Bone Healing Gone Wrong: Pathological Fracture Healing and Non-Unions-Overview of Basic and Clinical Aspects and Systematic Review of Risk Factors

Comparison of Three Internal Fixation Constructs for AO/OTA 33-A3 Distal Femoral Fractures: A Biomechanical Study

BACKGROUND

To compare the biomechanical performance of three internal fixation constructs for AO/OTA 33-A3 distal femoral fractures.

METHODS

Thirty AO/OTA 33-A3 synthetic distal femoral fracture models were constructed and randomly divided into three groups. Group A (dual-plate construct) was fixed with a medial locking plate combined with a less invasive stabilization system (LISS). Group B was fixed with a retrograde femoral nail (RFN) combined with an LISS (RFN + LISS construct), and Group C was fixed with a retrograde tibial nail (RTN) combined with an LISS (RTN + LISS construct). The axial displacement, axial stiffness, torsional displacement, torsional stiffness and maximum failure load of different internal fixation constructs were recorded and statistically analyzed.

RESULTS

In the axial compression test, the average stiffness of Group C was significantly higher than that of Groups A and B, and the average displacement of Group C was significantly smaller than that of Groups A and B. In the torsion test, the torsion degree of Group C was significantly lower than that of Groups A and B, and Group C had a higher torsional stiffness than Groups A and B. In the axial compression failure test, the average ultimate load (a displacement greater than 5 mm) of Group C was significantly higher than that of Groups A and B.

CONCLUSION

The biomechanical strength of the RTN combined with a plate is higher than that of the RFN combined with plate and dual-plate constructs, which can be used as an internal fixation option for the treatment of comminuted distal femoral fractures.

Radiologic and histopathologic effects of favipiravir and hydroxychloroquine on fracture healing in rats

Fracture healing is a process in which many factors interact. In addition to many treatments, physical and biological therapy methods that affect different steps of this process, there are many biological and chemical agents that cause fracture union delay. Although the number of studies on fracture healing is increasing day by day, the mechanism of fracture healing, which is not fully understood, still attracts the attention of all researchers. In this study, we aimed to investigate the effects of favipiravir and hydroxychloroquine used in the treatment of COVID-19. In this study, 48 male Wistar rats weighing 300 ± 50 g were used. Each group was divided into eight subgroups of six rats each to be sacrificed at the 2nd and 4th weeks and evaluated radiologically and histologically. Favipiravir (group 1), hydroxychloroquine (group 2), favipiravir + hydroxychloroquine (group 3), and random control (group 4) were used. A statistically significant difference was observed between the 15th day histological scoring averages of the groups (p < 0.05). Although there was no statistically significant difference between the 15th day radiological score distributions of the groups (p > 0.05), we obtained different results in terms of complete bone union distributions and radiological images of the fracture line. Although favipiravir has a negative effect on fracture union in the early period, favipiravir may have a positive effect on fracture union in the late period. We did not find any effect of hydroxychloroquine on fracture union.

Lumbar Spinal Rahisynthesis with Plif: a Retrospective Study of 58 Patients Demonstrating Imaging and Clinical Outcomes with One Year Follow-up

BACKGROUND/OBJECTIVES

Nowadays, posterior lumbar cages remain a popular choice among the available options for interbody fusion even when compared with anterior approaches. As the posterior lumbar anatomy permits a relatively easy exposure to the spinal anatomy of interest, expandable cages prove to be a reliable tool for 360-degree fusion. Our study aspires to investigate the postoperative effects of Flarehawk 9 after open posterior lumbar fixation.

MATERIALS AND METHODS

We retrospectively analyzed 58 patients (36 males and 22 females) with a mean age of 59.8 years (age range of 33 to 79 years) who underwent open posterior lumbar fixation and decompression using Flarehawk 9 as an interbody cage between September 2021 and February 2023, with a minimum follow-up of 12 months. Patients fit for surgery and with adequate surgical indications suffered from spinal canal stenosis, failed back surgery syndrome, or in need of revision surgery, recurrent disc herniation, spondylolisthesis with mechanical back pain and adjacent segment disease.

