Fracture nonunion: CT assessment with multiplanar reconstruction

3D ultrasound reconstruction of sonographic callus : a novel imaging modality for early evaluation of fracture healing

AIMS

The aim of this study was to establish a reliable method for producing 3D reconstruction of sonographic callus.

METHODS

A cohort of ten closed tibial shaft fractures managed with intramedullary nailing underwent ultrasound scanning at two, six, and 12 weeks post-surgery. Ultrasound capture was performed using infrared tracking technology to map each image to a 3D lattice. Using echo intensity, semi-automated mapping was performed to produce an anatomical 3D representation of the fracture site. Two reviewers independently performed 3D reconstructions and kappa coefficient was used to determine agreement. A further validation study was undertaken with ten reviewers to estimate the clinical application of this imaging technique using the intraclass correlation coefficient (ICC).

RESULTS

Nine of the ten patients achieved union at six months. At six weeks, seven patients had bridging callus of ≥ one cortex on the 3D reconstruction and when present all achieved union. Compared to six-week radiographs, no bridging callus was present in any patient. Of the three patients lacking sonographic bridging callus, one went onto a nonunion (77.8% sensitive and 100% specific to predict union). At 12 weeks, nine patients had bridging callus at ≥ one cortex on 3D reconstruction (100%-sensitive and 100%-specific to predict union). Presence of sonographic bridging callus on 3D reconstruction demonstrated excellent reviewer agreement on ICC at 0.87 (95% confidence interval 0.74 to 0.96).

CONCLUSION

3D fracture reconstruction can be created using multiple ultrasound images in order to evaluate the presence of bridging callus. This imaging modality has the potential to enhance the usability and accuracy of identification of early fracture healing. Cite this article: Bone Joint Res 2021;10(12):759-766.

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).

The accuracy of computed tomography for clavicle non-union evaluation

BACKGROUND

The primary aim of this study is to determine the accuracy of CT scanning when evaluating non-union of the clavicle.

METHODS

A retrospective review was performed of all CT scans undertaken for suspected nonunion of midshaft clavicle fractures over a 10-year period. The influence of scan timing, callus and patient characteristics was evaluated.

RESULTS

One hundred eighty-four CT scans were analysed. No patient was incorrectly diagnosed with union (n = 85). Ninety-nine scans were reported as non-union with inadequate bridging callus, 19 of which were united at operation or on repeat CT imaging and represented delayed unions. Atrophic callus was found in 57 patients and all of which had a confirmed non-union (positive predictive value 100%). A hypertrophic callus was found in 42 patients, all of the delayed unions were found in this group (positive predictive value for non-union 55%, p < 0.001). CT compared to radiographs showed greater inter-observer agreement for union (weighted kappa 0.75 vs. 0.50 respectively). Overall, CT is 100% sensitive and 81.7% specific for non-union diagnosis.

DISCUSSION

CT has excellent accuracy to determine clavicle union but approximately one in five suspected non-unions went onto unite. Hypertrophic callus finding resulted in a delayed union in approximately half of the cases in our study.

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.

Delayed union of a surgically treated fragility fracture of the pelvis: A case report

INTRODUCTION

There are no universally accepted treatment strategies for fragility fractures of the pelvis (FFPs). The incidence of delayed union or non-union of Type IIIa FFP is still unknown.

PRESENTATION OF CASE

We describe a case of delayed union of a Type IIIa FFP. A 96-year-old female patient who lives independently accidentally fell when exiting a car. The diagnosis of Type IIIa FFP with displaced left ilium and left pubic rami fracture. Surgical repair was performed using an anterior intrapelvic approach with constructs made using two reconstruction contoured plates to bridge the medial edge and middle part of the fracture. This case was revealed delayed union. The periodic CT examinations were performed to determine the progress of bone union. The patient returned to most social activities including living independently and the Modified Majeed score was 94 at 12 months post-operation.

DISCUSSION

For the case of TypeⅢa FFP, soft tissue is spread over a wide area. When the fracture site of ilium was exposed, the cortical bone was found to be thin with poor blood flow. There is a possibility that the blood flow was hindered by subperiosteal elevation of the iliacus muscle from the internal iliac fossa in this case.

CONCLUSION

Non-union of the iliac wings is relatively rare following high-energy pelvic ring fractures. The incidence of delayed union or non-union of Type IIIa FFP remains unknown; therefore, careful follow-up of patients who undergo treatment is necessary to reduce the risk of delayed union.

