The influence of biomechanical stability on bone healing and fracture-related infection: the legacy of Stephan Perren

Mechanical study of the safe distance between humerus shaft fracture and distal locking screws in antegrade nailing

BACKGROUND

Optimal positioning of distal locking screws in intramedullary humeral nailing remains uncertain, particularly the influence of the distance between the fracture plane and the proximal distal locking screw on construct stability. This study aims to evaluate the mechanical stability of humeral nailing under different fracture-to-screw distances and numbers of distal locking screws using finite element analysis and mechanical testing on bone models.

METHODS

A finite element model and mechanical testing on six sawbones models were performed under traction (500 N), compression (500 N), and torsion (3 Nm). Models were tested with two osteotomy distances from the proximal distal locking screw (2 cm and 5 cm) and with either one or two distal locking screws. Axial and torsional stiffness and fracture displacement were recorded and analyzed statistically.

RESULTS

Finite element analysis showed higher stress concentrations near the distal fracture fragment. Mechanical testing demonstrated that traction and torsional stability were significantly affected by fracture-to-screw distance (p = 0.006 and p = 0.015), while compression stability was influenced by the number of distal screws (p = 0.035).

CONCLUSION

A fracture-to-screw distance of 5 cm was associated with improved axial and torsional stability, while double distal screws enhanced compressive stiffness. These biomechanical results, although very promising, should be confirmed with clinical studies.

A Comparison of Generic and Subject-Specific Finite Element Models of Distal Femur Fractures Treated With Locking Plates

While the need for employing subject-specific computational biomechanics models for treatment planning in orthopaedics is being increasingly voiced, it has not been clear when such specificity is essential and for which questions simpler models might be adequate. This study uses a novel modelling approach to generate finite element models to examine the influence of subject-specificity in the treatment of distal femur fractures. Three subject-specific finite element models are created from clinical CT scans, and the proposed approach is employed to impose identical fractures and locking plate treatments upon them. Additionally, the performance of the generic two-material model based on a Sawbones fourth generation femur is also evaluated. Interfragmentary motions, plate stresses, and strains at the screw-bone interface are examined due to a physiological loading at different stages of healing. The study finds that subject-specificity has a major effect on strains in the bone at the screw-bone interface. However, interfragmentary motions at the far cortex and plate stresses show minimal sensitivity to subject-specific factors, while near-cortical and shear interfragmentary motions are influenced by them. The influence of subject-specificity decreases as healing progresses. These results indicate that while generic approaches may be sufficient to calculate global assembly responses, material heterogeneity and subject-specific bone stock variations have a large impact on the interaction between the screws and bone. The study also shows that the proposed method, which enables manipulating bone geometry while retaining subject-specific properties, can be used to evaluate the influence of subject-specificity for other orthopaedic simulations.

"Anti-Bios": Can Local Antibiotics Affect Bone Union in Infected Bone Defects Treated with Degradable Bone Substitutes

Background: Segmental bone defects (SBDs) pose significant clinical challenges, often requiring complex reconstructive procedures. Degradable bone substitutes loaded with antibiotics have emerged as promising tools for infection control. However, their impact on bone healing remains uncertain. This study investigates antibiotic-loaded biodegradable scaffolds in infected defects using an in vivo rabbit model. Methods: Thirty New Zealand white rabbits were divided into three groups-antibiotic-loaded GreenBone scaffolds, non-loaded GreenBone scaffolds, and allografts. A critical-size femoral defect was surgically created and inoculated with Staphylococcus epidermidis. Radiographic evaluations were performed over 16 weeks, followed by histological and microbiological analyses. Bone union, infection rates, and callus maturation were assessed. Results: Eight rabbits were excluded for technical errors. Bone union was significantly lower in the antibiotic-loaded group (two rabbits out of seven; 28.6%) compared to the non-loaded scaffold (13 rabbits out of 15; 86.7%; p = 0.006). The antibiotic-loaded group exhibited a higher incidence of chronic osteomyelitis (100%) versus non-loaded implants (60%; p < 0.05). Histological evaluation revealed delayed bone maturation in the antibiotic-loaded group (22.2% HOES grade 3) compared to non-loaded scaffolds (69.5%; p < 0.001). Conclusions: Despite their infection-fighting potential, antibiotic-loaded biodegradable scaffolds may impair bone healing, leading to higher non-union rates and delayed maturation. These findings highlight a critical trade-off between local antibiotic therapy and bone regeneration, warranting careful clinical consideration and further research to optimize treatment strategies for infected bone defects.

The Recent Developments of Thermomechanical Processing for Biomedical Mg Alloys and Their Clinical Applications

Magnesium (Mg) alloys have gained much attention for biomedical applications, due to their attractive properties, such as high specific strength, low density, low elasticity modulus, high damping capacity, biodegradation, and relatively good cytocompatibility. However, the biomedical use of Mg alloys also faces several challenges, primarily due to their low corrosion resistance and insufficient strength. Therefore, improving the strength and corrosion resistance of biomedical Mg alloys has become a critical issue. This review briefly summarizes the selection of appropriate alloying elements for biomedical Mg alloys, which is the fundamental factor in determining their microstructure, cytocompatibility, mechanical properties, and corrosion performance. It also discusses typical thermomechanical processing methods, including hot extrusion, hot rolling and hot forging, and examines the influence of deformation mode on microstructure, mechanical properties, and degradation behavior. Specifically, combining different thermomechanical processing methods could be an optimal choice, as it leverages the high efficiency and effectiveness of each method. Finally, the clinical application of biomedical Mg alloys in various fields are summarized and discussed to highlight their potential prospect and corresponding challenges. This review aims to provide insights for the rationale design and development of high-performance biomedical Mg alloys for widespread clinical applications.

Biomechanical evaluation of composite reduction plates with variable positioning using the Henry and Thompson approaches for transverse radial fracture surgery

BACKGROUND

Radius fractures are challenging to stabilize due to complex muscle-loading conditions, requiring optimized plate positioning and material selection for effective treatment. This study addresses the biomechanical impact of plate positions (anterior, posterior, lateral) and materials in transverse radial fractures.

HYPOTHESIS

Plate positioning and material selection significantly influence stress distribution and displacement, with lateral positioning and WE43 alloy offering biomechanical advantages.

METHODS

Finite element analysis was used to evaluate Ti6Al4V titanium alloy and WE43 magnesium alloy bone plates positioned on the anterior, posterior, and lateral sides of the radius under a 50 N axial load. Stress distribution and displacement were analyzed.

RESULTS

Posterior reductions exhibited the highest stress and displacement, indicating potential instability, with maximum von Mises stress increasing by 32.5% compared to anterior reduction. Lateral reductions provided more uniform stress distribution and lower displacement, though von Mises stress was still 20% higher than in the anterior reduction. WE43 alloy demonstrated effective stress reduction in non-posterior positions, while Ti6Al4V exhibited greater stiffness and resistance to deformation.

DISCUSSION

Lateral and anterior plate positions demonstrated superior biomechanical stability, suggesting their preference for optimizing fracture healing and reducing complications. WE43 alloy's stress-reducing and biodegradable properties make it suitable for temporary fixation, while Ti6Al4V provides greater structural integrity for long-term support. These findings highlight the importance of plate positioning and material selection in improving clinical outcomes for transverse radial fracture fixation.

LEVEL OF EVIDENCE

V; expert opinion, controlled laboratory study.

Fracture-Related Infections

Fracture-related infections are challenging complications in orthopedic care, marked by infection at fracture or surgical sites, often involving biofilm-associated pathogens. They result in significant morbidity, prolonged hospitalizations, and high health care costs. Diagnosis integrates clinical, laboratory, and imaging findings, while treatment combines surgical debridement, implant management, and targeted antimicrobial therapy. Common pathogens include Staphylococcus aureus and Staphylococcus epidermidis, with culture-negative cases requiring advanced diagnostics. A multidisciplinary approach is critical to optimizing outcomes, addressing complications, and reducing the socioeconomic impact of these infections. Advances in treatment strategies continue to improve survival and quality of life for affected patients.

