Search Results (65)

Background: NVD003 is an autologous, adipose tissue-derived stem cell-based tissue-engineered bone graft substitute with pro-osteogenic, anti-resorptive, and pro-angiogenic properties. Here, we describe highlights from the NVD003 preclinical development program as well as early clinical experience. Methods: NVD003 is produced in a Good Manufacturing Practice-controlled process from adipose stem cells collected during a minimally invasive liposuction procedure. The final implant is a ready-to-use moldable putty with fixed mineral content and predefined physiologic ranges of osteogenic cells and bioactive growth factors. Preclinical pharmacology studies were conducted in nude rats using a paravertebral implantation model, and subsequently, in a femoral critical-sized bone defect (CSBD) model. In a first-in-human Phase 1b/2a study, NVD003 was used for fracture osteosynthesis with classical fixation material in nine adults with recalcitrant lower limb non-union. NVD003 was also used at the discretion of treating physicians in four pediatric patients surgically treated for congenital pseudarthrosis of the tibia (CPT) with the Masquelet technique. Efficacy was evaluated as clinical healing and in terms of bone formation, bone union, and bone remodeling on radiographs and computed tomography using the extended Lane and Sandhu Scale. Results: Preclinical studies indicated that NVD003 requires cellularity for its bioactivity and moreover facilitates bone union when used as a graft material in femoral CSBD. In the clinical study, nine adult participants were successfully grafted with NVD003 and completed study follow-up to 24 months, with extended safety follow-up to 5 years ongoing. No adverse events were considered related to NVD003. Maximal bone formation occurred between 3 and 12 months post-implantation; the mean time to clinical healing was 6 months and the mean time to radiological union was 17 months. Ultimately, 89% (8/9) of patients achieved bone union without refracture. All four pediatric patients with CPT also achieved lasting bone union following grafting with NVD003. No safety signals were observed over a mean follow-up of 62.1 months. Conclusions: NVD003 represents a safe, autologous bone graft substitute product without side effects of heterotopic ossification or bone resorption. NVD003 facilitated bone union in adult and pediatric patients even under severe pathophysiological conditions. Full article

Background and Objectives: Adolescent diaphyseal clavicle fracture surgery has increased in recent years. However, the optimal operative method remains debated, particularly between elastic stable intramedullary nailing (ESIN) and plate fixation. This study compared postoperative outcomes and complication rates between ESIN and plate fixation for treating diaphyseal clavicle fractures in adolescent patients. Materials and Methods: We conducted a retrospective review of 35 adolescents who underwent surgery for diaphyseal clavicle fractures between 2010 and 2024. Patients were assigned to either the ESIN group (n = 18) or the plate fixation group (n = 17). Postoperative outcomes assessed included the Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH) score, intraoperative time, time to complete fracture union, and clavicle shortening at 1 year postoperatively. Postoperative complications were also evaluated. Results: Fracture union occurred significantly faster with ESIN than with plate fixation, specifically 3 weeks earlier (11.0 weeks vs. 14.0 weeks; p < 0.001). No significant differences were observed between the groups in QuickDASH scores, intraoperative time, or clavicle shortening at 1 year. The overall postoperative complication rate was 25.7% (9/35), with no statistically significant difference between the ESIN (27.8%) and plate fixation groups (23.5%) (p = 0.774). Refractures occurred exclusively in the plate fixation group (n = 2), while one patient in the ESIN group required early nail removal due to insertion site irritation. Conclusions: ESIN provided functional and radiographic outcomes comparable to plate fixation in adolescents with diaphyseal clavicle fractures, with a 3-week shorter time to union and a less-invasive surgical approach. Full article

