Tracy Walker wears a new pair of cleats in every football game he plays, or did at least until the Detroit Lions’ Week 3 game against the Minnesota Vikings earlier this year.

When Walker went out for pregame warmups, he felt his cleats sticking too much to the U.S. Bank Stadium turf, so he changed into a spare pair in the locker room before kickoff.

Walker assisted on a tackle on the Vikings’ first offensive snap, then tore his Achilles tendon a series later when he planted his left foot and drove to make a tackle.

He does not specifically recall his cleat catching on the turf that play, but as Walker has pondered his injury the past two months — and read up on concerns the NFL Players Association has about turf fields around the league — he’s convinced the slit-film turf surface in Minnesota contributed to his injury.

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“When I tore my Achilles, that was the first thing I thought about, like, ‘I switched cleats,’” Walker said. “So it’s just like, that’s — it could have been that. It could have been, I don’t know. That’s just my belief. I feel like that had a lot to do with it cause that day I remember, particularly, I don’t switch my cleats out and I remember Minnesota cause my new cleats were sticking, so I switched cleats.”

NFLPA president JC Tretter, in a Nov. 12 post on the NFLPA website, called for the league to immediately replace the playing surface at the six stadiums that use slit-film turf and ban it from future use in NFL stadiums.

Ford Field, MetLife Stadium in East Rutherford, New Jersey, the Superdome in New Orleans, Lucas Oil Stadium in Indianapolis and Paycor Stadium in Cincinnati also use the surface.

Ford Field last replaced its turf in 2019 and is scheduled to get a new synthetic field in 2024 or 2025. MetLife Stadium announced last week it is reviewing proposals for a new turf field.

Tretter, in his post, wrote that slit-film turf has higher rates of non-contact injuries, foot and ankle injuries, and injuries that cause players to miss time than monofilament or dual-fiber turf fields.

The NFL said in a statement, via Pro Football Talk, that concerns about slit-film turf are exaggerated.

“While slit-film surfaces, one type of synthetic material, have 2-3 more injuries per year, most of them are ankle sprains — a low-burden injury — whereas slit film also sees a lower rate of fewer high-burden ACL injuries compared to other synthetic fields,” NFL executive vice president of communications, public affairs and policy Jeff Miller said in the statement. “As a result, the league and NFLPA’s joint experts did not recommend any changes to surfaces at (our joint meeting on field surface safety) but agreed more study is needed.”

In addition to criticizing slit-film turf, Tretter renewed calls for NFL teams to “proactively change all field surfaces to natural grass” in a separate post, something several Lions players said they would like to see happen, too, though most acknowledge it’s far-fetched.

“I think grass is the way to go, by far,” Lions center Frank Ragnow said. “I don’t know about all the injuries and stuff like that, cause I don’t know the science behind it. But just like in general how your joints feel and everything feels, you feel 10 times better if you play or practice on the grass compared to turf.”

Tretter wrote there is a considerably higher rate of non-contact injuries on turf versus grass. ESPN reported that a third-party company the NFL and NFLPA use to analyze injury data showed a “notably” higher rates as recently as 2019, but said the numbers were nearly identical in 2021.

Anecdotally, several Lions said they suffered injuries they believe were due to playing on turf, or were exacerbated by the surface.

Receiver Josh Reynolds said he developed bursitis in his knee when he was driven hard into the MetLife turf in a game while playing for the Tennessee Titans last season, and fullback Jason Cabinda, the Lions’ NFLPA rep, said he tore his PCL in a game against the Atlanta Falcons last fall on a similar play at Mercedes-Benz Stadium.

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“It’s like playing on this (carpet in locker room),” Ragnow said. “There’s like literally just a little bit of carpet on concrete and it’s just hard on the knees, especially when you are 300-plus pounds. It’s a lot of — whether you’re just standing there. Like you ask the coaches after standing for a game on turf all day, they’re feeling it in their lower backs, too.”

Lions coach Dan Campbell said he has not noticed any problems with the Ford Field turf, though he can relate to his players’ preference to play on grass from his own playing days in the NFL.

‘Towards the end of my career was when the new stuff came in,” he said. “And look, the turf is always different, and certainly it feels better on your joints. Now, anytime you’re on any type of turf, it puts a little bit more of a strain on the joints, but as far as a difference, I never really saw or felt a difference. But there again, you’ve got to remember, that was all relative to what I knew, and there again, we played on carpet on turf, and so the new turf was like, ‘Wow, this is unbelievable.’”

Reynolds said playing on turf is preferable to some of the poorly-maintained grass fields in the NFL. Soldier Field in Chicago is notorious for having a bad grass surface, as is State Farm Stadium in Glendale, Arizona — an indoor stadium that has a retractable grass field that can be moved outside.

Cabinda said he does not see a day when the NFL goes all-grass but wants the league to raise its standards for fields across the board.

“For me to sit here and say, ‘Hey, we need to put natural grass inside of an indoor stadium,' and have it looked after and all this stuff in a feasible manner, it’s probably not going to be the case,” he said. “But to make sure we have the absolute best turf possible, not that slit-film turf and get rid of that and have better than that, we (can do that).”

Contact Dave Birkett at dbirkett@freepress.com. Follow him on Twitter @davebirkett.

This article originally appeared on Detroit Free Press: NFL playing surface debate reignites: 'Grass is the way to go, by far'