Experimental Validation of the Radiographic Union Score for Tibial Fractures (RUST) Using Micro-Computed Tomography Scanning and Biomechanical Testing in an in-Vivo Rat Model

Transcutaneous CO2 application combined with low-intensity pulsed ultrasound accelerates bone fracture healing in rats

BACKGROUND

Low-intensity pulsed ultrasound (LIPUS) is a non-invasive therapy that accelerates fracture healing. As a new treatment method for fracture, we recently reported that the transcutaneous application of CO2 accelerated fracture healing in association with promoting angiogenesis, blood flow, and endochondral ossification. We hypothesized that transcutaneous CO2 application, combined with LIPUS, would promote bone fracture healing more than the single treatment with either of them.

METHODS

Femoral shaft fractures were produced in 12-week-old rats. Animals were randomly divided into four groups: the combination of CO2 and LIPUS, CO2, LIPUS, and control groups. As the transcutaneous CO2 application, the limb was sealed in a CO2-filled bag after applying hydrogel that promotes CO2 absorption. Transcutaneous CO2 application and LIPUS irradiation were performed for 20 min/day, 5 days/week. At weeks 1, 2, 3, and 4 after the fractures, we assessed the fracture healing process using radiography, histology, immunohistochemistry, real-time PCR, and biomechanical assessment.

RESULTS

The fracture healing score using radiographs in the combination group was significantly higher than that in the control group at all time points and those in both the LIPUS and CO2 groups at weeks 1, 2, and 4. The degree of bone fracture healing in the histological assessment was significantly higher in the combination group than that in the control group at weeks 2, 3, and 4. In the immunohistochemical assessment, the vascular densities of CD31- and endomucin-positive microvessels in the combination group were significantly higher than those in the control and LIPUS groups at week 2. In the gene expression assessment, significant upregulation of runt-related transcription factor 2 (Runx2) and vascular endothelial growth factor (VEGF) was detected in the combination group compared to the LIPUS and CO2 monotherapy groups. In the biomechanical assessment, the ultimate stress was significantly higher in the combination group than in the LIPUS and CO2 groups.

CONCLUSION

The combination therapy of transcutaneous CO2 application and LIPUS had a superior effect in promoting fracture healing through the promotion of angiogenesis and osteoblast differentiation compared to monotherapy.

Experimental Study on Rats with Critical-Size Bone Defects Comparing Effects of Autologous Bone Graft, Equine Bone Substitute Bio-Gen® Alone or in Association with Platelet-Rich Fibrin (PRF)

BACKGROUND

A critical-sized bone defect (CsBD) is considered one that will not heal spontaneously and requires reconstruction. This study aims to compare the results of using different bone reconstructive techniques and to study the potential of platelet-rich fibrin (PRF) to enhance the healing properties of a bone substitute (BS).

METHODS

In this experimental study on rats, the treatment of critical-sized bone defects was carried out by analysing four groups: a control group in which the bone defect was left empty; a group treated with Bio-Gen®; another group in which the defect was treated with PRF in combination with Bio-Gen®; and the last that was treated with autologous bone graft (ABG). The defects were evaluated by microcomputed tomography (µCT) and then histomorphometrically.

RESULTS

From both the histological and imagistic point of view, the best results were registered in the ABG group, followed by the group treated with Bio-Gen® with PRF, Bio-Gen® group, and control group, with statistically significant differences.

CONCLUSIONS

A 5 mm defect in the rat radius can be considered critical. ABG showed the best results in treating the bone defect. PRF significantly enhanced the efficacy of Bio-Gen®.

In Vivo Investigation of 3D-Printed Calcium Magnesium Phosphate Wedges in Partial Load Defects

Bone substitutes are ideally biocompatible, osteoconductive, degradable and defect-specific and provide mechanical stability. Magnesium phosphate cements (MPCs) offer high initial stability and faster degradation compared to the well-researched calcium phosphate cements (CPCs). Calcium magnesium phosphate cements (CMPCs) should combine the properties of both and have so far shown promising results. The present study aimed to investigate and compare the degradation and osseointegration behavior of 3D powder-printed wedges of CMPC and MPC in vivo. The wedges were post-treated with phosphoric acid (CMPC) and diammonium hydrogen phosphate (MPC) and implanted in a partially loaded defect model in the proximal rabbit tibia. The evaluation included clinical, in vivo µ-CT and X-ray examinations, histology, energy dispersive X-ray analysis (EDX) and scanning electron microscopy (SEM) for up to 30 weeks. SEM analysis revealed a zone of unreacted material in the MPC, indicating the need to optimize the manufacturing and post-treatment process. However, all materials showed excellent biocompatibility and mechanical stability. After 24 weeks, they were almost completely degraded. The slower degradation rate of the CMPC corresponded more favorably to the bone growth rate compared to the MPC. Due to the promising results of the CMPC in this study, it should be further investigated, for example in defect models with higher load.

Application of the Modified RUST Score in Tibial Bone Transport and Factors Associated with Docking Site Complications

Aim

Reconstruction of segmental bone defects with bone transport is a well-established treatment. Mechanical complications at the docking site after frame removal are common. These complications include malunion, non-union, axial deviation and refracture. A simple tool to assess the healing of the docking site is currently lacking. The aim of this study is to evaluate the use of the modified RUST (mRUST) score in the setting of bone transport and to identify factors associated with an increased risk of docking site complications.

Methods

This retrospective study was conducted at a single tertiary centre in South Africa, included 24 patients with a tibial bone defect treated with bone transport and a circular frame between 2014 and 2023. Demographic data, clinical and bone transport characteristics were recorded. Mechanical complications, such as fracture, non-union, any angulation >5°, shortening >5 mm, or any other complication requiring reoperation, were recorded. The mRUST was adapted as a ratio for the purpose of this study to overcome the common occurrence of cortices being obscured by the frame. The mRUST ratio was applied before and after frame removal for each patient by three appraisers. Comparison between the groups with and without complications was performed regarding bone transport characteristics, docking site configuration and mRUST ratio. The correlation of the score between radiographs before and after frame removal was assessed. The inter-rater reliability of the mRUST was analysed using Fleiss Kappa statistics for each cortex individually and the intraclass correlation coefficient (ICC) for the mRUST ratio.

