Sonographic bridging callus: An early predictor of fracture union

Utility of ultrasound imaging in monitoring fracture healing in rat femur: Comparison with other imaging modalities

Objective

Fractures are common injuries and various imaging modalities are employed to diagnose and monitor bone union. However, the follow-up of fracture healing using ultrasound imaging (US) remains a topic of debate. In this study, we analyzed of fracture healing process and compared US and radiological analyses with histological analyses to clarify the characteristics and limitations of each modality.

Methods

An osteotomy model was created using the femur of Wistar rats, and US, radiological (radiography and micro-computed tomography (micro-CT)), and histological analyses were performed. Radiological assessments were conducted for the evaluation of calcified tissue. The gap between the bony callus and cartilaginous callus was measured.

Results

US effectively captured changes on the fracture surface, potentially reflecting the early healing processes. Both US and radiographic findings showed strong correlation in terms of the decrease in the bony callus gap. US was unable to distinguish cartilaginous callus from the surrounding soft tissue. During the remodeling stage, micro-CT offered a detailed assessment of the internal fracture surface, whereas US was limited to evaluating the outer bone surface and lacked accuracy in visualizing the entire fracture site. Radiography provided a general overview of the fractures. The decrease in the bony callus gap measured using US correlated with the reduction in cartilaginous callus observed histologically.

Conclusion

This study demonstrated that US could be a valuable tool for evaluating fracture healing. Combining fracture management with US and radiological examinations may provide a more accurate assessment of healing progress.

Minimal early functional gains after operative treatment of midshaft clavicular fractures: a meta-analysis of 10 randomized controlled trials including 1333 patients

Background

There is substantial evidence that operative treatment reduces the risk of nonunion but offers no long-term functional gains compared with nonoperative treatment. Despite some studies citing quicker recovery with surgery, the promise of accelerated functional recovery remains under-investigated. The aim of this meta-analysis of randomized controlled trials was to investigate the possible early functional gains (≤6 months) after operative treatment of displaced midshaft clavicular fractures compared with nonsurgical treatment.

Methods

A systematic search was performed to identify randomized controlled trials comparing plate osteosynthesis with nonoperative treatment. We evaluated shoulder function outcomes measured by Constant Score or Disability of the Arm, Shoulder, and Hand (DASH) questionnaire. Other outcomes of interest were sick leave and return to previous activity (work, leisure).

Results

Ten studies including 1333 patients were included. The mean difference in DASH score after 6 weeks was 9.4 points (95% confidence interval [CI] 13.7-5.1) in favor of operative treatment. At 3 months, the difference was 3.6 points (95% CI 6.9-0.4), and at 6 months, the difference was 3.2 points (95% CI 5.2-1.1), both in favor of operative treatment. Results for Constant Score were similar to that of DASH score.

Conclusion

This meta-analysis shows that there is an early functional gain at six weeks following plate fixation of midshaft clavicular fractures compared with nonoperative treatment. At three and six months, the functional gain is lesser and not clinically relevant.

Approach to Tibial Shaft Nonunions: Diagnosis and Management

The tibia is the most common long bone at risk for nonunion with an annual incidence ranging from 12% to 19%. This topic continues to be an area of research as management techniques constantly evolve. A foundational knowledge of the fundamental concepts, etiology, and risk factors for nonunions is crucial for success. Treatment of tibial shaft nonunions often requires a multidisciplinary effort. This article provides guidance based on the most recent literature that can be used to aid the treating provider in the diagnosis, workup, and management of tibial shaft nonunions.

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.

Principles and Evaluation of Bony Unions

Nonunion is a common and costly problem. Unfortunately, there is no widely agreed upon and standardized definition for nonunion. The evaluation of bony union should start with a thorough history and physical examination. The clinician should consider patient-dependent as well as patient-independent characteristics that may influence the rate of healing and evaluate the patient for physical examination findings suggestive of bony union and infection. Radiographs and clinical examination can help confirm a diagnosis of union. When the diagnosis is in doubt, however, advanced imaging modalities as well as laboratory studies can help a surgeon determine when further intervention is necessary.

