One of the most common causes of severe knee pain that may require replacement is osteoarthritis. Over time, the protective cartilage around the knee joint wears down due to regular use or injury. Without the cartilage cushion, the bones underneath can rub painfully against each other. For an estimated 10% of Americans aged 55 years and older, osteoarthritis leads to chronic knee pain and disability. Other conditions less frequently requiring knee replacement include rheumatoid arthritis, severe injuries such as fractures, and rare bone or joint disorders.

The Surgical Procedure for Knee Replacement
During knee replacement surgery, the surgeon removes damaged bone and cartilage and replaces them with prosthetic components. The three main parts implanted are the femoral component (attached to the end of the thighbone), the tibial component (attached to the top of the shinbone), and a plastic spacer called an insert that acts as a meniscal cushion between the metal parts. The goal is to relieve pain and restore smooth movement of the knee joint. Surgery is performed under general or spinal anesthesia and usually takes 1 to 2 hours. Patients typically stay in the hospital for only a few days and begin physical therapy soon after to aid the recovery process.

Types of Knee Replacements Available
There are a few different types available depending on a patient's needs and circumstances. Total knee replacement involves replacing all three parts of the knee joint with prosthetics. Partial knee replacement only replaces damaged areas, preserving as much natural bone and ligament as possible. Revision surgery may be needed if a previous replacement wears out or fails to provide relief. Unicompartmental or minimally invasive techniques focus on either the inner or outer half of the knee rather than operating on the entire joint.

Rehabilitation After Knee Replacement Surgery
Physical therapy and lifestyle changes play a key role in achieving the best possible outcome following knee replacement. Regular sessions with a physical therapist aim to strengthen the muscles around the new joint, improve mobility and flexibility, and reestablish a full range of comfortable motion. Immediate exercises focus on simple motions of the knee and ankle while avoiding placing excessive weight on the new prosthesis. Milestones include being able to fully straighten and bend the knee, walk without assistance, and eventually resume regular daily activities. Most patients are able to drive again within 6 weeks but may need 4-6 months to return to more vigorous sports or jobs requiring kneeling or heavy lifting. Ongoing exercises help ensure the knee replacement prosthesis lasts as long as possible.

Success Rates of Knee Replacements
Overall, knee replacement surgery achieves excellent success for relieving arthritis pain and regaining mobility. Around 90% of primary knee replacements last 15 years or more before needing potential revision. Patient satisfaction with the results is typically high. However, active individuals or those with more physically demanding lifestyles may experience slightly sooner wearing of the prosthetic components. Following rehabilitation guidelines and limiting high-impact activities can help maximize the lifespan of a knee replacement. Age, medical history, obesity, smoking status, and postoperative complications can also affect long-term outcomes. With the knowledge gained from millions of procedures performed, surgeons continuously work to extend success rates even further.

Alternative and Advancements in Knee Replacement Care
For those not ready for surgery or whose arthritis is still in earlier stages, nonsurgical options may help control symptoms. Weight loss if overweight, bracing, medications, injections, or arthroscopic treatments seek to delay or avoid the need for replacement. For active patients concerned about lasting decades, newer advancements attempt to extend prosthesis endurance. These include highly crosslinked polyethylene plastic inserts more resistant to wear, resurfacing techniques preserving more natural bone, and improved prosthetic alignment and fixation methods. Ongoing research also evaluates biologic solutions such as repairing cartilage naturally or regenerating entirely new joint surfaces. While knee replacement remains very effective for most, continual innovation works to address all patient situations.

In summary, knee replacement surgery has provided relief for millions of arthritis sufferers and successfully restored mobility. Despite a major operation and rehabilitation period, implanted prosthetics typically last 15 years or more before potential replacement. By carefully selecting patients and employing the latest techniques, orthopedic surgeons achieve highly favorable outcomes. Ongoing research further enhances options and lengthens the lifespan of new knee joints. As life expectancies rise, knee replacement will likely remain an important solution to allow active aging and economic participation whenever nonoperative care no longer sufficiently controls symptoms.