Background. Fractures of the metatarsal bones are the most frequent fracture of the foot. Up to 70% involve the fifth metatarsal bone, of which approximately eighty percent are located proximally. Low-intensity pulsed ultrasound (LIPUS) has been shown to be a useful adjunct in the treatment of delayed fractures and non unions. However, there is no study looking at the success rate of LIPUS in fifth metatarsal fracture delayed unions. Objectives. The aim of our study was to investigate the use of LIPUS treatment for delayed union of fifth metatarsal fractures. Study Design & Methods. A retrospective review of patients who were treated with LIPUS following a delayed union of fifth metatarsal fracture was conducted over a three-year period (2013 – 2015). Delayed union was defined as lack of clinical and radiological evidence of union, bony continuity or bone reaction at the fracture site if 3 months has elapsed from the initial injury. Results. There were thirty patients (9 males, 21 females) in our cohort. The average age was 39.3 years. Type 2 fractures made up 43% of our cohort. Twenty-seven (90%) patients went on to progress to union clinically and radiologically following LIPUS treatment. Smoking (p=0.014) and size of fracture gap (p=0.045) were predictive of non-union. Conclusions. This is the first study looking at the use of LIPUS in the treatment of delayed union of fifth metatarsal fractures. We report a success rate of 90%. There is a role in the use of LIPUS in delayed union of fifth metatarsal fractures and can serve as an adjunct prior to consideration of surgery

Critical size bone defects are frequently caused by accidental trauma, oncologic surgery, and infection. Distraction osteogenesis (DO) is a useful technique to promote the repair of critical size bone defects. However, DO is usually a lengthy treatment, therefore accompanied with increased risks of complications such as infections and delayed union. Herein, we developed an innovative intramedullary biodegradable magnesium (Mg) nail to accelerate bone regeneration in critical size bone defect repair during DO. We observed that Mg nail induced almost 4-fold increase of new bone formation and over 5-fold of new vessel formation at 2 weeks after distraction. Mg nail upregulated the expression of calcitonin gene-related peptide (CGRP) in the new bone as compared with the DO alone group. We further revealed that blockade of the sensory nerve by overdose capsaicin blunted Mg nail enhanced critical size bone defect repair during the DO process. Moreover, inhibitors/antagonist of CGRP receptor, FAK, and VEGF receptor blocked the Mg nail stimulated vessel and bone formation. In summary, we revealed, for the first time, a CGRP-FAK-VEGF signaling axis linking sensory nerve and endothelial cells, which may be the main mechanism underlying Mg-enhanced critical size bone defect repair when combined with DO, suggesting a great potential of Mg implants in reducing DO treatment time for clinical applications

Autografts containing bone marrow (BM) are current gold standard in the treatment of critical size bone defects, delayed union and bone nonunion defects. Although reaching unprecedented healing rates in bone reconstruction, the mode of action and cell-cell interactions of bone marrow mononuclear cell (BM-MNC) populations have not yet been described. BM-MNCs consist of a heterogeneous mixture of hematopoetic and non-hematopoetic lineage fractions. Cell culture in a 3D environment is necessary to reflect on the complex mix of these adherend and non-adherend cells in a physiologically relevant context. Therefore, the main aim of this approach was to establish conditions for a stable 3D BM-MNC culture to assess cellular responses on fracture healing strategies. BM samples were obtained from residual material after surgery with positive ethical vote and informed consent of the patients. BM-MNCs were isolated by density gradient centrifugation, and cellular composition was determined by flow cytometry to obtain unbiased data sets on contained cell populations. Collagen from rat tail and human fibrin was used to facilitate a 3D culture environment for the BM-MNCs over a period of three days. Effects on cellular composition that could improve the regenerative potential of BM-MNCs within the BM autograft were assessed using flow cytometry. Cell-cell-interactions were visualized using confocal microscopy over a period of 24 hours. Cell localization and interaction partners were characterized using immunofluorescence labeled paraffin sectioning. Main BM-MNC populations like Monocytes, Macrophages, T cells and endothelial progenitor cells were determined and could be conserved in 3D culture over a period of three days. The 3D cultures will be further treated with already clinically available reagents that lead to effects even within a short-term exposure to stimulate angiogenic, osteogenic or immunomodulatory properties. These measures will help to ease the translation from “bench to bedside” into an intraoperative protocol in the end