In the Kelameili volcanic gas reservoir, primary hydraulic fracturing treatments in some wells take place on a limited scale, resulting in a rapid decline in production post stimulation and necessitating re-fracturing operations. However, prolonged production has led to a significant evolution in the in situ stress field, which complicates the design of re-fracturing parameters. To address this, this study adopts an integrated geology–engineering approach to develop a formation-specific geomechanical model, using rock mechanical test results and well-log inversion to reconstruct the reservoir’s initial stress field. The dynamic stress field simulations and re-fracturing parameter optimization were performed for Block Dixi-14. The results show that stress superposition effects induced by multiple fracturing stages and injection–production cycles have significantly altered the current in situ stress distribution. For Well K6, the optimized re-fracturing parameters comprised a pump rate of 12 m³/min, total fluid volume of 1200 m³, prepad fluid ratio of 50–60%, and proppant volume of 75 m³, and the daily gas production increased by 56% correspondingly, demonstrating the effectiveness of the optimized re-fracturing design. This study not only provides a more realistic simulation framework for fracturing volcanic rock gas reservoirs but also offers a scientific basis for fracture design optimization and enhanced gas recovery. The geology–engineering integrated methodology enables the accurate prediction and assessment of dynamic stress field evolution during fracturing, thereby guiding field operations. Full article

Background/Objectives: The aim of this study is to describe the characteristics of a cohort of patients who underwent surgery for septic non-union of the lower extremities. Methods: We analyzed clinical data from 74 patients affected by septic non-union of long bones in the lower extremities, treated with the Ilizarov method between January 2006 and December 2021. The primary objective of our study was to describe the time from surgery to bone union. Results: Patients had undergone a median of three previous surgical interventions, had an average bone defect of 5.4 cm, with 43.4% of patients having a Non-Union Scoring System (NUSS) > 75 points, and 46.5% of patients having been considered candidates for limb amputation in other centers. Bone union was achieved in 73 patients (98.65%), while infection resolution was achieved in 68 patients (91.89%). In 63 patients (85.13%), healing was obtained with one surgical procedure only. Only 11 re-interventions were necessary after frame removal (14.86%): 10 were due to re-fractures (13.51%) and 1 to an infection recurrence, which resulted in an amputation (1.35%). At a time of 6.01 ± 3.9 years follow-up, the Association for the Study and Application of the Methods of Ilizarov (ASAMI) scoring system indicated excellent or good outcomes in 97.3% for the bone subscale and in 89.2% for the functional subscale. The Patient Global Impression of Change (PGIC) showed that 96.8% of patients were “very much improved” or “much improved”. Patients who have suffered a more recent trauma or fewer previous surgeries achieved a better outcome. Conclusions: Despite some limitations, this study shows that treatment of septic non-unions using the Ilizarov method is both highly effective in bone and infection healing and results in a satisfactory functional outcome. The results observed in our cohort suggest that the Ilizarov method could be critically re-evaluated as a primary treatment option for these challenging cases. The clinical relevance of these findings lies in their potential to significantly alter the current treatment paradigm, by questioning the need for biologic adjuncts and local antibiotics, thereby reducing healthcare costs. Full article

The mechanisms underlying formation energy depletion after initial fracturing and post-refracturing production decline in shale oil horizontal wells remain poorly understood. This study proposes a novel numerical simulation framework for refracturing processes based on a three-dimensional fully coupled hydromechanical model. By dynamically reconfiguring the in situ stress field through integration of production data from initial fracturing stages, our approach enables precise control over fracture propagation trajectories and intensities, thereby enhancing reservoir stimulation volume (RSV) and residual oil recovery. The implementation of fully coupled hydromechanical simulation reveals two critical findings: (1) the 70 m fracture half-length generated during initial fracturing fails to access residual oil-rich zones due to insufficient fracture network complexity; (2) a 3–5° stress reorientation combined with reservoir repressurization before refracturing significantly improves fracture network interconnectivity. Field validation demonstrates that refracturing extends fracture half-lengths to 97–154 m (38–120% increase) and amplifies RSV by 125% compared to initial operations. The developed seepage–stress coupling methodology establishes a theoretical foundation for optimizing repeated fracturing designs in unconventional reservoirs, providing critical insights into residual oil mobilization through engineered stress field manipulation. Full article

