Osteosynthesis aims to maintain fracture reduction until bone healing occurs, which is not achieved in case of mechanical fixation failure. One form of failure is plastic plate bending due to overloading, occurring in up to 17% of midshaft fracture cases and often necessitating reoperation. This study aimed to replicate in-vivo conditions in a cadaveric experiment and to validate a finite element (FE) simulation to predict plastic plate bending. Six cadaveric bones were used to replicate an established ovine tibial osteotomy model with locking plates in-vitro with two implant materials (titanium, steel) and three fracture gap sizes (30, 60, 80 mm). The constructs were tested monotonically until plastic plate deformation under axial compression. Specimen-specific FE models were created from CT images. Implant material properties were determined using uniaxial tensile testing of dog bone shaped samples. The experimental tests were replicated in the simulations. Stiffness, yield, and maximum loads were compared between the experiment and FE models. Implant material properties (Young's modulus and yield stress) for steel and titanium were 184 GPa and 875 MPa, and 105 GPa and 761 MPa, respectively. Yield and maximum loads of constructs ranged between 469–491 N and 652–683 N, and 759–995 N and 1252–1600 N for steel and titanium fixations, respectively. FE models accurately and quantitatively correctly predicted experimental results for stiffness (R2=0.96), yield (R2=0.97), and ultimate load (R2=0.97). FE simulations accurately predicted plastic plate bending in osteosynthesis constructs. Construct behavior was predominantly driven by the implant itself, highlighting the importance of modelling correct material properties of metal. The validated FE models could predict subject-specific load bearing capacity of osteosyntheses in vivo in preclinical or clinical studies. Acknowledgements: This study was supported by the AO Foundation via the AOTRAUMA Network (Grant No.: AR2021_03)

Patients with bone and muscle weakness from disuse have higher risk of fracture and worse post-injury mortality rates. The goal of this current study was to better inform post-fracture rehabilitation strategies by investigating if physical remobilization following disuse by hindlimb unloading improves osteochondral callus formation compared to continued disuse by hindlimb suspension (HLS). We hypothesized that continued HLS would impair callus bone and cartilage formation and that physical rehabilitation after HLS would increase callus properties. All animal procedures were approved by the VCU IACUC. Skeletally mature, male and female C57BL/6J mice (18 weeks) underwent HLS for 3 weeks. Mice then had their right femur fractured by open surgical dissection (stabilized with 24-gauge pin). Mice were then either randomly assigned to continued HLS or allow normal physical weight-bearing remobilization (HLS + R). Mice allowed normal cage activity throughout the experiment served as controls (GC). All mice were sacrificed 14-days following fracture with 4-8 mice (male and female) per treatment. Data analyzed by respective ANOVA with Tukey post-hoc (*p< 0.05; # p < 0.10). Male and female mice showed conserved and significant decreases in hindlimb callus bone formation from continued HLS versus HLS + R. Combining treatment groups regardless of mouse sex, histological analyses using staining on these same calluses demonstrated that HLS resulted in trends toward decreased cartilage cross-sectional area and increased osteoclast density in woven bone versus physically rehabilitated mice. In support of our hypothesis, physical remobilization increases callus bone formation following fracture compared to continued disuse potentially due to increased endochondral ossification and decreased bone resorption. In all, partial weight-bearing exercise immediately following fracture may improve callus healing compared to delayed rehabilitation regimens that are frequently used

