The reliability of plain radiography in experimental fracture healing

New sensor options for smart fracture implants and wearable devices: Laser-Doppler and white-light spectroscopy allow monitoring of bone regeneration via perfusion measurement

The diagnostic options for monitoring fracture healing are currently limited to methods that expose patients to ionizing radiation, i.e. X-rays or computed tomography. The development of new methods that ideally allow continuous monitoring via smart implants or wearables is urgently needed. Laser-Doppler and white-light spectroscopy, non-invasive light-based methods, could allow to monitor fracture healing via changes in perfusion, but this has never been investigated. It was hypothesized that 1) blood flow (BF) increases before a linear increase in oxygen saturation (SO2) and that 2) SO2 in nonunion cases remains as low as the minimum in union cases. A longitudinal observational cohort study with tibial fracture patients was conducted with additional cross-sectional measurements in nonunion patients and healthy controls. To assess SO2, relative haemoglobin amount (rHb), and BF in the fracture gap, the 'Oxygen to see' (O2C) device was used. Thirty-five patients (20 longitudinal, 15 nonunion) and 28 controls were included. In the longitudinal group, SO2 decreased, reaching a minimum (10 mm: 17.96 days, 16 mm: 15.50 days), and subsequently increased. BF increased to a maximum (10 mm: 12.90 days, 16 mm: 33.51 days), followed by a decrease. The SO2 values in the nonunion group were similar to the minimum values in the longitudinal group. Findings in nonunion patients vs. controls differed only in SO2 (10 mm: p < 0.001, 16 mm: p = 0.038), not in rHb or BF. Laser-Doppler and white-light spectroscopy provide characteristic SO2 and BF trajectories that may serve to monitor fracture healing.

New Parameters Based on Ground Reaction Forces for Monitoring Rehabilitation Following Tibial Fractures and Assessment of Heavily Altered Gait

Instrumented insoles have created opportunities for patient monitoring via long-term recordings of ground reaction forces (GRFs). As the GRF curve is altered in patients after lower-extremity fracture, parameters defined on established curve landmarks often cannot be used to monitor the early rehabilitation process. We aimed to screen several new GRF curve-based parameters for suitability and hypothesized an interrelation with days after surgery. In an observational longitudinal study, data were collected from 13 patients with tibial fractures during straight walking at hospital visits using instrumented insoles. Parametrized curves were fitted and regression analyses conducted to determine the best fit, reflected in the highest R2-value and lowest fitting error. A Wald Test with t-distribution was employed for statistical analysis. Strides were classified as regular or non-regular, and changes in this proportion were analyzed. Among the 12 parameters analyzed, those with the highest R2-values were the mean force between inflection points (R2 = 0.715, p < 0.001, t42 = 9.89), the absolute time between inflection points (R2 = 0.707, p < 0.001, t42 = 9.83), and the highest overall force (R2 = 0.722, p < 0.001, t42 = 10.05). There was a significant increase in regular strides on both injured (R2 = 0.427, p < 0.001, t42 = 5.83) and healthy (R2 = 0.506, p < 0.001, t42 = 6.89) sides. The proposed parameters and assessment of the regular stride ratio enable new options for analyses and monitoring during rehabilitation after tibial shaft fractures. They are robust to pathologic GRF curves, can be determined independently from spatiotemporal coherence, and thus might provide advantages over established methods.

A modified Radiographic Union Score for Tibia (RUST) scoring system for patella fractures treated with osteosynthesis shows excellent intra und interobserver reliability

INTRODUCTION

Patellar fractures are rare at 1% incidence of all fractures. However, they can cause significant functional impairments due to the patella's role in knee joint extension. Current scoring systems lack objectivity in assessing patellar healing. This study aims to validate the Radiographic Union Score for Tibia (RUST) using biplanar radiographs for assessing surgically treated patellar fractures.

MATERIALS AND METHODS

A retrospective analysis of radiological follow-up examinations was conducted on patients undergoing surgical treatment for patellar fractures from January 1st 2013, to June 30th 2023. Thirty patients were randomly selected, yielding 105 postoperative X-rays representing various healing stages. The modified Radiographic Union Score for Tibia (RUST) was applied to these X-rays by three independent trauma surgeons. Radiological follow-up examinations were randomized, pseudonymized, and stored on a hospital server for blinded assessment by three raters. The modified RUST assessed continuity of patellar borders and cortexes, assigning scores based on cortical bridging. Interobserver and intraobserver reliability were evaluated using intraclass correlation coefficients (ICC), adhering to recommended sample size criteria and interpretation guidelines.

RESULTS

The mean modified RUST was 9.1 ± 2.2 points, with scores ranging from 4 to 12 points. The interobserver intraclass correlation coefficient (ICC) was 0.88 (95% CI, 0.81-0.92) and the intraobserver ICC were 0.6 (95% CI, 0.65-0.84), 0.80 (95% CI, 0.71-0.87) and 0.98 (0.98-0.99) respectively, which indicated good to excellent agreement.

CONCLUSIONS

This study validated the Radiographic Union Score for Tibia (RUST) for evaluating bone healing in patellar fractures treated with osteosynthesis, demonstrating good intra- and interobserver reliability. The modified RUST can provide a standardized method for assessing healing in patellar fractures, benefiting both clinical practice and clinical trials.

Near-Infrared Spectroscopy Allows for Monitoring of Bone Fracture Healing via Changes in Oxygenation

Bone fractures are associated with hypoxia, but no longitudinal studies of perfusion measurements in human patients have been reported despite the clinical and research potential. In this longitudinal observational cohort study, the near-infrared spectroscopy (NIRS) device PortaMon was used to assess oxy-(O2Hb), deoxy-(HHb) and total (tHb) haemoglobin, as well as the differences between O2Hb and HHb (HbDiff) and the tissue saturation index (TSI) at three different depths in the fracture gap. Linear mixed effect models were fitted to analyse time effects. One-way ANOVAs were conducted to compare groups. The time points corresponding to minima were calculated via linear regression. In this study, 11 patients with tibial shaft fractures underwent longitudinal measurements. Additionally, 9 patients with diagnosed tibial shaft nonunion and 23 age-matched controls were measured once. In the longitudinal group, all fractures healed, and decreases in O2Hb and HbDiff (all p < 0.05) were observed, with minima occurring 19-21 days after fracture. O2Hb values in nonunion patients did not differ from the minima in longitudinally measured union patients, whereas differences in HHb and tHb were significant (all p < 0.05). Previously, the onset of hypoxia has been assumed to be much faster. The characteristic trajectories of the NIRS parameters O2Hb and HbDiff can be used to fulfil the need for a non-invasive method to monitor fracture healing. These results suggest that NIRS could supplement radiographs and clinical impressions in daily clinical practice and may enable earlier diagnosis of nonunion.

Longitudinal weight and plantar pressure distribution while standing after tibial or malleolar fractures in patients with or without fracture union

Fracture healing is usually monitored by clinical impressions and radiographs. Objective and easy methods for assessing fracture healing without radiation would be beneficial. The aim of this study was to analyse whether weight and plantar pressure while standing can be used to monitor healing of tibial or malleolar fractures and whether these parameters can discriminate between patients with and without union. Thirteen patients were longitudinally assessed during each postoperative clinical visit, of whom two developed a nonunion. Eleven matched healthy controls were assessed once. Additionally, five patients already experiencing nonunion were assessed once at the time of their nonunion diagnosis. All participants performed a standing task for ten seconds with pressure-sensing insoles. Greatest improvements were detected throughout the first three months in patients with union. However, six months after surgery, more than half of the parameters were still significantly different from those of the controls. The weight and pressure distributions did not differ between patients with or without union six months after surgery. A standing task can be used to monitor improvements in weight and pressure distribution throughout the healing process of tibial or malleolar fractures, but lacks potential to discriminate between patients with or without fracture union.

