Ultrasonographic appearance of external callus in long-bone fractures

Prevention of Adhesions after Bone Fracture Using a Carboxymethylcellulose and Polyethylene Oxide Composite Gel in Dogs

The formation of adhesions is a common complication following traumatic injuries and surgical procedures, often resulting in pain, stiffness, and loss of function. This study aimed to evaluate the feasibility and safety of using a composite material comprising of carboxymethylcellulose (CMC), polyethylene oxide (PEO), and calcium chloride, for preventing adhesions between muscle and bone during the healing stage, as well as its effect on the bone healing process. Ten healthy purpose-bred laboratory Beagle dogs were randomly subjected to two consecutive operations with a 6-month interval, alternating between left and right forelimbs. On the left forelimb an osteotomy at the ulna was performed, while on the right forelimb the same procedure was supplemented by the application of the anti-adhesion agent in the osteotomy site prior to closure. Clinical, diagnostic imaging, macroscopic, and histological evaluations were performed at various time points. The results showed no significant differences in surgical site perimeter (p = 0.558), lameness (p = 0.227), and radiographic bone healing (p = 0.379) between the two groups. However, the macroscopic (p = 0.006) and histological assessments revealed significantly lower adhesion scores (p = 0.0049) and better healing (p = 0.0102) in the group that received the anti-adhesion agent. These findings suggest that the CMC/PEO composite material is a safe and potentially effective intervention for preventing post-traumatic and post-surgical adhesions in canine patients without compromising bone healing. Further research is warranted to fully characterize the clinical benefits of this approach.

In vivo evaluation of a polyester and fiberglass composite intramedullary nail for femoral osteosynthesis in calves

The objective of this study was to test a composite of polyester resin and fiberglass in the form of an intramedullary nail for osteosynthesis of femoral fractures in calves. The methodology was established based on a previous study that used a bovine femur finite element model to simulate fractures, which were then stabilized by the same nails as proposed in this study. General anesthesia was induced in six calves followed by fracture creation via an oblique incision in the middle third of the femoral diaphysis, and osteosynthesis was immediately performed by retrograde insertion of the composite nail. Locking was achieved by drilling the bone and nail without using a jig and introducing two stainless steel screws proximal and two distal to the fracture line. Five of the six calves achieved complete fracture healing after 60 days. No signs of incompatibility or toxicity of the composite were observed. However, limitations were observed during the surgery, such as difficulty in drilling the nail and trimming the remainder portion of the nail that extended beyond the length of the bone. Small fragments produced by these maneuvers were considered irritating to soft tissues during the postoperative period. It was also found that small cracks in the nail tended to propagate in the form of longitudinal fractures. In conclusion, an intramedullary nail made of polyester resin and fiberglass (a low-cost and easy-to-acquire material) was considered biocompatible and capable of allowing bone healing of femoral fractures in young cattle. However, the development of solutions for the reported limitations is crucial prior to recommending the proposed composite for clinical use.

Ultrasound assessment of humeral shaft nonunion risk: a feasibility and proof of concept study

PURPOSE

To determine the feasibility and reliability of ultrasound in the assessment of humeral shaft fracture healing and estimate the accuracy of 6wk ultrasound in predicting nonunion.

METHODS

Twelve adults with a non-operatively managed humeral shaft fracture were prospectively recruited and underwent ultrasound scanning at 6wks and 12wks post-injury. Seven blinded observers evaluated sonographic callus appearance to determine intra- and inter-observer reliability. Nonunion prediction accuracy was estimated by comparing images for patients that united (n = 10/12) with those that developed a nonunion (n = 2/12).

RESULTS

The mean scan duration was 8 min (5-12) and all patients tolerated the procedure. At 6wks and 12wks, sonographic callus (SC) was present in 11 patients (10 united, one nonunion) and sonographic bridging callus (SBC) in seven (all united). Ultrasound had substantial intra- (weighted kappa: 6wk 0.75; 12wk 0.75) and inter-observer reliability (intraclass correlation coefficient: 6wk 0.60; 12wk 0.76). At 6wks, the absence of SC demonstrated sensitivity 50%, specificity 100%, positive predictive value (PPV) 100% and negative predictive value (NPV) 91% in nonunion prediction (overall accuracy 92%). The absence of SBC demonstrated sensitivity 100%, specificity 70%, PPV 40% and NPV 100% in nonunion prediction (overall accuracy 75%). Of three patients at risk of nonunion (Radiographic Union Score for HUmeral fractures < 8), one had SBC on 6wk ultrasound (that subsequently united) and the others had non-bridging/absent SC (both developed nonunion).

CONCLUSIONS

Ultrasound assessment of humeral shaft fracture healing was feasible, reliable and may predict nonunion. Ultrasound could be useful in defining nonunion risk among patients with reduced radiographic callus formation.

The value of ultrasonography in predicting the outcomes of simple long bone fractures treated by closed intramedullary nail fixation

PURPOSE

Ultrasonography has been used increasingly in orthopaedic practice credited to its low cost, easy accessibility, non-invasiveness, reproducibility, and safety from radiation. The purpose of this study was to test the validity and efficacy of ultrasonography as an adjunct in the assessment of fracture healing in long bones treated with intramedullary interlocking devices and its predictive value in determining the need for a secondary surgical procedure.

METHODS

This was a descriptive longitudinal study of 40 skeletally mature patients who sustained long bone fractures of the tibia or femur treated using intramedullary interlocking nails. Patients with comminuted and segmental fracture patterns were excluded from the study. Each patient was evaluated at 6- and 12-week post-surgery using standard orthogonal radiographs and ultrasonography to assess fracture healing. Patients were then followed up until fracture union. Quantitative data was analyzed using frequency statistics and descriptive data with inferential statistics.

RESULTS

Ultrasonography predicted 87.5% union and 12.5% delayed or non-union as early as 6 weeks after surgery, while radiographs predicted 22.5% union as late as 3 months of follow-up. The sensitivity and specificity of ultrasonography in assessing fracture healing were 100% and 97.2%, respectively, with a positive predictive value of 80.0%. Vascular resistance index was less than 0.5 in all patients who developed delayed or non-union.

CONCLUSION

Ultrasonography is able to predict fracture outcomes much earlier than standardized radiographs with comparable sensitivity and specificity. Vascular resistance index is an objective parameter in assessing callus quality and predicting fracture outcomes.

