PURPOSE OF THE STUDY Patellar dislocation is a fairly frequent knee joint injury in young patients. In most cases, this injury can be treated conservatively or surgically. In many cases, patellar cartilage or lateral femoral condyle or both these parts of articular surface are injured, and in conservative treatment this chondral damage very often remains undiagnosed. The purpose of this study is to evaluate the outcomes of treatment in patients who underwent surgery for patellar dislocation and in whom extensive traumatic cartilage lesions of the patella were found. MATERIAL AND METHODS The authors carry out a retrospective evaluation of outcomes in 34 patients from the period 2005-2014, in whom extensive chondral defect of the posterior side of the patella after its traumatic dislocation with the mean size of 4.1 cm2 (the maximum size was 28x18 mm) was found, namely in 21 women and 13 men aged 13-28 years. The patients were indicated for arthroscopic surgery based on the clinical examination which revealed a clear traumatic patellar dislocation. In 2 radiographs only, an osteochondral fragment was found, and in these patients a CT scan of the injured knee was made. The patients were retrospectively broken down into 3 sub-groups by the method of treatment of the chondral defect. The mean size of the defect in the debridement group was 2.7 cm2 compared to 4.6 cm2 in the group with cartilage fixation. In group I reinsertion through MiniSynthes 2.0 screws (5 patients) was performed, in group II reinsertion of the chondral fragment was done using transosseous PDS sutures (19 patients), in group III debridement of injured cartilage was carried out (10 patients). RESULTS The patients were assessed postoperatively using Kujala score and IKDC score. The mean age of patients at the time of injury was 19.6 years, with mean follow-up of 30.2 months. No group reported limitations of range of motion at the time of evaluation. Knee pain under load was present in 3 patients in group I, in 1 patient in group II and in 7 patients in group III. No patient suffered from another patellar dislocation. The mean Kujala score was 84.7 (group I), 89.3 (group II), and 78.5 (group III). The IKDC was 84.6 in group I, 87.2 in group II, and 74.3 in group III. At the time of evaluation, pre-injury activities were resumed by 72% of patients from group I, 82% of patients from group II, and 69% of patients from group III. DISCUSSION Treatment of primary patellar dislocation is still subject to discussions on whether to pursue conservative or surgical treatment. The main topic of studies is the subsequent rate of patellar re-dislocation and the rate of cartilage damage in patellofemoral joint, examined is also the scope of performed surgery, while only very few papers focus on treating the injured cartilage of the patella. Despite numerous studies, the optimal method of treatment of this injury has been identified as yet. CONCLUSIONS Where a serious, extensive fragment of patellar cartilage is found, the fixation of cartilage with the use of transosseous PDS sutures brings very good and good results, without the necessity of another surgery, while the simultaneous treatment of medial patellar retinacula considerably decreases the risk of patellar re-dislocation, thus reducing the risk of further damage to cartilage of patelofemoral joint. The use of transosseous suture fixation is considered by the authors to be more appropriate than the use of screws, mostly because no further surgery to remove fixation screws is necessary. Key words: acute patellar dislocations, chondral lesions, chondral repair, arthroscopy.

Klinika traumatologie Lékařské fakulty Masarykovy Univerzity Brno