Avulsion injuries are common among participants in organized sports, especially among adolescent participants. Imaging features of both acute and chronic avulsion injuries of the pelvis, knee, ankle and foot, shoulder, and elbow were evaluated to help distinguish these injuries from more serious disease processes such as neoplasm and infection. At radiography, acute injuries (ie, those resulting from extreme, unbalanced, often eccentric muscular contractions) may be associated with avulsed bone fragments, whereas subacute injuries have an aggressive appearance that may include areas of mixed lysis and sclerosis. Chronic injuries (ie, those resulting from repetitive microtrauma or overuse) or old inactive injuries may be associated with a protuberant mass of bone and may bear a striking resemblance to a neoplastic or infectious process. Although not usually required, computed tomography is helpful in the diagnosis if radiographic findings are equivocal or if the injury is not in the acute phase. MR imaging is best suited for the evaluation of injuries to muscles, tendons, and ligaments. Recognition of characteristic imaging features and familiarity with musculotendinous anatomy will aid in accurate diagnosis of avulsion injuries.

Although skeletal muscle is the single largest tissue in the body, there is little written about it in the radiologic literature. Indirect muscle injuries, also called strains or tears, are common in athletics, and knowing the morphology and physiology of the muscle-tendon unit is the key to the understanding of these injuries. Eccentric muscle activation produces more tension within the muscle than when it is activated concentrically, making it more susceptible to tearing. Injuries involving the muscle belly tend to occur near the myotendinous junction. In adolescents, the weakest link in the muscle-tendon-bone complex is the apophysis. Traditionally, plain radiography has been the main diagnostic modality for evaluation of these injuries; however, with the advent of MRI it has become much easier to diagnose injuries primarily affecting the soft tissues. This article reviews the anatomy and physiology of the muscle-tendon unit as they relate to indirect muscle injuries. Examples of common muscle injuries are illustrated.

Diagnosis of osteomyelitis of the foot in diabetic patientsmay be difficuft because of the coexistence of chronic cellulitis, vascular insuffIciency, and peripheral neuropathy. This study compared the diagnostic accuracies of plain films, bone scans, and MR imaging studies in diabetic patients with suspicion of osteomyelftis of the foot Twentynine plain radiographs, 20 bone scans, and 30 MR studies were obtained in 24 patients.

Familiarity with the variable appearance of hamstring injuries over time and with different modalities facilitates accurate characterization.

MR imaging enabled detection of peroneus brevis and peroneus longus tendon tears.