The Use of Stromal Vascular Fraction in Long Bone Defect Healing in Sheep

The objectives of the present study were to evaluate (a) the feasibility of using stromal vascular fraction (SVF) and nanocrystalline hydroxyapatite (nHA) paste in combination for the treatment of segmental bone defect, (b) the quality of the callus produced, (c) the potential improvement of the autograft technique, and (d) the direct comparison of the biomaterial to the use of autogenous cancellous bone. Unilateral, segmental mid-diaphyseal bone defect was created on the right metatarsus of skeletally mature sheep animals (n = 24) under anesthesia (D0). Residual segments were stabilized by stainless-steel plates and appropriate screws. Defects were managed as follows: group A: use of nHA paste to filling, group B: use of autogenous bone graft mixed with nHA bone paste, placed in defect, group C: use of SVF mixed with nHA bone paste injected into defect, group D: use of bone graft and SVF with nHA paste before apposition in bone defect. SVF had been previously isolated from adipose tissue of the animals intra-operatively after digestion with collagenase solution and neutralization. Animals were evaluated clinically and by X-raying and ultrasonographic examination of the defect, at regular intervals, until D90. Ultrasonographic assessment performed along the length of the defect included calculation of the length of the bone defect and assessment of vascularization. SVF was successfully isolated from group C and D animals, with the average yield being 1.77 × 106 cells. The comparison of clinical scores (based on the 'Kaler scale') on each post-operative day indicated significant differences between the four groups on D1 to D30 (p < 0.01); the median clinical score within group A was 2.5 for D1-D30 and 1 for the entire period; respective scores for other groups were 1.5 (p = 0.07) and 0 (p = 0.033). Differences in radiographic assessment scores were significant for scores obtained on D60 (p = 0.049) and D90 (p = 0.006). There was a significant difference between the four groups in the length of the bone defect, as assessed ultrasonographically, for the entire length of the study; median values were 8, 8.5, 6, and 8 mm for groups A, B, C, and D, respectively (p = 0.008). There was a significance in the differences between median scores obtained during the histopathological examination: 2, 11, 13.5, and 12 for group A, B, C, and D (p = 0.022). There was an inverse correlation between the overall scores of histopathological evaluations and the length of the bone defect (observed on D90) (p < 0.0001) and a correlation between the overall scores and the radiographic assessment scores (obtained on D90) (p < 0.0001). This is the first study in which the efficacy of fresh autologous Stromal Vascular Fraction (SVF) from adipose tissue in enhancing bone healing in a long, weight-bearing, diaphyseal bone was evaluated. It is concluded that the lumbosacral region was an attractive site for harvesting adipose tissue, the use of SVF contributed to faster rehabilitation post-operatively, and SVF significantly enhanced bone formation; in general, the results indicated an osteogenic potential of SVF comparable to the gold standard autologous bone graft.

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

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

Monitoring of fracture healing. Update on current and future imaging modalities to predict union

Fracture nonunion causes considerable patient morbidity and an associated burden to society. Traditional reliance on radiographs to monitor union has limitations as bridging callus of long bone fractures can take three or more months to occur. Computed Tomographic (CT) scanning is becoming increasingly popular and can evaluate bridging callus in the late stages of healing to confirm union. The use of dynamic contrast enhanced Magnetic Resonance Imaging (MRI) and advances in nuclear imaging may yield benefits in the assessment of the infected nonunion. Emerging evidence supports the use of ultrasound to detect bridging callus prior to radiographic confirmation and it may be of use to predict patients at high risk of nonunion. This paper is part of a Supplement supported by The Osteosynthesis and Trauma Care Foundation (OTCF).

Sonographic bridging callus at six weeks following displaced midshaft clavicle fracture can accurately predict healing

AIMS

To evaluate if union of clavicle fractures can be predicted at six weeks post-injury by the presence of bridging callus on ultrasound.

METHODS

Adult patients managed nonoperatively with a displaced mid-shaft clavicle were recruited prospectively. Ultrasound evaluation of the fracture was undertaken to determine if sonographic bridging callus was present. Clinical risk factors at six weeks were used to stratify patients at high risk of nonunion with a combination of Quick Disabilities of the Arm, Shoulder and Hand questionnaire (QuickDASH) ≥ 40, fracture movement on examination, or absence of callus on radiograph.

RESULTS

A total of 112 patients completed follow-up at six months with a nonunion incidence of 16.7% (n = 18/112). Sonographic bridging callus was detected in 62.5% (n = 70/112) of the cohort at six weeks post-injury. If present, union occurred in 98.6% of the fractures (n = 69/70). If absent, nonunion developed in 40.5% of cases (n = 17/42). The sensitivity to predict union with sonographic bridging callus at six weeks was 73.4% and the specificity was 94.4%. Regression analysis found that failure to detect sonographic bridging callus at six weeks was associated with older age, female sex, simple fracture pattern, smoking, and greater fracture displacement (Nagelkerke R2 = 0.48). Of the cohort, 30.4% (n = 34/112) had absent sonographic bridging callus in addition to one or more of the clinical risk factors at six weeks that predispose to nonunion. If one was present the nonunion rate was 35%, 60% with two, and 100% when combined with all three.

CONCLUSION

Ultrasound combined with clinical risk factors can accurately predict fracture healing at six weeks following a displaced midshaft clavicle fracture. Cite this article: Bone Joint Res 2021;10(2):113-121.

Surveillance ultrasonography for conservative treatment of femoral shaft fractures in young children

BACKGROUND

The treatment for femoral shaft fracture (FSF) depends on the age of the patient. While the Pavlik harness is the first choice for patients under 6 months of age, spica casting is preferred for patients over 6 months and under preschool age. Minimally-invasive surgery using elastic stable intramedullary nails is also used in some cases. Skin traction is another treatment choice for some patients who are not candidates for the above methods. This study aimed to evaluate the feasibility of surveillance ultrasonography (US) for the conservative treatment of FSFs in young children.