Standard fixation for intra-articular distal humerus fracture is open reduction and internal fixation (ORIF). However, high energy fractures of the distal humerus are often accompanied with soft tissue injuries and or vascular injuries which limits the use of internal fixation. In our report, we describe a highly complex distal humerus fracture that showed promising healing via a ring external fixator. A 26-year-old man sustained a Gustillo Anderson Grade IIIB intra-articular distal humerus fracture of the non-dominant limb with bone loss at the lateral column. The injury was managed with aggressive wound debridement and cross elbow stabilization via a hinged ring external fixator. Post operative wound managed with foam dressing. Post-operatively, early controlled mobilization of elbow commenced. Fracture union achieved by 9 weeks and frame removed once fracture united. No surgical site infection or non-union observed throughout follow up. At 2 years follow up, flexion - extension of elbow is 20°- 100°, forearm supination 65°, forearm pronation 60° with no significant valgus or varus deformity. The extent of normal anatomic restoration in elbow fracture fixation determines the quality of elbow function with most common complication being elbow stiffness. Ring fixator is a non-invasive external device which provides firm stabilization of fracture while allowing for adequate soft tissue management. It provides continuous axial micro-movements in the frame which promotes callus formation while avoiding translation or angulation between the fragments. In appropriate frame design, they allow for early rehabilitation of joint where normal range of motion can be allowed in controlled manner immediately post-fixation. Functional outcome of elbow fracture from ring external fixation is comparable to ORIF due to better rehabilitation and lower complications. Ring external fixator in our patient achieved acceptable functional outcome and fracture alignment meanwhile the fracture was not complicated with common complications seen in ORIF. In conclusion, ring external fixator is as effective as ORIF in treating complex distal humeral fractures and should be considered for definitive fixation in such fractures

Introduction and Objective. Management of gap non-union of the tibia, the major weight bearing bone of the leg remains controversial. The different internal fixation techniques are often weighed down by relatively high complication rates that include fractures which fail to heal (non-union). Minimally invasive techniques with ring fixators and bone transport (distraction osteogenesis) have come into picture as an alternative allowing alignment and stabilization, avoiding a graduated approach. This study was focused on fractures that result in a gap non-union of > 6 cm. Ilizarov technique was employed for management of such non-unions in this case series. The Ilizarov apparatus consists of rings, rods and kirschner wires that encloses the limb as a cylinder and uses kirschner wires to create tension allowing early weight bearing and stimulating bone growth. Ilizarov technique works on the principle of distraction osteogenesis, that is, pulling apart of bone to stimulate new bone growth. Usually, 4–5 rings are used in the setup depending on fracture site and pattern for stable fixation. In this study, we demonstrate effective bone transport and formation of gap non-union more than 6 cm in 10 patients using only 3 rings construct Ilizarov apparatus. Materials and Methods. This case study was conducted at Dr. D. Y. Patil Medical Hospital, Navi Mumbai, Maharashtra, India. The study involved 10 patients with a non-union or gap > 6 cm after tibial fracture. 3 rings were used in the setup for the treatment of all the patients. Wires were passed percutaneously through the bone using a drill and the projecting ends of the wires were attached to the metal rings and tensioned to increase stability. The outcome of the study was measured using the Oxford Knee scoring system, Functional Mobility Scale, the American Foot and Ankle Score and Visual Analog Scale. Further, follow up of patients was done upto 2 years. Results. All the patients demonstrated good fixation as was assessed clinically and radiologically. 9 patients had a clinical score of > 65 which implied fair to excellent clinical rating. The patients showed good range of motion and were highly satisfied with the treatment as measured by different scoring parameters. Conclusions. In this case study, we demonstrate that the Ilizarov technique using 3 rings is equally effective in treating non-unions > 6 cm as when using 4–5 rings. Obtaining good clinical outcome and low complication rate in all 10 patients shows that this modified technique can be employed for patients with such difficulties in the future

