Jordy van Sambeeck

Chapter 6 94 trochleoplasty were reviewed. They included 6 studies and a total of 186 knees, with and without concomitant stabilizing procedures. The mean follow-up was 44 months and 4 out of 6 studies had a follow up less than three years. The mean postoperative Kujala score ranged from 81.7 to 92.1 and the mean increase in Kujala score was 26.2 points. Few authors published results after a longer follow up 10, 22, 23 . Dejour et al. 23 reported a Kujala score of 81 at a mean follow-up of 66 months and Ntagiopoulos et al. 22 published a Kujala score of 87 at a mean of 7 years follow-up, both after a Dejour type trochleoplasty. Both these studies were also incorporated in the systematic review of Balcarek et al 5 . Von Knoch et al. reported a mean postoperative Kujala score of 95 in 45 knees after a Bereiter trochleoplasty at eight year follow-up 10 . In these series the authors described highly variable results, patellofemoral pain improved in 22 out of 45 knees postoperatively, but worsened in 15 out of 45 knees. Unfortunately we are not able to report a difference in pre- and post-operative Kujala scores as it was not recorded pre-operative, but the mean Kujala scores reported in other studies are higher than in our results. The reported recurrence of patellar instability in our study (table 3) is higher than reported in other studies. Beaufils et al published an overview of the incidence of recurrent dislocations after trochlear osteotomies 6 and reported a maximum of 10% (2 out of 20 patients) of persistent objective patellar instability in one study by Thaunat et al24 and 2% in two other studies25, 26. No persistent instability was reported in the other six studies4, 10, 11, 27-29 included in their overview. These results are confirmed by Balcarek et al who found recurrent instability in 4 out of 186 knees (2.1%) in their systematic review 5. However, most patients in these studies used additional procedures during the index procedure such as an MPFL-reconstruction, lateral release, medial reefing or tibial tuberosity transfers. In our study, no additional procedures were performed during the index surgery. Additional realignment procedures were performed in 7 out of 15 knees prior to surgery and in 3 knees at a later stage when there was persistent patellar instability. At latest follow up, 6 patients reported symptoms of patellar instability in 7 knees out of which 4 patients reported recurrent patella dislocations in 4 knees (Table 2). Given the results of our study and those mentioned above, we advise not to perform this trochlear osteotomy as a stand-alone procedure but to combine it with a medial soft tissue stabilizing technique such as an MPFL reconstruction. Pre-operatively, we observed no osteoarthritis in 14 out of 15 knees and at final followupwe observed radiological patellofemoral osteoarthritis Iwano grade 1 or 2 in 12 out of 15 knees21, and one patient underwent a patellofemoral arthroplasty. This is higher than the occurrence of osteoarthritis after conservative treatment for patellar instability, which has been reported to be 29% (6/21) classified by the Ahlbäck scale at 14 years follow up 30. Out of the few studies with a longer follow up, Von Knoch found a similar incidence of degenerative changes in the patellofemoral joint (73%, 24 out of 33 knees) at 8 years follow up after a Bereiter