<?php
$groupRadio1 = null; // valore (1, 2, 3) che può essere letto dal DB,
if(!empty($_POST) and empty($_POST["groupRadio1"])) { $_POST["groupRadio1"] = $_POST["groupRadio1h"]; }
print_r($_POST); echo "<br /><br />";
?>
<!DOCTYPE html>
<html>
<body>
<form method="post" action="<?php echo $_SERVER['PHP_SELF']; ?>">
<table border="0">
<tr>
<td><input type="radio" name="groupRadio1" value="1" <?= ($groupRadio1 == 1) ? "checked " : ""; ?>/></td>
<td>SI</td>
</tr>
<tr>
<td><input type="radio" name="groupRadio1" value="2" <?= ($groupRadio1 == 2) ? "checked " : ""; ?>/></td>
<td>NO</td>
</tr>
<tr>
<td><input type="radio" name="groupRadio1" value="3" <?= ($groupRadio1 == 3) ? "checked " : ""; ?>/></td>
<td>N/A</td>
</tr>
</table>
<br />
<input type="hidden" value="3" name="groupRadio1h">
<br />
<br />
<input type="submit" value="Submit Form">
</form>
</body>
</html>