Jordy van Sambeeck

Summary, general discussion and future perspectives 9 155 patient specific anatomic static and dynamic risk factors for recurrent patellar instability. Demographic risk factors that should be registered are age at first dislocation, sex, uni- or bilateral dislocations, Beighton score and BMI 10-13 . The anatomical and biomechanical risk factors should be mapped by a standardized protocol for physical exam, imaging techniques and radiologic measurements. A computational simulated adaption of patellofemoral anatomy and patellar tracking could then be made combining 4D CT and MR images. A validated model of this simulation could be developed in which the anatomy of a specific patient with patellar dislocation or maltracking can be altered to reconstruct the tracking of the patella to a patient specific optimal reconstruction. In this simulation the orthopaedic surgeon can adapt patellofemoral anatomy step by step. First, reconstruction of the MPFL is simulated leading to a new simulation of patellar tracking. Then, lateralization and patellar height can be adapted if necessary. Last, trochlear morphology can be adapted and consequently simulate the new patellar tracking pattern after a TTO and trochleoplasty. By this simulation, one can make an individualized surgical treatment plan including the decision if an osteotomy is indicated. Anatomic risk factors such as rotational deformities and coronal plane malalignment could be taken into account on indication by the surgeon as well as dynamic risk factors that have been assessed during physical exam. A tibial tubercle osteotomy could be indicated for persistent lateral tracking (medializing TTO) and/or late engagement of the patella in the trochlear groove (distalizing TTO) despite simulated MPFL-reconstruction. A trochleoplasty could be indicated for persistent lateral tracking or tracking over a trochlear bump despite MPFL-reconstruction and TTO. A deepening trochleoplasty is indicated in patients with a trochlear bump. A lateral facet elevating trochlear osteotomy could be indicated in patients with persistent lateral tracking without a bump but with a convex or short proximal trochlea. If an osteotomy is indicated, a proposed amount of correction of trochlear morphology, patellar height or lateralization can be given. Also at every step demographic and dynamic risk factors can be taken into account to decide whether to perform additional procedures or not. When demographic anddynamic risk factors predict worse outcome after isolatedMPFL-reconstruction a TTO can be indicated to increase chance of a good outcome when there is more lateralization or a higher patella than average, despite the threshold value which is normally used is not reached. Step by step the surgeon can build a final proposal for a treatment plan for an individual patient which can then be discussed, including management of expectations. Advances in imaging and more accurate preoperative planning could result in a patient specific treatment plan. Next, it is essential to be able to accurately verify the planned amount of correction intra-operatively. A prerequisite for accurate