Validity of Indirect Ultrasound Findings in Acute Anterior Cruciate Ligament Ruptures

Prone Lachman with Ultrasound: A Literature Review and Description of the Technique

ABSTRACT

Magnetic resonance imaging is the current gold standard imaging modality for diagnosing anterior cruciate ligament (ACL) tears. However, ultrasound has grown in popularity for detecting ACL injuries because of its low cost, portability, and dynamic assessment capabilities. Recent studies demonstrate high sensitivity and specificity for diagnosing isolated ACL tears via ultrasound, but tremendous heterogeneity remains for optimal technique including patient positioning, transducer placement, and dynamic versus static ultrasound usage. As ultrasound becomes ubiquitous in clinics, training rooms, and on the sidelines, identifying objective and sensitive measurements to appropriately screen athletes for significant knee injuries is imperative. This article aims to review the current role of diagnostic ultrasound in ACL injuries and propose a standardized version of the Prone Lachman with Ultrasound test, which is an objective, reliable, and easily reproducible technique to evaluate ACL competency. Developing a standardized protocol will expand the use of point-of-care ultrasound, which may reduce cost and improve efficiency in care.

Ultrasound Imaging of the Anterior Cruciate Ligament: A Pictorial Essay and Narrative Review

Ultrasound has been extensively applied to the diagnosis of and guided interventions for knee disorders. However, although it is commonly affected during sports injuries, the anterior cruciate ligament (ACL) is not usually incorporated in the majority of ultrasound scanning protocols. In the past, because of its oblique trajectory and deeper location, the ACL was considered to be a challenging structure for ultrasound imaging. Owing to advances in ultrasound technology and knowledge of knee sono-anatomy, an increasing number of studies are investigating the clinical value of ultrasound in the diagnosis and management of ACL injuries. In this regard, the present review aims to elaborate on the sono-anatomy of the ACL, to summarize the evidence for ultrasound imaging for ACL lesions and to investigate whether it is useful in the pre-operative preparation and post-operative follow-up of ACL reconstruction.

Superb microvascular imaging (SMI) detects increased vascularity of the torn anterior cruciate ligament

PURPOSE

Ultrasound with superb microvascular imaging (SMI) is a novel microvascular imaging technology which may be useful to assess the vascularity of the torn anterior cruciate ligament (ACL) as a potential measure of healing potential following surgery. This study aimed to quantify the vascularity of the torn and intact ACL using ultrasound with SMI.

METHODS

23 patients (mean age ± standard deviation, 27.1 ± 12.8 years), who were diagnosed with an ACL tear with an intact contralateral ACL were enrolled (ACL injury group). Ten healthy volunteers (36.1 ± 4.9 years) who had intact ACLs in both knees were also recruited (ACL healthy controls). The vascularity of the ACL was assessed using SMI within 15 mm from the tibial insertion in both knees. The amount of the vascular signal was assessed using a semi-quantitative grading scale (vascularity grade: grade 0-3) and a quantified ratio of vascularized area with respect to total area of the region of interest (vascularity ratio).

RESULTS

In the ACL injury group, a significantly higher vascularity grade and ratio were observed in the torn ACL (vascularity grade 0-3: 1, 8, 7, and 7 patients, respectively; vascularity ratio: 1.3 ± 1.4%) than the contralateral intact ACL (vascularity grade 0-3: 21, 1, 1, and 0 patients, respectively; vascularity ratio: 0.1 ± 0.5%) (P < 0.001), whereas no significant difference was observed between both ACLs in the ACL healthy control group.

CONCLUSIONS

SMI was useful to assess the increased vascularity in torn ACL, which may reflect the potential for, or state of, ACL maturation following reconstruction or repair.

LEVEL OF EVIDENCE

Level III.

