Two-type classification system for femoral trochlear dysplasia in recurrent patellar instability based on three-dimensional morphology

Abstract

Purpose Radiographic and two-dimensional (2D) CT/MRI analysis of femoral trochlear dysplasia play a signiicant role in surgical decision-making for recurrent patellar instability. However, the three-dimensional morphology of dysplastic trochlea is rarely studied due to the limitations of conventional imaging modalities. This study aimed to (1) develop a 3D morphological classiication for trochlear dysplasia based on the concavity of the trochlear groove and ( 2) analyze the interrater reliability of the classiication system. Methods The 3D trochleae of 132 knees with trochlear dysplasia and recurrent patellar instability were reconstructed using CT scan data and classiied using the innovative classiication criteria between January 2016 and June 2020. A concave trochlear sulcus with sloped medial and lateral trochlear facets was classiied as Type I trochlea. The trochlear groove with no concavity is classiied as Type II. Furthermore, in Type II, the trochlea with the elevated trochlear loor at the proximal part was identiied as IIa and the trochlea with the hypoplastic trochlear facets as IIb. The intra-and inter-rater reliability was examined using kappa (κ) statistics. Results The 3D classification system showed substantial intra-rater agreement and moderate interrater agreement (0.581 ~ 0.772). The intra-and interrater agreement of Dejour's four-grade classiication was fair-to-moderate (0.332 ~ 0.633). Eighty-one trochleae with concave trochlear sulcus were classiied as Type I, and ifty-one without concavity as Type II. Twenty-ive non-concave trochleae were classiied as type IIa due to the elevated trochlear loor and 26 trochleae into IIb with the hypoplasia of trochlear facets. Conclusion This study developed a 3D classiication system to classify trochlear dysplasia according to trochlear concavity and morphology of the trochlear facets. On CT/MRI scans or 3D reconstructions, the interpretation of features of dysplastic trochleae may vary, especially for the lat and convex trochleae. The novel system provides morphological evidence for when to consider trochleoplasty according to the diferent types of trochlear sulcus.

Inconsistent repeatability of the Dejour classification of trochlear dysplasia due to the variability of imaging modalities: a systematic review

“…No additional studies were identified from reference lists, which left ten relevant studies for data extraction [4,6,22,30,31,39,41,54,58,65]. The second electronic search on 31 July 2023 yielded one additional study published after the first electronic search, which was added to the analysis [50] (Fig.…”

“…Yang et al [65] reported that intra-observer agreement was moderate to substantial when classifying dysplasia into four categories, but substantial to near perfect when classifying dysplasia into two categories using CT. Fuchs et al [31] reported that intra-observer agreement was moderate to substantial when classifying dysplasia into four categories, but fair to near perfect when classifying dysplasia into two categories using MRI.…”

Gender Differences in Ethmoid Sinus Morphology

“…Moreover, prior studies analyzing the data in human skeleton system [15][16][17][18][19] have con rmed that the measured data from 3D reconstruction measurement results are more consistent and accurate than that from 2D measures. Some morphological studies have reported racial and gender differences in sinus [8, [14][15][16]. One recent study showed that Chinese ES was about 16% wider than examples from another study [13].…”

Association of Trochlear Length on Sagittal MRI to Trochlear Dysplasia in Knees With Patellar Instability

“…3 The abnormal shape of a dysplastic trochlea has been described on axial imaging as a decreased slope of the medial or lateral condyle as well as a decreased depth of the trochlear floor and abnormalities in trochlear width. 2,8,14,15,26 Several studies 5,6,17,23 have assessed patients who sustained first-time patellar dislocations and identified trochlear dysplasia as a primary risk factor for recurrent instability. While the cause of patellar instability is multifactorial, Christensen et al 10 noted in a retrospective study of 584 patients that the presence of trochlear dysplasia was the primary risk factor (odds ratio, 18.1) for the recurrence of instability after a first-time patellar dislocation episode.…”

“… 3 The abnormal shape of a dysplastic trochlea has been described on axial imaging as a decreased slope of the medial or lateral condyle as well as a decreased depth of the trochlear floor and abnormalities in trochlear width. 2 , 8 , 14 , 15 , 26 …”