Evaluation of posterior tibial pathology: comparison of sonography and MR imaging.

OBJECTIVE: To compare the results of sonographic (US) and magnetic resonance (MR) imaging in detecting pathology of the posterior tibial tendon (PTT) in patients with PTT dysfunction. DESIGN: Twenty-two ankles that were clinically suspected by the orthopedic surgeon to have PTT dysfunction were evaluated with US (10 MHz linear-array transducer) and 1.5 T MR examinations within the same day. The US and MR studies were conducted and interpreted by two sonologists and two musculoskeletal radiologists who were masked to the results of the other study. Four patients had bilateral studies. Classic clinical findings were utilized as a standard reference in staging PTT dysfunction. PATIENTS: Eighteen women (mean age 61 years, age range 39-86 years). RESULTS: Based on a commonly accepted staging system for PTT dysfunction, 6 ankles were classified as stage I, 11 ankles as stage II, and 5 ankles as stage III. All stage I ankles were interpreted as having an intact PTT by both MR imaging and US. In the stage II and III tendons, MR imaging demonstrated PTT tears in 12 of 22 examinations, including 11 partial tears and 1 complete tear. US demonstrated PTT tears in 8 of 22 examinations, including 8 partial tears and no complete tears. The findings of US and MR imaging were consistent in 17 of 22 cases (77%). The five inconsistencies were as follows: in 4 cases, US reported tendinosis when MR imaging interpreted partial tears (no change in management); in one case, US diagnosed a partial tear when MR reported a complete tear of the PTT (no change in management because the clinical findings were more consistent with a partial tear). CONCLUSIONS: In this study, US and MR imaging of the PTT were concordant in the majority of cases. US was slightly less sensitive than MR imaging for PTT pathology, but these discrepancies did not affect clinical management.

MRI findings of septic arthritis and associated osteomyelitis in adults.

OBJECTIVE: The purpose of this study was to describe the soft-tissue, synovial, and osseous MRI findings of septic arthritis. MATERIALS AND METHODS: At 1.5 T (T1-weighted, T2-weighted or STIR, and contrast-enhanced images), 50 consecutive cases of septic arthritis were evaluated by two observers for synovial enhancement, perisynovial edema, joint effusion, fluid outpouching, fluid enhancement, and synovial thickening. The marrow was assessed for abnormal signal on T1- and T2-weighted images or after contrast enhancement. We noted whether the marrow signal was diffuse or abnormal in bare areas. MRI findings were compared with microbiologic, clinical, and surgical data and diagnoses. RESULTS: The frequency of MRI findings in septic joints was as follows: synovial enhancement (98%), perisynovial edema (84%), joint effusions (70%), fluid outpouching (53%), fluid enhancement (30%), and synovial thickening (22%). The marrow showed bare area changes (86%), abnormal T2 signal (84%), abnormal gadolinium enhancement (81%), and abnormal T1 signal (66%). Associated osteomyelitis more often showed T1 signal abnormalities and was diffuse. CONCLUSION: Synovial enhancement, perisynovial edema, and joint effusion had the highest correlation with the clinical diagnosis of a septic joint. However, almost a third of patients with septic arthritis lacked an effusion. Abnormal marrow signal-particularly if it was diffuse and seen on T1-weighted images-had the highest association with concomitant osteomyelitis.

MRI findings associated with distal tibiofibular syndesmosis injury.

OBJECTIVE: Our objective was to describe the MRI findings associated with acute and chronic distal tibiofibular syndesmosis injury. MATERIALS AND METHODS: Ninety-four 1.5-T MRIs of ankles of 90 individuals with histories of severe sprain were assessed by two musculoskeletal radiologists for syndesmosis injury (acute, edema of the syndesmosis; chronic, disruption or thickening of the syndesmosis without edema). We examined associated MRI findings, including anterior talofibular ligament injury (scar, chronic injury; edema, acute injury), bone bruise, osteochondral lesion, tibiofibular joint congruity, tibiofibular recess height, and osteoarthritis. The Fisher's exact test and analysis of variance test were used to evaluate the significance of the associations. RESULTS: In 94 ankles, syndesmosis injury was seen in 63% (n = 59; 23 acute; 36 chronic). Anterior talofibular ligament injury (acute or chronic) was seen on MRIs in 74% (n = 70; 49 with syndesmosis injury; 21 without; p = 0.03). Bone bruises were present in 24% (n = 23; 18/23 acute; 4/36 chronic; 4/35 no injury; p < 0.0001). Of these, talar dome osteochondral lesions were present in 28% (n = 26; 11/23 acute; 14/36 chronic; 1/35 no injury; p = 0.0001; 13 medial; 13 lateral). The tibiofibular joint was incongruent in 33% (n = 31; 6/23 acute; 21/36 chronic; 4/35 no injury; p < 0.0001). The tibiofibular recess (mean +/- SD) was 1.2 +/- 0.92 cm in acute cases, 1.4 +/- 0.57 cm in chronic cases, and 0.54 +/- 0.68 cm in cases with no syndesmosis injury (p < 0.0001). Osteoarthritis was present in 10% (n = 9; 1/23 acute; 7/36 chronic; 1/35 no injury; p = 0.06). CONCLUSION: Injury to the distal tibiofibular syndesmosis has a significant association with a number of secondary findings on MRI, including anterior talofibular ligament injury, bone bruises, osteochondral lesions, tibiofibular joint congruity, and height of the tibiofibular recess.

MR imaging of anterior cruciate ligament tears: is there a gender gap?

OBJECTIVE: Clinically, females receive anterior cruciate ligament (ACL) tears more commonly than males. We explored whether gender differences exist in MR imaging patterns of ACL tears. DESIGN AND PATIENTS: At 1.5 T, two observers evaluated MR examinations of 84 consecutive age-matched patients (42 males, 42 females, aged 16-39) with ACL tears, for mechanism of injury, extent and type of tear, the presence of secondary signs and associated osseous, meniscal and ligamentous injuries. RESULTS: The most common mechanism of injury for both females and males was the pivot shift mechanism (67 and 60%, respectively). Females were more commonly imaged in the acute stage of tear than males (98 and 67%, respectively, p=0.001) and more commonly possessed the typical posterolateral tibial bone contusion pattern (88 and 62%, respectively, p=0.0131). Males exhibited a deeper femoral notch sign (2.7 and 2.0 mm, p=0.007) and medial meniscal, lateral collateral ligament and posterior cruciate ligament injuries more commonly than females (48 and 24%, p=0.009, 30 and 7%, p=0.035, 17 and 0%, p=0.035). There was no significant difference between genders for the presence of other secondary signs and contusion patterns, associated lateral meniscal tears, presence of O'Donoghue's triad or associated medial collateral ligament injuries. CONCLUSION: Gender differences in MR imaging patterns of ACL tears exist: females are more commonly imaged in the acute stage and more commonly possess posterolateral tibial bone contusions; males have a more severe presentation than females, associated with more severe lateral femoral condyle and soft tissue injuries.