During the last decades, effective pain reduction and early mobilization were identified as the central priorities in therapy of insufficiency fractures of the pelvis. For operative treatment minimally-invasive stabilization techniques are favored. While there is consensus on the significance of sufficient dorsal stabilization the role of additional fixation of the anterior fracture component stays under discussion. Within the present study we developed an internal ring fixator system (RingFix) with the question whether an in-itself-closed construct can improve stability of the entire ring structure. RingFix was evaluated on an osteoporotic bone model with a standardized FFP IIIc fracture within an established biomechanical setup regarding its primary stabilization potential. Further, it was compared to transiliac-transsacral screw fixation with and without stabilization of the anterior fracture component. The transiliac-transsacral fixation with separate screw fixation of the anterior fracture showed significantly higher stability than the RingFix and the transiliac-transsacral screw fixation without anterior stabilization. Our results show that stabilization of the anterior fracture component relevantly improves the stability of the entire ring construct. As a bridging stabilizer, RingFix shows biomechanical advantages over an isolated dorsal fracture fixation, but inferior results than direct stabilization of the single fracture components.

暂无摘要。

The repair and regeneration of maxillofacial bone defects are major clinical challenges. Titanium (Ti)-magnesium (Mg) composites are a new generation of revolutionary internal fixation materials encompassing the mechanical strength and bioactive advantages of Ti and Mg alloys, respectively. This study was aimed to construct a Ti-Mg composite internal plate/screw fixation system to fix and repair bone defects. Further, the effects of different internal fixation systems on bone repair were analyzed through radiological and histological analyses. Notably, Ti6Al4V with rolled Mg foil was used as the experimental group, and a bone defect model of transverse complete amputation of the ulna in rabbits similar to the clinical condition was established. The internal fixation system with the highest osteogenic efficiency was selected based on in vivo results, and the direct and indirect bone repair abilities of the selected materials were evaluated in vitro. Notably, the thin Mg foil-Ti6Al4V internal fixation system exhibited the best fixation effect in the bone defect model and promoted the formation of new bone and early healing of bone defect areas. In vitro, the thin Mg foil-Ti6Al4V composite enhanced the activity of MC3T3-E1 cells; promoted the proliferation, adhesion, extension, and osteogenic differentiation of MC3T3-E1 cells; and regulated new bone formation. Further, it also promoted the polarization of RAW264.7 cells to M2 macrophages, induced the osteogenic immune microenvironment, and indirectly regulated the bone repair process. Therefore, a internal fixation system holds a promising potential for the internal fixation of maxillofacial bone defects. Our findings provide a theoretical and scientific basis for the design and clinical application of Ti-Mg internal fixation systems.

Surgical treatment has been established as the standard method for the treatment of intertrochanteric fractures in the elderly. The design of internal fixation devices has become the key to improve surgical outcomes and reduce postoperative complications. Centered on optimizing biomechanical performance and minimally invasive implantation, coupled with continuous material improvements, the design philosophy of internal fixation devices has also been constantly evolving. There have been several milestone advancements, such as the transition from eccentric fixation to central fixation, the adoption of sliding compression fixation, the replacement of traditional screws with spiral blades, and the shift from single to double (combination) nails. However, the incidence of internal fixation-related complications has remained at a relatively high level of 5% to 10%, without significant breakthroughs. Increasing evidence suggests that in-depth analysis of the anatomy, physiological mechanisms, and mechanical transmission characteristics of the proximal femur can help elucidate the root causes of internal fixation failures. Based on this, the proximal femoral bionic nail (PFBN) has emerged as a new design concept. By fully mimicking the anatomical, mechanical, and biological characteristics of the proximal femur, the PFBN can regulate the local mechanical environment, providing a revolutionary solution and a new approach for the treatment of proximal femoral fractures. This innovative design also has the potential to drive the paradigm shift in the treatment strategies of other fractures.
手术是治疗老年股骨转子间骨折的首选方法，内固定物的设计是提高手术效果、减少术后并发症的关键。以优化生物力学性能和微创植入为核心，随着材料的不断改进，内固定物的设计理念也在不断演进。数十年间出现了多项里程碑式进展，如偏心固定转向中心固定、滑动加压固定的应用、传统螺钉改为螺旋刀片，单钉改为双钉（组合）等，但内固定相关并发症的发生率仍为5%~10%，难以实现质的突破。越来越多的证据表明，深入分析股骨近端的解剖、生理学特点及力学传导特性，有助于阐释内固定失败的根本原因。基于此，股骨近端仿生髓内钉应运而生，通过完全模拟股骨近端的解剖、力学、生物学特性，调节局部力学环境，为治疗股骨近端骨折提供了新思路，亦有助于带动其他骨折治疗策略的范式变革。.

