Tibial tubercle torsion, a new factor of patellar instability.

INTRODUCTION: External torsion of the anterior tibial tubercle (TT), defined as external rotation around a craniocaudal axis with respect to the posterior femoral condylar plane, may induce patellar instability. To our knowledge no studies have focused on this parameter. The present study aimed to perform an MRI analysis of TT torsion. The study hypothesis was that TT torsion correlates with patellar instability and with 3 of its components: tibial tubercle-trochlear groove (TT-TG) distance, axial engagement index of the patella (AEI), and patellar tilt. MATERIAL AND METHODS: Four observers performed MRI measurements for 2 groups: 37 patellar instability patients (PI group) with history of at least 2 patellar dislocations, and 50 control patients with meniscal lesion but free from patellofemoral pathology. All measurements were taken from 2 axial slices with the posterior condylar plane as reference. RESULTS: The intra-class correlation coefficient (ICC) was 0.88. TT torsion correlated with patellar instability, with a mean 5.8̊ in controls and 17.9̊ in the PI group (P<0.001). There were also excellent correlations between TT torsion and TT-TG distance, patellar tilt and patellar lateralization (measured by AEI), with correlation coefficients greater than 0.85. DISCUSSION: TT torsion is a reproducible measurement, with excellent ICC. It is significantly correlated with patellar instability, with a discrimination threshold of 11.5̊, and correlations with all 3 components of instability. These statistical correlations enable TT torsion to be added to the list of patellar instability factors. Further studies should determine its biomechanical role and assess the contribution of associating TT derotation to medialization or distalization procedures. LEVEL OF EVIDENCE: III; case-control study.

C1-2 arthrography.

OBJECTIVE: To describe the technique of C1-2 arthrography and recommend it as a suitable treatment for pain due to C1-2 abnormalities. MATERIALS AND METHODS: One hundred patients with the following conditions were studied: cervical pain or neuralgia without radiographic changes (group 1, n = 23), osteoarthritis (group 2, n = 37), rheumatoid arthritis (group 3, n = 23), ankylosing spondylarthritis (group 4, n = 5) and diverse conditions (group 5, n = 12). The technique consists of lateral puncture of the posterior aspect of the C1-2 joint with a 20-gauge needle under fluoroscopic control, arthrography using 1 ml contrast medium, and a 1-ml long-acting steroid injection subsequently. RESULTS: The articular cavity has an anterior and a posterior recess. Sometimes the posterior recess is large. In 18% of cases the contralateral joint also opacifies. CONCLUSIONS: C1-2 arthrography appears to be an efficient and safe technique for the treatment of upper cervical pain due to C1-2 articular disorders.

[MRI of the knee. Value of delayed sequences after intravenous injection of gadolinium]. / IRM du genou. Intérêt de séquences retardées après injection intraveineuse de gadolinium.

A prospective study of delayed sequences after intravenous injection of gadolinium for knee MRI shows the similar results as from the literature: enhancement of synovial fluid after 30 minutes. Sixteen patients were studied mainly with gradient echo. This phenomenon improves the visualisation of the intraarticular structures like meniscus, cruciate ligaments, or cartilage. This study leads to use this technique in case of difficulties like postoperative intraarticular lesions.

Case report: clear cell adenocarcinoma of the vagina: MR features.

Clear cell adenocarcinoma (CCA) of the vagina and the cervix is a rare tumour. Since 1971 its increased incidence has been ascribed to intrauterine exposure to diethylstilboestrol (DES) and as a consequence the US Food and Drug Administration has banned the use of all DES-type medications during pregnancy. We report a case of CCA demonstrated by magnetic resonance imaging.

Synovial sarcomas of the head and neck: CT and MR findings.

The authors present three cases of histologically proved synovial sarcoma. CT is useful in assessing erosive or destructive changes in bone, and in demonstrating calcifications. MR characteristics are nonspecific; calcifications within these tumors can be missed on MR. MR can help to assess tumor extension, vascular invasion, and hemorrhage within the tumor.

[Aseptic osteonecrosis of the knee induced by corticoids. MRI aspects]. / Ostéonécroses aseptiques des genoux induites par les corticoïdes. Aspects IRM.

Authors report the results of a series of 29 knees examined by magnetic resonance imaging in 16 patients subjected to a long-term corticosteroid therapy (6 systemic lupus erythematosus and 10 kidney transplanted people). Abnormal signals of condyles or tibial plateaus were observed in 12 patients (19 knees). Lesions, which were asymptomatic in 37% of the cases studied, mostly showed (12/24 condyles) a fatty signal area marked out by a hypointense signal strip in T1 edged with a hyperintense signal in T2. Some developed lesions were hypointense whichever the sequence. Our study confirmed the frequency of the lateral condyle involvement (60%) and the bilateral aspect of the lesions (50%) in osteonecrosis of the condyles following the corticosteroid therapy. The associated lesions of articular surfaces (3 cases) could be well assessed through magnetic resonance imaging on T2 or T2* weighted images. In two cases, the abnormal signals of the condyles suggesting a medullary edema (hypointense signal in T1 and hyperintense signal in T2) spontaneously disappeared 6 and 9 months after their discovery. Abnormal signals related to medullary infarcts (10 knees) were always associated with abnormal condyles. Most time their aspect in magnetic resonance imaging, except old calcified lesions, was characteristic: serpiginous hypointense signal isolating areas of fatty signal edged with a hyperintense signal strip in T2. In risk patients, magnetic resonance imaging allows early detecting knee necroses, precising the extent of epiphyseal and metaphyso-diaphyseal lesions and their impact on articular surfaces.