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

The current procedures being applied in the clinical setting to address osteoporosis-related delayed union and nonunion bone fractures have been found to present mostly suboptimal outcomes. As a result, bone tissue engineering (BTE) solutions involving the development of implantable biomimetic scaffolds to replace damaged bone and support its regeneration are gaining interest. The piezoelectric properties of the bone tissue, which stem primarily from the significant presence of piezoelectric type I collagen fibrils in the tissue's extracellular matrix (ECM), play a key role in preserving the bone's homeostasis and provide integral assistance to the regeneration process. However, despite their significant potential, these properties of bone tend to be overlooked in most BTE-related studies. In order to bridge this gap in the literature, novel hydroxyapatite (HAp)-filled osteoinductive and piezoelectric poly(vinylidene fluoride-co-tetrafluoroethylene) (PVDF-TrFE) electrospun nanofibers were developed to replicate the bone's fibrous ECM composition and electrical features. Different HAp nanoparticle concentrations (1–10%, wt%) were tested to assess their effect on the physicochemical and biological properties of the resulting fibers. The fabricated scaffolds displayed biomimetic collagen fibril-like diameters, while also presenting mechanical features akin to type I collagen. The increase in HAp presence was found to enhance both surface and piezoelectric properties of the fibers, with an improvement in scaffold wettability and increase in β-phase nucleation (translating to increased piezoelectricity) being observed. The HAp-containing scaffolds also exhibited an augmented bioactivity, with a more comprehensive surface mineralization of the fibers being obtained for the scaffolds with the highest HAp concentrations. Improved osteogenic differentiation of seeded human mesenchymal stem/stromal cells was achieved with the addition of HAp, as confirmed by an increased ALP activity, calcium deposition and upregulated expression of key osteogenic markers. Overall, our findings highlight, for the first time, the potential of combining PVDF-TrFE and HAp to develop electroactive and osteoinductive nanofibers for BTE. Acknowledgements: The authors thank FCT for funding through the projects InSilico4OCReg (PTDC/EME-SIS/0838/2021), OptiBioScaffold (PTDC/EME-SIS/4446/2020) and BioMaterARISES (EXPL/CTM-CTM/0995/2021), the PhD scholarship (2022.10572.BD) and to the research institutions iBB (UIDB/04565/2020 and UIDP/04565/2020) and Associate Laboratory i4HB (LA/P/0140/2020)

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

Abstract. Objective. To compare the clinical and radiological outcome between less invasive stabilization system (LISS, Synthes, Paoli, PA.) and open reduction with internal fixation (ORIF) for the treatment of extraarticular proximal tibia fractures through the lateral approach. Background. Proximal tibial fractures present a difficult treatment challenge with historically high complication rates. ORIF has been in vogue for long time with good outcome. But these are associated with problems especially overlying skin conditions, delayed recovery and rehabilitation with limited functional outcome. LISS is an emerging procedure for the treatment of proximal tibial fractures. It preserves soft tissue and the periosteal circulation, which promotes fracture healing. Patients and methods. Thirty patients with closed proximal tibial fractures were included in this study. They were randomly divided into 2 groups. Group I (n=15) patients were treated by LISS and group II (n=15) by ORIF. Major characteristics of the two groups were similar in terms of age, sex, mode of injury, fracture location, and associated injuries. All patients were followed up at least 6 months. Results. In each group, 12 patients were united, 2 patients were non- united and one patient showed delayed union. The mean operative time in LISS patients was 79.3 min, while in ORIF patients; it was 122 min. All patients of LISS group were exposed to radiation, while only 40% of ORIF group were exposed. The mean time of union of LISS patients was 10.87weeks. While in ORIF patients, the mean time of union was 21.13 weeks. There was no significant difference between both groups regarding the postoperative complications. Functional outcome was satisfactory in both groups. Conclusion. LISS achieves comparable results with ORIF in extraarticular fractures of the proximal tibia. Although LISS potentially has the radiation hazard, it reduces the perioperative complications with a shortened operation time and minimal soft tissue dissection. 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