BACKGROUND: In recent years, the zero-profile implant (Zero-p) has emerged as a promising internal fixation technique. Although studies have indicated its potential superiority over conventional cage-plate implant (Cage-plate) in the treatment of degenerative cervical spondylosis, there remains a lack of definitive comparative reports regarding its indications, safety, and efficacy.
METHODS: A computerized search was conducted on English and Chinese databases, including PubMed, Web of Science, Cochrane Library, EMBASE, CNKI, Wanfang and VIP. Additionally, a manual search was meticulously carried out on Chinese medical journals, spanning from the inception of the respective databases until August 2023. The meta-analysis utilized a case-control study approach and was executed through the utilization of RevMan 5.3 software. Stringent quality evaluation and data extraction procedures were implemented to guarantee the reliability and validity of the findings.
RESULTS: Nine high-quality studies with 808 patients were included. Meta-analysis showed that the operation time (MD = - 13.28; 95% CI (- 17.53, - 9.04), P < 0.00001), intraoperative blood loss (MD = - 6.61; 95% CI (- 10.47, - 2.75), P = 0.0008), incidence of postoperative dysphagia at various time points: within the first month after surgery (OR = 0.36; 95% CI (0.22, 0.58), P < 0.0001), 1-3 months after surgery (OR = 0.20; 95% CI (0.08, 0.49), P = 0.0004), the final follow-up (OR = 0.21; 95% CI (0.05, 0.83), P = 0.003) and the rate of postoperative adjacent disc degeneration (OR = 0.46; 95% CI (0.25, 0.84), P = 0.01) were significantly lower in the Zero-p group than in the Cage-plate group. Additionally, was also significantly lower in the Zero-p group. However, there were no significant differences in the JOA score, the final follow-up NDI score, surgical segmental fusion rate, postoperative height of adjacent vertebrae, or postoperative subsidence rate between the two groups.
CONCLUSIONS: In summary, when treating single-segment degenerative cervical spondylosis, both internal fixation techniques are reliable and effective. However, Zero-P  implant offer several advantages over cage-plate implant, including shorter operation duration, less intraoperative blood loss, reduced postoperative dysphagia, and slower adjacent disc degeneration. Additionally, Zero-P implant has a broader application space, making them a preferred choice in certain cases.

BACKGROUND: To elucidate the differences in mechanical performance between a novel axially controlled compression spinal rod (ACCSR) for lumbar spondylolysis (LS) and the common spinal rod (CSR).
METHODS: A total of 36 ACCSRs and 36 CSRs from the same batch were used in this study, each with a diameter of 6.0 mm. Biomechanical tests were carried out on spinal rods for the ACCSR group and on pedicle screw-rod internal fixation systems for the CSR group. The spinal rod tests were conducted following the guidelines outlined in the American Society for Testing and Materials (ASTM) F 2193, while the pedicle screw-rod internal fixation system tests adhered to ASTM F 1798-97 standards.
RESULTS: The stiffness of ACCSR and CSR was 1559.15 ± 50.15 and 3788.86 ± 156.45 N/mm (P < .001). ACCSR\'s yield load was 1345.73 (1297.90-1359.97) N, whereas CSR\'s was 4046.83 (3805.8-4072.53) N (P = .002). ACCSR\'s load in the 2.5 millionth cycle of the fatigue four-point bending test was 320 N. The axial gripping capacity of ACCSR and CSR was 1632.53 ± 165.64 and 1273.62 ± 205.63 N (P = .004). ACCSR\'s torsional gripping capacity was 3.45 (3.23-3.47) Nm, while CSR\'s was 3.27 (3.07-3.59) Nm (P = .654). The stiffness of the pedicle screws of the ACCSR and CSR group was 783.83 (775.67-798.94) and 773.14 (758.70-783.62) N/mm (P = .085). The yield loads on the pedicle screws of the ACCSR and CSR group was 1345.73 (1297.90-1359.97) and 4046.83 (3805.8-4072.53) N (P = .099).
CONCLUSIONS: Although ACCSR exhibited lower yield load, stiffness, and fatigue resistance compared to CSR, it demonstrated significantly higher axial gripping capacity and met the stress requirement of the human isthmus. Consequently, ACCSR presents a promising alternative to CSR for LS remediation.

