While the Raiders have provided little detail about the injury that has sidelined new wide receiver Antonio Brown for most of camp, reports on the nature of Brown’s ailment have begun to emerge.
Brown issued the first hint himself, when he posted pictures on social media last week of what appeared to be a skin issue on the bottom of his feet. Tuesday, Pro Football Talk reported that Brown has frostbite on his feet after entering a cryotherapy chamber without proper footwear.
Wednesday, NFL Network also reported Brown used a cryogenic chamber without appropriate footwear. ESPN, meanwhile, reported that Brown has “extreme frostbite” on his feet, and that the Raiders have “no timetable” regarding Brown’s return.
The Raiders have not specified Brown’s injury. If he is dealing with frostbite, his recovery time would likely depend on the degree of injury, said Dr. Benjamin Ma, a professor of orthopaedic surgery at UCSF and chief of the UCSF Sports Medicine and Shoulder Service.
“Frostbite is like a burn to the skin,” Ma said. “A first-degree burn means just the epidermis is injured — it’s hot, it’s painful. Second-degree is you have these blisters. Third-degree burns is when you go down to the subdermal layer and actually lose some of the sensation.
“First- and second-degree burns are the most painful. Third- and fourth-degree, you basically don’t feel it, because the nerves are already hurt. But those are the really bad ones.”
As revealed in the pilot episode of HBO’s “Hard Knocks” on Tuesday night, Brown was dealing with his ailment several days before the start of training camp. He participated in the Raiders’ fourth practice of camp last week, running 1-on-1 routes against defensive backs, but left the field early that day and has not practiced since.
“Hard Knocks” also included a scene with Raiders’ trainer Rod Martin saying Brown “can’t handle the sharp cuts” running routes.
“For (his feet) to be peeling, it may be one of the lower levels,” Ma said. “If it’s still hurting, he won’t be able to kind of make the cuts and the moves he has.”
In a 2016 report, the FDA defined whole-body cryotherapy as “‘super-cooling’ of the body for therapeutic purposes.” In whole-body cryotherapy, a person is exposed — usually for 2-4 minutes — to “ultra-low temperatures.” It is often used to improve recovery after workouts, though the FDA in 2016 questioned its ability to treat certain diseases and conditions.
On Wednesday, Dr. David Chao, a former NFL team doctor, wrote a column for the San Diego Union-Tribune expressing doubt that Brown developed frostbite from cryotherapy treatment. Chao cited, among other factors, the time it takes to develop frostbite and the appearance of Brown’s feet in the photos Brown posted.
Chao wrote that Brown could have had a prior issue — Chao suggests skin maceration (the softening and breaking down of skin after advanced exposure to moisture) in training may have worsened with cryotherapy.
“Assuming Brown then used a cryotherapy machine without proper foot protection, in wet socks or with ‘wet’ macerated feet, the cold would conduct against the moisture,” Chao wrote. “It would then freeze the skin only on the moist soles of the outer layer of skin on his feet and not on his toes, tops of his feet or arch.”
Brown reportedly saw a foot specialist over the weekend and head coach Jon Gruden said on Tuesday that Brown was still “gathering information” on his ailment. Gruden said he had “no new news” on Brown’s status or when the receiver might return to the field.
Ma, the UCSF professor, said that in cases of requiring new skin to grow back, recovery time usually “depends on the impact — how big the (affected) area is and where the area is also.”
“The nice thing about the bottom of the feet is you have the thickest skin on the bottom of the feet because that’s where you’re standing and walking all the time,” Ma said. “Even if the first few layers come off there, you can come back quickly.”
Nearly two weeks into camp, the extent of Brown’s injury remains unclear. After Wednesday’s practice, quarterback Derek Carr was asked how players are treating the questions surrounding Brown’s absence.
“To be completely honest, we haven’t even paid attention to what’s going on,” Carr said. “And that’s usual when anybody’s hurt or dealing with something. You’re like, we miss him, but there is so much we’re worrying about. We don’t get into anybody else’s business. But we miss him. And we can’t wait for him to get back.”
Matt Kawahara is a San Francisco Chronicle staff writer. Email: firstname.lastname@example.org Twitter: @matthewkawahara
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