ACR Appropriateness Criteria Acute Trauma to the Knee

Skyline view of the patella does not increase fracture detection: A non-inferiority diagnostic study

PURPOSE

Patella fractures are frequent injuries in the adult population. Initial study is made by plain radiographs and the standard set includes the skyline view of patella. Recommendation for use of this projection is variable among the experts, without data that support its performance in the diagnosis of patella fractures. The main purpose of this study was to determine the sensitivity of the antero-posterior and lateral view of the knee, without skyline view, in the diagnosis of patella fracture.

METHODS

A retrospective non-inferiority diagnostic study was designed with all the knee trauma adult patients of an Emergency Department in a single center in five years. A random sample of all the consecutive patella fracture cases were taken to elaborate the case group. The control group was matched by sex and age. Two blinded orthopedic surgeons reviewed the cases and control radiographs and defined the presence of fracture, with or without skyline view, with a wash-out time of three weeks between the two evaluations. Non-inferiority was defined a priori at 90% of minimum sensitivity.

RESULTS

140 patients were evaluated (70 cases and 70 controls). Sensitivity of the set without skyline view was 92.86% (CI 95% 0.90 - 0.96) and the standard set was 97.86% (CI 95% 0.96 - 0.99), without significant differences (p = 0.1) CONCLUSION: Sensitivity of the plain radiograph set without skyline view is non-inferior to the standard set. The routine use of skyline view when suspecting patella fractures is questionable.

Changing primary care requesting practices for MRI knee: A quality improvement project

OBJECTIVES

The objectives of this work were first to examine referral practices from primary care for MRI knee in patients ≥45 years old and then to develop a new referral pathway to reduce the number of inappropriate MRI knee referrals. Following this, the aim was to re-assess the effect of the intervention and identify further areas for improvement.

METHODS

A baseline retrospective analysis of knee MRIs requested from primary care in symptomatic patients ≥45years over a two-month period was undertaken. A new referral pathway was implemented in consensus with orthopaedic specialists and the clinical commissioning group (CCG), via the CCG resource webpage and local education. Following implementation, a repeat data analysis was undertaken.

RESULTS

The number of MRI knees acquired from primary care referrals reduced by 42% after the new pathway was implemented. 67% (46/69) were compliant with the new guidelines. The number of patients having an MRI knee without a prior plain radiograph was 14/69 (20%) compared to 55/118 (47%) prior the pathway changes.

CONCLUSION

The new referral pathway reduced the number of knee MRI acquisitions in primary care patients ≥45 years by 42%. Changing the pathway has decreased the number of patients undergoing MRI knee without a prior radiograph from 47% to 20%. These outcomes bring our standards towards the evidence-based recommendations of the Royal College of Radiology and have reduced our outpatient waiting list for MRI knee.

IMPLICATIONS FOR PRACTICE

Implementing a new referral pathway with the local CCG can successfully reduce the number of inappropriate MRI knee acquisitions from primary care referrals in older symptomatic patients.

The accuracy of routine knee MR imaging in detection of acute neurovascular injury following multiligamentous knee injury

OBJECTIVE

To assess the accuracy of routine knee MRI in detecting acute popliteal artery and/or common peroneal nerve (CPN) dysfunction following multiligamentous knee injury (MLKI), with correlation of MRI findings to clinical outcome.

MATERIALS AND METHODS

Routine MRI knee examinations in 115 MLKI patients (54/115 with acute neurovascular injury, 61/115 without neurovascular injury) were retrospectively reviewed. Cases were classified by injury mechanism and ligamentous injuries sustained. MRI examinations were reviewed by two readers for vascular (arterial flow void, arterial calibre, intimal flap, perivascular hematoma) and CPN (intraneural T2-hyperintensity, calibre, discontinuity, perineural hematoma) injuries. Accuracy of routine knee MRI in the diagnosis of acute neurovascular injury and correlation of MRI findings to clinical outcome were evaluated.

RESULTS

Patients included 86/115 males, mean age 33 years. The accuracy of MRI in diagnosis of acute CPN injury was 80.6%, 83.6% (readers 1 and 2): sensitivity (78%, 79.7%), specificity (80%, 86.7%), PPV (78%, 82.5%), and NPV (82.7%, 84.4%). Increased intraneural T2 signal showed a significant correlation to acute CPN dysfunction (p < 0.05). MRI was 75%, 69.8% (readers 1 and 2) accurate in detecting acute vascular injury: sensitivity (73.3%, 86.7%), specificity (75.2%, 67.3%), PPV (30.5%, 36.1%), and NPV (95%, 97.1%). No MRI features of vascular injury showed a statistical correlation with clinical outcome. Neurovascular complications were more common in ultra-low-energy injuries and KD-V3L pattern of ligament disruption.