METHODS: We constructed finite element (FE) models of the cervical spine consisting of C2-C7 and predicted the biomechanical effects of different surgical procedures and instruments on adjacent segments, internal fixation systems, and the overall cervical spine through FE analysis.
OBJECTIVE: To compare the biomechanical effects between the zero-profile device and cage-plate device in skip-level multistage anterior cervical discectomy and fusion (ACDF).
BACKGROUND: ACDF is often considered the standard treatment for degenerative cervical spondylosis. However, the selection of surgical methods and instruments in cases of skip-level cervical degenerative disk disease is still controversial.
METHODS: Three FE models were constructed, which used noncontiguous 2-level Zero-P (NCZP) devices for C3/4 and C5/6, a noncontiguous 2-level cage-plate (NCCP) for C3/4 and C5/6, and a contiguous 3-level cage-plate (CCP) for C3/6. Simulate daily activities in ABAQUS. The range of motion (ROM), von Mises stress distribution of the endplate and internal fixation system, and intervertebral disk pressure (IDP) of each model were recorded and compared.
RESULTS: Similar to the stress of the cortical bone, the maximum stress of the Zero-P device was higher than that of the CP device for most activities. The ROM increments of the superior, inferior, and intermediate segments of the NCZP model were lower than those of the NCCP and CCP models in many actions. In terms of the IDP, the increment value of stress for the NCZP model was the smallest, whereas those of the NCCP and CCP models were larger. Similarly, the increment value of stress on the endplate also shows the minimum in the NCZP model.
CONCLUSIONS: Noncontiguous ACDF with zero profile can reduce the stress on adjacent intervertebral disks and endplates, resulting in a reduced risk of adjacent segment disease development. However, the high cortical bone stress caused by the Zero-P device may influence the risk of fractures.

OBJECTIVE: Expandable transforaminal lumbar interbody fusion (TLIF) cages were designed to address the limitations of static cages. Bilateral cage insertion can potentially enhance stability, fusion rates, and segmental lordosis. However, the benefits of unilateral versus bilateral expandable cages with varying sizes in TLIF remain unclear. This study used a validated finite element spine model to compare the biomechanical properties of L5-S1 TLIF by using differently sized expandable cages inserted unilaterally or bilaterally.
METHODS: A finite element model of X-PAC expandable lumbar cages was created and used at the L5-S1 level. This model had cage dimensions of 9 mm in height, 15° in lordosis, and varying widths and lengths. Various placements (unilateral vs bilateral) and sizes were examined under pure moment loading to evaluate range of motion, adjacent-segment motion, and endplate stress.
RESULTS: Stability at the L5-S1 level decreased when smaller cages were used in both the unilateral and bilateral cage models. In the unilateral model, cage 1 (the smallest cage) resulted in 47.9% more motion at the L5-S1 level compared to cage 5 (the largest cage) in flexion, as well as 64.8% more motion in extension. Similarly, in the bilateral TLIF model, bilateral cage 1 led to 49.4% more motion at the L5-S1 level in flexion and 73.4% more motion in extension compared to bilateral cage 5. Unilateral insertion of cage 5 provided superior stability in flexion and surpassed cages 1-3 in extension when compared to cages inserted either unilaterally or bilaterally. Reduced motion at L5-S1 correlated with increased adjacent-segment motion at L4-5. Bilateral TLIF resulted in greater adjacent-segment motion compared to unilateral TLIF with the same-size cages. Inferior endplates experienced higher stress during flexion and extension than superior endplates, with this difference being more pronounced in the bilateral model. In bilateral cage placement, stress differences ranged from 46.3% to 60.0%, while they ranged from 1.1% to 9.6% in unilateral cages. Qualitative analysis revealed increased focal stress in unilateral cages versus bilateral cages.
CONCLUSIONS: The authors\' study shows that using a large unilateral TLIF cage may offer better stability than the bilateral insertion of smaller cages. While large bilateral cages increase adjacent-segment motion, they also provide a uniform stress distribution on the endplates. These findings deepen our understanding of the biomechanics of the available expandable TLIF cages.