Bifocal treatment for peri-articular femoral nonunions: A retrospective case series review

Aim

This is a retrospective review of complex periarticular femoral nonunions where bone loss from comminution at original fracture, subsequent infection or lysis was identified and treated by radical excision, internal fixation, and concurrent femoral lengthening from a different level.

Material and Method

Sixteen patients with a mean age of 41 years were treated. There were 6 infected nonunions. Ten nonunions were located in the distal femur and the remaining proximal. Case notes and radiograph review were used to determine fracture union, lengthening achieved, and complications. Patient outcome was assessed using the SF-12, Tegner-Lysholm Knee Score, and Oxford Hip Score.

Results

Fracture union was achieved in all patients. The mean lengthening performed was 51 mm (range 30-80) with a fixator time averaging 39 weeks (range 17-80). The bone healing index was 1.9 months/cm. All but 2 patients were restored to within 5 mm of opposite leg length; 1 patient subsequently underwent contralateral limb shortening. The SF-12 had a mean Physical Health Composite Score of 40.0 (22.4-52.9) and a mean Mental Health Composite Score of 49 (30.7-62.0). The Oxford Hip Score was scored at a mean of 39 (21-47) and the Tegner-Lysholm score had a mean of 71 (36-94). There were 3 cases of fracture/deformity from the lengthened bone column (regenerate) and 2 patients required a quadricepsplasty for knee stiffness that was present prior to the treatment for the nonunion.

Conclusion

Bifocal treatment of complex periarticular femoral nonunions offers a single solution for dealing with bone loss, nonunion, and instability. The method is safe and reliable but has, as with all methods involving distraction osteogenesis, a significant complication rate. Despite this caution, the patients' outcomes were satisfactory.

Radiologic evaluation of fracture healing

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

Chemokine analysis as a novel diagnostic modality in the early prediction of the outcome of non-union therapy: a matched pair analysis

BACKGROUND

Despite the regenerative capability of skeletal tissue fracture, non-union is common. Treatment of non-unions remains challenging, and early determination of the outcome is impossible. Chemokines play an important role in promoting the formation of new bone and remodeling existing bone. Despite their importance regarding the regulation of bone biology, the potential of chemokines as biological markers reflecting osseous regeneration is unknown. The purpose of this study was to determine (1) if serum chemokine expression levels correlate with the outcome of non-union surgery and (2) if chemokine expression analysis can be used to identify patients at risk for treatment failure.

METHODS

Non-union patients receiving surgical therapy in our institution between March 2012 and March 2014 were prospectively enrolled in a clinical observer study. Regular clinical and radiological follow-up was conducted for 12 months including collection of blood during the first 12 weeks. Based on the outcome, patients were declared as responders or non-responders to the therapy. To minimize biases, patients were matched (age, sex, body mass index (BMI)) and two groups of patients could be formed: responders (R, n = 10) and non-responders (NR, n = 10). Serum chemokine expression (CCL-2, CCL-3, CCL-4, CXCL-10, CCL-11, and interferon gamma (IFN-γ)) was analyzed using Luminex assays. Data was compared and correlated to the outcome.

RESULTS

CCL-3 expression in NR was significantly higher during the course of the study compared to R (p = 0.002), and the expression pattern of CCL-4 correlated with CCL-3 in both groups (NR: p < 0.001 and r = 0.63). IFN-γ expression in NR was continuously higher than in R (p < 0.001), and utilization of CCL-3 and IFN-γ serum expression levels 2 weeks after the treatment resulted in a predictive model that had an AUC of 0.92 (CI 0.74-1.00).

CONCLUSION

Serum chemokine expression analysis over time is a valid and promising diagnostic tool. The chemokine expression pattern correlates with the outcome of the Masquelet therapy of lower limb non-unions. Utilization of the serum analysis of CCL-3 and IFN-γ 2 weeks after the treatment resulted in an early predictive value regarding the differentiation between patients that are likely to heal and those that are prone to high risk of treatment failure.

