Measurement of coronal plane patellar mobility in normal subjects.

This study evaluated an instrument for measuring patellar mobility in the coronal plane in normal subjects, established baseline quantitative data and compared with methods of measurement described in the literature. This data can be used as a baseline for clinical assessment of patellar mobility. The findings suggest that 8-20 mm displacement is normal patellar mobility in the coronal plane. Displacement less than 8 mm may be considered as retinacular tightness and displacement greater than 20 mm considered as abnormal retinacular laxity.