Description
【Purpose】First-time patellar dislocations occur more frequently in the adolescent population. Anatomical risk factors such as patella alta, trochlear dysplasia, tibial tuberosity lateralization, and ligamentous laxity can contribute to increased risk of injury. Although the reason for the predominant incidence of this injury in adolescents remains unknown, it may reflect the higher activity levels and risk exposure in the adolescent population. The objective of this study was to investigate the relationship between pre-operative physical activity status and anatomical factors in patients with patellar dislocation and lateral patellar instability.
【Methods】Patients who were diagnosed with recurrent patellar dislocation or lateral patellar instability and underwent medial patellofemoral ligament reconstruction were retrospectively analyzed. Based on physical activity status before the onset of symptom, patients were divided into three groups: competitive sports, recreational sports, and non-sports. Tegner activity scores were evaluated for each patient. Regarding imaging, trochlea depth (TD) and patellar height (Insall-Salvati ratio, ISR) were measured on pre-operative lateral X-ray; tibial tuberosity-trochlear groove (TT-TG) distance values were measured on preoperative CT. One-way analysis of variance (ANOVA) and post-hoc analysis was used to compare three groups.
【Results】Overall, 110 knees of 75 patients (18 males and 57 females; mean age, 20.4±10.0 years) were included in this study. There were 34 patients in the competitive sports group, 18 in the recreational sports group, and 23 in the non-sports group with significant different Tegner activity scores of 7.0, 3.9, and 2.8, respectively (p<0.001). The mean age of each group was 16±4.0 years, 14.6±2.0 years, and 30.4±11.1 years, respectively; the mean age of the non-sports group was significantly higher (p<0.01). The mean values of TD were 1.9±1.5 mm in the competitive group, 1.0±1.3 mm in the recreational group, and 1.2±1.3 mm in the non-sports group, with that of the competitive group being significant higher (p=0.011). There was no significant difference in ISR and TT-TG values among the three groups. There were significantly more cases of bilateral knee surgery in the competitive and non-sports groups (p=0.04).
【Conclusions】There were many cases of competitive athletes who underwent bilateral knee surgery at a young age despite higher TD, suggesting that higher physical activity may be associated with the early onset of symptoms, even if the femoral trochlea dysplasia was mild. These results may provide useful information when considering the diagnosis and surgical indication in young, active patients with lateral patellar instability.