Predicting the Healing of Lower Extremity Fractures Using Wearable Ground Reaction Force Sensors and Machine Learning

Lower extremity fractures pose challenges due to prolonged healing times and limited assessment methods. Integrating wearable sensors with machine learning can help overcome these challenges by providing objective assessment and predicting fracture healing. In this retrospective study, data from a gait monitoring insole on 25 patients with closed lower extremity fractures were analyzed. Continuous underfoot loading data were processed to isolate steps, extract metrics, and feed them into three white-box machine learning models. Decision tree and Lasso regression aided feature selection, while a logistic regression classifier predicted days until fracture healing within a 30-day range. Evaluations via 10-fold cross-validation and leave-one-out validation yielded stable metrics, with the model achieving a mean accuracy, precision, recall, and F1-score of approximately 76%. Feature selection revealed the importance of underfoot loading distribution patterns, particularly on the medial surface. Our research facilitates data-driven decisions, enabling early complication detection, potentially shortening recovery times, and offering accurate rehabilitation timeline predictions.

Methods to accelerate fracture healing - a narrative review from a clinical perspective

Bone regeneration is a complex pathophysiological process determined by molecular, cellular, and biomechanical factors, including immune cells and growth factors. Fracture healing usually takes several weeks to months, during which patients are frequently immobilized and unable to work. As immobilization is associated with negative health and socioeconomic effects, it would be desirable if fracture healing could be accelerated and the healing time shortened. However, interventions for this purpose are not yet part of current clinical treatment guidelines, and there has never been a comprehensive review specifically on this topic. Therefore, this narrative review provides an overview of the available clinical evidence on methods that accelerate fracture healing, with a focus on clinical applicability in healthy patients without bone disease. The most promising methods identified are the application of axial micromovement, electromagnetic stimulation with electromagnetic fields and direct electric currents, as well as the administration of growth factors and parathyroid hormone. Some interventions have been shown to reduce the healing time by up to 20 to 30%, potentially equivalent to several weeks. As a combination of methods could decrease the healing time even further than one method alone, especially if their mechanisms of action differ, clinical studies in human patients are needed to assess the individual and combined effects on healing progress. Studies are also necessary to determine the ideal settings for the interventions, i.e., optimal frequencies, intensities, and exposure times throughout the separate healing phases. More clinical research is also desirable to create an evidence base for clinical guidelines. To make it easier to conduct these investigations, the development of new methods that allow better quantification of fracture-healing progress and speed in human patients is needed.

Design of osteosynthesis plate for detecting bone union using wire natural frequency

We have developed a novel osteosynthesis plate with bone union detection using a wire's natural frequency (BUDWF) to provide the quantitative result of bone union detection. The concept for detecting bone union is measuring the rate of frequency change. The frequency is measured from sound generated from the wire attached to a modified plate. The plate is modified from a Syncera ADLER B0409.10 and attached with 0.3 mm diameter 316L stainless steel wire. The sound generation mechanism was created by PEEK and installed on the plate to generate the sound. The preliminary experiments were conducted on a Sawbones tibia composite mimic. We used the cut Sawbones to create fracture samples with a 0, 0.5, 1-, 2-, and 5-mm gap representing the fractured bone with different gap sizes and prepared uncut Sawbones as a union sample. These samples were tested five times, and the sound was recorded from a condenser microphone and analyzed. We found that the BUDWF can differentiate samples with a fracture gap above 2 mm from the union sample, as the differences in the rates of frequency change between samples with a fracture gap above 2 mm and union samples were statistically significant. However, there was a limitation that the BUDWF plate was still unable to differentiate the 0 mm fracture gap and the union sample in this study.

Long-term continuous instrumented insole-based gait analyses in daily life have advantages over longitudinal gait analyses in the lab to monitor healing of tibial fractures

Introduction: Monitoring changes in gait during rehabilitation allows early detection of complications. Laboratory-based gait analyses proved valuable for longitudinal monitoring of lower leg fracture healing. However, continuous gait data recorded in the daily life may be superior due to a higher temporal resolution and differences in behavior. In this study, ground reaction force-based gait data of instrumented insoles from longitudinal intermittent laboratory assessments were compared to monitoring in daily life. Methods: Straight walking data of patients were collected during clinical visits and in between those visits the instrumented insoles recorded all stepping activities of the patients during daily life. Results: Out of 16 patients, due to technical and compliance issues, only six delivered sufficient datasets of about 12 weeks. Stance duration was longer (p = 0.004) and gait was more asymmetric during daily life (asymmetry of maximal force p < 0.001, loading slope p = 0.001, unloading slope p < 0.001, stance duration p < 0.001). Discussion: The differences between the laboratory assessments and the daily-life monitoring could be caused by a different and more diverse behavior during daily life. The daily life gait parameters significantly improved over time with union. One of the patients developed an infected non-union and showed worsening of force-related gait parameters, which was earlier detectable in the continuous daily life gait data compared to the lab data. Therefore, continuous gait monitoring in the daily life has potential to detect healing problems early on. Continuous monitoring with instrumented insoles has advantages once technical and compliance problems are solved.

Gait analysis: An effective tool to mechanically monitor the bone regeneration of critical-sized defects in tissue engineering applications

INTRODUCTION

Tissue engineering has emerged as an innovative approach to treat critical-size bone defects using biocompatible scaffolds, thus avoiding complex distraction surgeries or limited stock grafts. Continuous regeneration monitoring is essential in critical-size cases due to the frequent appearance of non-unions. This work evaluates the potential clinical use of gait analysis for the mechanical assessment of a tissue engineering regeneration as an alternative to the traditional and hardly conclusive manual or radiological follow-up.

MATERIALS AND METHODS

The 15-mm metatarsal fragment of eight female merino sheep was surgically replaced by a bioceramic scaffold stabilized with an external fixator. Gait tests were performed weekly by making the sheep walk on an instrumented gangway. The evolution of different kinematic and dynamic parameters was analyzed for all the animal's limbs, as well as asymmetries between limbs. Finally, potential correlation in the recovery of the gait parameters was evaluated through the linear regression models.

RESULTS

After surgery, the operated limb has an altered way of carrying body weight while walking. Its loading capacity was significantly reduced as the stance phases were shorter and less impulsive. The non-operated limbs compensated for this mobility deficit. All parameters were normalizing during the consolidation phase while the bone callus was simultaneously mineralizing. The results also showed high levels of asymmetry between the operated limb and its contralateral, which exceeded 150% when analyzing the impulse after surgery. Gait recovery significantly correlated between symmetrical limbs.

CONCLUSIONS

Gait analysis was presented as an effective, low-cost tool capable of mechanically predicting the regeneration of critical-size defects treated by tissue engineering, as comparing regeneration processes or novel scaffolds. Despite the progressive normalization as the callus mineralized, the bearing capacity reduction and the asymmetry of the operated limb were more significant than in other orthopedic alternatives.

Employing direct electromagnetic coupling to assess acute fracture healing: An ovine model assessment

OBJECTIVES

This study explored the efficacy of collecting temporal fracture site compliance data via an advanced direct electromagnetic coupling (DEC) system equipped with a Vivaldi-type antenna, novel calibration technique, and multi-antenna setup (termed maDEC) as an approach to monitor acute fracture healing progress in a translational large animal model. The overarching goal of this approach was to provide insights into the acute healing dynamics, offering a promising avenue for optimizing fracture management strategies.

METHODS

A sample of twelve sheep, subjected to ostectomies and intramedullary nail fixations, was divided into two groups, simulating normal and impaired healing scenarios. Sequential maDEC compliance or stiffness measurements and radiographs were taken from the surgery until euthanasia at four or eight weeks and were subsequently compared with post-sacrifice biomechanical, micro-CT, and histological findings.

RESULTS

The results showed that the maDEC system offered straightforward quantification of fracture site compliance via a multiantenna array. Notably, the rate of change in the maDEC-measured bending stiffness significantly varied between normal and impaired healing groups during both the 4-week (p = 0.04) and 8-week (p = 0.02) periods. In contrast, radiographically derived mRUST healing measurements displayed no significant differences between the groups (p = 0.46). Moreover, the cumulative normalized stiffness maDEC data significantly correlated with post-sacrifice mechanical strength (r2 = 0.80, p < 0.001), micro-CT measurements of bone volume fraction (r2 = 0.60, p = 0.003), and density (r2 = 0.60, p = 0.003), and histomorphometric measurements of new bone area fraction (r2 = 0.61, p = 0.003) and new bone area (r2 = 0.60, p < 0.001).

