Your kneecap after knee replacement is usually still your own bone. Depending on the surgical approach, the underside may have been reshaped and covered with a plastic component, but the entire kneecap is not ordinarily removed.
This distinction explains why surgical reports may say that your patella was “resurfaced,” “retained,” or “not resurfaced.” Here is what those terms mean and how you can find out what was done during your surgery.
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What Happens to Your Kneecap During Knee Replacement?
Your patella, commonly called your kneecap, is a small bone located within the quadriceps tendon at the front of your knee. Its underside glides within a groove at the end of your femur as your knee bends and straightens.
During a conventional total knee replacement, the damaged surfaces at the end of your femur and the top of your tibia are reshaped and covered with implants. Your surgeon must also decide how to manage the joint surface on the underside of your patella.
There are two primary approaches. Your surgeon may leave the natural patellar surface in place, sometimes smoothing or removing irregular tissue. Alternatively, your surgeon may resurface it.
What Patellar Resurfacing Means
When your patella is resurfaced, a portion of bone and damaged cartilage is removed from its underside. A dome-shaped polyethylene component, sometimes called a patellar button, is then attached to the prepared surface.
The remaining bone, quadriceps tendon, and patellar tendon stay in place. The plastic component faces the femoral implant and cannot be felt through the skin on the front of your knee.
Although the procedure changes the joint surface, it does not ordinarily replace your entire kneecap. Your patella remains connected to the mechanism that allows you to straighten your knee.
A resurfaced kneecap is generally still your own bone with a new surface attached underneath it.
During surgery, the patella may be moved temporarily so the surgeon can access the joint. The details vary with the surgical technique, your anatomy, and the implant system being used.
Why Some Kneecaps Are Resurfaced and Others Are Not
Patellar resurfacing practices vary among surgeons, implant systems, countries, and individual cases. Some surgeons routinely resurface the patella. Others use selective resurfacing based on the condition and thickness of the bone, cartilage damage, alignment, and other surgical findings.
Research comparing resurfacing with nonresurfacing has produced mixed results. Some systematic reviews have found lower reoperation rates with resurfacing, while differences in pain, range of motion, function, and satisfaction have not been consistent across studies.
This means that the absence of a patellar button does not automatically indicate that something was omitted. Likewise, having a resurfaced patella does not guarantee the absence of discomfort at the front of your knee.
If you are preparing for surgery and want a clearer understanding of the decisions ahead, visit The Knee Replacement Game Plan. You can also be a Total Knee Success Insider for new episodes and practical educational resources.
What Happens to the Ligaments?
The management of your ligaments depends partly on the implant design and your individual procedure. In a conventional total knee replacement, the anterior cruciate ligament, or ACL, is generally removed.
The posterior cruciate ligament, or PCL, may be retained or removed. A cruciate-retaining implant is designed to preserve the PCL. A posterior-stabilized implant uses components that provide stability without retaining the PCL. Other designs, including ultracongruent components, manage stability differently.
The medial and lateral collateral ligaments are usually preserved because they contribute to side-to-side stability. However, surgeons may perform controlled releases or use a more constrained implant when ligament integrity, deformity, or joint stability requires a different approach.
For that reason, broad statements about which ligaments are “always” preserved do not apply to every operation.
How to Find Out What Your Surgeon Did
Your operative report is the best place to find the details of your procedure. You can request a copy from your surgeon’s office, hospital