A Preliminary Study of Contrast-Enhanced Ultrasound (CEUS) and Cytokine Expression Analysis (CEA) as Early Predictors for the Outcome of Tibial Non-Union Therapy

The current study investigates if contrast-enhanced ultrasound (CEUS) or cytokine expression analysis (CEA) evaluating vascularization are capable of predicting the outcome of non-union therapy. Patients with tibial non-unions were surgically treated and participated in our follow-up program including perioperative collection of blood as well as CEUS analysis. Two groups were formed: Responders in group 1 (G1, N = 8) and Non-Responders in group 2 (G2, N = 5). Serum cytokine expression and local microperfusion were compared and correlated to the radiologic outcome. Evaluation of TNF-α expression revealed significantly lower values prior to first surgery in G1 (G1: 9.66 ± 0.96 pg/mL versus G2: 12.63 ± 1.2 pg/mL; p = 0.045); whereas after treatment both CEA and CEUS indicated a higher potential for angiogenesis in Responders. Logistic regression modelling revealed the highest predictive power regarding eventual osseous consolidation for the combination of both CEUS and serum CEA. The results provide first evidence regarding a link between changes in the serum expression of distinct pro-angiogenic cytokines and alterations in the local microperfusion assessed via both non-invasive and radiation-free diagnostic modalities. In addition, a combination of CEUS and CEA is a promising novel tool in early prediction of the outcome of non-union therapy.

Contrast-Enhanced Ultrasound Quantifies the Perfusion Within Tibial Non-Unions and Predicts the Outcome of Revision Surgery

Vascularity is one of the factors determining successful bone regeneration. This prospective study focused on quantifying the microperfusion of tibial non-unions with contrast-enhanced ultrasound (CEUS) 12 wk after revision surgery and comparing it with the osseous consolidation at a maximum of 24 mo assessed with standard radiography and computed tomography. Of 36 patients with tibial non-unions, 28 (77.8%) manifested consolidation, and 8 patients required further revision surgery. CEUS revealed significantly higher perfusion in consolidated versus persistent non-unions for all quantification parameters (e.g., wash-in perfusion index p = 0.036). Receiver operating characteristic analysis revealed a sensitivity of 82.1% and specificity of 75.0% with a wash-in perfusion index cutoff at 19.9 a.u. for diagnosing persisting non-unions. More than 1 y ahead of the final radiologic diagnostic examination, CEUS could predict eventual consolidation based on the osseous perfusion as soon as 12 wk postoperatively. This information can be crucial for the decision-making process for re-revision at an early stage.

Hybrid Fixation for Ankle Fusion in Diabetic Charcot Arthropathy

BACKGROUND

Ankle fusion is difficult to achieve in the diabetic Charcot ankle Brodsky type 3a because of the poor quality of the bone and the inability to achieve a stable biomechanical construct. The aim of this study was to report the outcome of ankle fusion using a combination of an intramedullary nail and a circular external fixator in patients with diabetic Charcot arthropathy.

METHODS

We prospectively studied 24 patients with diabetic Charcot arthropathy of the ankle who were treated by fusion of the tibiotalar joint using a combined retrograde intramedullary nail and Ilizarov external fixator. Their mean age was 50.7 ± 6.9 (range, 43-62) years. The mean follow-up after surgery was 36.4 ± 5.8 (range, 24-98) months.

RESULTS

Twenty-two patients (92%) achieved clinical and radiographic solid bony fusion. No patients in this series needed amputation. All the patients were pain free, and the mean American Orthopaedic Foot & Ankle Society Score (AOFAS) improved significantly from 34.6 ± 6.8 to 66.4 ± 4.5 at the last follow-up. Two patients developed an ulcer over the heel due to a prominent nail. The ulcer healed after nail removal. Eight patients developed pin tract infection.

CONCLUSION

We report a successful outcomes of ankle fusions using combined intramedullary nail locked only proximally and ring external fixator (hybrid fixation) in patients with diabetic Charcot arthropathy.

LEVEL OF EVIDENCE

Level IV, case series.