MATERIALS AND METHODS

This retrospective study included 92 children who were diagnosed with FSF in our hospital from April 2017 to May 2019. After applying the inclusion and exclusion criteria, they were divided into US surveillance (A) and control (B) groups. All patients received conservative treatment by skin traction. For group A, US was used to assess the femur fractures and adjust its reduction on days 1, 3, 5, 7, 10, and 14 until the fracture stabilized. For group B, the fractures were checked by radiographs on days 1, 3, 5, 7, 10, and 14 until the callus appeared. The FSF angle was measured using anteroposterior and lateral radiographs.

RESULTS

All patients were followed up for 18 months. The radiographic evaluation of both groups at the final follow-up showed a significant difference in the FSF angle. The radiograph times and accumulated radiation also showed significant differences between the two groups. However, there was no significant difference in the incidence of complications.

CONCLUSIONS

For FSF closed reduction, surveillance US is a better option compared to radiographs in children treated by skin traction. This approach can significantly decrease exposure to X-ray radiation and improve the reduction.

LEVEL OF EVIDENCE

III.

Decreased Radiation Exposure Using Ultrasound-Assisted Reduction and Fixation of Femoral Shaft Fractures in Children: A Pilot Study

Elastic stable intra-medullary nail procedures have been used to treat femoral fractures in children for some time. Radiation exposure generated by intra-operative radioscopy may induce side effects in children and staff. This study introduces a method of ultrasound-assisted reduction and fixation of femoral fractures in children to decrease radiation exposure. We included 21 children and evaluated displacement of fractures using multi-section scanning. All fracture reductions were performed with ultrasonography. A hyperechoic point with a posterior acoustic shadow can be seen under the proximal and distal segments after the nail passes through the fracture site. Comparison with radioscopy suggests that this is a viable method of reduction and fixation of femoral shaft fractures in children, and can effectively decrease radiation exposure.

Ultrasound and bone: a pictorial review

The assessment of bone mainly relies on standard radiographs, CT, MRI, and bone scintigraphy depending on the anatomic region complexity and clinical scenario. Ultrasound (US), due to different acoustic impedance between soft tissues and the bone cortex, only allows the evaluation of the bone surfaces. Nevertheless, US can be useful in the evaluation of several bone disorders affecting the limbs as a result of its tomographic capabilities and high definition. This pictorial review article summarises our clinical experience in adults and reviews the literature on US bone examination. We first present the US appearance of normal bone and the main congenital anatomic variations, after which we illustrate the US findings of a variety of bone disorders. Although US has limits in bone assessment, its analysis must be a part of every musculoskeletal US examination.

Assessment of union in fractures: Role of Serum Alkaline Phosphatase and Ultrasonography

INTRODUCTION

Fracture union is a fundamental goal in orthopaedics. There is variability in assessment and lack of consensus on reliability of various methods to evaluate progress of union. The purpose of this study was to study the temporal association of non-conventional methods i.e. Serum Alkaline Phosphatase (ALP) and Ultrasound (USG) in assessment of fracture healing with reference to plain radiographs (X-ray).

METHODOLOGY

This was a prospective observational cohort study of 161 adult patients with surgically treated long bone diaphyseal fractures. Plain radiographs, ALP and USG evaluation was done every 6 weekly for 6 months. USG evaluation included assessment of echogenicity and Doppler measurement of Vascular Resistance Index (RI) of callus. Fractures were considered united when X-ray showed bridging callus. ALP and USG changes over the follow-up period were analysed based on the final outcome of fractures.

RESULTS AND CONCLUSION

151 patients showed signs of fracture union at final follow-up. ALP which peaked at 6 weeks in all cases always remained within the laboratory reference range in cases progressing to union; whereas in cases of non-union the levels recorded higher. ALP value was the earliest positive predictor showing progress towards union. Beyond 12 weeks, Hyperechogenicity on Gray scale USG and serial measurement of RI on Doppler USG were found to better confirm progress in fracture union than X-rays. Combined evaluations of ALP and USG appear as promising investigations in assessment of the progress in fracture union.

The Radiographic Union Score for HUmeral fractures (RUSHU) predicts humeral shaft nonunion

AIMS

The primary aim of this study was to develop a reliable, effective radiological score to assess the healing of humeral shaft fractures, the Radiographic Union Score for HUmeral fractures (RUSHU). The secondary aim was to assess whether the six-week RUSHU was predictive of nonunion at six months after the injury.

PATIENTS AND METHODS

Initially, 20 patients with radiographs six weeks following a humeral shaft fracture were selected at random from a trauma database and scored by three observers, based on the Radiographic Union Scale for Tibial fractures system. After refinement of the RUSHU criteria, a second group of 60 patients with radiographs six weeks after injury, 40 with fractures that united and 20 with fractures that developed nonunion, were scored by two blinded observers.

RESULTS

After refinement, the interobserver intraclass correlation coefficient (ICC) was 0.79 (95% confidence interval (CI) 0.67 to 0.87), indicating substantial agreement. At six weeks after injury, patients whose fractures united had a significantly higher median score than those who developed nonunion (10 vs 7; p < 0.001). A receiver operating characteristic curve determined that a RUSHU cut-off of < 8 was predictive of nonunion (area under the curve = 0.84, 95% CI 0.74 to 0.94). The sensitivity was 75% and specificity 80% with a positive predictive value (PPV) of 65% and a negative predictive value of 86%. Patients with a RUSHU < 8 (n = 23) were more likely to develop nonunion than those with a RUSHU ≥ 8 (n = 37, odds ratio 12.0, 95% CI 3.4 to 42.9). Based on a PPV of 65%, if all patients with a RUSHU < 8 underwent fixation, the number of procedures needed to avoid one nonunion would be 1.5.

CONCLUSION

The RUSHU is reliable and effective in identifying patients at risk of nonunion of a humeral shaft fracture at six weeks after injury. This tool requires external validation but could potentially reduce the morbidity associated with delayed treatment of an established nonunion. Cite this article: Bone Joint J 2019;101-B:1300-1306.

What is the role of ultrasound in fracture management?: Diagnosis and therapeutic potential for fractures, delayed unions, and fracture-related infection

Objectives

The aim of this study was to review the current evidence and future application for the role of diagnostic and therapeutic ultrasound in fracture management.

Methods

A review of relevant literature was undertaken, including articles indexed in PubMed with keywords "ultrasound" or "sonography" combined with "diagnosis", "fracture healing", "impaired fracture healing", "nonunion", "microbiology", and "fracture-related infection".