CONCLUSIONS

These data indicate that the enhanced maDEC system provides a non-invasive, accurate method to monitor fracture healing during the acute healing phase, showing distinct stiffness profiles between normal and impaired healing groups and offering critical insights into the healing process's progress and efficiency.

Assessment of Bone Healing: Opportunities to Improve the Standard of Care

➤ Bone healing is commonly evaluated by clinical examination and serial radiographic evaluation. Physicians should be mindful that personal and cultural differences in pain perception may affect the clinical examination. Radiographic assessment, even with the Radiographic Union Score, is qualitative, with limited interobserver agreement.➤ Physicians may use serial clinical and radiographical examinations to assess bone healing in most patients, but in ambiguous and complicated cases, they may require other methods to provide assistance in decision-making.➤ In complicated instances, clinically available biomarkers, ultrasound, and magnetic resonance imaging may determine initial callus development. Quantitative computed tomography and finite element analysis can estimate bone strength in later callus consolidation phases.➤ As a future direction, quantitative rigidity assessments for bone healing may help patients to return to function earlier by increasing a clinician's confidence in successful progressive healing.

CT-Verified Union Rate Following Arthrodesis of Ankle, Hindfoot, or Midfoot: A Systematic Review

BACKGROUND

Ankle, hindfoot, and midfoot arthrodesis surgeries are standard procedures performed in orthopaedics to treat pain and functional disabilities. Although fusions can effectively improve pain and quality of life, nonunions remain a significant concern for surgeons. With the increased availability of computed tomography (CT), more surgeons rely on this modality for increased accuracy in determining whether a fusion was successful. The objective of this study was to report the rates of CT-confirmed fusion following ankle, hindfoot, or midfoot arthrodesis.

METHODS

A systematic review was performed using EMBASE, Medline, and Cochrane central register from January 2000 to March 2020. Inclusion criteria included studies with adults (<18 years) that received 1 or multiple fusions of the ankle, hindfoot, or midfoot. At least 75% of the study cohort must have been evaluated by CT postoperatively. Basic information was collected, including journal, author, year published, and level of evidence. Other specific information was collected, including patient risk factors, fusion site, surgical technique and fixation, adjuncts, union rates, criteria for successful fusion (%), and time of CT. Once data were collected, a descriptive and comparative analysis was performed.

RESULTS

Included studies (26, n = 1300) had an overall CT-confirmed fusion rate of 78.7% (69.6-87.7). Individual joints had an overall fusion rate of 83.0% (73-92.9). The highest rate of union was in the talonavicular joint (TNJ).

CONCLUSION

These values are lower than previous studies, which found the same procedures to have greater than 90% fusion rates. With these updated figures, as confirmed by CT, surgeons will have better information for clinical decision making and when having informed consent conversations.

Gait Analysis to Monitor Fracture Healing of the Lower Leg

Fracture healing is typically monitored by infrequent radiographs. Radiographs come at the cost of radiation exposure and reflect fracture healing with a time lag due to delayed fracture mineralization following increases in stiffness. Since union problems frequently occur after fractures, better and timelier methods to monitor the healing process are required. In this review, we provide an overview of the changes in gait parameters following lower leg fractures to investigate whether gait analysis can be used to monitor fracture healing. Studies assessing gait after lower leg fractures that were treated either surgically or conservatively were included. Spatiotemporal gait parameters, kinematics, kinetics, and pedography showed improvements in the gait pattern throughout the healing process of lower leg fractures. Especially gait speed and asymmetry measures have a high potential to monitor fracture healing. Pedographic measurements showed differences in gait between patients with and without union. No literature was available for other gait measures, but it is expected that further parameters reflect progress in bone healing. In conclusion, gait analysis seems to be a valuable tool for monitoring the healing process and predicting the occurrence of non-union of lower leg fractures.

Radiographic Evaluation of Distal Radius Fracture Healing by Time: Orthopedist versus Qualitative Assessment of Image Processing

Distal radius fractures are among the most prevalent long-bone fractures in the body. Fracture healing assessment is based on clinical evaluation and radiological examinations. A lack of consensus exists regarding the radiographic criteria for fracture union. Our work examined the commonly used criteria for the assessment of fracture healing. Thirty-two patients, conservatively treated for distal radius fracture, participated in a prospective study. Enrolled patients followed protocol for 26 weeks. Four orthopedic surgeons with similar ranks were asked to evaluate three parameters of radiographic measurements for each set of radiographs, including callus formation, the presence of a fracture line, and bridging of fracture sites or sites of fracture edges in 70 radiographs. Ten patients were eligible for the study. The degree of agreement among surgeons was “good” (Cronbach’s alpha): callus formation—0.8, bridging of fracture sites—0.775, blurring of fracture line gap—0.795. A timeline based on the specific week and grading system was made. Radiographic detection of callus formation was seen after the second film, between 6 and 9 weeks, and an agreement among surgeons was achieved for more than half of the patients for the blurring of the fracture gap. The radiographic healing progression of the distal radius can be detected after 6 and 9 weeks in all three parameters with good agreement between different surgeons. A timeline graph such as the one that was made in this model can be used for the follow-up of patients’ fracture healing or early detection of non-union.

Concepts and clinical aspects of active implants for the treatment of bone fractures

Nonunion is a complication of long bone fractures that leads to disability, morbidity and high costs. Early detection is difficult and treatment through external stimulation and revision surgery is often a lengthy process. Therefore, alternative diagnostic and therapeutic options are currently being explored, including the use of external and internal sensors. Apart from monitoring fracture stiffness and displacement directly at the fracture site, it would be desirable if an implant could also vary its stiffness and apply an intervention to promote healing, if needed. This could be achieved either by a predetermined protocol, by remote control, or even by processing data and triggering the intervention itself (self-regulated 'intelligent' or 'smart' implant). So-called active or smart materials like shape memory alloys (SMA) have opened up opportunities to build active implants. For example, implants could stimulate fracture healing by active shortening and lengthening via SMA actuator wires; by emitting pulses, waves, or electromagnetic fields. However, it remains undefined which modes of application, forces, frequencies, force directions, time durations and periods, or other stimuli such implants should ideally deliver for the best result. The present paper reviews the literature on active implants and interventions for nonunion, discusses possible mechanisms of active implants and points out where further research and development are needed to build an active implant that applies the most ideal intervention. STATEMENT OF SIGNIFICANCE: Early detection of delays during fracture healing and timely intervention are difficult due to limitations of the current diagnostic strategies. New diagnostic options are under evaluation, including the use of external and internal sensors. In addition, it would be desirable if an implant could actively facilitate healing ('Intelligent' or 'smart' implant). Implants could stimulate fracture healing via active shortening and lengthening; by emitting pulses, waves, or electromagnetic fields. No such implants exist to date, but new composite materials and alloys have opened up opportunities to build such active implants, and several groups across the globe are currently working on their development. The present paper is the first review on this topic to date.

Modal Frequencies Associations with Musculoskeletal Components of Human Legs for Extracorporeal Bone Healing Assessment Based on a Vibration Analysis Approach

Reliable and quantitative assessments of bone quality and fracture healing prompt well-optimised patient healthcare management and earlier surgical intervention prior to complications of nonunion and malunion. This study presents a clinical investigation on modal frequencies associations with musculoskeletal components of human legs by using a prototype device based on a vibration analysis method. The findings indicated that the first out-of-plane and coupled modes in the frequency range from 60 to 110 Hz are associated with the femur length, suggesting these modes are suitable quantitative measures for bone evaluation. Furthermore, higher-order modes are shown to be associated with the muscle and fat mass of the leg. In addition, mathematical models are formulated via a stepwise regression approach to determine the modal frequencies using the measured leg components as variables. The optimal models of the first modes consist of only femur length as the independent variable and explain approximately 43% of the variation of the modal frequencies. The subsequent findings provide insights for further development on utilising vibration-based methods for practical bone and fracture healing monitoring.

