Jordy van Sambeeck

General introduction 23 1 anteromedial tibial tubercle transfer by Fulkerson 26 (1990). In Nijmegen Koëter, Tigchelaar and Rood performed and published PhD work on patellofemoral disorders under supervision of promotor Van Kampen. Koëter concluded that operative intervention can be indicated for recurrent patellar instability and that surgical correction should be aimed at the anatomic abnormality. Tigchelaar provided an overview of the epidemiology and etiology of patellofemoral dysfunction and increased insight into diagnosis and evaluation. Rood showed the optimal conservative treatment and benefits of a dynamic MPFL-reconstruction. With an adequate MPFL-reconstruction technique as cornerstone of surgical treatment of patellofemoral instability, the question arises on the added value of osseous procedures in stabilizing the patella in patellofemoral surgery. The two types of osseous procedures that are frequently performed and address underlying anatomic abnormalities are the TTO and the trochleoplasty. This thesis aims to address some clinical questions relevant for the optimal surgical treatment, including these two osseous procedures, of patients with patellofemoral instability. The following research questions summarize the topics of this thesis: Imaging (Chapter 2) 1. What is the intra- and interrater reliability for different patellar height measurement methods on conventional radiography, CT and MRI? (Chapter 2) Patellar height is a well-known anatomic risk factor for recurrent patellar instability and one of the indications for TTO. Measurement of patellar height should be included in the diagnostic workup for treatment of patellar instability. Several measurement methods and imaging modalities are in use. It is still under debate which measurement method is most reliable and which cutoff value is considered abnormal on different imaging modalities. Chapter 2 determines the intra- and interrater reliability for five different patellar height measurements on three different imaging modalities (CR, CT, MRI). Tibial tubercle osteotomy (Chapter 3, 4) 2. What is the incidence of postoperative complications, specifically fracture and non- union, after a self-centering tibial tubercle osteotomy? (Chapter 3) 3. What is the incidence of postoperative complications, specifically fracture and non- union, after a V-shaped tibial tubercle osteotomy? (Chapter 4) Serious complications that are specifically related to an osteotomy include fracture and non-union. The short- and long-term results of the self-centering sliding tibial tubercle osteotomy (TTO) have been described previously. Good clinical results, low pain scores and a low amount of recurrent instability were demonstrated. In Chapter 3 we quantify the risk of procedure specific serious complications of the self-centering sliding TTO in a large case series including 529 procedures.