All the sports buzz in Philly this week is revolving around the Sam Bradford trade. Is he a good QB? Don't ask me, but ACLs are something I know about.

His first ACL injury was to his left knee in October 2013. From the video, it looked like it was a contact injury where he was pulled down from behind. It appeared that his foot got caught with a flexion rotation mechanism of injury. He injured the same knee this past August, which also looked like a contact injury from a direct blow to the knee causing hyperextension.

As we know, there are two types of ACL injury mechanisms, contact and non-contact. Contact injuries like Bradford's are usually more bad luck than pre-disposition. If he tore them running in the open field I would be more concerned about predisposition.

That being said, statistically, he is at high risk for re-injury, according to the research.

A study published in Arthroscopy in 2005 found that 12% of patients re-injure their same knee or injure their other knee in the first five years following surgery. Another study published in the British Journal of Sports Medicine 2006 found that soccer players with a previous ACL reconstruction had at least four times the risk of re-injury or injuring their other knee. Numerous research articles show continued deficits in strength and lower extremity control that can persist for years following ACL reconstruction. If you've followed ACL injuries in professional athletes, not everyone recovers as quickly as Adrian Peterson. Many end up like Derrick Rose and RG III.

An article published in Orthopedics 2014 by Erickson titled "Performance and Return-to-Sport After ACL Reconstruction in NFL Quarterbacks" looked at 13 NFL quarterbacks who underwent ACL reconstruction. They concluded that there is a high rate of return to sport in the NFL for quarterbacks and that performance was not significantly different from pre-injury. Another study published in the American Journal of Sports Medicine in 2010 found that only 63% of NFL players returned to play in approximately 11 months after surgery. More experienced and established athletes are more likely to return to competition at the same level than those with less professional experience. Being selected in the first 4 rounds of the NFL draft was highly predictive of return to play (Bradford was the number 1 pick in 2010).

An article published in the American Journal of Sports Medicine in 2009 showed that a history of meniscus surgery, but not ACL reconstruction shortens the expected career in NFL players. They also concluded that a combination of ACL reconstruction and meniscus surgery might be more detrimental to an athlete's durability than either surgery alone.

There is a high rate of re-injury or injury to the other knee in patients following ACL reconstruction. NFL players in general show about a 63% return to play after ACL reconstruction. However, quarterbacks showed not only a high rate of return to play but a return to previous levels of performance. That said, we don't know for sure if other structures were injured in the knee that could affect his return to play. From a research standpoint, the odds are in Bradford's favor to be back to the player he was prior to his injuries. But the question to be answered is, will he be AP or RG III?

Read more Sports Doc for Sports Medicine and Fitness.