CONCLUSION

Routine MRI is of limited accuracy in assessing vascular complication, but higher accuracy in assessing CPN injury following MLKI. Increased intraneural T2 signal on conventional knee MR imaging shows statistically significant association with clinically documented acute CPN dysfunction following MLKI.

Treatment of Osteochondral Fractures After Acute Patellofemoral Instability: A Critical Analysis Review

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An osteochondral fracture (OCF) of the patella or the femur is a frequent sequela after an episode of acute patellofemoral instability.

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Patients commonly present with anterior knee pain after direct trauma to the patella or a noncontact twisting injury.

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Radiographs and magnetic resonance imaging (MRI) are the most common imaging modalities that are used to diagnose OCFs.

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Arthroscopy may be indicated in cases of displaced OCFs, and the decision regarding osteochondral fragment fixation or loose body removal depends on fragment size, location, and extent of injury.

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Most of the current literature suggests worse outcomes for patients with OCFs who undergo nonoperative treatment, no significant differences in outcomes for patients sustaining an acute patellar dislocation with or without an OCF, and inconclusive results concerning outcomes for patients treated with loose body removal compared with fixation.

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Current outcome data are limited by studies with low levels of evidence; therefore, well-designed randomized controlled trials are needed.

Incidence Rates of Surgery After Knee MRI: Association According to Referring Physician Type and Patient's Age and Sex

Background

The utility of magnetic resonance imaging (MRI) in the primary care setting is uncertain, with a perception that there is less likelihood for surgery after MRI ordered by general practitioners (GPs) when compared with orthopaedic surgeons and sports medicine physicians. Additionally, the influence of patient age and sex on subsequent surgical intervention is currently unknown.

Purpose/Hypothesis

The purpose of this study was to compare surgical incidence after MRI referrals by orthopaedic surgeons, GPs, and sports medicine physicians, including a subset analysis for GP patients based on type of approval given by the radiologist. The authors also wanted to explore the association of age and sex on subsequent surgical intervention. They hypothesized that surgical incidence after MRI ordered by orthopaedic surgeons and sports medicine physicians would be higher than after MRI ordered by GPs.

Study Design

Cohort study; Level of evidence, 3.

Methods

Knee MRI referrals by the 3 physician cohorts during May to December 2017 were assessed. For GP patients, the types of approval or recommendation from a radiologist were categorized. Subsequent surgical intervention status was then compared among referral groups up to 2 years after MRI. Associations of age and sex with surgical occurrence were also assessed. Chi-square test, analysis of variance, and univariate/multivariable logistic regression were used for statistical analysis.

Results

Overall, 407 referrals were evaluated (GP, n = 173; orthopaedic, n = 176; sports medicine, n = 58). Surgical incidence was not significantly higher for orthopaedic and sports medicine than GP referrals at 3 months (10%, 3%, and 6%, respectively; P = .23), 6 months (20%, 17%, and 15%; P = .49), and 2 years (30%, 35%, and 24%; P = .25). Surgical incidence for GP patients was higher after discussion with a radiologist or when evaluating specific pathology on prior imaging versus less defined reasons (30.4% vs 15.7%, respectively; P = .03). Surgical incidence was lower for older patients (11% vs 31% for >60 years vs all other age groups combined; P = .002), and women were less likely to undergo surgery than men (22% vs 35%, respectively; P = .008).

Conclusion

Surgical incidence after MRI was likely appropriately lower for older patients. Lower incidence for female patients is of uncertain cause and warrants further study.

Radiographic clues to the unstable knee: are findings of trochlear dysplasia on lateral knee radiographs reliable and predictive of patellar dislocation?

BACKGROUND

Trochlear dysplasia (TD) is a key predisposing risk factor for patellar instability (PI) and lateral patellar dislocation (LPD) injuries. It is useful to understand the reliability of radiographic findings of TD and the accuracy of knee radiographs in diagnosing patients with recent LPD.

PURPOSE

The purposes of our study are to evaluate the inter-rater reliability of specific radiographic signs of PI and staging of TD between radiologists and orthopedic surgeons, and to identify which findings are associated with recent LPD.

METHODS

This retrospective study comprised 336 patients aged 8 to 18 who obtained knee radiographs over a 3-year period. Two radiologists and two orthopedic surgeons, blinded to patient history, examined radiographs for indicators of PI. Using data from 19 confirmed LPD cases and 317 controls, inter-observer agreement (kappa, Pearson's correlation coefficient) was assessed, as was the odds ratio for likelihood of LPD.

