Sims: Brutal News For Scott Sizemore; What Now After Repeat ACL Tear?

By Abby Sims
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Oakland A's infielder Scott Sizemore will be sitting out a second consecutive season because of impending left ACL (anterior cruciate ligament) surgery. After complaining of stiffness in his knee last night, it was determined that Sizemore had re-torn the ACL he'd first injured last spring. After an arduous rehab that was reportedly uneventful and free of setbacks, he will have to do it all over.

Again.

This will be the third time Sizemore visits the operating room in his short career. In 2009, after being named Detroit's minor league player of the year, he underwent surgery to repair a left ankle fracture suffered in Fall League play.

The ACL

The Anterior Cruciate Ligament is the primary stabilizer of the knee. It is called the anterior (front) cruciate because it crosses another ligament (the posterior cruciate) that is located behind it. Both ligaments essentially form an "X" connecting the femur of the thigh to the tibia of the lower leg. The role of the ACL is to prevent the top of the tibia from excessively rotating and from gliding forward, limiting hyperextension of the knee. When torn, these motions are not sufficiently checked and the knee becomes unstable, often buckling.

Sizemore's Repeat Performance

Interestingly, studies have shown that, on average, new ACL injuries following prior ACL reconstruction are twice as common on the opposite knee as on the surgical side. The risk was shown to be 1.8 to 10.4 percent (or an average of 5.8 percent) on the post-op side versus 8.2 to 16 percent (an average of 11.8 percent) on the opposite limb. There are several reasons suggested as to why this may be the case – insufficient attention to the unaffected side in the rehab program, or over-reliance on the unaffected limb are thought to be primary. Neither explains Sizemore's circumstance.

Many studies have been done to assess and compare the various techniques of ACL reconstruction and their post-operative outcomes. Not all the findings are in agreement. Sizemore's ligament was replaced in 2012 with a graft taken from his (outer) hamstring tendons. Hamstring grafts are generally found to be even stronger than grafts taken from the patellar tendon that are secured with bony plugs. However, much research has concluded that hamstring grafts are not as stiff, resulting in a slight increase in laxity of the knee joint. I did not come across studies of this nature performed strictly on a pro athlete population to determine whether this difference has a significant impact on post-operative participation in sports at an elite level. In the general population it is not thought to do so.

Though there is risk of complication following any surgery, recovery from ACL reconstruction with hamstring grafts is not as likely to be impacted by pain and pathology at the patellofemoral area (the kneecap). However, a loss of hamstring strength can persist for up to a year. In contrast, patellar tendon grafts can result in diminished strength of the extensors and occasionally a loss of full mobility into extension. Early and appropriate rehab intervention, as well as compliance with treatment limits complications. Though the patellar tendon is still used more often as a graft, the hamstrings may be the option of choice, especially if a patient has had patellofemoral issues in the past or had prior surgery using the patellar tendon. In either case, the tendons that served as the source of the harvested grafts repair over time. Rehab must progress cautiously to avoid overuse as they heal.

So, what now for Sizemore? It is likely that he will have a patellar tendon graft taken from either his left or right leg.  Doctors are unlikely to go back to the source of the earlier graft. An alternative would be a graft taken from a cadaver (referred to as an allograft). Here's wishing Scott Sizemore much fortitude and luck in his efforts to make it back and stay healthy in 2014.

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