Virtual mechanical testing is a method for measuring bone healing using finite element models built from computed tomography (CT) scans. Previously, we validated a dual-zone material model for ovine fracture callus that differentiates between mineralized woven bone and soft tissue based on radiodensity. 1. The objective of this study was to translate the dual-zone material model from sheep to two important clinical scenarios: human tibial fractures in early-stage healing and late-stage nonunions. CT scans for N = 19 tibial shaft fractures were obtained prospectively at 12 weeks post-op. A second group of N = 33 tibial nonunions with CT scans were retrospectively identified. The modeling techniques were based on our published method. 2. The dual-zone material model was implemented for humans by performing a cutoff sweep for both the 12-week and nonunion groups. Virtual torsional rigidity (VTR) was calculated as VTR = ML/φ [N-m. 2. /°], where M is the moment reaction, L is the diaphyseal segment length, and φ is the angle of twist. As the soft tissue cutoff was increased, the rigidity of the clinical fractures decreased and soft tissue located within the fracture gaps produced higher strains that are not predicted without the dual zone approach. The structural integrity of the nonunions varied, ranging from very low rigidities in atrophic cases to very high rigidities in highly calcified hypertrophic cases, even with dual-zone material modeling. Human fracture calluses are heterogeneous, comprising of woven bone and interstitial soft tissue. Use of a dual-zone callus material model may be instrumental in identifying delayed unions during early healing when callus formation is minimal and/or predominantly fibrous with little mineralization. ACKNOWLEDGEMENTS:. This work was supported by the National Science Foundation (NSF) grant CMMI-1943287

Fracture nonunion is a severe clinical problem for the patient, as well as for the clinician. About 5-20% of fractures does not heal properly after more than six months, with a 19% nonunion rate for tibia, 12% for femur and 13% for humerus, leading to patient morbidity, prolonged hospitalization, and high costs. The standard treatment with iliac crest-derived autologous bone filling the nonunion site may cause pain or hematoma to the patient, as well as major complications such as infection. The application of mesenchymal autologous cells (MSC) to improve bone formation calls for randomized, open, two-arm clinical studies to verify safety and efficacy. The ORTHOUNION * project (ORTHOpedic randomized clinical trial with expanded bone marrow MSC and bioceramics versus autograft in long bone nonUNIONs) is a multicentric, open, randomized, comparative phase II clinical trial, approved in the framework of the H2020 funding programme, under the coordination of Enrique Gòmez Barrena of the Hospital La Paz (Madrid, Spain). Starting from January 2017, patients with nonunion of femur, tibia or humerus have been actively enrolled in Spain, France, Germany, and Italy. The study protocol encompasses two experimental arms, i.e., autologous bone marrow-derived mesenchymal cells after expansion (‘high dose’ or ‘low dose’ MSC) combined to ceramic granules (MBCP™, Biomatlante), and iliac crest-derived autologous trabecular bone (ICAG) as active comparator arm, with a 2-year follow-up after surgery. Despite the COVID 19 pandemic with several lockdown periods in the four countries, the trial was continued, leading to 42 patients treated out of 51 included, with 11 receiving the bone graft (G1 arm), 15 the ‘high dose’ MSC (200x10. 6. , G2a arm) and 16 the ‘low dose’ MSC (100x10. 6. , G2b arm). The Rizzoli Orthopaedic Institute has functioned as coordinator of the Italian clinical centres (Bologna, Milano, Brescia) and the Biomedical Science and Technologies and Nanobiotechnology Lab of the RIT Dept. has enrolled six patients with the collaboration of the Rizzoli’ 3rd Orthopaedic and Traumatological Clinic prevalently Oncologic. Moreover, the IOR Lab has collected and analysed the blood samples from all the patients treated to monitor the changes of the bone turnover markers following the surgical treatment with G1, G2a or G2b protocols. The clinical and biochemical results of the study, still under evaluation, are presented. * ORTHOUNION Horizon 2020 GA 733288