Impact of fracture morphology on the biomechanical stability of osteosynthetic fixation

Biomechanical testing is essential for evaluating osteosyntheses, particularly in assessing stability, stiffness, and fragment motion. However, traditional flat-fracture models created via osteotomy fail to replicate the complex morphology of real-world fractures, potentially reducing the applicability of results. This study introduces patient-specific distal femur fracture models to investigate the impact of fracture morphology on the biomechanical performance of osteosyntheses. Realistic fracture models were generated using 3D printing and molding, based on CT-derived geometry, alongside traditional osteotomy models. Four groups were tested: osteotomized and realistic fracture models, with and without gaps. All constructs were treated with distal femur locking plates and subjected to axial and torsional loading. Dynamic testing simulated physiological conditions and tracked interfragmentary motions with a 3D optical motion system. Realistic fracture models exhibited higher torsional stiffness and reduced interfragmentary motion compared to osteotomized models, particularly in closed fracture gaps. Axial stiffness increased significantly upon fracture gap closure in all gap groups, transitioning from exclusively plate-bearing to construct-bearing configurations. The irregular geometry of realistic fractures provided enhanced interlocking, improving stability under both axial and torsional loads. Patient-specific fracture models better replicate the mechanical behaviour of clinical distal femur fractures, demonstrating advantages over osteotomized fracture models. The inclusion of realistic fracture geometries in biomechanical testing improves the transfer of biomechanical results into a clinical setting and offers valuable insights for optimizing designs and improving clinical outcomes.

Engineering the bone reconstruction surgery: the case of the masquelet-induced membrane technique

The reconstruction of large bone defects remains challenging for orthopedic surgeons. Autologous bone grafts (ABGs) are the gold standard treatment for limited size defects, but larger bone defects (> 5 cm) require the use of more sophisticated techniques, such as the Masquelet technique. Over the last three decades, the Masquelet or induced membrane technique (IMT) has become increasingly popular as it does not require high-precision microsurgery skills and the time taken to achieve bone consolidation is independent of the length of the defect. IMT is a two-stage procedure. In the first stage, a polymethylmethacrylate (PMMA) cement spacer is implanted into the bone lesion and a physiological immune reaction initiates the formation of a fibrotic induced membrane (IM) with both angiogenic and osteogenic properties. The second stage, performed several weeks later, involves removal of the spacer followed by the implantation of a standard ABG in the preserved IM cavity for subsequent bone repair. In this extensive review, we explain how the success of this surgical procedure can be attributed to the synergy of four key components: the inducer (the PMMA cement), the recipient (the IM), the effector (the bone graft) and the modulator (the mechanical environment). Conversely, we then explain how each key component can contribute to the failure of such treatment. Finally, we discuss existing or emerging innovative and biotechnology-oriented strategies for optimizing surgical outcome with respect to the four components of IMT described above.

Introducing the Pearl-String Technique: A New Concept in the Treatment of Large Bone Defects

The reconstruction of long bone defects after the primary traumatic, secondary infectious, or tumor-related loss of substance continues to represent a surgical challenge. Distraction osteogenesis using segmental transport, vascularized bone transfer, and the induced membrane technique (IMT) are established methods of reconstruction. IMT has become increasingly popular in recent decades due to its practicability, reproducibility, and reliability. At the same time, the original technique has undergone numerous modifications. The results are correspondingly heterogeneous. This article is intended to provide an overview of the current principles and modifications of IMT, outline the causes of failure of the IMT, and introduce the pearl-string technique (PST). The PST developed in our hospital is based on the pearl-string-like arrangement of thermodisinfected, decorticated femoral heads (TDFHs) in combination with a mechanically stable osteosynthetic construct. The TDFHs are biologically activated with either an RIA or autologous iliac crest bone graft. To gain a better understanding of these variations, the surgical technique of both procedures is illustrated step-by-step in this article.

Posterior fixation without debridement for pyogenic spondylodiscitis can promote infection control: initial evaluation of a pyogenic spondylodiscitis posterior fixation rat model

PURPOSE

Pyogenic spondylodiscitis is a significant health concern, particularly in older individuals. Minimally invasive surgical techniques, such as posterior fixation, are promising for infection control; however, their mechanisms remain unclear. This study aimed to clarify how posterior fixation promotes infection control in an animal model.

METHODS

Thirty female Wistar rats were used to create a pyogenic spondylodiscitis model by injecting methicillin-sensitive Staphylococcus aureus into the intervertebral space between the 6th and 7th coccygeal vertebrae. Three days post-injection, rats were divided into fixation and control groups. The fixation group underwent posterior fixation with an external fixator, whereas the control group underwent screw insertion alone. Bone destruction was assessed via microcomputed tomography on postoperative days (POD) 7, 14, and 21. Immunohistochemistry for cathepsin K and receptor activator of nuclear factor-kappa B ligand (RANKL) was performed on POD 7 samples to assess osteoclast activity.

RESULTS

The fixation group showed less bone destruction than the control group at POD 14 (35% vs. 56%, p = 0.0007) and POD 21 (30% vs. 52%, p < 0.0001). The cathepsin K-positive area was significantly reduced in the fixation group (p = 0.027). RANKL expression was localized within the intervertebral disc in the fixation group, whereas RANKL was strongly expressed on the bone surface adjacent to the disc in control. The RANKL-positive area was also reduced in the fixation group (p = 0.041).

CONCLUSIONS

Our combined model of pyogenic spondylodiscitis and posterior fixation supports the theory that posterior fixation stability suppresses RANKL and osteoclast expression, promoting infection control.

Timing in orthopaedic surgery - Rethinking traditional myths with a critical perspective

PURPOSE

Standard operating procedures aim to achieve a standardized and assumedly high-quality therapy. However, in orthopaedic surgery, the aspect of temporal urgency is often based on surgical tradition and experience. At a time of evidence-based medicine, it is necessary to question these temporal guidelines. The following review will therefore address the most important temporal guidelines in orthopaedic surgery and discuss their practical relevance and potential need for optimization.

METHODS

The systematic review features a literature review by database search in "PubMed" (https://pubmed.ncbi.nlm.nih.gov) for time to surgery in terms of (1) "proximal femoral fractures", (2) "femoral neck fractures", (3) "proximal humeral fractures", (4) "ligament and tendon injuries", (5) "spinal cord injuries", (6) "open fractures" and (7) "fracture-related infections". For every diagnosis, hypotheses on timing were set up and checked for evidence.

RESULTS

There is solid clinical evidence supporting the initiation of treatment within 24 h for specific conditions like the surgical treatment of proximal femur fractures and prompt decompression of spinal cord injuries. However, for other scenarios such as the 6-hour rule for open fractures, joint-preserving femoral neck fractures, timing of ligament injuries, humeral head fractures and fracture-related infections there is currently no reliable evidence to guide prompt surgical treatment.

CONCLUSION

Based on the current data, resource-adapted surgical planning seems reasonable. Further research in these areas is necessary to determine the best timing of treatment and address existing doubts.

Are high cutibacterium bacterial loads at the time of revision shoulder arthroplasty associated with more severe clinical signs or symptoms or increased risk of recurrent periprosthetic joint infection?

PURPOSE

Cutibacterium is commonly isolated from deep tissue samples taken at the time of revision shoulder arthroplasty, but the significance of these positive cultures is debated, and the impact of increasing bacterial loads on clinical outcomes is unclear. The objectives of this study were to (1) identify factors independently associated with high bacterial loads, and (2) compare patient-reported outcomes (PROs) and revision rates in patients found to have high Cutibacterium loads.

MATERIALS AND METHODS

Male patients undergoing single stage exchange with a minimum 2-year follow-up were included. Culture data were semi-quantitatively scored with the total Cutibacterium score (TShCuS). Two groups were compared: patients with a High Cutibacterium Load (HCL) group and those with Low Cutibacterium Load (LCL) group. PROs and revision rates were compared, and a multivariable analysis was conducted.

RESULTS

Of 68 male patients that underwent revision shoulder arthroplasty, 29 (42.6%) met the inclusion criteria for the HCL group, while 27 patients (39.7%) were in the LCL group. Mean follow-up was 4.7 ± 3 years. Patients with intraoperative humeral loosening had an 18.4 times increased risk of having high Cutibacterium loads (95% CI 2.1-154.4, p < 0.001). There were no significant differences in PROs or re-revision rates between the HCL and LCL groups.

CONCLUSIONS

Intraoperative humeral loosening was independently associated with high Cutibacterium loads found at the time of revision shoulder arthroplasty. Male patients with high bacterial loads treated with complete single stage exchange and antibiotics had patient-reported outcomes similar to those of patients with minimal to no load.

LEVEL OF EVIDENCE

III.

The Role of Spinal Instability in Treating Unstable Infected Fractures

Vertebral (spinal) osteomyelitis is a rare spinal infection of the vertebral column that can be caused by bacteria or fungi. Though the initial treatment for all patients with vertebral osteomyelitis consists of antibiotics, surgery can be indicated in certain cases, such as in the presence of spinal instability or when antibiotics are not successfully eliminating the infection. Achieving spinal stability can be an important component of treating fracture-related infections, as instability can cause local damage and disrupt the healing process. The authors present the case of a patient with vertebral osteomyelitis that was not resolving with the administration of antibiotics in the context of a spinal fracture. A minimally invasive surgery was performed to achieve spinal stability and the infection soon resolved with antibiotics.

