Advancements in Knee Replacement

Dr. Daniel K. Witmer

Dr. Daniel Witmer is a leading orthopedic surgeon who specializes in joint replacement of the hips and knees. During his fellowship at Indiana University, he was trained in complex hip and knee replacement and revision surgery, computer-assisted surgery, cementless and partial knee replacement, and rapid recovery techniques enabling outpatient joint replacement for optimized patient recovery.

Dr. Witmer’s clinical interests include cementless knee technology, joint kinematics, computer-assisted and robotic surgery, and treating fractures and complex problems around existing hip and knee replacements. 

Below he discusses some of the newest advancements in knee replacement.

Who is the ideal candidate for a knee replacement?

Knee replacement is one of the most common procedures performed in the United States today. Many patients are going into their 50’s, 60’s, and 70’s expecting to be able to stay active, and joint replacement is one of the tools that allows them to do that. Knee osteoarthritis can be a severely disabling condition if not properly managed. About 600,000 total knee replacements are performed every year in the U.S., and by 2030 we expect that number to be closer to 1 million per year. To meet this demand and to match patient expectations, we are guiding joint replacement to high volume centers like the Bone and Joint Institute. Studies have conclusively shown that the more joint replacement procedures a surgeon or a hospital does, the better the outcomes are for the patient.

Ideal candidates for joint replacement are patients who have significant knee arthritis whose daily activities such as walking, hiking, biking, or even just going to the store are limited due to knee pain. We have several non-operative treatments that work for many patients as well, which we always prefer over surgery. These include therapy, injections, bracing, and medications for anti-inflammation. Once these therapies fail, however, patients are indicated for joint replacement surgery. Patients who are not candidates for surgery are patients who are very overweight (BMI>45), smokers, and those with poorly controlled medical conditions such as diabetes. These patients are at high risk of infection after surgery. We have a great program at the Bone and Joint Institute called the MODIFY program which includes a nutritionist and therapist who can guide patients on a weight loss journey or to quit smoking and get ready for their needed operations.

When is a partial vs. full knee replacement recommended?

The knee has three compartments inside of it, and we evaluate how much cartilage is lost from each to determine if someone is a candidate for a partial vs. total knee replacement. If only one compartment has cartilage loss, that patient may be a candidate for a partial knee replacement. Partial knees are good because the recovery is quicker (2-3 weeks vs. 6-8 weeks for a total knee), and the joint is more natural feeling. The downside of partial knees is that the rest of the knee can develop arthritis over time and eventually need to be converted to a total knee replacement. However, in the properly selected patient, this is rare.

What is “cementless” knee technology? How has this dramatically changed the knee replacement process?

During a knee replacement procedure, the damaged portions of the knee joint are removed and the joint is resurfaced with prosthetic components.

Traditionally, the metal prosthetics were held in place with bone cement. However, advances in implant technology have led to knee implants that do not need to be cemented into place. Instead, the textured surface of the implant encourages bone growth, so the implant is rigidly fixed to the bone. Both cemented and cementless knee implants are currently used for knee replacements, depending on the needs of the patient.

Cementless knee implants have a rough, porous surface that encourages new bone growth. The new bone grows into the spaces in the implant, holding it in place without the need for cement. The bones within the knee are shaped with special tools so that they fit snugly with the implant. In some cases, screws or pegs may be used to hold the prosthetics in place while the bone grows. Cementless technology is what we have been using in hip replacements for many years. Because of the complex anatomy and joint mechanics of the knee, older cementless implants did not work as well. Current designs, however, have an outstanding clinical track record now with almost 10 years of follow-up.

The advantage of cementless implants is that patients don’t have to worry about potential complications from cement breakdown in the long term. This was traditionally an area that broke down after 20 or 25 years from the time of surgery. Given that we are performing many knee replacements on patients in their 50’s and 60’s, we believe that using cementless technology on these select patients will increase the longevity of their joints in the long term.

What can people who have a knee replacement expect in terms of time off from work? The surgery? The recovery process? Pain?

I like to treat patients very individually when it comes to returning to activities and work. A 65-year-old accountant who likes to walk is going to return to work sooner than a 55-year-old construction worker who lifts 100 pounds on the job every day. In general, people who do not do heavy labor can return to work in around 6-8 weeks. People who do a lot of lifting and activity at work usually take 10-12 weeks to return full time. The recovery process after a knee replacement is highly dependent on physical therapy. A good physical therapist is key, and our therapists in the Hartford network as well as at Orthopedic Associates are really the best. They communicate with the surgeon regarding the patient’s progress and help the patient regain strength and mobility while decreasing pain.

Early in the recovery process, icing the knee and elevating the knee to reduce swelling are key. We now use multiple different medications for pain so that we do not need to use opioid pain medications as much. Our patients are coming out of surgery and into the first few weeks with much fewer side effects due to this approach. New anesthesia techniques as well as nerve blocks are also critical in early recovery and have dramatically improved, even over the past 5 years.

If someone suffers from knee pain, when should he/she consider a replacement? What is the first step?

The first step to take if you are suffering from knee pain is to have your knee evaluated by an orthopedic specialist. Once the knee is hurting for more than a few weeks, and over the counter pain medications are not helping, it is time to get it checked out. Seeing your orthopedist is convenient and cost-effective. The reason for this is that in one visit, you can be diagnosed and treated without having to see another provider in a few weeks. Frequently we can make our diagnosis by X-rays and physical exams alone, so more advanced testing is not always needed. If it is needed, this can be done expeditiously. Your questions and concerns will be answered, and a treatment plan that is individualized to your needs can be put into place.

Dr. Witmer sees patients in Farmington, Glastonbury, Rocky Hill, Hartford, and Plainville. Call (860) 549-8267 to schedule a visit.