[Steven Zahm]

@ Fabrice

When you say user, do you mean the categories assigned to an entry?

This would work:

// Grab an instance of the Connections object.
$instance = Connections_Directory();

$terms_r = $instance->term->getTermRelationships( $entry->getID() );

$terms = cnTerm::get( 'category', array( 'child_of' => 73 ) );

foreach ( $terms as $term ) {
    if ( ! in_array( $term->term_id, $terms_r ) ) continue;

    echo $term->name;
}