Vivaldi Antennas for Contactless Sensing of Implant Deflections and Stiffness for Orthopaedic Applications

The implementation of novel coaxial dipole antennas has been shown to be a satisfactory diagnostic platform for the prediction of orthopaedic bone fracture healing outcomes. These techniques require mechanical deflection of implanted metallic hardware (i.e., rods and plates), which, when loaded, produce measurable changes in the resonant frequency of the adjacent antenna. Despite promising initial results, the coiled coaxial antenna design is limited by large antenna sizes and nonlinearity in the resonant frequency data. The purpose of this study was to develop two Vivaldi antennas (a.k.a., "standard" and "miniaturized") to address these challenges. Antenna behaviors were first computationally modeled prior to prototype fabrication. In subsequent benchtop tests, metallic plate segments were displaced from the prototype antennas via precision linear actuator while measuring resultant change in resonant frequency. Close agreement was observed between computational and benchtop results, where antennas were highly sensitive to small displacements of the metallic hardware, with sensitivity decreasing nonlinearly with increasing distance. Greater sensitivity was observed for the miniaturized design for both stainless steel and titanium implants. Additionally, these data demonstrated that by taking resonant frequency data during implant displacement and then again during antenna displacement from the same sample, via linear actuators, that "antenna calibration procedures" could be used to enable a clinically relevant quantification of fracture stiffness from the raw resonant frequency data. These improvements mitigate diagnostic challenges associated with nonlinear resonant frequency response seen in previous antenna designs.

Diagnostic prediction of ovine fracture healing outcomes via a novel multi-location direct electromagnetic coupling antenna

Background

Expedient prediction of adverse bone fracture healing (delayed- or non-union) is necessary to advise secondary treatments for improving healing outcome to minimize patient suffering. Radiographic imaging, the current standard diagnostic, remains largely ineffective at predicting nonunions during the early stages of fracture healing resulting in mean nonunion diagnosis times exceeding six months. Thus, there remains a clinical deficit necessitating improved diagnostic techniques. It was hypothesized that adverse fracture healing expresses impaired biological progression at the fracture site, thus resulting in reduced temporal progression of fracture site stiffness which may be quantified prior to the appearance of radiographic indicators of fracture healing (i.e., calcified tissue).

Methods

A novel multi-location direct electromagnetic coupling antenna was developed to diagnose relative changes in the stiffness of fractures treated by metallic orthopaedic hardware. The efficacy of this diagnostic was evaluated during fracture healing simulated by progressive destabilization of cadaveric ovine metatarsals treated by locking plate fixation (n=8). An ovine in vivo comparative fracture study (n=8) was then utilized to better characterize the performance of the developed diagnostic in a clinically translatable setting. In vivo measurements using the developed diagnostic were compared to weekly radiographic images and postmortem biomechanical, histological, and micro computed tomography analyses.

Results

For all cadaveric samples, the novel direct electromagnetic coupling antenna displayed significant differences at the fracture site (P<0.05) when measuring a fully fractured sample versus partially intact and fully intact fracture states. In subsequent in vivo fracture models, this technology detected significant differences (P<0.001) in fractures trending towards delayed healing during the first 30 days post-fracture.

Conclusions

This technology, relative to traditional X-ray imaging, exhibits potential to greatly expedite clinical diagnosis of fracture nonunion, thus warranting additional technological development.

Measuring Orthopedic Plate Strain to Track Bone Healing Using a Fluidic Sensor Read via Plain Radiography

OBJECTIVE

We describe a fluidic X-ray visualized strain indicator under applied load (X-VISUAL) to quantify orthopedic plate strain and inform rehabilitative care.

METHODS

The sensor comprises a polymeric device with a fluidic reservoir filled with a radio-dense fluid (cesium acetate) and an adjoining capillary wherein the liquid level is measured. A stainless-steel lever attaches to the plate and presses upon the acrylic bulb with a displacement proportional to plate bending strain. The sensor was attached to a plate in a Sawbones composite tibia mimic and a human cadaveric tibia. An osteotomy model (5 mm gap) was used to simulate an unstable fracture, and allograft repair to simulate a stiffer healed fracture. The cadaveric and Sawbones tibia were cyclically loaded five times (0-400 N) using a mechanical test stand, and fluid displacement was measured from plain radiographs.

RESULTS

The sensor displayed reversible and repeatable behavior with a slope of 0.096 mm/kg and fluid level noise of 50-80 micrometer (equivalent to 5-10 N). The allograft-repaired composite fracture was 13 times stiffer than the unstable fracture.

CONCLUSION

An analysis of prior external fracture fixation studies and fatigue curves for internal plates indicates that the threshold for safe weight bearing should be 1/5^th-1/10^th of the initial bending for an unstable fracture. The precision of our device (<2% body weight) should thus be sufficient to track fracture healing from unstable through safe weight bearing.

SIGNIFICANCE

The X-VISUAL fluidic sensor enables orthopedic plate strain quantification to monitor facture healing via X-ray imaging.

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.

Improvements in radiographic and clinical assessment of distal radius fracture healing by FE-estimated bone stiffness

Bone strength determined from finite element (FE) modelling provides an estimate of fracture healing progression following a distal radius fracture (DRF), but how these measures relate to patient-reported outcomes and functional outcomes remains unknown. We hypothesized that changes in bone stiffness and bone mineral density measured using high-resolution peripheral quantitative computed tomography (HR-pQCT) are associated with clinically available measures of functional and patient-reported outcomes. We also aimed to identify which clinical outcome measures best predict fracture stiffness and could therefore be used to inform cast removal.

Participants (n = 30) with stable distal radius fractures were followed for two week intervals from the time of fracture until two months post-fracture, then at three months and six months post-fracture. At each follow-up, participants underwent clinical, radiographic, and functional assessments, as well as had their fractured wrist scanned using HR-pQCT. Recovery of bone stiffness during fracture healing was determined from micro-FE (μFE) models generated from HR-pQCT image data.

During the DRF healing process, significant longitudinal changes were found in μFE-estimated stiffness, patient-reported outcomes, grip strength, range of motion (ROM), tenderness, number of cortices healed based on radiographs, and fracture line visibility (p < 0.05); however, no significant change was detected in HR-pQCT based total bone mineral density. Patient-reported outcomes, such as the Patient-Rated Wrist Evaluation (PRWE) and the Quick Disability of the Arm, Shoulder and Hand (QuickDASH) questionnaire, correlated strongly with μFE-estimated stiffness (0.61 ≥ r_m ≥ 0.66). Based on μFE-estimated stiffness, PRWE and QuickDASH are the best predictors of stiffness recovery (p < 0.05) and may be used to guide duration of cast immobilization in the clinical setting.

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Recovery of fracture stiffness may inform time required for cast immobilization.

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Patient reported outcomes predict rate of fracture stiffness recovery.

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Radiographic outcomes correlate weakly with fracture stiffness.

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Patient reported outcomes may inform duration of cast immobilization.

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.

Ultrasound Radiation Force for the Assessment of Bone Fracture Healing in Children: An In Vivo Pilot Study

Vibrational characteristics of bone are directly dependent on its physical properties. In this study, a vibrational method for bone evaluation is introduced. We propose a new type of quantitative vibro-acoustic method based on the acoustic radiation force of ultrasound for bone characterization in persons with fracture. Using this method, we excited the clavicle or ulna by an ultrasound radiation force pulse which induces vibrations in the bone, resulting in an acoustic wave that is measured by a hydrophone placed on the skin. The acoustic signals were used for wave velocity estimation based on a cross-correlation technique. To further separate different vibration characteristics, we adopted a variational mode decomposition technique to decompose the received signal into an ensemble of band-limited intrinsic mode functions, allowing analysis of the acoustic signals by their constitutive components. This prospective study included 15 patients: 12 with clavicle fractures and three with ulna fractures. Contralateral intact bones were used as controls. Statistical analysis demonstrated that fractured bones can be differentiated from intact ones with a detection probability of 80%. Additionally, we introduce a “healing factor” to quantify the bone healing progress which successfully tracked the progress of healing in 80% of the clavicle fractures in the study.

