Current Options for Determining Fracture Union

A novel quantitative and reference-free ultrasound analysis to discriminate different concentrations of bone mineral content

Bone fracture is a continuous process, during which bone mineral matrix evolves leading to an increase in hydroxyapatite and calcium carbonate content. Currently, no gold standard methods are available for a quantitative assessment of bone fracture healing. Moreover, the available tools do not provide information on bone composition. Whereby, there is a need for objective and non-invasive methods to monitor the evolution of bone mineral content. In general, ultrasound can guarantee a quantitative characterization of tissues. However, previous studies required measurements on reference samples. In this paper we propose a novel and reference-free parameter, based on the entropy of the phase signal calculated from the backscattered data in combination with amplitude information, to also consider absorption and scattering phenomena. The proposed metric was effective in discriminating different hydroxyapatite (from 10 to 50% w/v) and calcium carbonate (from 2 to 6% w/v) concentrations in bone-mimicking phantoms without the need for reference measurements, paving the way to their translational use for the diagnosis of tissue healing. To the best of our knowledge this is the first time that the phase entropy of the backscattered ultrasound signals is exploited for monitoring changes in the mineral content of bone-like materials.

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).

Time to debridement in open high-grade lower limb fractures and its effect on union and infections: A prospective study in a tropical setting

PURPOSE

To prospectively evaluate whether time to debridement has any correlation with union, infection, and quality of life in high-grade lower limb fractures in a tropical setting.

METHODS

A prospective cohort study was conducted at a tertiary care center in South India. Two hundred fifty-four adult skeletally mature patients with 301 grade 3 fractures involving the femur, tibia, or fibula were recruited. The cohort was empirically divided into two groups (early and late) based on the time to debridement (less than or more than 12 h from injury).

OUTCOME

The primary outcome was nonunion. Secondary outcomes were deep infection rates and patients' quality of life. Short form-36 (SF-36) and short musculoskeletal functional assessment (SMFA) questionnaires were also used. Patients were followed up for 9 months.

RESULTS

The follow-up rate was 93%. The late group had a significantly higher risk of nonunion (odds ratio(OR): 6.5, 95% confidence interval (CI): 2.82-14.95) and infections (OR: 6.05, 95% CI: 2.85-12.82). There was a 4% increase in the infection risk for each hour of delay for the initial 50 h (p < 0.0001). SF-36 and SMFA scores were superior in the early group (p < 0.0001).

CONCLUSION

The study contradicts findings reported in the literature from the West. Our study was in agreement with our hypothesis and proved that debridement within 12 h resulted in significantly lower rates of nonunion and infections and an overall improved quality of life in high-grade open lower limb fractures in a developing country.

LEVEL OF EVIDENCE

Level II.

TRIAL REGISTRATION

German Clinical Trials Register DRKS00015186.

Growth Factors, Carrier Materials, and Bone Repair

This chapter provides an overview of the growth factors active in bone regeneration and healing. Both normal and impaired bone healing are discussed, with a focus on the spatiotemporal activity of the various growth factors known to be involved in the healing response. The review highlights the activities of most important growth factors impacting bone regeneration, with a particular emphasis on those being pursued for clinical translation or which have already been marketed as components of bone regenerative materials. Current approaches the use of bone grafts in clinical settings of bone repair (including bone grafts) are summarized, and carrier systems (scaffolds) for bone tissue engineering via localized growth factor delivery are reviewed. The chapter concludes with a consideration of how bone repair might be improved in the future.

Reliability of Radiographic Union Scoring in Humeral Shaft Fractures

OBJECTIVES

To establish the reliability of 2 radiographic union scoring systems for nonoperative humeral shaft fractures.

DESIGN

Retrospective medical record review. Patients identified had humeral shaft fractures and radiographs at various follow-up time points, which were graded according to the both the standard (RUST) and modified radiographic union scoring systems (mRUST).

SETTING

A single North American Level-1 Trauma center in Connecticut, including emergency department and clinic follow-up visits.

PATIENTS/PARTICIPANTS

Forty-five adult patients (162 image sets) met the following inclusion criteria: diaphyseal humerus fracture, initial nonoperative management, and greater than 2 weeks of follow-up with imaging.

INTERVENTION

All 162 image sets of anterior-posterior and lateral radiographs were scored and divided into 4 tiers based on increasing score. Anterior-posterior and lateral image sets were randomly selected from each tier for a total of 50 that were then scored by 7 different reviewers using both the RUST and mRUST systems.

MAIN OUTCOME MEASURES

The intraclass correlation coefficients for the cortical and system scores for the RUST and mRUST systems.

RESULTS

Interobserver reliability was 0.795 for the RUST system and 0.801 for mRUST. Intraobserver reliability was 0.909 for RUST and 0.949 for mRUST. For mRUST, 92% of values were within ± 1 point from each other.

CONCLUSIONS

The RUST and mRUST systems can be applied to humeral shaft fractures with excellent reliability. They have the potential to assist in the diagnosis of humeral shaft union by providing an objective and standardized method to assess healing of bone over time.

Effects of Stellate Ganglion Block on Healing of Fractures Induced in Rats

Objective

Sympathetic blocks are used as an adjunct for pain management in the treatment of orthopedic and traumatic conditions. Stellate ganglion (ganglion stellatum) provides sympathetic innervation of the head, neck and cervicothoracic regions, and upper extremities. No study was found in the literature investigating the effects of stellate ganglion block performed in the upper extremity, on blood supply to bone, density, vascularization, and bone metabolism. Therefore, the objective of this study was to investigate the effects of stellate ganglion block on healing of closed forearm fractures that were induced in rats. Material and Methods. A total of 42 Wistar albino rats weighing between 398 and 510 g were used in this study. The rats were randomly divided into 2 groups with one group treated with stellate ganglion and the other included as the control group. In each 2 groups, a closed forearm fracture was created, confirmed with X-ray, and then stabilized by splint application. The forearm bones were examined with X-ray views on the same day and were then decalcified.

Results

When histological findings of the fracture region were examined, predominantly cartilage and less woven bone were found in 7 rats, equally distributed cartilage and immature bone in 14 rats, and predominantly imitation bone and less cartilage formation in 21 rats. In the control group, the agreement between the 1st and 2nd orthopedists for the radiological evaluation of bone formation was moderate.

Conclusion

The group administered stellate ganglion block showed a more significant fracture healing.

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.

The Life of a Fracture: Biologic Progression, Healing Gone Awry, and Evaluation of Union

New knowledge about the molecular biology of fracture-healing provides opportunities for intervention and reduction of risk for specific phases that are affected by disease and medications. Modifiable and nonmodifiable risk factors can prolong healing, and the informed clinician should optimize each patient to provide the best chance for union. Techniques to monitor progression of fracture-healing have not changed substantially over time; new objective modalities are needed.

