Agreement of radiographic measurements and patient-reported outcome in 61 patients with Legg-Calvé-Perthes disease at mean follow-up of 28 years.

It is unclear how patient-reported outcome in patients with Legg-Calvé-Perthes disease (LCPD) is correlated with radiographic outcome. It was therefore the aim of our long-term follow-up to evaluate the agreement of patient-reported outcome measures (PROM) with radiographic outcome in patients with a history of unilateral LCPD and a femoral head involvement of more than 50%. We further investigated to what extent the functional outcome (range of motion and Trendelenburg sign) correlates with PROM and radiographic outcome. At a mean follow-up of 28 years (15-42), 61 patients were investigated clinically and by plain radiography to evaluate the sphericity deviation score, femoral head enlargement and femoral neck growth inhibition. The patients also completed questionnaires for generic measures of health-related quality-of-life (ED-5D, EQ-visual analogue scale), the joint-specific Harris hip score and the nonarthritic hip score questionnaire. The radiographic measures sphericity deviation score, femoral head enlargement and femoral neck growth inhibition were strongly correlated with the joint-specific PROMs (Harris hip score and nonarthritic hip score) but not with EQ-5D and EQ-visual analogue scale. Inferior range of flexion and abduction and a positive Trendelenburg sign were associated with an inferior patient-reported outcome. Our findings highlight the importance of supporting femoral head re-modelling and containment and balancing trochanteric and femoral neck growth in patients with LCPD. To capture the whole picture of the outcome after LCPD, future studies should include a combination of radiographic measurements and joint-specific and generic outcome scores. Level of Evidence: Level III.