When trades and free-agent signings are announced, almost everyone dismisses the phrase "pending a physical" without much thought, yet Mike Napoli's diagnosis of avascular necrosis (AVN) reminds us that those physicals make up an important part of a contract.
Napoli and the Red Sox first agreed to a three-year, $39 million deal in December pending a physical. However, following his diagnosis, Napoli signed a revised one-year, $5 million deal on Jan. 22—a deal that also includes $8 million in potential incentive bonuses.
That means that Napoli has the same earning potential this year—$13 million—as his original deal would have provided for. That is likely no coincidence, and a brief review of avascular hip necrosis makes it clear why that is.
To start off, let's break down the meaning of the condition's name:
- "Avascular"—without blood supply
- "Hip"—hip (No tricks here!)
- "Necrosis"—cell death
In other words, AVN—also called osteonecrosis—is caused by decreased blood supply to the bone, leading to bone cell death. Why does that happen? In many cases, doctors never know—termed "idiopathic."
Yet, that is not to say the medical community doesn't know quite a bit about the condition, the same condition that ended Bo Jackson's career.
AVN can occur in any bone, but it most commonly occurs in areas of bone with only one route of blood supply. One such area of bone is the head of the femur—the thigh bone—as it inserts into the pelvis—making up the hip. Other areas without collateral blood supply include the humerus—the bone of the upper arm—and the talus—one of the bones of the ankle. If one of these bones' blood supply is interrupted, destroyed or blocked for any reason, AVN occurs.
Though the exact cause of AVN remains theoretical in many cases, a number of risk factors have been proposed and linked to the disease. They include:
- Repetitive trauma
- Repetitive weight-bearing exercise
- Previous fractures
- Steroid use
- High blood pressure
- Autoimmune diseases
- Underlying medical conditions predisposing to blood clots
At this point, identifying a cause for Napoli's AVN is purely speculation—something that cannot be stressed enough. However, one can't help but notice the link between Napoli playing primarily as a catcher for a portion of his career and the fact that the disease is in his hips.
That link likely played into Boston's decision to sign Napoli as a first baseman rather than as a catcher, suggested by Red Sox general manager Ben Cherington when he said (h/t Nick Cafardo):
For a couple reasons, we’re focusing right now on (first base). No. 1, because obviously that’s our primary team need and that’s where the biggest opening is. And No. 2, it makes sense in the short term to allow Mike to focus on that position, perhaps to take a bit of the load or a bit of the stress off the body — off his lower body in particular.
Perhaps years of crouching behind home plate placed too much stress on Napoli's hips—"squishing" his hip's blood vessels, if you will—and perhaps his hips were already predisposed to developing the disease. Maybe his AVN is due to another cause altogether. It is impossible to tell.
However, for whatever reason, bone is dying within Napoli's hips, a diagnosis made clear by his December MRI.
As bone cells die, they are broken down and absorbed by the body, leaving gaps in their place. Gaps in bone can lead to quickly progressing arthritis due to cartilage destruction, range of motion limitations and a propensity for fractures.
In the worst case scenario, destruction of subchondral bone—the bone at the very end of a long bone such as the femur—can lead to cracks in the bone and even small pieces of bone breaking off and moving within the joint, causing further damage—a condition called osteochondritis dissecans.
However, none of that is yet occurring with Napoli. As Cafardo also writes, Cherington said that Napoli's disease "has been caught very early and (is) a long ways from Bo Jackson."
That is the best news Napoli could hope for. In fact, Cafardo reports that according to his agent Brian Grieper, Napoli is currently asymptomatic. The progression of his disease will be monitored by Dr. Joseph Lane out of the Hospital for Special Surgery in New York.
Hopefully, that progression will be slow. However, if his AVN does, indeed, progress, Napoli's future salary and contracts will likely reflect the potential of decreased production, as the only definitive treatment for advanced AVN of the hip is a total hip replacement.
Whether or not he signs future deals on a year-to-year basis depending on the effects of his disease—or lack thereof—remains to be seen. That said, Napoli's $13 million 2013 earning potential being based mostly on incentive bonuses implies that the Red Sox are—for now—taking things day by day.
According to ESPNBoston.com, to increase his salary to $13 million, Napoli must be on the active roster for at least 165 days or 125 days with at least 625 plate appearances.
After all, the Red Sox are in need of a slugging first baseman after trading Adrian Gonzalez to the Los Angeles Dodgers last August. Though he batted only .227 last year, Napoli has hit at least 24 home runs in each of the past three seasons.
For the time being, his medical condition should not prevent him from doing so again in 2013.
Dave Siebert is a medical/injury Featured Columnist for Bleacher Report who will graduate from medical school in June. He plans to specialize in both Family Medicine and Primary Care (non-operative) sports Medicine. Injury and anatomical information discussed above is based on his own knowledge with supplementation by Medscape's article on avascular necrosis.