The knuckle and the sirloin tip are the same piece of the round, and the one USDA prices is the peeled one, IMPS 167A. It is the group of muscles on the front of the hind leg, above the knee: the rectus femoris and the three vastus muscles. Peeled means the cap muscle on its outside, the tensor fasciae latae, has come off with the fat and the silver skin.
Peeled vs unpeeled
The unpeeled knuckle, IMPS 167, keeps that cap muscle and its fat cover. The peeled knuckle, 167A, is the same piece with the cap, the fat and the skin tissue removed, and USDA prints it at fat option 4, practically free of fat. The cap is the difference in weight too: IMPS sizes the unpeeled knuckle at 8-9, 9-11, 11-13 and 13-up lb, and the peeled one a pound lighter in each range.
USDA's daily report has carried only the peeled line since April 2007; the unpeeled "round, knuckle" line stopped printing then. So an unpeeled quote has no USDA price to check against: price it off the peeled line less the trim.
The 167 family
| IMPS | Cut | Weights (lb) |
|---|---|---|
| 167 | Knuckle, cap on | 8-9, 9-11, 11-13, 13-up |
| 167A | Knuckle, peeled | 7-8, 8-10, 10-12, 12-up |
| 167B | Full sirloin tip, cap on, part of the bottom sirloin attached | 10-12, 12-14, 14-16, 16-up |
| 167C | Full sirloin tip, trimmed | 9-11, 11-13, 13-15, 15-up |
| 167D | Peeled knuckle, 2-piece | 5-7, 7-9, 9-12, 12-up |
| 167E | Center roast (the rectus femoris alone) | 2-3, 3-5, 5-up |
| 167F | Side roast (the vastus lateralis alone) | 2-3, 3-4, 4-up |
The 2-piece is a peeled knuckle split along its seam into the center and side muscles, with the small inner muscles taken out. The center roast and side roast are those two pieces sold on their own. USDA prints none of them.
Grade barely matters
Over the five years to August 2026, Choice peeled knuckle printed a median 0.5 percent over Select, and above it on only 59 percent of days. A lean roasting and grinding muscle does not pay for marbling. Buy the grade that is cheaper that day.
How it prices: off the grind
The knuckle is 18 percent of the round pounds USDA reports, third behind the top inside round at 31 and the outside round at 22, and it is the piece that moves between whole-muscle and grind most freely: sirloin tip steaks, kabob and stir-fry cuts on one side, lean grind raw material on the other.
That shows in the price. Over the last five years the Choice peeled knuckle printed above fresh 90CL on 94 percent of days, by a median 36 cents a pound, and it has never spent a year below it. It sits under the top inside round denuded on 82 percent of days, by a median 22 cents, above the outside round on 91 percent, and about level with the eye of round. When 90CL runs, the knuckle follows, because the grinder is its next buyer.
When it is strong
Measured against the Choice cutout, so a move in the whole market cannot pass for a season, the knuckle ran above its own yearly average in January and October in 9 of the 10 years from 2016 to 2025, and in February in 8. It ran above in April, May and June in only 1 of the 10. Lean roasts and lean grinds sell in the cold months; the spring belongs to the middles.