Results

The use of ultrasound in musculoskeletal medicine has expanded rapidly over the last two decades, but the diagnostic use in fracture management is not routinely practised. Early studies have shown the potential of ultrasound as a valid alternative to radiographs to diagnose common paediatric fractures, to detect occult injuries in adults, and for rapid detection of long bone fractures in the resuscitation setting. Ultrasound has also been shown to be advantageous in the early identification of impaired fracture healing; with the advent of 3D image processing, there is potential for wider adoption. Detection of implant-related infection can be improved by ultrasound mediated sonication of microbiology samples. The use of therapeutic ultrasound to promote union in the management of acute fractures is currently a controversial topic. However, there is strong in vitro evidence that ultrasound can stimulate a biological effect with potential clinical benefit in established nonunions, which supports the need for further investigation.

Conclusion

Modern ultrasound image processing has the potential to replace traditional imaging modalities in several areas of trauma practice, particularly in the early prediction of impaired fracture healing. Further understanding of the therapeutic application of ultrasound is required to understand and identify the use in promoting fracture healing.Cite this article: J. A. Nicholson, S. T. J. Tsang, T. J. MacGillivray, F. Perks, A. H. R. W. Simpson. What is the role of ultrasound in fracture management? Diagnosis and therapeutic potential for fractures, delayed unions, and fracture-related infection. Bone Joint Res 2019;8:304-312. DOI: 10.1302/2046-3758.87.BJR-2018-0215.R2.

The diagnostic accuracy of imaging modalities to detect pseudarthrosis after spinal fusion-a systematic review and meta-analysis of the literature

OBJECTIVE

The aim of the study was to determine the diagnostic accuracy of imaging modalities to detect pseudarthrosis after thoracolumbar spinal fusion, with surgical exploration as reference standard.

MATERIALS AND METHODS

A systematic literature search for original studies was performed on the diagnostic accuracy of imaging as index test compared to surgical exploration as reference standard to diagnose pseudarthrosis after thoracolumbar spinal fusion. Diagnostic accuracy values were extracted and methodologic quality of studies was evaluated by the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool. Per modality, clinically comparable studies were included in subgroup meta-analysis and weighted odds ratios (ORs) were calculated using the random effects model.

RESULTS

Fifteen studies were included. Risk of bias was classified as high/unclear in 58% of the studies. Concerns of applicability was classified as high/unclear in 40% of the studies. Four scintigraphy studies including 93 patients in total were pooled to OR = 2.91 (95% confidence interval [CI]: 0.93-9.13). Five studies on plain radiography with 398 patients in total were pooled into OR = 7.07 (95% CI: 2.97-16.86). Two studies evaluating flexion-extension radiography of 75 patients in total were pooled into OR = 4.00 (95% CI: 0.15-105.96). Two studies of 68 patients in total were pooled for CT and yielded OR = 17.02 (95% CI: 6.42-45.10). A single study reporting on polytomography, OR = 10.15 (95% CI 5.49-18.78), was also considered to be an accurate study.

CONCLUSIONS

With a pooled OR of 17.02, CT can be considered the most accurate imaging modality for the detection of pseudarthrosis after thoracolumbar spinal fusion from this review.

Ultrasound for Distal Forearm Fracture: A Systematic Review and Diagnostic Meta-Analysis

Study Objective

To determine the diagnostic accuracy of ultrasound for detecting distal forearm fractures.

Methods

A systematic review and diagnostic meta-analysis was performed according to the PRISMA statement. We searched MEDLINE, Web of Science and the Cochrane Library from inception to September 2015. All prospective studies of the diagnostic accuracy of ultrasound versus radiography as the reference standard were included. We excluded studies with a retrospective design and those with evidence of verification bias. We assessed the methodological quality of the included studies with the QUADAS-2 tool. We performed a meta-analysis of studies evaluating ultrasound to calculate the pooled sensitivity and specificity with 95% confidence intervals (CI95%) using a bivariate model with random effects. Subgroup and sensitivity analysis were used to examine the effect of methodological differences and other study characteristics.

Results

Out of 867 publications we included 16 studies with 1,204 patients and 641 fractures. The pooled test characteristics for ultrasound were: sensitivity 97% (CI95% 93–99%), specificity 95% (CI95% 89–98%), positive likelihood ratio (LR) 20.0 (8.5–47.2) and negative LR 0.03 (0.01–0.08). The corresponding pooled diagnostic odds ratio (DOR) was 667 (142–3,133). Apparent differences were shown for method of viewing, with the 6-view method showing higher specificity, positive LR, and DOR, compared to the 4-view method.

Conclusion

The present meta-analysis showed that ultrasound has a high accuracy for the diagnosis of distal forearm fractures in children when used by proper viewing method. Based on this, ultrasound should be considered a reliable alternative, which has the advantages of being radiation free.

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.

The Role of Ultrasound Imaging of Callus Formation in the Treatment of Long Bone Fractures in Children

Background

In the process of diagnosis and treatment of fractures, an X-ray study is typically performed. In modern medicine very important is the development of new diagnostic methods without adverse effects on the body. One of such techniques is ultrasound imaging. It has a high value in imaging most areas of the body, including the musculoskeletal system. Reports on the use of ultrasound in the evaluation of the callus are rare and this could be a method equivalent to or even better than standard radiographs. The aim of the study was to analyze the correlation of ultrasound with radiographs in imaging of callus formation after fractures of long bones in children and to analyze the correlation of vascular resistance index (RI) and the degree of vascularization of the callus with a subjective radiological assessment of the bone union quality.

Material/Methods

The prospective study was planned to qualify 50 children treated for long bones fractures of the arm, forearm, thigh and lower leg. Ultrasound diagnosis was carried out using a Philips iU22 camera equipped with a linear probe with 17-5-MHz resolution and MSK Superficial program. During ultrasound examination measurements of the callus were performed. Using the Power Doppler callus vascularity was visualized and vascular resistance index (RI) was measured. The same measurements were made within the corresponding area of the healthy limb. The results obtained by ultrasound were compared with radiograph measurements and with the subjective assessment of the callus quality.

