(www.mendmyknee.com)

Vikings fans breathed a collective sigh of relief when Adrian Peterson was cleared to practice recently.  Steelers fans were confused and surprised when Rashard Mendenhall was removed from the PUP list last week.  Both were recovering from surgery to repair — it’s actually a reconstruction — a torn anterior cruciate ligament (ACL).  Also cleared to practice were Steelers nose tackle Casey Hampton and LT Max Starks, who sustained similar injuries in the Wild Card round playoff loss to the Broncos last January.

Now the obvious question is: are they coming back too soon?  Professional athletes are trained to push hard and minimize their injury time.  One Hall of Famer thinks Peterson should take more time; 49ers legend Jerry Rice returned 111 days (less than 4 months) after his ACL repair and promptly broke his patella (knee cap)  in the same knee. He has publicly cautioned against Peterson’s seemingly rapid return.

One factor to consider is that Peterson had repairs to both his ACL and his MCL, which requires a longer recovery than an ACL repair alone.  In addition, more than 60% of ACL injuries are associated with a meniscal tear.  Adding a repair of the meniscus, the cushion between the bones of the joint, has been shown to lengthen recovery according to a study published by the American Academy of Orthopaedic Surgeons.  Rice had both repaired as well.  When he announced his return to the field after a mere 17 weeks, a number of my orthopaedic colleagues actually predicted that he would suffer a pateller fracture.  It typically takes a year for the body to incorporate the graft used for the repair, regardless as to whether it is a cadaver graft or an autograft harvested from the patient.  Without that strength from proper healing, the ligament is at high risk for another injury.

Another consideration is what kind of movement is necessary.  Obviously, a running back will place more stress and strain on his knee with cutting and pivots than an offensive lineman.  Steelers running back Baron Batch, who tore his ACL in the 2011 pre-season as a rookie, said he is just now finally feeling that he can trust his knee to hold up with every movement.  Patriots WR Wes Welker tore his ACL and MCL in January 2010 and worked hard to return for the following season.  A look at his stats over the past 5 years, however, clearly show that he wasn’t back to his usual form.  Even Tom Brady, a fairly immobile quarterback, required a year to recover from his ACL injury.

So is AP making a mistake returning 7 months post-op?  Only time will tell.  In the meantime, don’t expect to see the same old “All Day” until 2013.

Melanie Friedlander is a board-certified surgeon and a contributor to Aerys NFL.  You can follow her on twitter at www.twitter.com/girlsurgeon.