Can we DAIR in FRI ? Debridement techniques in osteomyelitis

The concept of Debridement, Antibiotics and Implant Retention (DAIR) is well known in periprosthetic joint infections. Extrapolating this concept to fracture related infections is mired in controversies. Characteristics of the metal implant, duration of infection, state of fracture healing, microbiological profile etc. appear to play a role in the decision making process whether or not to keep, adjust , exchange or remove (infected) metalwork. More than likely it is the quality of source control by meticulous debridement having a major impact whether a DAIR approach to FRI could result in a successful outcome.

The Impact of Early Axial Interfragmentary Motion on the Fracture Healing Environment: A Scoping Review

PURPOSE

The initial interfragmentary motion (IFM) at a fracture site determines the mode of fracture healing. Understanding the impact of orthopaedic interventions on the fracture environment is essential to advancing our knowledge of fracture healing. The purpose of this scoping review is to analyze the orthopaedic literature to assess our understanding of the effects of early axial IFM on fracture healing outcomes.

METHODS

PubMed, OVID, and Scopus databases were queried to identify all studies from inception until June 2023 assessing axial IFM on fracture healing outcomes in animal and human subjects. We collected information regarding the amount of IFM, osteotomy/fracture location, experimental methodology, and outcomes (histologic, biomechanical, and radiographic evidence of fracture healing) for each study. Data synthesis is presented as a narrative review of our findings.

RESULTS

In total, 4,972 studies were identified. Fifteen studies were included, totaling 605 fractures/osteotomies. Of the included studies, 423 animal and 182 human subjects were examined. Nine studies investigated IFM at the tibia, four at the metatarsus, and two at the femur. The median time to analysis was nine weeks. The fracture gap size did not exceed 6 mm in any study. The range of IFM in tibias, metatarsi, and femurs was 0.3-2.0 mm, 0.1-2.4 mm, and 0.03-1.0 mm, respectively. No experiment using a femur model identified an association between early axial IFM and healing outcomes. All studies at the level of the tibia exhibited positive effects on callus formation with small-to-moderate axial IFM (mean 0.54, SD 0.30; range 0.2-0.9 mm). Most studies (9/13, 69.2%) found that early micromovement produced superior stiffness and biomechanical rigidity at the fracture site compared to absolute stability. While larger IFMs (mean 1.28, SD 0.70; range 0.25-2.4 mm) frequently led to a larger callus area, the callus quality and biomechanical strength of the callus was compromised.

CONCLUSION

The definitive range of axial IFM conducive to a favorable healing environment remains elusive. However, preliminary evidence suggests an association between small-to-moderate (mean 0.41, SD 0.32; range: 0.03- 1.0 mm) initial axial IFM for stimulating successful fracture healing. This review found that the cumulative evidence present in the literature is insufficient to determine a definite correlation between the early axial IFM and outcomes.

Effect of mechanical stability of osteosynthesis on infection rates: Timing of temporary and definitive fixation

Fracture related infection (FRI) remains one of the most challenging complications of orthopaedic trauma surgery. Several factors contribute to FRI development but, among those, particularly interesting from the orthopaedic surgeon's perspective is the contribution of mechanical stability and timing of fracture fixation. These are indeed crucial factors both in prevention and treatment of FRI and are directly influenced by the surgeon's work. While the role of stability has been studied and discussed, the pathophysiological process regulating such role and how this influences surgeon's treatment decision making is still debated. The same applies to the ideal timing of temporary or definitive fixation which varies according to the clinical scenario considered. In the present narrative review, we described the influence of mechanical stability on both FRI pathophysiology and on the decision making of FRI treatment. In addition, we analysed the impact of the timing of fracture fixation on the risk of FRI development particularly in those clinical scenarios where it has been shown to be specifically relevant, such as fractures affecting segments with poor soft tissue envelope, open fractures, damage control orthopaedics, and the need for soft tissue coverage.

Multidisciplinary approach and host optimization for fracture-related infection management

In orthopaedic trauma, fracture-related infections (FRI) are still dreadful challenges that can cause non-union, amputation and even death. Standardization of general treatment strategies for FRI is still lacking. Due to the complexity of FRI, a multidisciplinary approach addressing host status, state of the fracture and causative microorganism has been applied in the management of FRI. Surgical treatment, antibiotic therapy and host optimization for FRI were summarized and discussed. The goal of this review is to provide an overview and summary of current approaches of FRI management and to make suggestions on FRI prevention and treatment based on multidisciplinary principles.

The FRI classification - A new classification of fracture-related infections

AIM

To identify the most relevant factors with respect to the management of fracture-related infection (FRI) and to develop a comprehensive FRI classification that guides decision-making and allows scientific comparison.

METHOD

An international group of FRI experts determined the preconditions, purpose, primary factors for inclusion, format and detailed description of the elements of an FRI classification through a consensus driven process.

RESULTS

Three major elements were identified and grouped together in the FRI Classification: Fracture (F), Related patient factors (R) and Impairment of soft tissues (I). Each element was divided into five levels of complexity. Fractures can be healed (F1) or unhealed (F2-5). Patients may be fully healthy (R1) or have 4 levels of compromise, with and without end-organ damage (R2-5). Soft tissue condition ranges from well vascularized and easily closed (I1) to major skin defects requiring free flaps (I4). In all three elements, the fifth level (F5, R5 or I5) describes a patient who has an unreconstructible bone, soft tissue envelope or is not fit for surgery.

CONCLUSION

The FRI classification, which is based on the three major elements Fracture (F), Related patient factors (R) and Impairment of soft tissues (I) is intended to guide decision-making and improve the quality of scientific reporting for FRIs in the future. The proposed classification is based on expert opinion and therefore an essential next step is clinical validation, in order to realize the ultimate goal of improving outcomes in the management of FRI.

Comment on permeability conditions in finite element simulation of bone fracture healing

The most popular model of the bone healing considers the fracture callus as poroelastic medium. As such it requires an assumption of the callus' external permeability. In this work a systematic study of the influence of the permeability of the callus boundary on the simulated bone healing progress is performed. The results show, that these conditions starts to play significant role with the decrease of the callus size. Typically enforced impermeability inhibits the progress of healing during simulation. A remedy for this effect is imposing drainage conditions at the callus' boundary.

Mechanobiology of bacterial biofilms: Implications for orthopedic infection

Postoperative bacterial infections are prevalent complications in both human and veterinary orthopedic surgery, particularly when a biofilm develops. These infections often result in delayed healing, early revision, permanent functional loss, and, in severe cases, amputation. The diagnosis and treatment pose significant challenges, and bacterial biofilm further amplifies the therapeutic difficulty as it confers protection against the host immune system and against antibiotics which are usually administered as a first-line therapeutic option. However, the inappropriate use of antibiotics has led to the emergence of numerous multidrug-resistant organisms, which largely compromise the already imperfect treatment efficiency. In this context, the study of bacterial biofilm formation allows to better target antibiotic use and to evaluate alternative therapeutic strategies. Exploration of the roles played by mechanical factors on biofilm development is of particular interest, especially because cartilage and bone tissues are reactive environments that are subjected to mechanical load. This review delves into the current landscape of biofilm mechanobiology, exploring the role of mechanical factors on biofilm development through a multiscale prism starting from bacterial microscopic scale to reach biofilm mesoscopic size and finally the macroscopic scale of the fracture site or bone-implant interface.

Pathogens in FRI - Do bugs matter? - An analysis of FRI studies to assess your enemy

Fracture-related infection (FRI) is a devasting complication for both patients and their treating Orthopaedic surgeon that can lead to loss of limb function or even amputation. The unique and unpredictable features of FRI make its diagnosis and treatment a significant challenge. It has substantial morbidity and financial implications for patients, their families and healthcare providers. In this article, we perform an in-depth and comprehensive review of FRI through recent and seminal literature to highlight evolving definitions, diagnostic and treatment approaches, focusing on common pathogens such as Staphylococcus aureus, polymicrobial infections and multi-drug-resistant organisms (MDRO). Furthermore, multiple resistance mechanisms and adaptations for microbial survival are discussed, as well as modern evidence-based medical and surgical advancements in treatment strategies in combating FRI.