Results

Preliminary results were developed on a group of 24 patients, where 28 fractured bones and 28 corresponding healthy bones were examined. Fifteen boys and 9 girls participated in the study. The average age at injury was, respectively, 11 and 9 years. In both groups fractures without displacement were the most frequent. A similar frequency was observed in fractures requiring reposition and subperiosteal fractures. In contrast, fractures with a slight displacement of the fragments, were 3 times more common in girls. Statistical analysis of the measurements of length and width of the callus demonstrated that the differences between results obtained in the ultrasound in comparison with X-rays were not statistically significant. Moreover, preliminary results showed a significantly higher degree of vascularization of the callus than of the healthy periosteum.

Conclusions

Preliminary results indicate the high efficacy of ultrasound in the evaluation of callus formation after fractures of long bones in children and the possibility of its alternative use to X-ray examinations.

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.

Monitoring tissue inflammation and responses to drug treatments in early stages of mice bone fracture using 50 MHz ultrasound

Bone fracture induces moderate inflammatory responses that are regulated by cyclooxygenase-2 (COX-2) or 5-lipoxygenase (5-LO) for initiating tissue repair and bone formation. Only a handful of non-invasive techniques focus on monitoring acute inflammation of injured bone currently exists. In the current study, we monitored in vivo inflammation levels during the initial 2 weeks of the inflammatory stage after mouse bone fracture utilizing 50 MHz ultrasound. The acquired ultrasonic images were correlated well with histological examinations. After the bone fracture in the tibia, dynamic changes in the soft tissue at the medial-posterior compartment near the fracture site were monitored by ultrasound on the days of 0, 2, 4, 7, and 14. The corresponding echogenicity increased on the 2nd, 4th, and 7th day, and subsequently declined to basal levels after the 14th day. An increase of cell death was identified by the positive staining of deoxynucleotidyl transferase dUTP nick end-labeling (TUNEL) assay and was consistent with ultrasound measurements. The increases of both COX-2 and Leukotriene B4 receptor 1 (BLT1, 5-LO-relative receptor), which are regulators for tissue inflammation, in the immunohistochemistry staining revealed their involvement in bone fracture injury. Monitoring the inflammatory response to various non-steroidal anti-inflammatory drugs (NSAIDs) treatments was investigated by treating injured mice with a daily oral intake of aspirin (Asp), indomethacin (IND), and a selective COX-2 inhibitor (SC-236). The Asp treatment significantly reduced fracture-increased echogenicity (hyperechogenicity, p<0.05) in ultrasound images as well as inhibited cell death, and expression of COX-2 and BLT1. In contrast, treatment with IND or SC-236 did not reduce the hyperechogenicity, as confirmed by cell death (TUNEL) and expression levels of COX-2 or BLT1. Taken together, the current study reports the feasibility of a non-invasive ultrasound method capable of monitoring post-fracture tissue inflammation that positively correlates with histological findings. Results of this study also suggest that this approach may be further applied to elucidate the underlying mechanisms of inflammatory processes and to develop therapeutic strategies for facilitating fracture healing.

Ultrasound imaging of long bone fractures and healing with the split-step fourier imaging method

We applied the split-step Fourier imaging method to back-propagate the ultrasound zero-offset wavefields acquired on the bone surface to the sources of scatterers, which are the reflecting interfaces. The method required, as an input, an estimated slowness (reciprocal of half the velocity) model to map the time-dependent sonogram to the depth image, which provides the geometric properties of the interfaces. The slowness was approximated by a depth-dependent term and a first-order spatially varying perturbation. Simulated data sets were used to validate the method. The reconstructed images show proper mapping of the interfaces and the fracture, and a reasonable cortical thickness measurement with 8.3% error. The images also illustrate clearly the bone fracture healing process of a 1-mm-wide 45° inclined crack with different in-filled tissue velocities for various healing stages. Reconstruction of a fractured bone plate using data from an in vitro experiment is also presented. This study suggests that the proposed imaging method has good potential in quantification of bone fractures and monitoring of the fracture healing process.

Ability and limitation of radiographic assessment of fracture healing in rats

The purpose of the present study was to assess whether clinicians are actually able to evaluate the mechanical status of fracture healing from radiograms. Fifteen orthopaedic surgeons evaluated the radiograms of experimentally produced femur fractures in rats and predicted mechanical strength (%) of the affected side compared to the unaffected control side. Following this, actual mechanical strength of the affected and control side was determined by a three-point bending test. The median of the strength in the transverse fracture model predicted from radiograms was 33% (2 weeks), 72% (4 weeks), 88% (6 weeks), 84% (8 weeks), and 89% (12 weeks). The actual measured recovery ratio of mechanical strength (exp/control x 100) was 36%, 76%, 93%, 89%, and 106% in each observation period respectively. The tendency was almost the same in a comminuted fracture model. The mean recovery rate determined by interpretation of the surgeons correlated linearly to the actual measured mechanical strength determined by mechanical testing (R(2): 0.80 in transverse fracture, 0.60 in comminuted fracture). Clinicians demonstrated that a comparatively good evaluation of the mechanical status of fracture healing is possible from radiograms up to approximately 80% recovery. However, they tended to make less accurate, weaker assessments at the final stages. In conclusion, radiograms may be inadequate for evaluation of fracture healing completion.

Qualitative and quantitative assessment of bone fragility and fracture healing using conventional radiography and advanced imaging technologies--focus on wrist fracture

Fractures of the distal radius are one of the most common injuries presented to orthopaedic surgeons. A variety of treatment options are available for the vast array of fracture patterns. Research that explores bone fragility and fracture healing has led to new treatment modalities. As new products and methods are derived to aid in fracture healing it is essential to develop noninvasive and/or nondestructive techniques to assess structural information about bone. Quantitative assessment of macro-structural characteristics such as geometry, and microstructural features such as relative trabecular volume, trabecular spacing, and connectivity may improve our ability to estimate bone strength. Methods for quantitatively assessing macrostructure include (besides conventional radiographs) dual x-ray absorptiometry (DXA) and computed tomography (CT), particularly volumetric quantitative computed tomography (vQCT). Methods for assessing microstructure of trabecular bone include high resolution computed tomography (hrCT), micro computed tomography (microCT), high resolution magnetic resonance (hrMR), and micro magnetic resonance microMR. Volumetric QCT, hrCT and hrMR are generally applicable in vivo; microCT and microMR are principally applicable in vitro. Clinically, the challenges for bone imaging include balancing the advantages of simple bone densitometry versus the more complex architectural features of bone, or the deeper research requirements versus the broader clinical needs.

