Jordy van Sambeeck

Complications of a self-centering sliding tibial tubercle osteotomy for patellofemoral complaints 3 47 Introduction A tibial tubercle osteotomy (TTO) is used to correct patella alta or an increased tibial tubercle trochlear groove distance (TT-TG) in young patients with severe patellofemoral complaints.Withadistalizationormedializationof the tibial tubercle the anatomical abnormalities can be addressed. This increases patellofemoral stability and decreases abnormal patellofemoral contact pressures 1 . Different techniques for TTO have been described. Frequently used current methods are the modified Elmslie-Trillat medialization technique 2 , the Fulkerson anteromedialization technique 3 and techniques in which the tibial tuberosity is completely detached. The recent review by Payne et al. 4 concluded that the risk of complications is related to the employed technique. In his review some techniques had a complication rate as high as 10.7%, whereas others had lower complications rate of 3.3%. Previously, the short- and long-term results of a self-centering technique were published 5, 6 . We perform a lateral osteotomy in the frontal plane to guarantee that there is no anterior or posterior displacement. After temporarily distal fixation with an AO 2.5 mm drill bit, the tibial tubercle will centralize to its neutral position in 90 degrees of flexion of the knee. Authors demonstrated good clinical results, low pain scores and a low amount of recurrent instability and only marginal increase of radiological signs for patellofemoral osteoarthritis at ten years after this procedure 6 . Altogether, the previous literature indicates that there is a serious risk of either early or late complications after TTO. However, most previous studies are based on small case series, which might lead to false conclusions, because observations can be due to chance. The largest cohort is described by Cox et al. and included 116 procedures in 104 patients 2 , other series ranged from 18 to 62 patients 4 . The purpose of this large case series is to quantify the risk of procedure specific postoperative complications related to a uniform self-centering TTO technique performed by two different surgeons in one center. We hypothesize that non- union or fracture occurs in less than 1% of the procedures. Patients and methods All patients who underwent either an isolated self-centering sliding TTO or a TTO procedure combined with a medial patellofemoral ligament reconstruction (MPFL) and/or a trochlear osteotomy between May 2008 and November 2016 with at least one year of follow up were included. Indications for TTO were recurrent patellar dislocations or instability, persistent patellofemoral pain with anatomic abnormalities or post traumatic patella abnormality (patella alta after ruptured patellar tendon, patella baja after an anterior cruciate ligament reconstruction). All patients had closed epiphyseal growth plates. Data on complications was collected prospectively, all patient charts were retrospectively reviewed to check for completeness. Patients who were treated for patellar instability after a prior