Objective To compare the differences in patellar morphological type distribution between patients with acute lateral patellar dislocation (LPD) and healthy individuals, and to analyze its correlation with gender and anatomical parameters of the patellofemoral joint. Methods The MRI data of 71 patients diagnosed with acute LPD from January 2023 to November 2025 Shandong Provincial Corps Hospital of Chinese People’s Armed Police Force were retrospectively analyzed and 100 healthy individuals were randomly selected. The distribution of patellar morphology types between the two groups was compared, and the correlation between the patient’s gender, patellofemoral joint anatomic parameters (patellar position, tibial tuberosity-trochlear groove (TT-TG) distance, and patellar trochlear type) and patellar morphology were analyzed. Results In the LPD group (30 males /41 females), there were 3 cases of Wiberg type I, 35 cases of type Ⅱ, and 33 cases of type Ⅲ. In the control group (57 males/43 females), there were 9 cases of type I, 85 cases of type II, and 6 cases of type Ⅲ. There was significant difference in the distribution of patella morphology between the two groups (P<0.05). Subgroup analyses in the LPD group revealed: significant difference in patellar type distribution between the normal patellar position group (24 type Ⅱ /13 type Ⅲ) and the high postion group (11 type Ⅱ /20 type Ⅲ) (P=0.016); no statistically significant difference between the normal TT-TG distance group (28 type Ⅱ/21 type Ⅲ) and the elevated TT-TG distance group (7 type Ⅱ/12 type Ⅲ); statistically significant differences in type distribution among the normal trochlea group (15 type Ⅱ/3 type Ⅲ), low-grade trochlear dysplasia group (15 type Ⅱ/13 type Ⅲ), and high-grade trochlear dysplasia group (5 type Ⅱ/17 type Ⅲ) (P=0.001). Significant differences were observed between the high-grade trochlear dysplasia group and the normal group, the high-grade trochlear dysplasia group and the low-grade trochlear dysplasia group, and the low-grade trochlear dysplasia group and the normal group (P<0.05). Conclusions There are significant differences in patellar type distribution between LPD patients and healthy individuals. Type II and III of the patellae are common in LPD patients, while type I is very rare. The morphology of the femoral trochlea and patellar position have a certain correlation with the distribution of patellar types. The more severe the dysplasia of the femoral trochlea, the more likely it is to be accompanied by Wiberg type Ⅲ patella. Patella with a high position is more likely to be accompanied by Wiberg Ⅲ patella.
Key words
knee joint /
patellar dislocation /
patellar morphology /
anatomic parameter /
magnetic resonance imaging
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