Patella subluxation assessed on dynamic MRI has previously been shown to be associated with anterior knee pain. In this MRI study of 60 patients we investigated the relationship between subluxation and multiple bony, cartilaginous and soft-tissue factors that might predispose to subluxation using discriminant function analysis.

Patella engagement (% of patella cartilage overlapping with trochlea cartilage) had the strongest relationship with subluxation. Patellae with > 30% engagement tended not to sublux; those with < 30% tended to sublux. Other factors that were associated with subluxation included the tibial tubercle-trochlea notch distance, vastus medialis obliquus distance from patella, patella alta, and the bony and cartilaginous sulcus angles in the superior part of the trochlea. No relationship was found between subluxation and sulcus angles for cartilage and bone in the middle and lower part of the trochlea, cartilage thicknesses and Wiberg classification of the patella.

This study indicates that patella engagement is a key factor associated with patellar subluxation. This suggests that in patients with anterior knee pain with subluxation, resistant to conservative management, surgery directed towards improving patella engagement should be considered. A clinical trial is necessary to test this hypothesis.

We developed the Oxford ankle foot questionnaire to assess the disability associated with foot and ankle problems in children aged from five to 16 years. A survey of 158 children and their parents was carried out to determine the content, scaling, reliability and validity of the instrument. Scores from the questionnaire can be calculated to measure the effect of foot or ankle problems on three domains of children’s lives: physical, school and play, and emotional. Scores for each domain were shown to be internally consistent, stable, and to vary little whether reported by child or parent. Satisfactory face, content and construct validity were demonstrated. The questionnaire is appropriate for children with a range of conditions and can provide clinically useful information to supplement other assessment methods. We are currently carrying out further work to assess the responsiveness of questionnaire scores to change over time and with treatment.