Reliability and clinical features associated with the IPSG MRI tibiotalar and subtalar joint scores in children, adolescents and young adults with haemophilia.

Objectives: To assess the reliability of the IPSG MRI scale for tibiotalar (TTJ) and subtalar joint (STJ) changes in young haemophilic patients, correlating MRI findings with functional scores and 3D-rearfoot kinematics.

Methods: A total of 37 haemophilic patients underwent bilateral MRI of the footankle, clinical evaluation and quantitative assessment of their 3D-rearfoot kinematics during walking. TTJ and STJ soft tissues were assessed twice along with osteochondral changes by two radiologists using the IPSG MRI scale. Inter- and intra-observer reproducibility of MRI scoring were tested by means of kappa statistics. Correlational analyses were performed between MRI findings and the Haemophilia Joint Health Score 2.1 (HJHS) and 3D-rearfoot kinematic data.

Results: The intra-reader reliability of MRI scoring was good to excellent (Kappa: 0.62-1), whereas the inter-reader reliability was moderate to good (Kappa: 0.54-0.79). Weak yet significant correlations were found between the frontal plane rearfoot range of motion (ROM) during loading response of gait and STJ score, as well as between frontal plane rearfoot ROM during the terminal stance phase and the rearfoot osteochondral lesions.

Conclusion: The IPSG score appears applicable to not only the TTJ but also the STJ. Contrary to TTJ lesions, those of the STJ do not correlate with the HJHS but do with 3D-rearfoot kinematic data.