By Abby Sims
» More Columns

CC Sabathia, on the DL with what had been diagnosed as inflammation in his right knee, now has a real diagnosis, and it is degenerative changes to the articular cartilage. Media reports did not disclose the degree of wearing of the cartilage, a factor that is crucial to understanding the pitcher’s condition.

Sabathia was slated to receive a cortisone injection and treatment with stem cells. Cortisone is simply a steroidal anti-inflammatory that may reduce the signs and symptoms, but it has no curative benefit for the cartilage itself. Though worth a try, there is no guarantee that the stem-cell procedure will be successful.

A last-resort surgical option, should the current plan not succeed, is microfracture surgery, though this also offers no certain outcome.

Let’s backtrack a moment, though…

You may recall from my previous post that articular cartilage provides a smooth glassy surfacing at the ends of many bones. It facilitates movement while also protecting the integrity of the bones.

Though injuries to the articular cartilage — also known as chondral defects — often occur due to direct trauma that entails a rotational component, they may also result from degenerative changes. However, there are often factors that are predictive of the wear and tear that ultimately occurs.

Initial insults to the cartilage from prior injury — such as that causing the meniscal damage Sabathia suffered in 2010 — might have played a role in predisposing his cartilage to break down. The presence of any instability of the knee joint (such as that due to ligament sprains or tears) — especially coupled with overuse — also predisposes to the onset of degenerative changes, as does removal of a meniscus.

The degree of damage to articular cartilage is classified from zero, being normal cartilage, to Grade 4, which is when the surface is totally worn away, exposing the bone below. Grade 4 lesions are often described as being “full thickness” resulting in a joint being “bone on bone.”

Injury to the articular cartilage most often occurs in weight-bearing sections of the bone and on the medial (inner) aspect of the knee. Restoring articular cartilage is a tough order. Due to its poor blood supply — much like the menisci in the knee — it does not heal in the way most of our other tissues generally do. Microfracture surgery attempts to remedy this by perforating subchondral bone in regions that are cartilage deficient in order to stimulate a sustained reparative response by bringing blood to the region.

As for rehab, maximizing strength in the muscles crossing the hip and knee is crucial when addressing any knee issue. Strong muscles help to take some of the stress off the affected joints. Regardless of the specific treatment he receives, Sabathia will continue to work to optimize his strength.

It should be noted that as a lefty, Sabathia puts a lot of weight, force and torque on his right knee when pitching. Studies have shown that extending the lead knee “may provide stabilization, allowing better energy transfer from the trunk to the throwing arm, and could be a critical factor in pitch velocity.”

I would expect Sabathia to be out of action for longer than the 15 days dictated by his being on the DL. If he comes back right when he’s eligible, he’ll certainly not yet be at 100 percent and his velocity will likely be an issue.

Follow Abby on Twitter @abcsims.

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