Abstract. Objectives. Operative management of distal humerus fractures is challenging. In the past, plates were manually contoured intraoperatively, however this was associated with high rates of fixation failure, nonunion and metalwork removal. Anatomically pre-contoured distal humerus locking plates have since been developed. Owing to the rarity of distal humeral fractures, literature regarding outcomes of anatomically pre-contoured locking plates is lacking and patient numbers are often small. The purpose of this study is to investigate the outcomes of these patients. Methods. We retrospectively identified patients with distal humeral fractures treated at our institution from 2009–2018. Inclusion criteria were patients with a distal humeral fracture, who underwent two-column plate fixation with anatomically pre-contoured locking plates. Clinical records and radiographs were reviewed to elicit outcome measures, including range of motion, complications and reoperation rate. Results. We identified 50 patients with mean age of 55 years (range 17–96 years). Mean length of follow up was 5.2 years. AO fracture classification Type A occurred most frequently (46%), followed by Type B (22%) and Type C (32%). Low energy mechanisms of injury predominated in 72% of patients. Mean time from injury to fixation was seven days. Mean range of motion at the elbow was 13–123o postoperatively. The overall reoperation rate was 22%, the majority of which required subsequent removal of prominent metalwork (18%). The incidence of nonunion, heterotopic ossification, deep infection and neuropathy requiring decompression was 2% each. Fixation failure occurred in only one patient however the fracture went on to heal. Conclusions. Previously reported reoperation rates with manually contoured plates were as high as 44%, which is twice our reported rate. Modern locking plates are no longer subject to implant failure (previously 27% reported metalwork failure rate). Likewise, heterotopic ossification and non-union have also reduced, highlighting that modern plates have significantly improved overall patient outcomes. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Nonunions occur in situations with interrupted fracture healing process and indicate conditions where the fracture has no potential to heal without further intervention. Per definition, no healing is detected nine months post operation and there is no visible progress of healing over the last three months. The classification of nonunions as hypertrophic, oligotrophic, atrophic and pseudoarthosis, as well as aseptic or septic, identifies mechanical and biological requirements for fracture healing that have not been met. The overall treatment strategy comprises identification and elimination of the problems. However, current clinical methods to determine the state of healing are based on highly subjective radiographic evaluation or clinical examination. A data collection telemetric system for objective continuous measurement of the load carried by a bridging smart implant was developed to assess the mechanical stability and monitor bone healing in complicated fracture situations. The first results from a clinical trial show that the system is capable to offer early warning of nonunions or poor fracture healing. Nonunions are often multifactorial in nature and not just related to a biomechanical problem. Their successful treatment requires consideration of both biological and mechanical aspects. Disturbed vascularity and stability are the most important factors. Infection could be another complicating factor resulting in unpredictable long-time treatment. New technologies for monitoring of fracture healing in addition to radiographic evaluation and clinical examination seem to be promising for early detection of nonunions

Introduction and Objective. Nonunion is incomplete healing of fracture and fracture that lacks potential to heal without further intervention. Nonunion commonly presents with persistent pain, swelling, or instability. Those symptoms affect patient quality of life. It is known that using low intensity pulsed ultrasound (LIPUS) for fresh fractures promotes healing. However, effectiveness of LIPUS for nonunion is still controversial. If LIPUS is prove to be effective for healing nonunion, it can potentially provide an alternative to surgery. In addition, we can reduce costs by treating nonunion with LIPUS than performing revision surgery. Materials and Methods. The two authors carried out a systematic search of PubMed, Ovid MEDLINE, and the Cochrane Library. Meta-analysis of healing rate in nonunion and delayed union patients who underwent LIPUS was conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) instruction method using a random effects model. Results. The initial search identified 652 articles. Of these, 541 were excluded on the basis of the title because they were either a review paper or covered an unrelated topic. The abstracts of the remaining 111 articles were examined further. That review resulted in a sample of 12 articles. We performed a meta-analysis with a random effects model using Open Meta Analyst software. The result of pooled effect size of healing rate was 73.4% (95%CI: 65.3–81.6%). Due to the fact that nonunion lacks potential to heal without further intervention, we suggest that the therapeutic effect of 73.4% from LIPUS is sufficiently effective. As far as we know, there are no trials comparing the therapeutic effectiveness of surgery and LIPUS, so it cannot be said which is more advantageous. However, the healing rate of revision surgery was reported between 68–96%; therefore, our result is within that range. Thus, if surgery is difficult due to complications, we can recommend LIPUS. Conclusions. Meta-analysis of healing rate of nonunion treated by low-intensity pulsed ultrasound is 73.4%, which suggests sufficient therapeutic effectiveness. Furthermore, we can say that LIPUS may provide an alternative treatment for nonunion patients who cannot tolerate revision surgery due to complications