Towards a Non-Invasive Technique for Healing Assessment of Internally Fixated Femur

The lack of a quantitative method to adequately assess fractured bone healing that has undergone fixation limits prognostic capabilities on patients' optimal return to work. This paper addresses the use of vibrational analysis to monitor the state of healing of a plate-screw fixated femur and supplement the current clinical radiographic assessment. This experimental study involves an osteotomised composite femur specimen enclosed by modelling clay to simulate the damping effect of overlying soft tissues. Epoxy adhesives are applied to the fractured region and to simulate the healing process. With the instrumentation described, the cross-spectrum and coherence are obtained and analysed in the frequency domain over a period of time. The results suggest that it is crucial to analyse the cross-spectrum and proposed healing index to quantitatively assess the stages of healing. The results also show that the mass loading effect due to modelling clay did not influence the proposed healing assessment technique. The findings indicate a potential non-intrusive technique to evaluate the healing of fractured femur by utilising the vibrational responses.

Development and Validation of the Foot Union Scoring Evaluation Tool for Arthrodesis of Foot Structures

Reliable evaluation of osseous consolidation after pedal arthrodesis can be difficult, and the presence or absence of radiographic healing often dictates care. Plain radiographs remain the mainstay imaging tool owing to their cost, efficiency, and low radiation exposure. Applying radiographic parameters that can reliably determine osseous healing is essential. However, currently, no reliable or validated measures are available to determine osseous union of any joint in the foot or ankle. The purpose of the present study was to develop a radiographic healing scoring system that would enhance the diagnostic healing assessment after joint arthrodesis of the foot or ankle. We adapted several existing scales previously validated for fracture healing in the leg, because no study has attempted to apply this to a joint fusion model. A total of 150 cases were evaluated by 6 blinded assessors to test the interrater reliability of the subjective healing assessment compared with the proposed scoring system. The radiographs were classified by the postoperative period: ≤4 weeks, 5 to 12 weeks, and >12 weeks. The initial proposed scale was found to have high interrater reliability but was burdensome. Using a priori item reduction protocols, a limited 5-item scale further improved the internal consistency and reduced the burden. The result was excellent interrater reliability (α = 0.978, standard deviation 0.02, 95% confidence interval 0.96 to 0.99) among all assessors compared with the reduced reliability (α = 0.752) for subjective arthrodesis healing. Intrarater reliability was also found to be superior using a test-retest method. The reliability of this system appeared superior to the subjective assessment of arthrodesis healing, even in the absence of clinical correlates, after foot arthrodesis.

Radiographic Union Scoring Scale for Determining Consolidation Rates in the Calcaneus

The reliable evaluation of osseous consolidation after hindfoot osteotomy can be difficult. Concomitant hindfoot osteotomies often dictate the advancement of weightbearing, and radiographs are the mainstay imaging tool owing to cost, efficiency, and radiation exposure. Understanding the radiographic parameters that can be used to reliably determine osseous healing is paramount. However, currently, no reliable or validated method is available to determine osseous healing of hindfoot osteotomies in irregular bones of the foot. The purpose of the present study was to develop a radiographic healing scoring system that would enhance the diagnostic healing assessment after elective calcaneal osteotomy. We adapted existing orthopedic scales validated for healing in the leg for application in the irregular bones of the foot. A total of 168 cases were evaluated by 6 blinded assessors to test the interrater reliability of subjective healing assessment compared with the proposed scoring system. The radiographs were classified by postoperative period: ≤4 weeks, 5 to 12 weeks, and >12 weeks. The proposed scale had high interrater reliability but was burdensome. Using a priori item reduction protocols, a limited 6-item scale further improved internal consistency and reduced the burden. The result was excellent interrater reliability (α = 0.98, standard deviation 0.02, 95% confidence interval 0.91 to 0.96) among all assessors when using the scoring scale compared with unacceptable reliability (α = 0.438) for subjective osteotomy healing. The reliability of our system appeared superior to that of subjective assessment of osseous healing alone, even in the absence of clinical correlates after osteotomy of the calcaneus.

17β-estradiol improves the efficacy of exploited autologous bone marrow-derived mesenchymal stem cells in non-union radial defect healing: A rabbit model

Exploiting mesenchymal stem cells (MSCs) appears to be an appealing alternative to the traditional clinical approach in the treatment of non-union bone defects. It has been shown that 17β-estradiol improves the osteogenesis and proliferation potential of the MSCs via estrogen receptors. We investigated the effect of 17β-estradiol on exploiting autologous BMSCs (bone marrow-derived MSCs) for the purpose of healing of radial non-union segmental defect in rabbit. Twenty rabbits were divided into 4 experimental groups: 1. Control group; 2. MSC treatment group; 3. 17β-estradiol (E2) treatment group; and 4. E2+MSC treatment group. Isolated BMSCs were seeded in a critical-sized defect on radial mid-diaphysis that was filled with autologous fibrin clot differently in 4 groups: 1. intact fibrin clot (control); 2. Fibrin clot containing MSCs; 3. Estradiol; and 4. E₂ and MSCs. Defect healing was assessed by radiological (week 0, 2, 4, 6, 8 and 10) and histopathological evaluation (week 10). Radiological evaluation data demonstrated that quantities for the E2+MSC group were significantly the greatest in comparison with the other groups at week 4 to 10 inclusive. Moreover, Histopathological evaluation indicated that the E2+MSC group had the highest score which was significantly greater than the E2 group and the control group (P<0.05). In-vivo application of in situ 17β-estradiol provides the seeded BMSCs with improved osteogenic capacity in tandem with an accelerated rate of bone healing. This obviously more qualified approach that yields in a shorter time appears to be promising for the future cell-based clinical treatments of the non-union bone fractures. Exploiting mesenchymal stem cells (MSCs) appears to be an appealing alternative to the traditional clinical approach in the treatment of non-union bone defects. It has been shown that 17β-estradiol improves the osteogenesis and proliferation potential of the MSCs via estrogen receptors. We investigated the effect of 17β-estradiol on exploiting autologous BMSCs (bone marrow-derived MSCs) for the purpose of healing of radial non-union segmental defect in rabbit. Twenty rabbits were divided into 4 experimental groups: 1. Control group; 2. MSC treatment group; 3. 17β-estradiol (E2) treatment group; and 4. E2+MSC treatment group. Isolated BMSCs were seeded in a critical-sized defect on the radial mid-diaphysis that was filled with autologous fibrin clot differently in 4 groups: 1. intact fibrin clot (control); 2. Fibrin clot containing MSCs; 3. Estradiol; and 4. E₂ and MSCs. Defect healing was assessed by radiological (week 0, 2, 4, 6, 8 and 10) and histopathological evaluation (week 10). Radiological evaluation data demonstrated that quantities for the E2+MSC group were significantly the greatest in comparison with the other groups at week 4 to 10 inclusive. Moreover, Histopathological evaluation indicated that the E2+MSC group had the highest score which was significantly greater than the E2 group and the control group (P<0.05). In-vivo application of in situ 17β-estradiol provides the seeded BMSCs with improved osteogenic capacity in tandem with an accelerated rate of bone healing. This obviously more efficient approach that yields in a shorter time appears to be promising for future cell-based clinical treatments of the non-union bone fractures.

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.

Fracture healing: A review of clinical, imaging and laboratory diagnostic options

A fundamental issue in clinical orthopaedics is the determination of when a fracture is united. However, there are no established "gold standards," nor standardized methods for assessing union, which has resulted in significant disagreement among orthopaedic surgeons in both clinical practice and research. A great deal of investigative work has been directed to addressing this problem, with a number of exciting new techniques described. This review provides a brief summary of the burden of nonunion fractures and addresses some of the challenges related to the assessment of fracture healing. The tools currently available to determine union are discussed, including various imaging modalities, biomechanical testing methods, and laboratory and clinical assessments. The evaluation of fracture healing in the setting of both patient care and clinical research is integral to the orthopaedic practice. Weighted integration of several available metrics must be considered to create a composite outcome measure of patient prognosis.