Deficiency of PDK1 in osteoclasts delays fracture healing and repair

Bone fractures are common traumatic injuries of the musculoskeletal system. However, delayed union and non‑union fractures are a major clinical problem that present significant socioeconomic burden to patients and the public health sector. The bone‑resorbing osteoclasts and bone‑forming osteoblasts serve important roles in the fracture repair/healing process. Osteoclast deficiency or decreased osteoblast activity negatively impacts fracture healing. We previously demonstrated that the specific deletion of the serine/threonine kinase 3‑phosphoinositide‑dependent protein kinase 1 (PDK1) in osteoclasts leads to abrogated osteoclast formation and bone resorption in response to receptor activator of nuclear factor‑κB in vitro and protected mice against ovariectomized‑induced bone loss and lipopolysaccharide‑induced osteolysis in vivo. Given the importance of osteoclasts in fracture repair, we hypothesized that the specific loss of PDK1 in osteoclasts will alter the fracture healing process. Mice of tibial fracture were constructed, and tibial specimens were sampled at 7‑, 14‑, 21‑ and 28‑days post‑fracture to observe the effect of PDK1 gene regulated osteoclasts on fracture healing process by X‑ray radiography, microcomputed tomography scanning, histomorphological staining and biomechanical testing. The present study revealed, using the tibial fracture model, that the specific deletion of the PDK1 gene in osteoclasts impeded the fracture healing process by delaying the resorption of the cartilaginous callus and subsequent remodeling of immature woven bone to structurally and mechanically ensure lamellar bone is stronger. No effect on osteoblast bone formation and osteogenesis was observed, thus indicating that delayed fracture healing is primarily due to defective osteoclast activity. These results provide important clinical implications for the use of anti‑resorptive agents, such as bisphosphonates, for the treatment of osteolytic conditions. Such anti‑resorptive therapies may detrimentally delay fracture healing and repair.

The Effect of Postoperative Nonsteroidal Anti-inflammatory Drugs on Nonunion Rates in Long Bone Fractures

The association of nonsteroidal anti-inflammatory drugs (NSAIDs) with non-union in long bone fractures has been controversial. The purpose of this study was to evaluate whether NSAID exposure results in increased risk of non-union in operatively treated long bone fractures. The authors used International Classification of Diseases and Current Procedural Terminology codes to identify patients under a single-payer private insurance with operatively treated humeral shaft, tibial shaft, and subtrochanteric femur fractures from a large database. Patients were divided into cohorts based on NSAID use in the immediate postoperative period, and nonunion rates were compared. A cost analysis and a multivariate analysis were performed. Between 2007 and 2016, a total of 5310 tibial shaft, 3947 humeral shaft, and 8432 subtrochanteric femur fractures underwent operative fixation. Patients used NSAIDs in the first 90 days postoperatively in 900 tibial shaft, 694 humeral shaft, and 967 subtrochanteric femur fractures. In these patients, nonunion rates were 18.8%, 17.4%, and 10.4%, respectively. When no NSAIDs were used, the rates were 11.4%, 10.1%, and 4.6% for each fracture type, respectively (P<.05). Among patients taking NSAIDs, subtrochanteric femur fractures had a 2.4 times higher risk of nonunion and humeral shaft and tibial shaft fractures both had a 1.7 times higher risk of nonunion (P<.05). Multivariate analysis showed NSAID use to be an independent risk factor in all 3 types. Cost analysis showed a great increase in economic burden (P<.05). This study indicated that NSAID exposure was associated with fracture nonunion. [Orthopedics. 2020;43(4):221-227.].

NSM00158 Specifically Disrupts the CtBP2-p300 Interaction to Reverse CtBP2-Mediated Transrepression and Prevent the Occurrence of Nonunion

Carboxyl-terminal binding proteins (CtBPs) are transcription regulators that control gene expression in multiple cellular processes. Our recent findings indicated that overexpression of CtBP2 caused the repression of multiple bone development and differentiation genes, resulting in atrophic nonunion. Therefore, disrupting the CtBP2-associated transcriptional complex with small molecules may be an effective strategy to prevent nonunion. In the present study, we developed an in vitro screening system in yeast cells to identify small molecules capable of disrupting the CtBP2-p300 interaction. Herein, we focus our studies on revealing the in vitro and in vivo effects of a small molecule NSM00158, which showed the strongest inhibition of the CtBP2-p300 interaction in vitro. Our results indicated that NSM00158 could specifically disrupt CtBP2 function and cause the disassociation of the CtBP2-p300-Runx2 complex. The impairment of this complex led to failed binding of Runx2 to its downstream targets, causing their upregulation. Using a mouse fracture model, we evaluated the in vivo effect of NSM00158 on preventing nonunion. Consistent with the in vitro results, the NSM00158 treatment resulted in the upregulation of Runx2 downstream targets. Importantly, we found that the administration of NSM00158 could prevent the occurrence of nonunion. Our results suggest that NSM00158 represents a new potential compound to prevent the occurrence of nonunion by disrupting CtBP2 function and impairing the assembly of the CtBP2-p300-Runx2 transcriptional complex.

Surgical Fixation of Subtrochanteric Fracture in Patient with Cancellous Screw Fixation for Neck of Femur Fracture: Surgical Decision-Making and Outcome

Introduction

Cannulated screw fixation is a common technique employed for the closed reduction and fixation of minimally or non-displaced neck of femur (NOF) fractures. A rare but potentially devastating complication is a peri-implant subtrochanteric fracture. Given the possibility of dealing with two potentially unstable fractures in close proximity from an incomplete union of the femoral neck, surgical fixation must be carefully planned with the option of retaining the existing cancellous screws to maintain femoral neck stability. The authors describe a case of subtrochanteric fracture in a patient with an existing NOF fracture which was previously fixed with cancellous screw fixation and have provided our approach to such patients.

Case Report

The patient is a 73-year-old Chinese male with a previous cancellous screw fixation for an undisplaced NOF fracture 10 months before sustaining another fall resulting in a subtrochanteric fracture. Radiographs and computed tomography imaging revealed a peri-implant subtrochanteric fracture with fracture line originating distal to the inferior screw at the level of the lesser trochanter.The patient subsequently underwent a Trochanteric Fixation Nail-Advanced Proximal Femoral Nailing System (TFNA, Depuy Synthes) fixation of peri-implant subtrochanteric fracture. Two previous cancellous screws (superior-posterior and inferior-central) were first removed to allow the passage of the TFNA nail which just skirted the remaining superior-anterior screw.Postoperatively, the patient was allowed full weight-bearing with the patient managing to ambulate with a roller frame support on the immediate 1stpost-operative day. The subsequent progress was uneventful and at the final follow-up 6-month postoperatively, X-ray showed complete bony union and the patient is pain free and walking independently.

Conclusion

Peri-implant subtrochanteric fractures following NOF fractures treated with cancellous screws are surgically challenging. A robust system of evaluating such fractures and decision-making aids perioperative planning. An intimate understanding of implant geometries and basic science principles can significantly help in difficult cases and may reduce the likelihood of intraoperative difficulties and complications. Further large-scale studies are required to evaluate the validity of the approach we have proposed.

Characterization of a pluripotent stem cell-derived matrix with powerful osteoregenerative capabilities

Approximately 10% of fractures will not heal without intervention. Current treatments can be marginally effective, costly, and some have adverse effects. A safe and manufacturable mimic of anabolic bone is the primary goal of bone engineering, but achieving this is challenging. Mesenchymal stem cells (MSCs), are excellent candidates for engineering bone, but lack reproducibility due to donor source and culture methodology. The need for a bioactive attachment substrate also hinders progress. Herein, we describe a highly osteogenic MSC line generated from induced pluripotent stem cells that generates high yields of an osteogenic cell-matrix (ihOCM) in vitro. In mice, the intrinsic osteogenic activity of ihOCM surpasses bone morphogenic protein 2 (BMP2) driving healing of calvarial defects in 4 weeks by a mechanism mediated in part by collagen VI and XII. We propose that ihOCM may represent an effective replacement for autograft and BMP products used commonly in bone tissue engineering.

