BACKGROUND: The aim of this study was to analyse the biomechanical role of medial retinaculum, as a stabilising factor against lateral patellar dislocation.MATERIALS AND METHODS: This cadaveric-biomechanical study included the patellae of ten cadaveric knees, which were surgically exposed and the medial retinaculum of each one was located. A stable 24.51N force was applied to the four parts of the quadriceps, and an increasing lateral displacing force was applied to the patella, up to 5mm dislocation. The study was repeated for 0⁰, 45⁰, and 900 of knee flexion, with the medial retinaculum intact and dissected. The Wilcoxon signed rank test was used for data analysis. A p value <0.05 was considered as statistical significant.RESULTS: After the dissection of medial retinaculum, the lateral displacement force was lower at every angle of knee flexion (p=0.005, p=0.007, p=0.005 respectively). The lateral displacement force increased as the flexion angle increased (p=0.005), regardless of medial retinaculum integrity.CONCLUSIONS: Medial retinaculum acts as a stabilising factor for the patella, against its lateral dislocation in lower flexion angles. Therefore, methods of surgical reinforcement or repair of medial retinaculum could provide protection against recurrent patellar dislocation.