Medical Student Identification of Knee Effusion by Ultrasound

Twenty-one fourth-year medical students were given a brief lecture on ultrasound of the knee and fifteen minutes of supervised ultrasound scanning of three cadavers which had been injected with saline to give varying degrees of knee effusions. Each student was then individually observed and required to scan both knees of a cadaver different from the practice cadavers and identify the patella, the femur, the quadriceps tendon and if a suprapatellar effusion was present, and which knee had the larger effusion. All twenty-one students correctly identified all anatomical structures, suprapatellar effusions, and which knee had the larger effusion. Identifying a knee effusion can be an important clinical finding in diagnosing and managing a patient with knee complaints. Fourth-year medical students can learn to identify knee effusions with ultrasound following a brief introductory lecture and hands-on scanning practice session. 1. Introduction Recognizing an effusion in a symptomatic knee is an important finding in many rheumatologic conditions. It is not always easy to determine if a knee effusion is present on physical examination, especially if the effusion is small or the patient is obese. Ultrasound is a safe, quick, and accurate method to identify a knee effusion. A study was conducted to determine if after a brief musculoskeletal ultrasound workshop, fourth-year medical students with little ultrasound experience could learn to scan and identify anatomical landmarks in the knee, and determine if an effusion was present. 2. Subjects and Methods Twenty-one fourth-year medical students volunteered to participate in the study. Each student completed a short questionnaire about their prior ultrasound experience. The group attended a thirty-minute didactic PowerPoint presentation consisting of a brief introduction of the physics of ultrasound, the anatomy of the knee, ultrasound scanning techniques of the knee and a review of normal and abnormal ultrasound images, including knee effusions. After the presentation, students observed a faculty member performing a suprapatellar longitudinal scan of the knee of a cadaver that had previously been injected with normal saline to produce a small effusion in the suprapatellar bursa. The students then had approximately 15 minutes of supervised scanning on three cadavers which had been injected with saline to give varying degrees of knee effusions. Students were taught to identify the femur, the quadriceps tendon, the patella, and a suprapatellar bursa effusion, if present. After the instructional session, each student