Glenohumeral joint instability is extremely common. With regard to primary anterior shoulder dislocations, the incidence is between 8.2 and 23.9 per 100 000 person-years, with an estimated prevalence of 1.7%. Many imaging methods, including arthrography, CT arthrography, MR arthrography, have been used to image the glenoid labrum and the associated structures of the capsular mechanism. The aim of the study is to prove MR arthrography is the preferred imaging technique for the investigation of patients with shoulder instability. MR arthrography reliably shows subtle lesions of the labroligamentous complex, providing information essential to the surgeon concerning the surgery or arthroscopic repair .Thirty Patients with clinically evident or suspected shoulder impingemint or glenohumeral instability.of both sexes were included , conventional MRI was performed for all patients followed by CT guided intraarticular contrast injection then MRI Arthrography images taken within thirty minutes. Data were collected, revised, coded and entered to the Statistical Package for Social Science (IBM SPSS) version 20.

Background: Patello-femoral stability is principally influenced by anatomic factors. Understanding the anatomy and biomechanics of the patello-femoral joint provides insight on the etiology and management of patellar instability. Magnetic resonance imaging (MRI) has emerged as an auxiliary method for investigating patello-femoral instability, particularly for detecting osteochondral lesions and for evaluating the medial patello-femoral ligament (MPFL). Objective: descriptive study including analysis of MRI knee done for patients with patellar instability suspected clinically with or without history of trauma. Patients and Methods: thirty patients were included in this study, all with suspicious patellar instability from Ain-Shams University, orthopedic clinic and other private clinics. A cross-sectional study was held where all the patients underwent MRI routine knee protocol. MRI knee images were interpreted for identification of different pathologies contributing to patellar instability. Results: sixty percent of the patients included in our study had MPFL injury, 43% showed patella alta, 83% showed trochlear dysplasia (by different measurements) and 43% showed lateral displacement of TT. Conclusion: MRI the modality of choice in diagnosing different pathologies of patellar instability, for its value in assessing soft tissue structures, detailed imaging of the cartilage and applying all measurement required.

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