February 23, 2011

Collateral Damage

To Each According to His Knee

by Corey Dawkins and Marc Normandin

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Knees are the topic du jour, it seems, with a formerly elite player recovering from knee surgery, one of the league's rising stars coming back from his own, and an established powerhouse behind the plate doing his best to stay in the game as often as he can in spite of the pesky joint. Knee injuries come in different shapes and sizes and require vastly different treatments, so we’ll examine each case in some detail below.

Grady Sizemore, CLE (Left knee surgery)

Sizemore underwent microfracture surgery on his knee in June of 2010 for an injury that was initially reported as a bone bruise. The bone bruise was real, but it was caused by a different injury: Sizemore had a chondral (cartilage) defect on the back of his left patella, which produced the bone bruise (although chondral defects do not always have that effect).

Microfracture is one technique used to address these chondral injuries. The procedure has been around for more than 20 years, but recently more professional athletes have been undergoing this surgical technique to “repair” damaged cartilage. Usually performed arthroscopically, it involves debriding (or cleaning) damaged tissue, removing any loose bodies, and ensuring that the surface is suitable for microfracture surgery. This particular type of cartilage is different from that of the meniscus or labrum; it is just like the white parts on the end of chicken bones, and most likely would be just as disgusting were you to chomp down on it during dinner. Once the surface is prepared, little holes are poked to produce bleeding and to form a clot in the defect. This clot then (hopefully) conforms to the entire area and over time transforms into a substance similar to articular cartilage, but will never be exactly the same as the original article.

What separates Sizemore's case from most isn't the microfracture surgery, it's where the microfracture was performed. Most cases of microfracture in the knee usually involve the weight-bearing parts of the femur called the femoral condyles. These are the two knobs, for lack of a better word, on the end of the thigh bone. Sizemore's procedure was on the back edge of his patella. The location is important because of the different functions of those structures. An injury to the femoral condyles is aggravated by weight-bearing motions, while patellar chondral injuries are more symptomatic with quadriceps activity, blunt force, and flexing the knee. Every step, every slide, and every jump in the outfield pushes on the area, and the pressure is multiplied when the knee is flexed.

The best way to prevent further injury is to undergo proper rehabilitation to give the clot time to transform into a smooth surface. Patellar stabilization braces may be somewhat beneficial depending on whether the cause of the injury is patellar instability; otherwise, they are not very useful. Another type of brace, called an unloader brace, is beneficial for injuries that occur in the weight-bearing surfaces of the knee. Sizemore’s surgery is nearly eight months behind him, so he and the Indians gave themselves every opportunity to avoid destroying the clot by being overaggressive with his return. This slow progression means that Sizemore won't require a brace for stability or unloading of the weight-bearing surface, but he may use one to cushion his kneecap when impacting the ground, wall, or other players.

Sizemore will likely lack the same quick burst of speed that made him a special player in the past, even all this time after surgery. His pain may be gone but his range in the outfield could suffer, and his work on the basepaths could follow suit. The best way to evaluate his knee—short of looking at it—is to see how aggressive he is. If he's aggressive in the outfield or on the bases, it means he trusts the knee. If not, the knee may not be 100 percent.

Joe Mauer, MIN (Left knee injections)

The one thing we've been hearing for years is that Mauer's knee won't be able to hold up behind the plate due to his size. Hearing that he recently completed viscosupplementation injections isn't going to put those fears to rest. These injections can be thought of as an oil change for humans and are different from cortisone injections. Used to counter the effects of degenerative changes, they may simply be part of a proactive pre-season plan on the part of the Twins to make sure Mauer's knee holds up.

There is no reason to use them in a fully healthy knee, though. The injury database shows that Mauer has had surgery on the knee twice, once in 2004 for a medial meniscus tear, and more recently this offseason on the plica, a band of connective tissue surrounding the kneecap that can become inflamed and cause painful clicking.

The Twins are trying everything they can to keep him behind the plate, but it's becoming clearer with time that these issues will force a move to DH or 1B at some point in the future. Justin Morneau is signed through 2013, so the Twins will have to hope that Mauer can hold up at least that long as a backstop.