RESULTS

There was nearly perfect agreement between radiologists for patella-tendon ratios (Pearson's correlation coefficient 0.8377, P < 0.0001) and discrimination between normal knees and high-grade TD (kappa 0.9213, P < 0.0001). There is fair agreement between radiologists and surgeons distinguishing between normal knees and high-grade TD (kappa 0.5843, P < 0.0001). Lateral knee radiographs interpreted as high-grade TD were highly predictive of LPD (odds ratio 7.58-54.8) among all readers.

CONCLUSIONS

There is high agreement between radiologists when evaluating lateral knee radiographs for signs of TD, validating the results of prior literature. Radiographic findings TD, patella alta, and effusion are variable predictors of recent LPD, greatest among patients with TD.

CT diagnosis of bucket handle meniscus tear

Bucket handle meniscus tears are difficult to diagnosis and are one of the most frequently missed tear patterns on magnetic resonance imaging (MR). However, this meniscal injury often requires arthroscopic intervention and preoperative characterization of the tear is important to orthopedic surgeons for treatment planning. MR is currently the best imaging modality for evaluating meniscal tears, but trauma patients in the emergency room more often undergo radiographs and further evaluation with computed tomography (CT) exams. To date, there is one study from 1988 that reported the value of CT in diagnosing bucket handle meniscus tears. We present an informative case of bucket handle meniscus tear after acute traumatic knee injury that was diagnosed on CT and later confirmed on arthroscopy.

Hoffa fracture accompanied by dissection of the popliteal artery

After a high-energy trauma, a 37-year-old motorcyclist presented to the emergency ward with a Hoffa fracture of the lateral femoral condyle of the right knee. Following admission, the patient developed a pale, cold and pulseless right foot. CT angiography scan showed a 5 cm dissection of the popliteal artery. Emergency arterial reconstruction was performed and the Hoffa fracture was repaired in a second stage. To our knowledge, this is the first report of a patient with a Hoffa fracture accompanied by a popliteal artery dissection.

Hip and Knee Injuries

Hip and knee injuries are a common presenting concern for patients to a primary care office. This pathology represents a large differential and it can often be a diagnostic challenge for providers to determine the etiology of a patient's symptoms. This article discusses several of the most common causes for hip and knee pain while providing an evidence based review of physical examination maneuvers, imaging studies and treatment modalities to assist a primary care provider when encountering active patients with underlying hip or knee pain.

Preoperative MRI for the Multiligament Knee Injury: What the Surgeon Needs to Know

The multiligament knee injury is devastating and potentially limb threatening. Preoperative magnetic resonance imaging for the evaluation of the multiligament knee injury is an invaluable clinical tool, and when the radiologist is familiar with how certain injury patterns influence management, optimal outcomes can be achieved. We provide a detailed description of the relationship between salient imaging features of the multiligament knee injury, focusing on the preoperative magnetic resonance imaging, and their influence on clinical decision-making.

Synthetic MRI of the Knee: Phantom Validation and Comparison with Conventional MRI

Purpose To test the hypothesis that synthetic MRI of the knee generates accurate and repeatable quantitative maps and produces morphologic MR images with similar quality and detection rates of structural abnormalities than does conventional MRI. Materials and Methods Data were collected prospectively between January 2017 and April 2018 and were retrospectively analyzed. An International Society for Magnetic Resonance in Medicine-National Institute of Standards and Technology phantom was used to determine the accuracy of T1, T2, and proton density (PD) quantification. Statistical models were applied for correction. Fifty-four participants (24 men, 30 women; mean age, 40 years; range, 18-62 years) underwent synthetic and conventional 3-T MRI twice on the same day. Fifteen of 54 participants (28%) repeated the protocol within 9 days. The intra- and interday agreements of quantitative cartilage measurements were assessed. Contrast-to-noise (CNR) ratios, image quality, and structural abnormalities were assessed on corresponding synthetic and conventional images. Statistical analyses included the Wilcoxon test, χ² test, and Cohen Kappa. P values less than or equal to .01 were considered to indicate a statistically significant difference. Results Synthetic MRI quantification of T1, T2, and PD values had an overall model-corrected error margin of 0.8%. The synthetic MRI interday repeatability of articular cartilage quantification had native and model-corrected error margins of 3.3% and 3.5%, respectively. The cartilage-to-fluid CNR and menisci-to-fluid CNR was higher on synthetic than conventional MR images (P ≤ .001, respectively). Synthetic MRI improved short-tau inversion recovery fat suppression (P ˂ .01). Intermethod agreements of structural abnormalities were good (kappa, 0.621-0.739). Conclusion Synthetic MRI of the knee is accurate for T1, T2, and proton density quantification, and simultaneously generated morphologic MR images have detection rates of structural abnormalities similar to those of conventional MR images, with similar acquisition time. © RSNA, 2018.

