Dr. Ronald Grelsamer, the chief of patellofemoral reconstruction at Mount Sinai Medical Center.

The specialist: Dr. Ronald Grelsamer, orthopedic surgery

As the chief of patellofemoral reconstruction at Mount Sinai Medical Center, Dr. Ronald Grelsamer is an orthopedic surgeon who specializes in knee pain and surgery. His particular expertise is the kneecap, or patella.

Who’s at risk

Every year, about 500,000 Americans require a knee replacement. About 5% of them may be candidates for a smaller, more focused surgery.

“A type of partial knee replacement, called a patellofemoral replacement, is an option for patients with kneecap arthritis,” says Grelsamer. “It’s a partial knee replacement that replaces only the kneecap and the underlying femoral groove, leaving all the healthy structures of the knee intact.”

The kneecap is a bone with a thick undersurface of cartilage. “The kneecap glides within a groove, and that groove also has cartilage,” says Grelsamer. “The cartilage is durable, but like the brakes in your car, it can wear down.”

When the undersurface of the kneecap wears out – a condition called patellofemoral arthritis – patients may benefit from a patellofemoral replacement.

“For some people, kneecap arthritis is just a matter of their DNA,” says Grelsamer.

“But another risk factor is weight – because your kneecap sees many times your body weight when you go up steps or get up from a low chair.”

Other causes of extra wear and tear include trauma, anatomic variations – the knee’s version of hip dysplasia – and certain exercises, like squats and deep knee bends.

Signs and symptoms

The red flags of kneecap arthritis are mostly localized at the front of the knee.

“The classic symptom is persistent pain at the front of the knee, often experienced as a painful catching or locking sensation,” says Dr. Grelsamer. “Patients will rub their knuckles together and say, ‘It feels like this.'”

Common triggers for knee pain include climbing stairs, getting up from a low chair or sitting with the knee bent for long periods of time, for instance at a movie theater or on a plane.

If your pain gradually becomes resistant to over-the-counter medications, this is a sign that the arthritis is progressing.

“Like arthritis anywhere in the body, kneecap arthritis has the potential to cause unrelenting pain,” says Grelsamer.

Traditional treatment

Most patients start out by trying to rein in their chronic knee arthritis with nonsurgical approaches varying from behavior modification and medications to injections.

“One of the first things to do is avoid the things that hurt, like going up or down big steps when there’s an elevator option,” says Grelsamer.