Predicting Injury in the NBA: A Case Study of Derrick Rose's ACL Tear

 by Imran Rahman

A respected franchise has an analytic department in their main office to try and make sense of the numbers the athletes churn out while on the court in the hopes of getting a statistical edge over other teams, to aid draft picks, trade opportunities and to maybe spot an undervalued champion in the prospects. But as injuries are increasing at an alarming rate coupled with the aggressive nature of the league; a solution is needed to find the injury-prone players and identify faults in their game that could cause these injuries.

At a time where he was considered as one of the best players in the NBA, a young and athletic Derrick Rose lit up the league with some of the most explosive characteristics ever seen by any player in the point guard position in the history of the NBA. A fan favourite,  Rose would lead the Bulls to 62 wins and finish on top of the eastern conference. He averaged 25.0 points, 7.7 assists, 4.1 rebounds and a steal per game in the 2010/11 season. But it all changed after one game. During the first-round playoff series against the 76’ers, Rose landed awkwardly and tore the anterior cruciate ligament (ACL) in his left knee. This started the downwards spiral from the youngest MVP in NBA History to a completely different player.

By using Derrick Rose as a case study, I hope to shed light on some of the points of interest fans and sports analysts should have used to identify flaws in his playstyle, both biomedically and through the mindset of Chicago bulls management which eventually led to this heart-shattering injury. 

The word injury prevention itself is oxymoronic, if NBA teams could prevent injury, they would rightfully do so. But over the years it has been a challenge to predict the frequency and nature of injuries as they have risen around 12.4 - 15 % over the past decade. NBA teams have realised that keeping the team’s franchise player on the court for long periods of time will have repercussions for the team as playtime will always be negatively proportionate to longevity and overall quality of play in the years to come.

Using statistics 

fatigue: defined as the depletion of mental and physical resources and was operationally defined by accumulated time in competitions with inadequate recovery time. Two variables were used to represent player fatigue: accumulated time in competition with inadequate recovery time. Two variables were used to represent player fatigue: accumulated minutes in competition, which was calculated as total minutes over 96 (constant of play termed by Melanie Lewis - University of Oklahoma). This was made experimentally by taking average injury reports over the years.

performance load: with franchise players, a lot is riding on their shoulders to put up all-star numbers to carry their team. Stats can be variable. For instance, a big man who plays centre could have rebounds per game as his stat while an athletic point guard like Derrick Rose could have more general FGA (field goal attempts) per game inside the D. These stats would be proportionate to injury, as getting these numbers would mean that the defenders are more likely going to be guarding the player closely and finishing at the rim would be harder as defenders would be on you. This was the case of D Rose.

demographic variables: variables such as height, weight, position and general BMI could have an increasingly important role in determining injury rate as certain variables can link together to make a player more injury-prone. A point guard (smaller player) who consistently finishes at the rim with contact is going to be more injury prone than the same point guard who is more 3 points centric. These specific statistics would have been able to distinguish D Rose as a high risk player as he had a tendency to finish at the rim coupled with an awkward landing stance landing on the ground.

Using mechanical knowledge of anterior cruciate ligament to predict injuries

Dynamic knee stability is affected by both passive and active joint restraints. The anterior cruciate ligament (ACL) has long been considered the primary passive restraint to the anterior movement of the tibia. The ACL contributes to knee rotational stability in both frontal and transverse planes due to its specific orientation.

Injuries to the ACL are one of the most common and devastating knee injuries. These often result in joint effusion, altered movement, muscle weakness, reduced functional performance and may lead to the loss of an entire season of sports participation among athletes. ACL injuries are also associated with long-term clinical sequelae that include meniscal tears, chondral lesions and an increased risk of early-onset post-traumatic osteoarthritis.

The ACL has long been thought to have poor healing capacity, with a substantially high rate of failure (40% to 100%) even after surgical repair using suture.

Most ACL injuries are a result of a non-contact injury (not a direct blow to the joint) but rather a sharp cutting motion which is more apparent in basketball. This has been theorised to be a neuromuscular control deficit, a problem in which neuromuscular control is lost which results in excessive joint loads due to muscle loss and eventually a tear. These injuries are multiplanar meaning they can occur due to various different landing positions.

D Rose had a tendency to land with his leg completely straight, which sent shockwaves up his leg and into his kneecap. As the momentum is not distributed evenly over the hips, this sharp cutting motion would have been enough to cause this tear. By looking over game footage and going over players' landing positions, a more general trend can be seen between these straight-footed landing positions and injury rate.

The main reason I am advocating for a change in statistical reasoning is that future careers are in jeopardy due to these life-changing injuries. Many young players such as young Ja Morant in Memphis shadow Rose's horrifying acrobatics and improper landings. Poor care and knowledge of form may lead to detrimental effects to younger players that carry the NBA through the generations and keep the sport being one of the most enjoyable events for fans all over the world. In my opinion, improving players' perception of situations and proper management of players by teams will lead to success.

"My thing is just staying positive. Find that thing you love doing and dedicate yourself to it. You're going to have to sacrifice a lot of things if you want to achieve the goals you want to achieve." - Derrick Rose.