OBJECTIVES

1. Describe the “special” radiographic views of the shoulder and knee and apply their uses.
2. Explain bony and soft tissue injury patterns associated with shoulder dislocations, and the imaging needed for each.
3. Discuss the appearance of rotator cuff tendinopathy, partial-thickness tears, and full-thickness tears on MRI and the views needed for diagnosis.
4. Understand the appearance of ACL tears, meniscus tears, and chondral damage on knee MRI.

ABSTRACT

Sports injuries are common in active individuals, regardless of professional level. The goal of both the clinician and the patient after the injury is to return to activity as quickly as possible. In order to achieve this goal, a correct diagnosis must be made. Imaging not only confirms or refutes a clinical diagnosis, it plays a critical role in guiding the treatment plan. Knowledge of the relevant anatomy is essential for optimization and interpretation of imaging. Additionally, it is helpful to know which imaging modalities are best for each specific injury. To obtain optimal images, sufficient knowledge of the pertinent anatomy and familiarity with injury patterns is necessary. This activity discusses the role of imaging modalities for common acute injury pathology of the shoulder and knee joints. Conventional radiography can be useful in injuries such as clavicle fractures, acromioclavicular joint injuries, Little League shoulder, and shoulder dislocations. Because magnetic resonance imaging is more sensitive for soft tissue injuries, it should be utilized for rotator cuff tears, meniscal tears, osteochondral fractures, and anterior and posterior cruciate ligament injuries. Magnetic resonance arthrogram provides sensitivity for intraarticular pathology, such as glenohumeral labral tears and meniscus tears in postoperative knees. Imaging of patellar dislocations and knee osteoarthritis are also discussed.

Introduction

Sports injuries are common in active individuals, regardless of professional level. The goal of both the clinician and the patient after the injury is to return to activity as quickly as possible. In order to achieve this goal, a correct diagnosis must be made. Imaging not only confirms or refutes a clinical diagnosis, it plays a critical role in guiding the treatment plan. It cannot be emphasized enough that knowledge of the relevant anatomy is essential for optimization and interpretation of imaging. Although anatomy will not be described in detail in this course, it behooves the reader to become familiar with the anatomy before attempting to understand the role of imaging in musculoskeletal injuries. For purposes of this discussion, the basic anatomy of the shoulder and knee joints are shown in Figures 1 and 2.^1,2 This activity will focus on the role of imaging modalities for common acute injury pathology of the shoulder and knee joints. It should be noted that most institutions have their own imaging protocols for joint injuries, and these may vary greatly. Various special views and traditional views of radiographs are commonly utilized for shoulder and knee injuries, and magnetic resonance imaging (MRI) betters our understanding of soft tissue injury. Generally speaking, it is best to use a dedicated joint coil, a small field of view, and slice thickness of 2 to 3 mm. Every precaution should be taken to minimize movement when possible.³