Results

In this study, 20 men and 4 women with a median age of 26 years were included. The overall rate of mechanical complications after frame removal was 21.7%. Complications were all related to the docking site, with two angulations, two fractures and one non-union. Demographics, bone transport characteristics and mRUST ratio before and after frame removal were similar between the two groups. Regarding the configuration of the docking site, an angle of 45° or more between the bone surfaces was associated with the occurrence of mechanical complications (p < 0.001). The correlation of the mean mRUST ratio before and after frame removal showed a moderate relationship, with a Spearman correlation coefficient of 0.50 (p-value 0.13). The inter-rater reliability of the mRUST was "fair" (kappa 0.21-0.40) for the scoring of individual cortices, except for one score which was "slight" (kappa 0.00-0.20). The ICC of the mRUST ratio was 0.662 on radiographs with the frame, and 0.759 after frame removal.

Conclusion

This study did not find the mRUST or mRUST ratio useful in assessing the healing of the docking site to decide on the best time to remove the frame. However, a notable finding was that the shape and orientation of the bone ends meeting at the docking site might well be relevant to decrease complication rates. If the angle between the bony surfaces is 45° or more, it may be associated with an increased risk of complications. It may be worthwhile considering reshaping these bone ends at the time of debridement or formal docking procedure to be more collinear, in order to reduce the potential for mechanical complications such as non-union, axial deviation or refracture at the docking site.

How to cite this article

Kummer A, Nieuwoudt L, Marais LC. Application of the Modified RUST Score in Tibial Bone Transport and Factors Associated with Docking Site Complications. Strategies Trauma Limb Reconstr 2024;19(2):73-81.

Unplanned reoperation is common following intramedullary nailing of open femoral shaft fractures: A retrospective review

Background

The objective of this study is to investigate the incidence of unplanned reoperation, nonunion and infection following open femoral shaft fractures treated with an intramedullary nail and correlate these occurrences with patient variables and injury characteristics.

Methods

A retrospective review of open femur fractures from a level 1 trauma center between 2012 and 2020 was performed. Ninety-five patients who sustained an open femur fracture, were treated definitively with an intramedullary nail, and had at least 3 months of follow-up were included in the analysis for surgical site infection. Seventy-three of these patients had at least one year of follow-up. After excluding planned bone grafting for segmental defects, 67 patients were included in the analysis of unplanned reoperation.

Results

The rate of unplanned reoperation was 31.3 %, with 57 % of these operations occurring to address nonunion. The overall nonunion rate was 18 %. In patients who did not require reoperation to obtain union, the median time to union for the cohort was 6 months, with an interquartile range of 3-7.5 months. Post-operative surgical site infection occurred in 11.6 % of patients.

Conclusions

In conclusion, unplanned reoperation following intramedullary nailing of open femur fractures occurs in nearly 1/3rd of patients and the rates of nonunion and surgical site infection may be higher than previously reported in the literature. Reoperation most closely correlates with the OTA Open Fracture Classification System. Patients with open femur fractures should be counseled that reoperation is often required to obtain fracture union, with soft tissue and fracture injury severity predicting complications.

Novel approaches to correlate computerized tomography imaging of bone fracture callus to callus structural mechanics

Estimating the mechanical properties of bone in vivo without destructive testing would be useful for research and clinical orthopedic applications. Micro-computerized tomography (μCT) imaging can provide quantitative, high-resolution 3D representations of bone morphology and is generally the basis from which bone mechanical properties are non-destructively estimated. The goal of this study was to develop metrics using qualitative and quantitative aspects of bone microarchitecture derived from μCT imaging to estimate the mechanical integrity of bone fracture calluses. Mechanical testing data (peak torque) and μCT image data from 12 rat femur fractures were collected at 4 weeks after fracture. MATLAB was used to analyze the callus μCT imaging data which were then correlated to the empirically determined peak torque of the callus. One metric correlated Z-rays, linear contiguities of voxels running parallel to the neutral axis of the femur and through the fracture callus, to peak torque. Other metrics were based on voxel linkage values (LVs), which is a novel measurement defined by the number of voxels surrounding a given voxel (ranging from 1 to 27) that are all above a specified threshold. Linkage values were utilized to segment the callus and compute healing scores (termed eRUST) based on the modified Radiographic Union Score for Tibial fractures (mRUST). Linkage values were also used to calculate linked bone areas (LBAs). All metrics positively correlated with peak torque, yielding correlations of determination (R2) of 0.863 for eRUST, 0.792 for Z-ray scoring, and 0.764 for a normalized Linked Bone Area metric. These novel metrics appear to be promising approaches for extrapolating fracture callus structural properties from bone microarchitecture using objective analytical methods and without resorting to computationally complex finite element analyses.

Intramedullary Fixation for Pediatric Femoral Nonunion in Low- and Middle-Income Countries

BACKGROUND

Pediatric femoral shaft nonunion after use of a plate or intramedullary nail (IMN) is uncommon in the United States. In low and middle-income countries, as defined by The World Bank, these complications may occur with greater frequency. We assessed the rates of union and painless weight-bearing after IMN fixation of pediatric femoral shaft nonunion in lower-resource settings.

METHODS

We queried the SIGN (Surgical Implant Generation Network) Fracture Care International online database to identify all pediatric femoral shaft nonunions that had occurred since 2003 and had ≥3 months of follow-up after their treatment; our query identified 85 fractures in 83 patients. We defined nonunion as failure of initial instrumentation >90 days following its placement, lack of radiographic progression on radiographs made >3 months apart, or the absence of signs of radiographic healing >6 months after initial instrumentation. We evaluated the most recent follow-up radiograph to determine a Radiographic Union Scale in Tibial fractures (RUST) score. We also recorded rates of painless full weight-bearing as assessed by the treating surgeon.

RESULTS

Fifty-seven patients with pediatric femoral shaft nonunions (including 42 male and 15 female patients from 18 countries) were included. The average age (and standard deviation) at the time of revision surgery was 13.8 ± 3.0 years (range, 6 to 17 years). The median duration of follow-up was 67 weeks (range, 13 weeks to 7.7 years). The initial instrumentation that went on to implant failure included plate constructs (56%), non-SIGN IMNs (40%), and SIGN IMNs (4%). At the time of the latest follow-up, 52 patients (91%) had a RUST score of ≥10 and 51 (89%) had painless full weight-bearing. No patient had radiographic evidence of femoral head osteonecrosis at the time of complete fracture-healing or the latest follow-up.

