The number of concussions suffered by NFL players on kickoffs dropped sharply last season after the league changed its kickoff rule, contributing to a small decline in the overall number of such injuries, according to an analysis of injury data performed for the players’ union.

Players suffered 266 concussions last season, including 20 on kickoffs, according to the study released Tuesday by Edgeworth Economics, a consulting firm. That was down from 270 concussions suffered by NFL players during the 2010 season, 35 of them on kickoffs.

The NFL changed its kickoff rule before last season in an attempt to reduce injuries, particularly head injuries, moving the spot of the kickoff closer to the opposite goal line. That greatly reduced the number of kickoff returns and concussions on returns, but drew complaints from many players, coaches and fans because it increased the number of touchbacks.

“It is entirely due to the decrease in concussions on kickoffs,” said Jesse David, a statistician and economist who is a senior vice president at Edgeworth. “That [rule change] did what they intended it to do.”

The number of concussions suffered by players increased every season since 2004, the first year included in the study. The rise could be attributable in part, David said, to players reporting concussions more often and heightened awareness by NFL teams and the league of brain injuries.

“It’s possible some of that is increased recognition by the league,” David said in a telephone interview.

The NFL declined to comment. The study’s findings were consistent with previous assertions by the league that concussions suffered by players on kickoffs were down sharply last season because of the new rule.

George Atallah, the union’s assistant executive director of external affairs, said: “It’s always good to have independent verification of the information provided by the league.”

The new data was released at a time when thousands of former NFL players have sued the league over the effects of concussions.

The NFL has taken steps in recent seasons to reduce the number of concussions suffered by players and improve methods for identifying and treating brain injuries.

The analysis also covered the overall number of injuries suffered by players. According to the study, NFL players suffered a total of 4,493 injuries last season, up from 3,191 injuries in the 2010 season.

Much of that increase could be attributed to minor injuries that did not force a player from the game, David said. That portion of the increase, he said, could be due to the manner in which injuries were recorded under the league’s system. Such minor injuries may have been listed last season but not reported in previous seasons, he said.

Major injuries, defined as those that sidelined a player for at least three weeks, were up only slightly last season to 641, two more than in 2010. But moderate injuries, which forced a player out for one to three weeks, increased from 633 in 2010 to 739 last season.

“Serious injuries are still on the rise,” David said.

David said his firm has not yet processed the data to determine which types of injuries have increased the most.

“I think the overall big picture is that injuries continue to increase, including significant injuries,” David said. “With concussions, there is a general trend that continues to be up, although there was a slight decrease in 2011 for the first time in several years due to the reduction in concussions on kickoffs.”

The union cited the risk of increased injuries when it rejected a proposal by the league during last year’s labor negotiations to lengthen the regular season from 16 to 18 games while reducing the preseason from four games to two.

David said overall injuries tend to decline over the course of a season, but brain injuries tend to increase.

According to David, Edgeworth Economics performed its analysis without pay or direction from the NFL Players Association. The firm previously did work for the union during the NFL lockout last year, David said, then updated its study by asking the union to supply new injury data.