Objectives. The treatment of osteoporotic fractures is a major challenge, and the enhancement of healing is critical as a major goal in modern fracture management. Most osteoporotic fractures occur at the metaphyseal bone region but few models exist and the healing is still poorly understood. A systematic review was conducted to identify and analyse the appropriateness of current osteoporotic metaphyseal fracture animal models. Materials and Methods. A literature search was performed on the Pubmed, Embase, and Web of Science databases, and relevant articles were selected. A total of 19 studies were included. Information on the animal, induction of osteoporosis, fracture technique, site and fixation, healing results, and utility of the model were extracted. Results. Fracture techniques included drill hole defects (3 of 19), bone defects (3 of 19), partial osteotomy (1 of 19), and complete osteotomies (12 of 19). Drill hole models and incomplete osteotomy models are easy to perform and allow the study of therapeutic agents but do not represent the usual clinical setting. Additionally, biomaterials can be filled into drill hole defects for analysis. Complete osteotomy models are most commonly used and are best suited for the investigation of therapeutic drugs or noninvasive interventions. The metaphyseal defect models allow the study of biomaterials, which are associated with complex and comminuted osteoporotic fractures. Conclusion. For a clinically relevant model, we propose that an animal model should satisfy the following criteria to study osteoporotic fracture healing: 1) induction of osteoporosis, 2) complete osteotomy or defect at the metaphysis unilaterally, and 3) internal fixation. Cite this article: R. M. Y. Wong, M. H. V. Choy, M. C. M. Li, K-S. Leung, S. K-H. Chow, W-H. Cheung, J. C. Y. Cheng. A systematic review of current osteoporotic metaphyseal fracture animal models. Bone Joint Res 2018;7:6–11. DOI: 10.1302/2046-3758.71.BJR-2016-0334.R2

We present a novel use for an adult proximal humeral locking plate. In our case an 18-year-old female with cerebral palsy sustained a peri-prosthetic fracture of a blade plate previously inserted for a femoral osteotomy. Treatment was revision using a long proximal humeral locking plate. She had a successful outcome. We present the history and operative management. The female had a history of quadriplegic cerebral palsy, asthma, diabetes mellitus and congenital heart disease. She had a gastrostomy tube for enteral feeding. She was on nutritional supplements, baclofen, Omeprazole and movicol. She is looked after by her parents and requires a wheelchair for mobility. She is unable to communicate. Surgical History: Right adductor tenotomy, aged 11. Femoral Derotation Osteotomy & Dega Acetabular Osteotomy, aged 13. Right distal hamstring and knee capsule release, aged 14. Admitted to A&E (aged 18); unwitnessed fall. Painful, swollen, deformed thigh with crepitus. Xrays demonstrated peri- prosthetic fracture below blade plate. No specific equipment available to revise. Decision made to use PHILOS (Synthes, UK). GA, antibiotics, supine on table. Lateral approach. Plate removed after excising overgrown bone. Reduced and held. 10hole PHILOS applied. Near anatomical reduction. Secure fixation with locking screws proximally away from blade plate defect. Blood loss 800ml. 5 days in hospital. Sequential fracture clinic review. Wound healed well. Fracture healed on Xray at 11 months and discharged. To our knowledge this is the first reported use of a PHILOS plate for this specific fracture. The complexity of this case and underlying neurological disorder deemed long blade plate revision unsuitable. Fracture rates after femoral derotation osteotomies rare. 5/157 and 1/58 in the two largest studies to date. Conservative measures were the main recommendation. We have demonstrated a straightforward method for revision fixation with an excellent outcome. It would be recommended as an alternative to other surgeons in this position