Polycaprolactone-MXene coating for controlling initial biodegradation of magnesium implant via near-infrared light

The mechanical strength of magnesium implants undergoes a rapid decline after implantation due to bioabsorption, which can lead to the risk of rupture. To ensure sustained mechanical strength and initiate bioabsorption selectively upon specific external stimuli until the bone regains sufficient support, we developed a biosafe near-infrared light (NIR)-sensitive polymer coating using polycaprolactone (PCL) and Ti3C2 (MXenes). The synthetic MXene powders were characterized using SEM, EDS, and XRD, and the amount of MXenes had a proliferation-promoting effect on MC3T3-E1, as observed through cell assays. The PCL-MXene coating was successfully prepared on the magnesium surface using the casting coating method, and it can protect the magnesium surface for up to 28 days by decreasing the corrosion ratio. However, the coating can be easily degraded after exposure to NIR light for 20 minutes to expose the magnesium substrate, especially in a liquid environment. Meanwhile, the magnesium implant with the PCL-MXene coating has no cytotoxicity toward MC3T3-E1. These findings can provide a new solution for the development of controlled degradation implants.

The global burden of fracture-related infection: can we do better?

Fracture-related infection is a major complication related to musculoskeletal injuries that not only has important clinical consequences, but also a substantial socioeconomic impact. Although fracture-related infection is one of the oldest disease entities known to mankind, it has only recently been defined and, therefore, its global burden is still largely unknown. In this Personal View, we describe the origin of the term fracture-related infection, present the available data on its global impact, and discuss important aspects regarding its prevention and management that could lead to improved outcomes in both high-resource and low-resource settings. We also highlight the need for health-care systems to be adequately compensated for the high cost of human resources (trained staff) and well-equipped facilities required to adequately care for these complex patients. Our aim is to increase awareness among clinicians and policy makers that fracture-related infection is a disease entity that deserves prioritisation in terms of research, with the goal to standardise treatment and improve patient outcomes on a global scale.

Factors affecting risk of recurrence with periprosthetic infection in shoulder arthroplasty

BACKGROUND

The goal of treating periprosthetic infection, besides its eradication, is to avoid recurrence. The purpose of this study was to evaluate the impact of increasing Infection Severity (IS) score (based on the 2018 International Consensus Meeting on Orthopedic Infections statement), single-stage revision, and pathogenicity of the infective organism on the risk of infection recurrence.

METHODS

A database of 790 revisions performed by a single surgeon from 2004-2020 was reviewed for patients with minimum 2-year follow-up and ≥1 positive culture finding and/or pathology result from the revision surgical procedure. In total, 157 cases performed in 144 patients met the inclusion criteria. These cases were then categorized by infection probability (IS score) according to the 2018 consensus statement. Of 157 cases, 46 (29%) were classified as definitely or probably infected; 25 (16%), possibly infected; and 86 (55%), unlikely to be infected. Additionally, patients were grouped by single-stage surgery and pathogenicity of the infective organism.

RESULTS

A recurrence in this study was classified as the growth of the same organism in any patient requiring revision surgery. The 86 cases in the group with unlikely infection showed a recurrence rate of 2.3%. The 25 cases in the group with possible infection showed a recurrence rate of 12%. The 46 cases in the group with definite or probable infection showed a recurrence rate of 17.4%. Patients in the definite/probable infection group had a higher rate of recurrence than those in the groups with possible infection and unlikely infection (P = .009). The IS score was higher in the recurrence group than the non-recurrence group (7.5 ± 4.3 vs. 3.9 ± 3.4, P < .001). Overall, patients who underwent 1-stage revision had a 5.0% recurrence rate, but among the 34 patients with an infection classification of definite or probable who underwent 1-stage revision, the recurrence rate was 5.9%. Cases of highly virulent methicillin-resistant Staphylococcus aureus also showed a recurrence rate of 30.8% compared with 4.0% and 5.9% for Cutibacterium acnes and coagulase-negative staphylococci, respectively (P = .005).

CONCLUSION

Recurrent infection after treatment of a periprosthetic infection is associated with increasing severity scores, as defined in the 2018 consensus statement, and more aggressive microorganisms. However, a single-stage surgical procedure, even in patients with higher IS scores, did not impart a significantly increased risk of recurrence.

Proteomic analysis of exosomal proteins associated with bone healing speed in a rat tibial fracture model

This study investigates the impact of exosomes on bone fracture healing in a rat tibial model, distinguishing between fast and slow healing processes. Bone healing and protein expression were assessed through X-ray examinations, hematoxylin and eosin staining, and immunohistochemical staining. Exosomes were isolated, characterized and subjected to liquid chromatography-mass spectrometry for protein analysis. Molecular differences were explored using differentially expressed protein analysis, Kyoto Encyclopedia of Genes and Genomes pathway enrichment and protein-protein interaction networks. Differential bone healing patterns and protein expressions were observed between the control and model groups. Exosomes were successfully isolated and characterized, revealing 2004 identified proteins, including distinct expression profiles. Notably, ribosomal proteins, ferritin and beta-actin emerged as pivotal players in bone fracture healing. This study unveils dynamic changes in bone healing and underscores the role of exosomes in the process. Identified proteins and pathways offer valuable insights for developing innovative therapeutic strategies for bone healing.

Delayed flail chest from osteomyelitis and malnutrition that emerged 3 weeks after blunt chest trauma: a case report

We present the case of a victim of a motor vehicle accident in his late 60s who suffered from severe torso injuries. He initially presented with abdominal and chest pain, and underwent emergency laparotomy for hemoperitoneum. After surgery, the patient developed pneumonia and septicemia, which were responsive to antibiotics. The patient was treated with mechanical ventilation in the intensive care unit for approximately 10 days and experienced a severe weight loss of approximately 30%, but slowly recovered without dyspnea. Notably, on hospital day 24, he experienced sudden respiratory distress and flail motion of the chest wall in a general ward. This late presentation of flail chest was attributed to non-union at rib fracture sites, and was likely exacerbated by malnutrition and osteomyelitis. Surgical stabilization of rib fractures and excision of the infected rib were successfully performed. The findings from this case highlight the complexity of managing delayed onset of flail chest. The findings from this case suggest the importance of vigilance for late emerging complications in patients with trauma, even when initial symptoms are absent.

The surgical management of fracture-related infection. Surgical strategy selection and the need for early surgical intervention

The aim of this narrative review is to describe the various surgical management strategies employed in fracture-related infection (FRI), to explore how they are selected and discuss the rationale for early surgical intervention. Surgical treatment options in patients with FRI include debridement, antibiotics and implant retention (DAIR), revision (exchange) or removal. In selecting a treatment strategy, a variety of factors need to be considered, including the condition of the bone, soft tissues, host and causative microorganism. Irrespective of the selected treatment strategy, prompt surgical intervention should be considered in order to confirm the diagnosis of an FRI, to identify the causative organism, remove necrotic or non-viable tissue that can serve as a nidus for ongoing infection, ensure a healthy soft tissue envelope and to prevent the vicious cycle of infection associated with skeletal and/or implant instability. Ultimately, the objective is to prevent the establishment of a persistent infection. Urgent surgery may be indicated in case of active, progressive disease with systemic deterioration, local progression of infection, deterioration of soft tissues, or progressive fracture instability. In case of static disease, the patient should be monitored closely and surgery can be performed on an elective basis, allowing adequate time for optimisation of the host through risk factor modification, optimisation of the soft tissues and careful planning of the surgery.

The critical impact of traumatic muscle loss on fracture healing: Basic science and clinical aspects

Musculoskeletal trauma, specifically fractures, is a leading cause of patient morbidity and disability worldwide. In approximately 20% of cases with fracture and related traumatic muscle loss, bone healing is impaired leading to fracture nonunion. Over the past few years, several studies have demonstrated that bone and the surrounding muscle tissue interact not only anatomically and mechanically but also through biochemical pathways and mediators. Severe damage to the surrounding musculature at the fracture site causes an insufficiency in muscle-derived osteoprogenitor cells that are crucial for fracture healing. As an endocrine tissue, skeletal muscle produces many myokines that act on different bone cells, such as osteoblasts, osteoclasts, osteocytes, and mesenchymal stem cells. Investigating how muscle influences fracture healing at cellular, molecular, and hormonal levels provides translational therapeutic solutions to this clinical challenge. This review provides an overview about the contributions of surrounding muscle tissue in directing fracture healing. The focus of the review is on describing the interactions between bone and muscle in both healthy and fractured environments. We discuss current progress in identifying the bone-muscle molecular pathways and strategies to harness these pathways as cues for accelerating fracture healing. In addition, we review the existing challenges and research opportunities in the field.

Fracture-Related Infection-Epidemiology, Etiology, Diagnosis, Prevention, and Treatment

BACKGROUND

Fracture-related infection (FRI) is a challenge to physicians and other workers in health care. In 2018, there were 7253 listed cases of FRI in Germany, corresponding to an incidence of 10.7 cases per 100 000 persons per year.

METHODS

This review is based on pertinent publications retrieved from a search in PubMed with the search terms "fracture," "infection," "guideline," and "consensus." Aside from the primary literature, international guidelines and consensus recommendations were evaluated as well.