Production of a safe and manufacturable material to mimic anabolic bone for tissue engineering has been hard to achieve to date. Here the authors use a mesenchymal stem cell line generated from induced pluripotent stem cells to produce osteogenic cell-matrix, displaying significant healing properties in mice.

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.

Determining the optimal osteotomy distance with the fibula free flap in mandibular reconstruction

OBJECTIVE

Fibula free tissue transfer is a common and reliable method for mandibular reconstruction. Functional outcomes from this procedure are dependent on the successful union of the osseous segments postoperatively. This study was conducted to define the maximum gap-size criteria for osseous union to occur at osteotomy sites in fibula free flap reconstruction of the mandible.

STUDY DESIGN

Retrospective chart review.

SETTING

Tertiary care academic center.

SUBJECTS AND METHODS

A retrospective chart review of computed tomography and medical records was conducted on patients who underwent fibula free flap surgery and had imaging of the mandible at <3 months and >6 months after surgery. Distances between osteotomies were measured and evaluated for interval healing. Secondary data included subject age, sex, smoking status, diabetes, number of osteotomies, complications, and adjuvant therapy.

RESULTS

Thirty-eight osteotomy sites were analyzed from thirteen subjects and a total of 190 measurements were made. The mean gap size at the first scan that demonstrated union by the second scan interval was 1.31 mm and mean gap size demonstrating non-union was 2.55 mm (p < 0.01). Complication rate, number of osetotomies, adjuvant therapy, or medical co-morbidities did not significantly affect rates of union.

CONCLUSIONS

In this study, osseous union was achieved with a mean osteotomy gap size of 1.31 mm. The data suggests that distances between ossesous segments >2 .55mm have a higher risk of non-union. We believe the information from this study will help augment current and future techniques in the field of mandible reconstruction.

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.

Cambridge experience in spontaneous bone regeneration after traumatic segmental bone defect: a case series and review of literature

High-energy traumatic long bone defects are some of the most challenging to reconstruct. Although cases of spontaneous bone regeneration in these defects have been reported, we are aware of no management guidelines or recommendations for when spontaneous bone regeneration should be considered a viable management option. We aim to identify how certain patient characteristics and surgical factors may help predict spontaneous bone regeneration. A total of 26 cases with traumatic segmental defects were treated at our institution, with eight cases (30.8%) undergoing spontaneous regeneration. We discuss four in detail. Six (75%) reported a degree of periosteal preservation, four (50%) were associated with traumatic brain injury and none were complicated by infection. The average time to spontaneous bone regeneration was 2.06 months. According to our cases, patients with favourable characteristics may benefit from delaying surgical treatment by 6 weeks to monitor for any signs of spontaneous bone formation.

Validation of a long bone fracture non-union healing score after treatment with mesenchymal stromal cells combined to biomaterials

The available scores to clinically evaluate fracture consolidation encounter difficulties to interpret progression towards consolidation in long-bone non-union, particularly when incorporating biomaterials in the surgical treatment. The aims of this study were to validate the REBORNE bone healing scale in tibia, humerus and femur non-unions treated by a combination of mesenchymal stromal cells (MSCs) and biomaterials, through the interclass correlation (ICC) among raters, and to define reliability and concordance in anteroposterior and lateral radiographs, compared to computed tomography (CT).

METHODS

Twenty-six cases from the EudraCT 2011-005441-13 clinical trial underwent bone healing evaluation, if at least 3 out of 4 cortical views clearly identified. Three senior orthopaedic surgeons evaluated radiographs and CTs at 3 and 6 months FU. All cases included preoperative imaging and radiographs at 12 months. The 4-stage scale score was obtained from each cortical view in orthogonal radiographs or CTs. A score of 0.6875 (11/16) was set as a threshold for bone healing. Statistically, ICC evaluated agreement among raters. Cronbach's alpha coefficient tested reliability. Lin's concordance correlation coefficients (CCC) were estimated between mean CT scores and mean radiographic scores. Bland and Altman graphs provided the limits of agreement between both imaging techniques. Sensitivity and specificity were assessed in radiographs (against CT), and the Area Under the Receiver Operating Characteristics (ROC) Curve was estimated. The probability to predict bone consolidation with REBORNE scores obtained from radiographs was modelled.

RESULTS

An ICC of 0.88 and 0.91 (CT and radiographs) confirmed agreement in the REBORNE score for non-union bone healing, with an inter-rater reliability of 0.92 and 0.95. Scores through the radiographic evaluation were found equivalent to the CTs at 6 months FU. A CCC of 0.79 was detected against CT. The radiographic scores in the REBORNE bone healing scale correctly classified bone consolidation in 77%, with an accuracy of 83% based on ROC curves.

CONCLUSIONS

The REBORNE score measured with CT or radiographic images was reliable among raters at a follow-up time above 6 months for long bone non-union fractures. The REBORNE scale measured with radiographs proved valid to assess consolidation against CT measurements.

Biomechanics of callus in the bone healing process, determined by specimen-specific finite element analysis

As fractures heal, immature callus formed in the hematoma is calcified by osteoblasts and altered to mature bone. Although the bone strength in the fracture-healing process cannot be objectively measured in clinical settings, bone strength can be predicted by specimen-specific finite element modeling (FEM) of quantitative computed tomography (qCT) scans. FEM predictions of callus strength would enable an objective treatment plan. The present study establishes an equation that converts material properties to bone density and proposes a specimen-specific FEM. In 10 male New Zealand white rabbits, a 10-mm long bone defect was created in the center of the femur and fixed by an external fixator. The callus formed in the defect was extracted after 3-6 weeks, and formed into a (5 × 5 × 5 mm³) cube. The bone density measured by qCT was related to the Young's modulus and the yield stress measured with a mechanical tester. For validation, a 10-mm long bone defect was created in the central femurs of another six New Zealand white rabbits, and fixed by an external fixator. At 3, 4, and 5 weeks, the femur was removed and subjected to Computed tomography (CT) scanning and mechanical testing. A specimen-specific finite element model was created from the CT data. Finally, the bone strength was measured and compared with the experimental value. The bone mineral density σ was significantly and nonlinearly correlated with both the Young's modulus E and the yield stress σ. The material-property conversion equations were E = 0.2391e^8.00ρ and ρ = 30.49σ^2.41. Moreover, the experimental bone strength was significantly linearly correlated with the prospective FEM. We demonstrated the Young's moduli and yield stresses for different bone densities, enabling a FEM of the bone-healing process. An FEM based on these material properties is expected to yield objective clinical judgment criteria.

