ACR appropriateness criteria(®) acute trauma to the knee

Imaging Review of Snowboard Injuries

Snowboarding and skiing remain the two most popular winter sports worldwide. Musculoskeletal (MSK) injuries are common in snowboarding, and the number has increased significantly since the advent of snow parks. The number of injuries is the highest for novice snowboarders; more experienced boarders generally sustain more severe injuries. Snowboarders can experience a wide array of MSK injuries, but some injury types are more frequently encountered because of the specific injury mechanism unique to snowboarding. This article reviews the most common snowboarding injuries with a focus on the current understanding of the injury mechanism and provides an approach to imaging.

Reduction in inappropriate MRI knee studies after implementation of an appropriateness checklist: Experience at a tertiary care centre

PURPOSE

To evaluate reduction in inappropriate knee MRI requests following implementation of a mandatory knee MRI appropriateness checklist.

METHODS

A retrospective review was performed at a single tertiary care centre. A knee MRI appropriateness checklist was developed based on the ACR Appropriateness Criteria and adherence from referring physicians was mandatory. Reports from 200 consecutive knee MRI studies one year prior to implementation were compared to 200 consecutive knee MRI studies following implementation. The presence of moderate or greater osteoarthritis on MRI reports was used as a marker for inappropriate knee MRIs. Patient demographics, wait times, number of knee MRIs, and number of all MRIs at our centre over a six month period post-intervention and pre-intervention were recorded. Differences between pre-intervention and post-intervention presence of moderate or greater osteoarthritis, patient demographics, wait times, and number of MRIs analyzed.

RESULTS

A significant decrease was found in moderate or greater grade osteoarthritis following intervention, decreasing from 36.5% to 20.5% (73 studies versus 41 studies, p = 0.023). Of these, the most profound decrease occurred in studies with severe osteoarthritis, with an 80 % decrease (35 studies versus 7 studies, p < 0.001). Post intervention, 48 % fewer knee MRIs were performed in the same time interval (652 studies pre-intervention versus 336 studies post intervention, p < 0.001). No significant differences were found in the patient demographics.

CONCLUSION

Mandatory knee MRI appropriateness checklists are associated with a significant reduction in the number of inappropriate studies performed. Follow up studies will be required to assess long-term impact in a larger population.

General Practitioners Referring Adults to MR Imaging for Knee Pain: A Randomized Controlled Trial to Assess Cost-effectiveness

Purpose To determine the cost-effectiveness of early referral by the general practitioner for magnetic resonance (MR) imaging compared with usual care alone in patients aged 18-45 years with traumatic knee symptoms. Materials and Methods Cost-utility analysis was performed parallel to a prospective multicenter randomized controlled trial in Dutch general practice. A total of 356 patients with traumatic knee symptoms were included from November 2012 to December 2015 (mean age, 33 years ± 8 [standard deviation]; 222 men [62%]). Patients were randomly assigned to usual care (n = 177; MR imaging was not performed, but patients were referred to an orthopedic surgeon when conservative treatment was unsatisfactory) or MR imaging (n = 179) within 2 weeks after injury. Main outcome measures were quality-adjusted life years (QALYs) and costs from a healthcare and societal perspective. Multiple imputation was used for missing data. The Student t test was used to assess differences in mean QALYs, costs, and net benefits. Results Mean QALYs were 0.888 in the MR imaging group and 0.899 in the usual care group (P = .255). Healthcare costs per patient were higher in the MR imaging group (€1109) than in the usual care group (€837) (P = .050), mainly due to higher costs for MR imaging, with no reduction in the number of referrals to an orthopedic surgeon in the MR imaging group. Conclusion MR imaging referral by the general practitioner was not cost-effective in patients with traumatic knee symptoms; in fact, MR imaging led to more healthcare costs, without an improvement in health outcomes.

Findings Associated With Knee Pathology on MRI in Patients Without Osteoarthritis

INTRODUCTION

We conducted a retrospective study in patients with minimal or no radiographically evident knee osteoarthritis to determine whether presenting signs and symptoms were predictive of knee pathology that was evident on MRI and could be treated with nonarthroplasty knee surgery or could alter nonsurgical treatment.

METHODS

We reviewed records of patients for whom sports medicine orthopaedic surgeons had ordered an MRI of the knee. Univariate analysis identified factors that were associated with positive MRI findings (eg, surgically treatable lesion, meniscal tear) or a finding that could alter treatment. We used multivariate logistic regression to determine independent predictors of evidence of pathology on MRI.

RESULTS

Of the 434 patients in the study, 281 (64.7%) had evidence of knee pathology on MRI. Acute injury, effusion, and ligamentous instability were among the independent predictors of positive MRI results. Patients with evidence of knee pathology on MRI were more likely to have undergone surgery.

DISCUSSION

Specific aspects of patient history and physical examination are associated with evidence of knee pathology on MRI.