Background: Pertrochanteric fractures of the proximal femur present a common challenge for traumatologists, with intramedullary nailing emerging as the preferred treatment. Complication rates are around 20%, including screw jamming, refractures, implant breakage, or medial migration, with cut-out being the most common. A tip–apex distance (TAD) of >25 mm and incorrect cephalic screw position are predictive factors for cut-out. This study assesses outcomes using the Elos intramedullary nail, based on the experience of the Department of Orthopedics and Traumatology at Ospedale Maggiore in Bologna. Methods: We conducted a retrospective cohort study of 344 patients treated with the Elos intramedullary nail for pertrochanteric femoral fractures from 1 January 2017 to 31 December 2022. The Elos^®-Intrauma nail was implanted using the standard technique. Initial X-rays classified fractures according to the AO-OTA classification, and postoperative X-rays confirmed the cephalic screw’s placement per Cleveland’s regions. Patients were divided into two groups: optimal cephalic screw position (positions 5-8-9) and other positions. We evaluated TAD, calcar-referred TAD (CalTAD), and postoperative reduction quality using Chang’s criteria. The incidence of cut-out and other complications were assessed in connection with these measurements. Results: Among the 344 patients, 227 (65.9%) had the screw in positions 5-8-9, while 117 (34.1%) had it in other positions. The median TAD was 19.47 ± 6.26 mm (range 3.96–46.6), with TAD ≤ 25 mm in 265 patients (77%). The median CalTAD was 22.37 ± 5.65 mm (range 8.75–45.3), with CalTAD ≤ 25 mm in 231 patients (67.1%). According to Chang’s criteria, 8 cases (2.3%) had poor reduction, 139 cases (40.4%) had acceptable reduction, and 197 cases (57.3%) had excellent reduction. Cut-out occurred in four cases (1.19%). Multivariate analysis revealed only poor reduction and TAD > 25 mm as independent predictors of cut-out (p < 0.05), while cephalic screw position, CalTAD, and fracture type did not impact cut-out incidence. Conclusions: This study indicates that optimal TAD and quality of reduction are crucial for minimizing cut-out risks. The Elos intramedullary nail shows favorable outcomes with a low cut-out incidence when these parameters are met. Emphasis should be placed on achieving a TAD ≤ 25 mm and excellent reduction quality to reduce complications. Full article

Background: Peri-implant femoral fractures are increasingly prevalent among the elderly, often leading to re-fractures due to osteoporosis and implant stress. Whole span plating (WSP) has been proposed as a surgical approach to mitigate this risk. Methods: A retrospective study was conducted on 10 patients (mean age: 79.5 years) who underwent WSP for peri-implant femoral fractures between April 2020 and March 2023. Fractures were classified using the Vancouver, NPPIF, and Lewis and Rorabeck systems. Surgical indication required meeting at least two of the following criteria: age ≥ 70 years, history of fragility fracture(s), high fall risk, severe osteoporosis, extensive fracture pattern, or no implant loosening. Results: No re-fractures were observed during a mean follow-up period of 14.5 months. Although 90% of patients required red blood cell transfusions (mean volume: 3.8 units), early weight-bearing was achieved in most cases. Four patients had received osteoporosis treatment, highlighting the need for integrated bone health management. Conclusions: WSP appears to be a feasible and safe surgical option for high-risk patients with peri-implant femoral fractures, potentially reducing the incidence of subsequent fractures. Further studies with larger cohorts and longer follow-up are warranted. Full article

Background: Pediatric diaphyseal forearm fractures, often caused by sports or leisure activities, require treatment based on fracture stability. While stable fractures can be managed conservatively, unstable fractures typically require surgery, with elastic stable intramedullary (IM) nailing (ESIN) being the gold standard. Bioabsorbable IM nails (BINs) offer an alternative by eliminating the need for implant removal surgery. Methods: Between May 2023 and January 2025, we consecutively managed 161 children with poly-L-lactic-co-glycolic acid (PLGA) BINs in two healthcare centers for diaphyseal forearm fracture and evaluated every reported difficulty and complication of resorbable IM nails. Results: Seven unique peri- or postoperative events occurred during the study period. Even with a high success rate, some complications occurred during the study period. Difficulties and complications were mainly dependent on the surgical technique. Iatrogenic complications such as bone cortex perforation and implant end split were evaluated, along with anatomical variations like focal and general medullary cavity stenosis narrowings that affected implant insertion. Secondary malalignment, one early (2 months) refracture, and one recurrent fracture (2 years) were also noted. Conclusions: Although BINs reduce the need for a second surgery, careful planning, technique, and follow-up are crucial for optimal outcomes. Further research is needed to assess long-term results and complications. Full article