Diagnostic Musculoskeletal Ultrasound for the Acute Evaluation and Management of Soccer Players

ABSTRACT

Musculoskeletal ultrasound (US) has many applications in the care of athletes. This article reviews the current literature and identifies research gaps regarding musculoskeletal US in the athletic training room setting to evaluate and manage soccer players. The best evidence for US in the training room setting is for diagnosis and prognosis of muscle injuries, where studies show that it is equivalent to other imaging modalities. US also has been used for injury risk prediction, although the data are mixed. Many applications of US are described in other sport settings and may have crossover applications to soccer.

Diagnostic accuracy of dynamic ultrasound imaging in partial and complete anterior cruciate ligament tears: a retrospective study in 247 patients

Objectives

Dynamic ultrasound (US) imaging shows promising possibilities for accurate imaging in diagnosing anterior cruciate ligament (ACL) tears and can be used as a point-of-care test. The aim of this study is to determine the diagnostic accuracy of dynamic US imaging for detecting partial and complete ACL tears.

Methods

247 patients presenting with knee complaints, who underwent dynamic US imaging as well as arthroscopy for any intra-articular knee pathology, were retrospectively evaluated. We differentiated between partial and complete ACL tears.

Results

Dynamic US imaging revealed 95 of 108 arthroscopically confirmed ACL tears (sensitivity 88%, specificity 82%, positive predictive value (PPV) 79%, negative predictive value (NPV) 90%, and diagnostic OR (DOR) of 33.3). Sensitivity of US in the detection of partial ACL tears was 52%, specificity 85%, PPV 52%, NPV 84% and DOR 5.8. Complete ACL tears were depicted with a sensitivity of 79%, specificity of 89%, PPV of 63%, NPV of 95% and DOR 29.8. Multivariate regression analysis adjusting for age (dichotomised per 5 years) and previous knee surgery showed similar DOR.

Conclusion

The excellent NPV for complete ACL tears indicates that dynamic US imaging can be used as an initial imaging point-of-care test. However, the clinical presentation should be taken into account, especially in case of subtotal tears. Whereas it seems relatively easy to differentiate between (small) partial ACL tears, complete ACL tears and no tears, it seems to be difficult to differentiate subtotal tears from complete tears.

Efficiency of knee ultrasound for diagnosing anterior cruciate ligament and posterior cruciate ligament injuries: a systematic review and meta-analysis

OBJECTIVE

To evaluate the diagnostic performance of knee ultrasound for anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) injuries.

MATERIALS AND METHODS

PubMed and EMBASE databases were searched for diagnostic accuracy studies that used ultrasound for diagnosing ACL and PCL injuries. Bivariate and hierarchical summary receiver operating characteristic modeling was used to evaluate diagnostic performance. Subgroup analysis was performed by assessing studies conducted using the ultrasound technique (functional ultrasound versus conventional ultrasound) for diagnosing ACL injury. We performed meta-regression analyses for a potential source of heterogeneity.

RESULTS

Eleven (938 ultrasound/878 patients) and six articles (281 ultrasound/237 patients) were included for ACL and PCL injuries respectively. The summary sensitivity, summary specificity, and area under the hierarchical summary receiver operating characteristic for ACL and PCL injuries were 0.88 (95% confidence interval [CI], 0.81-0.93) and 0.99 (95% CI, 0.49-1.00), 0.96 (95% CI, 0.91-0.98) and 0.99 (95% CI, 0.73-1.00), and 0.97 (95% CI, 0.96-0.98) and 1.00 (95% CI, 0.99-1.00) respectively. In subgroup analysis, there was no significant difference between sensitivity (p = 0.63) and specificity (p = 0.72) of functional and conventional ultrasound. Among the various potential covariates, patient enrollment, patient position, and ultrasound performer were associated with heterogeneity in terms of sensitivity, and proportion of the ACL injury was associated with heterogeneity in terms of specificity.

CONCLUSION

Knee ultrasound demonstrates high diagnostic performance for ACL and PCL injuries, particularly when performed by experienced musculoskeletal radiologists. Future prospective studies to compare the cost- and time-effectiveness between ultrasound and magnetic resonance imaging and to determine the optimal ultrasound parameters are warranted.