RESULTS

Based on the Odeswery index, most of the patients who underwent posterior fixation presented a significant clinical improvement postoperatively. The rate of bony fusion can be affected by the number of fused levels and whether the patient underwent revision surgery. Our study suggested that the number of lordosis that the patients gained on average is 2±0.4 degrees.

CONCLUSIONS

The posterior lumbar approach is the golden standard of degenerative spinal surgery even compared to modern anterior approaches. Interbody cages can offer an improvement in fusion rate, lordosis and disc height. Large follow-ups are mandatory for the evaluation of each type of cage.

Nanoparticles in Bone Regeneration: A Narrative Review of Current Advances and Future Directions in Tissue Engineering

The rising demand for effective bone regeneration has underscored the limitations of traditional methods like autografts and allografts, including donor site morbidity and insufficient biological signaling. This review examines nanoparticles (NPs) in tissue engineering (TE) to address these challenges, evaluating polymers, metals, ceramics, and composites for their potential to enhance osteogenesis and angiogenesis by mimicking the extracellular matrix (ECM) nanostructure. The methods involved synthesizing and characterizing nanoparticle-based scaffoldsand integrating hydroxyapatite (HAp) with polymers to enhance mechanical properties and osteogenic potential. The results showed that these NPs significantly promote cell growth, differentiation, and bone formation, with carbon-based NPs like graphene and carbon nanotubes showing promise. NPs offer versatile, biocompatible, and customizable scaffolds that enhance drug delivery and support bone repair. Despite promising results, challenges with cytotoxicity, biodistribution, and immune responses remain. Addressing these issues through surface modifications and biocompatible molecules can improve the biocompatibility and efficacy of nanomaterials. Future research should focus on long-term in vivo studies to assess the safety and efficacy of NP-based scaffolds and explore synergistic effects with other bioactive molecules or growth factors. This review underscores the transformative potential of NPs in advancing BTE and calls for further research to optimize these technologies for clinical applications.

A Biomechanical Comparison Study of Plate-Nail and Dual-Plate Fixation in AO/OTA 41-C2 Tibial Plateau Fractures

BACKGROUND CONTEXT

This study's purpose was to evaluate the biomechanical performance of plate-nail and dual-plate fixation for the treatment of AO/OTA 41-C2 tibial plateau fractures.

METHODS

Twenty synthetic tibias were selected and randomly divided into a plate-nail group (n = 10) and a dual-plate group (n = 10). After the artificial tibias were osteotomized to simulate AO/OTA 41-C2 tibial plateau fractures in both groups, the plate-nail and the dual-plate methods, respectively, were used for fixation, and then axial compression loading, three-point bending, torsion, and axial failure tests were carried out. The data of each group were recorded and statistically analyzed.

RESULTS

In the axial compression test, the average stiffness of the plate-nail group was higher than that of the dual-plate group (p < 0.05). The displacement generated in the plate-nail group was significantly smaller than that in the dual-plate group (p < 0.05). In the resisting varus test, the stress of the plate-nail group was significantly higher than that of the dual-plate group (p < 0.05). In the resisting valgus test, the stress of the plate-nail group was slightly higher than that of the dual-plate group, but the difference was not statistically significant (p > 0.05). In the static torsion test, the load applied to the plate-nail group was smaller than that of the dual-plate group when rotated to 5° (p < 0.05). In the axial compression failure test, the average ultimate load of the plate-nail group was significantly higher than that of the dual-plate group (p < 0.05).

CONCLUSION

The treatment of AO/OTA 41-C2 tibial plateau fractures with plate-nail fixation is superior to that with dual-plate fixation in resisting axial stress and preventing tibial varus deformity, while dual-plate fixation has better resisting torsional ability.

CGRP promotes osteogenic differentiation by regulating macrophage M2 polarization through HDAC6/AKAP12 signaling pathway

Aim: To determine the mechanism of Calcitonin gene-related peptide (CGRP) in bone healing.Materials & methods: Alkaline phosphatase (ALP) activity and inflammatory-factor levels were detected using ELISA. Osteogenic differentiation was assessed using Alizarin red staining technique. The interaction between histone deacetylase 6 (HDAC6) and A-kinase anchoring protein 12 (AKAP12) was investigated through Co- immunoprecipitation.Results: CGRP treatment promoted rat bone marrow-derived macrophages (BMDMs) M2 polarization. CGRP facilitated osteogenic differentiation by enhancing M2 polarization of BMDMs. Mechanistically, CGRP promoted AKAP12 acetylation to activate the extracellular regulated protein kinases pathway by HDAC6 inhibition.Conclusion: CGRP promoted M2 polarization of rat BMDMs and facilitated osteogenic differentiation through the HDAC6/AKAP12/extracellular regulated protein kinases signaling pathway, thereby promoting bone healing.

