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Point of care ultrasound or POCUS is easy to use, has enhanced mobility due to the smaller equipment needed, and may be carried out in a variety of settings. It is also far safer and cheaper than imaging techniques like computer tomography.
POCUS can be helpful when certain exam findings are difficult to appreciate by palpation, percussion, or auscultation and can facilitate learning elements of the cardiac, pulmonary, abdominal, musculoskeletal, and vascular exams.
With ultrasound, the anatomy of the knee and shoulder are easily visualized, thus allowing better understanding of the anatomic basis for many exam maneuvers. Ultrasound allows for the detection of tendon, ligament, and muscle injury, the presence of fluid, structural abnormalities, and bone fractures in the musculoskeletal region.
In the case of the knee, ultrasound is helpful in the detection of injuries of the quadriceps and patellar tendons; injuries of the medial and lateral collateral ligaments; meniscal tears; effusions; degenerative changes; bursitis of the suprapatellar, prepatellar, infrapatellar, and pes anserine bursae; and other similar diseases. On the other hand, in the shoulder, ultrasound can be useful in the diagnosis of rotator cuff disease, biceps brachii injury, and acromioclavicular joint disease, among other shoulder pathologies.
Ultrasound is also a dynamic imaging modality that can highlight the movement of joints and muscles in real-time. Therefore, it can lead to the improved acquisition of exam skills when performed in conjunction with the specific maneuvers. For example, shoulder impingement syndrome can be better understood by learners of the physical exam by seeing the anatomy and dynamic movements under ultrasound.
Examination of the musculoskeletal system is a particularly difficult skill to acquire, involving the integration of the technical skills to perform specific maneuvers with the relevant clinical anatomy and physiology of joints. Overall, the integration of ultrasound with other clinical skills results in improved confidence and accuracy in the performance of the physical exam. In this video, we will demonstrate how to use POCUS to facilitate learning the examination of the knee and shoulder.
For most of the musculoskeletal examinations, the linear probe and a musculoskeletal preset should be selected. For the examination, the probe indicator is typically oriented proximally in the long axis. The short axis probe orientation is at the discretion of the person performing the exam, such that they understand what is anatomically left and right on the screen.
Bones, tendons, ligaments, and muscles are some of the common structures that are examined using ultrasound imaging. In an ultrasound image, bones appear as hyperechoic, and they create shadow artifact posteriorly. In addition to bones, tendons and ligaments also appear hyperechoic, and they have a fibrillar appearance. In contrast, muscles appear relatively hypoechoic and striated.
The examination of the knee has been discussed in the previous JoVE video "Knee Exam".
Learners often do not feel confident while examining the knee due to a lack of understanding of the anatomy. POCUS allows for correlation of the physical exam with the underlying structures of the knee, increasing learner confidence and understanding of the knee exam.
To begin, take the linear probe and apply the gel to it. Next, select the musculoskeletal preset available on the ultrasound screen. Now, ask the patient to lie in the supine position with their knee slightly flexed. With the probe indicator directed towards the head, place the probe on the anterior knee of the patient. Then, optimize the obtained ultrasound image using the depth and gain options.
Now, begin by identifying the fibrillar quadriceps tendon and patella, and the femur bone. In a healthy knee, a small amount of anechoic fluid may be present in the suprapatellar bursa, and on a physical exam, this area should be examined with inspection and palpation for effusions.
Next, slide the probe inferiorly over the patella and identify the patellar tendon with its insertion on the tibial tuberosity. This is the area to inspect and palpate to identify prepatellar and infrapatellar bursitis and Osgood Schlatter's disease.
Now, move the probe to the medial knee with the indicator pointing proximally. Identify the medial joint line, medial collateral ligament or MCL, and medial meniscus. Palpation of the medial joint line is important for meniscal tears and osteoarthritis, and applying varus and valgus strain helps identify MCL strain or tear.
Next, slide the transducer distally and rotate obliquely to find the insertion of sartorius, gracilis, and semitendinosis on the tibia, where the pes anserine bursa is located. In anserine bursitis, palpation over the anserine bursa elicits tenderness.
Move the probe to the lateral side of the knee with the probe indicator pointing proximally. Identify the lateral joint line, lateral femoral epicondyle, lateral collateral ligament or LCL, lateral meniscus, and the head of the fibula. Palpation of the lateral joint line is important for meniscal tears and osteoarthritis, and applying varus, and valgus strain helps identify LCL strain or tear.
Next, slide the probe distally and more anterior to identify Gerdy's tubercle and the iliotibial or IT band. Note that the IT band is running over the lateral femoral epicondyle when the knee is in full extension. This area can be examined to diagnose the IT band syndrome, including palpation of Gerdy's tubercle.
The examination of the shoulder has been discussed in the previous JoVE videos "Shoulder Exam I" and "Shoulder Exam II".
Learners often struggle to understand and remember the examination of the shoulder due to its complex anatomy and the large number of maneuvers associated with the shoulder exam. Ultrasound enables learners to effectively correlate the physical exam with the underlying anatomy.
First, take the linear probe and select the musculoskeletal preset on the ultrasound machine. Next, ask the patient to be in the seated position with their elbow flexed and hand supinated and resting on the thigh.
Now place the probe in a transverse plane over the anterior shoulder and then identify the long head of the biceps brachii tendon. Yergasun and Speed's tests are used to identify the pathology of the long head of the bicep tendon and cause pain in the area of the tendon.
After that, optimize the obtained image using the depth and gain function. To identify the anisotropy artifact, gently fan the probe and note the changes in the image.
Slide the probe medially while externally rotating the shoulder to identify the subscapularis tendon and muscle. Note the dynamic motion under ultrasound with the function of the muscle and physical exam testing by resisted internal rotation.
Next, slide the probe laterally while internally rotating the shoulder to identify the teres minor and infraspinatus tendon and muscle. Observe the dynamic motion under ultrasound with the function of the muscle and testing by resisted external rotation.
Now, rotate the probe, so the indicator is directed proximally and positioned over the lateral aspect of the shoulder. Then identify the acromion process and supraspinatus tendon in the image. Note the dynamic motion under ultrasound with the function of the muscle.
Additionally, observe the movement of the supraspinatus tendon under the acromion process with the abduction of the shoulder. In shoulder impingement syndrome, the pain is generated from the impingement of structures between the acromion process and the head of the humerus
Next, position the probe along the superior aspect of the clavicle and identify the acromioclavicular joint in the image. In patients with acromioclavicular arthritis, the bone spurs and the fluid accumulation appear near the acromioclavicular joint. On physical exam, the joint space is compressed using the cross-body adduction test, causing pain in the area of the AC joint.