Implantable strain sensor to monitor fracture healing with standard radiography

Current orthopaedic clinical methods do not provide an objective measure of fracture healing or weight bearing for lower extremity fractures. The following report describes a novel approach involving in-situ strain sensors to objectively measure fracture healing. The sensor uses a cantilevered indicator pin that responds to plate bending and an internal scale to demonstrate changes in the pin position on plain film radiographs. The long lever arm amplifies pin movement compared to interfragmentary motion, and the scale enables more accurate measurement of position changes. Testing with a human cadaver comminuted metaphyseal tibia fracture specimen demonstrated over 2.25 mm of reproducible sensor displacement on radiographs with as little as 100 N of axial compressive loading. Finite element simulations determined that pin displacement decreases as the fracture callus stiffens and that pin motion is linearly related to the strain in the callus. These results indicate that an implanted strain sensor is an effective tool to help assess bone healing after internal fixation and could provide an objective clinical measure for return to weight bearing.

In Vivo Correlation of Radiographic Scoring (Radiographic Union Scale for Tibia Fractures) and Biomechanical Data in a Sheep Osteotomy Model: Can We Define Union Radiographically?

OBJECTIVE

To determine (1) the reliability of the standard and modified Radiographic Union Scale for Tibia fractures (RUST) score in a sheep osteotomy model, and (2) the standard and modified RUST scores that represent biomechanical union.

DESIGN

The tibia cortices in a sheep osteotomy model treated by intramedullary nails were radiographically evaluated using standard and modified RUST scores. Scores that correlated with biomechanical union, based on the torsional stiffness of the contralateral tibia, were determined.

INTERVENTION

Two groups of sheep had transverse midshaft osteotomies treated with 10-mm nails after reaming to 11.5 mm. Weight-bearing was allowed as tolerated. Anteroposterior and lateral radiographs were taken at standard intervals from 4 to 12 weeks. The tibial cortices at each time interval were evaluated in a random order by 5 senior orthopaedic trauma surgeons. Each tibia was scored using the standard and modified RUST methods and was assessed for union.

MAIN OUTCOME MEASURES

The intraclass correlation coefficient (ICC) was determined for standard and modified RUST scores at each time interval and for the assessment of union. The percentages of fractures that were defined as united by the surgeons were tabulated by RUST and modified RUST scores. The torsional stiffness of each tibia was tested at 12 weeks and expressed as a percentage of the contralateral side. We considered biomechanical union to be ≥90% of the torsional stiffness of the normal side.

RESULTS

The modified RUST score demonstrated consistently higher ICCs than the standard RUST. All reviewers considered a standard RUST of 10 and a modified RUST of 14 to represent radiographic union. The standard RUST was 10.4 (range: 8.6-12) and modified RUST was 14.2 (range: 12.2-16) for tibiae that were biomechanically united.

CONCLUSIONS

The modified RUST score has a slightly higher ICC than the standard RUST. A standard RUST of 10 and a modified RUST of 14 provide an excellent definition of union based on surgeons' opinion and biomechanical testing for a transverse fracture.

Serum N-terminal telopeptide of type I collagen as an early marker of fracture nonunion in rabbits

The aim of the present study was to establish an experimental animal model of fracture nonunion, and to investigate the changes in serum biomarker concentrations in fracture nonunion. A total of 20 purebred New Zealand rabbits were divided into two group: A bone defect group and a bone fracture group. In the bone defect group, a 15-mm section of bone (including the periosteum) was removed from the mid-radius, and the medullary cavities were closed with bone wax. In the bone fracture group, the mid-radius was fractured. X-rays were taken and blood samples were collected preoperatively and at 2, 3, 4, 5, 6, 7, 8, 10 and 12 weeks after the surgical procedure. The serum concentrations of osteocalcin (OC) and bone-specific alkaline phosphatase (BSAP) served as markers of bone formation, and those of C-terminal telopeptide of type I collagen (CTX), N-terminal telopeptide of type I collagen (NTX) and tartrate-resistant acid phosphatase 5b (TRACP 5b) served as markers of bone resorption. The concentration levels of the markers were measured using a biotin double-antibody sandwich enzyme-linked immunosorbent assay. In the bone defect group, bone callus was observed on X-ray at 2 weeks in three rabbits and the bone calluses stabilized at 5 weeks; however, none of the bones had healed at 8 weeks. In the bone fracture group, the fracture line was distorted at 2 weeks and bone calluses formed at 6-8 weeks. In the bone defect group, the serum BSAP and TRACP 5b concentrations increased following the surgical procedure, peaked at 4 weeks, began to decrease at 5 weeks and stabilized after 6 weeks. The serum OC concentrations did not change significantly following the surgical procedure. The serum CTX concentrations fluctuated during the first 4 weeks, peaked at 5 weeks, then decreased and stabilized after 6 weeks. The serum NTX concentrations fluctuated during the first 4 weeks, were significantly lower at 5 weeks compared with the other time points and stabilized after 6 weeks. These results suggested that a bone nonunion model can be established in New Zealand rabbits by resecting a 15-mm section of bone from the mid-radius prior to bone wax blocking. Measurement of the serum BSAP, CTX, NTX, and TRACP 5b concentrations may be useful for the early detection of bone nonunion. The serum NTX concentrations changed significantly in rabbits with bone nonunion. Further studies are required in order to determine the feasibility of using serum NTX concentrations for the early diagnosis of bone nonunion.

In vivo standardization of bone ultrasonometry of the clavicle

OBJECTIVE

The assessment of fracture union includes physical examination and radiographic imaging, which depend on the examiner's experience. The development of ancillary methods may avoid prolonged treatments and the improper removal of implants. Quantitative bone ultrasonometry has been studied for this purpose and will soon be included in clinical practice. The aims of the present study were to assess the feasibility of using this technique on the clavicle and to standardize its in vivo application.

METHODS

Twenty adult volunteers, including 10 men and 10 women without medical conditions or a previous history of clavicle fracture, underwent axial quantitative ultrasonometric assessment using transducers in various positions (different distances between the transducers and different angulations relative to the clavicle).

RESULTS

Similar values of wave propagation velocity were obtained in the different tested set-ups, which included distinct distances between the transducers and angular positions relative to the clavicle. There were significant differences only in the transducers positioned at 0° and at 5 or 7 cm apart.

CONCLUSIONS

The use of bone ultrasonometry on the clavicle is feasible and the standardization of the technique proposed in this study (transducers placed at 45° and at 7 cm apart) will allow its future application in clinical trials to evaluate the healing process of diaphyseal fractures of the clavicle.

Digital Tomosynthesis to Evaluate Fracture Healing: Prospective Comparison With Radiography and CT

OBJECTIVE

Radiography, currently the standard for postoperative fracture imaging, is limited by overlapping bone and hardware. Tomosynthesis has the benefit of level-by-level imaging without the disadvantages of metal artifacts, increased radiation, and higher costs of CT, the current problem-solving tool. The purpose of this study was to compare tomosynthesis with radiography for evaluating fracture healing.

SUBJECTS AND METHODS

In a prospective study, patients within 1 year of wrist hardware fixation underwent radiography, tomosynthesis, and CT, and the images were interpreted by three readers. The diagnostic accuracy of radiology and tomosynthesis was assessed with ROC curves, and interreader agreement was assessed with Cohen kappa. Fracture scores were correlated with Disabilities of the Arm, Shoulder, and Hand (DASH) and pain scores.

RESULTS

The study participants were 49 patients with 51 fractures. The most common fracture sites were distal radius (43%), scaphoid (18%), and metacarpals (18%). Rates of cortex obscuration by hardware were 2% for CT, 8% for tomosynthesis, and 15% for radiography (p < 0.01 between one modality and another). Detection of cortical fracture lines was significantly better with tomosynthesis than with radiography (AUC, 0.84 vs 0.76, p = 0.01). Inter-reader agreement was moderate for both radiography and tomosynthesis (κ = 0.44 vs 0.55, p = 0.051). There was no significant correlation between fracture scores and DASH scores. There was significant correlation between reported pain levels and both tomosynthesis (r = 0.28, p = 0.03) and CT (r = 0.29, p = 0.04) fracture scores.