IFT80 Is Required for Fracture Healing Through Controlling the Regulation of TGF-β Signaling in Chondrocyte Differentiation and Function

Primary cilia are essential cellular organelles that are anchored at the cell surface membrane to sense and transduce signaling. Intraflagellar transport (IFT) proteins are indispensable for cilia formation and function. Although major advances in understanding the roles of these proteins in bone development have been made, the mechanisms by which IFT proteins regulate bone repair have not been identified. We investigated the role of the IFT80 protein in chondrocytes during fracture healing by creating femoral fractures in mice with conditional deletion of IFT80 in chondrocytes utilizing tamoxifen inducible Col2α1-CreER mice. Col2α1cre IFT80f/f mice had smaller fracture calluses than IFT80f/f (control) mice. The max-width and max-callus area were 31% and 48% smaller than those of the control mice, respectively. Col2α1cre IFT80f/f mice formed low-density/porous woven bony tissue with significantly lower ratio of bone volume, Trabecular (Tb) number and Tb thickness, and greater Tb spacing compared to control mice. IFT80 deletion significantly downregulated the expression of angiogenesis markers-VEGF, PDGF and angiopoietin and inhibited fracture callus vascularization. Mechanistically, loss of IFT80 in chondrocytes resulted in a decrease in cilia formation and chondrocyte proliferation rate in fracture callus compared to the control mice. Meanwhile, IFT80 deletion downregulated the TGF-β signaling pathway by inhibiting the expression of TGF-βI, TGF-βR, and phosphorylation of Smad2/3 in the fracture callus. In primary chondrocyte cultures in vitro, IFT80 deletion dramatically reduced chondrocyte proliferation, cilia assembly, and chondrogenic gene expression and differentiation. Collectively, our findings demonstrate that IFT80 and primary cilia play an essential role in fracture healing, likely through controlling chondrocyte proliferation and differentiation, and the TGF-β signaling pathway. © 2019 American Society for Bone and Mineral Research.

Bone Fracture Sensing Using Ultrasound Pitch-Catch Measurements: A Proof-of-Principle Study

The most common imaging method used to diagnose and monitor bone fractures and healing is multiple radiographic images performed by highly trained professionals with expensive equipment that can expose patients to high levels of ionizing radiation. Here we introduce and illustrate proof-of-concept of a potential alternative method for measuring bone fractures: ultrasound pitch-catch measurement technique. Measurements are performed with two piezoelectric transducers, housed in standard orthopedic screws and fixed on either side of simulated fractures, with and without an orthopedic plate, in ex vivo pig limb bones. Using this measurement method, we were able to detect significant differences between uncut and 2-, 5- and 10-mm-deep bone cuts using a two-sided t-test with an α level of 5%.

Radiostereometric Analysis of Stability and Inducible Micromotion After Locked Lateral Plating of Distal Femur Fractures

OBJECTIVES

To evaluate interfragmentary motion over 1 year after distal femoral fracture fixation using radiostereometric analysis (RSA). The secondary aim was to assess whether RSA data are consistent with diagnoses of nonunion.

DESIGN

Prospective cohort study.

SETTING

Level I urban trauma center.

PATIENTS

Sixteen patients between 22 and 89 years of age with distal femoral fracture (OTA/AO type 33).

INTERVENTION

All fractures were treated with a lateral locking plate, and tantalum markers were inserted into the main proximal and distal fracture fragments. RSA was performed at 2, 6, 12, 18, and 52 weeks postoperatively. Both unloaded and loaded RSA measurements were performed.

MAIN OUTCOME MEASUREMENTS

Unloaded fracture migration over time and inducible micromotion at the fracture site in the coronal plane were determined at each follow-up interval.

RESULTS

RSA precision in the coronal plane of interfragmentary motion over time and inducible micromotion were 1.2 and 0.9 mm in the coronal plane, respectively. Two cases required revision surgery for nonunion 1 year postoperatively. For cases of union, unloaded fracture migration stopped being detectable between 12 and 18 weeks, and inducible micromotion was no longer detectable by the 12-week visit. For cases of nonunion, both unloaded migration and inducible micromotion were detected throughout the study period.

CONCLUSIONS

RSA may be used to reliably assess distal femoral fracture healing. RSA revealed differences in cases of union and nonunion by 3 months and more consistently than traditional x-rays.

LEVEL OF EVIDENCE

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

Carbon/PEEK nails: a case-control study of 22 cases

BACKGROUND

Interest around carbon/PEEK plates and nails has been raising. The elastic modulus close to the bone, the high load-carrying capacity and radiolucency make CFR/PEEK materials a potential breakthrough. In the literature, there are abundant data about CFR/PEEK plates in the treatment of proximal humerus, distal radius and distal fibula fractures. In patients affected by bone metastasis, CFR/PEEK nails were proved effective and safe with 12 months of follow-up. Very little is known about performances of CFR/PEEK nails in patients affected by other pathologies.

PURPOSES

The aim of the study was to evaluate safety and efficacy of CFR/PEEK nails in the treatment of various pathological conditions. It was also investigated whatever radiolucency of this nails could lead to a more objective evaluation of bone callus or disease site.

PATIENTS AND METHODS

In the study group were included 20 patients (22 bone segments) who underwent CFR/PEEK nail implantation (eight humerus, one tibia, nine femur and four knee arthrodesis). They were affected by pathological fractures, and in four cases, they required an arthrodesis of the knee. They were retrospectively evaluated considering nail failures and bone callus or disease progression (RUSH scores). Mean follow-up time was 11 months (min 6.8-max 20.3). In the control group were included patients treated with titanium nails in the same institution for the same pathologies. An interclass correlation coefficient (ICC) analysis was performed in both groups considering RUSH scores by two expert surgeon from two institution to assess whether radiolucency could lead to a more objective evaluation of disease or bone callus site.

RESULTS

The ICC of mean values between RUSH scores was 0.882 (IC 95%: 0.702-0.953) in the CFR/PEEK group, while it was 0.778 (IC 95%: 0.41-0.91) in the titanium group. Observers' evaluation showed a significantly higher obscuration by titanium nails than by CFR/PEEK nails. No osteosynthesis failures were reported in both groups.

CONCLUSIONS

Our results confirm the safety of CFR/PEEK nails in the short-medium term. The radiolucency of these materials led our observers to perform more objective evaluations of bone callus formation or disease progression compared to the titanium group given the higher ICC.

LEVEL OF EVIDENCE

III Case-control therapeutic study.

Experimental study on healing of long bone defects treated with fibrin membrane enriched with platelet growth factors and periosteal mesenchymal stem cells in rabbit: Radiographical and histopathological evaluations

The present study was designed to evaluate the effects of platelet growth factors and periosteal mesenchymal stem cells on bone healing process, radiographically. Forty male White New Zealand rabbits in five equal groups were used in this study. A 2 mm full thickness bone defect was made in left radial bone of each animal. In group A (control) the defect was left with no medical intervention. In group B the defect was covered by a fibrin membrane. In group C the defect was covered by a fibrin membrane plus platelet growth factors. In group D the defect was covered by a fibrin membrane plus periosteal mesenchymal stem cells, and in group E the defect was covered by a fibrin membrane enriched with platelet growth factors and periosteal mesenchymal stem cells. Radiological evaluation was done immediately after surgery (week 0) and then at the 1^st, 2^nd, 4^th, 6^th and 8^th weeks after operation. At the end of the eighth week, bone samples were taken to evaluate the histopathology. The radiological and histopathological observations showed a superior bone healing in the groups D and E, after eight weeks in comparison with the groups A, B and C. According to this study, it could be concluded that the platelet growth factors and periosteal mesenchymal stem cells could promote bone regeneration in long bone defects in a rabbit model.

Cyclooxygenase 2 augments osteoblastic but suppresses chondrocytic differentiation of CD90+ skeletal stem cells in fracture sites

Cyclooxygenase 2 (COX-2) is essential for normal tissue repair. Although COX-2 is known to enhance the differentiation of mesenchymal stem cells (MSCs), how COX-2 regulates MSC differentiation into different tissue-specific progenitors to promote tissue repair remains unknown. Because it has been shown that COX-2 is critical for normal bone repair and local COX-2 overexpression in fracture sites accelerates fracture repair, this study aimed to determine the MSC subsets that are targeted by COX-2. We showed that CD90⁺ mouse skeletal stem cells (mSSCs; i.e., CD45^-Tie2^-AlphaV⁺ MSCs) were selectively recruited by macrophage/monocyte chemoattractant protein 1 into fracture sites following local COX-2 overexpression. In addition, local COX-2 overexpression augmented osteoblast differentiation and suppressed chondrocyte differentiation in CD90⁺ mSSCs, which depended on canonical WNT signaling. CD90 depletion data demonstrated that local COX-2 overexpression targeted CD90⁺ mSSCs to accelerate fracture repair. In conclusion, CD90⁺ mSSCs are promising targets for the acceleration of bone repair.

