As I’ve blogged before, one of the hottest trends in orthopedics today is selling younger and active patients on knee replacement. There’s an ad campaign going on right now in the area where I practice that’s specifically focused on this under-55 crowd by showing patients mountain biking, rock climbing, skiing, and distance running. What if the research on this approach of replacing young knees showed the opposite? I recently blogged on a study that highlighted that knee replacement in younger patients is not that successful. Now a new study again shows high dissatisfaction rates in young knee replacement patients.

Why Knee Replacement Is Risky

A knee replacement is a highly invasive surgery in which the surgeon amputates the knee joint and inserts a prosthetic, or an artificial, joint. This involves cutting off the ends of the two long leg bones (femur and tibia) that form the knee as well as removing the structures that live inside the joint (e.g., ACL, PCL, cartilage). Following this, the prosthesis, typically a metal device, will be drilled into the severed bones, Usually, there’s a plastic or ceramic layer which serves as artificial cartilage between the metal joint components. As you can imagine, this is a serious surgery that carries many risks, which I’ve covered before, but this list keeps getting longer and longer. Let’s review some of these.

Pain and Function

Pain can be an especially disturbing result after a knee replacement because most patients who make the decision to get a knee replacement do so because of knee pain. So when the pain is still there following this extreme surgery, you might have questions: Was it all really necessary? Why hasn’t the surgery stopped my pain? Will my knee pain eventually subside, or will it just get worse? Unfortunately, the answers aren’t promising:

• The most common complaint following knee replacement is ongoing knee pain.

• Pain rates tend to get worse as time goes on—studies show two, three, even four years following knee replacements.
• Knee pain could be due an issue in your back and may have never been due to a knee issue at all.
• Knee pain could be due to a loose ligament, and, again, not the joint itself.

What about function? Maybe, at least, my activity levels will improve. After all, that’s what the ads promise. Not likely. Only 1 in 20 knee replacement patients are able to eventually function at normal, healthy activity levels. And as I mentioned in the first paragraph, young knee replacement patients, those who have the surgery early, are prone to more pain and to wearing out the joint faster.

Allergies

Surgery aside, the artificial joint in and of itself is simply not safe. The average lifespan of a knee-joint prosthetic is 15 years, and with wear and tear, the knee-replacement device can shed metal particles, causing ions to build up in the blood. In addition, if you already have allergies to metals, such as certain types of materials used in jewelry, this increases the risk that you will be allergic to the metal knee device. Interestingly, studies have shown that if you are just someone who is prone to allergies in general (e.g., pet dander, seasonal, skin allergies, etc.), you are more likely to have allergic reactions to these knee replacement devices—it doesn’t have to be a metal allergy. Artificial knees made with other materials don’t fare much better. For example, patients can also experience allergies to the new plastics used in these joint prostheses.

Other Knee Replacement Risks

In July of this year, I shared a study with you showing an increased risk of spinal fractures following knee replacement. The same study also showed that within 10 years following a knee replacement, there is an increased risk of hip fractures. And another study category that I’ve covered numerous times on this blog is the severe risk of heart attack, stroke, and blood clots associated with knee replacements

Do We Know That Knee Replacement Is Effective?

You would think that based on the riskiness of this procedure and the tens of billions spent every year, we would have solid data that this procedure works well to reduce pain and increase activity. In fact, we only have a single high-level study that was recently performed. Note that the study found lackluster results. As an example, you have to amputate 5–6 knees and insert a prosthesis to get one patient who reports more than a 15% functional improvement! Ouch! See the video for more details on that study.

The New Research on the Low Rates of Satisfaction in Young Knee Replacement Patients

The new study looked at 177 subjects under the age of 55 who’d received total knee replacements. The factors researchers considered included gender; BMI; range of movement; and the subjects’ Kellgren Lawrence (KL) grade, which measures the severity of arthritis present. Results showed that 25% of these subjects were “unsure or dissatisfied with their knee” at one year following surgery. Even more concerning, of those with KL grades 1/2 (mild to moderate arthritis), 59% were dissatisfied. This is one of the more common trends we see today: surgeons offering patients who only have moderate arthritis a knee replacement; hence, all those ads targeting younger patients.

The study concluded, “Patients receiving TKA younger than 55 years old should be informed about the increased risks of dissatisfaction. Offering TKA in KL 1/2 is questionable, with a dissatisfaction rate of 59%.”

The upshot? Knee replacement is a huge procedure that involves cutting off the end of long bones. It is not to be taken lightly. So pushing this procedure on younger and younger patients is a serious issue, especially when the data shows that most of these young knee replacement patients aren’t really going to be happily riding their bikes, skiing, and climbing mountains!