CONCLUSION

Tomosynthesis provides diagnostic information superior to that of ra diography in postoperative evaluation of wrist fractures with lower cost and radiation than CT and should be considered in fracture follow-up imaging of other bones.

Using cone-beam CT as a low-dose 3D imaging technique for the extremities: initial experience in 50 subjects

PURPOSE

To prospectively evaluate a dedicated extremity cone-beam CT (CBCT) scanner in cases with and without orthopedic hardware by (1) comparing its imaging duration and image quality to those of radiography and multidetector CT (MDCT) and (2) comparing its radiation dose to that of MDCT.

MATERIALS AND METHODS

Written informed consent was obtained for all subjects for this IRB-approved, HIPAA-compliant study. Fifty subjects with (1) fracture of small bones, (2) suspected intraarticular fracture, (3) fracture at the site of complex anatomy, or (4) a surgical site difficult to assess with radiography alone were recruited and scanned on an extremity CBCT scanner prior to FDA approval. Same-day radiographs were performed in all subjects. Some subjects also underwent MDCT within 1 month of CBCT. Imaging duration and image quality were compared between CBCT and radiographs. Imaging duration, effective radiation dose, and image quality were compared between CBCT and MDCT.

RESULTS

Fifty-one CBCT scans were performed in 50 subjects. Average imaging duration was shorter for CBCT than radiographs (4.5 min vs. 6.6 min, P = 0.001, n = 51) and MDCT (7.6 min vs. 10.9 min, P = 0.01, n = 7). Average estimated effective radiation dose was less for CBCT than MDCT (0.04 mSv vs. 0.13 mSv, P =  .02, n = 7). CBCT images yielded more diagnostic information than radiographs in 23/51 cases and more diagnostic information than MDCT in 1/7 cases, although radiographs were superior for detecting hardware complications.

CONCLUSION

CBCT performs high-resolution imaging of the extremities using less imaging time than radiographs and MDCT and lower radiation dose than MDCT.

Development of a Radiographic Union Score for Determining Osteotomy Union Rates in Long Bones of the Foot

Determining the status of bone healing after osteotomy can be challenging and has implications ranging from clinical decision-making to standardization of research outcomes without the use of computed tomography. To date, no method has been validated for determining osseous healing of an osteotomy site of the long bones of the foot. The purpose of the present study was to develop a radiographic union scoring system that would enhance the diagnostic healing assessment. We adapted existing orthopedic scales that had been validated for healing in the leg for application in the long bones of the foot. One hundred cases were evaluated by 6 blinded assessors to test the inter- and intrarater reliability of the subjective healing assessment compared with the proposed scoring system. The radiographs were classified by postoperative period: ≤4, 5 to 12, and >12 weeks. The proposed scale had a high interrater reliability but was burdensome. Using a priori item reduction protocols, the scale was limited to the 5 items with the best internal consistency, which significantly reduced the burden. The result was excellent interrater reliability (α = 0.87) among all assessors compared with acceptable reliability (α = 0.66) for the subjective osteotomy healing assessment. The intrarater reliability during the subsequent retest phase demonstrated similar relationships, with low agreement (r = 0.38) for subjective healing. Each of the items included in the final scoring scale had moderate to good agreement across all assessors (r = 0.51 to 0.63). The reliability of this system appeared superior to the subjective assessment of osseous healing alone, even in the absence of clinical correlates after an osteotomy in the foot.

Ultrasound monitoring of fracture healing: is this the end of radiography in fracture follow-ups?

OBJECTIVE

To compare the efficacy of ultrasonography (US) versus radiography (XR) in monitoring fracture healing.

DESIGN

Prospective diagnostic follow-up study.

SETTING

Department of Orthopaedics, Level II trauma center.

PATIENTS

Forty-eight acute closed tibial mid diaphysis fracture (OTA 42-A and B) treated by closed reduction and internal fixation with a reamed statically locked tibial interlocking nail between October 2011 and October 2012.

INTERVENTION

Evaluation of fracture healing using both US and XR at 2 week intervals.

MAIN OUTCOME MEASUREMENTS

Ultrasonographic criterion for fracture healing was set as progressive appearance of periosteal callus along with progressive decrease in visibility of nail. Radiographic criterion for fracture union was set as the appearance of bridging callus across all 4 cortices.

RESULTS

Thirty-eight of 48 fractures achieved union, 6 developed a delayed union, whereas 4 went onto nonunion. It was observed that using the above-stated criteria, fracture union was diagnosed at an average of 2 weeks earlier with US as compared with XR. Four of the 6 delayed unions and all nonunions declared themselves much earlier on US versus XR.

CONCLUSIONS

Ultrasonography can provide valuable early information about union and predict delayed and nonunions at an earlier time interval than standard plain radiographs.

LEVEL OF EVIDENCE

Diagnostic level II. See Instructions for authors for a complete description of levels of evidence.

Comparative assessment of bone regeneration by histometry and a histological scoring system / Evaluarea comparativă a regenerării osoase utilizând histometria și un scor de vindecare histologică

Objective: The aim of this research is to evaluate the value of the histological score based on a histological record compared to the histometry for monitoring cranial bone defect healing. Methods: We designed a case -control study with a control and a study group. For a number of 60 CD1 mice representing the study group, a bone defect in the cranial bone was surgically induced and grafted with bone grafts obtained by tissue engineering. Bone grafts were obtained using embryonic stem cells seeded on a scaffold obtained from the red deer antler, and osteogenic basal and complex medium was used as differentiation medium. For other 30 CD1 mice representing the control group, a bone defect in the cranial bone was induced and left to heal without grafts. The regeneration process was assessed after 2 and 4 months using the histological healing scoring system and histometry. Results: The healing score was statistically significantly correlated with the defect size obtained by means of histometry (p<0.001). The evaluation of the parameters comprised in the healing score shows that regeneration of the bone diastasis was the most advanced in the group sacrificed at 4 months after plasty, which employed embryonic stem cells, a complex osteogenic differentiation medium and deer antler as scaffold. Conclusion: histological method based on a histological score is a valuable quantification system of bone regeneration comparable to histometry. Clinical Relevance: This study proves that the presented histological score can help the clinician in the process of bone regeneration evaluation.

Current Options for Determining Fracture Union

Determining whether a bone fracture is healed is one of the most important and fundamental clinical determinations made in orthopaedics. However, there are currently no standardized methods of assessing fracture union, which in turn has created significant disagreement among orthopaedic surgeons in both clinical and research settings. An extensive amount of research has been dedicated to finding novel and reliable ways of determining healing with some promising results. Recent advancements in imaging techniques and introduction of new radiographic scores have helped decrease the amount of disagreement on this topic among physicians. The knowledge gained from biomechanical studies of bone healing has helped us refine our tools and create more efficient and practical research instruments. Additionally, a deeper understanding of the molecular pathways involved in the bone healing process has led to emergence of serologic markers as possible candidates in assessment of fracture union. In addition to our current physician centered methods, patient-centered approaches assessing quality of life and function are gaining popularity in assessment of fracture union. Despite these advances, assessment of union remains an imperfect practice in the clinical setting. Therefore, clinicians need to draw on multiple modalities that directly and indirectly measure or correlate with bone healing when counseling patients.

