Assessment Of Patellar Morphology In Trochlear Dysplasia On Computed Tomography Scans

Objective: The objective of the current study was to evaluate patellar morphology of trochlear dysplasia and normal knees in different genders and different severity of trochlear dysplasia on computed tomography(CT)scans.Methods: From December 2013 to December 2018,75 patients with trochlear dysplasia(110 knees)were collected into the experimental group,and an age and body mass index(BMI)matched cohort of 46 patients with normal trochlear shape(57 knees)were randomly selected into the control group.According to gender,the experimental group was divided into the female experimental group(Group FE,47 patients,72 knees)and male experimental group(Group ME,28 patients,38 knees);the control group was divided into the female control group(Group FC,24 patients,31 knees)and male control group(Group MC,22 patients,26 knees).Furthermore,according to the severity of trochlear dysplasia,the Group FE was divided into the female low-grade dysplasia group(Group FL,20 knees)and female high-grade dysplasia group(Group FH,52 knees);the Group ME was divided into the male low-grade dysplasia group(Group ML,16 knees)and male high-grade dysplasia group(Group MH,22 knees).All participants had undergone CT scans in the supine position,the patellar width,thickness,the lateral patellar facet angle,and the Wiberg angle,Wiberg index were measured and compared.Results: In trochlear dysplasia knees,the patellar width,thickness,and the lateral patellar facet angle were significantly smaller,the Wiberg index was significantly larger than those in normal knees,regardless of the genders(P<0.05);and there was no statistically significant difference in the Wiberg angle(P>0.05).In the female groups,the patellar width,thickness,and the Wiberg angle were significantly smaller,the lateral patellar facet angle was significantly larger than those in the male groups(P<0.05);and there was no significant difference in the Wiberg index(P>0.05).In the low-grade dysplasia group,the Wiberg index was smaller than that in the high-grade dysplasia group(P<0.05),regardless of the genders;but there was no significant difference in the patellar width,thickness,the lateral patellar facet angle,and the Wiberg angle in low-and high-grade dysplasia(P>0.05).Conclusions: On CT scans,the patella in trochlear dysplasia had a smaller width,a thinner thickness,a lengthened lateral facet,and a more flattened articular facet.In addition,the patellar articular facet was more prominent in female patients.With the severity of trochlear dysplasia increased,the lateral patellar facet became longer.And the abnormal stress distribution on the patella necessarily influenced patellar morphology in trochlear dysaplasia.