Most NFL linemen wear rigid, hinged knee braces designed to prevent ligament injuries from the constant lateral collisions at the line of scrimmage. The most common brands on NFL sidelines are DonJoy, Össur (CTi), and Breg, with specific models chosen based on whether a player is bracing preventively or protecting a previous injury. There’s no league-wide mandate requiring them, but many teams and individual players treat them as essential gear.
The Most Common Brands and Models
DonJoy dominates the NFL lineman market. The DonJoy Defiance is built specifically for the repeated impact that linemen absorb on every play, with a rigid frame and heavy-duty hinge system. For off-the-shelf prevention, the DonJoy Armor with Standard Hinge is a popular choice that protects the ligaments on both sides of the knee. Players who want additional ACL protection often use the DonJoy Performance Bionic FullStop, which adds a mechanism to limit hyperextension.
Össur’s CTi line is the other major player at the professional level. The CTi Custom, CTi3, and C180 Rocket all use carbon fiber frames paired with the company’s Accutrac hinge design. The carbon fiber keeps the brace light relative to its strength, which matters when a 320-pound lineman needs to move laterally on every snap. Many of these braces are custom-molded to the player’s leg for a precise fit, which reduces slipping during play.
Breg is also seen on NFL rosters, though DonJoy and Össur tend to get the most visibility. The choice often comes down to team equipment contracts, player preference, and what the athletic training staff recommends based on a player’s injury history.
How These Braces Work
NFL-grade knee braces use two rigid frames strapped around the thigh and shin, connected by a polycentric hinge at the knee joint. This construction absorbs stress hitting the knee from the side while still allowing full bending and straightening during play. When a lineman takes a hit to the outside of the knee (a common scenario in trench warfare), the brace is meant to reduce how much the shinbone shifts sideways relative to the thighbone. That lateral force is what tears the MCL, one of the most common knee injuries in football.
The science on how well they actually work is more nuanced than you might expect. Lab studies using human specimens have shown little to no direct protective effect on the MCL from lateral impacts. However, research does show that these braces reduce bone acceleration during collisions, meaning the structures inside the knee experience less sudden force. The real-world benefit likely comes from this dampening effect combined with limiting the knee’s range of motion at extreme angles, even if the brace can’t fully absorb a direct blow from a 280-pound defensive tackle.
Custom vs. Off-the-Shelf
At the NFL level, most starters wear custom-molded braces. These are built from measurements or molds of the player’s leg, ensuring the brace stays in place during explosive movements. Carbon fiber is the standard frame material for custom professional braces because it offers high strength at low weight. A custom brace from Össur or DonJoy can cost $1,000 to $2,000 or more, but NFL teams cover this as part of their equipment budget.
Off-the-shelf models like the DonJoy Armor are more common among backup players, practice squad members, or players who prefer a less bulky option. These come in standard sizes and use aluminum or composite frames rather than full carbon fiber. They still provide meaningful lateral support but are more prone to shifting during play because they aren’t contoured to the individual leg.
Who’s Required to Wear Them
The NFL has no league-wide rule requiring knee braces for any position. The collective bargaining agreement between players and ownership actually prevents a blanket bracing mandate. Instead, the decision falls to individual teams and players. Some head coaches have imposed team-wide requirements for their offensive lines. In 2010, Buffalo Bills coach Chan Gailey made knee braces mandatory for all of his offensive linemen, a move that got attention around the league.
Beyond team mandates, many players choose to wear braces on their own. Research into NFL usage trends shows that bracing decisions are mainly player-specific, meaning personal comfort and injury history drive the choice more than any top-down policy. Offensive linemen are far more likely to wear them than defensive linemen, largely because offensive linemen set up in a more stationary stance and absorb lateral hits more predictably. Defensive linemen, who need to pursue ball carriers in open space, sometimes feel the brace restricts their lateral agility too much.
Why Linemen Specifically
Knee braces are far more common among linemen than any other position group in football, and the reason is mechanical. On every snap, offensive linemen plant their feet and absorb contact from defenders who are often hitting them from the side or at an angle. This creates a valgus force on the knee, where the joint is pushed inward while the foot stays planted. That’s the exact loading pattern that damages the MCL and, in worse cases, the ACL.
Skill position players like receivers and running backs rarely wear rigid knee braces because the weight and bulk, even a few ounces, can affect their speed and cutting ability. For a lineman who moves within a five-yard box on most plays, that tradeoff is worth it. The brace adds protection during the repetitive, high-force collisions that define their position without meaningfully limiting the movements they need to make.
What to Look for if You Play
If you’re a high school or college lineman looking at the same braces the pros wear, the key features to prioritize are a rigid frame (not a soft neoprene sleeve), bilateral hinges on both sides of the knee, and a snug fit that doesn’t slide down your leg during a drive block. The DonJoy Armor and DonJoy Defiance are available to consumers and represent the same design philosophy used at the NFL level, though at different price points.
Fit matters more than brand. A brace that migrates down your shin during play offers almost no protection because the hinge no longer aligns with your knee joint. If you can afford a custom-molded option, it will stay in place better and feel less restrictive. If you’re going off the shelf, measure carefully and use all the straps as intended. Many players tape the top strap to their thigh pad or skin to prevent slippage, a trick borrowed directly from NFL equipment staffs.