Portland sports fans could not have been happy this week. The NBA's No. 1 draft pick is expected to miss the entire 2007-08 season because of a problem with this knee.

Portland Trail Blazers brand new 7-foot-tall rookie center Greg Oden, in his blog, said he felt a "sharp pain" in his right knee about a month ago as he got off a couch. It was all downhill from there.

He recently underwent arthroscopic surgery and that the time of surgery some damage was found on the joint surface requiring a procedure called "microfracture."

A microfracture surgery is usually needed when an area of the damage is noted on the joint surface that goes down to bone. These are called chondral defects and are extremely common.

As an orthopedic surgeon who specializes in the knee, I routinely see several per week in my practice. They are easily seen during arthroscopy, but are sometimes difficult to diagnose in the office, even with high-tech MRI scans.

They usually do not show on x-rays. Greg Oden actually had, according to reports, normal MRI scans of both knees as part of the pre-draft medical evaluation. Every June, as part of the NBA combines, all NBA draft prospects go through an intense screening process that includes both medical and orthopedic exams.

MRI scans are wonderful in many ways and are quite helpful in diagnosing certain the conditions like a torn cartilage or meniscus, or torn ligaments, or even fractures that don't show on x-rays.

However, they are not always great at showing the joint surface or cushion, especially small areas of damage. MRI technology is improving in this capacity but is not yet perfect.

Every joint in your body has a cushion called articular cartilage. When this cushion begins to wear out, it is arthritis. Chondral defects are different in that they are more localized areas of damage rather than the extensive wear that is usually seen with arthritis.

Some individuals will get a focal area of damage to the joint surface (similar to a "pothole" on an otherwise well paved street or highway). These defects, when they are deep, or down to bone, require treatment especially if the patient is young and/or active.

The goal is to try to re-grow and restore a normal joint surface or cushion. This is a major challenge because normally your joint surface or articular cartilage has very limited healing capabilities - and does not on its own repair itself or re-grow at all. Unfortunately if the chondral defect is significant, and not treated, especially in an individual who remains active, it will progress to arthritis. The knee is then doomed.

There are several surgical techniques to try to re-grow a joint cushion. The most common is the "microfracture" technique. Microfracture is a relatively simple outpatient surgery done under anesthesia.

The area of damage is identified and small puncture holes (vascular channels) are placed in the exposed bone after the defect is prepared with a gentle scraping technique using a currette.

There are specialized surgical awls that make the puncture holes or "microfracture" very precise. A clot then forms in the defect which contains your body's own stem type cells. Over the next six months to two years, if all goes well, your body will slowly form a new joint cushion in this area. Unfortunately, the tissue is not quite as good as the one you were born with, and durability of this tissue can be an issue. Not great news for a professional athlete.

The hardest part about microfracture surgery is not really the surgery itself. Most of my patients who have had microfracture surgery tell me that the surgery was a breeze. The hard part is the pretty restrictive postoperative precautions including the need to be on crutches usually for six to eight weeks, and the requirement to remain out of any high-impact activities for at least four to six months - sometimes longer. It's not a painful recovery - it's one that test the patience of the patients.

In my next blog entry I will cover more about the postoperative recovery and protocols for individuals who have had microfracture surgery.

I'll also share the a longer-term results of these types of procedures as well as some newer and even futuristic approaches for dealing with these troublesome knee joint "potholes".

Have you had a microfracture or similar surgery? What was your experience? How were your results? Would you do it again? Please share your experiences.