Role of Ultrasound in the Evaluation of Painful Knee. A Comparative Study to MRI

Abstract

Background: One of the frequent musculoskeletal problems is knee pain. The trend of increasing of knee pain among the populations is noted. Therefore, choosing a reliable screening tool with reasonable cost is mandatory. Although magnetic resonance imaging (MRI) is the gold standard imaging modality for knee soft tissue structures, it has been widely abused with its high cost. Ultrasound is an established modality to image the soft tissue structures of the knee. Objective: To show the role of ultrasound (US) in evaluating of knee pain and comparing the results with magnetic resonance imaging (MRI). Patients and methods: This study included 40 patients (18 males and 22 females) with an age ranging from 15-69 years. This study was carried out at the Radiology Department of Al-Azhar University Hospitals for ultrasonography and MRI examination during the period from October 2019 to November 2020. Results: Regarding meniscal horn tear, ultrasound detected tear in 2 cases, while MRI detected tear in 5 cases. Regarding meniscal horn degeneration, Ultrasound detected degeneration in 1 case, while magnetic resonance imaging detected degeneration in 6 cases. These results indicated that sonography was not accurate enough to be used as the only modality for diagnosing lesions of the knee menisci. Regarding medial collateral ligament (MCL) injury, ultrasound detected medial collateral ligament injury in 3 cases, while magnetic resonance imaging detected medial collateral ligament injury in 4 cases. The majority of the knees with osteoarthritis (OA) had effusion using ultrasound (100%) and magnetic resonance imaging (100%). Synovial thickening observed on ultrasound and magnetic resonance imaging. This study confirmed that there was a significant correlation between the magnetic resonance imaging and ultrasound techniques for evaluating the cartilage and soft tissue changes in the patients with knee osteoarthritis. Conclusion: Ultrasound is an effective imaging modality that can be suitable as a screening tool for patients having knee pain. Knee US has reasonable accuracy in detecting collateral ligament and meniscal pathology. US with the advantages of being widely available lower in cost and with no contraindications should be the first modality of choice in evaluating knee pain. MRI can be reserved for equivocal US results.