RESULTS

FRI arise mainly from bacterial contamination of the fracture site. Staphylococcus aureus is the most commonly detected pathogen. The treatment is based on surgery and antibiotics and should be agreed upon by an interdisciplinary team; it is often difficult because of biofilm formation. Treatment options include implant-preserving procedures and single-stage, two-stage, or multi-stage implant replacement. Treatment failure occurs in 10.3% to 21.4% of cases. The available evidence on the efficacy of various treatment approaches is derived mainly from retrospective cohort studies (level III evidence). Therefore, periprosthetic joint infections and FRI are often discussed together.

CONCLUSION

FRI presents an increasing challenge. Preventive measures should be optimized, and the treatment should always be decided upon by an interdisciplinary team. Only low-level evidence is available to date to guide diagnostic and treatment decisions. High-quality studies are therefore needed to help us meet this challenge more effectively.

A bending model for assessing relative stiffness and strength of orthopaedic fixation constructs

BACKGROUND

The purpose of this study is to develop a simple and reproducible bending model that is compatible with a wide range of orthopaedic fixation devices and 3D printed spacers.

METHODS

A robust 4-point bending model was constructed by securing sawbones blocks with different orthopaedic fixation device constructs. Stress strain curves derived from a fundamental mechanics model were used to assess the effect of bone density, type of hardware (staple vs intramedullary beam), the use of dynamic compression, orientation of staples (dorsal vs plantar), and the use of 3D printed titanium spacers.

FINDINGS

The high throughput 4-point bending model is simple enough that the methods can be easily repeated to assess a wide range of fixation methods, while complex enough to provide clinically relevant information.

INTERPRETATIONS

It is recommended that this model is used to assess a large initial set of fixation methods in direct and straightforward comparisons.

Interfragmentary strain measurement post-fixation to guide intraoperative decision making: a narrative review

PURPOSE

Interfragmentary strain influences whether a fracture will undergo direct and indirect fracture healing. Orthopedic trauma surgeons modulate strain and create optimal biomechanical environments for specific fracture patterns using fixation constructs. However, objective intraoperative interfragmentary strain measurement does not currently inform fixation strategy in common practice. This review identifies potential methods and technologies to enable intraoperative strain measurement for guiding optimal fracture fixation strategies.

METHODS

PubMed, Scopus, and Web of Science were methodologically queried for manuscripts containing terms related to "bone fracture," "strain," "measurement," and "intraoperative." Manuscripts were systematically screened for relevance and adjudicated by three reviewers. Relevant articles describing methods to measure interfragmentary strain intraoperatively were summarized.

RESULTS

After removing duplicates, 1404 records were screened initially. There were 49 manuscripts meeting criteria for in-depth review. Of these, four reports were included in this study that described methods applicable to measuring interfragmentary strain intraoperatively. Two of these reports described a method using instrumented staples, one described optical tracking of Kirschner wires, and one described using a digital linear variable displacement transducer with a custom external fixator.

CONCLUSION

The four reports identified by this review describe potential methods to quantify interfragmentary strain after fixation. However, further studies are needed to confirm the precision and accuracy of these measurements across a range of fractures and fixation methods. Additionally, described methods require the insertion and likely removal of additional implants into the bone. Ideally, innovations that measure interfragmentary strain intraoperatively would provide dynamic biomechanical feedback for the surgeon to proactively modulate construct stability.

Traumatic cubitus valgus consequent of distal humeral fracture: Two case studies from the Holocene Later Stone Age in southern Africa

OBJECTIVES

Distal fractures of the humerus and their complications have rarely been described or analysed in the palaeopathological literature. The objective of this study was to evaluate two cases of distal humeral fracture with associated cubitus valgus observed in two individuals from the context of the Later Stone Age (LSA) in southern Africa.

MATERIALS

Skeletal remains of two individuals. A middle-aged female radiocarbon dated to c.160 BP and a middle-aged male radiocarbon dated to c.2 300 BP.

METHODS

Remains were macroscopically and radiographically assessed for injury.

RESULTS

Both cases presented with healed antemortem injury to the right elbow attributed to possible falls. Distal humeral fracture resulted in non-union of the lateral epicondyle with extensive morphological changes to the elbow joint including an increased carrying angle. Morphological and osteoarthritic changes suggest a survival period of several years post-injury.

SIGNIFICANCE

Cubitus valgus following traumatic injury has rarely been reported amongst historic or prehistoric populations. The described injuries would have had physical and functional consequences, raising questions relating to probable care received during the healing process. The elbow injuries would have resulted in restricted motion and instability of the elbow joint, with a high likelihood of ulnar neuropathy.

LIMITATIONS

The contextual information for these individuals is limited and do not permit broader population level study.

SUGGESTIONS FOR FURTHER RESEARCH

Formal biomechanical analysis including cross-sectional geometry analysis will provide further information regarding complications and strengthen the diagnosis of ulnar neuropathy. Further research is necessary on the prevalence and complications of humeral fracture.

Increased Osteoblast GαS Promotes Ossification by Suppressing Cartilage and Enhancing Callus Mineralization During Fracture Repair in Mice

GαS, the stimulatory G protein α-subunit that raises intracellular cAMP levels by activating adenylyl cyclase, plays a vital role in bone development, maintenance, and remodeling. Previously, using transgenic mice overexpressing GαS in osteoblasts (GS-Tg), we demonstrated the influence of osteoblast GαS level on osteogenesis, bone turnover, and skeletal responses to hyperparathyroidism. To further investigate whether alterations in GαS levels affect endochondral bone repair, a postnatal bone regenerative process that recapitulates embryonic bone development, we performed stabilized tibial osteotomy in male GS-Tg mice at 8 weeks of age and examined the progression of fracture healing by micro-CT, histomorphometry, and gene expression analysis over a 4-week period. Bone fractures from GS-Tg mice exhibited diminished cartilage formation at the time of peak soft callus formation at 1 week post-fracture followed by significantly enhanced callus mineralization and new bone formation at 2 weeks post-fracture. The opposing effects on chondrogenesis and osteogenesis were validated by downregulation of chondrogenic markers and upregulation of osteogenic markers. Histomorphometric analysis at times of increased bone formation (2 and 3 weeks post-fracture) revealed excess fibroblast-like cells on newly formed woven bone surfaces and elevated osteocyte density in GS-Tg fractures. Coincident with enhanced callus mineralization and bone formation, GS-Tg mice showed elevated active β-catenin and Wntless proteins in osteoblasts at 2 weeks post-fracture, further substantiated by increased mRNA encoding various canonical Wnts and Wnt target genes, suggesting elevated osteoblastic Wnt secretion and Wnt/β-catenin signaling. The GS-Tg bony callus at 4 weeks post-fracture exhibited greater mineral density and decreased polar moment of inertia, resulting in improved material stiffness. These findings highlight that elevated GαS levels increase Wnt signaling, conferring an increased osteogenic differentiation potential at the expense of chondrogenic differentiation, resulting in improved mechanical integrity. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC. on behalf of American Society for Bone and Mineral Research.

An analytical model of lateral condylar plate working length

BACKGROUND

The locking plate is a common device to treat distal femur fractures. Healing is affected by construct stiffness, thus many surgeon-controlled variables such as working length have been examined for their effects on strain at the fracture. No convenient analytical model which aids surgeons in determining working length has yet been described. We propose an analytical model and compare it to finite element analysis and cadaveric biomechanical testing.

METHODS

First, an analytical model based on a cantilever beam equation was derived. Next, a finite element model was developed based on a CT scan of a "fresh-frozen" cadaveric femur. Third, biomechanical testing in single-leg stance loading was performed on the cadaver. In all methods, strain at the fracture was recorded. An ANCOVA test was conducted to compare the strains.

FINDINGS

In all models, as the working length increased so did strain. For strain at the fracture, the shortest working length (35 mm) had a strain of 8% in the analytical model, 9% in the finite element model, and 7% for the cadaver. The longest working length (140 mm) demonstrated strain of 15% in the analytical model, and the finite element and biomechanical tests both demonstrated strain of 14%.

INTERPRETATION

The strain predicted by the analytical model was consistent with the strain observed in both the finite element and biomechanical models. As demonstrated in existing literature, increasing the working length increases strain at the fracture site. Additional work is required to refine and establish validity and reliability of the analytical model.

A longitudinal rat model for assessing postoperative recovery and bone healing following tibial osteotomy and plate fixation

BACKGROUND

Rodent models are commonly employed to validate preclinical disease models through the evaluation of postoperative behavior and allodynia. Our study investigates the dynamic interplay between pain and functional recovery in the context of traumatic osteotomy and surgical repair. Specifically, we established a rat model of tibial osteotomy, followed by internal fixation using a 5-hole Y-plate with 4 screws, to explore the hypothesis that histological bone healing is closely associated with functional recovery.