Development of a step counting algorithm using the ambulatory tibia load analysis system for tibia fracture patients

Introduction: Ambulation can be used to monitor the healing of lower extremity fractures. However, the ambulatory behavior of tibia fracture patients remains unknown due to an inability to continuously quantify ambulation outside of the clinic. The goal of this study was to design and validate an algorithm to assess ambulation in tibia fracture patients using the ambulatory tibial load analysis system during recovery, outside of the clinic.

Cell-Based Therapies for the Treatment of Fractures

Ongoing studies investigating fracture healing have uncovered and allowed investigators to gain a better understanding of where the variety of cells, which participate in this process, originate, and how they communicate as well as how they can be enhanced to successfully heal a fracture when the process has slowed or failed completely. This brief review will highlight some of the recent findings regarding the role the immune system in fracture healing and how these cells communicate with each other during the healing process. In addition, two 2 methods that have recently been shown to be promising techniques in supporting fracture when it stalls or reversing the process, when the fracture has failed to heal, will also be described.

Center of pressure in a walking boot shifts posteriorly in patients following lower leg fracture

BACKGROUND

Studies have shown that the ambulatory behavior and amount of weight bearing performed by lower leg fracture patients, increases over time. It is likely that gait features, such as center of pressure (CoP), also change over time.

RESEARCH QUESTION

The purpose of this study was to characterize changes in CoP exhibited by lower leg fracture patients wearing a walking boot during the recovery period.

METHODS

Approximately 2 weeks post-surgery, seven lower leg fracture patients were fitted with a MaxTrax walking boot which was integrated with the Ambulatory Tibia Load Analysis System, an underfoot load monitoring system. Patients wore the walking boot for 2-12 weeks resulting in continuous load data during the recovery period. Ambulation was filtered from the raw data and daily average CoP values were calculated by averaging the CoP vectors from all steps in a given day.

RESULT

In general, the CoP vector varied in both the x and y directions during the initial stages of recovery but was more uniform during the later stages of healing. In 6/7 patients, the CoP in the y direction was closer to the forefoot during the initial stages of healing but shifted posteriorly as time post-surgery increased. The single patient that did not exhibit a posterior shift in CoP was also the only patient to develop a non-union. CoP in the x direction show a less clear trend. CoP in the x direction exhibited a medial shift in 5 patients and a lateral shift in 2 patients.

SIGNIFICANCE

During lower leg fracture recovery in a walking boot, the CoP in the y direction shifts posteriorly as time post-surgery increases and CoP monitoring may become a useful tool to monitor individual patient healing progression.

Effects of mass loading on the viability of assessing the state of healing of a fixated fractured long bone

Introduction

This paper aims to evaluate the effects of mass loading on the healing assessment of an internally fixated femur by vibrational means. The presence of soft tissue surrounding a femur increases damping and mass of a system, and hence affects the vibrational response of a mechanical structure by obscuring the coherent modes. This may compromise vibration-based monitoring strategies in identifying modes associated with fracture healing.

Methods

This paper presents a series of experimental works to address this issue. Two osteotomised composite femurs were internally fixated using a plate-screw system and an intramedullary nail. Soft tissue is approximated by surrounding an artificial Sawbone femur with modelling clay. The femur is excited by an instrumented impact hammer and instrumented with two accelerometers to record bending and torsion modes between 0 and 600 Hz. A 30-min epoxy was applied to simulate the healing of the fractured femur in the osteotomised region. The resonant frequencies and its modes are monitored while union is being formed and a healing index is calculated at various times to quantify the degree of healing.

Results

The results demonstrate that the effect of modelling clay compressed the natural modes along the frequency axis. It is observed that frequency bandwidth in the vicinity of 150 Hz and 500 Hz is sensitive to the state of healing of the fixated femurs, which is due to the increase in stiffness of the osteotomised region. These findings were used to formulate the healing index which assists in identifying the initial, later and complete healing stages in conjunction with the index derivative.

Conclusion

In this study, a two-sensor measurement strategy to quantify fixated femur healing is investigated. It is shown that the mass loading effect did not affect this vibrational analysis method ability to assess the state of healing, and both coherent bending and twisting modes associated with healing were easily identified. The proposed healing index, its derivative, and the cross-spectra are a viable tool for quantitative healing assessment.

Fracture Healing Monitoring by Impact Tests: Single Case Study of a Fractured Tibia With External Fixator

The correct evaluation of the healing process is important to define proper times of fixator dynamization and removal, avoiding refractures. Unfortunately, a quantitative healing assessment is not yet available in clinical practice. The aim of the paper is to prove the feasibility of the mechanical vibration method to assess bone healing in fractures treated with external fixation, in in vivo conditions. The case study was a patient with a tibial fracture treated with a monoaxial fixator. The healing process was monitored for three months through a series of five impact tests. The pins screwed into the bone were used both to excite and measure vibrations. Fracture healing was quantitatively assessed by estimating the resonant frequencies of the leg. The first frequency increased of about 4% per week during the observation period. After the hard callus formation (13 week), also other frequencies increased within the range 1%-6% per week. X-ray observations confirmed the healing progress and proved the method potentiality. In addition, the vibratory response of the leg after fixator removal was evaluated and resulted characterized by five modes in the bandwidth 0-1000 Hz. The results suggest that the vibratory response of a fractured bone treated with external fixation can be a promising indicator for quantitative healing monitoring. The mechanical vibration method could be helpful for reducing X-ray exposure of patients and could be performed more frequently, as desirable for obtaining more attentive monitoring.

Serum 25(OH)D is associated with an altered bone turnover marker response after a hip fracture

C-terminal telopeptide of type I collagen (CTX) and procollagen type 1 N-terminal propeptide (P1NP) are bone turnover markers (BTMs) that are promising surrogate measures of fracture healing; however, it is unknown if their response is affected by other bone healing metabolites. Since 70% of fracture patients are reported to have insufficient serum vitamin D, we sought to determine if serum 25(OH)D levels are associated with differential changes in CTX and P1NP concentrations after hip fracture. This prospective cohort included hip fracture patients 65 years of age or older admitted to one of eight Baltimore-area hospitals. Serum samples were collected at baseline, 2-, 6-, and 12-month post-fracture. A mixed-effects repeated-measures analysis was used to determine the longitudinal association between vitamin D deficiency (25(OH)D < 20 ng/ml) and CTX and P1NP. Baseline lab values were obtained for 296 participants (mean age, 80.8 years; 51% male; 55% 25(OH)D < 20 ng/ml). During the acute fracture healing period P1NP concentrations increased by 14% (95%CI: 7-21%, p < 0.01) while CTX levels did not change (p = 0.07). Both CTX and P1NP decreased below baseline at 6 and 12 months. CTX levels were higher in participants with baseline 25(OH)D < 20 ng/ml (p = 0.01). There was no association between 25(OH)D < 20 ng/ml and P1NP levels over the study duration (p = 0.33). Data from this large, longitudinal cohort support claims that CTX and P1NP concentrations change during fracture healing; however, the differential response of CTX among vitamin D deficient patients highlights important questions for its utility as a reliable surrogate marker of fracture healing. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

Radiologic evaluation of fracture healing

While assessment of fracture healing is a common task for both orthopedic surgeons and radiologists, it remains challenging due to a lack of consensus on imaging and clinical criteria as well as the lack of a true gold standard. Further complicating this evaluation are the wide variations between patients, specific fracture sites, and fracture patterns. Research into the mechanical properties of bone and the process of bone healing has helped to guide the evaluation of fracture union. Development of standardized scoring systems and identification of specific radiologic signs have further clarified the radiologist's role in this process. This article reviews these scoring systems and signs with regard to the biomechanical basis of fracture healing. We present the utility and limitations of current techniques used to assess fracture union as well as newer methods and potential future directions for this field.

