The most common knee surgery is called arthroplasty, which is the medical term for knee replacement. Other major types include arthroscopy (a minimally invasive camera-guided procedure), osteotomy (bone realignment surgery), and ligament reconstruction. The specific name depends on what’s being fixed and how.
Arthroplasty: Knee Replacement Surgery
Arthroplasty is the term you’ll hear most often when people talk about knee surgery, especially for arthritis. It means replacing damaged joint surfaces with metal and plastic parts. There are two main versions.
A total knee replacement (total knee arthroplasty) replaces two or three surfaces of the knee joint. Your knee has three compartments: the inside, the outside, and the area behind the kneecap. Most people who need a replacement have damage in more than one of these areas, so total replacement is far more common.
A partial knee replacement (unicompartmental arthroplasty) replaces only the damaged section. This lets you keep more of your natural bone, tissue, and ligaments, but only a small percentage of patients qualify for it. The damage has to be limited to just one compartment of the knee.
To be considered a candidate for either type, you generally need two things: significant cartilage loss visible on a standing X-ray (seen as narrowing of the space between your knee bones) and enough pain or limited function that it’s affecting your quality of life. Surgeons don’t jump to replacement. It’s typically offered after physical therapy, medications, and other nonsurgical treatments have stopped working.
Arthroscopy: Minimally Invasive Knee Surgery
Arthroscopy is the umbrella term for surgeries performed through several small incisions using a tiny camera called an arthroscope. Rather than opening the knee up fully, the surgeon inserts the camera and small instruments through cuts roughly the size of a buttonhole. This approach is used for a wide range of problems that don’t require a full replacement.
The most common arthroscopic procedures include:
- Meniscus repair or removal: The meniscus is the rubbery cartilage that cushions the space between your thighbone and shinbone. A torn meniscus can be trimmed or stitched back together.
- Synovectomy: Removal of the synovium, the inflamed or damaged lining of the joint.
- Patellar debridement: Smoothing or cleaning up damaged cartilage around the kneecap.
- Lateral release: Loosening tight tissue on the outer side of the kneecap to improve its alignment.
Because the incisions are small, arthroscopic procedures generally involve less tissue disruption and a shorter recovery than open surgery.
Ligament Reconstruction
When you hear about athletes tearing their ACL, the surgery to fix it is called ACL reconstruction. The surgeon doesn’t simply stitch the torn ligament back together. Instead, the damaged ACL is replaced with a graft, a piece of tissue taken from another part of your body (usually part of your hamstring, quadriceps, or patellar tendon) or from a donor.
A newer, modernized version of ACL repair does involve sewing the torn tissue back together with sutures rather than replacing it entirely. Some surgeons believe this approach may lead to a quicker recovery, though reconstruction remains the standard treatment.
The same naming convention applies to other knee ligaments. PCL reconstruction, MCL repair, and similar terms describe the same concept applied to different ligaments in the knee. These surgeries are typically performed arthroscopically through small incisions.
Osteotomy: Bone Realignment Surgery
An osteotomy is a less well-known procedure where the surgeon cuts and reshapes bone to shift your body weight away from the damaged part of the knee. It’s designed for people who have arthritis concentrated on one side of the joint, and it works by redistributing the load onto healthier cartilage.
There are two techniques. In a closing wedge osteotomy, the surgeon removes a wedge of bone from the shinbone or thighbone on the healthy side of the knee. In an opening wedge osteotomy, a cut is made in the bone and a wedge is opened on the painful side. Both approaches change the angle of your leg to relieve pressure on the worn area.
Osteotomy is often chosen for younger, active patients who want to delay a full knee replacement. A successful osteotomy can postpone the need for replacement by up to 10 years while allowing you to stay active on your own natural joint.
Revision Arthroplasty
If a knee replacement eventually wears out or develops complications, the follow-up surgery is called revision total knee arthroplasty. It involves removing some or all of the original implant components and replacing them with new ones.
The most common reasons for revision include implant loosening over time, infection, instability from ligament damage, stiffness caused by scar tissue, and fractures around the implant from a fall. Modern knee replacements last a long time, though. About 93% of total knee replacements are still functioning at 15 years, 90% at 20 years, and roughly 82% at 25 years, based on data from large national registries tracking hundreds of thousands of patients.
What Recovery Looks Like
Recovery timelines vary significantly depending on the type of surgery. Arthroscopic procedures often have you back to normal activities within weeks. A total knee replacement follows a more structured path.
After a total replacement, a physical therapist typically helps you stand and walk with an assistive device on the first day. Most people move from a walker to a cane within two to three weeks, and many stop using any assistive device by weeks four to six. Physical therapy continues for about 12 weeks, sometimes longer. High-impact activities like running, skiing, and basketball are generally avoided long-term to protect the implant, though your surgeon may clear you for some higher-impact activities after the 12-week mark.
Robotic-assisted surgery has become increasingly common for knee replacements. Data from Cleveland Clinic found that patients who had robot-assisted procedures had shorter hospital stays (about half a day compared to just over one day for manual surgery) and were more likely to go home the same day. Surgeons report that robotic systems allow for more precise bone cuts and better ligament balancing, which may translate to less pain during recovery.