الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Patellofemoral instability generally is defined as acute or chronic. Acute instability refers to a primary, traumatic episode in which the patella dislocates laterally, while chronic instability denotes recurrent dislocations. Medial dislocations are rare and are typically iatrogenic (6).A thorough history and a careful physical examination are essential to accurate diagnosis (78). Standard radiographic evaluation should be obtained in each patient with patellofemoral disorders. CT has been widely used to study the patellofemoral joint in the first 20 degrees of flexion, where it cannot be investigated using traditional radiographic techniques (187). The goal of any treatment should be to restore the normal anatomy of the joint. It is important to understand the basic anatomy and biomechanics of this condition, the classification of different types of patellar instability, varying presentations, and diagnostic techniques and criteria, including the types of imaging studies that can be useful in determining the ultimate course of treatment (199). Generally, three categories of operations prevail, proximal realignment, distal realignment and procedures where no alteration in the alignment of the extensor mechanism is contemplated. Proximal (open or arthroscopic), medial plication, vastus medialis obliqus advancement and medial patellofemoral ligament repair or reconstruction. Distal realignment procedures include medial transfer of the patellar tendon, anterior displacement of the tibial tuberosity, anteromedial displacement of the tibial tuberosity, semitendenious transfer, and osteotomies of the tibial tuberosity, procedures which do not alterate the alignment of the extensor mechanism as arthroscopic synovectomy and debridement, patellectomy and prosthetic resurfacing of the patella (127). Operative morbidity with open procedures may be avoided with an arthroscopic approach that limits violation of the extensor mechanism and reduce postoperative pain and stiffness (200).