MR imaging appearance of the extensor mechanism of the knee: functional anatomy and injury patterns.

Trauma to the extensor mechanism of the knee, a common clinical problem, can be accurately evaluated with magnetic resonance (MR) imaging. The extensor mechanism consists of the quadriceps muscle and tendon, patella, patellar tendon, and patellar retinacula. Injuries of these structures can be classified into partial and complete tears. Acute injuries are associated with edema, hemorrhage, and fluid collections; chronic injuries often demonstrate redundancy, atrophy, and retraction of the affected structures. MR imaging is useful in differentiating partial and complete tears and in evaluating tissue edema and hemorrhage. It also allows detection of unsuspected nondisplaced patellar fractures and chronic conditions due to repetitive trauma. Transient dislocation of the patella is an often clinically unsuspected entity for which MR imaging can serve an important diagnostic role. A detailed understanding of the functional and anatomic relationships of the extensor mechanism can greatly assist in interpretation of MR images of the traumatized knee.

Normal magnetic resonance imaging anatomy of the ankle and foot.

The normal anatomy of the ankle and fore-foot is quite complex and presents a challenge for both MR imaging and interpretation. Many of the critical ligaments and tendons require imaging in several planes for greatest diagnostic accuracy. We hope this article serves as a solid foundation and a reference for the excellent articles that follow.

Transient lateral patellar dislocation: diagnosis with MR imaging.

OBJECTIVE: Transient lateral patellar dislocation is frequently difficult to diagnose accurately on the basis of clinical findings. Accordingly, we studied the MR findings in 26 cases to determine if MR imaging is useful in establishing the diagnosis. MATERIALS AND METHODS: A retrospective review of 1450 MR examinations of acutely injured knees was performed to determine the MR findings resulting from transient lateral patellar dislocation. A distinctive constellation of MR findings reflecting the known mechanism of injury indicative of transient lateral patellar dislocation was found in 26 patients. Patellar dislocation was not clinically suspected before imaging in 19 (73%) of these 26 patients; most patients had been referred for suspected injury of the cruciate ligaments or menisci. Axial, sagittal, and coronal MR images were obtained in all patients, and all had clinical follow-up. Correlation of MR findings with surgical findings was possible in six. RESULTS: Specific components of the constellation of MR findings included disruption or sprain of the medial retinaculum in 25 (96%) of 26 patients, lateral patellar tilt or subluxation in 24 patients (92%), lateral femoral condyle contusion in 21 patients (81%), osteochondral injury in 15 patients (58%), and joint effusion in all 26 patients (100%). Concomitant injury to major ligaments or menisci was present in eight (31%). CONCLUSION: Our findings suggest that patients with transient lateral patellar subluxation have a distinctive constellation of MR findings that can be used to distinguish this entity from other common knee injuries.

Diverticulitis of the duodenum: clinical and radiological manifestations of seven cases.

Seven patients with duodenal diverticulitis were evaluated by computed tomography (CT) and various other abdominal imaging techniques. The series included four men and three women who ranged in age from 47 to 84 yr (mean: 65 yr). They had presented with epigastric or periumbilical pain, low-grade fever, leukocytosis, and loss of appetite and weight due to postprandial cramps or vomiting. In each instance, the abdominal CT examination proved crucial in the diagnosis of duodenal diverticulitis, with contained perforation or inflammatory changes involving the adjacent structures. Five patients underwent laparotomy while two others were treated conservatively with antibiotics and/or percutaneous drainage of peridiverticular abscess. The clinical and radiological features of this uncommon entity are herein described, along with a brief review of the medical literature regarding the current approach to its diagnosis and management.