Objectives: The aim of this study was to investigate the incidence of vertebral refractures following percutaneous kyphoplasty (PKP) and to explore risk factors for augmented vertebral refractures, thereby assisting spinal surgeons in clinical practice. Methods: We analyzed the records of 495 patients with single-segment osteoporotic vertebral compression fractures (OVCFs) who were treated with single-entry PKP at our institution from March 2016 to August 2022. Univariate analysis, binary logistic regression, and ROC curve analysis were performed to determine potential risk factors, independent risk factors, and discrimination ability. Results: A total of 168 patients were included in the study, with a median follow-up duration of 7.00 months. In total, 143 patients did not experience vertebral refracture after surgery, while 25 patients did, including 22 augmented vertebral fractures and 3 adjacent vertebral compression refractures. The correction rate of the Cobb angle (p < 0.001; OR = 1.070) and postoperative anti-osteoporosis treatment (p = 0.002; OR = 0.021) were independently associated with augmented vertebral refracture. The ROC curves showed that these variables demonstrated satisfactory predictive values for augmented vertebral refracture. Conclusions: A high degree of restoration of the Cobb angle was the factor contributing to vertebral refracture after PKP. Conversely, postoperative anti-osteoporosis treatment was observed to be a protective factor against subsequent vertebral refracture. Full article

Refracturing is an important technology for tapping remaining oil and gas areas and enhancing recovery in old oilfields. However, a complete and detailed refracturing timing optimization scheme has not yet been proposed. In this paper, based on the finite volume method and the embedded discrete fracture model, a new coupled fluid flow/geomechanics pore-elastic-fractured reservoir model is developed. The COMSOL 3.5 commercial software was used to verify the accuracy of our model, and by studying the influence of matrix permeability, initial stress difference, cluster spacing, and fracture half-length on the orientation of maximum horizontal stress, a timing optimization method for refracturing is proposed. The results of this paper show that the principle of optimizing the refracturing timing is to avoid the time window where the percentage of Type I (Type I indicates that stress inversion has occurred, $0^{\circ }\le \alpha \le {20}^{\circ }$; Type II indicates that the turning degree is strong, ${20}^{\circ }<\alpha \le {70}^{\circ }$; and Type III indicates less stress reorientation, ${70}^{\circ }<\alpha \le {90}^{\circ }$) stress reorientation area is relatively large, so that the fractures can extend perpendicular to the horizontal wellbore. At the same time, the simulation results show that with the increase in production time, the percentage of Type I and Type II increases first and then decreases, while the percentage of Type III decreases first and then increases. When the reservoir permeability, stress difference, and cluster spacing are larger, the two types of refracturing measures can be implemented earlier. But, with the increase in fracture half-length, the timing of refracturing Method I is earlier, and the timing of refracturing Method II is later. The research results of this paper are of great significance to the perfection of the refracturing theory and the optimization of refracturing design. Full article

This study presents an in-depth analysis of a refractured tight oil well, focusing on both the initial and subsequent refracturing operations. After refracturing, daily oil production surged from 0.8 to 15.0 tons. The well sustained natural flow for 100 days before transitioning to pump-assisted production, resulting in an additional cumulative oil production of 1412 tons. Leveraging distributed temperature sensing (DTS), high-resolution temperature monitoring was performed, revealing key insights into the behavior of both newly created and existing fractures. Older perforation stages outperformed newer ones, with average daily oil production of 4.66 m³ for older stages and 3.49 m³ for newer stages under a 2 mm choke size. Moreover, CO₂ pre-fracturing significantly enhanced oil production, with the stages receiving CO₂ injection achieving a median daily oil output of 4.04 m³, compared to 3.55 m³ for non-CO₂ stages. These results demonstrate the effectiveness of integrating advanced monitoring techniques and innovative fracturing methods to optimize refracturing strategies, ultimately enhancing hydrocarbon recovery in tight oil reservoirs. Full article