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

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

Point-of-care ultrasound in musculoskeletal field

The musculoskeletal field is relatively new in point-of-care ultrasound (POCUS), a modality that has been gaining significance with the evolution of ultrasound (US) equipment and high-frequency probes. Images have become progressively clearer over the past decade, making it possible to diagnose many pathological conditions without exposure to radiation. Ultrasonography reveals many soft tissue pathologies that cannot be visualized using plain radiographs, which have historically been the first choice for the evaluation of musculoskeletal disorders. US saves money and time compared to magnetic resonance imaging (MRI). Although it is difficult to diagnose a disorder inside bone, its surface can be visualized very clearly, and it is also possible to visualize cartilage. Furthermore, with POCUS, it is possible to confirm a disorder and the continuity of the fibrous structures of muscles, tendons, and ligaments. In addition, the understanding of pathological conditions of motor disturbances, such as nerve or muscle/tendon injury, nerve paralysis, adhesions of the tendons, and joint instability, is deepened by observing the movement of these structures. Peripheral nerves, even small branches, can be visualized, and pathological conditions can be pinpointed by observing the nerve morphology, continuity, and relationship with the surrounding tissues. Children can be examined in a safe, relaxed environment, without leaving their parents. In addition, US is significantly different from other modalities in that it can be used for both diagnosis and treatment. Being able to visualize target sites improves safety and route accuracy of needle insertion for injection or puncture. Musculoskeletal POCUS is indispensable in routine medical care and is a technique that medical residents should acquire.

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.

Contrast-Enhanced Ultrasound: A Viable Diagnostic Tool in Predicting Treatment Failure after Non-union Revision Surgery for Upper- and Lower-Limb Non-unions

Non-unions remain a major complication in the treatment of long-bone fractures and affect quality of life considerably. Both early detection and treatment of non-unions are essential to secure subsequent fracture union. Sufficient vascularization plays a key role in the healing process. The aim of this prospective study was to quantify the microperfusion within non-unions by means of contrast-enhanced ultrasound (CEUS) as early as 12 wk after non-union surgery and to examine the prognostic capability of CEUS in predicting treatment failure. Among 112 patients who had undergone non-union surgery, consolidation within 36 mo was achieved in 89 patients ("responders"), whereas 23 patients showed persistent non-unions ("non-responders") and required further surgery. CEUS quantification parameters such as peak enhancement, wash-in area under the curve and wash-in perfusion index revealed significantly higher perfusion levels in "responders" compared with "non-responders" (p < 0.05). Receiver operator characteristic curve analysis revealed that persistent fracture non-unions could be predicted with a sensitivity/specificity of 88.7%/72.2% in lower-limb non-unions and a sensitivity/specificity of 66.7%/100.0% in upper-limb non-unions. CEUS is a suitable diagnostic tool in predicting treatment failure as early as 12 wk after non-union surgery and should be integrated into the clinical routine when deciding on revision surgery at an early stage.

Ultrasound Frequency-Based Monitoring for Bone Healing

Correct assessment of the bone healing process is required for the management of limb immobilization during the treatment of bone injuries, including fractures and defects. Although the monitoring of bone healing using ultrasound poses several advantages regarding cost and ionizing radiation exposure compared with other dominant imaging methods, such as radiography and computed tomography (CT), traditional ultrasound B-mode imaging lacks reliability and objectivity. However, the body structures can be quantitatively observed by ultrasound frequency-based methods, and therefore, the disadvantages of B-mode imaging can be overcome. In this study, we created a femoral bone hole model of a rat and observed the bone healing process using the quantitative ultrasound method and micro-CT, which provides a reliable assessment of the tissue microstructure of the bone. This study analyzed the correlation between these two assessments. The results revealed that the quantitative ultrasound measurements correlated with the CT measurements for rat bone healing. This ultrasound frequency-based method could have the potential to serve as a novel modality for quantitative monitoring of bone healing with the advantages of being less invasive and easily accessible. Impact statement Bone healing monitoring with ultrasound is advantageous as it is less invasive and easily accessible; however, the traditional B-mode method lacks reliability and objectivity. This study demonstrated that the proposed ultrasound frequency-based monitoring method can quantitatively observe bone healing and strongly correlates with the computed tomography measurements for rat bone healing. This method has the potential to become a reliable modality for monitoring bone healing.

