Chapter 21: Musculoskeletal

INTRODUCTION

Patients presenting to the emergency department (ED) or other acute care setting with a musculoskeletal complaint may represent a diagnostic challenge for the clinician. The first reported study of ultrasound in the evaluation of the musculoskeletal system was by Dussik and colleagues in 1958.¹ In this study, the authors were able to measure and describe the acoustic attenuation of articular and periarticular tissues, and this marked the starting point of musculoskeletal ultrasound.¹ Ultrasound has a distinctive ability to accurately visualize the soft tissue and musculoskeletal layers; this, coupled with significant advances in ultrasound technology, makes it more widely available at the point of care.

CLINICAL CONSIDERATIONS

Smaller, more portable ultrasound units, high-frequency small parts transducers with resolutions to a fraction of a millimeter, tissue harmonics, compound imaging technology, and extended-field-of-view features have helped promote ultrasound as a diagnostic tool for evaluating musculotendinous complaints by radiologists, orthopedists, rheumatologists, and emergency physicians. While magnetic resonance imaging (MRI) is often referred to as being the gold standard for musculoskeletal imaging, it is not an imaging modality that is readily available in the acute care setting. In addition, it requires that the patient has no absolute contraindication to MRI.

Ultrasound has emerged as a powerful extension of the physical examination, especially in the setting of a musculotendinous complaint.² When compared to other imaging modalities, such as plain radiography, computed tomography (CT), and MRI, ultrasound has numerous advantages. Imaging of tendons, joints, and muscles at the point of care can help the provider rapidly make a correct diagnosis for a host of painful musculoskeletal conditions and allow for optimal patient management. In addition, ultrasound can be used at the point of care to guide musculoskeletal procedures and provide dynamic evaluation of musculoskeletal complaints.

Self-teaching programs in musculoskeletal ultrasound have been promulgated for rheumatologists with excellent results reported after 24 hours of active scanning and 8–9 hours reviewing images with tutors.³ A similar self-teaching program has been incorporated into the educational curriculum at a residency program in Physical Medicine and Rehabilitation.⁴ While ultrasound provides numerous advantages, it is highly operator dependent. Musculoskeletal ultrasound examinations can be challenging due to complex anatomical, physiologic, and technical issues related to image optimization and artifacts.⁵ Therefore, while a myriad of musculoskeletal applications for diagnostic ultrasound have been described in the ultrasound literature, some of these applications require expertise in ultrasound beyond that of most point-of-care ultrasound (POCUS) operators and will not be discussed in this chapter.

CLINICAL INDICATIONS

Possible indications for ultrasound examination of the musculoskeletal system in the emergency and acute care setting are as follows:

• Musculotendinous trauma

• Musculotendinous infection/inflammation

• Swollen joint evaluation/Arthrocentesis

• Osseous trauma

• Osseous infection

• Musculotendinous aspiration or injection procedure guidance

MUSCULOTENDINOUS TRAUMA

Trauma to the musculoskeletal system is ...