Negative magnetic resonance imaging in three cases of anterior tibial cortex stress fractures

Anterior mid-tibial cortex stress fractures (ATCSF) are uncommon and notoriously challenging to treat. They are termed high risk due to their predilection to prolonged recovery, nonunion and complete fracture. Early diagnosis is essential to avoid progression and reduce fracture complications. Imaging plays a key role in confirming the diagnosis. Magnetic resonance imaging (MRI) is accepted as the gold standard modality due to its high accuracy and nonionizing properties. This report describes three cases of ATCSFs in recreational athletes who had positive radiographic findings with no significant MRI changes. Two athletes had multiple striations within their tibias. Despite the radiographic findings, their severity of symptoms were low with mild or no tenderness on examination. Clinicians should be mindful that the ATCSFs may not present with typical acute stress fracture symptoms. We recommend that plain radiographs should be used as the first line investigation when suspecting ATCSFs. Clinicians should be aware that despite MRI being considered the gold standard imaging modality, we report three cases where the MRI was unremarkable, whilst radiographs and computed tomography confirmed the diagnosis. We urge clinicians to continue to use radiographs as the first line imaging modality for ATCSFs and not to directly rely on MRI. Those who opt directly for MRI may be falsely reassured causing a delay in diagnosis.

Image quality of cone beam computed tomography for evaluation of extremity fractures in the presence of metal hardware: visual grading characteristics analysis

OBJECTIVE

To evaluate image quality and interobserver reliability of a novel cone-beam CT (CBCT) scanner in comparison with plain radiography for assessment of fracture healing in the presence of metal hardware.

METHODS

In this prospective institutional review board-approved Health Insurance Portability and Accountability Act of 1996-complaint study, written informed consent was obtained from 27 patients (10 females and 17 males; mean age 44 years, age range 21-83 years) with either upper or lower extremity fractures, and with metal hardware, who underwent CBCT scans and had a clinical radiograph of the affected part. Images were assessed by two independent observers for quality and interobserver reliability for seven visualization tasks. Visual grading characteristic (VGC) curve analysis determined the differences in image quality between CBCT and plain radiography. Interobserver agreement was calculated using Pearson's correlation coefficient.

RESULTS

VGC results displayed preference of CBCT images to plain radiographs in terms of visualizing (1) cortical and (2) trabecular bones; (3) fracture line; (4) callus formation; (5) bridging ossification; and (6) screw thread-bone interface and its inferiority to plain radiograph in the visualization of (7) large metallic side plate contour with strong interobserver correlation (p-value < 0.05), except for visualizing large metallic side plate contour.

CONCLUSION

For evaluation of fracture healing in the presence of metal hardware, CBCT image quality is preferable to plain radiograph for all visualization tasks, except for large metallic side plate contours. Advances in knowledge: CBCT has the potential to be a good diagnostic alternative to plain radiographs in evaluation of fracture healing in the presence of metal hardware.

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) for the prediction of non-union consolidation

INTRODUCTION

Non-union perfusion can be visualized with dynamic contrast-enhanced (DCE) MRI. This study evaluated DCE-MRI to predict non-union consolidation after surgery and detect factors that affect bone healing.

MATERIALS AND METHODS

Between 2010 and 2015 non-union perfusion was prospectively quantified in 205 patients (mean age, 51.5 years, 129 men, 76 women) before intervention and at 6, 12, 26, 52 and more weeks follow-up. DCE-MRI results were related to the osseous consolidation, the ability to predict successful outcome was estimated by ROC analysis. The relevance of the body mass index (BMI) and the non-union severity score (NUSS) to the healing process was assessed.

RESULTS

Tibial (n=99) and femoral (n=76) non-unions were most common. Consolidation could be assessed in 169 patients, of these 103 (61%) showed eventual healing and demonstrated higher perfusion than in failed consolidation at 6 (p=0.0226), 12 (p=0.0252) and 26 (p=0.0088) weeks follow-up. DCE-MRI at 26 weeks follow-up predicted non-union consolidation with a sensitivity of 75% and a specificity of 87% (false classification rate 19%). Higher BMI (p=0.041) and NUSS (p<0.0001) were associated with treatment failure.

CONCLUSIONS

DCE-MRI perfusion analysis after non-union surgery predicts successful outcome and could facilitate the decision of early intervention. NUSS and BMI are important prognostic factors concerning consolidation.

Nonunion of the Femur and Tibia: An Update

Delayed union and nonunion of tibial and femoral shaft fractures are common orthopedic problems. Numerous publications address lower extremity long bone nonunions. This review presents current trends and recent literature on the evaluation and treatment of nonunions of the tibia and femur. New studies focused on tibial nonunion and femoral nonunion are reviewed. A section summarizing recent treatment of atypical femoral fractures associated with bisphosphonate therapy is also included.

