Evidence-based practice in the utilization of knee radiographs--a survey of all members of the British Orthopaedic Association

An assessment of the dose and image quality difference between AP and PA positioned adult radiographic knee examinations

INTRODUCTION

Knee X-rays are a standard examination to diagnose multiple conditions ranging from traumatic injuries, degeneration, and cancer. This study explores the differences between adult Anterior-Posterior (AP) and Posterior-Anterior (PA) weight-bearing knee examinations using absorbed radiation dose data and image quality.

METHODS

The study modelled and compared AP and PA knee X-ray radiation dose data using Monte-Carlo software, an Ion Chamber, and thermoluminescence dosemeters (TLDs) on a Rando phantom. Imaging parameters used were 66kVp, 4mAs, 100cm distance and 13 × 24cm collimation. The interval data analysis used a two-tailed t-test. The image quality of a sample of the AP and PA knee X-rays was assessed using Likert 5-point ordinal Image Quality Scoring (IQS) and the Wilcoxon matched pairs test.

RESULTS

Monte-Carlo modelling provided limited results; the Ion Chamber data for absorbed dose provided no variation between AP and PA positions but was similar to the AP TLD dose. The absorbed doses recorded with batches of TLDs demonstrated a 27.4% reduction (46.1μGy; p=0.01) in Skin Entrance Dose (ESD) and 9 - 58% dose reduction (1.6 - 16.4μGy; p=0.00-0.2) to the tissues and organs while maintaining diagnostic image quality (p=0.67).

CONCLUSION

The study has highlighted the various challenges of using different dosimetry approaches to measure absorbed radiation dose in extremity (knee) X-ray imaging. The Monte-Carlo simulated absorbed knee dose was overestimated, but the simulated body organ/tissue doses were lower than the actual TLD absorbed doses. The Ion Chamber absorbed doses did not differentiate between the positions. The TLD organ/tissue absorbed doses demonstrated a reduction in dose in the PA position compared to the AP position, without a detrimental effect on image quality. The study findings in laboratory conditions raise awareness of opportunities and potential to lower radiation dose, with further study replicated in a clinical site recommended.

Comparison of Joint Space Width Determinations in Grade I and II Knee Osteoarthritis Patients Using Manual and Automatic Measurements

Background:

Examination of the knee to assess the narrowing of the joint gap or joint space width (JSW) is commonly done by manually checking radiographs and measuring the JSW using a ruler.

Objective:

This study aims to compare manual and automatic measurements with the diagnosis of grade I and grade II knee osteoarthritis.

Material and Methods:

In this cross-sectional study, 40 patients with the criteria for primary osteoarthritis (OA), aged 46 to 65 years old had knee OA grades of either I or II. The knee image was evaluated by a computer program and a radiologist manually viewing and measuring the JSW joint gap using a ruler.

Results:

The results showed there were no differences in the measurement of JSW medial and JSW lateral manually in grade I and grade II knee OA, at p=0.605 and p=0.344, respectively. Whereas in the automatic measurements, there was a difference between JSW medial and lateral JSW in grade I and grade II knee OA, each with p<0.001. The manual JSW measurement between medial JSW and lateral JSW in grade I and II showed that the medial and lateral knee joints have a similar distance. In the automatic, the average value of measurement lateral JSW in OA grades I and II was greater than the medial JSW.

Conclusion:

Automatic measurements showed that both of medial and lateral JSW at grade II OA knee were narrower than the results at grade I. Automatic measurement of JSW results was more consistent than the manual measurement method.

The Combination of the Tunnel View and Weight-Bearing Anteroposterior Radiographs Improves the Detection of Knee Arthritis