OBJECTIVE

Our primary objective was to assess the correlation between bone healing and functional outcomes in a rat model of tibial osteotomy and plate fixation.

METHODS

Seventeen male Sprague-Dawley rats underwent a metaphyseal transverse osteotomy of the proximal tibia, simulating a fracture-like injury. The resultant bone defect was meticulously repaired by realigning and stabilizing the bone surfaces with the Y-plate. To comprehensively assess recovery and healing, we performed quantitative and qualitative evaluations at 2, 4, 6, and 8 weeks post-surgery. Evaluation methods included micro-CT imaging, X-ray analysis, and histological examination to monitor bone defect healing. Concurrently, we employed video recording and gait analysis to evaluate functional recovery, encompassing parameters such as temporal symmetry, hindlimb duty factor imbalance, phase dispersion, and toe spread.

RESULTS

Our findings revealed complete healing of the bone defect at 8 weeks, as confirmed by micro-CT and histological assessments. Specifically, micro-CT data showed a decline in fracture volume over time, indicating progressive healing. Histological examination demonstrated the formation of new trabecular bone and the resolution of inflammation. Importantly, specific gait analysis parameters exhibited longitudinal changes consistent with bone healing. Hindlimb duty factor imbalance, hindlimb temporal symmetry, and phase dispersion correlated strongly with the healing process, emphasizing the direct link between bone healing and functional outcomes.

CONCLUSIONS

The establishment of this tibia osteotomy model underscores the association between bone healing and functional outcomes, emphasizing the feasibility of monitoring postoperative recovery using endpoint measurements. Our overarching objective is to employ this model for assessing the local efficacy of drug delivery devices in ameliorating post-surgical pain and enhancing functional recovery.

Staphylococcus aureus From an Acute Fracture-related Infection Displays Important Bacteriological and Histopathologic Differences From a Chronic Equivalent in a Murine Bone Infection Model

BACKGROUND

Staphylococcus aureus is the leading pathogen in fracture-related infection. Previous in vitro experiments, in vivo testing in wax moth larvae, and genomic analysis of clinical S. aureu s isolates from fracture-related infection identified low-virulence (Lo-SA5464) and high-virulence (Hi-SA5458) strains. These findings correlated with acute fracture-related infection induced by Hi-SA5458, whereas Lo-SA5464 caused a chronic fracture-related infection in its human host. However, it remains unclear whether and to what extent the causative pathogen is attributable to these disparities in fracture-related infections.

QUESTION/PURPOSE

Are there differences in the course of infection when comparing these two different clinical isolates in a murine fracture-related infection model, as measured by (1) clinical observations of weight loss, (2) quantitative bacteriology, (3) immune response, and (4) radiographic and histopathologic morphology?

METHODS

Twenty-five (including one replacement animal) female (no sex-specific influences expected), skeletally mature C57Bl/6N inbred mice between 20 and 28 weeks old underwent femoral osteotomy stabilized by titanium locking plates. Fracture-related infection was established by inoculation of high-virulence S. aureus EDCC 5458 (Hi-SA5458) or low-virulence S. aureus EDCC 5464 (Lo-SA5464) in the fracture gap. Each of these groups consisted of 12 randomly assigned animals. Mice were euthanized 4 and 14 days postsurgery, resulting in six animals per group and timepoint. The severity and progression of infection were assessed in terms of clinical observation of weight loss, quantitative bacteriology, quantitative serum cytokine levels, qualitative analysis of postmortem radiographs, and semiquantitative histopathologic evaluation.

RESULTS

For clinical observations of weight change, no differences were seen at Day 4 between Hi-SA5458- and Lo-SA5464-infected animals (mean -0.6 ± 0.1 grams versus -0.8 ± 0.2 grams, mean difference -0.2 grams [95% CI -0.8 to 0.5 grams]; p =0.43), while at 14 days, the Hi-SA5458 group lost more weight than the Lo-SA5464 group (mean -1.55 ± 0.2 grams versus -0.8 ± 0.3 grams; mean difference 0.7 grams [95% CI 0.2 to 1.3 grams]; p = 0.02). Quantitative bacteriological results 4 days postoperatively revealed a higher bacterial load in soft tissue samples in Hi-SA5458-infected animals than in the Lo-SA5464-infected cohort (median 6.8 x 10 7 colony-forming units [CFU]/g, range 2.2 x 10 7 to 2.1 x 10 9 CFU/g versus median 6.0 x 10 6 CFU/g, range 1.8 x 10 5 to 1.3 x 10 8 CFU/g; difference of medians 6.2 x 10 7 CFU/g; p = 0.03). At both timepoints, mice infected with the Hi-SA5458 strain also displayed higher proportions of bacterial dissemination into organs than Lo-SA5464-infected animals (67% [24 of 36 organs] versus 14% [five of 36 organs]; OR 12.0 [95% CI 3.7 to 36]; p < 0.001). This was accompanied by a pronounced proinflammatory response on Day 14, indicated by increased serum cytokine levels of interleukin-1β (mean 9.0 ± 2.2 pg/mL versus 5.3 ± 1.5 pg/mL; mean difference 3.6 pg/mL [95% CI 2.0 to 5.2 pg/mL]; p < 0.001), IL-6 (mean 458.6 ± 370.7 pg/mL versus 201.0 ±89.6 pg/mL; mean difference 257.6 pg/mL [95% CI 68.7 to 446.5 pg/mL]; p = 0.006), IL-10 (mean 15.9 ± 3.5 pg/mL versus 9.9 ± 1.0 pg/mL; mean difference 6.0 pg/mL [95% CI 3.2 to 8.7 pg/mL]; p < 0.001), and interferon-γ (mean 2.7 ± 1.9 pg/mL versus 0.8 ± 0.3 pg/mL; mean difference 1.8 pg/mL [95% CI 0.5 to 3.1 pg/mL]; p = 0.002) in Hi-SA5458-infected compared with Lo-SA5464-infected animals. The semiquantitative histopathologic assessment on Day 4 revealed higher grades of granulocyte infiltration in Hi-SA5458-infected animals (mean grade 2.5 ± 1.0) than in Lo-SA5464-infected animals (mean grade 1.8 ± 1.4; mean difference 0.7 [95% CI 0.001 to 1.4]; p = 0.0498). On Day 14, bone healing at the fracture site was present to a higher extent in Lo-SA5464-infected animals than in Hi-SA5458-infected animals (mean grade 0.2 ± 0.4 versus 1.8 ± 1.2; mean difference -1.6 [95% CI -2.8 to -0.5]; p = 0.008).

CONCLUSION

Similar to septic infection in a human host, infection with Hi-SA5458 in this murine model was characterized by a higher bacterial load, more-pronounced systemic dissemination, and stronger systemic and local inflammation. Thus, there is strong support for the idea that pathogenic virulence plays a crucial role in fracture-related infections. To confirm our observations, future studies should focus on characterizing S. aureus virulence at the genomic and transcriptomic levels in more clinical isolates and patients. Comparing knockout and wildtype strains in vitro and in vivo, including the S. aureus strains studied, could confirm our findings and identify the genomic features responsible for S. aureus virulence in fracture-related infections.

CLINICAL RELEVANCE

For translational use, virulence profiles of S. aureus may be useful in guiding treatment decisions in the future. Once specific virulence targets are identified, one approach to fracture-related infections with high-virulence strains might be the development of antivirulence agents, particularly to treat or prevent septic dissemination. For fracture-related infections with low virulence, prolonged antimicrobial therapy or exchange of an indwelling implant might be beneficial owing to slower growth and persistence capacity.

Anatomical characteristics of the alveolar process and basal bone that have an effect on socket healing

Following tooth extraction, a sequence of events takes place in order to close the wound and restore tissue homeostasis, a process called socket healing. The outcome of socket healing includes a marked reduction of the ridge dimensions. The amount of tissue loss that occurs during healing is influenced by several local and systemic factors. Thus, the aim of the present review was to describe the effect of anatomical characteristics of the alveolar process and basal bone on the socket healing outcome. The studies included showed that the quantity (number) and quality (composition) of socket walls exhibited a significant influence on the ridge diminution. A damaged socket (3 walls or less), as well as a thin buccal bone wall, which quickly resorbs negatively affected the healing outcome. Periodontally compromised sockets appeared to promote more extensive dimensional changes. Angulation between tooth and basal bone in addition to basal bone dimensions may also have altered the wound environment and influenced socket healing. The findings from the present review suggest that some anatomical characteristics of the alveolar process and basal bone have an effect on socket healing.

