fractured formations using a tri-axial fracturing system. In this model, a parallel and symmetrical pre-fracture network was created by placing cement plates in a cubic mold and filling the mold with additional cement to create the final testing block. The surface of the plates will thus be weakly cemented and form pre-fractures. The dimension and direction of the pre-fractures can be controlled using the plates. The experiments showed that the horizontal differential stress $$\Updelta \sigma$$ and the angle $$\Updelta \theta$$ between the maximum horizontal principal in situ stress and the pre-fracture are the dominating factors for the initiation and propagation of hydraulic fractures. For $$\Updelta \theta = 90^\circ$$ and $$\Updelta \sigma \ge 2{\text{ MPa}}$$ or $$\Updelta \theta = 60^\circ$$ and $$\Updelta \sigma \ge 4{\text{ MPa}}$$, the direction of the initiation and propagation of the hydraulic fractures are consistent with or deviate from the normal direction of the pre-fracture. When the hydraulic fractures approach the pre-fractures, the direction of the hydraulic fracture propagation will be consistent with the normal direction of the pre-fracture. Otherwise, the hydraulic fracture will deflect and perpendicularly cross the parallel and symmetric pre-fracture network. For $$\Updelta \theta = 90^\circ$$ and $$\Updelta \sigma < 2{\text{ MPa}},\,\Updelta \theta = 60^\circ$$, and $$\Updelta \sigma < 4{\text{ MPa}}$$ or $$\Updelta \theta = 45^\circ$$ and $$\Updelta \sigma = 4 - 8{\text{ MPa}}$$, before the hydraulic fracture and the pre-fractures intersect, the direction of the hydraulic fracture propagation remains unchanged, and the pre-fractures open or dilate when the hydraulic fracture propagates to the intersection point, forming a complicated hydraulic fracture network with the propagation region of the overall hydraulic fracture network taking the shape of an ellipse. In this condition, the complexity level of the hydraulic fracture is controlled by the net pressure, the compressive normal stress acting on the pre-fractures, the shearing strength and the cohesion strength of the planes of weakness. The conclusions of this research are inconsistent with the formulation of the approach angle that has been widely accepted by previous studies. The principle of hydraulic fracture propagation is that it follows the least resistance, the most preferential propagation, and the shortest propagation path. [ABSTRACT FROM AUTHOR]

Complex fractures of the distal radius are articular lesions and comminuted at the level of the epiphysis and metaphysis. Their treatment is difficult and in most cases surgical. Of all the different osteosynthesis methods available, internal fixation with plate and screws is the most commonly used. In particular, angular stability plates are superior in terms of rigidity and stability to conventional volar and dorsal plates. DVR plate has these mechanical characteristics, and its low profile has reduced frictions with surrounding soft tissues. For these reasons, this device implanted through a single volar approach, can stabilize the majority of volarly and dorsally displaced unstable distal radius fractures. In this study, 48 patients, affected by complex fractures of the distal radius treated with DVR volar plates, were assessed by the Mayo modified wrist score, the Italian version of the disability of the arm, shoulder and hand. The satisfactory results observed confirm the efficacy of this device. [ABSTRACT FROM AUTHOR]

Tibial plateau fractures are complex injuries which, if not adequately treated, can lead to invalidating sequelae. They constitute on average about 1% of all fractures, and up to 8% in patients over 65 years, and can be caused by both high- and low-energy trauma. Unlike in younger subjects, treatment of tibial plateau fractures in the elderly is not univocal and depends on the patient’s functional needs, bone quality and systemic comorbidities. In this retrospective study, 49 patients with a mean age of 72 years, who underwent surgical treatment of a tibial plateau fracture, were assessed by the Rasmussen’s clinical and radiological grading systems. Clinical and radiographic outcomes were satisfactory in 75.5 and 59.1% of cases, respectively. Data were also analyzed, in terms of fracture type, age and gender, to detect any statistically significant correlation between these parameters and clinical and radiographic outcomes. [ABSTRACT FROM AUTHOR]