Feasibility of synthetic MRI in knee imaging in routine practice

Background

Synthetic magnetic resonance (MR) is a method allowing reduction of examination time and access to quantitative imaging.

Purpose

This study sought to assess the image quality and diagnostic accuracy of synthetic magnetic resonance imaging (MRI) compared to standard MRI in patients with knee pain.

Material and Methods

In total, 22 patients underwent standard 1.5 knee MRI with an added synthetic sequence. Quantitative T1, T2, and proton density (PD) images were generated synthetically; T1, PD, and short tau inversion recovery (STIR) weighted images were created with chosen echo time (TE), repetition time (TR), and inversion time (TI). Two blinded musculoskeletal radiologists evaluated the overall sequence quality, visualization of anatomic structures, and presence of artifacts using a 3-point score.

Results

The synthetic sequence was acquired in 39% less time than the conventional MRI. Synthetic PD, T1, and STIR images were rated fair (2%, 5%, and 2%, respectively) or good quality (98%, 95%, and 98%, respectively), despite the presence of popliteal artery artifacts. Cartilage and meniscus were well visualized in all cases. Anterior cruciate ligament visualization was rated poor in 7%, 14%, and 30% of PD, STIR, and T1 images, respectively.

Conclusion

Our pilot study confirmed the feasibility of synthetic MRI in knee examinations, proving faster and achieving appropriate quality and good diagnostic confidence.

Traumatic knee injury: correlation of radiographic effusion size with the presence of internal derangement on magnetic resonance imaging

PURPOSE

Traumatic knee injury is a common clinical presentation. However, knee internal derangement often goes undiagnosed on physical exam. The authors hypothesize that patients with suprapatellar joint effusion greater than 10 mm anteroposterior diameter on lateral radiograph have a high likelihood of knee internal derangement on magnetic resonance imaging.

MATERIALS AND METHODS

A retrospective review of knee radiographs and magnetic resonance imaging in 198 patients age 18-40 years with acute knee injury was performed. Suprapatellar effusion diameter on lateral radiography was correlated to the presence of internal derangement on magnetic resonance imaging. Magnetic resonance imaging anteroposterior effusion size at four locations was correlated to radiographic suprapatellar effusion measurements.

RESULTS

Logistic regression showed a positive correlation between radiographic effusion size and the presence of internal derangement on magnetic resonance exams (p value < 0.001). Radiographic effusion > 10 mm was established as a positive test, yielding test sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 55, 96, 93, 71, and 77%, respectively. Statistical analysis showed the radiographic anteroposterior effusion diameter most closely approximated the magnetic resonance effusion diameter at the lateral patellofemoral recess.

CONCLUSIONS

This study shows that knee radiography is a highly specific screening test for internal derangement in patients less than 40 years old with acute knee injury. In this patient population, knee effusion > 10 mm on lateral radiograph should prompt consideration for knee magnetic resonance examination. Adopting this approach as a clinical guideline has the potential to decrease delayed diagnosis, improve patient outcomes, and decrease cost-associated disability.

Review article: Best practice management of common knee injuries in the emergency department (part 3 of the musculoskeletal injuries rapid review series)

Knee injuries are a common presentation to the ED and are often difficult to assess and definitively diagnose due to the patient's acute pain, effusion and guarding. The quality of ED care provided to patients with fractures or soft tissue injuries of the knee is critical to ensure the best possible outcomes for the patient. This rapid review investigated best practice for the assessment and management of common knee injuries in the ED. Databases were searched in 2017, including PubMed, CINAHL, EMBASE, TRIP and the grey literature, including relevant organisational websites. Primary studies, systematic reviews and guidelines were considered for inclusion. English-language articles published in the past 12 years that addressed the acute assessment, management, follow-up plan or prognosis were included. Data extraction of included articles was conducted, followed by quality appraisal to rate the level of evidence where possible. The search revealed 2250 articles, of which 54 were included in the review (n = 8 primary articles, n = 28 systematic reviews, n = 18 guidelines). This rapid review provides clinicians managing fractures and soft tissue injuries of the knee in the ED, a summary of the best available evidence to enhance the quality of care for optimal patient outcomes. There is consistent evidence to support undertaking a thorough history and physical examination, including the application of special tests and clinical decision rules for imaging. In the undifferentiated knee injury, expedited follow up and further imaging is recommended to improve patient outcomes and cost-effectiveness.

