Footballers’ feigning injury hampered an official FIFA study into concussion during last summer’s World Cup, a new report has found. Researchers who reviewed every head injury incident during games in Russia found new concussion protocols were “ineffective” in almost two thirds of matches at the tournament. New rules allowed referees to stop a game for three minutes while players with signs of concussion received treatment from a physiotherapist. They also allowed a second medic to view replays and assist with decision making. But the study pointed out that “gamesmanship” was a limitation to the work. The study, published in the journal Jama Neurology, said video observation was “insufficient” to diagnose a concussion as “some players may have been feigning injury”. Overall, the rate of teams failing to follow guidelines after head clashes was marginally higher than the previous World Cup in 2014, when concussion was a major controversy. In the 2014 final, Germany midfielder Christoph Kramer collapsed 14 minutes after being involved in a collision, saying afterwards: “I don’t know anything from the first half.” The furore prompted Fifa to change its head-injury protocols in time for this summer’s tournament, but ignored calls for rugby-style concussion time-outs. The report, by…