Smart bone plates can monitor fracture healing

There are currently no standardized methods for assessing fracture healing, with physicians relying on X-rays which are only useful at later stages of repair. Using in vivo mouse fracture models, we present the first evidence that microscale instrumented implants provide a route for post-operative fracture monitoring, utilizing electrical impedance spectroscopy (EIS) to track the healing tissue with high sensitivity. In this study, we fixed mouse long bone fractures with external fixators and bone plates. EIS measurements taken across two microelectrodes within the fracture gap were able to track longitudinal differences between individual mice with good versus poor healing. We additionally present an equivalent circuit model that combines the EIS data to classify fracture repair states. Lastly, we show that EIS measurements strongly correlated with standard quantitative µCT values and that these correlations validate clinically-relevant operating frequencies for implementation of this technique. These results demonstrate that EIS can be integrated into current fracture management strategies such as bone plating, providing physicians with quantitative information about the state of fracture repair to guide clinical decision-making for patients.

Mechanisms Underlying Normal Fracture Healing and Risk Factors for Delayed Healing

PURPOSE OF REVIEW

Substantial advances have been made in understanding the biological basis of fracture healing. Yet, it is unclear whether the presence of osteoporosis or prior or current osteoporosis therapy influences the healing process or is associated with impaired healing. This review discusses the normal process of fracture healing and the role of osteoporosis and patient-specific factors in relation to fracture repair.

RECENT FINDINGS

The definitive association of osteoporosis to impaired fracture healing remains inconclusive because of limited evidence addressing this point. eStudies testing anabolic agents in preclinical models of ovariectomized animals with induced fractures have produced mostly positive findings showing enhanced fracture repair. Prospective human clinical trials, although few in number and limited in design and to testing only one anabolic agent, have similarly yielded modestly favorable results. Interest is high for exploring currently available osteoporosis therapies for efficacy in fracture repair. Definitive data supporting their efficacy are essential in achieving approval for this indication.

A Quantitative Approach for the Bone-implant Osseointegration Assessment Based on Ultrasonic Elastic Guided Waves

Quantitative and reliable monitoring of osseointegration will help further evaluate the integrity of the orthopaedic construct to promote novel prosthesis design and allow early mobilisation. Quantitative assessment of the degree or the lack of osseointegration is important for the clinical management with the introduction of prosthetic implants to amputees. Acousto-ultrasonic wave propagation has been used in structural health monitoring as well as human health monitoring but so far has not extended to osseointegrated implants or prostheses. This paper presents an ultrasonic guided wave approach to assess the osseointegration of a novel implant. This study explores the potential of integrating structural health monitoring concepts into a new osseointegrated implant. The aim is to demonstrate the extension of acousto-ultrasonic techniques, which have been widely reported for the structural health monitoring of engineering structures, to assess the state of osseointegration of a bone and implant. To illustrate this potential, this paper will report on the experimental findings which investigated the unification of an aluminium implant and bone-like geometry surrogate. The core of the test specimen is filled with silicone and wrapped with plasticine to simulate the highly damped cancellous bone and soft tissue, respectively. To simulate the osseointegration process, a 2-h adhesive epoxy is used to bond the surrogate implant and a bone-like structure. A series of piezoelectric elements are bonded onto the surrogate implant to serve as actuators and sensors. The actuating piezoelectric element on an extramedullary strut is excited with a 1 MHz pulse signal. The reception of the ultrasonic wave by the sensing elements located on the adjacent and furthest struts is used to assess the integration of this implant to the parent bone structure. The study shows an Osseointegration Index can be formulated by using engineering and acousto-ultrasonic methods to measure the unification of a bone and implant. This also highlights a potential quantitative evaluation technique regardless of bone-implant geometry and soft tissue damping.

Early clinical cxperience with the SIGN hip construct: a retrospective case series

Background: As the population ages, the developing world industrializes, and more urban centers emerge, the burden of orthopedic trauma will steadily increase. SIGN Fracture Care International has developed a unique intramedullary device for fixation of hip fractures in low-resource settings lacking fluoroscopy. The purpose of this study is to report the safety profile and complication rate for a consecutive series of hip fracture patients managed using this implant.

Methods: We conducted a retrospective analysis of the first 170 patients treated with the SIGN Hip Construct (SHC) from 2009 to 2014 using the SIGN Online Surgical Database (SOSD). Patients with follow-up greater than 12 weeks and adequate radiographs were included. Data recorded include patient demographics, time-to-surgery, union rate, AO/OTA classification, complications, neck-shaft angle, and clinical outcomes including painless weight bearing and knee flexion greater than 90°.

Results: Of 170 patients, 71 met inclusion criteria with mean follow-up of 39 weeks. Mean age was 49.5 and by WHO, regions were Africa (27), Eastern Mediterranean (21), Western Pacific (17), Americas (3), and Southeast Asia (3). Fractures included intertrochanteric (55), subtrochanteric (7), femoral neck (4), and combined (5). Reduction quality was good in 35 (49%), acceptable in 19 (27%), and poor in 17 (24%). Major complications consisted of varus collapse (6), non- or delayed union (3), intra-articular screw (5), and infection (3). Average postoperative neck-shaft angle was 126° and 119.3° at final follow-up.

Conclusions: This is the first comprehensive report of a novel implant for hip fractures specifically designed for low-resource settings. The early clinical data and outcomes suggest that the SHC can be safely inserted in the absence of fluoroscopy, and facilitates early mobilization while maintaining acceptable reduction until union.

Early Fracture Healing is Delayed in the Col1a2+/G610C Osteogenesis Imperfecta Murine Model

Osteogenesis imperfecta (OI) is a rare heritable skeletal dysplasia mainly caused by type I collagen abnormalities and characterized by bone fragility and susceptibility to fracture. Over 85% of the patients carry dominant mutations in the genes encoding for the collagen type I α1 and α2 chains. Failure of bone union and/or presence of hyperplastic callus formation after fracture were described in OI patients. Here we used the Col1a2^+/G610C mouse, carrying in heterozygosis the α2(I)-G610C substitution, to investigate the healing process of an OI bone. Tibiae of 2-month-old Col1a2^+/G610C and wild-type littermates were fractured and the healing process was followed at 2, 3, and 5 weeks after injury from fibrous cartilaginous tissue formation to its bone replacement by radiography, micro-computed tomography (µCT), histological and biochemical approaches. In presence of similar fracture types, in Col1a2^+/G610C mice an impairment in the early phase of bone repair was detected compared to wild-type littermates. Smaller callus area, callus bone surface, and bone volume associated to higher percentage of cartilage and lower percentage of bone were evident in Col1a2^+/G610C at 2 weeks post fracture (wpf) and no change by 3 wpf. Furthermore, the biochemical analysis of collagen extracted from callus 2 wpf revealed in mutants an increased amount of type II collagen, typical of cartilage, with respect to type I, characteristic of bone. This is the first report of a delay in OI bone fracture repair at the modeling phase.