What Is the Diagnostic Accuracy of the Duck Walk Test in Detecting Meniscal Tears?

BACKGROUND

Clinical weightbearing provocation tests, like the duck walk test, may be of value in diagnosing or screening for medial meniscal tears. However, evidence of the diagnostic accuracy of the duck walk test is lacking.

QUESTIONS/PURPOSES

(1) To determine the sensitivity and specificity of the duck walk test in diagnosing medial meniscal tears. (2) To determine whether tear location, tear cause (traumatic versus degenerative), and ACL insufficiency were associated with differences in the sensitivity and specificity of the test.

METHODS

A convenience sample of 136 patients of all ages was retrospectively analyzed by evaluating the outpatient knee clinic appointment list of one orthopaedic surgeon for patients with a broad range of knee injuries who had a prior MRI before (24%) or after (76%) physical examination and had a duck walk test stated in their patient records. Of 230 patients with MRI requested by one orthopaedic surgeon attributable to knee complaints, 136 (59%) fulfilled the inclusion criteria; 70 (52%) patients were male and 66 (49%) were female, with a mean age of 42 (± SD 14) years. The duck walk test was performed in case of suspected meniscal injury, based on mechanism of injury, general joint line pain, and/or mechanical complaints (ie, locking, giving away). The test is performed by squatting and "waddling" before rising and is positive in case of general joint line pain or painful "clicking". Interobserver repeatability was not evaluated, but the test is well defined and leaves little room for difference in interpretation. Diagnostic accuracy measures were evaluated. Since the convenience sample in this study consisted of patients who had a duck walk test and MRI, and a positive result of the duck walk test almost certainly increased the probability that MRI would be ordered in the majority (76%) of the patients, the test properties calculated here-especially sensitivity-should be considered inflated.

RESULTS

The calculated sensitivity of the duck walk test was 71% (95% CI, 59%-81%) and there was low specificity of 39% (95% CI, 27%-52%). We found no difference in sensitivity between medial (67%; 95% CI, 51%-80%) and lateral (76%; 95% CI, 50%-92%; p = 0.492) meniscal tears. With the numbers available, we compared these patients with patients without a history of trauma and with an intact ACL. We found no difference among patients with traumatic tears (79%; 95% CI, 59%-91%; p = 0.253) and in patients with ACL tears (77%; 95% CI, 46%-94%; p = 0.742).

CONCLUSIONS

Because of the issue of verification bias, the actual sensitivity of this test in practice is likely much lower than the calculated sensitivity we observed. In addition, the test did not seem to perform better in patients with trauma or ACL insufficiency, nor was it more effective in detecting medial than lateral tears, although the numbers on some of those comparisons were rather small. Based on these results, we conclude that used alone, the duck walk test likely has little value in practice as a screening test. However, it is conceivable that it could be used in combination with other provocative tests for screening purposes. Future studies might consider using it as a means to best identify which patients should undergo MRI for the possibility of a meniscal tear.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Comparison of Tibial Intramedullary Nailing Guided by Digital Technology Versus Conventional Method: A Prospective Study

Background

This prospective study aimed to compare clinical effects of intramedullary nailing guided by digital and conventional technologies in treatment of tibial fractures.

Material/Methods

Thirty-two patients (mean age 43 years, 18 males and 14 females) who were treated for tibial fractures from October 2010 to October 2012 were enrolled. They were sequentially randomized to receive intramedullary nailing guided by either digital technology (digital group, n=16) or conventional technology (conventional group, n=16). The operation time, fluoroscopy times, fracture healing time, distance between the actual and planned insertion point, postoperative lower limb alignment, and functional recovery were recorded for all patients.

Results

The mean operation time in the digital group was 43.1±6.2 min compared with 48.7±8.3 min for the conventional technology (P=0.039). The fluoroscopy times and distance between the actual and planned insertion point were significantly lower in the digital group than in the conventional group (both P<0.001). The accuracy rate of the insertion point was 99.12% by digital technology. No difference was found in fracture healing time and good postoperative lower limb alignment between the digital and conventional groups (P=0.083 and P=0.310), as well as the effective rate (100% vs. 87.50%, P=0.144).

Conclusions

Intramedullary nailing guided by digital technology has many advantages in treatment of tibial fractures compared to conventional technology, including shorter operation time, reduced fluoroscopy times, and decreased distance between the actual and planned insertion point of the intramedullary nail.