Reproducibility of computed tomography to evaluate ankle and hindfoot fusions

BACKGROUND

Although plain radiographs have been historically used to evaluate the status of arthrodesis in the foot and ankle, computed tomography (CT) has gained popularity for evaluation of fusion status. The degree of fusion identified on CT scan has been correlated with functional outcome, with an arthrodesis area of 25-50% necessary for clinical success. In the clinical setting, orthopaedic surgeons often evaluate CT scans independently. The purpose of this study was to evaluate the interrater reliability of CT scans to assess the status of hindfoot or ankle fusions among orthopaedic foot and ankle surgeons.

METHODS

Forty-one CT scans were identified retrospectively from the tertiary referral practices of 4 fellowship-trained orthopaedic foot and ankle surgeons. Inclusion criteria were patients with ankle, subtalar, or tibiotalocalcaneal fusions. Fusions with bulk allograft were excluded. All CT scans were completed at the investigating institution. The primary author (RAC) reviewed all CT scans to ensure the adequacy and completeness of the films. Images were blinded of any patient identifiers. All 4 surgeons individually reviewed the blinded scans and determined whether the arthrodesis site was greater than or less than 50% fused. Interrater reliability was completed via kappa analysis.

RESULTS

Based on kappa analysis, there was high interrater reliability in the assessment of subtalar arthrodesis. This was not statistically significant for the evaluation of ankle arthrodesis.

CONCLUSION

The CT scan has become instrumental in determining the adequacy of arthrodesis in the foot and ankle. The present study demonstrates the reliability of orthopaedic surgeons to ascertain the status of subtalar arthrodesis via CT scan.

LEVEL OF EVIDENCE

Level IV, case series.

Imaging techniques for the assessment of fracture repair

Imaging of a healing fracture provides a non-invasive and often instructive reproduction of the fracture repair progress and the healing status of bone. However, the interpretation of this reproduction is often qualitative and provides only an indirect and surrogate measure of the mechanical stability of the healing fracture. Refinements of the available imaging techniques have been suggested to more accurately determine the healing status of bone. Plain radiographs provide the ability to determine the degree of bridging of the fracture gap and to quantify the amount of periosteal callus formation. Absorptiometric measures including dual X-ray absorptiometry and computed tomography provide quantitative information on the amount and the density of newly formed bone around the site of the fracture. To include the effect of spatial distribution of newly formed bone, finite element models of healing fracture can be employed to estimate its load bearing capacity. Ultrasound technology not only avoids radiation doses to the patients but also provides the ability to additionally measure vascularity in the surrounding soft tissue of the fracture and in the fracture itself.

Recent advances in the use of serological bone formation markers to monitor callus development and fracture healing

The failure of an osseous fracture to heal, or the development of a nonunion, is common; however, current diagnostic measures lack the capability of early and reliable detection of such events. Analyses of radiographic imaging and clinical examination, in combination, remain the gold standard for diagnosis; however, these methods are not reliable for early detection. Delayed diagnosis of a nonunion is costly from both the patient and treatment standpoints. In response, repeated efforts have been made to identify bone metabolic markers as diagnostic or prognostic tools for monitoring bone healing. Thus far, the evidence regarding a correlation between the kinetics of most bone metabolic markers and nonunion is very limited. With the aim of classifying the role of biological pathways of bone metabolism and of understanding bone conditions in the development of osteoporosis, advances have been made in our knowledge of the molecular basis of bone remodeling, fracture healing, and its failure. Procollagen type I amino-terminal propeptide has been shown to be a reliable bone formation marker in osteoporosis therapy and its kinetics during fracture healing has been recently described. In this article, we suggest that procollagen type I amino-terminal propeptide presents a good opportunity for early detection of nonunion. We also review the role and potential of serum PINP, as well as other markers, as indications of fracture healing.

Correlation of arthrodesis stability with degree of joint fusion on MDCT

OBJECTIVE

The purpose of our study was to correlate clinically determined joint stability with the degree of bone fusion in the ankle or subtalar joint on MDCT examinations after arthrodesis.

MATERIALS AND METHODS

We performed a retrospective review of 42 consecutive MDCT examinations from 29 patients. All patients had previously undergone arthrodesis of their ankle or subtalar joints and had persistent or recurrent hindfoot or ankle pain. Two musculoskeletal radiologists examined in consensus sagittal 2-mm-thick reformatted slices, measuring on each image the length of the joint surface and the length of the fused portion of the joint space. The sum of the lengths of the fused segments on all slices was then divided by the sum of the lengths of the joint surfaces to calculate the fusion ratio. For the standard of reference, the medical records were reviewed and operative reports, diagnostic injections, and physical examinations were used to classify the joints as stable or unstable.