Background. Comminuted fractures involving the tibia are associated with a high level of complications including delayed healing and non-union, in conjunction with dramatically increased healthcare costs. Certain clinicians utilise a Pixel Value Ratio (PRV) of 1 to indicate such fracture healing. The subjectivity of this method has led to mixed outcomes including regenerate fracture. The poor prognosis of complex load bearing fractures is accentuated by the fact that no quantitative gold standard currently exists to which clinicians can reference regarding the definition of a healed fracture. The aim of the current study is to use patient specific finite element analysis of complex tibial fractures treated with Ilizarov frames to demonstrate callus maturation and to determine the optimum frame removal time. Methods. 3 patients (2 males, 1 female) were analysed following presentation with complex tibial fractures treated with Ilizarov frames. Patient specific computational analysis was performed according to radiographic data, incorporating maturing material properties to analyse the callus response to weight bearing over the healing timeframe. Computational results were compared to the PVR method to evaluate its efficacy in determining the optimum Ilizarov frame removal time. Results. All fractures were observed to clinically heal at a mean of 25.4 (±2.404) weeks. Following computational analysis however, the mean optimum Ilizarov frame removal time was seen to be 23.5 (±2.323) weeks. When compared with the PVR method, the suggested removal time presented a mean PVR of 1.025 (±0.017). Conclusion. Computational models of patient specific tibial fractures has shown promising correlations with the PVR method and has shown efficacy in predicting callus strength and subsequent optimum frame removal time. Level of Evidence. Level 4

Early diagnosis of delayed- and non-union tibial fractures is difficult, but treatment options are available if timely data are available. Direct correlation between implant forces and healing status is difficult during stance phase loading due to soft tissue forces. This ongoing study seeks to find a minimal set of strain gauge sites needed to determine healing at any of several fracture sites, using isometric loading suitable for routine clinical usage. A series of instrumented tibial nails are being used to help determine whether an alternative technology can replace or augment existing routine methods for assessment of fracture healing. In a prior study, a single strain gauge positioned close to the fracture site had produced mixed results. In the current study, a TRIGEN META NAIL, 10mm OD x 380mm long, was instrumented with 8 gauged sites spiraled down the nail at 34mm axial and 120deg angular separation (Gen1), and loaded in a Sawbone model in offset axial compression, 3 point bending and torque. In order to gain early clinical results, and in a design informed by the Gen1 data, a set of instrumented nails have been made for an ovine wireless telemetry study (Gen3a), shortly to commence, in which the tibial nail has been over-gauged enabling multiple d.o.f. measurements to be made during gait, torque, axial compression and 3 point bending; the latter protocols offering more controlled patient postures. This study is to be followed by a similar human study (Gen3) involving five subjects (12 gauges per nail). Meanwhile, a parallel biomechanical study involving six nails with 20 gauges each is also planned. In the Gen1 study, the strains diminished with distance from the fracture site and with out-of-plane sites during bending. During torque, however, the response was much more uniform for all strain sites. Significant increases in strains due to both loading regimes were seen in the fractured case vs. an intact bone. Preliminary conclusions are that strains measured due to applied torque may offer a more sensitive and fracture site-independent means of assessing healing than induced bending. We now aim to confirm these observations in animal and human studies

Foreign-body reaction to polyglycolide (PGA) implants has been described in man. Many animal experiments have verified the mechanical properties of fixation devices made from PGA, but a significant foreign-body reaction has not been described. We studied the effect of PGA rods in 12 sheep with standardized osteochondral fractures of the medial femoral condyle fixed with uncoloured, self-reinforced PGA rods (Biofix). Radiographs were taken at intervals ranging from two weeks to two years, and the sheep were killed at intervals ranging from six to 24 months. All knees were examined histologically. Eleven of the 12 fractures healed radiologically and histologically. Moderate to severe osteolysis was seen at four to six weeks with maximum changes at 12 weeks in ten animals. Six knees showed fistula-like connections between the implant site and the joint space. Three developed synovitis, one with inflammatory changes involving the whole cartilage and one with destruction of the medial condyle. Although in our study osteochondral fractures fixed with PGA rods healed reliably, there were frequent, significant foreign-body reactions. Caution is needed when considering the use of PGA fixation devices in vulnerable regions such as the knee

