Radial fibre proportions in human knee joint menisci - Measurement by scanning optical microscopy

The proportions of medial and lateral knee joint menisci represented by rad ially orientated collagen (COL) were measured in 42 specimens from 24 hospi tal patients examined post-mor-tem. Images of the fibre bundles were obtain ed by the 488-nm laser confocal scanning of hydrated, fixed radial blocks t aken from the anterior, middle and posterior regions of the menisci after s taining with picro-Sirius red. Measurements of the percentage of each image occupied by fluorescent, doubly refractile COL were made by means of a Kon tron IBAS image analyser, after interactive segmentation. In areas adjoinin g the outer, lateral parts of both the medial and lateral menisci, the prop ortion of all samples identified as radial COL was 7.56 +/- 0.28%. The corr esponding figure for areas near the inner, medial edges of the menisci was 17.80 +/- 0.80%. However, no relationship was demonstrable between age and sex and meniscal radial fibre optical density, and there was no difference between the proportion of radial fibres in the anterior, middle or posterio r regions.