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.

Minimal Pain Decrease Between 2 and 4 Weeks After Nonoperative Management of a Displaced Midshaft Clavicle Fracture Is Associated with a High Risk of Symptomatic Nonunion

BACKGROUND

The main long-term benefit of operative treatment of displaced midshaft clavicular fractures is the reduction in nonunion risk, and as this risk is generally low, the ideal approach would be to operate only patients at high risk of nonunion. However, most current surgical decision models use baseline variables to estimate the nonunion risk, and the value of these models remains unclear. Pain in the early weeks after fracture could be potentially be an indirect measurement of fracture healing, and so it is a potential proxy variable that could lead to simpler prediction models.

QUESTIONS/PURPOSES

(1) Is pain a possible proxy variable for the development of symptomatic nonunion after nonoperative treatment of midshaft clavicular fractures? (2) How reliable is the model we created that uses pain as a proxy variable for symptomatic nonunion of nonoperatively treated clavicle fractures?

METHODS

In this secondary retrospective analysis of an earlier randomized trial, we studied prospectively collected data from 64 nonoperatively treated patients aged 18 years to 60 years. In the original randomized trial, we compared operative and nonoperative treatment of displaced midshaft clavicular fractures. In all, 150 patients were included in the study, of whom 71 received nonoperative treatment. Patients were predominantly males (75%, 48 of 64) with a mean age of 38 ± SD 12 years; most fractures were comminuted and shortened more than 1 cm. All 71 patients who were nonoperatively treated were potentially eligible for this secondary analysis; of those, 11% (8 of 71) were lost to follow-up, leaving 63 patients from the nonoperative treatment arm and one patient from the operative treatment arm (who declined surgical treatment after randomization but was followed in this group according to the intention-to-treat principle) for analysis here. Nonunion was defined as lack of callus formation, persistent fracture lines and/or sclerotic edges of the bones at the fracture site on plain radiographs at 6 months follow-up. Nonunions were regarded as symptomatic if pain, tenderness, and local crepitation were present at the fracture site. Seventeen percent (11 of 64) of patients had symptomatic nonunions. After investigating differences in early pain scores between the union and nonunion groups, we defined the VASratio as the VAS pain score at 4 weeks divided by the VAS pain score at 2 weeks. Week 2 VAS pain score was chosen as baseline after visual inspection of a linear mixed model that showed increased divergence in pain scores between union and nonunion group at 2 weeks after fracture. Week 4 was chosen as the cutoff because we wanted a reasonable time frame for the detection of pain reduction and did not want to delay surgical treatment more than necessary. Odds ratios for various risk factors were calculated using logistic regression analyses. We used a receiver operating characteristic curve analysis to identify cutoff values for the VASratio.

RESULTS

An increase in absolute pain score at 4 weeks after fracture (odds ratio 1.8 per 1 point increase [95% confidence interval 1.1 to 3.4]) was associated with an increased risk of nonunion 6 months after fracture. Likewise, we found that an increasing VASratio (OR 1.02 per 0.01 point increase [95% CI 1.002 to 1.06]) was also associated with nonunion. Receiver operating curve analysis found that the best cutoff value of VASratio was about 0.6. Patients with a VASratio above 0.6 had a relative risk of developing nonunion of 18 (95% CI 2 to 130) compared with patients with a VASratio below 0.6. Sparse-data bias could be present, as is evident from this wide confidence interval, though even at the low end of the confidence interval, the relative risk was 2, which may still improve surgical decision-making.

CONCLUSION

A pain score that exhibits no or minimal change from 2 to 4 weeks after nonoperative treatment of a displaced midshaft fracture of the clavicle is associated with a high risk that symptomatic nonunion will develop. Patients with no or minimal change in pain in the early weeks may be candidates for surgery to reduce the risk of symptomatic nonunion. As this was a retrospective study, with a risk of sparse-data bias, the predictive value of the VASratio needs to be further investigated in large prospective studies before clinical use.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Epidemiology, Clinical Assessments, and Current Treatments of Nonunions

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

Imaging Modalities to Assess Fracture Healing

PURPOSE OF REVIEW

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

RECENT FINDINGS

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