RESULTS

Twelve clinically unstable joints had fusion ratios of 0-32.8%, whereas 30 clinically stable joints had fusion ratios of 33.2-100%. Using receiver operating characteristic analysis, we selected the cutoff level that maximized Youden's index (the sum of sensitivity and specificity). Using a 33% fusion ratio as the lower limit cutoff for joint stability, the sensitivity was 100%; specificity, 100%; and accuracy, 100%.

CONCLUSION

After arthrodesis of the ankle or subtalar joint, MDCT scans can be used to determine whether that joint is likely to be stable if > 33% of the joint has visible bone fusion on sagittal MDCT images.

Micro-computed tomography assessment of fracture healing: relationships among callus structure, composition, and mechanical function

Non-invasive characterization of fracture callus structure and composition may facilitate development of surrogate measures of the regain of mechanical function. As such, quantitative computed tomography- (CT-) based analyses of fracture calluses could enable more reliable clinical assessments of bone healing. Although previous studies have used CT to quantify and predict fracture healing, it is unclear which of the many CT-derived metrics of callus structure and composition are the most predictive of callus mechanical properties. The goal of this study was to identify the changes in fracture callus structure and composition that occur over time and that are most closely related to the regain of mechanical function. Micro-computed tomography (microCT) imaging and torsion testing were performed on murine fracture calluses (n=188) at multiple post-fracture timepoints and under different experimental conditions that alter fracture healing. Total callus volume (TV), mineralized callus volume (BV), callus mineralized volume fraction (BV/TV), bone mineral content (BMC), tissue mineral density (TMD), standard deviation of mineral density (sigma(TMD)), effective polar moment of inertia (J(eff)), torsional strength, and torsional rigidity were quantified. Multivariate statistical analyses, including multivariate analysis of variance, principal components analysis, and stepwise regression were used to identify differences in callus structure and composition among experimental groups and to determine which of the microCT outcome measures were the strongest predictors of mechanical properties. Although calluses varied greatly in the absolute and relative amounts of mineralized tissue (BV, BMC, and BV/TV), differences among timepoints were most strongly associated with changes in tissue mineral density. Torsional strength and rigidity were dependent on mineral density as well as the amount of mineralized tissue: TMD, BV, and sigma(TMD) explained 62% of the variation in torsional strength (p<0.001); and TMD, BMC, BV/TV, and sigma(TMD) explained 70% of the variation in torsional rigidity (p<0.001). These results indicate that fracture callus mechanical properties can be predicted by several microCT-derived measures of callus structure and composition. These findings form the basis for developing non-invasive assessments of fracture healing and for identifying biological and biomechanical mechanisms that lead to impaired or enhanced healing.

Computed tomography reformation in evaluation of fracture healing with metallic fixation: correlation with clinical outcome

BACKGROUND

The amount of callous needed for fracture stability is typically estimated by a combination of radiographic and physical examinations. Computed tomography (CT) with sagittal and coronal reformations was performed to determine the amount of callous needed for fracture stability based on a quartile analysis of bony bridging of the circumference of the fracture site.

METHODS

All patients who received CT with sagittal and coronal reformations of a fractured tubular bone for the purpose of analyzing bony bridging over a 22-month period were retrospectively reviewed. The final analysis included 34 patients and a total of 47 examinations. Fractures were placed into one of four groups depending on the amount of cortical bridging of the circumference of the bone: group I, 0-24%, group II, 25-49%, group III, 50-74%, group IV, 75-100%. Clinical outcome was determined on the basis of fracture stability, with mean follow-up of approximately 62 weeks.

RESULTS

A statistically significant increase in clinical failure was found in patients with <25% bridging. A cut-point analysis revealed that 37.5% (6 of 16) of failures occurred among patients with <25% bony bridging, and only 9.7% (3 of 31) of failures occurred among patients with >25% bridging, corresponding to a Fisher's exact test p value of 0.045.

CONCLUSIONS

Patients with less than 25% bridging of the circumference of a tubular bone should be considered high risk for failure, indicating the need for continued protection of the site.

