The thick flank (US: beef knuckle) is a beef cut from the top of the round just beyond the sirloin and is the solid muscle group just above the kneecap. It provides a boneless cut that includes segments of the tri-tip muscle and of the caudal portion of the knuckle muscle. In some cases is may also include a segment of the sartorius muscle. It is a common name for the combination of the vastus lateralis, vastus intermedius, vastus medialist and rectus femoris muscles. A cow uses this group of muscles to move a hind leg. These muscles are located on the anterior side of a round bone, immediately above a knee cap.
The thick flank can weigh from 5.5 to 7.25 kg (12-16 lb) and is a useful cut for the home. It can be cut into steaks, cubed for kebabs, or trimmed, split and the two halves rolled and tied to make a small roasting joint suitable for spit-roasting. It is a tasty cut, though not as tender as sirloin.