Carlos Santana, CLE (Left knee surgery)

Santana is recovering from August surgery on the lateral collateral ligament (LCL) and looks to be ready for the Indians' first spring training game on February 24. The LCL helps to stabilize the outside part of the knee from forces that are applied to the inside part of the knee, as in the case of a catcher blocking the plate (unless those forces are equal to or greater in strength than Ryan Kalish).

The LCL itself is a rather small ligament, rope-like in nature, and it is very rarely injured in isolation. Instead, it is typically injured in combination with other knee-related acronyms such as the ACL, PCL, menisci, or even the hamstring tendons. Santana’s injury was not as bad as it could have been, given the normal associative damages, and his rehabilitation has gone according to plan. He is now catching bullpen sessions without any difficulties, and although he seems to be out of the woods, he will likely wear a brace as a precaution upon returning.

Nick Punto, SLN (Sports hernia surgery)

Initially thought to be suffering from groin soreness, Punto was sent for further evaluation. It turns out that he requires surgery for a sports hernia that will keep him out for roughly 8-12 weeks. The scientific way of explaining a sports hernia is to say that it is muscular weakness in the abdominal wall in the same area as traditional inguinal hernias. The inflammation causes pain, but there is no palpable protrusion. The lay-person way of explaining a sports hernia is to describe it as pain in your lower abdomen and groin when you attempt something physically strenuous involving those muscles. The pain becomes chronic and is often misdiagnosed, but that doesn't appear to be the case here.

The surgical procedure depends on the exact cause and full scope of the symptoms, but it could involve releasing one of the groin tendons (which you can refer to it as the much less cringe-inducing adductor longus), the inguinal nerve may be removed, and the oblique muscles could be repaired. Don't expect Punto back before May at the very earliest according to comparisons from the database, a list that includes Magglio Ordonez (2005, 79 days lost) and Ian Kinsler (2008, 42 days lost).

Scott Podsednik, TOR (Plantar Fasciitis)

Podsednik is dealing with plantar fasciitis again after missing the last month of the 2010 season due to this painful condition. The plantar fascia is a thick band of tissue that fans out across the bottom of your foot starting at the heel and ending near the base of your toes. There is no definitive evidence that links plantar fasciitis to any particular foot type, but it is certainly linked to a tight Achilles. Often most painful in the morning or after being on your feet all day, plantar fasciitis sufferers tend to feel better for a few hours in the morning and progressively worsen throughout the afternoon and evening. Every step can feel like a sharp, searing, almost burning pain, and when the tissue is inflamed it affects the player’s performance (unless that player is Albert Pujols, who apparently has no such Achilles Heel). There is a tendency for recurrence, but plantar fasciitis usually responds to conservative treatment. If it does require surgery, the plantar fascia can be released. For a speedster like Podsednik, this is even more of an issue, as he relies on his lower extremities to make a living—at least until science makes it possible to bottle and sell grit under the label "Eau du Pods".

Fabio Castillo, TEX (Left Foot Stress Fracture)

Stress fractures can be a tricky thing to get under control, but they almost always heal without surgery. Discontinuing the offending activity is the key. Stress fractures are not exclusive to the lower extremities, as young pitchers can get them in their spines or throwing arms. Once the bone is healed, Castillo will transition back into a full exercise and baseball training regimen and gradually return to pitching. Barring any underlying metabolic disorder which reveals itself after repeated fractures or stress fractures, an ailment like this can be managed with focused rehabilitation, but Castillo is still likely a few weeks away from a full bullpen session.

Flesh Wounds: Ryan Westmoreland has made incredible progress from brain surgery for a cavernous malformation and has been hitting in camp. He's scheduled for follow-up evaluation with the neurologist this week… Eric Hurley suffered a mild right hamstring strain and will be down for a few days… Travis Snider suffered a strained left intercostal muscle (small muscles in between the ribs) last week and just began taking soft grounders Tuesday with the goal of hitting off a tee later on this week... Jose Ascanio felt some tightness in his elbow Tuesday. He's coming back from labrum surgery performed in 2009. The Pirates will move him slowly, mindful of a possible cascade effect… The story of ASU's Cory Hahn reminds us that baseball carries tremendous risks and that catastrophe can strike on any play. We wish him a full recovery.

Corey Dawkins is an author of Baseball Prospectus. Follow @CoreyDawkinsBP
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