CONCLUSIONS

Pediatric femoral shaft nonunion can occur after both plate and IMN fixation in low and middle-income countries. IMN fixation is an effective and safe treatment for these injuries.

LEVEL OF EVIDENCE

Therapeutic Level IV . See Instructions for Authors for a complete description of levels of evidence.

Lower-limb internal loading and potential consequences for fracture healing

Introduction: Mechanical loading is known to determine the course of bone fracture healing. We hypothesise that lower limb long bone loading differs with knee flexion angle during walking and frontal knee alignment, which affects fracture healing success. Materials and methods: Using our musculoskeletal in silico modelling constrained against in vivo data from patients with instrumented knee implants allowed us to assess internal loads in femur and tibia. These internal forces were associated with the clinical outcome of fracture healing in a relevant cohort of 178 extra-articular femur and tibia fractures in patients using a retrospective approach. Results: Mean peak forces differed with femoral compression (1,330-1,936 N at mid-shaft) amounting to about half of tibial compression (2,299-5,224 N). Mean peak bending moments in the frontal plane were greater in the femur (71-130 Nm) than in the tibia (from 26 to 43 Nm), each increasing proximally. Bending in the sagittal plane showed smaller mean peak bending moments in the femur (-38 to 43 Nm) reaching substantially higher values in the tibia (-63 to -175 Nm) with a peak proximally. Peak torsional moments had opposite directions for the femur (-13 to -40 Nm) versus tibia (15-48 Nm) with an increase towards the proximal end in both. Femoral fractures showed significantly lower scores in the modified Radiological Union Scale for Tibia (mRUST) at last follow-up (p < 0.001) compared to tibial fractures. Specifically, compression (r = 0.304), sagittal bending (r = 0.259), and frontal bending (r = -0.318) showed strong associations (p < 0.001) to mRUST at last follow-up. This was not the case for age, body weight, or localisation alone. Discussion: This study showed that moments in femur and tibia tend to decrease towards their distal ends. Tibial load components were influenced by knee flexion angle, especially at push-off, while static frontal alignment played a smaller role. Our results indicate that femur and tibia are loaded differently and thus require adapted fracture fixation considering load components rather than just overall load level.

Reliability of the Modified Radiographic Union Score for Tibia Fractures (mRUST) for Femoral Shaft Fractures

OBJECTIVES

To evaluate the interobserver and intraobserver reliability of the modified Radiographic Union Score for Tibia Fractures (mRUST) and the effect of rater experience in evaluation of femoral fractures.

DESIGN

Retrospective cohort study.

SETTING

Single Level 1 trauma center.

PATIENTS/PARTICIPANTS

Patients 18-55 years of age with a femur shaft fracture.

INTERVENTION

Intramedullary nail fixation.

MAIN OUTCOME MEASUREMENT

Interobserver and intraobserver reliability using the intraclass correlation coefficient.

RESULTS

The overall interobserver reliability was 0.96. Among fellowship-trained evaluators, the interobserver reliability was 0.94, and it was 0.92 among trainees. The overall intraobserver reliability was 0.98. The intraobserver reliability was 0.97 among fellowship-trained evaluators and 0.96 for trainees.

CONCLUSIONS

These results show high interobserver and intraobserver reliability of mRUST in the evaluation of radiographic healing for femur shaft fractures treated with intramedullary nail. This high reliability was further demonstrated throughout different postoperative healing time frames. In addition, mRUST appears to be reliable when used both by trainees and experienced surgeons for the evaluation of femur shaft fractures.

LEVEL OF EVIDENCE

Diagnostic Level I. See Instructions for Authors for a complete description of levels of evidence.

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.

Clinical Assessments of Fracture Healing and Basic Science Correlates: Is There Room for Convergence?

PURPOSE OF REVIEW

The purpose of this review is to summarize the clinical and basic science methods used to assess fracture healing and propose a framework to improve the translational possibilities.

RECENT FINDINGS

Mainstays of fracture healing assessment include clinical examination, various imaging modalities, and assessment of function. Pre-clinical studies have yielded insight into biomechanical progression as well as the genetic, molecular, and cellular processes of fracture healing. Efforts are emerging to identify early markers to predict impaired healing and possibly early intervention to alter these processes. Despite of the differences in clinical and preclinical research, opportunities exist to unify and improve the translational efforts between these arenas to develop and optimize our ability to assess and predict fracture healing, thereby improving the clinical care of these patients.

Radiographic union score for tibia (RUST) scoring system in adult diaphyseal femoral fractures treated with intramedullary nailing: an assessment of interobserver and intraobserver reliability

OBJECTIVES

The Radiographic Union Score for Tibia (RUST) scoring system has been validated in multiple studies assessing the healing of tibial fractures. Our objective was to assess the interobserver and intraobserver reliability for the RUST in diaphyseal femoral fractures treated with intramedullary (IM) nailing.

PATIENTS AND METHODS

A total of 60 sets of anteroposterior (AP) and lateral radiographs of diaphyseal femoral fractures treated by reamed IM nailing were randomly selected from a prospectively collected database. The 60 sets of radiographs were then scored by three reviewers using the RUST system. Interobserver reliability was measured at initial scoring. The 60 sets of radiographs were scored again by the three reviewers to calculate the intraobserver reliability.

RESULTS

The RUST scores ranged from 4 to 12 with a mean score of 11.3 ± 1.3. The interobserver intraclass correlation coefficient (ICC) was 0.87 (95% CI, 0.81-0.92) and the intraobserver ICC was 0.91 (95% CI, 0.88-0.94), which indicated excellent agreement.

CONCLUSION

This study demonstrated that the RUST system can be used reliably in the assessment of healing in diaphyseal femur fractures treated by reamed intramedullary nailing, with excellent interobserver and intraobserver reliability.

Evaluation of a modified radiographic union scale for tibial fractures scoring system in staged bilateral tibial plateau leveling osteotomy procedures and comparison of first and second side radiographic bone healing

OBJECTIVE

To evaluate the inter- and intra-rater reliability of the tibial plateau leveling osteotomy (TPLO) modified radiographic union scale for tibial fractures (mRUST), a semiquantitative scoring system, as compared with the subjective evaluation of radiographic union for staged TPLOs.

STUDY DESIGN

Retrospective study.

ANIMALS

Forty-eight dogs, 96 stifles.