Treatment of Fracture-Related Infection after Pelvic Fracture

BACKGROUND

The management of pelvic fractures is a significant challenge. Surgical site infection can result in the need for revision surgery, cause functional impairment, and lead to a prolonged length of stay and increased treatment costs. Although reports on fracture-related infection (FRI) after pelvic fracture fixation are sparsely reported in the literature, it is a serious complication. This study analysed patients with FRIs after pelvic fracture regarding patient characteristics, treatment strategies, and an evaluation of risk factors for FRI.

METHODS

In this retrospective single-centre study, FRI was diagnosed based on clinical symptoms of infection and a positive culture of a bacterial infection. Depending on the severity and acuteness of the infection, osseous stabilization was restored either via implant retention (stable implant, no osteolysis), exchange (loose implant or bony defect), or external fixation (recurrence of infection after prior implant retaining revision). Healing of infection was defined as no sign of recurring infection upon clinical, radiological, and laboratory examination in the last follow-up visit.

RESULTS

The FRI rate in our patient population was 7.5% (24/316). In 8/24 patients, the FRI occurred within the first three weeks after initial surgery (early) and 16/24 presented with a late onset of symptoms of FRI. A strategy of debridement, antibiotics, and implant retention (DAIR) was successful in 9/24 patients with FRI after pelvic fracture. A total of 10 patients required an exchange of osteo-synthetic implants, whereof three were exchanged to an external fixator. In five patients, we removed the implant because the fracture had already consolidated at the time of revision for infection. A total of 17/24 patients had a poly-microbial infection after a pelvic fracture and 3/24 patients died from post-traumatic multi-organ failure within the first 6 months after trauma. There were no cases of persistent infection within the remaining 21 patients.

CONCLUSIONS

Although poly-microbial infection is common in FRI after pelvic fracture, the recurrence rate of infection is relatively low. A complex pelvic trauma with significant soft tissue injury is a risk factor for recurrent infection and multiple revisions. A strategy of DAIR can be successful in patients with a stable implant. In cases with recurrent infection or an unstable fracture site, the exchange of implants should be considered.

Microbiological Profile of Fracture Related Infection at a UK Major Trauma Centre

Fracture Related Infection (FRI) represents one of the biggest challenges for Trauma and Orthopaedic surgery. A better understanding of the microbiological profile should assist with decision-making and optimising outcomes. Our primary aim was to report on the microbiological profile of FRI cases treated over a six-year period at one of Europe's busiest trauma centres. Secondarily, we sought to correlate our findings with existing anti-microbiological protocols and report on diagnostic techniques employed in our practice. All adult cases of FRI treated in our institution between 2016 and 2021 were identified, retrospectively. We recorded patient demographics, diagnostic strategies, causative organisms and antibiotic susceptibilities. There were 330 infection episodes in 294 patients. A total of 463 potentially pathogenic organisms (78 different species) were identified from cultures, of which 57.2% were gram-positive and 39.7% gram-negative. Polymicrobial cultures were found in 33.6% of cases and no causative organism was found in 17.5%. The most prevalent organisms were Staphylococcus aureus (24.4%), coagulase-negative Staphylococci (14%), Pseudomonas aeruginosa (8.2%), Enterobacter species (7.8%) and Escherichia coli (6.9%). Resistant gram-positive organisms (methicillin resistant Staphylococcus aureus or vancomycin-resistant Enterococci) were implicated in 3.3% of infection episodes and resistant gram-negatives (extended-spectrum beta-lactamase, ampC or carbapenemase-producing bacteria) in 13.6%. The organisms cultured in 96.3% of infection episodes would have been covered by our empirical systemic antibiotic choice of teicoplanin and meropenem. To our knowledge, this is the largest reported single-centre cohort of FRIs from a major trauma centre. Our results demonstrate patterns in microbiological profiles that should serve to inform the decision-making process regarding antibiotic choices for both prophylaxis and treatment.

Enhancing Polymethyl Methacrylate Prostheses for Cranioplasty with Ti mesh Inlays

Biocompatible polymers such as polymethyl methacrylate (PMMA), despite fulfilling biomedical aspects, lack the mechanical strength needed for hard-tissue implant applications. This gap can be closed by using composites with metallic reinforcements, as their adaptable mechanical properties can overcome this problem. Keeping this in mind, novel Ti-mesh-reinforced PMMA composites were developed. The influence of the orientation and volume fraction of the mesh on the mechanical properties of the composites was investigated. The composites were prepared by adding Ti meshes between PMMA layers, cured by hot-pressing above the glass transition temperature of PMMA, where the interdiffusion of PMMA through the spaces in the Ti mesh provided sufficient mechanical clamping and adhesion between the layers. The increase in the volume fraction of Ti led to a tremendous improvement in the mechanical properties of the composites. A significant anisotropic behaviour was analysed depending on the direction of the mesh. Furthermore, the shaping possibilities of these composites were investigated via four-point bending tests. High shaping possibility was found for these composites when they were shaped at elevated temperature. These promising results show the potential of these materials to be used for patient-specific implant applications.

Osteomyelitis with abscess associated with acute closed upper humerus fracture in an adult: A case report

A 64-year-old female presented with malaise and fever 11 days after a closed, minimally displaced humerus surgical neck fracture. MR imaging revealed an abscess around the fracture, which is a very rare occurrence in adults. Two open debridements and IV antibiotics eradicated the infection. Reverse total shoulder arthroplasty was eventually performed for fracture nonunion.

Treatment and outcome of fracture-related infection of the clavicle

INTRODUCTION

The number of operatively treated clavicle fractures has increased over the past decades. Consequently, this has led to an increase in secondary procedures required to treat complications such as fracture-related infection (FRI). The primary objective of this study was to assess the clinical and functional outcome of patients treated for FRI of the clavicle. The secondary objectives were to evaluate the healthcare costs and propose a standardized protocol for the surgical management of this complication.

METHODS

All patients with a clavicle fracture who underwent open reduction and internal fixation (ORIF) between 1 January 2015 and 1 March 2022 were retrospectively evaluated. This study included patients with an FRI who were diagnosed and treated according to the recommendations of a multidisciplinary team at the University Hospitals Leuven, Belgium.

RESULTS

We evaluated 626 patients with 630 clavicle fractures who underwent ORIF. In total, 28 patients were diagnosed with an FRI. Of these, eight (29%) underwent definitive implant removal, five (18%) underwent debridement, antimicrobial treatment and implant retention, and fourteen patients (50%) had their implant exchanged in either a single-stage procedure, a two-stage procedure or after multiple revisions. One patient (3.6%) underwent resection of the clavicle. Twelve patients (43%) underwent autologous bone grafting (tricortical iliac crest bone graft (n = 6), free vascularized fibular graft (n = 5), cancellous bone graft (n = 1)) to reconstruct the bone defect. The median follow-up was 32.3 (P₂₅-P₇₅: 23.9-51.1) months. Two patients (7.1%) experienced a recurrence of infection. The functional outcome was satisfactory, with 26 out of 28 patients (93%) having full range of motion. The median healthcare cost was € 11.506 (P₂₅-P₇₅: € 7.953-23.798) per patient.

CONCLUSION

FRI is a serious complication that can occur after the surgical treatment of clavicle fractures. In our opinion, when treated adequately using a multidisciplinary patient-specific approach, the outcome of patients with an FRI of the clavicle is good. The median healthcare costs of these patients are up to 3.5 times higher compared to non-infected operatively treated clavicle fractures. Although not studied individually, we consider factors such as the size of the bone defect, condition of the soft tissue, and patient demand important when it comes to guiding our surgical decision making in cases of osseous defects.

Calcium Phosphate Cements as Carriers of Functional Substances for the Treatment of Bone Tissue

Interest in calcium phosphate cements as materials for the restoration and treatment of bone tissue defects is still high. Despite commercialization and use in the clinic, the calcium phosphate cements have great potential for development. Existing approaches to the production of calcium phosphate cements as drugs are analyzed. A description of the pathogenesis of the main diseases of bone tissue (trauma, osteomyelitis, osteoporosis and tumor) and effective common treatment strategies are presented in the review. An analysis of the modern understanding of the complex action of the cement matrix and the additives and drugs distributed in it in relation to the successful treatment of bone defects is given. The mechanisms of biological action of functional substances determine the effectiveness of use in certain clinical cases. An important direction of using calcium phosphate cements as a carrier of functional substances is the volumetric incorporation of anti-inflammatory, antitumor, antiresorptive and osteogenic functional substances. The main functionalization requirement for carrier materials is prolonged elution. Various release factors related to the matrix, functional substances and elution conditions are considered in the work. It is shown that cements are a complex system. Changing one of the many initial parameters in a wide range changes the final characteristics of the matrix and, accordingly, the kinetics. The main approaches to the effective functionalization of calcium phosphate cements are considered in the review.