Introduction. This study aimed to compare MIPO and IMNr in the treatment of supracondylar femur fracture following TKA in respect of fracture healing, complications and functional results. Materials and Methods. A retrospective analysis was made of 32 supracondylar femur fractures classified according to the Rorabeck classification, comprising 20 cases treated with MIPO and 12 with IMNr. The two techniques were compared in respect of ROM, KSS, SF-12 scores, intraoperative blood loss, surgery time, and radiological examination findings. Results. No significant difference was determined between the two groups in respect of age, gender and fracture type, or in the median time to union (MIPO 4.3 months, IMNr 4.2 mths) (p >0.05). In the MIPO group, 2 patients had delayed union, so revision surgery was applied. The mean postoperative ROM was comparable between IMNr and MIPO (86.2 °vs 86 °, p > 0.05). The mean Knee Society Score (KSS) and SF-12 score did not differ between the IMN and MIPO groups. (p>0.05). Reduction quality in the sagittal plane was better in the MIPO group and no difference was determined in coronal alignment. Greater shortening of the lower extremity was seen in the IMNr group than in the MIPO group. (20.3 vs 9.3mm, p<0.05). Perioperative blood loss was greater (2 units vs.1.2 units) and mean operating time was longerin the MIPO group. (126.5 min vs 102.2 min, p<0.05). Conclusion. In patients with good bone stock, supracondylar femur fracture following TKA can be treated successfully with IMN or MIPO. IMN has the advantage of less blood loss and a shorter operating time. Reduction quality may be improved with the MIPO technique. Both surgery techniques can be successfully used by orthopaedic surgeons taking a case-by-case approach

Objectives. Pilon fractures represent one of the most surgically challenging fractures in orthopaedics. Different techniques exist for their management, with open reduction and internal fixation (ORIF) and External fixation (Ex-Fix) the most widely used. Whilst there is a plethora of data regarding these strategies for Pilon fractures as a whole, very limited data exists solely on the management of open Pilon fractures. This study aimed to elucidate how surgical management options can influence postoperative complications, and if this can influence future management protocols. Materials and methods. We conducted a search in PubMed, EMBASE and CENTRAL for postoperative complications and functional outcomes in open pilon fractures in those treated with Ex-Fix vs ORIF (PROSPERO-CRD42020184213). The postoperative complications measured included non-union, mal-union, delayed union, bone grafting, amputation, osteoarthritis, deep infection and superficial infection. Functional outcomes in the form of the AOFAS score was also measured where possible. We were able to carry out a meta-analysis for both deep infections and non-unions. Results. The search yielded 309 results and a total of 18 studies consisting of 484 patients were included. All fractures included were open, and consisted of 64 Gustilo-Anderson Type I, 148 Type II, 103 Type IIIa, 90 Type IIIb and 9 Type IIIc. 60 Type III fractures could not be further separated and 12 were ungraded. Both ORIF and Ex-Fix were found to have statistically similar AOFAS scores (p=0.682). For all included studies, the Ex-Fix group had significantly higher rates of superficial infections (p=0.001), non-unions (p=0.001), osteoarthritis (p=0.001) and bone grafting (p=0.001). The meta-analysis found no significant difference in non-union (pooled OR=0.25, 95% CI: 0.03 to 2.24, p = 0.44) or deep infection rates (pooled OR=1.35, 95% CI: 0.11 to 16.69, p = 0.12) between the ORIF and Ex-fix groups. Conclusion. Based on our study, while Ex-Fix and ORIF have similar functional outcomes, Ex-Fix appears to have a significantly higher risk of postoperative complications which must be considered by surgeons when choosing surgical management options. Further research, ideally in a randomised control trial format, is required to definitively demonstrate ORIF superiority in the management of open pilon fractures