Imaging used for the evaluation of knee pain has historically included weight-bearing anteroposterior (AP), lateral, and sunrise radiographs. We wished to evaluate the utility of adding the weight-bearing (WB) posteroanterior (PA) view of the knee in flexion. We hypothesize that (1) the WB tunnel view can detect radiographic osteoarthritis (OA) not visualized on the WB AP, (2) the combination of the AP and tunnel view increases the radiographic detection of OA, and (3) this may provide additional information to the clinician evaluating knee pain. We retrospectively reviewed the WB AP and tunnel view radiographs of 100 knees (74 patients) presenting with knee pain and analyzed for evidence of arthritis. The combination of the WB tunnel view and WB AP significantly increased the detection of joint space narrowing in the lateral (p < 0.001) and medial (p = 0.006) compartments over the AP view alone. The combined views significantly improved the identification of medial subchondral cysts (p = 0.022), sclerosis of the lateral tibial plateau (p = 0.041), and moderate-to-large osteophytes in the medial compartment (p = 0.012), intercondylar notch (p < 0.001), and tibial spine (p < 0.001). The WB tunnel view is an effective tool to provide additional information on affected compartments in the painful knee, not provided by the AP image alone.

The utility of plain radiographs in the initial evaluation of knee pain amongst sports medicine patients

PURPOSE

To evaluate whether screening radiographs as part of the initial workup of knee pain impacts clinical decision-making in a sports medicine practice.

METHODS

A questionnaire was completed by the attending orthopaedic surgeon following the initial office visit for 499 consecutive patients presenting to the sports medicine centre with a chief complaint of knee pain. The questionnaire documented patient age, duration of symptoms, location of knee pain, associated mechanical symptoms, history of trauma within the past 2 weeks, positive findings on plain radiographs, whether magnetic resonance imaging was ordered, and whether plain radiographs impacted the management decisions for the patient. Patients were excluded if they had prior X-rays, history of malignancy, ongoing pregnancy, constitutional symptoms as well as those patients with prior knee surgery or intra-articular infections. Statistical analyses were then performed to determine which factors were more likely do correspond with diagnostic radiographs.

RESULTS

Overall, initial screening radiographs did not change management in 72 % of the patients assessed in the office. The mean age of patients in whom radiographs did change management was 57.9 years compared to 37.1 years in those patients where plain radiograph did not change management (p < 0.0001). Plain radiographs had no impact on clinical management in 97.3 % of patients younger than 40. In patients whom radiographs did change management, radiographs were more likely to influence management if patients were over age forty, had pain for over 6 months, had medial or diffuse pain, or had mechanical symptoms. A basic cost analysis revealed that the cost of a clinically useful radiographic series in a patient under 40 years of age was $7,600, in contrast to $413 for a useful series in patients above the age of 40.

CONCLUSION

Data from the current study support the hypothesis that for the younger patient population, routine radiographic imaging as a screening tool may be of little clinical benefit. Factors supporting obtaining screening radiographs include age greater than 40, knee pain for greater than 6 months, the presence of medial or diffuse knee pain, and the presence of mechanical symptoms.

LEVEL OF EVIDENCE

II.

A skyline-view imaging technique for axial projection of the patella: a clinical study

Our purpose in this study was to evaluate the clinical usefulness of a new skyline-view imaging technique for axial projection of the patella with use of the anterior border of the patella and tibial tuberosity as position indicators. Our database consisted of pairs of axial images of the patella of the same patients, obtained with use of conventional and new techniques for the radiographic diagnosis of knee-joint diseases. A total of 118 pairs of knee images were obtained from 103 patients ranging in age from 16 to 86 years (mean age 49.7 years). The patellar axial positioning errors were determined in each of the images obtained with the two techniques. The relative error according to the patellar tilt was determined from each of the axial images of the patellas of the same patients obtained with the conventional and new techniques for the radiographic diagnosis of knee-joint diseases. The patellar axial positioning error was 0.40 with the conventional technique, whereas that with the new technique was significantly different at 0.30. This clinical study confirmed that the new skyline-view imaging technique, which uses the anterior border of the patella and the tibial tuberosity as position markers that can be confirmed by palpation, provides more accurate axial images than the conventional imaging technique.

Comparative analysis between radiographic views for knee osteoarthrosis (bipedal AP versus monopedal AP)

Objective

A comparative analysis by applying the criteria of the original classification Ahlbäck in the anteroposterior (AP) bipedal knee in extension and anteroposterior (AP) monopodal knee in symptomatic knee arthrosis. With this analysis we intend to observe the agreement, any advantage or difference between the incidence and degree of joint involvement between the orthopedic surgeons and radiologists with the referring physician.