METHODS

Medical records were reviewed for dogs with bilateral cranial cruciate ligament injuries diagnosed at presentation that underwent staged bilateral TPLOs within 6 months and had both immediate and recheck postoperative radiographs. Radiographs were anonymized, reviewers were blinded, radiographic union was evaluated subjectively, and TPLO mRUST scores were assigned.

RESULTS

The subjective evaluation's intra-rater reliability was 0.72 (Kappa 95% CI 0.65-0.79) and inter-rater reliability was 0.33 (Kappa 95% CI 0.28-0.39). The TPLO mRUST scoring system intra-rater reliability was 0.73 (95% CI 0.68-0.78) and inter-rater reliability was 0.56 (95% CI 0.41-0.68). There was no difference in the degree of bone healing quantified by the TPLO mRUST scoring system (95% CI - 0.1-1.2, P = .09) or subjective evaluation (P = .48) between the first and second side TPLOs. The TPLO mRUST scores were positively correlated with subjective healing (r = 0.94, 95% CI 0.92-0.96, P < .0001, and for scores ≥10/12, 99%, 244/246) were subjectively assigned as radiographically healed.

CONCLUSION

The TPLO mRUST scoring system improved inter-rater reliability compared to subjective evaluation of radiographic union.

CLINICAL SIGNIFICANCE

The TPLO mRUST scoring system should be considered as a semiquantitative supplemental tool for evaluating radiographic union.

Validation of the modified radiographic union score for tibia fractures (mRUST) in murine femoral fractures

Bony union is a primary predictor of outcome after surgical fixation of long bone fractures. Murine models offer many advantages in assessing bony healing due to their low costs and small size. However, current fracture recovery investigations in mice frequently rely on animal sacrifice and costly analyses. The modified Radiographic Union Score for Tibia fractures (mRUST) scoring system is a validated metric for evaluating bony healing in humans utilizing plain radiographs, which are relatively inexpensive and do not require animal sacrifice. However, its use has not been well established in murine models. The aim of this study was to characterize the longitudinal course of mRUST and compare mRUST to other conventional murine fracture analyses. 158 mice underwent surgically created midshaft femur fractures. Mice were evaluated after fracture creation and at 7, 10, 14, 17, 21, 24, 28, 35, and 42 days post-injury. mRUST scoring of plain radiographs was performed by three orthopaedic surgeons in a randomized, blinded fashion. Interrater correlations were calculated. Micro-computed tomography (μCT) was analyzed for tissue mineral density (TMD), total callus volume (TV), bone volume (BV), trabecular thickness, trabecular number, and trabecular separation. Histomorphometry measures of total callus area, cartilage area, fibrous tissue area, and bone area were performed in a blinded fashion. Ultimate torque, stiffness, toughness, and twist to failure were calculated from torque-twist curves. A sigmoidal log-logistic curve fit was generated for mRUST scores over time which shows mRUST scores of 4 to 6 at 7 days post-injury that improve to plateaus of 14 to 16 by 24 days post-injury. mRUST interrater correlations at each timepoint ranged from 0.51 to 0.86, indicating substantial agreement. mRUST scores correlated well with biomechanical, histomorphometry, and μCT parameters, such as ultimate torque (r=0.46, p<0.0001), manual stiffness (r=0.51, p<0.0001), bone percentage based on histomorphometry (r=0.86, p<0.0001), cartilage percentage (r=-0.87, p<0.0001), tissue mineral density (r=0.83, p<0.0001), BV/TV based on μCT (r=0.65, p<0.0001), and trabecular thickness (r=0.78, p<0.0001), among others. These data demonstrate that mRUST is reliable, trends temporally, and correlates to standard measures of murine fracture healing. Compared to other measures, mRUST is more cost-effective and non-terminal. The mRUST log-logistic curve could be used to characterize differences in fracture healing trajectory between experimental groups, enabling high-throughput analysis.

Enhancement of Impaired MRSA-Infected Fracture Healing by Combinatorial Antibiotics and Modulation of Sustained Inflammation

Fracture healing is impaired in the setting of infection, which begets protracted inflammation. The most problematic causative agent of musculoskeletal infection is methicillin-resistant Staphylococcus aureus (MRSA). We hypothesized that modulation of excessive inflammation combined with cell-penetrating antibiotic treatments facilitates fracture healing in a murine MRSA-infected femoral fracture model. Sterile and MRSA-contaminated open transverse femoral osteotomies were induced in 10-week-old male C57BL/6 mice and fixed via intramedullary nailing. In the initial therapeutic cohort, empty, vancomycin (V), rifampin (R), vancomycin-rifampin (VR), or vancomycin-rifampin-trametinib (VRT) hydrogels were applied to the fracture site intraoperatively. Rifampin was included because of its ability to penetrate eukaryotic cells to target intracellular bacteria. Unbiased screening demonstrated ERK activation was upregulated in the setting of MRSA infection. As such, the FDA-approved mitogen-activated protein kinase kinase (MEK)1-pERK1/2 inhibitor trametinib was evaluated as an adjunctive therapeutic agent to selectively mitigate excessive inflammation after infected fracture. Two additional cohorts were created mimicking immediate and delayed postoperative antibiotic administration. Systemic vancomycin or VR was administered for 2 weeks, followed by 2 weeks of VRT hydrogel or oral trametinib therapy. Hematologic, histological, and cytokine analyses were performed using serum and tissue isolates obtained at distinct postoperative intervals. Radiography and micro-computed tomography (μCT) were employed to assess fracture healing. Pro-inflammatory cytokine levels remained elevated in MRSA-infected mice with antibiotic treatment alone, but increasingly normalized with trametinib therapy. Impaired callus formation and malunion were consistently observed in the MRSA-infected groups and was partially salvaged with systemic antibiotic treatment alone. Mice that received VR alongside adjuvant MEK1-pERK1/2 inhibition displayed the greatest restoration of bone and osseous union. A combinatorial approach involving adjuvant cell-penetrating antibiotic treatments alongside mitigation of excessive inflammation enhanced healing of infected fractures. © 2022 American Society for Bone and Mineral Research (ASBMR).

