Methods: We compared 361 treated cases of aneurysm occlusion after subarachnoid hemorrhage from 1997 to 2003 with 281 cases from 2006 to 2014. 2. Part of The anatomy of the medial patellofemoral ligament. Am J Sports Med 28:472479, Lewallen L, McIntosh A, Dahm D (2015) First-time patellofemoral dislocation: risk factors for recurrent instability. The ratio of the medial to the lateral facet length defines trochlear facet asymmetry (MT/LT) *100%. Predisposing factors to patellofemoral dislocation include patella alta, excessive lateral distance between the tibial tubercle and trochlear groove and a congenitally shallow trochlear groove5, any of which significantly increase a patients likelihood for dislocation. TT-TG is a reflection of the clinically measured Q angle. One of the more common MPFL reconstruction procedures uses a single hamstring tendon graft passed through the medial intermuscular septum at the adductor magnus insertion fixed by an anchor in the femoral condyle and sutured or anchored to the superomedial pole of the patella11. Kirsch M, Fitzgerald S, Friedman H, Rogers L. Transient Lateral Patellar Dislocation: Diagnosis with MR Imaging. Features that may predispose to patellar dislocation and/or patellar maltracking and can be evaluated with CT include patellar and trochlear morphology and the alignment between the two structures. Recent literature does not encourage the use of lateral release, since this can increase patellar instability. Fluid extending into the VMO myotendinous junction is generally seen in the setting of coexisting MPFL/retinacular tears. Initial diagnosis is key to a successful outcome, as these injuries are easily overlooked on plain radiographs with poor results well documented from delayed management. Google Scholar, Miller TT, Staron RB, Feldman F (1996) Patellar height on sagittal MR imaging of the knee. Knee Surg Sports Traumatol Arthrosc 22:23882395, Escala JS, Mellado JM, Olona M, Gin J, Sauri A, Neyret P (2006) Objective patellar instability: MR-based quantitative assessment of potentially associated anatomical features. Eur J Trauma Emerg Surg. Elsevier, Philadelphia, Buckens CF, Saris DB (2010) Reconstruction of the medial patellofemoral ligament for treatment of patellofemoral instability: a systematic review. Orthopedic Surgery 22 years experience. The goal of patellar instability treatment is to achieve a stable, functional, and pain-free knee and ultimately to halt or slow the development of osteoarthritis. The patella becomes unstable and undergoes a transient, violent lateral displacement. The convex articular surface of the patella places it at risk for chondral injury in either the dislocation or the reduction phases of injury. Patella instability in children and adolescents. Patellar tracking refers to the dynamic relationship between the patella and trochlea during knee motion [1].