Introduction. Simultaneous correction of knee varus malalignment with medial open wedge high tibial osteotomy (MOWHTO) combined with anterior cruciate ligament (ACL) surgery aims to address symptomatic unicompartmental osteoarthritis in addition to restore knee stability in order to improve outcomes. The aim of this study is to present at least 5 years results of 32 patients who underwent simultaneous knee realignment osteotomy with ACL surgery. Methods. Patients with symptomatic instability due to chronic ACL deficiency or failed previous ACL surgery together with a varus malalignment of ≥6°, previous medial meniscectomy and symptomatic medial compartment pain who were treated with MOWHTO combined with ACL surgery were enrolled. ACL surgery was performed with the anatomical single bundle all-inside technique using TightRope. ®. RT (Arthrex, Naples, FL, USA) and MOWHTO using TomoFix. ®. medial high tibia plate (DePuy Synthes, Raynham, MA, USA) in all cases. Patients were evaluated preoperatively and at 6 months, 12 months and annually postoperatively using the Knee Injury and Osteoarthritis Outcome Score (KOOS), Oxford Knee Score (OKS) and Euroqol's Visual Analogue Score (VAS) for pain. Results. 32 patients (22 men and 10 women) with a mean age of 41.2 years and mean BMI of 28.6 kg/m. 2. , underwent the combined procedures. Tibiofemoral neutral re-alignment was achieved in all patients with HTO. Complete subjective and objective scores have been obtained in 84.4% of patients with at least 5 years of follow-up (mean 8.7 years). An improvement in total KOOS of 27.1 points (p<0.003), OKS of 15.1 (p<0.003) and VAS for pain of 24.7 points (p<0.001) were detected. No ACL reconstruction failure was noted. Complications consisted of one superficial wound infection and one delayed union. Plate removal was needed in 20 (62.5%) patients due to pes anserinus pain. Conclusions. Simultaneous restoration of coronal knee axis by applying HTO and stability by ACL reconstruction/revision were reported to offer excellent improvement in early outcomes in patients with ACL rupture and symptomatic unicompartmental osteoarthritis. The combined procedure requires careful pre-operative planning and is therefore technically challenging. However, by restoring the neutral axis and providing stability, it represents a good joint preserving alternative to arthroplasty for active middle-aged patients

