There are several conditions that can cause severe knee pain and reduce mobility to the point where this surgery becomes necessary. Osteoarthritis is the most common cause, where the protective cartilage on the knee bones gradually wears away over many years. This causes the bones to rub together painfully. Other causes include rheumatoid arthritis, injury-related arthritis from past ligament or meniscal tears, and rarely, worn metal or plastic implants from a prior knee replacement.

Types

There are two main types of surgery:

Partial Knee Replacement
This involves resurfacing just one part of the knee, either the tibia (shinbone) or the femur (thighbone) while leaving other parts intact. It is suitable for isolated arthritis in only one area of the knee.

Total Knee Replacement
The surgeon removes damaged bone and cartilage and replaces them with prosthetic components. These include plastic spacers to mimic cartilage and metal components to replace the ends of the femur and tibia. Some designs also include a plastic patella (kneecap) component. This is the most common type for advanced arthritis affecting multiple surfaces of the knee joint.

Surgical Procedure for Total Knee Replacement

During surgery, the patient will be given general or spinal anesthesia. An incision is made on the front of the knee, usually 8-12 inches long. The surgeon carefully cuts away the damaged cartilage and bone. Trial prosthetic components are fitted to determine the appropriate size. The metal femoral and tibial components are firmly fixed with bone cement. A plastic spacer is positioned between them. Patellar resurfacing may also be performed if needed. The incision is stitched closed. Surgery usually takes 1-2 hours.

Rehabilitation and Recovery Process

For the first few days after surgery, patients will have some pain, swelling, and bruising around the new knee. Physical therapists will help the patient begin simple leg exercises and walk with assistance as able. As the pain and swelling subside, the exercises become more advanced to restore full movement and strengthen the muscles. Most people can walk unassisted within a few weeks.

Recovery Timeline After Surgery

- Weeks 1-2: Focus is on regaining movement and independence with daily activities. Use crutches, walker or cane as needed.

- Weeks 3-6: Graduated strengthening exercises. Swelling continues decreasing. Stair climbing is introduced.

- Months 3-6: Work to restore full range of motion and muscle strength. Low impact activities like biking or swimming may begin.

- Month 6 Onwards: Most people report significant pain relief by 6 months. Impact activities may slowly resume like golf or doubles tennis. Recovery generally plateaus by 1 year.

Outcomes and Longevity of Knee Replacements

With rehabilitation, more than 90% of patients report dramatic pain relief and improved function within 6-12 months. Modern implants are designed to last 15-30 years on average before possibly requiring revision surgery to replace worn components. Proper aftercare maximizes the lifespan of the implants. While it is a major surgery, it can allow individuals to return to everyday activities and sports that were previously not possible due to severe arthritis pain. With an appropriate candidate and good outcomes, it can be an excellent treatment option to improve quality of life.

Outpatient Versus Inpatient

Historically, knee replacements required a 5-7 day hospital stay for recovery. Now many centers offer outpatient or short-stay options for select patients who meet criteria like having home care support. Research shows properly selected outpatients have similar outcomes to inpatients with less risk of hospital-acquired infections. This option has become more popular due to increased comfort of patients in their own home environments during initial recovery. Close follow up visits with the surgeon still occur as normal.

Potential Complications of Surgery

As with any surgical procedure, there are risks such as infection, blood clots, instability, stiffness and limitation of movement. However, advancements in implants, pharmaceuticals, and surgical technique have reduced these risks tremendously in developed countries. With appropriate pre-op planning and rehabilitation, the majority of knee replacement patients experience excellent relief of arthritis pain and improved lifestyle function for many years. While there may be touch ups, adjustments or even future revision surgeries in rare cases, it remains one of the most successful and life-changing orthopedic procedures today