Get article or content menu item from backend
<?php
// Get site menu - specially pass `site` argument as you are going to get site menu from backend.
$menu = JFactory::getApplication()->getMenu('site');
// Get menu item based on query
$menuItems = $menu->getItems('link', 'index.php?option=com_content&view=article&id=' . (int) $this->item->id);