Two words that inspire fear in any NBA fan: Plantar fasciitis.

Rajon Rondo now has a minor case of the foot ailment. My initial one-word reaction has four letters and sounds a lot like “puck,” but I also realized I didn’t know enough about the injury.

Rondo was in bad enough shape yesterday that trainer Ed Lacerte recommended he sit the game out. Of course, Rondo played and played pretty well. Yet Lacerte’s caution was telling.

Plantar fasciitis is probably most known because of Tim Duncan’s high-profile struggles with it, but the injury is actually quite common among NBA players. It causes “stabbing” pain to the heal and sometimes the arch, and the pain is especially bad during a person’s first few steps in the morning or after sitting for awhile — the discomfort is often alleviated after regular movement.

The pain is caused by excessive pounding on the foot. The foot absorbs up to five times a body’s weight when running, and even more than that when jumping. NBA players obviously spend a lot of time running and jumping, so the amount of stress an NBA player’s foot receives is far more than the average foot. NBA players often contract plantar fasciitis at the beginning of the season, when a body is not used to the daily grind of an NBA schedule.

Once an individual is diagnosed with plantar fasciitis, he normally starts treatment by ingesting Motrin, Ibuprofen, Naprosyn or Celebrex. These oral medicines serve to slow the foot’s inflammation. Another treatment can be the injection of short and long acting steroids. While they sometimes have side effects, steroids can help to lessen (or in some cases eliminate) symptoms.

Besides medicinal treatment, plantar fasciitis patients can often benefit from other methods. Stretching programs have often worked, and even small changes like a shoe change or a taped foot can help. Many basketball players are also fitted with orthotic shoe inserts. Rest can also be utilized for the foot, and night splints can be helpful. If none of the preceding treatment works, surgery is normally the last option. According to the Mayo Clinic, “about 90 percent of the people who have plantar fasciitis recover with conservative treatments in just a few months.”

As I noted earlier, the Spurs (and mostly Tim Duncan) helped bring fame to plantar fasciitis. Kendrick Perkins has also battled the ailment, especially earlier in his career, and Shaq has dealt with the injury at some points of his career. But perhaps Duncan’s teammate Tony Parker — a similarly speed-based point guard — is a better comparison to Rondo. Parker experienced a bout with the foot ailment last season, and partially blamed it for his drop in production. The French point guard’s averages fell from 22.0 ppg and 6.9 apg in 2008-’09 to 16.0 ppg and 5.7 apg in ’09-’10. When asked in January why his drives to the basket seemed less explosive than usual, Parker responded, ““I’m a little bit slower, that’s why. I don’t think it’s much different. It’s just my plantar fasciitis is killing me.” Parker mostly played through the pain, but wore a sock designed to limit the symptoms of the injury.

So far, at least, Rondo doesn’t seem to be feeling quite the same amount of pain as Parker experienced. The Celtics labeled his case “minor” and Rondo’s play clearly hasn’t suffered. Doc Rivers admitted that he could tell Rondo felt pain at one point in last night’s first quarter, but I personally didn’t notice any limping or wincing. From where I was sitting, Rondo looked to be playing just like he normally does. Like a bolt of lightning.

Plantar fasciitis, to NBA fans, is a scary term. Before today, I was mostly uneducated about it. Thanks (no thanks?) to Rajon Rondo, I am now a faux expert. And the injury? Though it’s not as scary as I initially expected, it’s certainly a cause for concern.