People with knee pain from arthritis or old injuries often wonder if they need knee replacement surgery. According to the Arthritis Foundation, individuals live with knee pain for an average of 13 years before opting for surgery.
Dr. David Silva Iacobelli, an orthopedic surgeon at the University of Miami Health System, emphasizes that knee surgery is an elective procedure. “I don’t like to say someone needs surgery,” says Dr. Iacobelli. He evaluates whether patients are good candidates, meaning they are likely to experience less pain, improved function, and a better quality of life after surgery.
Knee replacement may not be necessary for those whose arthritis is not advanced and whose symptoms are mild.
Doctors determine whether a patient needs a partial or total knee replacement based on which compartment of the knee is affected. The knee has three compartments: medial (inner side), lateral (outer side), and patellofemoral (front, under the kneecap). If pain and arthritis are limited to one compartment, partial replacement may be considered. More severe cases affecting all three compartments require total knee replacement.
Dr. Iacobelli explains that during either procedure, surgeons may resurface the patella by removing damaged cartilage and replacing it with plastic to help the kneecap move more smoothly.
Technological advances have improved surgical precision. “Traditional knee surgery insisted that everything be straight, so every patient got the same alignment, even though everyone’s anatomy differs,” says Dr. Iacobelli. Surgical robotics and navigation tools now allow for greater accuracy tailored to each patient’s anatomy. These tools assist surgeons but do not perform the operation independently. Some technologies generate 3D maps of the knee, guiding bone removal and implant placement.
“More precision gives you a better implant fit unique to your anatomy, as well as less damage to nearby soft tissues,” Dr. Iacobelli says.
Recovery protocols have also changed. In the past, patients often stayed in the hospital for up to a week after surgery. Now, many can walk on the same day as their operation due to advances in pain management and coordinated care involving physical therapists and nurses. “In the past, patients stayed in the hospital five to seven days, often in bed. Now, we aim to have most patients up and walking the same day,” says Dr. Iacobelli.
Most patients notice improvement within three months and reach full benefits after a year.
Knee replacement aims to reduce pain and restore function, but Dr. Iacobelli notes that a replaced joint will not feel exactly like a natural knee. Patients should expect a scar, possible numbness in a small area, and some stiffness that can improve with physical therapy. Activity levels after surgery vary depending on individual circumstances and rehabilitation efforts.
Some patients return to activities such as running or mountain climbing after surgery. However, Dr. Iacobelli warns against high-impact sports like marathon training because they can shorten implant lifespan: “Be active and enjoy the joint, but understand that more pounding usually means less longevity,” he says.
Improved surgical techniques have led younger patients—often in their mid-50s—to choose surgery earlier rather than waiting for more years of discomfort. Implants can last 20 to 30 years now, which influences this decision-making process. “In the past, we’d tell a 55-year-old with severe arthritis to wait until 65 to maximize implant longevity. Now, many don’t want to suffer for a decade. If they meet criteria, they opt in earlier,” says Dr. Iacobelli.
Looking ahead, biologic treatments such as stem cell therapy have potential but are not yet proven solutions for cartilage regeneration or reversing arthritis damage on X-rays. “Stem cells could one day regenerate cartilage, but much of what’s marketed as stem cells aren’t true stem cells and claims of arthritis disappearing on an X-ray after injections aren’t supported by evidence,” says Dr. Iacobelli.
For now, surgeons rely on better implants and techniques adapted to each patient’s anatomy: “Surgeons often develop expertise with a given system or switch when evidence and experience suggest an improvement,” says Dr. Iacobelli.