Poorly producing wells in sandstone gas reservoirs are often refractured to enhance production. Considering the mutual interference of initial/refractured fractures, conductivity dynamic evolution, non-uniform inflow, and variable mass flow in the fracture comprehensively, a semi-analytical reservoir-fracture coupled production model fusing spatial and time separation methods is introduced to model refractured well performance. The proposed model is verified by CMG. The field applications indicate that the refracture job should be carried out when production is lower than the desired value. Restoring the C_f-ini and constructing the C_f-ref can increase productivity, which increases over 8 D•cm. The production growth rate just obtained a slight improvement. The production increased significantly with L_f-ini increasing from 120~270 m and L_f-ref increasing from 100~150 m. Hence, it is essential to extend the L_f-ini under engineering conditions. The k_s/k_m = 10 can obviously increase production, but further enlarging k_s does not contribute to well performance. Conversely, further producing larger b_s is vital to enhancing production. Subsequently, the optimal parameter combinations (d_s > L_f-ini > L_f-ref > C_f-ini > k_s > C_f-ref) for well(X1) are carried out by orthogonal experiments. This work proposes a novel method to simulate refractured vertical well performance in tight gas reservoirs for refracture optimization. Full article

Background: This biomechanical in vitro study compared two kyphoplasty devices for the extent of height reconstruction, load-bearing capacity, cement volume, and adjacent fracture under cyclic loading. Methods: Multisegmental (T11–L3) specimens were mounted into a testing machine and subjected to compression, creating an incomplete burst fracture of L1. Kyphoplasty was performed using a one- or two-compartment device. Then, the testing machine was used for a cyclic loading test of load-bearing capacity to compare the two groups for the amount of applied load until failure and subsequent adjacent fracture. Results: Vertebral body height reconstruction was effective for both groups but not statistically significantly different. After cyclic loading, refracture of vertebrae that had undergone kyphoplasty was not observed in any specimen, but fractures were observed in adjacent vertebrae. The differences between the numbers of cycles and of loads were not statistically significant. An increase in cement volume was strongly correlated with increased risks of adjacent fractures. Conclusion: The two-compartment device was not substantially superior to the one-compartment device. The use of higher cement volume correlated with the occurrence of adjacent fractures. Full article

The technique of refracturing is an effective method to solve the rapid decline in oil well production caused by factors such as severe reservoir energy loss and fracture failure after the initial hydraulic fracturing of low-permeability reservoirs. The key to designing refracturing lies in establishing a model for evaluating the potential fracturing layers. Based on the geological characteristics of the low-permeability conglomerate reservoir in the Lower Wuerhe area of the Eig District of the Xinjiang Oilfield, this paper studies the influence of different development approaches on the distribution pattern of remaining oil in the reservoir. A coupled model of remaining oil distribution and the in situ stress field is established and discusses the characteristics of the four-dimensional in situ stress field under different development modes. This paper analyzes the influence of geological factors and well network factors on the distribution of residual oil, and analyzes the influence of various factors, such as reservoir properties and injection and extraction parameters, on ground stress. Based on the residual oil distribution and ground stress changes, an evaluation method for screening potential fractured layers in reservoirs with different development modes (water injection development and depletion development) is developed. Full article

During the temporary plugging fracturing (TPF) process, the pressure response and pumping behavior significantly differ from those observed during conventional fracturing fluid pumping. Once the temporary plugging agent (TPA) forms a plug, subsequent fracture initiation and propagation become more intricate due to the influence of the TPA and early fractures. Factors such as concentration, particle size, and ratio of the TPA notably affect the effectiveness of TPF. This study employs a true triaxial hydraulic fracturing simulation system to conduct TPF experiments with varying particle size combinations and concentrations at both in-fracture and in-stage locations. The impact of different TPA parameters on the plugging effectiveness is assessed by analyzing the morphology of the induced fractures and the characteristics of pressure curves post experiment. Results indicate that combining dfferent particle sizes enhances plugging effectiveness, with a combination of smaller and larger particles exhibiting superior plugging effectiveness, resulting in a pressure increase of over 25.9%. As the concentration of the TPA increases, the plugging fracture pressure rises, accompanied by rapid pressure response and significant plugging effects, leading to more complex fracture morphology. For shale reservoirs, the density of bedding planes (BPs) influences the morphology and width of conventional hydraulic fractures, thereby affecting the effectiveness of subsequent refracturing. Rock samples with a relatively low BP density demonstrate effective plugging initiation both in-fracture and in-stage, facilitating the formation of complex fracture networks. Conversely, specimens with a relatively high BP density exhibit superior plugging effectiveness in-stage compared to in-fracture plugging. Full article