INTRODUCTION. Intramedullary nail fixation has been used for successful treatment of long bone fracture such as humerus, tibia and femur. We look at the experience of our trauma unit in treating long bone fracture using the AO approved Expert femoral/tibial nail and proximal femoral nail antirotation (PFNA). We look at the union and complication rates in patients treated with AO approved nailing system for pertrochanteric, femoral and tibial shaft fracture. METHODS. We carried out retrospective case notes review of patients that underwent femoral and tibial nailing during the period of study- October 2007 to August 2009. All patients were treated using the AO approved nailing system. We identified all trauma patients that underwent femoral and tibial nailing through the trauma register. Further information was then obtained by going through medical notes and reviewing all followed-up X-rays stored within the online radiology system. RESULTS. 149 patients, 85 male and 64 female were included into the study. 150 procedures were carried out during period of study as 1 patient underwent conversion of lateral entry femoral nail to PFNA due to refracture. Patients' age ranged from 14-96 with mean of 55. 140 patients had isolated long bone fracture (either femur or tibia) compared to 9 patients with multiple bone fractures. Our unit performed 64 Expert tibial nail, 36 PFNA, 31 Expert lateral entry femoral nail and 19 Expert retrograde femoral nail during period of study. 13 patients treated with intramedullary nail sustained open fracture, 9 of them were compound tibial fracture compared to 4 compound femoral fractures. All patients were followed-up between 2 to 24 months or until death. 9 out of 17 patients that died in this study had diagnosis of tumour. Complication rates were 17% for Expert tibial nail (1 patient with valgus deformity, peroneal nerve palsy and delayed union, 3 with delayed union, 4 with broken locking screw, 2 with wound infection and 1 with abscess over wound site), 4% for lateral/retrograde femoral nail (1 each for pulmonary embolism and broken locking screw) and 4% for PFNA (1 each for delayed union and deep vein thrombosis). The overall complication rates were 10% from this study. DISCUSSION & CONCLUSIONS. We conclude that the AO approved nailing system used for treating pertrochanteric, femoral and tibial fractures were effective with high union rate. The overall complication rates were 10% from this study. Complication rates for tibial nail were as high as 17% compared to 4% for femoral nail or PFNA. The complication rates for PFNA in our study were lower compared to 29% in PFN that was reported in one literature

The current treatment for osteoporosis such as bisphosphonates inhibits the catabolic activity of osteoclasts and subsequent bone resorption, but does not increase bone formation. There is therefore interest in using anabolic factors such as stem cells to augment fracture repair. The poor bone formation in postmenopausal women could be due to poor retention and function of Mesenchymal stem cells (MSCs) resulting into delayed unions. Another factor associated with fracture healing is the retention and migration of stem cells to the site of injury (1–3). The aim of this study was to isolate stem cells from osteopenic rats and investigate and compare the CD marker expression, proliferation, migration, osteogenic and adipogenic differentiation. The hypothesis of this study is that the migration of MSCs from young, adult and ovariectomised (OVX) rats will have different proliferation, differentiation and migratory abilities. Ovariectomy was performed in 6–9 month old Wistar rats and osteopenia developed over a 4 month post-op period. MSCs were harvested from the femora of young, adult and osteopenic Wistar rats. Proliferation of the these MSCs from the three group of rats was measured using Alamar blue, osteogenic differentiation was measured using ALP expression at day 0, 7, 14 and 21 and alizarin red at day 21. Adipogenic differentiation was measured at day 7, 14 and 21 using Oil red O. Cells were incubated in Boyden chambers to quantify their migration towards SDF1. For analysis, the number of cells migrating across the membrane was expressed as a percentage of the cells remaining on the upper membrane surface. Data was analysed using a Student t-test where p values < 0.05 were considered significant. The stem cells from all 3 groups of rats expressed on average the same amount of CD29 (>90%), CD90 (>96%), CD34 (<5%) and CD45 (approx 10%). The proliferation rate measured by Alamar blue normalised against DNA was also similar at day 3, 7, 10 and 14. However, interestingly the migration and differentiation ability was significantly different between the MSCs from the 3 groups of rats. The young MSCs were not only better at differentiating into bone and fat as well, but they also migrated significantly more towards SDF1. The migration of SDF-1 doubled with young rats compared to the adult rats (p = 0.023) and it was four times higher when compared to cells isolated from OVX rats (p = 0.013). MSCs from OVX rats are similar to MSCs from young rats. However when induced to turn into bone, fat and migrate towards SDF1, young MSCs are significantly more responsive than MSCs from OVX and adult control rats. The poor homing ability and differentiation of the stem cells and their retention may result in a reduction in bone formation leading to delayed union in fractures of osteoporotic patients(4)

