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Knee Arthritis Questions Answered by St. Luke’s Surgeon Dr. Robert Grob
July 15, 2020


Robert B. Grob, D.O., is an orthopedic surgeon who this Spring joined St. Luke’s Orthopedic Care specializing in treatment of the knee. Dr. Grob earned his medical degree from New York College of Osteopathic Medicine and completed his internship and residency at Philadelphia College of Osteopathic Medicine where he was able to work with numerous professional sports teams.

Research shows that approximately 20 percent of all people have some type of knee arthritis by the time they are 40, and that percentage goes up about 10 percent every additional year.

“I treat every patient as a member of my family,” he said. “This occurs as a result of practicing in the same community for nearly 20 years. In my two decades of treating patients from Carbon County and its adjacent counties, I have seen an entire generation grow and be leaders of this community. My success in joint reconstruction has been awarded with a Blue Cross Center of Joint Distinction, the first in the region.”

What is arthritis of the knee and why does it occur?

Dr. Grob: “It is a progressive degenerative condition. As we get older, the cartilage in the knee starts to soften up and thin out. It eventually causes radiological evidence of bone spurs, loss of joint space, and distinct changes in the bone. The knees are a weight-bearing joint, and approximately 4-6 times of our body weight gets distributed to the knees with every step.”

What are the symptoms of arthritis and other  wear and tear in the knee?

Dr. Grob: “The first and main one is pain. Other symptoms are an inability to walk, or walking less distance because of swelling. You take more frequent breaks. An example is two years ago you could walks four blocks, last year only two blocks, and this year one. It’s a decline in function.”

What are some conservative treatments and therapies for the knee?

Dr. Grob: “Weight loss and exercise are the two main things. Other modalities are over-the-counter anti-inflammatories like Tylenol, or prescription medications. The use of a cane or walker for the older population sometimes helps. We will often recommend physical therapy, which eventually transitions to a home exercise program. We will also offer injection therapy using cortisone or viscosupplementation, which is like changing the oil in your car.”

When is it time to recommend knee replacement?

Dr. Grob: “After you exhaust all conservative treatments and there is radiograph evidence of arthritis, bone spurs, loss of joint space, then it’s time to talk about surgery.

What is involved in knee replacement, from the surgery to recovery?

Dr. Grob: “It’s a multifactorial process that begins even before surgery. You need to complete lab tests to make sure there are no blood issues, such as anemia. If you are diabetic, you have to make sure your blood sugar is under control. You need to get medical clearance from your  family physician or internist. Once you get the green light for surgery, then you schedule. Surgery typically takes from one hour to one hour, 15 minutes. An incision is made in the front of the knee, all the diseased bone is removed and the artificial knee is inserted. The typical hospital stay is one to two nights. Most patients go home after one night, and physical therapy begins at home or on an outpatient basis right away. Patients use a cane or a walker, and as pain decreases and range of motion increases, cane and walker use can be minimized or eliminated. As long as you can bend the knee, straighten the knee and can walk on it, you are on the way to  successful recovery.” 

What is the importance of physical therapy in recovery?

Dr. Grob: “It helps ensure success. Physical therapy is important because newly operated muscle wants to shut down. Physical therapy helps patients regain their strength and range of motion and function as quickly and safely as possible.”  

How far have knee replacements come in the past 20 years?

Dr. Grob: “Knee replacements have been around for about 50 years. The procedure first started with patients in their 80s because we didn’t know how long they’d last. As the technology has improved over the decades, the biggest revolution has been in in the longevity of the bearing in the knee, which was one of the things that originally wore out. The bearing now lasts more than two decades. Other improvements include better tracking with the knee cap over the groove of the femur to make it easier to go up and down stairs. There are also knees made specifically for males and females because studies over the past two decades show there are anatomical differences. The shape of the bearing has changed as well to improve functionality.”

How long will a knee replacement last?

Dr. Grob: “In the past 20 years, I have never taken one out that’s worn itself out, so the success is greater than two decades. There are, however, unfortunate circumstances where a patient will need a revision surgery. There is also a small chance of infection – one-tenth of one percent – and rarely incidental loosening that requires revision surgery.”


Media Contact:

Sam Kennedy, Corporate Communications Director, 484-526-4134, samuel.kennedy@sluhn.org


About St. Luke’s

Founded in 1872, St. Luke’s University Health Network (SLUHN) is a fully integrated, regional, non-profit network of more than 16,000 employees providing services at 12 hospitals and 300+ outpatient sites.  With annual net revenue greater than $2 billion, the Network’s service area includes 11 counties: Lehigh, Northampton, Berks, Bucks, Carbon, Montgomery, Monroe, Schuylkill and Luzerne counties in Pennsylvania and Warren and Hunterdon counties in New Jersey.  Dedicated to advancing medical education, St. Luke’s is the preeminent teaching hospital in central-eastern Pennsylvania.  In partnership with Temple University, St. Luke’s created the Lehigh Valley’s first and only regional medical school campus.  It also operates the nation’s longest continuously operating School of Nursing, established in 1884, and 38 fully accredited graduate medical educational programs with 347 residents and fellows.  St. Luke’s is the only Lehigh Valley-based health care system with Medicare’s five- and four-star ratings (the highest) for quality, efficiency and patient satisfaction.  St. Luke’s is both a Leapfrog Group and Healthgrades Top Hospital and a Newsweek World’s Best Hospital.  In 2020, two of IBM Watson Health’s 100 Top Hospitals were St. Luke’s hospitals.  St. Luke’s University Hospital has earned the 100 Top Major Teaching Hospital designation from IBM Watson Health eight times total and six years in a row. St. Luke’s has also been cited by IBM Watson Health as a 50 Top Cardiovascular Program.  Utilizing the Epic electronic medical record (EMR) system for both inpatient and outpatient services, the Network is a multi-year recipient of the Most Wired award recognizing the breadth of the SLUHN’s information technology applications such as telehealth, online scheduling and online pricing information.  St. Luke’s is also recognized as one of the state’s lowest cost providers.