UNASSIGNED: To summarize the research progress in the treatment of distal humeral metaphyseal-diaphyseal junction (DHMDJ) fractures in children and to provide reference for clinical practice.
UNASSIGNED: The characteristics and treatment methods of transverse and comminuted DHMDJ fractures in children were summarized and analyzed by referring to relevant literature at home and abroad.
UNASSIGNED: DHMDJ fractures in children are not uncommon clinically, with high fracture line position, multi-directional instability, difficult closed reduction in treatment, and easy to cause complications such as coronal and sagittal deformity of the elbow. The Kirschner wire technique was effective for DHMDJ fractures with the fracture line at the middle and low levels, but was prone to iatrogenic ulnar nerve injury. Elastic stable intramedullary nail is suitable for higher-position transverse DHMDJ fractures. However, this technique requires a second operation to remove the internal fixator, and may cause iatrogenic epiphysis plate injury in children. External fixator is a new way to treat DHMDJ fractures, and it can show satisfactory results for transverse and comminuted DHMDJ fractures. However, at present, there are few relevant studies, and most of them focus on biomechanical studies, and the efficacy lacks high-quality clinical research support.
UNASSIGNED: The ultimate goal of DHMDJ fracture treatment in children is to restore the anatomical alignment of the fracture and prevent the loss of reduction. The choice of internal fixator depends on the location of the fracture line and the shape of the fracture to provide personalized treatment.
UNASSIGNED: 总结儿童肱骨远端骨干-干骺端交界区（distal humeral metaphyseal-diaphyseal junction，DHMDJ）骨折治疗研究进展，为临床提供参考。.
UNASSIGNED: 广泛查阅国内外有关文献，对儿童DHMDJ横形骨折及内侧柱不稳定骨折特点及相关治疗方法进行总结分析。.
UNASSIGNED: 儿童DHMDJ骨折在临床并不少见，其骨折线位置较高，往往具有多方向不稳定性，治疗上闭合复位困难，容易引起肘关节冠状面和矢状面畸形等并发症。以往克氏针技术对于中、低位骨折疗效较好，但容易引起医源性尺神经损伤。弹性髓内钉适用于骨折线位置较高的横形骨折，然而需要二次手术取出内固定物，还可能导致医源性骺板损伤。外固定架是治疗DHMDJ骨折新方式，无论是横形骨折，还是内侧柱不稳定骨折，临床疗效均满意。然而，目前相关研究较少，多集中于生物力学研究，疗效缺少高质量临床研究支持。.
UNASSIGNED: 儿童DHMDJ骨折治疗以恢复骨折解剖对位和防止复位丢失为最终目的，内固定物选择取决于骨折线位置和骨折形态。.

OBJECTIVE: The objective of this study was to evaluate and compare the effectiveness and clinical results of trifocal bone transport (TBT) and pentafocal bone transport (PBT) in treating distal tibial defects > 6 cm resulting from posttraumatic osteomyelitis, highlighting the potential advantages and challenges of each method.
METHODS: A retrospective assessment was conducted on an overall population of 46 eligible patients with distal tibial defects > 6 cm who received treatment between January 2015 and January 2019. Propensity score analysis was used to pair 10 patients who received TBT with 10 patients who received PBT. The outcomes assessed included demographic information, external fixation time (EFT), external fixation index (EFI), bone and functional outcomes assessed using the Association for the Study and Application of the Method of Ilizarov (ASAMI) scoring system, and postoperative complications evaluated using the Paley classification.
RESULTS: The demographic and baseline data of the two groups were comparable. Following radical debridement, the average tibial defect was 7.02 ± 0.68 cm. The mean EFT was significantly shorter in the PBT group (130.9 ± 16.0 days) compared to the TBT group (297.3 ± 14.3 days). Similarly, the EFI was lower in the PBT group (20.67 ± 2.75 days/cm) than in the TBT group (35.86 ± 3.69 days/cm). Both groups exhibited satisfactory postoperative bone and functional results. Pin site infection was the most common complication and the rates were significantly different between the groups, with the PBT group demonstrating a higher incidence.
CONCLUSIONS: Both TBT and PBT effectively treat posttraumatic tibial defects greater than 6 cm, with PBT offering more efficient bone regeneration. However, PBT is associated with a higher rate of pin site infections, highlighting the importance of careful management in these complex procedures and emphasizing the need for expert surgical execution and tailored treatment approaches in orthopedic reconstructive surgery.