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

Abstract

Purpose The purpose of this systematic review was to critically assess the quality of papers that report on the intra-and inter-observer repeatability of the Dejour classification for trochlear dysplasia, and to identify the possible causes for poor repeatability. Methods Two authors independently conducted an electronic search (four databases) on 8 February 2023 for studies (English or French) that assessed trochlear dysplasia classifications on imaging of skeletally mature participants. Exclusion criteria were reviews of clinical studies, conference proceedings, or editorials. After title, abstract, and full-text screening, characteristics of eligible studies were tabulated (author, year, journal, study design, cohort characteristics, and intra-and/or interobserver agreement coefficients). The methodological quality of studies was assessed using the Joanna Briggs Institute (JBI) checklist for analytical cross-sectional studies. Authors analysed three components of the included studies: (1) classifications based on true lateral radiographs and slice imaging; (2) dysplasia graded into Type A vs B vs C vs D and 3) coefficients of intra-and/or inter-observer agreement. ResultsThe electronic search returned 3,178 references, and after removal of duplicates and irrelevant studies, ten were eligible for data extraction. A second search (31 July 2023) yielded one additional study. Eight studies did not include lateral radiographs, two studies did not explicitly state if radiographs were true lateral views, and one used true lateral radiographs in isolation. Classification of trochlear dysplasia into A vs B vs C vs D using different imaging modalities resulted in moderate to near-perfect intra-observer agreement, and slight to near-perfect inter-observer agreement. Studies distinguished between moderate and severe dysplasia using a variety of combinations: A vs B/C/D, A/B vs C/D and A/C vs B/D. Conclusion This systematic review revealed that the Dejour classification remains the most widely used to assess trochlear dysplasia and that the majority of studies that assessed the reliability of the Dejour classification, reported moderate to nearperfect inter-observer agreement; however, pooling of results for comparison among the included studies was inappropriate due to substantial variation in imaging protocols and non-standardised criteria to distinguish severe from moderate dysplasia. Level of evidence Level IV. Trial registryThe PROSPERO registration number is CRD42023386731.

Shallow trochlear groove and narrow medial trochlear width at the proximal trochlea in patients with trochlear dysplasia: A three‐dimensional computed tomography analysis

“…Additionally, the cut‐off value of LP‐MEC could be determined to differentiate type A from types B, C and D. The elevated TG‐TEA and MP‐MEC in the proximal planes observed in types B and D indicated the prominence of morphological features previously identified in the dysplasia group: shallower trochlear depth and narrower medial trochlear width. This provides quantitative evidence to support the consideration of sulcus‐deepening trochleoplasty in patients of severe dysplasia, specifically types B and D, when supratrochlear measures >5 mm [13, 28]. Overall, our approach of quantifying multiple parameters across various patellar tracking angles in 3D analysis may be useful for differentiating between the four types of Dejour classification.…”

“…Given the significant differences in TG-TEA and MP-MEC between the control and dysplasia groups, further comparative analyses were conducted after Abbreviations: LP-MEC, distance from the medial epicondyle (MEC) to the point on the transepicondylar axis (TEA) corresponding to the most cortical point of the lateral condyle; LP-TEA, distance from the TEA to the most cortical point of the lateral condyle, where LP is the lateral peak; MP-MEC, distance from the MEC to the point on the TEA corresponding to the most cortical point of the medial condyle; MP-TEA, distance from the TEA to the most cortical point of the medial condyle, where MP is the medial peak; TG-MEC, distance from the MEC to the point on the TEA corresponding to the deepest point of the trochlea; TG-TEA, distance from the TEA to the deepest point of the trochlea, where TG is the trochlear groove. [13,28]. Overall, our approach of quantifying multiple parameters across various patellar tracking angles in 3D analysis may be useful for differentiating between the four types of Dejour classification.…”

“…Because our study was based on CT data, which may not be the optimal imaging modality for cartilage evaluation, the articular margin of the proximal trochlea could not be precisely defined [26, 40]. It is regrettable to report that the supratrochlear spur, a key criterion of the Dejour classification, could not be quantified in our 3D analysis [28]. Lastly, utilising the TEA as a consistent reference for the patellar tracking angle may not be applicable in patients with rotational malalignment of the distal femur [20].…”

The Dejour classification for trochlear dysplasia shows slight interobserver and substantial intraobserver reliability

“…MRI reveals certain features of the trochlear groove but misses the correlation with the lateral radiograph, which can give a full picture of the trochlea because of the superimposition of prominences [13]. Finally, a recent systematic review found that there is substantial variation, in the evidence base, regarding imaging protocols and nonstandardised criteria to distinguish dysplasia [22].…”

Towards a Comprehensive Classification for Trochlear Dysplasia: Bridging the Imaging Gap

“…The misinterpretation or undervaluation of this condition can result in inappropriate or unsuccessful treatment. However, the analysis and classification of this condition are complex, posing a significant challenge for clinicians [2].Currently, only a few widely accepted classifications exist in the literature. Henri Dejour, in 1987, based his classification on the level of the crossing sign on lateral knee radiographs [3].…”