Methods

From January 2012 to March 2012, was a prospective study of 60 symptomatic arthrosis knees (60 patients), clinically selected group of outpatient knee and radiographic proposals submitted to the search. Of the 60 patients, 39 were female and 21 male, mean age 64 years (ranging from 50 to 84 years). Of the 60 knees studied, 37 corresponded to the right side and 23 on the left side. Statistical analysis was performed by Kappa statistics, which evaluates the interobserver agreement for qualitative data.

Results

According to the scale of Ahlbäck, there was a significant agreement (p < 0.0001) intra-observer in the classification of knee osteoarthritis among the five evaluators. There was a significant agreement (p < 0.0001) with inter-observer referring physician in the incidence of AP monopodal and AP bipedal for the four raters.

Conclusion

The study found no difference between the incidence in the AP monopodal versus AP bipedal in osteoarthritis of the knee.

Use of knee magnetic resonance imaging by primary care physicians in patients aged 40 years and older

BACKGROUND

Criteria are needed for primary care providers such that they can evaluate age-related knee pain in a cost-effective manner. This study examined (1) in what percentage of patients are appropriate radiographic views of the knee ordered before magnetic resonance imaging (MRI) for knee pain, (2) specialists' retrospective evaluation for appropriate utilization of MRI in knee pain, and (3) in what manner would the MRIs have altered diagnosis and management of knee disorders.

HYPOTHESIS

Primary care providers underuse appropriate radiographs-especially, flexion weightbearing posteroanterior films-and overuse MRIs when evaluating older patients with knee pain.

STUDY DESIGN

Case control.

METHODS

The authors performed a retrospective analysis of 100 patients older than 40 years with knee MRIs. Patient encounters with primary care physicians were reviewed. Given available information, specialists then formulated a pre- and post-MRI diagnosis and treatment plan and indicated whether the MRI would have altered their treatment.

RESULTS

Only 12 of 100 MRIs would have been ordered by an orthopaedist given the documented data. No MRIs would have been ordered in the 19 patients aged 60 years or older. Among 44 radiographs ordered, only 7 were flexion weightbearing. The most common pre-MRI diagnoses made by primary care providers were joint pain (22%) and meniscus injury (24%); the most common post-MRI diagnoses were osteoarthritis (40%) and degenerative meniscus injury (23%). In contrast, the 2 most common pre- and post-MRI diagnoses by specialists were osteoarthritis (28% and 37%, respectively) and degenerative meniscus injury (23% and 24%, respectively). Also, referrals to specialists increased from 9% pre-MRI to 76% post-MRI.

CONCLUSION

Primary care providers may be overusing knee MRIs and underusing flexion weightbearing posteroanterior radiographs in patients older than 40 years with knee pain.

CLINICAL RELEVANCE

Primary care providers should strongly consider not ordering knee MRI in patients with radiographic evidence of degenerative changes.

The standing fixed flexion view detects narrowing of the joint space better than the standing extended view in patients with moderate osteoarthritis of the knee

BACKGROUND AND PURPOSE

It is unclear whether osteoarthritis (OA) of the knee is seen better in standing flexion position radiographs than in the standing extended view. We assessed the value of standing flexion views.

PATIENTS AND METHODS

We retrospectively evaluated 1,090 radiographs of 545 consecutive knees with non-traumatic knee pain, comparing standing fixed flexion view (FFV) and standing extended view (SEV). OA was classified according to the Kellgren-Lawrence (KL) radiographic grading scale and joint space widths were measured.

RESULTS

Medial joint space width was lower on average in the FFV, with the greatest difference in KL II knees. Medial full-thickness loss of cartilage was also seen more often in the FFVs of knees with moderate OA (KL II-III) than in the SEVs (6% vs. 19%).

INTERPRETATION

Using FFV, there is no need to measure the exact knee flexion angle to use fluoroscopy. In earlier studies, the FFV has been found to be reproducible and easy to use in clinical practice. We recommend using flexion views when deciding the appropriate type of intervention in patients with OA. Full-thickness loss of cartilage in particular is better seen in the flexion view, which may be helpful if planning unicompartmental knee arthroplasty.