Cryogel Scaffold-Mediated Delivery of Adipose-Derived Stem Cells Promotes Healing in Murine Model of Atrophic Non-Union

Non-union is defined as the permanent failure of a bone to heal and occurs clinically in 5% of fractures. Atrophic non-unions, characterized by absent/minimal callus formation, are poorly understood and difficult to treat. We recently demonstrated a novel murine model of atrophic non-union in the 3.6Col1A1-tk (Col1-tk) mouse, wherein dosing with the nucleoside analog ganciclovir (GCV) was used to deplete proliferating osteoprogenitor cells, leading to a radiographic and biomechanical non-union after the mid-shaft femur fracture. Using this Col1-tk atrophic non-union model, we hypothesized that the scaffold-mediated lentiviral delivery of doxycycline-inducible BMP-2 transgenes would induce osteogenesis at the fracture site. Cryogel scaffolds were used as a vehicle for GFP+ and BMP-2+ cell delivery to the site of non-union. Cryogel scaffolds were biofabricated through the cross-linking of a chitosan-gelatin polymer solution at subzero temperatures, which results in a macroporous, spongy structure that may be advantageous for a bone regeneration application. Murine adipose-derived stem cells were seeded onto the cryogel scaffolds, where they underwent lentiviral transduction. Following the establishment of atrophic non-unions in the femurs of Col1-tk mice (4 weeks post-fracture), transduced, seeded scaffolds were surgically placed around the site of non-union, and the animals were given doxycycline water to induce BMP-2 production. Controls included GFP+ cells on the cryogel scaffolds, acellular scaffolds, and sham (no scaffold). Weekly radiographs were taken, and endpoint analysis included micro-CT and histological staining. After 2 weeks of implantation, the BMP-2+ scaffolds were infiltrated with cartilage and woven bone at the non-union site, while GFP+ scaffolds had woven bone formation. Later, timepoints of 8 weeks had woven bone and vessel formation within the BMP-2+ and GFP + scaffolds with cortical bridging of the original fracture site in both groups. Overall, the cell-seeded cryogels promoted osseous healing. However, while the addition of BMP-2 promoted the endochondral ossification, it may provide a slower route to healing. This proof-of-concept study demonstrates the potential for cellularized cryogel scaffolds to enhance the healing of non-unions.

Bone Union Assessment with Computed Tomography (CT) and Statistical Associations with Mechanical or Histological Testing: A Systematic Review of Animal Studies

Objective and accurate assessment of bone union after a fracture, arthrodesis, or osteotomy is relevant for scientific and clinical purposes. Bone union is most accurately imaged with computed tomography (CT), but no consensus exists about objective assessment of bone union from CT images. It is unclear which CT-generated parameters are most suitable for bone union assessment. The aim of this review of animal studies is to find which CT-generated parameters are associated most strongly with actual bone union. Scientific databases were systematically searched. Eligible studies were studies that (1) were animal studies, (2) created a fracture, (3) assessed bone union with CT, (4) performed mechanical or histological testing as measure of actual bone union, and (5) associated CT-generated outcomes to mechanical or histological testing results. Two authors selected eligible studies and performed risk of bias assessment with QUADAS-2 tool. From 2567 studies that were screened, thirteen studies were included. Most common CT parameters that were investigated were bone mineral density, bone volume, and total callus volume. Studies showed conflicting results concerning the associations of these parameters with actual bone union. CT-assessed torsional rigidity (assessed by three studies) and callus density (assessed by two studies) showed best results. The studies investigating these two parameters reported moderate to strong associations with actual bone union. CT-assessed torsional rigidity and callus density seem the most promising parameters to represent actual bone union after a fracture, arthrodesis, or osteotomy.Prospero trial registration number: CRD42020164733.

Internal Fixation Construct and Defect Size Affect Healing of a Translational Porcine Diaphyseal Tibial Segmental Bone Defect

BACKGROUND AND OBJECTIVE

Porcine translational models have become the gold-standard translational tool to study the effects of major injury and hemorrhagic shock because of their similarity to the human immunologic response to trauma. Segmental bone defects (SBDs) typically occur in warfighters with associated severe limb trauma. The purpose of this study was to develop a translational porcine diaphyseal SBD model in Yucatan minipigs (YMPs), which could be used in bone healing investigations that simulate injury-relevant conditions. We were specifically working toward developing a critical sized defect (CSD).

METHODS

We used an adaptive experimental design in which both 25.0 mm and 40.0 mm SBDs were created in the tibial mid-diaphysis in skeletally mature YMPs. Initially, eight YMPs were subjected to a 25.0 mm SBD and treated with intramedullary nailing (intramedullary nail [IMN] 25mm). Due to unanticipated wound problems, we subsequently treated four specimens with identical 25.0 mm defect with dual plating (open reduction with internal fixation [ORIF] 25mm). Finally, a third group of four YMPs with 40.0 mm defects were treated with dual plating (ORIF 40mm). Monthly radiographs were made until sacrifice. Modified Radiographic Union Score for Tibia fractures (mRUST) measurements were made by three trauma-trained orthopedic surgeons. CT scans of the tibias were used to verify the union results.

RESULTS

At 4 months post-surgery, mean mRUST scores were 11.7 (SD ± 1.8) in the ORIF 25mm YMPs vs. 8.5 (SD  ± 1.4) in the IMN 25mm YMPs (P < .0001). All four ORIF 25mm YMPs were clinically healed. In contrast, none of the IMN 25mm YMPs were clinically healed and seven of eight IMN 25mm YMPs developed delayed wound breakdown. All four of the ORIF 40mm YMPs had flail nonunions with complete hardware failure by 3 months after surgery and were sacrificed early. CT scanning confirmed that none of the IMN 25mm YMPs, none of the ORIF 40mm YMPs, and two of four ORIF 25mm YMPs were healed. A third ORIF 25mm specimen was nearly healed on CT scanning. Inter-rater and intra-rater reliability interclass coefficients using the mRUST scale were 0.81 and 0.80, respectively.

CONCLUSIONS

YMPs that had a 40 mm segment of bone removed from their tibia and were treated with dual plating did not heal and could be used to investigate interventions that accelerate bone healing. In contrast, a 25 mm SBD treated with dual plating demonstrated delayed but successful healing, indicating it can potentially be used to investigate bone healing adjuncts or conversely how concomitant injuries may impair bone healing. Pigs treated with IMN failed to heal and developed consistent delayed wound breakdown presumably secondary to chronic limb instability. The porcine YMP SBD model has the potential to be an effective translational tool to investigate bone healing under physiologically relevant injury conditions.

