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FIGURE 4.17. Soft tissue injury in an elderly patient suspected of having a femoral neck fracture. (A) Coronal Tl-weighted image of both hips reveals no femoral neck fracture. (B) Coronal T2-

weighted fat-suppressed image demonstrates marked soft tissue edema or hemorrhage (arrow) and rupture of the left gluteus maximus muscle

FIGURE 4.17. Soft tissue injury in an elderly patient suspected of having a femoral neck fracture. (A) Coronal Tl-weighted image of both hips reveals no femoral neck fracture. (B) Coronal T2-

weighted fat-suppressed image demonstrates marked soft tissue edema or hemorrhage (arrow) and rupture of the left gluteus maximus muscle tissues.

23,24,64

MRI offers an excellent means of iden tifying, localizing, and determining the severity of muscle and tendon injuries about the hip. Injuries of the myotendinous unit typically occur at the myotendi-nous junction. On MRI, muscular injuries typically demonstrate increased signal within muscle fibers at the myotendinous junction on T2-weighted or STIR images, indicating intrasubstance hemorrhage or edema. Abnormally increased signal in the tendon on T2-weighted images, myofascial separation, muscle fiber retraction, or wavy-appearing tendon fibers are indicative of a more severe injury. A complete tear involves avulsion of the origin or insertion of the tendon (see Figure 4.16) or complete disruption of muscle fibers.

Stress Fractures

Stress fractures of the femoral neck and pelvis are a common cause of unexplained hip pain and are important to diagnose due to the risk for developing a complete fracture and potentially necessitating surgical intervention. Plain radiographs are typically normal in the early stage of femoral neck stress fractures. The earliest plain radiographic change in a femoral neck stress fracture is an indistinct linear area of sclerosis oriented perpendicular to the major trabeculae or new bone formation along the medial femoral neck. Both nuclear scintigraphy and MRI are more sensitive than plain radiographs in detecting early stress fractures. Bone scanning typically reveals increased activity at the site of the fracture because of increased bone turnover and increased flow. MRI, however, is preferable to nuclear scintigraphy as it typically yields a more specific diagnosis and better spatial resolution and allows simultaneous evaluation of the extraartic-ular soft tissues.30 Femoral neck stress fracture appears as a focal poorly defined area of abnormal signal along the medial femoral neck that is dark on T1-

weighted images and bright on T2-weighted or STIR sequences (Figure 4.18). In a study of patients with femoral neck stress fractures, resolution of marrow edema seen on MRI occurred by 6 months in 90% of patients.

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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