Distinguishing Jones and proximal diaphyseal fractures of the fifth metatarsal

Jones and proximal diaphyseal fractures of the fifth metatarsal are in close anatomic proximity and often are difficult to differentiate. We determined whether it is necessary to differentiate between these two diagnoses. Retrospectively, the two diagnoses were identified radiographically using an accepted classification scheme. Initial management is nonoperative; however, intramedullary screw fixation is performed for competitive athletes, or others with displaced fractures, or delayed union or nonunion. Outcomes were analyzed using Student's t tests, whereas nominal data were analyzed using chi square tests. Thirty-two Jones fractures and 29 proximal diaphyseal fractures were identified. All fractures healed between 4.8 and 9.8 months with a 78% to 82% patient satisfaction rate. Regardless of treatment, the clinical outcomes were not different between the two fracture locations. Shorter return to sport time was observed in operatively treated patients. Operatively treated patients with fracture site sclerosis or medullary canal obliteration on radiographs had lower satisfaction and higher complication rates than patients without these changes. Based on our findings, we do not find a reason to distinguish between fractures of the fifth metatarsal in these two locations. We suggest referring to fifth metatarsal base fractures (excluding avulsions) as Jones fractures.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

The use of 18F-fluoride and 18F-FDG PET scans to assess fracture healing in a rat femur model

PURPOSE

Currently available diagnostic techniques can be unreliable in the diagnosis of delayed fracture healing in certain clinical situations, which can lead to increased complication rates and costs to the health care system. This study sought to determine the utility of positron emission tomography (PET) scanning with (18)F-fluoride ion, which localizes in regions of high osteoblastic activity, and (18)F-fluorodeoxyglucose (FDG), an indicator of cellular glucose metabolism, in assessing bone healing in a rat femur fracture model.

METHODS

Fractures were created in the femurs of immunocompetent rats. Animals in group I had a fracture produced via a manual three-point bending technique. Group II animals underwent a femoral osteotomy with placement of a 2-mm silastic spacer at the fracture site. Fracture healing was assessed with plain radiographs, (18)F-fluoride, and (18)F-FDG PET scans at 1, 2, 3, and 4-week time points after surgery. Femoral specimens were harvested for histologic analysis and manual testing of torsional and bending strength 4 weeks after surgery.

RESULTS

All fractures in group I revealed abundant callus formation and bone healing, while none of the nonunion femurs were healed via assessment with manual palpation, radiographic, and histologic evaluation at the 4-week time point. (18)F-fluoride PET images of group I femurs at successive 1-week intervals revealed progressively increased signal uptake at the union site during fracture repair. In contrast, minimal tracer uptake was seen at the fracture sites in group II at all time points after surgery. Data analysis revealed statistically significant differences in mean signal intensity between groups I and II at each weekly interval. No significant differences between the two groups were seen using (18)F-FDG PET imaging at any time point.

CONCLUSION

This study suggests that (18)F-fluoride PET imaging, which is an indicator of osteoblastic activity in vivo, can identify fracture nonunions at an early time point and may have a role in the assessment of longitudinal fracture healing. PET scans using (18)F-FDG were not helpful in differentiating metabolic activity between successful and delayed bone healing.

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.

Percutaneous bone marrow grafting for the treatment of tibial non-union

This is a prospective study to evaluate the efficacy of percutanous bone marrow grafting in patients with established tibial non-union and minimal deformity, whilst on the waiting list for open surgical procedures. Twenty consecutive patients with established tibial non-union and minimal deformity were treated by percutanous bone marrow injection under local anaesthesia. Bone marrow was obtained from the iliac crest, 3-5 ml of marrow was aspirated and injected immediately into and about the non-union site. Subsequent aspirations were performed 1 cm posterior to the previous site until a maximum of 15 ml of marrow was injected. Our results revealed clinical and radiological bone union following percutanous injection in 15 out of 20 patients (75%), with an average time to union following the first injection of 14 weeks. Four patients (20%) showed no evidence of union and were considered a failure. There were no cases of infection following the injection, and no complications at the donor site. We conclude that percutanous bone marrow grafting is a safe, simple, and reliable method of treating tibial non-union with minimal deformity. It is a limited invasive technique with minimal complications. It can be performed under local anaesthesia, is cost effective and potentially can avoid major surgical reconstruction.