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

BACKGROUND

The Radiographic Union Score for Tibial fractures (RUST) and the modified version of the system, mRUST, are popular standards for assessing fracture-healing progress with use of radiographs. To our knowledge, this is the first study to experimentally validate the ability of RUST and mRUST to accurately assess bone-healing progression with use of both micro-computed tomography (micro-CT) scanning and biomechanical testing.

METHODS

Adult male rats (n = 29) underwent osteotomy with a midshaft fracture gap repaired with use of a polyetheretherketone plate. Anteroposterior and lateral radiographs were made of the repaired femora prior to rat death at end points of 5, 6, 7, 8, 9, and 17 weeks, and 2 fellowship-trained orthopaedic trauma surgeons independently assigned RUST and mRUST scores to repaired femora. The repaired and intact contralateral femora were then dissected. Bones underwent dissection, micro-CT scanning, and biomechanical torsion testing at the end points.

RESULTS

RUST scores ranged from 5 to 12 and mRUST scores ranged from 5 to 16. Intraclass correlation coefficients (ICCs) were 0.89 (95% confidence interval [CI]: 0.78 to 0.94) for RUST and 0.86 (95% CI: 0.74 to 0.93) for mRUST, which fall within the "almost perfect agreement" category for ICCs. Spearman rank correlation coefficients (RS) showed correlation of RUST (RS range, 0.456 to 0.818) and mRUST (RS range, 0.519 to 0.862) with micro-CT measurements of mineralized callus volume (BV), total callus volume (TV), and BV/TV ratio, but less so with bone mineral density (BMD). Additionally, RUST (RS range, 0.524 to 0.863) and mRUST (RS range, 0.434 to 0.850) were correlated with some biomechanical properties. A RUST score of 10 or an mRUST score of 15 may be considered the threshold above which a plated bone is "healed" because, at these scores, 120% or 140% of failure torque, respectively, was achieved by the repaired femora as compared with the intact contralateral femora.

CONCLUSIONS

RUST and mRUST both show strong statistical correlations with micro-CT and biomechanical parameters.

CLINICAL RELEVANCE

RUST and mRUST scoring systems provide clinicians with validated, reliable, and available tools to assess the progress of fracture-healing.

Is calcium phosphate augmentation a viable option for osteoporotic hip fractures?

The use of calcium phosphate bone cement has been described to allow for retention of reduction. Therefore, we evaluated whether augmentation with resorbable calcium phosphate could improve fracture stability in osteoporotic hip fractures. The results showed that augmentation with calcium phosphate cement significantly improved the stability of intertrochanteric fractures.

INTRODUCTION

The aim with this study was to measure whether augmentation with resorbable calcium phosphate cement could improve fracture stability in osteoporotic hip fractures.

METHODS

We retrospectively reviewed 82 patients who underwent closed reduction and internal fixation with proximal femoral nail (PFN) for unstable intertrochanteric fractures between 2014 and 2017. In 42 of 82 patients, patients were treated with a PFN alone (group I). These patients were compared with 40 patients for whom the same device combined with calcium phosphate cement for augmentation was used (group II). Questionnaire surveys or telephone interviews were conducted and patients completed a self-report Harris hip score (HHS) and visual analog scale (VAS) scores. Radiographic outcomes including mean sliding distance of screw, femoral shortening, and varus collapse were compared. Postoperative complications were compared.

RESULTS

Clinical outcomes at 6 months after surgery were equivalent in both groups. Screw sliding, femoral shortening, and varus collapse were all significantly reduced in the cemented group at the last follow-up (p < 0.001, p = 0.005, p < 0.001, respectively). A total of 9 (21%) complications occurred in group I. In contrast, 2 (5%) complications were seen in group II (p = 0.029).

CONCLUSIONS

Augmentation with calcium phosphate cement significantly improved the stability of intertrochanteric fractures fixed with a PFN and reduced overall failure rates. We believe augmentation with resorbable calcium phosphate cement for osteoporotic hip fractures is a reasonable option in selected patients.

Recent Advances and Future of Gene Therapy for Bone Regeneration

PURPOSE OF REVIEW

The purpose of this review is to discuss the recent advances in gene therapy as a treatment for bone regeneration. While most fractures heal spontaneously, patients who present with fracture nonunion suffer from prolonged pain, disability, and often require additional operations to regain musculoskeletal function.

RECENT FINDINGS

In the last few years, BMP gene delivery by means of electroporation and sonoporation resulted in repair of nonunion bone defects in mice, rats, and minipigs. Ex vivo transfection of porcine mesenchymal stem cells (MSCs) resulted in bone regeneration following implantation in vertebral defects of minipigs. Sustained release of VEGF gene from a collagen-hydroxyapatite scaffold to the mandible of a human patient was shown to be safe and osteoinductive. In conclusion, gene therapy methods for bone regeneration are systematically becoming more efficient and show proof-of-concept in clinically relevant animal models. Yet, on the pathway to clinical use, more investigation is needed to determine the safety aspects of the various techniques in terms of biodistribution, toxicity, and tumorigenicity.

Serum proteomic assessment of the progression of fracture healing

A targeted proteomic analysis of murine serum over a 35-day course of fracture healing was carried out to determine if serum proteomic changes could be used to monitor the biological progression of fracture healing. Transverse, closed femoral fractures where generated and stabilized with intramedullary fixation. A single stranded DNA aptamer-based multiplexed proteomic approach was used to assay 1,310 proteins. The transcriptomic profiles for genes matching the 1,310 proteins were obtained by microarray analysis of callus mRNA. Of the 1,310 proteins analyzed, 850 proteins showed significant differences among the time points (p-value <0.05). Ontology assessment associated these proteins with osteoblasts, monocyte/macrophage lineages, mesenchymal stem cell lines, hepatic tissues, and lymphocytes. Temporal clustering of these data identified proteins associated with inflammation, cartilage formation and bone remodeling stages of healing. VEGF, Wnt, and TGF-βsignaling pathways were restricted to the period of cartilage formation. Comparison of the proteomic and transcriptomic profiles showed that 87.5% of proteins in serum had concordant expression to their mRNA expression in the callus, while 12.5% of the protein and mRNA expression patterns were discordant. The discordant proteins that were elevated in the serum but down regulated in callus mRNA expression were related to clotting functions, allograft rejection, and complement function. While proteins down regulated in the serum and elevated in callus mRNA were associated with osteoblast function, NF-ĸb, and activin signaling. These data show the serum proteome may be used to monitor the different biological stages of fracture healing and have translational potential in assessing human fracture healing. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1153-1163, 2018.

The nail-shaft-axis of the of proximal femoral nail antirotation (PFNA) is an important prognostic factor in the operative treatment of intertrochanteric fractures

INTRODUCTION

Due to the world's aging population, intertrochanteric fractures are frequent. Considering age and comorbidities of most of these patients, it is indispensable to enable early postoperative mobilization of these patients. Intramedullary osteosynthesis with PFN-A is widely used and, in general, considered safe and reliable for the operative treatment of intertrochanteric fractures. However, implant -related complications are reported in 6-21% of all cases. In this study, we are analyzing complication rates and risk factors for implant-related complications.