Correlation of histology of healed fractures and tissue surrounding implants with ultrasonographic and radiographic appearance

OBJECTIVES

To determine if there was histological correlation with ultrasonographic images of healed fractures and implant-associated tissue after fracture treatment by plate osteotomy.

METHODS

Eight adult dogs were included in this retrospective study. Ultrasonography (B-mode and power Doppler) and radiography were performed before plate removal. Surgical biopsies were taken of the fracture site and the tissue adjacent to the plate. These were stained with haematoxylin and eosin to assess histomorphology and bone content and immunolabelled with CD31 to assess vascularity.

RESULTS

Ultrasound and radiographic diagnoses of a healed fracture correlated with histological finding of bone healing. Ultrasonography and histology findings of vascularity were also highly correlated. The tissue surrounding the surgical implants was significantly more vascularised on both ultrasonography and histology than that at the fracture site itself.

CLINICAL RELEVANCE

Ultrasonography can be used to diagnose fracture healing in plated fractures. Power Doppler ultrasonography examination of fracture healing should be performed away from surgical implants to avoid false-positive results of vascularisation.

Outcome assessment in clinical trials of fracture-healing

Although there are numerous methods for defining fracture-healing in clinical studies, no consensus exists regarding the most valid and reliable manner for assessing union or for determining which outcomes are most important. This article summarizes and describes methods for the clinical assessment of fracture-healing and reports results from a systematic review of prevalent definitions currently used in published clinical studies. Conventional radiography and ad hoc clinical definitions continue to be the most commonly used means of assessing fracture-healing in clinical studies. Investigators must improve upon and apply more rigorous outcome assessment in clinical trials, emphasize patient-important outcomes, and report factors that may bias estimated effects.

Ultrasonic monitoring of bone fracture healing

Quantitative ultrasound has attracted significant interest in the evaluation of bone fracture healing. Animal and clinical studies have demonstrated that the propagation velocity across fractured bones can be used as an indicator of healing. Researchers have recently employed computational methods for modeling wave propagation in bones, aiming to gain insight into the underlying mechanisms of wave propagation and to further enhance the monitoring capabilities of ultrasound. In this paper, we review the relevant literature and present the current status of knowledge.

Ultrasonographic assessment of fracture healing after plate osteosynthesis

The goals of this study were to assess the ability of ultrasonography (US) to assess uncomplicated fracture healing and to establish normal images. Twenty-two dogs, ranging in age from 6 to 180 months were studied. Body weight ranged from 2.2 to 60 kg. All fractures were treated by plate osteosynthesis. US (B-mode and power Doppler) and radiography were performed until both were consistent with complete healing. B-mode US was performed in all dogs, and power Doppler US in 14. Fracture healing was judged to be complete based on US earlier than when based on radiography. The tissue immediately adjacent to the plate appeared vascularized on power Doppler images at a time when the tissue at the fracture site had a negative power Doppler exam. US appears useful for assessment of primary fracture healing and power Doppler was useful for detecting vascularization at the fracture site in nonhealed fractures. Power Doppler interrogation should be performed away from any metal implant, as a result from an interrogation adjacent to an implant will not reflect actual vascularization at the fracture site.

Evaluation of nonunion fractures in dogs by use of B-mode ultrasonography, power Doppler ultrasonography, radiography, and histologic examination

OBJECTIVE

To investigate the use of ultrasonography to assess nonunion of fractures in dogs and to compare results of ultrasonography, radiography, and histologic examination.

SAMPLE POPULATION

8 nonunion fractures in 6 dogs (1 each in 5 dogs and 3 in 1 dog); dogs ranged from 7 to 94 months of age and weighed 6 to 30 kg.

PROCEDURES

Diagnostic assessment consisted of complete clinical and orthopedic examinations, radiography, B-mode (brightness mode) ultrasonography, and power Doppler ultrasonography. Biopsy samples were obtained during surgery for histologic examination. They were stained with H&E and immunolabeled by use of anti-CD31 antibodies. Correlations of power Doppler score, power Doppler count, vessel area, and radiographic prediction with the mean number of vessels counted per hpf were derived.

RESULTS

Radiographically, 7 of 8 nonunion fractures were diagnosed as atrophic and were therefore estimated to be nonviable. Vascularity of nonunion fractures during power Doppler ultrasonography ranged from nonvascularized to highly vascularized. Absolute vessel count during histologic examination ranged from 0 to 63 vessels/hpf; 5 nonunion sites had a mean count of > 10 vessels/hpf. Vascularity during power Doppler ultrasonography was highly correlated with the number of vessels per hpf, whereas the correlation between the radiographic assessment and histologic evaluation was low.

CONCLUSIONS AND CLINICAL RELEVANCE

Radiographic prediction of the viability of nonunion fractures underestimated the histologically assessed vascularity of the tissue. Power Doppler ultrasonography provided a more accurate estimation of the viability of the tissue and therefore the necessity for debridement and autografts during revision surgery.

Power Doppler assessment of the neovascularization during uncomplicated fracture healing of long bones in dogs and cats

The aims of this prospective study were to test the feasibility of assessing neovascularization with power Doppler ultrasonography and to investigate its usefulness to follow fracture healing of long bones in dogs and cats. A total of 51 patients (44 dogs and seven cats) were followed. Fracture types differed from simple to comminuted. Therapy ranged from external coaptation to plate osteosynthesis. Patients were followed with radiography, B-mode real time and power Doppler ultrasonography every 2-4 weeks until the fracture was healed. All fractures healed uneventfully. A semi-quantitative numerical score based on signal intensity, vessel area, and number of Doppler signals was assigned and the mean value was used to compare patients and examinations. Time postoperatively was divided into periods of 10 days. No Doppler signal was present during the first 10 days. The mean of the scores was highest between 11 and 20 days postoperatively and the median of the scores peaked between 21 and 30 days. A gradual decrease was seen thereafter. The mean of the scores was zero at 71-80 days and the median at 51-0 days postoperatively for the grouped results. In all positive power Doppler examinations, signals were present in and close to the callus. In seven patients (five dogs and two cats) signals were also present in the peripheral soft tissues in one of the follow up examinations. The normal healing process of fractured bones can be visualized using power Doppler ultrasonography and follows a distinctive time-dependent pattern.