Comparison of Accuracy of Three-Dimensional Spiral Computed Tomography, Standard Radiography, and Direct Measurements in Evaluating Facial Fracture Healing in a Rat Model

Complex maxillofacial fractures demand a detailed understanding of the three-dimensional (3D) pattern of injury. Evaluation of the outcome of the facial fracture repair additionally requires optimal demonstration of fracture gap, bony union, fibrous callus or incorporation of fracture ends, presence of incomplete fusion, or pseudoarthrosis. Although 3D computed tomography (CT) is reliably used for the diagnosis of complex facial fractures, its value in facial fracture healing is unknown. An experimental study was conducted to determine the accuracy of 3D spiral CT scans in evaluating facial fracture healing during the early and late postoperative periods. In 10 adult Wistar Albino rats, a standardized bone defect (3 mm) was created within the mid portion of each zygomatic arch (n = 20). At 10 and 20 weeks postfracture, gap distance displayed by 3D CT and plane radiography (posteroanterior) were measured. At 20 weeks postfracture, intraoperative measurement was also performed. A comparison between 3D CT, radiography, and intraoperative findings was performed. At 10 weeks postfracture, the fracture sites displayed larger bone defects in imaging with 3D CT than with plane radiography. The difference between groups was statistically significant (P < 0.05). The mean defect size imaged by 3D CT was 0.91 +/- 0.82 mm (standard deviation) and by plane radiography was 0.42 +/- 0.16 mm. At 20 weeks postfracture, the mean defect size imaged by 3D CT was 0.56 +/- 0.64 mm, and by plane radiography was 0.38 +/- 0.22 mm. The difference between groups was not statistically significant (P > 0.05). The defect size imaged by both plane radiography and 3D CT was significantly less than the measurement obtained from the intraoperative assessment (P < 0.05). It was concluded that 3D CT has limited benefit in the detection of newly formed bone at week 10 and in the detection of fibrous callus, which can eventually give rise to the bony tissue. Plane radiography is more valid during the early postoperative period (week 10), because it can detect the fibrous callus and newly formed bone more precisely. Gap distance between fracture ends could be determined by 3D CT accurately at week 20, although there was a tendency, which was not statistically significant, to overestimate the amount of bone defect measured by 3D CT when compared with that of plane radiography.

The vacuum phenomenon: a CT sign of nonunited fracture

OBJECTIVE

The purpose of this study was to describe on CT scans the presence of a gas collection within a bone fracture reflecting the vacuum phenomenon as a sign of nonunited fracture.

CONCLUSION

A gas collection between fractured bone fragments suggests a nonunited fracture.

Assessment of femoral neck nonunion with multiplanar computed tomography reconstruction

Femoral neck fracture nonunion after implant fixation is usually evaluated by physical findings and serial radiography. Radiography in hip fixation is complicated by inherent anatomy and the geometry of screw placement. Computed tomography with multiplanar reconstruction offers adjunct evaluation using nonstandard imaging planes tailored to favor fracture plane projection and individual screw evaluation. Metal artifacts can be minimized and lack of fracture bridging can be excluded with confidence. Experience with seven cases of femoral neck fracture nonunion is presented along with image examples.

Stimulation of bone healing in new fractures of the tibial shaft using interferential currents

The aim of this research was to establish whether interferential currents (IFC) could significantly reduce the healing time for fractures of the tibia and thereby prevent nonunion. Males between the ages of 12 and 86, who had sustained fractures of the tibiae, were entered into this double blind clinical trial. According to strict inclusion and exclusion criteria, a final sample of 227 cases (208 subjects) were entered by block randomization into two groups; an experimental group (n = 41) and placebo group (n = 35). A further group was entered retrospectively--control group (n = 151). IFCs were applied to the experimental group via suction electrodes for 30 minutes per day for 10 days, using a beat frequency of 10-25 Hz and a swing mode of 6 integral of 6. The placebo group had only suction electrodes applied, the intermittent mode produced a rhythmical massage effect; subjects in this group commented on pain relief which resulted in the addition of the control group as a check on the possible effect of intermittent suction. The control group received no intervention. The data were analysed using analysis of covariance which resulted in a finding of no significant difference in the time taken to union for the three groups. This means that to date there is no reason to believe that IFCs (using the parameters of this trial) can reduce the healing time for new fractures of the tibia or prevent nonunion. However, further investigation is recommended.