The correlation between medial plica and trochlear dysplasis: An MRI study

BACKGROUND: Trochlear dysplasia is the most commonly encountered congenital etiologic factor of anterior knee pain. AIMS: The purpose of this study was to evaluate the relationship between trochlear dysplasia with medial patellar plica as well as to investigate the distribution of plica types according to types of dysplasia. SETTINGS AND DESIGN: This is a retrospective case-control study. MATERIALS AND METHODS: This study was conducted among 138 knee magnetic resonance imaging (MRI) scans. The presence of medial plica and its types were compared among 69 patients in whom trochlear dysplasia had been detected and 69 individuals with normal trochlear who were of the same age and gender as the patient group. STATISTICAL ANALYSIS: Trochlear dysplasia and medial plica was compared by Chi-square with Yates correction and Fisher's exact probability tests (P < 0.001). The data were presented as mean, standard deviation, minimum–maximum, frequency, and percentage. RESULTS: Of all the patients (n = 138), the number of patients in whom plica was observed was n = 104 (75.3%), and the distribution of plica type was as follows: n = 70 (67.3%) Type 1, n = 25 (24%) Type 2, and n = 9 (8.6%) Type 3. Medial plica was more frequently observed in patients with trochlear dysplasia (P < 0.001). Type 2 and Type 3 medial plica were more frequently encountered in trochlear dysplasia (P < 0.001). Type 3 plica was not seen in patients with normal trochlea. CONCLUSION: Medial patellar plica is more frequently seen in trochlear dysplasia. As the type of trochlear dysplasia progresses, the prevalence of thicker and shelf-shaped plica increases.