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In Street Clothes

Covering sports injuries from the perspective of a certified athletic trainer and backed by analytics.

A 5-year Look at ACL Injuries in the NBA

Earlier today my friend and colleague Will Carroll (@injuryexpert) tweeted an interesting statistic. Carroll revealed that Geno Atkins’ torn anterior cruciate ligament (ACL) was the 40th reported ACL injury in the NFL this season. The question was raised for an interleague comparison between the NFL and the NBA. While I don’t have the numbers for the NFL I was able to breakdown ACL injuries in the NBA to a much larger degree and discovered several interesting facts.

Examining the last five seasons I uncovered 25 reports of ACL injuries amongst NBA players. I omitted players that were drafted despite torn ACLs that occurred in college including Nerlens Noel and De’Sean Butler. DeJuan Blair was also omitted despite playing without ACLs in either knee. ACL injuries occurred at various points of the season including the offseason (2), preseason (2), regular season (19), and playoffs (5). Two players, Michael Redd and Josh Howard, suffered multiple ACL injuries in the measured period. Redd tore and retore his left ACL in consecutive seasons while Howard tore his left ACL with Washington in the 2009-10 season and then his right while with Minnesota during the 2012-13 campaign.

The average number of games missed for each player was 47, though the number could easily be much higher. Several players including Howard and Jeff Ayres were waived following their injuries, preventing them from accruing more missed games. Games missed in the 2013-14 season were not included in the totals or averages. 12 of the players to endure ACL injuries would miss games in two different seasons. Two players, Baron Davis and Kareem Rush, have not played in another NBA game since sustaining their injury.

Further examination indicates the majority of these injuries occurred in noncontact fashion. 20 of the 25 observed injuries did not involve contact from an opposing player or teammate with most coming following a sudden deceleration motion. This observation is likely the primary reason for the discrepancy in NFL and NBA ACL injuries. While noncontact ACL injuries due occur in the NFL, like Reggie Wayne’s recent knee injury, the torsion and impact that the lower leg is subjected to during contact in football rarely occurs on a basketball court. The NFL also has a significantly larger sample size to work with as each team consists of 53 players, over 3.5 times more than a 15-man roster of a NBA team.

The 23 effected players come from 16 different teams. The Celtics and Timberwolves led the way with four ACL injuries apiece. The Bucks, Knicks, and Wizards each have two documented cases, though both of Milwaukee’s incidences involved the same player.

A final look at each ACL injury shows that an isolated ACL injury occurred in 13 of the 25 examined cases. Of the remaining 12, MCL involvement was the most frequent accompanying injury occurring eight times. Meniscus damage came in second, occurring in four of the 12 non-isolated ACL injuries.