Opioid-Sparing Nonsteroid Anti-inflammatory Drugs Protocol in Patients Undergoing Intramedullary Nailing of Tibial Shaft Fractures: A Randomized Control Trial

INTRODUCTION

Nonsteroidal anti-inflammatory drugs (NSAIDs) are effective analgesics commonly used in fracture management. Although previously associated with delayed fracture healing, multiple studies have demonstrated their safety, with minimal risks of fracture healing. Given the current opioid crisis in the United States, alternate pain control modalities are essential to reduce opioid consumption. This study aims to determine whether the combination of oral acetaminophen and intravenous ketorolac is a viable alternative to opioid-based pain management in closed tibial shaft fractures treated with intramedullary nailing.

METHODS

We conducted a randomized controlled trial evaluating postoperative pain control and opioid consumption in patients with closed tibial shaft fractures who underwent intramedullary nailing. Patients were randomized into an NSAID-based pain control group (52 patients) and an opioid-based pain control group (44 patients). Visual analog scale (VAS) scores and morphine milligram equivalents (MMEs) were evaluated at 12-hour postoperative intervals during the first 48 hours after surgery. Nonunion and delayed healing rates were recorded for both groups.

RESULTS

A statistically significant decrease in MMEs was noted at every measured interval (12, 24, 36, and 48 hours) in the NSAID group compared with the opioid group ( P -value 0.001, 0.001, 0.040, 0.024, respectively). No significant change in visual analog scale scores was observed at 12, 36, and 48 hours between both groups ( P -value 0.215, 0.12, and 0.083, respectively). A significant decrease in VAS scores was observed at the 24-hour interval in the NSAID group compared with the opioid group ( P -value 0.041). No significant differences in union rates were observed between groups ( P -value 0.820).

DISCUSSION

Using an NSAID-based postoperative pain protocol led to a decrease in opioid consumption without affecting pain scores or union rates. Owing to the minimal risk of short-term NSAID use, their role in the perioperative management of tibia shaft fractures is justified, especially when they reduce opioid consumption markedly.

LEVEL OF EVIDENCE

Therapeutic Level I.

Methods to accelerate fracture healing - a narrative review from a clinical perspective

Bone regeneration is a complex pathophysiological process determined by molecular, cellular, and biomechanical factors, including immune cells and growth factors. Fracture healing usually takes several weeks to months, during which patients are frequently immobilized and unable to work. As immobilization is associated with negative health and socioeconomic effects, it would be desirable if fracture healing could be accelerated and the healing time shortened. However, interventions for this purpose are not yet part of current clinical treatment guidelines, and there has never been a comprehensive review specifically on this topic. Therefore, this narrative review provides an overview of the available clinical evidence on methods that accelerate fracture healing, with a focus on clinical applicability in healthy patients without bone disease. The most promising methods identified are the application of axial micromovement, electromagnetic stimulation with electromagnetic fields and direct electric currents, as well as the administration of growth factors and parathyroid hormone. Some interventions have been shown to reduce the healing time by up to 20 to 30%, potentially equivalent to several weeks. As a combination of methods could decrease the healing time even further than one method alone, especially if their mechanisms of action differ, clinical studies in human patients are needed to assess the individual and combined effects on healing progress. Studies are also necessary to determine the ideal settings for the interventions, i.e., optimal frequencies, intensities, and exposure times throughout the separate healing phases. More clinical research is also desirable to create an evidence base for clinical guidelines. To make it easier to conduct these investigations, the development of new methods that allow better quantification of fracture-healing progress and speed in human patients is needed.