MATERIALS AND METHODS

All intertrochanteric fractures admitted to our hospital and treated with PFN-A between January 2012 and January 2016 were analysed retrospectively. Radiological analyses of the CCD and the lateral offset on the uninjured side was compared to the CCD initially postoperatively and during follow-up on the operated side. Furthermore, we analysed the tip-apex distance (TAD), blade position in the femoral head and introduced the nail-shaft axis as a new parameter.

RESULTS

Within 101 intertrochanteric fractures included, 16 implant-related complications were encountered (15.84%). Analyses of risk factors for secondary varus displacement of greater than 10° within the follow-up and thus risk for cut-out in the osteosynthesis revealed that etasblished risk factors such as a TAD > 25 mm, reduction in varus and an improper position of the blade were also significant risk factors in our cohort for failure of the osteosynthesis. Moreover, we introduced the nail-shaft axis a new potential risk factor and could show that a too medial or too lateral nail-shaft axis is also significantly associated with secondary varus displacement.

CONCLUSION

When treating introchanteric fractures with PFNA reduction in neutral or even slight valgus, aiming for a TAD < 25 mm and a correct position of the blade within the femoral head reduced the risk for secondary varus displacement significantly. Furthermore, we suggest to aim for a central nail-shaft axis.

Parathyroid hormone analogues for fracture healing: protocol for a systematic review and meta-analysis of randomised controlled trials

INTRODUCTION

Fracture healing is a complex physiological process. Impaired healing will increase the need for care and cause serious complications. Thus, identifying strategies to accelerate the rate of healing, preventing delayed unions and non-unions, is essential. Parathyroid hormone (PTH) is a key systemic regulator of calcium and phosphate metabolism. It has been determined that intermittent administration of PTH and its analogue can exert anabolic effect on bone, increase bone mass and reduce bone loss, leading to an increase in bone formation. Owing to their anabolic effect, there is an increasing interest in its potential in promoting the process of fracture healing. However, in clinical studies, the results are in conflict. This objective of this study is to determine the role of PTH analogues for fracture healing in adults.

METHODS AND ANALYSIS

MEDLINE, EMBASE and Cochrane databases will be searched to identify all randomised controlled trials (RCTs) and quasi-RCTs that compare the different effects between PTH analogues and any other treatments in adults with any type of fracture. The primary outcome is the functional recovery. And the secondary outcomes are fracture union and adverse events. The meta-analysis will be performed using a random effects model. Heterogeneity will be assessed by the P values and I² statistic. And subgroup analyses and sensitivity analyses will be used to explore the heterogeneity. Risk of bias will be assessed using the Cochrane tool and the quality of evidence will be assessed using the Grading of Recommendations Assessment, Development and Evaluation approach.

ETHICS AND DISSEMINATION

Ethical approval is not required because this proposed systematic review and meta-analysis is based on published data, without including confidential personal data or data on interventions on patients. The findings of this study will be published in a peer-reviewed journaland presented at a relevant conference.

PROSPERO REGISTRATION NUMBER

CRD42017062093.

New opportunities for fracture healing detection: Impedance spectroscopy measurements correlate to tissue composition in fractures

Accurate evaluation of fracture healing is important for clinical decisions on when to begin weight-bearing and when early intervention is necessary in cases of fracture nonunion. While the stages of healing involving hematoma, cartilage, trabecular bone, and cortical bone have been well characterized histologically, physicians typically track fracture healing by using subjective physical examinations and radiographic techniques that are only able to detect mineralized stages of bone healing. This exposes the need for a quantitative, reliable technique to monitor fracture healing, and particularly to track healing progression during the early stages of repair. The goal of this study was to validate the use of impedance spectroscopy to monitor fracture healing and perform comprehensive evaluation comparing measurements with histological evidence. Here, we show that impedance spectroscopy not only can distinguish between cadaver tissues involved throughout fracture repair, but also correlates to fracture callus composition over the middle stages of healing in wild-type C57BL/6 mice. Specifically, impedance magnitude has a positive relationship with % trabecular bone and a negative relationship with % cartilage, and the opposite relationships are found when comparing phase angle to these same volume fractions of tissues. With this information, we can quantitatively evaluate how far a fracture has progressed through the healing stages. Our results demonstrate the feasibility of impedance spectroscopy for detection of fracture callus composition and reveals its potential as a method for early detection of bone healing and fracture nonunion. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2620-2629, 2017.

Locking versus non-locking one-third tubular plates for treating osteoporotic distal fibula fractures: a comparative study

INTRODUCTION

Ankle fractures represent the third most common fracture in elderly patients, after hip and wrist fractures. Distal fibula fractures in this population are closely related to osteoporosis, which renders commonly used methods of internal fixation technically demanding and prone to failure. Currently there is a tendency to fix osteoporotic metaphyseal and epiphyseal fractures with locking plates. However, published accounts about the use of this technology in osteoporotic distal fibula fractures are scarce. In this study we compare the results of two groups of patients who underwent surgery for these types of fracture, one group received locking and the other non-locking screws, both using one-third tubular plates.

METHODS

Sixty-two patients, aged over 64 years, underwent surgery for osteoporotic distal fibula fractures between 2011 and 2014. Forty-five of them were stabilized with a non-locking plate and the remaining 17 with a locking plate fixation. Follow-up was performed at 4, 8, 12, 26, and 52 weeks. Results were assessed according to the AOFAS Ankle-Hindfoot Score and radiological criteria for consolidation.

RESULTS

Average time to union and AOFAS scores at 6 and 12 months were similar in both groups, including for the individual categories: function, pain, mobility, and alignment. Only time until partial weight bearing was significantly lower in the locking plate group (4.69 ± 2.63 vs 7.77 ± 4.30, p = 0.03). The most common complications were wound dehiscence and superficial infection (two cases of both).

CONCLUSIONS

Both locking and conventional non-locking plates achieved similar treatment outcomes in this group of osteoporotic patients aged over 64. However, locking plates may offer more benefits in cases that have to take into account immobilization time and concomitant soft-tissue damage.

Humeral shaft fractures: union outcomes in a large cohort

BACKGROUND

Humeral shaft fractures can be managed conservatively or operatively. Fracture characteristics were analyzed to identify patients who would benefit from early operative fixation.

METHODS

We performed a retrospective cohort study of 126 consecutive humeral shaft fractures (2008-2015). Fractures were classified according to fracture type, location, separation, and comminution.

RESULTS

Of 126 patients, 96 were managed conservatively. In 54%, union occurred before 26 weeks, and 13% had delayed union after 26 weeks, whereas 33% did not achieve union. Of 30 patients managed surgically, 63% had union before 26 weeks, 33% had delayed union, and 4% did not achieve union. A statistically significant difference favored operative management. This difference was maintained in specific fracture patterns (simple and spiral fractures) and locations (proximal- or distal-third humeral fractures). Early surgery had a significantly higher union rate than delayed surgery. No difference was present between plate and nail fixation regarding union or neurologic injury. Separation of fragments, open injury, and comminution were not associated with nonunion. A psychiatric history (including psychotic disorders, bipolar disorder, multiple involuntary psychiatric admissions, or dementia) was significantly associated with nonunion after conservative management (P = .016). Two patients with dementia died after their conservatively managed fractures progressed to open injuries.

CONCLUSION

This study found high rates of delayed union and nonunion with conservative management. Patients with a significant psychiatric history may benefit from consideration of operative intervention.