Objectives. We investigated the effects on fracture healing of two up-regulators of inducible nitric oxide synthase (iNOS) in a rat model of an open femoral osteotomy: tadalafil, a phosphodiesterase inhibitor, and the recently reported nutraceutical, COMB-4 (consisting of L-citrulline, Paullinia cupana, ginger and muira puama), given orally for either 14 or 42 days. Materials and Methods. Unilateral femoral osteotomies were created in 58 male rats and fixed with an intramedullary compression nail. Rats were treated daily either with vehicle, tadalafil or COMB-4. Biomechanical testing of the healed fracture was performed on day 42. The volume, mineral content and bone density of the callus were measured by quantitative CT on days 14 and 42. Expression of iNOS was measured by immunohistochemistry. Results. When compared with the control group, the COMB-4 group exhibited 46% higher maximum strength (t-test, p = 0.029) and 92% higher stiffness (t-test, p = 0.023), but no significant changes were observed in the tadalafil group. At days 14 and 42, there was no significant difference between the three groups with respect to callus volume, mineral content and bone density. Expression of iNOS at day 14 was significantly higher in the COMB-4 group which, as expected, had returned to baseline levels at day 42. Conclusion. This study demonstrates an enhancement in fracture healing by an oral natural product known to augment iNOS expression. Cite this article: R. A. Rajfer, A. Kilic, A. S. Neviaser, L. M. Schulte, S. M. Hlaing, J. Landeros, M. G. Ferrini, E. Ebramzadeh, S-H. Park. Enhancement of fracture healing in the rat, modulated by compounds that stimulate inducible nitric oxide synthase: Acceleration of fracture healing via inducible nitric oxide synthase. Bone Joint Res 2017:6:–97. DOI: 10.1302/2046-3758.62.BJR-2016-0164.R2

Objectives

This study aimed to investigate the functional effects of microRNA (miR)-214-5p on osteoblastic cells, which might provide a potential role of miR-214-5p in bone fracture healing.

Objectives. Healing in cancellous metaphyseal bone might be different from midshaft fracture healing due to different access to mesenchymal stem cells, and because metaphyseal bone often heals without a cartilaginous phase. Inflammation plays an important role in the healing of a shaft fracture, but if metaphyseal injury is different, it is important to clarify if the role of inflammation is also different. The biology of fracture healing is also influenced by the degree of mechanical stability. It is unclear if inflammation interacts with stability-related factors. Methods. We investigated the role of inflammation in three different models: a metaphyseal screw pull-out, a shaft fracture with unstable nailing (IM-nail) and a stable external fixation (ExFix) model. For each, half of the animals received dexamethasone to reduce inflammation, and half received control injections. Mechanical and morphometric evaluation was used. Results. As expected, dexamethasone had a strong inhibitory effect on the healing of unstable, but also stable, shaft fractures. In contrast, dexamethasone tended to increase the mechanical strength of metaphyseal bone regenerated under stable conditions. Conclusions. It seems that dexamethasone has different effects on metaphyseal and diaphyseal bone healing. This could be explained by the different role of inflammation at different sites of injury. Cite this article: Bone Joint Res 2015;4:170–175

Objectives

This study tests the biomechanical properties of adjacent locked plate constructs in a femur model using Sawbones. Previous studies have described biomechanical behaviour related to inter-device distances. We hypothesise that a smaller lateral inter-plate distance will result in a biomechanically stronger construct, and that addition of an anterior plate will increase the overall strength of the construct.

This review is aimed at clinicians appraising preclinical trauma studies and researchers investigating compromised bone healing or novel treatments for fractures. It categorises the clinical scenarios of poor healing of fractures and attempts to match them with the appropriate animal models in the literature. We performed an extensive literature search of animal models of long bone fracture repair/nonunion and grouped the resulting studies according to the clinical scenario they were attempting to reflect; we then scrutinised them for their reliability and accuracy in reproducing that clinical scenario. Models for normal fracture repair (primary and secondary), delayed union, nonunion (atrophic and hypertrophic), segmental defects and fractures at risk of impaired healing were identified. Their accuracy in reflecting the clinical scenario ranged greatly and the reliability of reproducing the scenario ranged from 100% to 40%. It is vital to know the limitations and success of each model when considering its application

Objectives

To review the systemic impact of smoking on bone healing as evidenced within the orthopaedic literature.