MDCT Versus Digital Radiography in the Evaluation of Bone Healing in Orthopedic Patients

OBJECTIVE

Assessment of bone healing in orthopedic patients is usually monitored by radiographs in two views. The purpose of our study was to compare multiplanar reconstructions from MDCT data sets with digital radiographs for assessing the extent of bone healing.

MATERIALS AND METHODS

Forty-three orthopedic patients (19 women, 24 men) who underwent MDCT and radiography after arthrodesis, fractures, or spinal fusions were included in our study. MDCT was performed on an MX 8000IDT scanner and served as the gold standard. The technical parameters were adapted to the anatomic region. A bone algorithm for reconstruction was used (3,500/600 H). Multiplanar reconstructions were calculated in two orthogonal planes. All patients underwent digital radiography on a Multix FD system in two views according to standard procedures. Multiplanar reconstructions and radiographs were analyzed by two musculoskeletal radiologists in a consensus interpretation to determine bone healing using a semiquantitative approach.

RESULTS

In 27 patients (63%), MDCT and digital radiography were concordant with regard to the extent of bone healing, whereas in 16 patients (37%) the results were not concordant. In eight patients (19%) digital radiographs underestimated the extent of bone healing, whereas in another eight patients (19%) they overestimated the degree of fusion.

CONCLUSION

MDCT using high-quality 2D reformatting is recommended as the primary imaging technique for the evaluation of bone healing.

An ultrasound wearable system for the monitoring and acceleration of fracture healing in long bones

An ultrasound wearable system for remote monitoring and acceleration of the healing process in fractured long bones is presented. The so-called USBone system consists of a pair of ultrasound transducers, implanted into the fracture region, a wearable device and a centralized unit. The wearable device is responsible to carry out ultrasound measurements using the axial-transmission technique and initiate therapy sessions of low-intensity pulsed ultrasound. The acquired measurements and other data are wirelessly transferred from the patient-site to the centralized unit, which is located in a clinical setting. The evaluation of the system on an animal tibial osteotomy model is also presented. A dataset was constructed for monitoring purposes consisting of serial ultrasound measurements, follow-up radiographs, quantitative computed tomography-based densitometry and biomechanical data. The animal study demonstrated the ability of the system to collect ultrasound measurements in an effective and reliable fashion and participating orthopaedic surgeons accepted the system for future clinical application. Analysis of the acquired measurements showed that the pattern of evolution of the ultrasound velocity through healing bones over the postoperative period monitors a dynamic healing process. Furthermore, the ultrasound velocity of radiographically healed bones returns to 80% of the intact bone value, whereas the correlation coefficient of the velocity with the material and mechanical properties of the healing bone ranges from 0.699 to 0.814. The USBone system constitutes the first telemedicine system for the out-hospital management of patients sustained open fractures and treated with external fixation devices.

Ultrasonographic and Radiographic Assessment of Uncomplicated Secondary Fracture Healing of Long Bones in Dogs and Cats

OBJECTIVES

To evaluate the use of ultrasonography (US) to detect bone healing in uncomplicated diaphyseal fractures of dogs and cats, and to compare these observations with detection of healing by radiography (RG).

STUDY DESIGN

Clinical study.

ANIMALS

Dogs (33) and cats (11).

METHODS

RG and brightness mode US were used to follow uncomplicated secondary fracture healing. Fractures were examined at admission and then every 2-4 weeks until healed or implant removal. Temporal differences in definitive detection of healed fracture by imaging technique were examined by species, patient age, bone, and fracture type.

RESULTS

US images obtained during uncomplicated secondary fracture healing were consistent with images of fracture healing described in humans. Mean time to US diagnosis of a healed fracture (mean 46 days) was significantly shorter than by RG (mean 66 days). Mean time until diagnosis of a healed fracture (US and RG) did not differ significantly between open and closed treatment. Patients </=7 months (n=9) healed significantly faster (P<.05) than animals aged 7-36 months (n=24) and animals >36 months (n=11), but there was no significant difference between the latter 2 groups. Diagnosis of a healed simple fracture by US was significantly quicker than for a comminuted fracture (P<.05), but no difference was noted when using RG.

CONCLUSIONS

US can be used to evaluate secondary fracture healing in biologically treated fractures in dogs and cats. US permits detection of a healed fracture earlier than RG.

CLINICAL RELEVANCE

Earlier diagnosis of a healed fracture by US can prevent unnecessarily long limb immobilization and allow earlier dynamization.

Quantitative and qualitative assessment of closed fracture healing using computed tomography and conventional radiography

RATIONALE AND OBJECTIVES

Development of new agents to induce fracture healing requires more sensitive methods to detect early changes in fracture repair. The aims of this study were to determine quantitative and qualitative features of fracture healing using volumetric computed tomography (CT) and to compare them with conventional radiography during the weeks following uncomplicated fractures of the appendicular skeleton.

MATERIALS AND METHODS

39 otherwise healthy men and women with acute, closed fractures of the distal radius, tibial and/or fibular malleoli, or tibial shaft, were enrolled and underwent CT and X-ray imaging at 1, 2, 4, 8, 12, and 16 (tibial shaft only) weeks post fracture. Qualitative assessment included fracture line/margins, fracture gap, external callus appearance, callus-to-cortex ratio, bridging, and radiologic union. Quantitative assessment of CT density changes (Hounsfield units [HU]) in the fracture gap was performed in a subset of 8 fracture patients using MEDx multimodality image analysis software (Sterling,VA). The analysis was performed by drawing free form regions of interest (ROI) covering the fracture gap on baseline (week 1) images and by automated registration of the follow-up images to the baseline co-ordinate system.

RESULTS

The mean time to achieve radiologic union on CT was slightly shorter than on X-rays for radial and tibial shaft fractures (7.3 vs. 8.0 weeks, P = .1). Blurring of the fracture margins and reactive sclerosis were the earliest signs of healing in both modalities. External callus formation was evident in 11 cases and was detected earlier with CT technique. Overall, CT images allowed for more complete and detailed visualization of healing compared with conventional X-rays, which were limited by cast and fixation hardware superimposition, especially in subjects with malleolar and distal radial fractures. Quantitative evaluation showed good intraobserver and interobserver reproducibility and a statistically significant correlation to qualitative changes.