Bone allograft is the most widely accepted approach in treating patients suffering from large segmental bone defect regardless of the advancement of synthetic bone substitutes. However, the long-term complications of allograft application in term of delayed union and nonunion were reported due to the stringent sterilization process. Our previous studies demonstrated that the incorporation of magnesium ions (Mg2+) into biomaterials could significantly promote the gene up-regulation of osteoblasts and new bone formation in animal model. Hence, our group has proposed to establish an Mg2+ enriched tissue microenvironment onto bone allograft so as to enhance the bone healing. The decellularization and gamma irradiation process were performed on bovine bone allograft and followed by magnesium plasma treatment. To evaluate the biocompatibility and bioactivity, materials characterizations, in vitro and in vivo studies were conducted, respectively. Mg composite layer on bone surface ranged from 500nm to ∼800nm thick. The cell viability on magnesium enriched allograft was significantly higher than that of the control. The ALP gene expression of hTMSCs in the group of PIII&D treated samples was highly up-regulated. The bone regeneration ability of Mg modified bone allograft implanted in animal model was significantly superior than the control after 2-month post-operation

External fixation of distal tibial fractures is often associated with delayed union. We have investigated whether union can be enhanced by using recombinant bone morphogenetic protein-7 (rhBMP-7). Osteoinduction with rhBMP-7 and bovine collagen was used in 20 patients with distal tibial fractures which had been treated by external fixation (BMP group). Healing of the fracture was compared with that of 20 matched patients in whom treatment was similar except that rhBMP-7 was not used. Significantly more fractures had healed by 16 (p = 0.039) and 20 weeks (p = 0.022) in the BMP group compared with the matched group. The mean time to union (p = 0.002), the duration of absence from work (p = 0.018) and the time for which external fixation was required (p = 0.037) were significantly shorter in the BMP group than in the matched group. Secondary intervention due to delayed healing was required in two patients in the BMP group and seven in the matched group. RhBMP-7 can enhance the union of distal tibial fractures treated by external fixation

Introduction. The treatment of distal femoral fractures has undergone several changes during the past century, from non-operative techniques to more recently minimally-invasive internal fixation. The Less Invasive Stabilisation System (LISS) is an internal fixation plate that combines closed fixation of the distal femur using an anatomically pre-contoured plate with locked unicortical screws. Study aim. The purpose of this multicentre study was to review the use of the LISS plate in three regional centres with respect to fracture healing between different severities of fractures. Materials and methods. Patients treated with a LISS plate for a distal femoral fracture (AO/OTA Type 33A1 to 33C3) between 1st January 2004 and 1st June 2008 were recruited. Demographic data plus mechanism of injury, type of fracture, injury severity scores (ISS) and complications were documented. Subgroup statistical analysis using SPSS for Windows v. 17 was conducted to determine differences in the mean ISS, operating time, length of hospitalisation and ultimately, the time taken for union between groups of different fracture severities (Type 33A vs. Type 33C fractures). A P value of less than 0.05 was considered to be significant. Results. Across the 3 regional centres, a total of 88 patients presented with a distal femoral fracture, of which 44 were treated with a LISS plate. The mean age of the patients was 66.1 (range 9 - 99), with 15 males and 29 females. There were 14 Type 33A1, 13 Type 33A2, 6 Type 33A3, 1 Type 33B2, 1 Type 33C1, 5 Type 33C2 and 4 Type 33C3 fractures. Union was achieved within an average of 14.7 weeks (range 8 - 25) in 33 cases. Five cases exhibited non-union and were managed by a retrograde nail or another locking compression plate. Six cases developed delayed union. Subgroup analysis revealed that patients with Type 33C (n = 10) fractures presented with a significantly greater mean ISS score (12.7 vs. 10.0, p = 0.031), endured longer operating time (203.7 minutes vs. 125.8 minutes, p = 0.016) and spent longer in hospital compared to Type 33A (n = 33) fractures (35.3 days vs. 12.5 days, p = 0.004). However, no difference in the mean time for radiological union between the groups was observed (16.4 weeks vs. 13.6 weeks, p = 0.058). Discussion. We observed an overall success rate of 75% (33 out of 44 cases) as fractures reached radiological union within an average of 14.7 weeks. Interestingly, despite a greater mean ISS score and operating time among Type 33C fractures, the subgroup analysis confirmed that the LISS plate is a robust treatment option across all fracture severities, as this did not translate as longer time to union compared to Type 33A fractures. However, there were 5 cases of non-union and 6 cases of delayed union in our series. These may have arisen due to lack of precision in surgical technique, as we observed 8 cases of suboptimal implant positioning. Three cases involved distal screws lacking contact with the medial cortex of the femur. Overall, our data suggest a favourable outcome for the LISS plate in the treatment of distal femoral fractures