Three-year follow-up of the grip concept: an open, prospective, observational registry study on biomechanically calculated abdominal wall repair for complex incisional hernias

PURPOSE

We studied the effectiveness of biomechanically calculated abdominal wall reconstructions for incisional hernias of varying complexity in an open, prospective observational registry trial.

METHODS

From July 1st, 2017 to December 31st, 2020, four hospitals affiliated with the University of Heidelberg recruited 198 patients with complex incisional hernias. Hernias were repaired using biomechanically calculated reconstructions and materials classified on their gripping force towards cyclic load. This approach determines the required strength preoperatively based on the hernia size, using the Critical Resistance to Impacts related to Pressure. The surgeon is supported in reliably determining the Gained Resistance, which is based on the mesh-defect-area-ratio, as well as other mesh and suture factors, and the tissue stability. Tissue stability is defined as a maximum distension of 1.5 cm upon a Valsalva maneuver. In complex cases, a CT scan of the abdomen can be used to assess unstable tissue areas both at rest and during Valsalva's maneuver.

RESULTS

Larger and stronger gripping meshes were required for more complex cases to achieve a durable repair, especially for larger hernia sizes. To achieve durable repairs, the number of fixation points increased while the mesh-defect area ratio decreased. Performing these repairs required more operating room time. The complication rate remained low. Less than 1% of recurrences and low pain levels were observed after 3 years.

CONCLUSIONS

Biomechanical stability, defined as the resistance to cyclic load, is crucial in preventing postoperative complications, including recurrences and chronic pain.

Lower Extremity Open Fractures Fix and Flap: Does Initial Management in Non-specialized Hospitals Really Compromise its Outcome?

Introduction Managing open lower extremity fractures is challenging, with potential complications such as amputation and infection. The aim of the study was to determine whether the time delay and initial treatment of the patients treated in a non-specialized hospital before being transferred to a dedicated level I trauma center led to a worse outcome. Methods Retrospective data from 44 patients (37 males and seven females) undergoing free tissue transfer for lower extremity open fractures from January 2017 to December 2022 were analyzed. Group A received primary care externally and was later transferred for definitive treatment (n=17, 38.6%), while group B received initial care at a level I trauma center (n=27, 61.4%). Surgical outcomes, complications, the duration of the hospital stay, and assessment times were compared. Various demographic variables, co-morbidities, prior interventions, and flap types were analyzed.  Results Average age (A: 55.1±16.7; B: 38.7±19.8 years; p=0.041), overall hospitalization (A: 55.7±22.8; B: 42.8±21.3 days; p=0.041), and time to soft tissue reconstruction differed significantly between groups (A: 30.7±12.2; B: 18.9±9.3 days; p=0.013). Overall, 31.8% had multiple injuries without statistical differences between groups A and B (29.4% vs. 33.3%; p>0.05). There were no statistical differences between the groups in terms of major and minor complications and bone healing characteristics. Limb salvage was successful overall in 93.2% (A: 94.1%; B: 92.6%; P>0.05). Major complications occurred in 9.1%; three patients underwent major amputation (A: n=2; B: n=1). Minor complications were observed in 43.2% of patients (partial flap necrosis, wound dehiscence and non-union; A: 41.2%; B: 44.4%; p>0.05). Overall, 65.9% of patients (A: 64.7%; B: 66.7%; p>0.05) experienced uneventful bone healing, while 18.2% of patients (A: 23.5%; B: 14.8%; p>0.05) experienced delayed healing. Flaps used were mostly musculocutaneous (71.7%). Various assessed demographic characteristics, including age and presence of polytrauma, showed no significant influence on complications (p>0.05). Conclusion  Although there is a significant difference in the time course of externally treated patients with open fractures, prolonged treatment is not associated with a higher complication rate or compromised bone healing outcome. Despite the findings, it is important to avoid delays and strive for interdisciplinary collaboration.

Cigarette smoke and nicotine effect on human mesenchymal stromal cell wound healing and osteogenic differentiation capacity

INTRODUCTION

Mesenchymal stromal cells (MSCs) play a crucial role in promoting tissue regeneration and healing, particularly in bone tissue. Both smoking and nicotine use are known to delay and inhibit the healing process in patients. This study aims at delineating these cellular effects by comparing the impact of nicotine alone to cigarette smoke with equivalent nicotine content, and shedding light on potential differences in the healing process.

