Quality assessment of radiological measurements of trochlear dysplasia; a literature review

Purpose: To make a systematic review with quality assessments of the known measurements used to describe trochlear dysplasia. Methods: A systematic literature search was conducted in the databases PubMed and Embase using the search string “trochlea dysplasia OR trochlear dysplasia”. Papers were screened for their relevance based on predefined parameters, and all measurements showing a statistical association between trochlear dysplasia and patellar instability were presented. Four experts evaluated the quality of the measures using a purpose-made quality scale. Results: The search generated 600 papers of which eight were chosen for review. Thirty-three unique measurements were identified and described in order of their date of publication. The lateral trochlea inclination was rated highest by the expert panel. The crossing sign, the trochlea bump, the TT–TG distance, the trochlea depth and the ventral trochlea prominence also had high ratings. Conclusion: Thirty-three unique measurements were identified with the lateral trochlea inclination as the highest rated measurement by the expert panel, and it is recommended for use in assessment of trochlear dysplasia. The crossing sign, the trochlea bump, the TT–TG, the trochlea depth and the ventral trochlea prominence were also rated well and can be recommended for use. Level of evidence: V