Background. Intramedullary nailing is a widely accepted treatment method for femoral fractures. Failure of locking screws is often a threatening complication, particularly on comminuted fractures. For comminuted fractures, the locking nails are load-bearing devices. The load transfer between fractured fragments is made through especially the locking screws for these load bearing situations. Nonunion, malunion, delayed union, shortening, and nail migration are the expected results if early failure of locking screws is present with comminuted fractures. In this study our aim was to compare the bending resistance of titanium and stainless steel locking screws. Methods. We tested 60 locking screws in six groups (titanium, stainless steel, unthreaded, low threaded and high threaded) in a steel tube that has 30 mm inner diameter, which imitates the lesser trochanter level. We determined the yield points at three-point bending tests that permanent deformation started in the locking screws using an axial compression testing machine. Results. The three-point bending resistance of 5 mm low threaded titanium locking screws (bending at 1413 N loading) was 46.5 % less than the three-point bending resistance of 5 mm low threaded stainless steel locking screws (bending at 2171 N loading) (p < 0.001). Five mm stainless steel locking screws are 29–57 % more resistant to three-point bending deformation than titanium ones. Conclusions. Therefore, stainless steel locking screws instead of titanium ones must be preferred in comminuted femur shaft fractures. In intramedullary nailing of comminuted or long oblique femur fractures, a locking screw should be 5 mm low threaded or unthreaded stainless steel or 5 mm unthreadedtitanium. Five mm high threaded titanium or stainless steel screws must not ever be used as a locking screw. Level of Evidence. 5. Disclosure. Authors declare that there is no conflict of interest related to the present study

Background. Bothlimited-contact dynamic compression plate (LC-DCP) and locking compression plate (LCP) systems were designed to provide enhanced bone healing and to improve stability at fracture site. However, implant failure, delayed union, nonunion and instability are still frequently encountered complications. The purpose of this study was to determine the biomechanical characteristics of a novel persistent compression dynamic plate (PCDP) which provides a persistent compression to fracture edges, and to compare the biomechanical properties of such a novel plate with the commonly used LCP. Methods. The novel persistent compression dynamic plate (PCDP) system is composed of a body, an inner compression spring and a distal mobile component. The body (proximal part) contains an adjustable screw and the distal part of the dynamic system can slide inside the body through a special tube. 12 (saw bone) artificial femoral bones were used. Transverse distal shaft fracture was created in all the saw bones at the same level, 6 femurs were fixed using the novel PCDP, whereas the other 6 femurs were fixed using the well-known LCP. All samples had undergone a nondestructive repetitive different forces (axial compression, bending and torsion), to evaluate the biomechanical differences between the two plating systems. Results. Under axial load the mean stiffness value was 439,0 N/mm for the PCDP and 158,9 N/mm for the LCP. There was nosignificant difference in A-P (anteroposterior) ve P-A (posteroanterior) bending stiffness values between PCDP and LCP, P=0.37 and P=0.80 respectively. However LCP provided significantly stiffer fixation in medial and lateral bending tests than PCDP (P=0.037) and (P=0.016), respectively. But no significant difference was detected between the two plating system in the torsional stiffness P=0.15. Conclusion. These results do not show any significant biomechanical difference in the applied torsional and bending stresses between LCP and PCDP. However the remarkably increased persistent compression effect of the PCDP created a considerable stress on fracture edges which may accelerate bone healing. Level of Evidence. Level 5

