Jordy van Sambeeck

Summary, general discussion and future perspectives 9 153 In Chapter 8 the Banff Patellar Instability Instrument (BPII) and Norwich Patellar Instability score (NPI) were translated and validated in Dutch to fill in the lack of Dutch PROMs on patellofemoral disorders. These are two patient reported outcome measurements (PROMs) specifically designed for patients with patellofemoral disorders. The translation of the scores followed theMAPI method 9 . Clarity, understandability and acceptability was evaluated in a pilot series of 15 patients. Ninety-seven patients that had been surgically treated for patellofemoral instability completed all questionnaires. The internal consistency of the BPII and the NPI was excellent. Both scores demonstrated good reliability. The results of this study indicate that the Dutch version of the BPII and the NPI can be used for patients with patellofemoral instability. Treatment of patients with patellofemoral instability aims to improve patellar tracking leading to a stable patella that does not dislocate and with that to decrease functional impairment and pain due to patellar instability. The outcome of treatment can be objectified by recurrence of patellar dislocation. This outcome parameter is often described in studies reporting on conservative and/ or surgical treatment of patients with patellofemoral instability. However, it is clear that focusing on these ‘objective’ outcomes neglects the ‘subjective’ outcome experienced by the patient. This subjective outcome can be measured by valid and reliable disease specific patient reported outcome measurements (PROMS). The translation and validation of the PROMs which are specifically designed for patients with patellofemoral instability can be a starting point to get a better view on ‘subjective’ outcome and the correlation with the ‘objective’ outcome. We advise that they should be included in the routine measurement of outcome of treatment of patients with patellofemoral instability. The indication for surgical treatment of patellofemoral instability is often a combination of objective characteristics and subjective complaints. So far, most of the studies on patients with patellofemoral instability have used objective outcomes or general PROMs that might not be reliable measurements because patients are asked about general knee complaints and not specifically patellofemoral complaints. Consequently, these scores underestimate the impact of patellofemoral instability complaints on daily life of patients. Better understanding the perceived disability, can help to decide whether surgical treatment is indicated in an individual patient and can be used to predict outcomes for better management of patient expectations. Future perspectives In the introduction and general discussion of this thesis, we described the multifactorial character of treatment of patients with patellofemoral instability. Current imaging techniques and measurements, treatment algorithms and outcome measurements are under continuous development. It is therefore a very