METHODS

We examined how cigarette smoke and nicotine affect the migration, proliferation, and osteogenic differentiation of human patient-derived MSCs in vitro, as well as the secretion of cytokines IL-6 and IL-8. We measured nicotine concentration of the cigarette smoke extract (CSE) to clarify the role of the nicotine in the effect of the cigarette smoke.

RESULTS

MSCs exposed to nicotine-concentration-standardized CSE exhibited impaired wound healing capability, and at high concentrations, increased cell death. At lower concentrations, CSE dose-dependently impaired migration, proliferation, and osteogenic differentiation, and increased IL-8 secretion. Nicotine impaired proliferation and decreased PINP secretion. While there was a trend for elevated IL-6 levels by nicotine in undifferentiated MSCs, these changes were not statistically significant. Exposure of MSCs to equivalent concentrations of nicotine consistently elicited stronger responses by CSE and had a more pronounced effect on all studied parameters. Our results suggest that the direct effect of cigarette smoke on MSCs contributes to impaired MSC function, that adds to the nicotine effects.

CONCLUSIONS

Cigarette smoke extract reduced the migration, proliferation, and osteogenic differentiation in MSCs in vitro, while nicotine alone reduced proliferation. Cigarette smoke impairs the osteogenic and regenerative ability of MSCs in a direct cytotoxic manner. Cytotoxic effect of nicotine alone impairs regenerative ability of MSCs, but it only partly explains cytotoxic effects of cigarette smoke. Direct effect of cigarette smoke, and partly nicotine, on MSCs could contribute to the smoking-related negative impact on long-term bone health, especially in bone healing.

Long-term continuous instrumented insole-based gait analyses in daily life have advantages over longitudinal gait analyses in the lab to monitor healing of tibial fractures

Introduction: Monitoring changes in gait during rehabilitation allows early detection of complications. Laboratory-based gait analyses proved valuable for longitudinal monitoring of lower leg fracture healing. However, continuous gait data recorded in the daily life may be superior due to a higher temporal resolution and differences in behavior. In this study, ground reaction force-based gait data of instrumented insoles from longitudinal intermittent laboratory assessments were compared to monitoring in daily life. Methods: Straight walking data of patients were collected during clinical visits and in between those visits the instrumented insoles recorded all stepping activities of the patients during daily life. Results: Out of 16 patients, due to technical and compliance issues, only six delivered sufficient datasets of about 12 weeks. Stance duration was longer (p = 0.004) and gait was more asymmetric during daily life (asymmetry of maximal force p < 0.001, loading slope p = 0.001, unloading slope p < 0.001, stance duration p < 0.001). Discussion: The differences between the laboratory assessments and the daily-life monitoring could be caused by a different and more diverse behavior during daily life. The daily life gait parameters significantly improved over time with union. One of the patients developed an infected non-union and showed worsening of force-related gait parameters, which was earlier detectable in the continuous daily life gait data compared to the lab data. Therefore, continuous gait monitoring in the daily life has potential to detect healing problems early on. Continuous monitoring with instrumented insoles has advantages once technical and compliance problems are solved.

Advances in Fracture Healing Research

Despite a constant refinement of surgical techniques and bone fixation methods, up to 15% of fractures result in impaired healing or even develop a non-union [...].

Bone repair and key signalling pathways for cell-based bone regenerative therapy: A review

Advances in cell-based regenerative therapy create new opportunities for the treatment of bone-related disorders and injuries, by improving the reparative phase of bone healing. Apart from the classical approach of bone grafting, the application of cell-based therapies, particularly stem cells (SCs), has gained a lot of attention in recent years. SCs play an important role in regenerative therapy due to their excellent ability to differentiate into bone-forming cells. Regeneration of new bone is regulated by a wide variety of signalling molecules and intracellular networks, which are responsible for coordinating cellular processes. The activated signalling cascade is significantly involved in cell survival, proliferation, apoptosis, and interaction with the microenvironment and other types of cells within the healing site. Despite the increasing evidence from studies conducted on signalling pathways associated with bone formation, the exact mechanism involved in controlling the differentiation stage of transplanted cells is not well understood. Identifying the key activated pathways involved in bone regeneration may allow for precise manipulation of the relevant signalling molecules within the progenitor cell population to accelerate the healing process. The in-depth knowledge of molecular mechanisms would be advantageous in improving the efficiency of personalised medicine and targeted therapy in regenerative medicine. In this review, we briefly introduce the theory of bone repair mechanism and bone tissue engineering followed by an overview of relevant signalling pathways that have been identified to play an important role in cell-based bone regenerative therapy.