Bone Morphogenetic Protein-2 Rapidly Heals Two Distinct Critical Sized Segmental Diaphyseal Bone Defects in a Porcine Model

INTRODUCTION

Segmental bone defects (SBDs) are devastating injuries sustained by warfighters and are difficult to heal. Preclinical models that accurately simulate human conditions are necessary to investigate therapies to treat SBDs. We have developed two novel porcine SBD models that take advantage of similarities in bone healing and immunologic response to injury between pigs and humans. The purpose of this study was to investigate the efficacy of Bone Morphogenetic Protein-2 (BMP-2) to heal a critical sized defect (CSD) in two novel porcine SBD models.

MATERIALS AND METHODS

Two CSDs were performed in Yucatan Minipigs including a 25.0-mm SBD treated with intramedullary nailing (IMN) and a 40.0-mm SBD treated with dual plating (ORIF). In control animals, the defect was filled with a custom spacer and a bovine collagen sponge impregnated with saline (IMN25 Cont, n = 8; ORIF40 Cont, n = 4). In experimental animals, the SBD was filled with a custom spacer and a bovine collage sponge impregnated with human recombinant BMP-2 (IMN25 BMP, n = 8; ORIF40 BMP, n = 4). Healing was quantified using monthly modified Radiographic Union Score for Tibia Fractures (mRUST) scores, postmortem CT scanning, and torsion testing.

RESULTS

BMP-2 restored bone healing in all eight IMN25 BMP specimens and three of four ORIF40 BMP specimens. None of the IMN25 Cont or ORIF40 Cont specimens healed. mRUST scores at the time of sacrifice increased from 9.2 (±2.4) in IMN25 Cont to 15.1 (±1.0) in IMN25 BMP specimens (P < .0001). mRUST scores increased from 8.2 (±1.1) in ORIF40 Cont to 14.3 (±1.0) in ORIF40 BMP specimens (P < .01). CT scans confirmed all BMP-2 specimens had healed and none of the control specimens had healed in both IMN and ORIF groups. BMP-2 restored 114% and 93% of intact torsional stiffness in IMN25 BMP and ORIF40 BMP specimens.

CONCLUSIONS

We have developed two porcine CSD models, including fixation with IMN and with dual-plate fixation. Porcine models are particularly relevant for SBD research as the porcine immunologic response to injury closely mimics the human response. BMP-2 restored healing in both CSD models, and the effects were evident within the first month after injury. These findings support the use of both porcine CSD models to investigate new therapies to heal SBDs.

The orthopaedic surgeon's clinical and experimental experience affect methods used for the fracture healing assessment (FHA) - An International Survey

Detection of fracture healing (FH), which depends on assessment methods, is a crucial factor affecting treatment. The study aimed to examine orthopedic surgeons in terms of practical methods of fracture healing (FHA) assessment (physical, imaging, measurement, and laboratory) and to check whether surgeons participating in clinical and laboratory experiments or only clinical practitioners prefer different FHA methods. An International Survey on Fracture Healing Assessment Methods was developed and distributed through the Web-based survey portal. Ninety-three orthopedic surgeons, on average age 41.46 years, from 24 countries participated in the study. Thirty-one respondents (33.3%) reported dealing with fractures both in the clinic and in experimental studies, six (6.5%) reported dealing with fractures only in laboratory research work, and fifty-six (60.2%) indicated that they dealt with fractures only clinically. The survey's internal consistency was significantly high (Cronbach's alpha coefficients ranged from 0.84 to 0.96). The majority of respondents (80.83%) use specific clinical criteria to define a fracture union. The FHA was mainly based on the physical examination and plain radiograms. Laboratory findings, patient-oriented outcomes scores, and quantitative methods are rarely used. Orthopaedic surgeons dealing with fractures both in the clinic and in laboratory fracture research studies are more likely to use more quantitative FHA methods. Future research is needed to improve the international standard of the FHA methods for use in research, clinical trials, and clinical practice. Using a quantitative, reliable, and standardized approach, including online support, can be valuable for increasing compliance in the orthopedic surgeon population, effectively improving the adherence of fracture healing assessment in clinical conditions, and improving early detection of fracture healing disorders, improving fracture efficiency treatment.

Squat and smile assessment in predicting healing of lower limb fractures fixed with a SIGN nail

BACKGROUND

Irrespective of the treatment method, union is the ultimate goal of any fracture treatment. However, nowadays, rather than the physician-based clinico-radiological methods, the patient-reported outcome measurements assessing their quality of life and function are gaining much popularity. This is specifically true in the part of the world where the patient needs almost complete degree of hip/knee flexion - for social, cultural, religious or occupational reason(s). The ability to squat can assess the mobility and stability of joints and thus the quality of squatting is a proxy reflection of the functional outcome after fixation of lower limb fracture. Thus, we studied to determine the inter-observer and intra-observer reliability of Radiographic Union Score for Tibia (RUST) and Squat and Smile (S & S) test in clinical photograph. We further calculated the sensitivity and specificity of S & S test in predicting healing of lower limb fracture fixed by intramedullary interlocking nail considering RUST as the gold standard.

METHODS

This was a retrospective study of prospectively collected data of solid Surgical Implant Generation Network (SIGN) intramedullary interlocking nailing from a single, university-based, high volume tertiary center where 56 consecutive adults with either tibial or femoral shaft fractures fixed with a SIGN nail within one year and not requiring any surgery till minimum of eighteen-month follow-up were included. Cases without either Anterior-Posterior (AP) view and/or Lateral (Lat.) view follow-up x-ray(s) or proper S & S clinical photograph (at least 1.5-year post fixation) were excluded. The x-rays (RUST criteria) and clinical photograph (S & S grading) were scored by two independent and blinded observers each and repeated after 1 month.

RESULTS

The overall intra-observer reliability was from 0.773 to 0.825 and inter-observer reliability from 0.635 to 0.757 for RUST scoring which was from 0.687 to 0.785 and from 0.301 to 0.650 respectively for S & S scoring. The sensitivity and specificity of S & S in predicting fracture healing were up to 82.22% and 63.64% respectively.

CONCLUSION

The S & S test is reliable to predict the healing of lower limb fracture fixed with an intramedullary nail. The test is more useful to determine healed fractures than to determine non-healed ones. (sensitivity being higher than specificity).

