連想配列を任意のキーでソートする

$hoge = $_SESSION[ranking];
$i = 0;
foreach($hoge as $key => $row){
     $id[$key] = $row["id"];
     $counts[$key] = $row["counts"];
     $i ++;
}
array_multisort($counts,SORT_DESC,$hoge);

echo '<pre>';
var_dump($hoge);
echo '</pre>';