Validation of the use of radiographic fracture-healing scores in a small animal model

Precise assessment of fracture-healing is vital in both clinical and research settings, where therapies are typically assessed using animal models with union as the study end point. Radiographic scoring systems have been developed for clinical use; however have not been validated in pre-clinical models. Thirty sets of radiographs of rat tibial shaft fractures, treated with external fixation were reviewed by six observers using the Radiographic Union in Tibia (RUST) scale, the Lane & Sandhu score, and an overall impression of union. Fleiss's kappa and Intra-class Correlation Coefficients (ICC) were used to determine reliability. Inter-observer and intra-observer agreement using the general impression score were moderate [kappa; 0.58; 95%CI (0.49-0.65) and 0.66 (0.43-0.89), respectively]. Inter-observer and intra-observer agreement were excellent using both the RUST score [ICC; 0.81 (0.72-0.89) and 0.86 (0.74-0.93), respectively], and Lane & Sandhu score [ICC; 0.88 (0.81-0.93) and 0.90 (0.81-0.95), respectively]. Employing a defined scoring system enhances both the reproducibility and repeatability of bone healing assessment in a small animal model. Routine reporting of fracture scoring methodology should be encouraged to enrich results and facilitate data synthesis across studies.

Do bisphosphonates inhibit direct fracture healing?

Fracture repair occurs by two broad mechanisms: direct healing, and indirect healing with callus formation. The effects of bisphosphonates on fracture repair have been assessed only in models of indirect fracture healing.

A rodent model of rigid compression plate fixation of a standardised tibial osteotomy was used. Ten skeletally mature Sprague–Dawley rats received daily subcutaneous injections of 1 µg/kg ibandronate (IBAN) and ten control rats received saline (control). Three weeks later a tibial osteotomy was rigidly fixed with compression plating. Six weeks later the animals were killed. Fracture repair was assessed with mechanical testing, radiographs and histology.

The mean stress at failure in a four-point bending test was significantly lower in the IBAN group compared with controls (8.69 Nmm-2 (sd 7.63) vs 24.65 Nmm-2 (sd 6.15); p = 0.017). On contact radiographs of the extricated tibiae the mean bone density assessment at the osteotomy site was lower in the IBAN group than in controls (3.7 mmAl (sd 0.75) vs 4.6 mmAl (sd 0.57); p = 0.01). In addition, histological analysis revealed progression to fracture union in the controls but impaired fracture healing in the IBAN group, with predominantly cartilage-like and undifferentiated mesenchymal tissue (p = 0.007).

Bisphosphonate treatment in a therapeutic dose, as used for risk reduction in fragility fractures, had an inhibitory effect on direct fracture healing. We propose that bisphosphonate therapy not be commenced until after the fracture has united if the fracture has been rigidly fixed and is undergoing direct osteonal healing.

Cite this article: Bone Joint J 2013;95-B:1263–8.

The Radiographic Union Score for Hip (RUSH): the use of a checklist to evaluate hip fracture healing improves agreement between radiologists and orthopedic surgeons

OBJECTIVE

The assessment of fracture healing following intertrochanteric fracture fixation is highly variable with no validated standards. Agreement with respect to fracture healing following surgery is important for optimal patient management. The purpose of this study was to (1) assess reliability of intertrochanteric fracture healing assessment and (2) determine if a novel radiographic scoring system for hip fractures improves agreement between radiologists and orthopedic surgeons.

MATERIALS AND METHODS

A panel of three radiologists and three orthopedic surgeons assessed fracture healing in 150 cases of intertrochanteric fractures at two separate time points to determine inter-rater and intra-rater agreement. Reviewers, blinded to the time after injury, first subjectively assessed overall healing using frontal and lateral radiographs for each patient at a single time point. Reviewers then scored each fracture using a Radiographic Union Score for Hip (RUSH) form to determine whether this improves agreement regarding hip fracture healing.

RESULTS

Inter-rater agreement for the overall subjective impression of fracture healing between reviewer groups was only fair (intraclass coefficient [ICC] = 0.34, 95 % CI: 0.11-0.52. Use of the RUSH score improved overall agreement between groups to substantial (ICC = 0.66, 95 % CI: 0.53-0.75). Across reviewers, healing of the medial cortex and overall RUSH score itself demonstrated high correlations with overall perceptions of healing (r = 0.53 and r = 0.72, respectively).

CONCLUSIONS

The RUSH score improves agreement of fracture healing assessment between orthopedic surgeons and radiologists, offers a systematic approach to evaluating intertrochanteric hip fracture radiographs, and may ultimately provide prognostic information that could predict healing outcomes in patients with femoral neck fractures.

The development of a novel model of direct fracture healing in the rat

Objectives

Small animal models of fracture repair primarily investigate indirect fracture healing via external callus formation. We present the first described rat model of direct fracture healing.

Methods

A rat tibial osteotomy was created and fixed with compression plating similar to that used in patients. The procedure was evaluated in 15 cadaver rats and then in vivo in ten Sprague-Dawley rats. Controls had osteotomies stabilised with a uniaxial external fixator that used the same surgical approach and relied on the same number and diameter of screw holes in bone.

Results

Fracture healing occurred without evidence of external callus on plain radiographs. At six weeks after fracture fixation, the mean stress at failure in a four-point bending test was 24.65 N/mm² (sd 6.15). Histology revealed ‘cutting-cones’ traversing the fracture site. In controls where a uniaxial external fixator was used, bone healing occurred via external callus formation.

Conclusions

A simple, reproducible model of direct fracture healing in rat tibia that mimics clinical practice has been developed for use in future studies of direct fracture healing.

Variability in the definition and perceived causes of delayed unions and nonunions: a cross-sectional, multinational survey of orthopaedic surgeons

BACKGROUND

Despite the large number of fracture outcome studies, there remains variability in the definitions of fracture-healing. It is unclear how orthopaedic surgeons are diagnosing and managing delayed unions and nonunions in clinical practice. We aimed to explore the current opinions of orthopaedic surgeons with regard to defining, diagnosing, and treating delayed unions and nonunions in extremity fractures.

METHODS

We developed a survey using previous literature, key informants in the field of orthopaedic surgery, and a sample-to-redundancy strategy. Our final survey contained four sections and twenty-nine questions focusing on demographics and surgical experience, definitions of fracture union, prognostic factors for union, and the need for clinical trials. The Internet-based survey and follow-up e-mails were continued until our a priori sample size of a minimum of 320 completed and eligible responses were collected.

RESULTS

Three hundred and thirty-five surgeons completed the survey. The typical respondent was a North American, male orthopaedic surgeon or consultant over the age of thirty years who had completed trauma fellowship training, worked in an academic practice, supervised residents, and had more than six years of experience in treating orthopaedic injuries. Most surgeons endorsed a lack of standardization in definitions for delayed unions (73%) and nonunions (55%); almost all agreed that defining a delayed union and nonunion should be done on the basis of both radiographic and clinical criteria (88%). Most respondents believed that the degree of soft-tissue injury (approximately 93%), smoking history (approximately 82%), and vascular disease (approximately 76%) increased the risk of healing complications.

CONCLUSIONS

Surgeons use similar prognostic factors to define and assess delayed unions and nonunions, but there is a lack of consensus in the definitions of delayed union and nonunion. The need for standardization and future randomized trials was strongly endorsed.

Quantitative assessment of bone defect healing by multidetector CT in a pig model

OBJECTIVE

To evaluate multidetector CT volumetry in the assessment of bone defect healing in comparison to histopathological findings in an animal model.

MATERIALS AND METHODS

In 16 mini-pigs, a circumscribed tibial bone defect was created. Multidetector CT (MDCT) of the tibia was performed on a 64-row scanner 42 days after the operation. The extent of bone healing was estimated quantitatively by MDCT volumetry using a commercially available software programme (syngo Volume, Siemens, Germany).The volume of the entire defect (including all pixels from -100 to 3,000 HU), the nonconsolidated areas (-100 to 500 HU), and areas of osseous consolidation (500 to 3,000 HU) were assessed and the extent of consolidation was calculated. Histomorphometry served as the reference standard.

RESULTS

The extent of osseous consolidation in MDCT volumetry ranged from 19 to 92% (mean 65.4 ± 18.5%). There was a significant correlation between histologically visible newly formed bone and the extent of osseous consolidation on MDCT volumetry (r = 0.82, P < 0.0001). A significant negative correlation was detected between osseous consolidation on MDCT and histological areas of persisting defect (r = -0.9, P < 0.0001).

CONCLUSION

MDCT volumetry is a promising tool for noninvasive monitoring of bone healing, showing excellent correlation with histomorphometry.