Virtual mechanical tests out-perform morphometric measures for assessment of mechanical stability of fracture healing in vivo

Finite element analysis with models derived from computed tomography (CT) scans is potentially powerful as a translational research tool because it can achieve what animal studies and cadaver biomechanics cannot-low-risk, noninvasive, objective assessment of outcomes in living humans who have actually experienced the injury, or treatment being studied. The purpose of this study was to assess the validity of CT-based virtual mechanical testing with respect to physical biomechanical tests in a large animal model. Three different tibial osteotomy models were performed on 44 sheep. Data from 33 operated limbs and 20 intact limbs was retrospectively analyzed. Radiographic union scoring was performed on the operated limbs and physical torsional tests were performed on all limbs. Morphometric measures and finite element models were developed from CT scans and virtual torsional tests were performed to assess healing with four material assignment techniques. In correlation analysis, morphometric measures and radiographic scores were unreliable predictors of biomechanical rigidity, while the virtual torsion test results were strongly and significantly correlated with measured biomechanical test data, with high absolute agreement. Overall, the results validated the use of virtual mechanical testing as a reliable in vivo assessment of structural bone healing. This method is readily translatable to clinical evaluation for noninvasive assessment of the healing progress of fractures with minimal risk. Clinical significance: virtual mechanical testing can be used to reliably and noninvasively assess the rigidity of a healing fracture using clinical-resolution CT scans and that this measure is superior to morphometric and radiographic measures.

Semi-quantitative CT scoring of nailed shaft fractures during normal healing and in non-unions: comparison with radiographic scoring

PURPOSE

To compare tomographic (TUS) with radiographic (RUS) union scores in nailed shaft fractures during normal healing and in non-unions.

METHODS

Two radiologists blinded to fracture age separately determined RUS and TUS in nailed femoral or tibial shaft fractures by analyzing the radiographic and CT examinations obtained in 47 patients during normal healing (early fracture group; 24 study participants, 17 men,19 tibias, mean fracture-CT delay 109 ± 57 days [42-204 days]) and in surgically proven non-united fractures (late fracture group, 23 patients, 14 men, 12 tibias, mean fracture-CT delay 565 ± 519 days[180-1983 days]). In both study groups, we determined the inter- and intra-observer agreement of RUS and TUS and compared TUS with RUS.

RESULTS

Intra- and inter-observer agreement of RUS and TUS was very good in the early fracture group and good in the late fracture group for both readers. TUS correlated with RUS substantially in the early fracture group and only weakly in the late fracture group. TUS was statistically significantly lower than RUS in study participants with RUS ≥ 8 or 9 for R2 only and ≥ 10 for both readers in the early fracture group and in patients with RUS ≥ 8, 9 or 10 in the late fracture group for both readers.

CONCLUSION

RUS and TUS of nailed shaft fractures during normal healing or in non-unions are both feasible and reproducible. They yield similar values in fractures with no or limited callus. TUS yields lower values than RUS in fractures with callus.

Locally delivered adjuvant biofilm-penetrating antibiotics rescue impaired endochondral fracture healing caused by MRSA infection

Infection is a devastating complication following an open fracture. We investigated whether local rifampin-loaded hydrogel can combat infection and improve healing in a murine model of methicillin-resistant Staphylococcus aureus (MRSA) osteomyelitis. A transverse fracture was made at the tibia midshaft of C57BL/6J mice aged 10-12 weeks and stabilized with an intramedullary pin. A total of 1 × 106 colony-forming units (CFU) of MRSA was inoculated. A collagen-based hydrogel containing low-dose (60 μg) and high-dose (300 μg) rifampin was applied before closure. Postoperative treatment response was assessed through bacterial CFU counts from tissue and hardware, tibial radiographs and microcomputed tomography (μCT), immunohistochemistry, and histological analyses. All untreated MRSA-infected fractures progressed to nonunion by 28 days with profuse MRSA colonization. Infected fractures demonstrated decreased soft callus formation on safranin O stain compared to controls. Areas of dense interleukin-1β stain were associated with poor callus formation. High-dose rifampin hydrogels reduced the average MRSA load in tissue (p < 0.0001) and implants (p = 0.041). Low-dose rifampin hydrogels reduced tissue bacterial load by 50% (p = 0.021). Among sterile models, 88% achieved union compared to 0% of those infected. Mean radiographic union scale in tibia scores improved from 6 to 8.7 with high-dose rifampin hydrogel (p = 0.024) and to 10 with combination local/systemic rifampin therapy (p < 0.0001). μCT demonstrated reactive bone formation in MRSA infection. Histology demonstrated restored fracture healing with bacterial elimination. Rifampin-loaded hydrogels suppressed osteomyelitis, prevented implant colonization, and improved healing. Systemic rifampin was more effective at eliminating infection and improving fracture healing. Further investigation into rifampin-loaded hydrogels is required to correlate these findings with clinical efficacy.

Overview of Skeletal Repair (Fracture Healing and Its Assessment)

The study of postnatal skeletal repair is of immense clinical interest. Optimal repair of skeletal tissue is necessary in all varieties of elective and reparative orthopedic surgical treatments. However, the repair of fractures is unique in this context in that fractures are one of the most common traumas that humans experience and are the end-point manifestation of osteoporosis, the most common chronic disease of aging. In the first part of this introduction the basic biology of fracture healing is presented. The second part discusses the primary methodological approaches that are used to examine repair of skeletal hard tissue and specific considerations for choosing among and implementing these approaches.

Smoking Alters Inflammation and Skeletal Stem and Progenitor Cell Activity During Fracture Healing in Different Murine Strains