CONCLUSIONS

In patients without osteoarthritis, positive findings on knee MRI could be associated with a number of presenting signs and symptoms, and this information could aid physicians in deciding which patients should undergo knee MRIs. Additional prospective research is needed to validate the relationships discovered in our study.

LEVEL OF EVIDENCE

Level III retrospective study.

Traumatic Extra-capsular and Intra-capsular Floating Fat: Fat-fluid Levels of the Knee Revisited

Floating fat is a sign of acute bone injury at the knee following trauma. The goal of this article is to review the etiology, patterns, and mimickers of extra-capsular and intra-capsular floating fat, with the major emphasis on knee trauma in the acute setting. We will discuss the spectrum of multimodal imaging findings for rare presentations of extra-capsular floating fat, and contrast these with common and atypical forms of intra-capsular lipohemarthrosis, as an aid to the assessment of acute bone trauma at the knee.

Knee MRI: Vascular Pathology

OBJECTIVE

Patients who undergo knee MRI for presumed musculoskeletal disease can have unexpected vascular findings or pathology in the imaged field. Some vascular processes are limb threatening and affect treatment planning and patient outcome.

CONCLUSION

Unexpected vascular findings on knee MRI can range from incidental to symptomatic and can include such processes as variant anatomy, aneurysm, traumatic injury, and neoplasm. The assessment for vascular pathology should be a key component of every radiologist's search pattern when evaluating knee MRI.

Radiological assessment of irreducible posterolateral knee subluxation after dislocation due to interposition of the vastus medialis: a case report

Knee dislocation is a serious and relatively uncommon traumatism that every emergency room is supposed to diagnose and treat rapidly. Most of the time these dislocations reduce spontaneously or with closed reduction. If a subluxation persists, an incarceration of soft tissue in the joint must be suspected. Irreducible knee subluxations after dislocation are rare entities better described in the orthopaedic than in the radiological literature. However, the initial radiological assessment is an important tool to obtain the correct diagnosis, to detect neurovascular complications, and to plan the most suitable treatment. In cases of delayed diagnosis, the functional prognosis of the joint and even the limb may be seriously compromised primarily because of vascular lesions. Thereby, vascular imaging is essential in cases of dislocation of the knee, and we will discuss the role of angiography and the more recent use of computed tomography angiography or magnetic resonance angiography. Our patient presented with an irreducible knee subluxation due to interposition of the vastus medialis, and we will review the classical clinical presentation and 'do not miss' imaging findings on conventional radiography, computed tomography angiography, and magnetic resonance imaging. Finally, we will also report the classical imaging pathway indicated in knee dislocation, with a special emphasis on the irreducible form.

Physician provider type influences utilization and diagnostic utility of magnetic resonance imaging of the knee

BACKGROUND

Magnetic resonance imaging of the knee is expensive and is neither needed nor useful for all patients presenting with knee pain. Our objective was to determine the completeness of evaluation prior to ordering magnetic resonance imaging of the knee correlated to the ordering providers' postgraduate medical training and the rate of positive findings on the subsequent magnetic resonance imaging.

METHODS

Six hundred consecutive knee magnetic resonance images were reviewed, including 200 consecutive knee magnetic resonance imaging examinations from each of three provider types: orthopaedic surgeons, non-surgical physicians with sports medicine training, and primary care providers. Positive findings on magnetic resonance imaging were recorded as well as a history of present illness, a physical examination, and radiographs made prior to ordering magnetic resonance imaging of the knee. Patient and injury factors were recorded. Differences in patient factors, evaluation before magnetic resonance imaging, and positive findings were examined. A modified Poisson regression approach was used to determine predictors of a proper evaluation before magnetic resonance imaging and positive findings on knee magnetic resonance imaging.

RESULTS

Orthopaedists and non-surgical sports physicians were significantly more likely to document a physical examination, to evaluate radiographs made prior to ordering a magnetic resonance image, and to identify positive findings on the magnetic resonance image (all p < 0.001). In multivariate models, orthopaedists were more likely to document a history of present illness (relative risk, 1.05; p = 0.043). Compared with primary care physicians, a physical examination was more likely to be documented by both non-surgical sports medicine physicians (relative risk, 1.61; p < 0.001) and orthopaedists (relative risk, 1.60; p < 0.001) and positive magnetic resonance imaging findings were more likely to be found by non-surgical sports medicine physicians (relative risk, 1.41; p = 0.012) and by orthopaedists (relative risk, 1.44, p = 0.009). Other independent predictors of a magnetic resonance imaging study with positive findings were the presence of an acute injury by history (relative risk, 2.04; p < 0.001) and younger age (relative risk, 0.99; p = 0.021).

CONCLUSIONS

Orthopaedists and non-surgical sports physicians are more likely to perform and to document a complete evaluation prior to ordering a knee magnetic resonance image with a positive finding. More musculoskeletal training may be useful to enable primary care physicians to use magnetic resonance imaging of the knee in a more efficient manner.