Great debates in trauma biomechanics

At the 2021 annual meeting of the Orthopaedic Trauma Association, the Basic Science Focus Forum hosted its first ever debate-style symposium focused on biomechanics and fracture repair. The 3 subjects of debate were "Mechanics versus Biology-Which is 'More Important' to Consider?" "Locked Plate versus Forward Dynamization versus Reverse Dynamization-Which Way Should I Go?" and "Sawbones versus Cadaver Models-What Should I Believe Most?" These debates were held because fracture healing is a highly organized synergistic response between biological factors and the local mechanical environment. Multiple studies have demonstrated that both factors play roles in governing bone healing responses, and the causal relationships between the 2 remain unclear. The lack of clarity in this space has led to a spectrum of research with the common goal of helping surgeons make good decisions. Before reading further, the reader should understand that the questions posed in the debate titles are unanswerable and might represent a false choice. Instead, the reader should appreciate that the debates were held to gain a more thorough understanding of these topics based on the current state of the art of experimental and clinical studies, by using an engaging and thought-provoking format.

How controlled motion alters the biophysical properties of musculoskeletal tissue architecture

INTRODUCTION

Movement is fundamental to the normal behaviour of the hand, not only for day-to-day activity, but also for fundamental processes like development, tissue homeostasis and repair. Controlled motion is a concept that hand therapists apply to their patients daily for functional gains, yet the scientific understanding of how this works is poorly understood.

PURPOSE OF THE ARTICLE

To review the biology of the tissues in the hand that respond to movement and provide a basic science understanding of how it can be manipulated to facilitate better functionThe review outlines the concept of controlled motion and actions across the scales of tissue architecture, highlighting the the role of movement forces in tissue development, homeostasis and repair. The biophysical behaviour of mechanosensitve tissues of the hand such as skin, tendon, bone and cartilage are discussed.

CONCLUSION

Controlled motion during early healing is a form of controlled stress and can be harnessed to generate appropriate reparative tissues. Understanding the temporal and spatial biology of tissue repair allows therapists to tailor therapies that allow optimal recovery based around progressive biophysical stimuli by movement.

Analyzing risk factors for treatment failure in fracture-related infection

INTRODUCTION

Fracture-related infection (FRI) represents a challenging clinical scenario. Limited evidence exists regarding treatment failure after initial management of FRI. The objective of our investigation was to determine incidence and risk factors for treatment failure in FRI.

MATERIALS AND METHODS

We conducted a retrospective review of patients treated for FRI between 2011 and 2015 at three level 1 trauma centers. One hundred and thirty-four patients treated for FRI were identified. Demographic and clinical variables were extracted from the medical record. Treatment failure was defined as the need for repeat debridement or surgical revision seven or more days after the presumed final procedure for infection treatment. Univariate comparisons were conducted between patients who experienced treatment failure and those who did not. Multivariable logistic regression was conducted to identify independent associations with treatment failure.

RESULTS

Of the 134 FRI patients, 51 (38.1%) experienced treatment failure. Patients who failed were more likely to have had an open injury (31% versus 17%; p = 0.05), to have undergone implant removal (p = 0.03), and additional index I&D procedures (3.3 versus 1.6; p < 0.001). Most culture results identified a single organism (62%), while 15% were culture negative. Treatment failure was more common in culture-negative infections (p = 0.08). Methicillin-resistant Staphylococcus aureus (MRSA) was the most common organism associated with treatment failure (29%; p = 0.08). Multivariate regression demonstrated a statistically significant association between treatment failure and two or more irrigation and debridement (I&D) procedures (OR 13.22, 95% CI 4.77-36.62, p < 0.001) and culture-negative infection (OR 4.74, 95% CI 1.26-17.83, p = 0.02).

CONCLUSIONS

The rate of treatment failure following FRI continues to be high. Important risk factors associated with treatment failure include open fracture, implant removal, and multiple I&D procedures. While MRSA remains common, culture-negative infection represents a novel risk factor for failure, suggesting aggressive treatment of clinically diagnosed cases remains critical even without positive culture data.

LEVEL OF EVIDENCE

Retrospective cohort study; Level III.

Antibiotic-Loaded Coatings to Reduce Fracture-Related Infections: Retrospective Case Series of Patients with Increased Infectious Risk

Local antibiotic delivery strategies have been increasingly employed for the prevention of fracture-related infections (FRIs). The aim of this study is to evaluate the efficacy and safety of antibiotic-coated implants in the prevention of FRIs after surgical treatment in patients with increased infectious risk. A retrospective observational study has been conducted on patients with upper and lower limb fractures treated with internal fixation or prosthetic replacements, using a gentamicin coated nail (CN) and/or antibiotic-loaded hydrogel applied to the implant of choice (ALH). The study included 37 patients (20 M, 17 F), with a mean age of 63 years. The mean estimated preoperative infectious risk score was 6.4%. ALH was used in 27 cases, tibial CNs were implanted in 4 cases, and both were employed in 6 cases. The antibiotics used locally were gentamicin in 72.97% of cases (27 patients) and a combination of gentamicin + vancomycin in 27.03% of cases (10 patients). Mean follow-up was 32 months. Only one case (2.94%) showed onset of FRI at 5 months after surgery. Local antibiotic prophylaxis by coating resulted in a reduction in the incidence FRI, as compared to the estimated preoperative risk. The use of ALH allows for the choice of antibiotic; however, the application of antibiotics seems more nonuniform when applied to a nail.

Investigating effects of locally applied boric acid on fracture healing with and without low-level laser therapy

This study aimed to investigate the effects on fracture healing of locally applied boric acid (BA) with and without low-level laser therapy (LLLT). A unicortical femoral defect was surgically created on the anterolateral surface of proximal femur of each subject. The subjects, totaling 56 Wistar albino rats, were randomly allocated into four groups (n = 14 each): control, LLLT (λ = 905 μm, 10,000 Hz, 25 mW, and peak power 25 W), BA (40 mg/kg), and BA + LLLT groups. On the 30th day, the highest radiological score was recorded for the BA + LLLT group (3.63 [2-4]), followed by the BA (3.38 [2.75-3.75]), control (3 [2-3.25]), and LLLT (2.5 [1.25-3]) groups. On days 15 and 30 post-surgery, malondialdehyde levels were significantly lower among the BA + LLLT group compared to the control group (p < 0.001). On day 30, superoxide dismutase, catalase, and alkaline phosphatase levels were highest in the BA + LLLT group compared to the control group (p < 0.001). When the histopathological, immunofluorescence, and immunohistochemical findings on the 15th and 30th days were compared with the control group, a statistically significant difference was found for the BA and BA + LLLT groups (p ˂ 0.05). This study suggests that locally applied BA with LLLT may accelerate fracture healing.

First clinical results of 1-year follow-up of the femoral neck system for internal fixation of femoral neck fractures

BACKGROUND

Closed reduction and internal fixation (CRIF) is the preferred treatment to retain the native joint and maintain optimal functionality in femoral neck fractures. Sliding hip screw (SHS) and cannulated hip screws (CHS) are established CRIF options. SHS offer high biomechanical stability, whereas CHS are minimally invasive. These established systems have a 17-21% failure rate. The Femoral neck system (FNS) was recently developed to combine the advantages of both predecessors. The aim of this study was to describe the first clinical experience with this novel implant with special emphasis on the safety and efficacy.

METHODS

During a 1-year period all patients in our level-2 trauma centre with a FNF indicated for CRIF were treated using the FNS and evaluated at 2, 6, 12 weeks, 6 months and 1 year postoperatively using patient and fracture characteristics, surgical notes and radiographic imaging.

RESULTS

Thirty-four patients were included, mean age was 63 years (SD 8), 58.2% was female. Fractures were classified as Pauwels I (n = 10), Pauwels II (n = 15), Pauwels III (n = 9), Garden I (n = 1), Garden II (n = 17), Garden III (n = 12) and Garden IV (n = 4). Eight reoperations were reported after 1-year follow-up; osteosyntheses failed in 6 patients due to avascular necrosis (n = 4) and cut-out (n = 2). In two patients the implant was removed due to inexplicable pain. Age (< 65 years) was related to lower risk for failure. There was a trend for females having more failures.

CONCLUSION

This study indicates that the FNS is a potential safe and effective CRIF modality. Age (< 65 years) is an important factor to keep in mind when selecting patients for CRIF as it is related to lower risk for failure. Future long-term follow-up studies with larger populations should indicate if functional results and risk factors for failure are comparable to SHS or CHS.