Smokers are at a higher risk of delayed union or nonunion after fracture repair. Few specific interventions are available for prevention because the molecular mechanisms that result in these negative sequelae are poorly understood. Murine models that mimic fracture healing in smokers are crucial in further understanding the local cellular and molecular alterations during fracture healing caused by smoking. We exposed three murine strains, C57BL/6J, 129X1/SvJ, and BALB/cJ, to cigarette smoke for 3 months before the induction of a midshaft transverse femoral osteotomy. We evaluated fracture healing 4 weeks after the osteotomy using radiography, micro-computed tomography (μCT), and biomechanical testing. Radiographic analysis demonstrated a significant decrease in the fracture healing capacity of smoking 129X1/SvJ mice. μCT results showed delayed remodeling of fracture calluses in all three strains after cigarette smoke exposure. Biomechanical testing indicated the most significant impairment in the functional properties of 129X1/SvJ in comparison with C57BL/6J and BALB/cJ mice after cigarette smoke exposure. Thus, the 129X1/SvJ strain is most suitable in simulating smoking-induced impaired fracture healing. Furthermore, in smoking 129X1/SvJ murine models, we investigated the molecular and cellular alterations in fracture healing caused by cigarette smoking using histology, flow cytometry, and multiplex cytokine/chemokine analysis. Histological analysis showed impaired chondrogenesis in cigarette smoking. In addition, the important reparative cell populations, including skeletal stem cells and their downstream progenitors, demonstrated decreased expansion after injury as a result of cigarette smoking. Moreover, significantly increased pro-inflammatory mediators and the recruitment of immune cells in fracture hematomas were demonstrated in smoking mice. Collectively, our findings demonstrate the significant cellular and molecular alterations during fracture healing impaired by smoking, including disrupted chondrogenesis, aberrant skeletal stem and progenitor cell activity, and a pronounced initial inflammatory response. © 2020 American Society for Bone and Mineral Research (ASBMR).

Reliability of RUST and Modified RUST Scores for the Evaluation of Union in Humeral Shaft Fractures Treated with Different Techniques

BACKGROUND

The study aimed to evaluate the agreement between the radiographic union scale (RUST) and modified RUST (mRUST) in humeral shaft fractures treated with different techniques, and the effect of surgeons' experience and thresholds for determining bone union.

MATERIALS AND METHODS

A total of 20 orthopedic surgeons reviewed and scored radiographs of 30 patients with humeral shaft fractures treated by external fixation, intramedullary nailing, and plating using the RUST and mRUST on the 0 day, 6 weeks, 12 weeks and 24 weeks follow-up radiographs. Bone healing, interrater agreement between RUST and mRUST scores, and the threshold for radiographic union were evaluated.

RESULTS

The intraclass correlation coefficient (ICC) was slightly higher for the mRUST score than the RUST score (0.71 versus [vs.] 0.67). There was substantial agreement between the mRUST and RUST scores for external fixation (0.75 and 0.69, respectively) and intramedullary nailing (0.79 and 0.71); there was moderate agreement between them for plating (0.59 and 0.55). Surgeons with varying experience had a similar agreement for both scores and scores for each humeral cortex. The external fixation and intramedullary nailing group had higher RUST and mRUST scores than the plating group. The ICC for union was substantial (0.64; external fixation: 0.68, intramedullary nailing: 0.64, and plating: 0.61). More than 90% of the reviewers recorded scores of 10/12 for RUST and 13/16 for mRUST at the time of union.

CONCLUSIONS

RUST and mRUST scores can be used reliably for the evaluation of bony union in humeral fractures treated with an external fixator and intramedullary nailing. In cases of humeral plating, a more sensitive tool for evaluation of fracture union is needed.

Epidemiology, Clinical Assessments, and Current Treatments of Nonunions

PURPOSE OF REVIEW

The failure of bony union following a fracture, termed a fracture nonunion, has severe patient morbidity and economic consequences. This review describes current consensuses and future directions of investigation for determining why, detecting when, and effective treatment if this complication occurs.

RECENT FINDINGS

Current nonunion investigation is emphasizing an expanded understanding of the biology of healing. This has led to assessments of the immune environment, multiple cytokines and morphogenetic factors, and the role of skeletogenic stem cells in the development of nonunion. Detecting biological markers and other objective diagnostic criteria is also a current objective of nonunion research. Treatment approaches in the near future will likely be dominated by the development of specific adjunct therapies to the nonunion surgical management, which will be informed by an expanded mechanistic understanding of nonunion biology. Current consensus among orthopedists is that improved diagnosis and treatment of nonunion hinges first on discoveries at the bench side with later translation to the clinic.

Imaging Modalities to Assess Fracture Healing

PURPOSE OF REVIEW

This review discusses imaging modalities for fracture repair assessment, with an emphasis on pragmatic clinical and translational use, best practices for implementation, and challenges and opportunities for continuing research.

RECENT FINDINGS

Semiquantitative radiographic union scoring remains the clinical gold standard, but has questionable reliability as a surrogate indicator of structural bone healing, particularly in early-stage, complex, or compromised healing scenarios. Alternatively, computed tomography (CT) scanning enables quantitative assessment of callus morphometry and mechanics through the use of patient-specific finite-element models. Dual-energy X-ray absorptiometry (DXA) scanning and radiostereometric analysis (RSA) are also quantitative, but technically challenging. Nonionizing magnetic resonance (MR) and ultrasound imaging are of high interest, but require development to enable quantification of 3D mineralized structures. Emerging image-based methods for quantitative assessment of bone healing may transform clinical research design by displacing binary outcomes classification (union/nonunion) and ultimately enhance clinical care by enabling early nonunion detection.

Radiographic evaluations: Which are most effective to follow fracture healing?

The assessment of fracture healing is an imperative and fundamental clinical aspect within orthopaedics. Despite that, there have historically been non-reliable methods utilized to assess for fracture union and nonunion. In recent years, a number of radiographic assessment tools such as the Radiographic Union Score for Tibial fractures (RUST) and Radiographic Union Score for Hip fracture (RUSH) have been developed in order to improve the reliability of fracture assessment for union. These scores have not only increased the reliability of assessments but have also provided thresholds to aid in predicting nonunion as well as union. The nonunion risk determination (NURD) Score was also created to prognosticate these clinical presentations. With the large burdens of cost, lower quality of life and morbidity associated with fracture nonunion, these evaluation methods have provided orthopaedic surgeons with an improved ability to predict nonunion and assist in the management of patients. This review outlines the development, reliability testing as well as biomechanical validity testing associated with these scoring systems.

The top three unanswered questions in the management of open fractures

Despite improvements in treatment strategies and emphasis on preventative measures, the management of open fractures continues to be a challenging endeavor for orthopaedic surgeons. Deep infections, delayed healing, and nonunion continue to be problematic complications associated with these devastating injuries. There remain many unanswered clinical questions regarding the management of these injuries and how the various aspects of care can be further optimized. There continues to be a paucity of evidence regarding how infection can best be treated and prevented, how to reliability predict bone healing/nonunion, and how bone healing can be best augmented in the setting of open fractures and their potential nonunions. This review aims to assess the current literature on these top unanswered questions and discuss the gaps in evidence that may be filled with future studies.