Arthroscopic Scaphotrapeziotrapezoid Joint Fusion for Osteoarthritis

Background: Arthroscopic scaphotrapeziotrapezoid (STT) fusion (ASTTF) has emerged in the recent decade as an option for traditional open surgery. This retrospective study describes our technique and results of ASTTF. Methods: Medical records and radiological data of patient who had undergone ASTTF between 2014 and 2022 in two tertiary hospitals were reviewed. Results: Five ASTTF in four patients were identified. The mean age of the patients were 52.4 years. Fusion was achieved in four out of five wrists (80%). The mean postoperative radio-scaphoid angle was 48°, grip 32 kg (70% compared to contralateral hand), extension 54° (86%) and flexion 46° (93%). The mean follow-up time was 18 months (range 5 months to 4 years). One wrist (20%) developed STT non-union requiring a reoperation 2 years after index surgery. Conclusions: ASTTF is a technically challenging procedure with a long learning curve and surgery time. However, ASTTF is less invasive compared to the open procedure and our results were like the open procedures described in literature. Further studies are needed to compare the benefits and results of open and ASTTF in a prospective and randomised setup. Level of Evidence: Level IV (Therapeutic).

Peptide derived from stromal cell-derived factor 1δ enhances the in vitro expression of osteogenic proteins via bone marrow stromal cell differentiation and promotes bone formation in in vivo models

Mesenchymal stem cells (MSCs) rely on chemokines and chemokine receptors to execute their biological and physiological functions. Stromal cell-derived factor-1 (SDF-1) is upregulated in injury sites, where it acts as a chemotactic agent, attracting CXCR4-expressing MSCs, which play a pivotal role in the healing and regeneration of tissue throughout the body. Furthermore, SDF-1 expression has been observed in regions experiencing inflammation-induced bone destruction and fracture sites. In this study, we identified a novel peptide called bone-forming peptide-5 (BFP-5), derived from SDF-1δ, which can promote the osteogenesis of MSCs as well as bone formation and healing. Multipotent bone marrow stromal cells treated with BFP-5 showed enhanced alizarin red S staining and higher alkaline phosphatase (ALP) activity. Moreover, ALP and osterix proteins were more abundantly expressed when cells were treated with BFP-5 than SDF-1α. Histology and microcomputed tomography data at 12 weeks demonstrated that both rabbit and goat models transplanted with polycaprolactone (PCL) scaffolds coated with BFP-5 showed significantly greater bone formation than animals transplanted with PCL scaffolds alone. These findings suggest that BFP-5 could be useful in the development of related therapies for conditions associated with bones.

Metabolic regulation by biomaterials in osteoblast

The repair of bone defects resulting from high-energy trauma, infection, or pathological fracture remains a challenge in the field of medicine. The development of biomaterials involved in the metabolic regulation provides a promising solution to this problem and has emerged as a prominent research area in regenerative engineering. While recent research on cell metabolism has advanced our knowledge of metabolic regulation in bone regeneration, the extent to which materials affect intracellular metabolic remains unclear. This review provides a detailed discussion of the mechanisms of bone regeneration, an overview of metabolic regulation in bone regeneration in osteoblasts and biomaterials involved in the metabolic regulation for bone regeneration. Furthermore, it introduces how materials, such as promoting favorable physicochemical characteristics (e.g., bioactivity, appropriate porosity, and superior mechanical properties), incorporating external stimuli (e.g., photothermal, electrical, and magnetic stimulation), and delivering metabolic regulators (e.g., metal ions, bioactive molecules like drugs and peptides, and regulatory metabolites such as alpha ketoglutarate), can affect cell metabolism and lead to changes of cell state. Considering the growing interests in cell metabolic regulation, advanced materials have the potential to help a larger population in overcoming bone defects.