There is increasing interest in using anabolic factors such as stem cells to augment fragility fracture repair. One of the factors associated with fracture healing is the retention and migration of stem cells to the site of injury (1–3). The aim of this study was to isolate stem cells from osteopenic rats and investigate and compare the CD marker expression, proliferation, migration, osteogenic and adipogenic differentiation. The hypothesis of this study is that the migration of MSCs from young, adult and ovariectomised (OVX) rats will have different proliferation, differentiation and migratory abilities. CD marker expression of MSCs from young, adult and osteopenic rats was measured using flow cytometry. Proliferation, osteogenic differentiation and adipogenic differentiation was measured using Alamar Blue, ALP expression and Alizari n Red and quantitative Oil red O respectively. Cells were incubated in Boyden chambers to quantify their migration towards SDF1. Data was analysed using a Student t-test where p values < 0.05 were considered significant. MSCs from all 3 groups of rats had similar proliferation and expression of CD29(>90%), CD90(>96%), CD34(<5%) and CD45(approx 10%). The proliferation rate was also similar. However, interestingly the migration and differentiation ability was significantly different between the MSCs from the 3 groups of rats. The young MSCs were not only better at differentiating into bone and fat, but they also migrated significantly more towards SDF1. MSCs from OVX rats are similar to MSCs from young rats. However when induced to turn into bone, fat and migrate towards SDF1, young MSCs are significantly more responsive than MSCs from OVX and adult control rats. The poor homing ability and differentiation of the stem cells and their retention may result in a reduction in bone formation leading to delayed union in fractures of osteoporotic patients(4)

We used interconnected porous calcium hydroxyapatite ceramic to bridge a rabbit ulnar defect. Two weeks after inducing the defect we percutaneously injected rabbit bone marrow-derived mesenchymal stromal cells labelled with ferumoxide. The contribution of an external magnetic targeting system to attract these cells into the ceramic and their effect on subsequent bone formation were evaluated. This technique significantly facilitated the infiltration of ferumoxide-labelled cells into ceramic and significantly contributed to the enhancement of bone formation even in the chronic phase. As such, it is potentially of clinical use to treat fractures, bone defects, delayed union and nonunion

Displaced proximal Humeral fractures at Inverclyde Royal Hospital prior to 2008 were previously treated with the antegrade Acumed Polaris Proximal Humeral, predominantly in 2 part fractures. The Philos plate was introduced in 2008, initially being used to treat select non unions, and then expanded to acute fractures. The aim of this study was to assess time to union and complications in the lower volume District General setting comparing to published outcomes. From February 2008 – January 2011, 20 patients were identified. Age range 49–75 (mean 61.2) years, 8 male; 12 female. Left 9, Right 11 Neers 2 part 35%; 3 35%; 4 30%. 16 (80%) were performed in acute fractures with 4 for non-unions, 3 of which were previous polaris nail fixations. 2 patients were lost to follow up after 6/52 but were progressing well. Union was confirmed radiologically and clinically in all but 2 remaining patients (10%), one of whom suffered a significant complication of plate fracture, the second treated with revision for painful non union. 2 other significant complications were observed: transient axillary nerve palsy and deep infection. Both of these patients recovered with delayed union observed in the infection case (52 weeks). Time to union range was 8–52 weeks (mean 17.1). The literature shows a high failure rate of up to 45% with intramedullary nail fixation and limited predominantly to 2 part fractures with risk of damage to the rotator cuff. This study shows a satisfactory union rate using the Philos of 90% with only 3 (15%) requiring further surgery for non-union, plate fracture and infection. 3 and 4 part fractures composed 65% of case load. Early results indicate satisfactory outcomes compared to current published literature