CONCLUSION

Our methods of fracture healing assessment are reliable tools that are able to detect early changes in normal bone healing and may serve as useful additions to subjective image analysis in monitoring fracture healing in clinical trials. CT shows some advantages over conventional X-rays in evaluation of early fracture healing.

Mandibular Reconstruction of a Partial Hemimandibulectomy in a Dog with Severe Malocclusion

OBJECTIVE

To report treatment of severe mandibular malocclusion (after left partial hemimandibulectomy, approximately 7 cm gap).

STUDY DESIGN

Clinical report.

ANIMALS

A 14-month-old golden retriever.

METHODS

After corrective osteotomy of the right horizontal mandibular ramus, normal occlusion was reestablished and temporarily maintained while both mandibles were stabilized by miniplates on the lateral alveolar surface spanning the bilateral mandibular defects (right=1.5 cm, left=7 cm). A fenestrated, monocortical rib graft was positioned beneath the left gingival surface to protect the synthetic graft, which was secured to the miniplate. A mandibular reconstruction plate (right) and a locking mandibular reconstruction plate (left) were secured to the ventral borders of the mandibles. Recombinant bone morphogenetic protein-2 delivered in collagen tricalcium phosphate sponges (rhBMP-2 collagen-TCP sponge) was inserted into both mandibular defects.

RESULTS

New bone formation was identified at 3 months and bony remodeling was evident at recheck examinations up to 4 years. Scintigraphy (6 months, 1 year) confirmed graft revascularization and viability. Bone collected (1 year) from the left defect site had robust new bone formation and evidence of continued remodeling. Only minor complications were encountered during the postoperative period and were easily resolved.

CONCLUSIONS

Reconstruction of a large mandibular defect was facilitated by use of an osteoinductive factor (rhBMP-2 collagen-TCP sponge) as a graft substitute.

CLINICAL RELEVANCE

One-step salvage and reconstruction facilitated by use of an osteoinductive factor, as a graft substitute, may be an alternative strategy for repair of large mandibular defects.

The role of ultrasound in monitoring reconstruction of mandibular continuity defects using osteogenic protein-1 (rhOP-1)

Introducing bone bioengineering concepts in craniofacial surgery demands development of novel imaging strategies, which overcome the shortcomings of radiography such as exposure to ionizing radiation. This study is aimed to investigate the usefulness of ultrasonography (US) in monitoring reconstruction of continuity osteoperiosteal mandibular defects in sheep using rhOP-1. The study was conducted on six adult sheep in which a critical size defect was created at the body of the mandible and was reconstructed using rhOP-1 with type-I collagen as a carrier. Ultrasound images were used to assess onset of bone formation, contour, and surface topography. The results were then compared to corresponding plain radiographs and to post-mortem observations. US showed bone union in all the subjects that concurred with radiographic and post-mortem examinations. US was superior to plain radiography in monitoring early events of ossification. However, it was relatively less efficient in describing the contour of the newly formed bone. It was possible to describe the pattern of bone formation and the dynamic changes in contour and surface topography via US during the follow-up period. In experienced hands, ultrasonography can offer valuable information about bone healing comparable with those obtained by plain radiography. US may replace plain radiography in becoming a routinely used tool for monitoring bone healing in selected sites of the craniofacial skeleton.

Approaches for ultrasonographic evaluation of long bones in the dog

The objective of this study was to identify access portals for ultrasonographic evaluation of canine long bones (humerus, radius, ulna, femur, and tibia). A 7.5 MHz linear transducer was used in five medium-sized dogs (range of 25-35 kg body weight). Good approaches could be identified for all long bones. For the proximal humerus, a cranial portal, and the distal humerus, a lateral portal is suggested. For the radius and ulna, a craniolateral approach seemed to be the best. In the hindlimb, a medial approach for the femur and a craniolateral approach for the tibia were the most effective approaches.

Ultrasound can predict regenerate stiffness in distraction osteogenesis

Assessing the regenerate strength in distraction osteogenesis is crucial for clinical treatment. Several methods have been used to achieve this, including plain radiography, digital radiography, quantitative computed tomography, dual energy xray absorptiometry, and ultrasound. The aim of the current study was to investigate the use of ultrasound in monitoring regenerate formation and to correlate this to biomechanical testing results. An osteotomy was done on the tibia of 30 Yucatan micropigs and an Ilizarov-type half-ring external fixator was mounted. After a 5-day latency period, the tibias were distracted for 10 days and then left to consolidate for 10 days. Seven ultrasound examinations were done during Day 15 through Day 25. After sacrifice, the bone mineral density was measured using quantitative computed tomography. Maximum load and torsional stiffness were measured and correlated with ultrasound measurements and bone mineral density. The ultrasound penetration depth and the bone mineral density correlated closely with torsional stiffness. Ultrasound can be a noninvasive predictor of bone regenerate strength in the early phase of distraction osteogenesis, which may reduce the need for radiographs.

Prediction of mechanical properties of healing fractures using acoustic emission

The objective of this study was to develop a non-destructive method for monitoring fracture healing with acoustic emission (AE). Experimentally produced fractures of the rat femur were tested in tension and in torsion at 4, 6, 8 and 12 weeks after fracture. AE signals were monitored during these mechanical tests. The values for load and torque at the initiation of the AE signal were defined as new mechanical parameters. The apparent density and ash density of the fracture site were also measured at each time period. Tensile strength, tensile stiffness, maximum torque and torsional stiffness of the fracture site increased with time. The AE signal was detected before complete specimen failure. Load and torque for initiation of AE increased proportionally with increasing mechanical properties. The mineral density, however, reached a plateau at 8 weeks, when callus mechanical strength was approximately 50% of control. Load for initiation of AE was strongly correlated with the strength (r = 0.98), stiffness (r = 0.88), and failure strain (r = -0.63) of the callus. Torque for initiation of AE was highly correlated with the maximum torque (r = 0.95) and torsional stiffness (r= 0.93) of the callus. The findings of the present study indicated that some mechanical properties of healing fractures could be estimated by monitoring AE signals.