Among all the extensor mechanism pathologies, lateral patellar instability is of great interest not only for the knee specialist, but also for the general orthopedic surgeon and trainee. The procedure that is most frequently performed to treat lateral patellar instability is the medial patellofemoral ligament (MPFL) reconstruction. The reason for this great interest in this procedure is obvious. Medial patellofemoral ligament reconstruction is the most frequently performed procedure in the extensor mechanism. It also is the most predictable and has the best clinical results of all the procedures in the extensor mechanism. In this handbook we analyse the different reconstruction techniques, step by step, for the MPFL reconstruction, as well as other techniques less frequently used in the patient with lateral patellofemoral instability. We also analyse the treatment of medial patellofemoral instability. It is a very practical book, aimed at the general orthopedic surgeon and also the ones specialized in the knee.