Abstract

RIBEIRO, Maria Margarida; NOGUEIRA, Fábio; SARDINHA, José  and  JONES, José Henrique. Critérios imagiológicos da instabilidade femoro-patelar por ressonância magnética. Rev. Port. Ortop. Traum. [online]. 2012, vol.20, n.4, pp.425-435. ISSN 1646-2122.

Objectives: This study aimed to evaluate the relevance of magnetic resonance imaging (MRI) of the knee to determine indicators of patellofemoral instability. Materials and Methods: The sample consisted in 200 measurements performed in images from 50 patients. Concerning the clinical indication only 4 patients reported problems in the extensor system or patellar cartilage. The images included in the sample were measured by two independent observers. In the measurement procedures were used images in T2*TRS WFS and PD SAG sequences. The parameters calculated were the Insall & Salvatti Index (ISI), angle of the trochlear groove, patellar tilt and displacement of the patella. Results: In 49 cases the ISI values obtained suggested being normal for the position of the patella (≤ 1.3 cm). The values for inclination patella’s angle indicated an external predisposition factor for trochlear dysplasia in 17 of 50 cases with opening and internal angles and tilt (≥ 11O). The angle of the trochlear groove is dysplastic in 24% of the sample with values > 150O. For the external displacement indicator, it was found that 39% of the cases the distance was negative above -20 mm (external displacement). Conclusions: It is possible, without additional costs, to develop an algorithm to determine the reference values to be used, for screening of instability of the patella from an MRI examination of the knee, even if the referral clinic admits different pathology. The MR open field or cylindrical type may be an efficacy method of screening for this pathology.

Keywords : Magnetic resonance imaging; patellofemoral instability; measurement indicators.

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